Antennas for 100 Pound DXpeditions - | NE1RD ~ Home · ANTENNAS FOR 100 POUND DXPEDITIONS 8.2.4 Buddipole Vertical with L-arm radial for 17m at 8 feet.....108

Antennas for 100 Pound DXpeditions

Computer-based antenna modeling and direct experience with lightweight portable antenna systems

Volume 1: Selected high band antennas [20-6m]

B. Scott Andersen

NE1RD

ANTENNAS FOR 100 POUND DXPEDITIONS

White Paper – Version 1.01 Copyright 2007-2008 B. Scott Andersen

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TABLE OF CONTENTS

1 THE 100 POUND DXPEDITION................................................................................ 1

2 ANTENNA ASPECTS OF DXPEDITIONING ............................................................ 2

3 SOME NOTES ON MODELING ................................................................................ 5

4 PHYSICAL MEASUREMENT.................................................................................... 6

5 REFERENCE ANTENNAS........................................................................................ 7

5.1 Quarter-wave verticals ..........................................................................................................................7 5.1.1 10 meter Quarter-wave Vertical with Radials ..............................................................................7 5.1.2 12 meter Quarter-wave Vertical with Radials ............................................................................12 5.1.3 15 meter Quarter-wave Vertical with Radials ............................................................................15 5.1.4 17 meter Quarter-wave Vertical with Radials ............................................................................18 5.1.5 20 meter Quarter-wave Vertical with Radials ............................................................................21

5.2 Half-wave vertical dipoles ...................................................................................................................24 5.2.1 Full-sized 10 Meter Vertical Dipole.............................................................................................24 5.2.2 Full-sized 12 Meter Vertical Dipole.............................................................................................27 5.2.3 Full-sized 15 Meter Vertical Dipole.............................................................................................30 5.2.4 Full-sized 17 Meter Vertical Dipole.............................................................................................33 5.2.5 Full-sized 20 Meter Vertical Dipole.............................................................................................36

6 FORCE-12 SIGMA-5 ANTENNA............................................................................. 39

6.1 Force-12 Sigma-5 on 10 meters ........................................................................................................39 6.1.1 Model description ........................................................................................................................42 6.1.2 Analysis ........................................................................................................................................45

6.2 Force-12 Sigma-5 matching coil calculations....................................................................................47 6.3 Force-12 Sigma-5 on 12 meters ........................................................................................................48 6.4 Force-12 Sigma-5 on 15 meters ........................................................................................................51 6.5 Force-12 Sigma-5 on 17 meters ........................................................................................................53 6.6 Force-12 Sigma-5 on 20 meters ........................................................................................................54

7 TW ANTENNAS TW2010 TRAVELER ................................................................... 57

7.1 TW Antennas TW2010 Traveler on 10 meters .................................................................................57 7.2 TW Antennas TW2010 Traveler matching coil calculations.............................................................62 7.3 TW Antennas Traveler on 12 meters.................................................................................................64 7.4 TW Antennas Traveler on 15 meters.................................................................................................68 7.5 TW Antennas Traveler on 17 meters.................................................................................................71 7.6 TW Antennas Traveler on 20 meters.................................................................................................75

8 STANDARD BUDDIPOLE ...................................................................................... 80

8.1 Buddipole Horizontal Dipole ...............................................................................................................83 8.1.1 Buddipole Horizontal Dipole for 10-meters at 8 feet .................................................................83 8.1.2 Buddipole Horizontal Dipole for 10-meters at 16 feet ...............................................................86 8.1.3 Buddipole Horizontal Dipole for 12-meters at 16 feet ...............................................................89 8.1.4 Buddipole Horizontal Dipole for 15-meters at 16 feet ...............................................................92 8.1.5 Buddipole Horizontal Dipole for 17-meters at 16 feet ...............................................................95

8.2 Buddipole Vertical with L-arm radial at 8 feet....................................................................................98 8.2.1 Buddipole Vertical with L-arm radial for 10m at 8 feet ..............................................................98 8.2.2 Buddipole Vertical with L-arm radial for 12m at 8 feet ............................................................101 8.2.3 Buddipole Vertical with L-arm radial for 15m at 8 feet ............................................................104


8.2.4 Buddipole Vertical with L-arm radial for 17m at 8 feet ............................................................108 8.2.5 Buddipole Vertical with L-arm radial for 20m at 8 feet ............................................................111

8.3 Buddipole Vertical with L-arm radial at 16 feet ...............................................................................114 8.3.1 Buddipole Vertical with L-arm radial for 10m at 16 feet ..........................................................114 8.3.2 Buddipole Vertical with L-arm radial for 12m at 16 feet ..........................................................117 8.3.3 Buddipole Vertical with L-arm radial for 15m at 16 feet ..........................................................120 8.3.4 Buddipole Vertical with L-arm radial for 17m at 16 feet ..........................................................123 8.3.5 Buddipole Vertical with L-arm radial for 20m at 16 feet ..........................................................126

8.4 Buddipole vertical with single sloping radial at 16 feet ...................................................................129 8.4.1 Buddipole vertical with 1 radial for 10m at 16 feet ..................................................................129 8.4.2 Buddipole vertical with 1 radial for 12m at 8 feet ....................................................................132 8.4.3 Buddipole vertical with 1 radial for 15m at 8 feet ....................................................................135 8.4.4 Buddipole vertical with 1 radial for 17m at 16 feet ..................................................................138 8.4.5 Buddipole vertical with 1 radial for 20m at 16 feet ..................................................................141

9 LONG BUDDIPOLE .............................................................................................. 144

9.1 Differences between the Standard Buddipole and Long Buddipole ..............................................144 9.2 Buddipole full-sized vertical with 1 radial 8 feet ..............................................................................144

9.2.1 Buddipole full-sized vertical with 1 radial for 10m at 8 feet ....................................................144 9.2.2 Buddipole full-sized vertical with 1 radial for 12m at 8 feet ....................................................148 9.2.3 Buddipole full-sized vertical with 1 radial for 15m at 8 feet ....................................................151 9.2.4 Buddipole full-sized vertical with 1 radial for 17m at 8 feet ....................................................154 9.2.5 Buddipole full-sized vertical with 1 radial for 20m at 8 feet ....................................................157

9.3 Buddipole full-sized vertical with 4 radials at 8 feet ........................................................................160 9.3.1 Buddipole full-sized vertical with 4 radials for 10m at 8 feet ..................................................160 9.3.2 Buddipole full-sized vertical with 4 radials for 12m at 8 feet ..................................................163 9.3.3 Buddipole full-sized vertical with 4 radial for 15m at 8 feet ....................................................166 9.3.4 Buddipole full-sized vertical with 4 radials for 17m at 8 feet ..................................................169 9.3.5 Buddipole full-sized vertical with 4 radials for 20m at 8 feet ..................................................172

9.4 Buddipole full-sized vertical with 1 radial at 16 feet ........................................................................175 9.4.1 Buddipole full-sized vertical with 1 radial for 10m at 16 feet ..................................................175 9.4.2 Buddipole full-sized vertical with 1 radial for 12m at 16 feet ..................................................178 9.4.3 Buddipole full-sized vertical with 1 radial for 15m at 16 feet ..................................................181 9.4.4 Buddipole full-sized vertical with 1 radial for 17m at 16 feet ..................................................184 9.4.5 Buddipole full-sized vertical with 1 radial for 20m at 16 feet ..................................................187

9.5 Buddipole comparisons and conclusions ........................................................................................190 9.5.1 Gain and take-off angles of configurations ..............................................................................190 9.5.2 Comparing Buddipole to Force-12 Sigma-5 ............................................................................191

10 SMALL ANTENNAS 10-20M CONCLUSIONS................................................... 197

11 THE EFFECTS OF GROUND ............................................................................. 199

11.1 Long ground radials for the Force-12 Sigma-5 .............................................................................199 11.2 The effects of radial length on a vertical dipole.............................................................................204 11.3 Dual-length radials ..........................................................................................................................208

12 BALCONY ANTENNAS ...................................................................................... 212

12.1 Problem description ........................................................................................................................212 12.2 20 meters .........................................................................................................................................212

12.2.1 Fishing pole horizontal antenna .............................................................................................212

13 ANTENNAS FOR 6M .......................................................................................... 217

13.1 Hentenna from the Buddipole Users Group ..................................................................................217

14 FINAL COMMENTS TO VOLUME 1................................................................... 221


APPENDIX A BUDDIPOLE COIL INDUCTANCES.................................................... 223

BUDDIPOLE LOW BAND COILS............................................................................... 224

REFERENCES............................................................................................................ 225


LIST OF FIGURES

Figure 1 AntennaSmith by Time Wave ..............................................................................................................6 Figure 2 On-screen plots viewed on the AntennaSmith ...................................................................................6 Figure 3 Full-sized 10m quarter-wave vertical ..................................................................................................8 Figure 4 SWR for quarter wave vertical on 12m ...............................................................................................9 Figure 5 Quarter wave vertical on 10m over good ground .............................................................................10 Figure 6 Quarter wave vertical on 10m over poor ground..............................................................................10 Figure 7 Full-sized 12m quarter-wave vertical ................................................................................................12 Figure 8 SWR for quarter wave vertical on 12m .............................................................................................13 Figure 9 Quarter wave vertical on 12m over good ground .............................................................................14 Figure 10 Quarter wave vertical on 12m over poor ground............................................................................14 Figure 11 Full-sized 15m quarter-wave vertical ..............................................................................................15 Figure 12 SWR for quarter wave vertical on 15m ...........................................................................................16 Figure 13 Quarter wave vertical on 15m over good ground ...........................................................................17 Figure 14 Quarter wave vertical on 15m over poor ground............................................................................17 Figure 15 Full-sized 17m quarter-wave vertical ..............................................................................................18 Figure 16 SWR for quarter wave vertical on 17m ...........................................................................................19 Figure 17 Quarter wave vertical on 17m over good ground ...........................................................................20 Figure 18 Quarter wave vertical on 17m over poor ground............................................................................20 Figure 19 Full-sized 20m quarter-wave vertical ..............................................................................................21 Figure 20 SWR for quarter wave vertical on 20m ...........................................................................................22 Figure 21 Quarter wave vertical on 20m over good ground ...........................................................................23 Figure 22 Quarter wave vertical on 20m over poor ground............................................................................23 Figure 23 View of the full-sized 10 meter vertical dipole ................................................................................24 Figure 24 SWR for half wave vertical dipole on 10m......................................................................................25 Figure 25 Half-wave vertical dipole on 10m over good ground......................................................................26 Figure 26 Half-wave vertical dipole on 10m over poor ground.......................................................................27 Figure 27 View of the full-sized 12 meter vertical dipole ................................................................................27 Figure 28 SWR for half wave vertical dipole on 12m......................................................................................28 Figure 29 Half-wave vertical dipole on 12m over good ground......................................................................29 Figure 30 Half-wave vertical dipole on 12m over poor ground.......................................................................29 Figure 31 View of the full-sized 15 meter vertical dipole ................................................................................30 Figure 32 SWR for half wave vertical dipole on 15m......................................................................................31 Figure 33 Half-wave vertical dipole on 15m over good ground......................................................................32 Figure 34 Half-wave vertical dipole on 15m over poor ground.......................................................................32 Figure 35 View of the full-sized 17 meter vertical dipole ................................................................................33 Figure 36 SWR for half wave vertical dipole on 17m......................................................................................34 Figure 37 Half-wave vertical dipole on 17m over good ground......................................................................35 Figure 38 Half-wave vertical dipole on 17m over poor ground.......................................................................35 Figure 39 View of the full-sized 20 meter vertical dipole ................................................................................36 Figure 40 SWR for half wave vertical dipole on 20m......................................................................................37 Figure 41 Half-wave vertical dipole on 20m over good ground......................................................................38 Figure 42 Half-wave vertical dipole on 20m over poor ground.......................................................................38 Figure 43 The assembled Force-12 Sigma-5 ..................................................................................................40 Figure 44 Force-12 Sigma-5 matching circuit..................................................................................................41 Figure 45 Force-12 Sigma-5 element diameters.............................................................................................42 Figure 46 EZNEC antenna view of Sigma-5....................................................................................................45 Figure 47 SWR for Force-12 Sigma-5 on 10 meters ......................................................................................45 Figure 48 Force-12 Sigma-5 on 10m over good ground ................................................................................46 Figure 49 Force-12 Sigma-5 on 10m over poor ground .................................................................................46 Figure 50 EL 10m quarter wave and vertical dipole over poor ground..........................................................47 Figure 51 SWR for Force-12 Sigma-5 on 12 meters ......................................................................................49 Figure 52 Force-12 Sigma-5 on 12m over good ground ................................................................................50


Figure 53 Force-12 Sigma-5 on 12m over poor ground .................................................................................50 Figure 54 SWR for Force-12 Sigma-5 on 15 meters ......................................................................................51 Figure 55 Force-12 Sigma-5 on 15m over good ground ................................................................................52 Figure 56 Force-12 Sigma-5 on 15m over poor ground .................................................................................52 Figure 57 SWR for Force-12 Sigma-5 on 17 meters ......................................................................................53 Figure 58 Force-12 Sigma-5 on 17m over good ground ................................................................................54 Figure 59 Force-12 Sigma-5 on 17m over poor ground .................................................................................54 Figure 60 SWR for Force-12 Sigma-5 on 20 meters ......................................................................................55 Figure 61 Force-12 Sigma-5 on 20m over good ground ................................................................................56 Figure 62 Force-12 Sigma-5 on 20m over poor ground .................................................................................56 Figure 63 TW Antennas Traveler model view .................................................................................................58 Figure 64 SWR for TW Antennas Traveler on 10m ........................................................................................59 Figure 65 TW Antennas Traveler on 10m over good ground .........................................................................59 Figure 66 TW Antennas Traveler on 10m over poor ground..........................................................................60 Figure 67 AZ Sigma-5 and Traveler on 10m over good ground ....................................................................60 Figure 68 EL Sigma-5 and Traveler on 10m over good ground.....................................................................61 Figure 69 AZ Sigma-5 and Traveler on 10m over poor ground .....................................................................61 Figure 70 EL Sigma-5 and Traveler on 10m over poor ground......................................................................62 Figure 71 Measuring Traveler coils with Photoshop .......................................................................................63 Figure 72 SWR for TW Antennas Traveler on 12m ........................................................................................64 Figure 73 TW Antennas Traveler on 12m over good ground.........................................................................65 Figure 74 TW Antennas Traveler on 12m over poor ground..........................................................................65 Figure 75 AZ Sigma-5 and Traveler on 12m over good ground ....................................................................66 Figure 76 EL Sigma-5 and Traveler on 12m over good ground.....................................................................66 Figure 77 AZ Sigma-5 and Traveler on 12m over poor ground .....................................................................67 Figure 78 EL Sigma-5 and Traveler on 12m over poor ground......................................................................67 Figure 79 SWR for TW Antennas Traveler on 15m ........................................................................................68 Figure 80 TW Antennas Traveler over good ground.......................................................................................69 Figure 81 TW Antennas Traveler on 15m over poor ground..........................................................................69 Figure 82 AZ Sigma-5 and Traveler on 15m over good ground ....................................................................70 Figure 83 EL Sigma-5 and Traveler on 15m over good ground.....................................................................70 Figure 84 AZ Sigma-5 and Traveler on 15m over poor ground .....................................................................71 Figure 85 AZ Sigma-5 and Traveler on 15m over poor ground .....................................................................71 Figure 86 SWR for TW Antennas Traveler on 17m ........................................................................................72 Figure 87 TW Antennas Traveler on 17m over good ground.........................................................................73 Figure 88 TW Antennas Traveler on 17m over poor ground..........................................................................73 Figure 89 AZ Sigma-5 and Traveler on 17m over good ground ....................................................................74 Figure 90 EL Sigma-5 and Traveler on 17m over good ground.....................................................................74 Figure 91 AZ Sigma-5 and Traveler on 17m over poor ground .....................................................................75 Figure 92 EL Sigma-5 and Traveler on 17m over poor ground......................................................................75 Figure 93 SWR for TW Antennas Traveler on 20m ........................................................................................76 Figure 94 TW Antennas Traveler on 20m over good ground .........................................................................77 Figure 95 TW Antennas Traveler on 20m over poor ground..........................................................................77 Figure 96 AZ Sigma-5 and Traveler on 20m over good ground ....................................................................78 Figure 97 EL Sigma-5 and Traveler on 20m over good ground.....................................................................78 Figure 98 AZ Sigma-5 and Traveler on 20m over poor ground .....................................................................79 Figure 99 EL Sigma-5 and Traveler on 20m over poor ground......................................................................79 Figure 100Buddipole in the bag........................................................................................................................81 Figure 101 Buddipole on 10m at 8 feet............................................................................................................84 Figure 102 Buddipole horizontal dipole for 10m at 8 feet over good ground ................................................85 Figure 103 Buddipole horizontal dipole for 10m at 8 feet over poor ground .................................................85 Figure 104 SWR for Buddipole horizontal dipole for 10m at 16 feet..............................................................87 Figure 105 Buddipole horizontal dipole for 10m at 16 feet over good ground ..............................................88 Figure 106 Buddipole horizontal dipole for 10m at 16 feet over poor ground ...............................................88 Figure 107 Half-wave vertical dipole vs. Buddipole horizontal dipole for 10 meters ....................................89


Figure 108 SWR for Buddipole horizontal dipole for 12m at 16 feet..............................................................90 Figure 109 Buddipole horizontal dipole for 12m at 16 feet over good ground ..............................................91 Figure 110 Buddipole horizontal dipole for 12m at 16 feet over poor ground ...............................................91 Figure 111 SWR for Buddipole horizontal dipole for 15m at 16 feet..............................................................93 Figure 112 Buddipole horizontal dipole for 15m at 16 feet over good ground ..............................................94 Figure 113 Buddipole horizontal dipole for 15m at 16 feet over poor ground ...............................................94 Figure 114 SWR for Buddipole horizontal dipole for 17m at 16 feet..............................................................96 Figure 115 Buddipole horizontal dipole for 17m at 16 feet over good ground ..............................................97 Figure 116 Buddipole horizontal dipole for 17m at 16 feet over poor ground ...............................................97 Figure 117 SWR for Buddipole vertical with L-radial on 10m at 8 feet ..........................................................99 Figure 118 Buddipole vertical with L-radial on 10m at 8 feet .......................................................................100 Figure 119 Buddipole vertical with L-radial on 10m at 8 feet over good ground.........................................100 Figure 120 Buddipole vertical with L-radial on 10m at 8 feet over poor ground .........................................101 Figure 121 Buddipole vertical with L-radial on 12m at 8 feet .......................................................................101 Figure 122 SWR for Buddipole vertical with L-radial on 12m at 8 feet ........................................................103 Figure 123 Buddipole vertical with L-radial on 12m at 8 feet over good ground.........................................103 Figure 124 Buddipole vertical with L-radial on 12m at 8 feet over poor ground .........................................104 Figure 125 Buddipole vertical with L-radial on 15m at 8 feet .......................................................................104 Figure 126 SWR for Buddipole vertical with L-radial on 15m at 8 feet ........................................................106 Figure 127 Buddipole vertical with L-radial on 15m at 8 feet over good ground.........................................107 Figure 128 Buddipole vertical with L-radial on 15m at 8 feet over poor ground .........................................107 Figure 129 Buddipole vertical with L-radial on 17m at 8 feet .......................................................................108 Figure 130 SWR for Buddipole vertical with L-radial on 17m at 8 feet ........................................................109 Figure 131 Buddipole vertical with L-radial on 17m at 8 feet over good ground.........................................110 Figure 132 Buddipole vertical with L-radial on 17m at 8 feet over poor ground .........................................110 Figure 133 Buddipole vertical with L-radial on 20m at 8 feet .......................................................................111 Figure 134 SWR for Buddipole vertical with L-radial on 20m at 8 feet ........................................................112 Figure 135 Buddipole vertical with L-radial on 20m at 8 feet over good ground.........................................113 Figure 136 Buddipole vertical with L-radial on 20m at 8 feet over poor ground .........................................113 Figure 137 Buddipole vertical with L-radial on 10m at 16 feet .....................................................................114 Figure 138 SWR for Buddipole vertical with L-radial on 10m at 16 feet ......................................................115 Figure 139 Buddipole vertical with L-radial on 10m at 16 feet over good ground.......................................116 Figure 140 Buddipole vertical with L-radial on 10m at 16 feet over poor ground .......................................116 Figure 141 Buddipole vertical with L-radial on 12m at 16 feet .....................................................................117 Figure 142 SWR for Buddipole vertical with L-radial on 12m at 16 feet ......................................................118 Figure 143 Buddipole vertical with L-radial on 12m at 16 feet over good ground.......................................119 Figure 144 Buddipole vertical with L-radial on 12m at 16 feet over poor ground .......................................119 Figure 145 Buddipole vertical with L-radial on 15m at 16 feet .....................................................................120 Figure 146 SWR for Buddipole vertical with L-radial on 15m at 16 feet ......................................................121 Figure 147 Buddipole vertical with L-radial on 15m at 16 feet over good ground.......................................122 Figure 148 Buddipole vertical with L-radial on 15m at 16 feet over poor ground .......................................122 Figure 149 Buddipole vertical with L-radial on 17m at 16 feet .....................................................................123 Figure 150 SWR for Buddipole vertical with L-radial on 17m at 16 feet ......................................................124 Figure 151 Buddipole vertical with L-radial on 17m at 16 feet over good ground.......................................125 Figure 152 Buddipole vertical with L-radial on 17m at 16 feet over poor ground .......................................125 Figure 153 Buddipole vertical with L-radial on 20m at 16 feet .....................................................................126 Figure 154 SWR for Buddipole vertical with L-radial on 20m at 16 feet ......................................................127 Figure 155 Buddipole vertical with L-radial on 20m at 16 feet over good ground.......................................128 Figure 156 Buddipole vertical with L-radial on 20m at 16 feet over poor ground .......................................128 Figure 157 Buddipole vertical for 10m with 1 radial ......................................................................................129 Figure 158 SWR for Buddipole vertical with 1 radial on 10m at 16 feet ......................................................130 Figure 159 Buddipole vertical with 1 radial on 10m at 16 feet over good ground.......................................131 Figure 160 Buddipole vertical with 1 radial on 10m at 16 feet over poor ground........................................131 Figure 161 Buddipole vertical for 12m with 1 radial ......................................................................................132 Figure 162 SWR for Buddipole vertical with 1 radial on 12m at 16 feet ......................................................133 Figure 163 Buddipole vertical with 1 radial on 12m at 16 feet over good ground.......................................134


Figure 164 Buddipole vertical with 1 radial on 12m at 16 feet over poor ground........................................134 Figure 165 Buddipole vertical for 15m with 1 radial ......................................................................................135 Figure 166 SWR for Buddipole vertical with 1 radial on 15m at 16 feet ......................................................136 Figure 167 Buddipole vertical with 1 radial on 15m at 16 feet over good ground.......................................137 Figure 168 Buddipole vertical with 1 radial on 15m at 16 feet over poor ground........................................137 Figure 169 Buddipole vertical for 17m with 1 radial ......................................................................................138 Figure 170 SWR for Buddipole vertical with 1 radial on 17m at 16 feet ......................................................139 Figure 171 Buddipole vertical with 1 radial on 17m at 16 feet over good ground.......................................140 Figure 172 Buddipole vertical with 1 radial on 17m at 16 feet over poor ground........................................140 Figure 173 Buddipole vertical for 20m with 1 radial ......................................................................................141 Figure 174 SWR for Buddipole vertical with 1 radial on 20m at 16 feet ......................................................142 Figure 175 Buddipole vertical with 1 radial on 20m at 16 feet over good ground.......................................143 Figure 176 Buddipole vertical with 1 radial on 20m at 16 feet over poor ground........................................143 Figure 177 Buddipole full-sized vertical for 10m with 1 radial ......................................................................145 Figure 178 SWR for BP full-sized vertical with 1 radial on 10m at 8 feet ....................................................146 Figure 179 BP full-sized vertical with 1 radial on 10m at 8 feet over good ground.....................................147 Figure 180 Buddipole full-sized vertical, 1 radial on 10m at 8 feet over poor ground ................................147 Figure 181 Buddipole full-sized vertical for 12m with 1 radial ......................................................................148 Figure 182 SWR for BP full-sized vertical with 1 radial on 12m at 8 feet ....................................................149 Figure 183 BP full-sized vertical with 1 radial on 12m at 8 feet over good ground.....................................150 Figure 184 Buddipole full-sized vertical, 1 radial on 12m at 8 feet over poor ground ................................150 Figure 185 Buddipole full-sized vertical for 15m with 1 radial ......................................................................151 Figure 186 SWR for BP full-sized vertical with 1 radial on 10m at 8 feet ....................................................152 Figure 187 BP full-sized vertical with 1 radial on 15m at 8 feet over good ground.....................................153 Figure 188 Buddipole full-sized vertical, 1 radial on 15m at 8 feet over poor ground ................................153 Figure 189 Buddipole full-sized vertical for 17m with 1 radial ......................................................................154 Figure 190 SWR for BP full-sized vertical with 1 radial on 17m at 8 feet ....................................................155 Figure 191 BP full-sized vertical with 1 radial on 10m at 8 feet over good ground.....................................156 Figure 192 Buddipole full-sized vertical, 1 radial on 17m at 8 feet over poor ground ................................156 Figure 193 Buddipole full-sized vertical for 20m with 1 radial ......................................................................157 Figure 194 SWR for BP full-sized vertical with 1 radial on 20m at 8 feet ....................................................158 Figure 195 BP full-sized vertical with 1 radial on 20m at 8 feet over good ground.....................................159 Figure 196 Buddipole full-sized vertical, 1 radial on 20m at 8 feet over poor ground ................................159 Figure 197 Buddipole full-sized vertical for 10m with 4 radials ....................................................................160 Figure 198 SWR for BP full-sized vertical with 4 radials on 10m at 8 feet ..................................................161 Figure 199 BP full-sized vertical with 4 radials on 10m at 8 feet over good ground...................................162 Figure 200 Buddipole full-sized vertical, 4 radials on 10m at 8 feet over poor ground ..............................162 Figure 201 Buddipole full-sized vertical for 12m with 4 radials ....................................................................163 Figure 202 SWR for BP full-sized vertical with 4 radial on 12m at 8 feet ....................................................164 Figure 203 BP full-sized vertical with 4 radial on 12m at 8 feet over good ground.....................................165 Figure 204 Buddipole full-sized vertical, 4 radials on 12m at 8 feet over poor ground ..............................165 Figure 205 Buddipole full-sized vertical for 15m with 4 radials ....................................................................166 Figure 206 SWR for BP full-sized vertical with 4 radials on 10m at 8 feet ..................................................167 Figure 207 BP full-sized vertical with 4 radials on 15m at 8 feet over good ground...................................168 Figure 208 Buddipole full-sized vertical, 4 radials on 15m at 8 feet over poor ground ..............................168 Figure 209 Buddipole full-sized vertical for 17m with 4 radials ....................................................................169 Figure 210 SWR for BP full-sized vertical with 4 radials on 17m at 8 feet ..................................................170 Figure 211 BP full-sized vertical with 4 radials on 10m at 8 feet over good ground...................................171 Figure 212 Buddipole full-sized vertical, 4 radials on 17m at 8 feet over poor ground ..............................171 Figure 213 Buddipole full-sized vertical for 20m with 4 radials ....................................................................172 Figure 214 SWR for BP full-sized vertical with 4 radials on 20m at 8 feet ..................................................173 Figure 215 BP full-sized vertical with 4 radials on 20m at 8 feet over good ground...................................174 Figure 216 Buddipole full-sized vertical, 4 radials on 20m at 8 feet over poor ground ..............................174 Figure 217 Buddipole full-sized vertical for 10m with 1 radial ......................................................................175 Figure 218 SWR for BP full-sized vertical with 1 radial on 10m at 16 feet..................................................176


Figure 219 BP full-sized vertical with 1 radial on 10m at 16 feet over good ground ..................................177 Figure 220 Buddipole full-sized vertical, 1 radial on 10m at 16 feet over poor ground ..............................177 Figure 221 Buddipole full-sized vertical for 12m with 1 radial ......................................................................178 Figure 222 SWR for BP full-sized vertical with 1 radial on 12m at 16 feet..................................................179 Figure 223 BP full-sized vertical with 1 radial on 12m at 16 feet over good ground ..................................180 Figure 224 Buddipole full-sized vertical, 1 radial on 12m at 16 feet over poor ground ..............................180 Figure 225 Buddipole full-sized vertical for 15m with 1 radial ......................................................................181 Figure 226 SWR for BP full-sized vertical with 1 radial on 10m at 16 feet ..................................................182 Figure 227 BP full-sized vertical with 1 radial on 15m at 16 feet over good ground ..................................183 Figure 228 Buddipole full-sized vertical, 1 radial on 15m at 16 feet over poor ground ..............................183 Figure 229 Buddipole full-sized vertical for 17m with 1 radial ......................................................................184 Figure 230 SWR for BP full-sized vertical with 1 radial on 17m at 16 feet..................................................185 Figure 231 BP full-sized vertical with 1 radial on 10m at 16 feet over good ground ..................................186 Figure 232 Buddipole full-sized vertical, 1 radial on 17m at 16 feet over poor ground ..............................186 Figure 233 Buddipole full-sized vertical for 20m with 1 radial ......................................................................187 Figure 234 SWR for BP full-sized vertical with 1 radial on 20m at 16 feet..................................................188 Figure 235 BP full-sized vertical with 1 radial on 20m at 16 feet over good ground ..................................189 Figure 236 Buddipole full-sized vertical, 1 radial on 20m at 16 feet over poor ground ..............................189 Figure 237 Force-12 Sigma-5 vs. BP full-sized vertical on 10m azimuth....................................................192 Figure 238 Force-12 Sigma-5 vs. BP full-sized vertical on 10m elevation ..................................................192 Figure 239 Force-12 Sigma-5 vs. BP full-sized vertical on 12m azimuth....................................................193 Figure 240 Force-12 Sigma-5 vs. BP full-sized vertical on 12m elevation ..................................................193 Figure 241 Force-12 Sigma-5 vs. BP full-sized vertical on 15m azimuth....................................................194 Figure 242 Force-12 Sigma-5 vs. BP full-sized vertical on 15m elevation ..................................................194 Figure 243 Force-12 Sigma-5 vs. BP full-sized vertical on 17m azimuth....................................................195 Figure 244 Force-12 Sigma-5 vs. BP full-sized vertical on 17m elevation ..................................................195 Figure 245 Force-12 Sigma-5 vs. BP full-sized vertical on 20m azimuth....................................................196 Figure 246 Force-12 Sigma-5 vs. BP full-sized vertical on 20m elevation ..................................................196 Figure 247 Comparing various 20m antenna options ...................................................................................197 Figure 248 Force-12 Sigma-5 on 20m over a range of ground types..........................................................200 Figure 249 Full-wave radials used to reduce ground loss............................................................................201 Figure 250 Force-12 Sigma-5 on 10m compares no radials and 16 radials ...............................................202 Figure 251 Force-12 Sigma-5 on 12m compares no radials and 16 radials ...............................................202 Figure 252 Force-12 Sigma-5 on 15m compares no radials and 16 radials ...............................................203 Figure 253 Force-12 Sigma-5 on 17m compares no radials and 16 radials ...............................................203 Figure 254 Varying radial lengths for 16 radials over a vertical dipole........................................................205 Figure 255 Varying radial length for 32 radials over a vertical dipole..........................................................206 Figure 256 Radial length vs. gain for 16 radials under a Force-12 Sigma-5...............................................208 Figure 257 16 radials alternating lengths of 20 feet and 33 feet under Force-12 Sigma-5........................209 Figure 264 Cabela’s 14 foot collapsible panfish pole....................................................................................213 Figure 265 Balcony fishing pole antenna for 20m.........................................................................................214 Figure 266 SWR for 20m fishing pole balcony antenna ...............................................................................215 Figure 267 20m fishing pole balcony antenna 2D far field pattern...............................................................216 Figure 268 20m fishing pole balcony antenna 3D far field pattern...............................................................216 Figure 269 Hentenna for 6m antenna view....................................................................................................217 Figure 270 Hentenna for 6m SWR .................................................................................................................218 Figure 271 6m Hentenna Far Field Plot (3D) ................................................................................................219 Figure 272 Hentenna for 6m Far Field Plot over good ground.....................................................................220

Table 1 Force-12 Sigma-5 loading coil values ................................................................................................48 Table 2 TW Antenna Traveler coil values........................................................................................................63 Table 3 Recipes for Buddipole dipole configurations......................................................................................82 Table 4 Buddipole gain and take-off angle summary....................................................................................190 Table 5 Force-12 Sigma-5 gain comparisons 16 67-foot radials vs. no radials..........................................204 Table 6 Force-12 Sigma-5 gain comparisons 16 33-foot radials vs. no radials ..........................................206


Table 7 Force-12 Sigma-5 computed gains with 16 radials of varying length ............................................207 Table 8 Relative gain (dB) of Force-12 Sigma-5 over 16 radials of various lengths ..................................207 Table 9 Comparing gains for the 16@33-feet and 8@20-feet + 8@33-feet configurations ......................209 Table 10 Comparing gains for the 16@33-feet and 8@24-feet + 8@33-feet configurations ....................211


1

1 THE 100 POUND DXPEDITION

A DXpedition is an expedition for the purpose of communicating long distances with amateur radio (often called DX). The idea of such an adventure is at least 60 years old dating back to the Kon Tiki, the raft used by Norwegian explorer and writer Thor Heyerdahl in his 1947 expedition across the Pacific ocean from South America to Polynesia. That simple QRP transmitter helped the crew keep in contact with civilization throughout their 101 day voyage.

Danny Weil (VP2VB), inspired by the Kon Tiki adventure, was one of the DXpeditioning pioneers making contact with over 100,000 hams around the world on his various trips in his boats YASME and YASME II. The YASME Foundation now assists DXers and DXpeditioners alike by funding scientific and educational projects relating to amateur radio.

Since Danny Weil’s time there have been significant advances in technology and DXpeditioning strategies. The “one man in a boat” has been replaced by cargo containers filled with radios, antennas, computers, coax, and many tons of other equipment. DXpedition teams of 10 to 30 operators are not uncommon. While this has been a boon to those looking for a contact from remote places like Peter I, South Sandwich Island, or Kerguelen, the enormous price-tag associated with such endeavors put it out of reach for all but the most affluent or famous.

The 100 Pound DXpedition is my answer to this situation. It is a return to basics. The idea is this: with just 100 pounds of equipment, one should be able to set up on some far away place and operate a DXpedition. This weight limit imposes an upper-bound on what can be done. For example, some of the larger DXpeditions try to separate antennas by 1000 or 1200 feet. The weight of 1000 foot of RG-213 coax is about 104 pounds—four pounds over the limit for all equipment on a 100 Pound DXpedition!

As artists sometimes say, “Form is freeing.” That is to say that limits help bring focus and illuminate possibilities. With such draconian weight limits you cannot be tempted to bring the big amplifier, tower sections, or huge antennas. Instead, you can begin to research compromises and trade-offs, see what works and what does not, and determine for yourself what is key, what is extra, what is signal and what is noise. In a permanent station you might fight for every dB. But, when every pound counts, do you trade 2 dB for 12 extra pounds? These thinking processes are at the very heart of a 100 Pound DXpedition.

Finally, with these limits come rewards. Traveling so light means you and your portable station are just a plane ride away from very interesting places. The 100 pound limit fits within many airline guidelines so a DXpedition can be done by packing, checking your bags, and finding your seat. There are no cargo containers. There are no tedious logistics and freight plans. You can just go, unpack, set up, and have fun.

The remainder of this white paper discusses the antenna aspects of a 100 Pound DXpedition.

Again, we are not looking for the biggest and best; we are looking for the best “bang for our buck” and best “power per pound.” Welcome to lightweight DXpeditioning.


2

2 ANTENNA ASPECTS OF DXPEDITIONING

Preparing an antenna for your home station may involve weeks or months of planning and execution. Erecting a tower, for example, may involve obtaining permits from your community’s planning board, digging the footing, filling it with rebar and concrete, and waiting a month for that concrete to cure. Only then can you attach the tower and begin thinking about hoisting the antennas to height.

The weight of an antenna system for a home station is rarely of concern except perhaps for the shipping charges for the delivery of the parts. Heavy tower sections or antennas are a minor inconvenience if they require extra hands during assembly. And, once a system is assembled we are rarely interested in how easily it can be disassembled and shipped again.

Antennas for DXpeditioning violate many of the assumptions that we might have for antennas in our home station. We care about their weight. We care about assembly and disassembly time and complexity. The antennas must be assembled, disassembled, and shipped repeatedly for us to get value from them.

Put more starkly: it doesn’t matter if an antenna performs well if you can’t bring it. Antennas that are too heavy, too complicated, require hefty support structures, or cannot be broken into small (48 inch) pieces cannot be considered for this use. If you plan a trip for a week to some beautiful destination, you cannot afford to spend two days assembling antennas and another disassembling them. Antennas that require that kind of investment might make fine home station antennas, but they are all but useless for lightweight DXpeditioning.

The baggage allowances set by airlines provide a general guideline for the physical dimensions of the antennas we can consider. These allowances are typically:

• Two checked bags. Some airlines allow three bags (such as Southwest), but the general allowance is two bags for most US carriers. In this age of high fuel prices, some carriers are now charging a fee for the second and even first checked bag. Still, it is a reasonable assumption that two checked bags can be brought without excessive charges.

• Fifty pounds per bag. Some airlines are more lax on this point than others. You can also pay to have your bag accepted for weights up to 70 or even 100 pounds. This is helpful when you may be living within the 100 pound combined limit, but one bag is heavier than another.

• Size of 62 linear inches. The combined height plus width plus depth of a bag cannot exceed 62 inches. The Pelican 1610 case is one of the largest cases that satisfies this requirement.

• Golf and sports bags. There is an exception to the above rules for sports enthusiasts, or at least those of us who use similar equipment. Golf bags, ski bags, and similar equipment bags are exempted from the size restriction and sometimes from the weight restriction.

These are general guidelines. Check with your carrier for the specific rules of your airline.


3

A reasonable strategy is to have one hard-sided golf bag for long antenna parts, coax, and other parts, and have a second hard-sided case for the radio, tuner, power supply, and other smaller parts. A third carry-on bag can then hold clothes and other personal items. Remember, you need to count the weight of the equipment and the weight of the bags when budgeting!

Here are some things we look for when making antenna selection for lightweight DXpeditions:

• Size – This is even more important than weight in some respects. A golf bag will typically accommodate pieces 48 inches in length. If it cannot fit in the bag, it cannot go. So, even very light antennas with 72 inch parts (6 foot lengths) are not useful for our purposes.

• Weight – We have a total weight budget of 100 pounds but can divide this between all the equipment in whatever fashion we like. If we wish to bring more radio gear, we will likely need to bring fewer antenna pieces. Similarly, if we bring larger, heavier, or bulkier antennas, we may have to bring fewer or lighter other items to compensate. Weight is always a trade-off in these calculations.

• Ease of assembly and disassembly – Some antennas are designed to be assembled once and never disassembled. The use of pop-rivets would be an example of an antenna design decision that would hint at this. The best lightweight DXpedition antennas are ones that can be assembled easily, disassembled easily, and packed easily. Custom bags, containers, and packing materials that would never see use for a home station antenna can be extremely beneficial for a DXpedition antenna.

• Multiple band use – This is not a requirement, but it can be very helpful to have an antenna that is effective on multiple bands. There are two reasons for this:

o Multi-band antennas may reduce the deployment time for your antenna systems. For example, if you assemble a 40m antenna that is also effective on 15m, this means you do not need to assemble a specific 15m antenna. Also, trapped verticals or triband yagis provide multiple bands but may not be more complicated or time-consuming to assemble than a similarly designed single-band antenna. The time savings can mean more operating or leisure time in that exotic location.

o Multi-band antenna systems require only one run of coax – This is almost trivial for home stations but quite important for a lightweight DXpedition. A discussion of coax trade-offs may be found later in this paper.

• The antenna’s physical footprint – Depending on your DXpedition’s destination, there may not be much room to erect antennas. In such cases, antennas with smaller footprints may be more desirable than larger ones. For example, a -wave vertical requires radials. If there is no room to run these radials, however, you’ve got a problem. A half-wave vertical dipole does not need radials and can be erected in a very small area. Vertical dipoles have other disadvantages such as being taller (in general) and more difficult to feed (since the feed point is higher and the feed line must be routed carefully to avoid parasitic coupling).


4

• The antenna’s visual footprint – Unless you are isolated from others, erecting large, ugly antenna systems may be frowned upon by your neighbors. You will need to select an antenna compliment that is “compatible with the neighborhood.”

The antennas discussed in this white paper conform to these guidelines to varying degrees. Evaluating the antennas is not a straightforward task either for the criteria above, or for performance in the field. Perhaps the criteria above can be used to provide guidance as to whether an antenna is eligible for this service and other criteria can determine its performance in this service.

Few things get amateur radio operators more wound-up than antenna performance discussions. So, let me say this before anything else is presented:

Everything in this white paper is wrong to some degree.

In the sciences like physics and chemistry there is a notion of experimental error. The experiment may be intentionally flawed to take advantage of significant simplifications. Results may therefore be representative, but not numerically precise. There is also the concept of measurement error. Even when precise measurements are taken there will always be variations and precision limitations. There will be a great deal of both types of errors in what follows. If this makes you uncomfortable, stop reading now.

I will be discussing antenna products and antenna designs that I have used, or considered using, on lightweight DXpeditions. I have spent the last few years gathering practical experience with these antennas and have now augmented that with computer models. These models, although they use software that has a surprising mathematical precision, are approximations of the actual antenna system. First, some antennas are described using only approximate dimensions for element lengths, element diameters, materials, or the placement of certain junctions. In some cases the imprecision is because these small differences make the model much easier to construct or because of the limitations of the modeling engine. Other justifications for this imprecision are more easy to explain: I do not own the antenna in question and have made only guesses (though well-reasoned guesses, to be sure) of some of the values. Finally, never discount the possibility that I just measured wrong, entered the data wrong, or otherwise goofed.

Rather than defend every number abstractly I will discuss every choice and every method used to create the models. I’ll show the results from the modeling and compare it, where possible, to practical experience I have had with the antenna. I will also include details of the model files so everyone can execute these models and check the inputs and results for themselves. I have found this research to be helpful for my planning and my trips. I hope they will be as helpful to others.


5

3 SOME NOTES ON MODELING

The following models were created with EZNEC 5 from W7EL. This is an extremely powerful piece of software and I can only hope to master some of it over the next few years. Luckily, my immediate needs for this analysis only require understanding the basics of the program.

Antenna modeling software provides very accurate computations and results based on the input it receives. That said, this software cannot overcome bad input. If the model is wrong, the answer will likely be at least as wrong. But, to put this into perspective, consider these words:

“Essentially, all models are wrong, but some are useful.”

George Box, Professor Emeritus of Statistics at the University of Wisconsin

There are some small compromises in the placement of antenna elements in these models because of limitations in the modeling software. I believe the errors induced by these small changes will not adversely affect the results. There are other small compromises in measurements that have been made to make the models simpler (and the life of the modeler easier). Again, I believe that these small compromises still provide modeling results that are representative of the behavior and performance of the device modeled. The model descriptions for each antenna contain notes that describe such compromises when they have been made.

There are things that are difficult to specify. The effects of ground are quite important to many antenna systems and yet this data is difficult to specify with any accuracy. To accommodate this, I provide several runs of computation and output for both good ground and very poor ground. An example of good ground is pastoral ground; an example of poor ground is a city lot. EZNEC provides mappings of these concepts to numeric values used in its calculations. The performance in any particular situation will likely be between those two extremes

Finally, a model is not the thing you are modeling. I will, where possible, provide completely subjective commentary relating to my experience with each antenna. As the common modern day lament goes, “your mileage may vary.” Before we begin with some antennas that we will use as “reference” antennas we shall have a brief discussion about physical measurements.


6

4 PHYSICAL MEASUREMENT

Modeling was done with EZNEC. Direct measurements of some antenna systems were done with the AntennaSmith by Time Wave. (http://timewave.com). A picture of this unit appears below.

Figure 1 AntennaSmith by Time Wave

This device not only measures SWR and other characteristics of an antenna system but also provides plots of this data over specified ranges. Two types of these plots appear below.

SWR plot on AntennaSmith Smithchart plot on AntennaSmith

Figure 2 On-screen plots viewed on the AntennaSmith

Software accompanying the unit provides for the upload of data and plots to a PC. Where possible, direct measurements have been taken of these antenna systems and these direct measurements appear next to predicted values from our modeling.


7

5 REFERENCE ANTENNAS

Before we begin investigating the performance of antennas we might use on a 100 Pound

DXpedition we should look at the performance of some standard antenna designs. (Note that these standard antenna designs may also make fine antennas for our purposes!) This will give us a baseline from which we might compare antennas. The two antenna types to be discussed are a

• Quarter wave vertical antenna – This is a ground mounted antenna fed about 29 inches above ground with 16 radials.

• Vertical dipole antenna – This is an antenna that does not require a radial system, is center fed, and can be deployed in even small areas.

An antenna of each type is modeled for all five bands 10, 12, 15, 17, and 20 meters. We begin with the quarter-wave vertical.

5.1 Quarter-wave verticals

The following antennas are modeled with simple runs of AWG 16 wire. Antennas serving bands 10-20 meters such antennas can be easily constructed with a simple fishing pole holding up the vertical element and radials tied to trees or stakes. Though presented here as a “reference” antenna, these antennas could be used on a 100 Pound DXpedition. The space required to fully deploy the antennas is greater than what we typically expect to have, but if the space is available these antennas are fine choices giving good value for weight, size, and performance.

I have used a “fishing pole vertical” for 40 meters (which is also good on 15 meters) and 80 meters on several trips with only two elevated radials with very good results. Since 20-foot fishing poles are available from major sporting good outlets for very little money, these antennas are also a very cost effective way to get on the air in that remote location.

The following reference antennas are shown with 16 radials. Even four radials provide a surprisingly good antenna. The reader is encouraged to model these antennas for themselves. In the mean time, we spend the next few sections discussing these simple antennas for 10 through 20 meter bands.

5.1.1 10 meter Quarter-wave Vertical with Radials

A full-sized quarter-wave vertical with radials is one of the simplest antennas to make or model. This example is a 10m vertical antenna with 16 radials. The antenna is fed, and its radials emanate from, a height of 29 inches. This puts the top of the antenna about 12 feet off the ground, easily held by a modestly sized collapsible fishing pole. A Black Widow pole 13 foot in length (with a closed length of 45.5 inches) is less than $11, for example. Longer poles up to 20 feet cost under $20. Such poles would make fine masts to hold up the upper-end of one of these quarter wave verticals.

The model image for this antenna appears below.


8

Figure 3 Full-sized 10m quarter-wave vertical

This is a pretty good antenna and it is very simple. The EZNEC model description for it follows.

EZNEC+ ver. 5.0

Quarter-wave vertical for 10m 8/31/2007 10:46:00 AM

--------------- ANTENNA DESCRIPTION ---------------

Frequency = 28.3 MHz

Wire Loss: Copper -- Resistivity = 1.74E-08 ohm-m, Rel. Perm. = 1

--------------- WIRES ---------------

No. End 1 Coord. (in) End 2 Coord. (in) Dia (in) Segs

Insulation

Conn. X Y Z Conn. X Y Z Diel C Thk(in)

1 W2E1 0, 0, 29 0, 0, 132 #16 6 1 0

2 W3E1 0, 0, 29 0, 103, 29 #16 6 1 0

3 W4E1 0, 0, 29 -39.416,95.1596, 29 #16 6 1 0

4 W5E1 0, 0, 29 -72.832, 72.832, 29 #16 6 1 0

5 W6E1 0, 0, 29 -95.16,39.4164, 29 #16 6 1 0

6 W7E1 0, 0, 29 -103, 0, 29 #16 6 1 0

7 W8E1 0, 0, 29 -95.16,-39.416, 29 #16 6 1 0

8 W9E1 0, 0, 29 -72.832,-72.832, 29 #16 6 1 0

9 W10E1 0, 0, 29 -39.416, -95.16, 29 #16 6 1 0

10 W11E1 0, 0, 29 0, -103, 29 #16 6 1 0

11 W12E1 0, 0, 29 39.4164, -95.16, 29 #16 6 1 0

12 W13E1 0, 0, 29 72.832,-72.832, 29 #16 6 1 0

13 W14E1 0, 0, 29 95.1596,-39.416, 29 #16 6 1 0

14 W15E1 0, 0, 29 103, 0, 29 #16 6 1 0

15 W16E1 0, 0, 29 95.1596,39.4165, 29 #16 6 1 0

16 W17E1 0, 0, 29 72.832, 72.832, 29 #16 6 1 0

17 W1E1 0, 0, 29 39.4164,95.1596, 29 #16 6 1 0

Total Segments: 102


9

-------------- SOURCES --------------

No. Specified Pos. Actual Pos. Amplitude Phase Type

Wire # % From E1 % From E1 Seg (V/A) (deg.)

1 1 0.00 8.33 1 1 0 I

No loads specified

No transmission lines specified

No transformers specified

No L Networks specified

Ground type is Real, High-Accuracy

--------------- MEDIA ---------------

No. Cond. Diel. Const. Height R Coord.

(S/m) (in) (in)

1 0.005 13 0 0

This model yields the following SWR plot. (All SWR plots for antennas in this white paper are for antennas operated over “good” ground.)

Figure 4 SWR for quarter wave vertical on 12m

The plots for this antenna over good ground appear below.


10

10m quarter-wave vertical 10m quarter-wave vertical

Figure 5 Quarter wave vertical on 10m over good ground

The plots for the same antenna over poor ground appear below.


Figure 6 Quarter wave vertical on 10m over poor ground

This pattern of plots is repeated throughout this white paper. A diagram or photograph of the antenna system discussed is presented. Modeling information along with SWR plots come next. Then, far-field plots showing the antenna performance over both a good ground and over a poor ground are shown. This presentation provides an excellent overview of the


11

antenna and its performance. The modeling input data additionally provides a means for the reader to perform these calculations themselves and possibly further alter the simulated environment to learn more.

The ARRL Antenna Book is an excellent resource for anything relating to amateur radio antennas. It is also recommended that the reader study the relevant sections of that reference work for any particular antenna type discussed here (vertical monopole, vertical dipole, etc.). Such reading will help set reasonable expectations for each antenna type. For example, this antenna presents about 30 ohms of R, not 50 ohms. This is expected in a vertical monopole with a good radial system.

The far-field plots have a great deal of information within them. The general shape of the azimuth plot shows the relative strength of the signals emitted in any given direction. These relative strengths are normalized to the 0 dB outer ring and directions where the signal is less than the maximum appear plotted within the circle intersecting with graphed rings of -5 dB, -10 dB, etc.

The elevation plot provides an indication of the angles where most of the radiation is being emitted. This simple vertical monopole has only one lobe but other antennas may have several lobes and deep nulls between them. Those deep nulls would indicate angles where little or no radiation is emitted. The large lobes would represent the antenna’s “take off angle”, the angle from which the most radiation is emitted or received.

Though the relative shapes of the plots for good ground and poor ground may appear similar, the magnitude of the radiation represented by the outer ring may be vastly different. In this case, the outer ring for the good ground plot represents 0.33 dBi; the outer ring for the poor ground plot represents -0.2 dBi. In other antenna systems the effects of ground on antenna efficiency are more pronounced.

Finally, the effects of ground can also affect the antenna’s take off angle. Generally, better ground lowers the take off angle. This is a problem for two reasons: (1) some of the more interesting and fun places to visit have sandy soil and provide a very poor ground, and (2) these interesting places are typically far away from stations we would like to work so a low take off angle is especially important. There is a discussion about the effects of ground, and things that might be done to manage it, later in the paper.

This system of diagrams for SWR and far-field plots provides some visual means of comparing antenna systems to a standard set of antennas and to each other. A significant amount of space is dedicated to these comparisons later in this paper.


12


This example is a 12m vertical antenna with 16 radials. Like the 10m vertical described above, this one is also mounted with the feed point 29 inches above ground.


The model description data is shown below.

EZNEC+ ver. 5.0

Fishing pole vertical for 12m 8/31/2007 10:30:18 AM

--------------- ANTENNA DESCRIPTION --------------


Wire Loss: Copper -- Resistivity = 1.74E-08 ohm-m, Rel. Perm. = 1 -----------

---- WIRES ---------------

No. End 1 Coord. (in) End 2 Coord. (in) Dia (in) Segs Ins


1 W2E1 0, 0, 29 0, 0, 145 1 6 1 0

2 W3E1 0, 0, 29 0, 141, 29 #16 6 1 0

3 W4E1 0, 0, 29 -53.958,130.267, 29 #16 6 1 0

4 W5E1 0, 0, 29 -99.702,99.7021, 29 #16 6 1 0

5 W6E1 0, 0, 29 -130.27,53.9583, 29 #16 6 1 0

6 W7E1 0, 0, 29 -141, 0, 29 #16 6 1 0

7 W8E1 0, 0, 29 -130.27,-53.958, 29 #16 6 1 0

8 W9E1 0, 0, 29 -99.702,-99.702, 29 #16 6 1 0

9 W10E1 0, 0, 29 -53.958,-130.27, 29 #16 6 1 0

10 W11E1 0, 0, 29 0, -141, 29 #16 6 1 0

11 W12E1 0, 0, 29 53.9584,-130.27, 29 #16 6 1 0

12 W13E1 0, 0, 29 99.702,-99.702, 29 #16 6 1 0

13 W14E1 0, 0, 29 130.267,-53.958, 29 #16 6 1 0

14 W15E1 0, 0, 29 141, 0, 29 #16 6 1 0

15 W16E1 0, 0, 29 130.267,53.9584, 29 #16 6 1 0

16 W17E1 0, 0, 29 99.7021, 99.702, 29 #16 6 1 0


13

17 W1E1 0, 0, 29 53.9583,130.267, 29 #16 6 1 0

Total Segments: 102

-------------- SOURCES --------------



1 1 0.00 8.33 1 1 0 I

No loads specified





--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.005 13 0 0

This yields an SWR curve as shown below.


The plots for this antenna over good ground appear below.


14







15


This example is a 15m vertical antenna with 16 radials at 29 inches. The model view of this antenna appears below.


The model data for this antenna is shown below.

EZNEC+ ver. 5.0

Quarter wave vertical for 15m 8/31/2007 11:26:14 AM




--------------- WIRES ---------------



1 W2E1 0, 0, 29 0, 0, 167 #16 6 1 0

2 W3E1 0, 0, 29 0, 134, 29 #16 6 1 0

3 W4E1 0, 0, 29 -51.28, 123.8, 29 #16 6 1 0

4 W5E1 0, 0, 29 -94.752,94.7524, 29 #16 6 1 0

5 W6E1 0, 0, 29 -123.8,51.2795, 29 #16 6 1 0

6 W7E1 0, 0, 29 -134, 0, 29 #16 6 1 0

7 W8E1 0, 0, 29 -123.8, -51.28, 29 #16 6 1 0

8 W9E1 0, 0, 29 -94.752,-94.752, 29 #16 6 1 0

9 W10E1 0, 0, 29 -51.28, -123.8, 29 #16 6 1 0

10 W11E1 0, 0, 29 0, -134, 29 #16 6 1 0

11 W12E1 0, 0, 29 51.2796, -123.8, 29 #16 6 1 0

12 W13E1 0, 0, 29 94.7523,-94.752, 29 #16 6 1 0

13 W14E1 0, 0, 29 123.8, -51.28, 29 #16 6 1 0

14 W15E1 0, 0, 29 134, 0, 29 #16 6 1 0

15 W16E1 0, 0, 29 123.8,51.2797, 29 #16 6 1 0


16

16 W17E1 0, 0, 29 94.7524,94.7523, 29 #16 6 1 0

17 W1E1 0, 0, 29 51.2795, 123.8, 29 #16 6 1 0

Total Segments: 102

-------------- SOURCES --------------



1 1 0.00 8.33 1 1 0 I

No loads specified





--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.005 13 0 0

This antenna yields the following SWR plot.



17







18


This example is a 17m vertical antenna with 16 radials at 29 inches. The model view for this antenna appears below.


The model data for this antenna appears below.

EZNEC+ ver. 5.0

Quarter wave vertical for 17m 8/31/2007 2:02:43 PM




--------------- WIRES ---------------

No. End 1 Coord. (in) End 2 Coord. (in) Dia (in) Segs Insu


1 W2E1 0, 0, 29 0, 0, 191 #16 6 1 0

2 W3E1 0, 0, 29 0, 158, 29 #16 6 1 0

3 W4E1 0, 0, 29 -60.464,145.973, 29 #16 6 1 0

4 W5E1 0, 0, 29 -111.72,111.723, 29 #16 6 1 0

5 W6E1 0, 0, 29 -145.97,60.4639, 29 #16 6 1 0

6 W7E1 0, 0, 29 -158, 0, 29 #16 6 1 0

7 W8E1 0, 0, 29 -145.97,-60.464, 29 #16 6 1 0

8 W9E1 0, 0, 29 -111.72,-111.72, 29 #16 6 1 0

9 W10E1 0, 0, 29 -60.464,-145.97, 29 #16 6 1 0

10 W11E1 0, 0, 29 0, -158, 29 #16 6 1 0

11 W12E1 0, 0, 29 60.464,-145.97, 29 #16 6 1 0

12 W13E1 0, 0, 29 111.723,-111.72, 29 #16 6 1 0

13 W14E1 0, 0, 29 145.973,-60.464, 29 #16 6 1 0


19

14 W15E1 0, 0, 29 158, 0, 29 #16 6 1 0

15 W16E1 0, 0, 29 145.973,60.4641, 29 #16 6 1 0

16 W17E1 0, 0, 29 111.723,111.723, 29 #16 6 1 0

17 W1E1 0, 0, 29 60.4639,145.973, 29 #16 6 1 0

Total Segments: 102

-------------- SOURCES --------------



1 1 0.00 8.33 1 1 0 I

No loads specified





--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.001 3 0 0

This model yields an SWR plot as follows.


The far-field plot for this antenna over good ground appears below.


20



The far-field plot for this antenna over poor ground appears below.




21


This example is a 17m vertical antenna with 16 radials at 29 inches. The model view of this antenna appears below.


The model data for this antenna is found below.

EZNEC+ ver. 5.0

Quarter wave vertical for 17m 8/31/2007 2:27:48 PM




--------------- WIRES ---------------

No. End 1 Coord. (in) End 2 Coord. (in Dia (in) Segs Ins


1 W2E1 0, 0, 29 0, 0, 235 #16 6 1 0

2 W3E1 0, 0, 29 0, 201, 29 #16 6 1 0

3 W4E1 0, 0, 29 -76.919, 185.7, 29 #16 6 1 0

4 W5E1 0, 0, 29 -142.13,142.129, 29 #16 6 1 0

5 W6E1 0, 0, 29 -185.7,76.9193, 29 #16 6 1 0

6 W7E1 0, 0, 29 -201, 0, 29 #16 6 1 0

7 W8E1 0, 0, 29 -185.7,-76.919, 29 #16 6 1 0

8 W9E1 0, 0, 29 -142.13,-142.13, 29 #16 6 1 0

9 W10E1 0, 0, 29 -76.919, -185.7, 29 #16 6 1 0

10 W11E1 0, 0, 29 0, -201, 29 #16 6 1 0

11 W12E1 0, 0, 29 76.9194, -185.7, 29 #16 6 1 0

12 W13E1 0, 0, 29 142.128,-142.13, 29 #16 6 1 0

13 W14E1 0, 0, 29 185.7,-76.919, 29 #16 6 1 0


22

14 W15E1 0, 0, 29 201, 0, 29 #16 6 1 0

15 W16E1 0, 0, 29 185.7,76.9195, 29 #16 6 1 0

16 W17E1 0, 0, 29 142.129,142.128, 29 #16 6 1 0

17 W1E1 0, 0, 29 76.9193, 185.7, 29 #16 6 1 0

Total Segments: 102

-------------- SOURCES --------------



1 1 0.00 8.33 1 1 0 I

No loads specified





--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.005 13 0 0

This model yields the following SWR plot.




23







24

5.2 Half-wave vertical dipoles

Half-wave vertical dipole antennas are what the name describes: a dipole turned on its side so it is oriented vertically. A full-sized vertical dipole also makes a good basis for subsequent comparisons. This antenna has the advantage of having a smaller footprint than a vertical monopole antenna because it does not require radials. However, it is twice as tall as the quarter-wave antenna and the feed line must be routed away from the antenna carefully to avoid parasitic coupling.

Half-wave vertical dipoles were used with very good results by the Microlite Penguin DXpedition team on South Sandwich Island and other places. In addition to being a good radiator, pairs of vertical dipoles can work together to provide gain in one direction or another. Visualize a Yagi turned on its side to get the idea. A passive element can be placed as either a reflector or director for the driven element. If the passive unit is equipped with a switch to change the length of the elements then the switched vertical dipole antenna (SVDA) can be aimed one of two directions, depending on the state of the switch. Since this passive element could be constructed with a fishing pole and lightweight wire, it is an easy “throw in” for a 100 Pound DXpedition.

The following sections provide models for full-size half-wave vertical dipole antennas. Comparing the results of these antennas to the quarter-wave verticals shows that the vertical dipoles have slightly more gain, a slightly lower take-off angle, and are somewhat more immune to the effects of ground.

5.2.1 Full-sized 10 Meter Vertical Dipole

Here is a view of the full-sized vertical dipole for 10 meters. A model view of this antenna appears below. For these antenna models the bottom of the vertical dipole is at 29 inches with the feed point much higher.

Figure 23 View of the full-sized 10 meter vertical dipole

The EZNEC model description for the full-sized 10m vertical dipole appears below:

EZNEC+ ver. 5.0

Full-size 10m vertical dipole 8/28/2007 11:42:06 PM




25


--------------- WIRES ---------------


Insulation


1 0, 0, 29 0, 0, 225 1 11 1 0

Total Segments: 11

-------------- SOURCES --------------



1 1 50.00 50.00 6 1 0 I

No loads specified





--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.005 13 0 0

This model produces the following SWR plot.

Figure 24 SWR for half wave vertical dipole on 10m


26

The far-field plot for this antenna appears below. Note that the elevation plot shows a much lower take off angle for the vertical dipole when compared to that of the vertical monopole. The outer ring represents 0.76 dBi in these plots. The monopole had an outer ring value of 0.33 dBi. Elevating the feed point and radiator lowered the take-off angle and increased gain slightly.

Half-wave vertical dipole on 10m Half-wave vertical dipole on 10m

Figure 25 Half-wave vertical dipole on 10m over good ground

Below are the plots for poor ground. Note that the outer ring represents 0.61 dBi in these plots over poorer ground, 0.1 dB down from the good ground plot, but far less of a degradation than that observed when we moved a quarter wave monopole from good ground to poor ground. Except for a slight reduction in overall gain, the antenna performed about as well over poor ground as it did over good ground. This is most likely due to getting the feed point of the antenna well away from the lossy ground.

Half wave vertical dipole (HWVD) antennas are a fine choice for 100 Pound DXpeditions because they are relatively easy to erect, have a small footprint, and are relatively immune to the poor sandy ground of islands and beaches (places attractive for our lightweight DXpeditions). A 40m antenna is unwieldy at 66 to 70 feet, but antennas for bands 10-15m are very practical, light, and easy to deploy.


27


Figure 26 Half-wave vertical dipole on 10m over poor ground


Here is a view of the full-sized vertical dipole for 12 meters with its base at 29 inches.


The EZNEC model description for the full-sized 12m vertical dipole appears below.

EZNEC+ ver. 5.0





--------------- WIRES ---------------

No. End 1 Coord. (in) End 2 Coord. (in) Dia (in) Segs Insulation



28

1 0, 0, 29 0, 0, 256 1 11 1 0

Total Segments: 11

-------------- SOURCES --------------



1 1 50.00 50.00 6 1 0 I

No loads specified





--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.005 13 0 0




29







30


Here is a view of the full-sized vertical dipole for 15 meters with the base at 29 inches.



EZNEC+ ver. 5.0





--------------- WIRES ---------------



1 0, 0, 29 0, 0, 295 1 11 1 0

Total Segments: 11

-------------- SOURCES --------------



1 1 50.00 50.00 6 1 0 I

No loads specified





--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.005 13 0 0



31




32



The far field plot for this antenna over poor ground appears below.




33




The EZNEC model description for the full-sized 17m vertical dipole appears below.

EZNEC+ ver. 5.0


-------------- ANTENNA DESCRIPTION ---------------



--------------- WIRES ---------------



1 0, 0, 29 0, 0, 341 1 11 1 0

Total Segments: 11

-------------- SOURCES --------------



1 1 50.00 50.00 6 1 0 I

No loads specified





--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.005 13 0 0



34




35







36





EZNEC+ ver. 5.0





--------------- WIRES ---------------



1 0, 0, 29 0, 0, 430 1 11 1 0

Total Segments: 11

-------------- SOURCES --------------



1 1 50.00 50.00 6 1 0 I

No loads specified





--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.005 13 0 0

This model yields an SWR plot as follows.


37




38







39

6 FORCE-12 SIGMA-5 ANTENNA

The Force-12 Sigma-5 antenna is a five-band antenna. The antenna will be treated as five different antennas for our discussion starting with the antenna on 10 meters. I have used this antenna on brief stints on Georges Island (NA-148) in Boston Harbor, among other places, and have found it to be surprisingly good for its size.

The phrase “surprisingly good for its size” is suspect, of course. Rather than provide vague assurances that this device is not a dummy load direct mathematical comparisons will be made between this antenna and others. Those results should sway the reader to also say “surprisingly good for its size.”

The other aspect of our analysis is subjective. This unit weighs about eight pounds and requires a single piece of coax for the five bands it services. Assuming the weight of RG-8X is about 2 pounds for a 50 foot length, we can service five bands with a single 2 pound run instead of feeding 5 different antennas with a total of 10 pounds of coax. Not only is the antenna reasonably light, but the multiple bands also saved 8 pounds of coax from our weight budget! Is that worth a dB? Is that worth 1.5 dBs? These are questions to be asked when planning every trip.

The drawbacks of the Force-12 Sigma-5 are two: though it does break down into sections about 2 feet in length, the center section with its controller is bulky and difficult to pack easily. Additionally, the coils within the controller, especially the 20-meter coils, need to be adjusted after travel as they are not rigid and can change shape when jostled. Still, if you can find a way to pack it and do not mind doing a quick adjustment once you reach your destination, this is an interesting antenna design.

6.1 Force-12 Sigma-5 on 10 meters

The Force-12 Sigma-5 is a shortened half-wave vertical antenna with a matching box that allows operations on five bands: 10, 12,15,17, and 20 meters. The antenna breaks down into roughly 2-foot pieces and stands about 9 feet tall when assembled.


40

Figure 43 The assembled Force-12 Sigma-5

The basic structure of the antenna is that of a vertical dipole with capacity hats on both ends. The 21st edition of the ARRL Antenna Book describes this design as a Compact Vertical

Dipole though that text was for a single-band design. The multi-band design of the Sigma-5 begins with a full-sized 10m antenna and adds loading coils to provide a match on the other bands. Relays controlled by a remote switch engage these coils as needed. The coils, relays, and matching system are housed in a plastic enclosure at the center of the antenna. The figure below shows the circuit board and coils for this unit.


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Figure 44 Force-12 Sigma-5 matching circuit

The feed line and control cable come in from the top of the picture. Ferrite surrounds those lines to help reduce common-mode currents. The circuit board has coils on the top-side (shown) and relays on the bottom (not shown). The control cable is used to energize relays and select the coils to be used for loading the antenna.

Starting from the center of the circuit board and moving out we find:

• The matching stub / coil – This coil is copper in color and provides a matching stub for the antenna.

• The 12m matching coil – On either side of the matching stub are two widely spaced coils used to load the antenna on 12 meters.

• The 15m matching coil – The tightly wound coils after the 12m coils are used to load the antenna for 15 meters. Note that the 15-meter band is selected by including both the 12m coil and 15m coils.

• The 17m matching coil – The next set of coils are for 17 meters. This band is matched with the 12m, 15m, and 17m coils in series.

• The 20m matching coil – The coils found nearest the ends of the circuit board are for 20 meters. All four coils (12m, 15m, 17m, and 20m) are in series to provide a match on this band.

If no relays are energized then all coils are active and the antenna can be used on 20 meters. Other bands are selected by energizing particular relays that bypass one or more coils. The


42

modeling description section describes how the lengths of aluminum and coils are measured and placed within the model.

6.1.1 Model description

There are three things that need to be specified for this model: the dimensions of the aluminum structure for the antenna, the values and placement of the coils and matching stub, and the type of ground beneath the antenna. Each of these will be addressed in turn.

The antenna consists of two sizes of aluminum tubing: 1 inch and 0.5 inch stock. The vertical element is one inch in diameter; the arms of the capacity hat are 0.5 inches. The modeling software was having trouble with the connections of the half-inch arms to the one inch vertical section so I made a small alteration in the description. Both ends of the tall vertical radiator are now only a half-inch in diameter matching the arms. The impact on the computations should be minimal and this made the modeling program happy.

Main length is 1.0 inches in diameter

Last 6 inches are 0.5 inches in diameter

Arms are 0.5 inches in diameter

Figure 45 Force-12 Sigma-5 element diameters

The modeling program also assumes that the driven element is one continuous wire with the feed point connected to a particular segment. The actual antenna has two separate pieces of aluminum for the top and bottom elements with some separation between them. I have combined those two aluminum elements into one for the model. Further, the feed point was specified to be “50% from end 1” but the actual position selected by the program is slightly off from that (due to the requirement that the feed point be placed at a segment junction).

The model is made of wires and loads. (Wires can be thin wires or big aluminum tubes.) This model has seven wires: four arms of the upper and lower capacity hat, and three


43

elements in the vertical section, two six inch pieces at the top and bottom, and the main one inch diameter tube. The assembled antenna is 103 inches high with the lower arms 29 inches off the ground when mounted on the insulated post packaged with the antenna. Each of the arms are 24 inches in length. There is a small amount of one inch tubing along the vertical axis at both the top and bottom of the antenna that is ignored in the model. These dimensions are sufficient to produce a wire list for our model.

The coils of the model require slightly more work to fully characterize. Using a ruler, I measured the diameter, length, and number of turns for each of the coils in the unit. With this information an approximation can be made of the inductance of the coil using the following formula:

where L( H) is the inductance of the coil, d is the diameter of the coil in inches, n is the number of turns in the coil, and l is the length of the coil in inches.

The large capacity hats on both ends of the dipole will generate a large capacitive reactance in-line with the other resistances presented at the feed point of the antenna. To counteract this excess capacitance, an inductor across the feed point providing an equal and opposite reactance will be necessary. This is a stub. The stub for this antenna was measured and calculated as per the table below:

Name Diameter Number of turns Length XL

Stub 1.5 4 1 0.53 H

This matching stub is present for all bands, not just the 10 meter band.

If the model were a prefect then the antenna would be a good match on 10 meters with just this in place. For whatever reason, we need to add just a bit of inductance to load each side of the dipole to make this happen. (This is likely due to the fact that there are traces on the circuit board and routing around and through relays that have added some small amount of inductance to our system.) A loading coil with an inductive value of 0.3 H was added to the model to bring the SWR into a reasonable range. With this extra inductance we get the following model description of the antenna for EZNEC.

EZNEC+ ver. 5.0

Force-12 Sigma-5 ~ 10m config 8/28/2007 7:47:17 PM



Wire Loss: Aluminum (6061-T6) -- Resistivity = 4E-08 ohm-m, Rel. Perm. = 1

--------------- WIRES ---------------


Insulation


L( H) = d2 n2

18 d + 40 l


44

1 W4E1 0, 0, 29 W2E1 0, 0, 35 0.5 6 1 0

2 W1E2 0, 0, 35 W3E1 0, 0, 126 1 22 1 0

3 W2E2 0, 0, 126 W6E1 0, 0, 132 0.5 6 1 0

4 W5E1 0, 0, 29 0, -24, 29 0.5 6 1 0

5 W1E1 0, 0, 29 0, 24, 29 0.5 6 1 0

6 W7E1 0, 0, 132 0, -24, 132 0.5 6 1 0

7 W3E2 0, 0, 132 0, 24, 132 0.5 6 1 0

Total Segments: 58

-------------- SOURCES --------------



1 2 50.00 52.27 12 1 0 I

-------------- LOADS (RLC Type) --------------

No. Specified Pos. Actual Pos. R L C R Freq Type

Wire # % From E1 % From E1 Seg (ohms) (uH) (pF) (MHz)

1 2 47.00 47.73 11 Open 0.3 Open 28.3 Par

2 2 55.00 56.82 13 Open 0.3 Open 28.3 Par

3 2 50.00 52.27 12 Short 0.52 Short 0 Ser





--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.005 13 0 0

This description results in the antenna view shown in Figure 46 EZNEC antenna view of Sigma-5.


45

Figure 46 EZNEC antenna view of Sigma-5

6.1.2 Analysis

The antenna model now provides a nice match over the entire 10-meter band as shown in the figure below.

SWR predicted by model SWR measured by AntennaSmith

Figure 47 SWR for Force-12 Sigma-5 on 10 meters

The SWR curves above were produced by the EZNEC modeling program (left) and the AntennaSmith antenna analyzer (right). The 2:1 SWR line in the AntennaSmith plot is the red vertical line on the left size of the plot. The green area of the plot is the SWR for frequencies as measured during the sweep of the band. The shape of the measured plot differs from the shape of the predicted plot, but both plots show the antenna to have SWR


46

under 1.5:1 for the bulk of the band and the differences can be attributed to the effects of ground, the antenna coupling to nearby objects, or the effects of the coax run between the analyzer and the antenna. The far field plots over good ground give us some idea of the gain (dBi) and take-off angle of the antenna. These plots appear below.

Force-12 Sigma-5 on 10m Force-12 Sigma-5 on 10m

Figure 48 Force-12 Sigma-5 on 10m over good ground

Unfortunately, some of the more interesting places we might visit are sandy with very poor ground. The plots below illustrate those same plots over poor ground.


Figure 49 Force-12 Sigma-5 on 10m over poor ground


47

Two items from these plots give us an idea of what the poorer ground has done to our signal. The overall gain has gone down slightly and the take-off angle has gone up. Compare these results with the quarter-wave vertical and full-sized vertical dipole described earlier. The next few plots are over poor ground.

10m quarter wave Full-sized vertical dipole

Figure 50 EL 10m quarter wave and vertical dipole over poor ground

The gain for the full-sized vertical dipole is about 0.61 dBi. The gain for the Force-12 Sigma-5 over the same ground is -0.45 dBi. That is a difference of about 1 dB or a factor of 1.25. The difference between the quarter-wave vertical and the Force-12 Sigma-5 is less than half a dB.

The take-off angle for the full-sized vertical dipole remains low even over poor ground. The take-off angle for both the quarter-wave vertical and the Force-12 Sigma-5 is about 25 degrees (five degrees higher than the full-sized vertical dipole). So, the smaller Force-12 Sigma-5 compares favorably with the quarter-wave vertical and is only a few degrees higher than the full-sized vertical dipole on this band.

Returning to the criteria for lightweight DXpeditioning, we are seeking antennas that are light, easy to set up, easy to break down, and that have a small footprint and low visual profile. The Force-12 Sigma-5 is much easier to assemble and erect than either of the other two antennas and is much smaller. For 10 meters, the Force-12 Sigma-5 is a very good antenna for our purposes.

6.2 Force-12 Sigma-5 matching coil calculations

Each of the bands for the Force-12 Sigma-5 are matched by adding some inductive loading. (There is no inductive loading for 10-meters in the actual antenna but my model requires a little. This is evidence that the model does not precisely describe the product.) Measurements of the various loading coil diameters, number of turns, and coil lengths are


48

shown in the table below. The values for the calculated inductive loads are shown along with the actual inductive loads used in the model (which are slightly higher).

Measured in antenna Guess Determined by

modeling

Name Diameter Number of

turns

Length XL Total XL Actual XL

10m - - - - - 0.30

12m 1.0 4 1.3 0.22 0.22 0.65

15m 1.0 4 0.5 0.42 0.64 1.21

17m 1.0 5 0.65 0.58 1.22 1.92

20m 1.5 7 1.4 1.43 2.65 3.45 + 2 pF

Table 1 Force-12 Sigma-5 loading coil values

The values in the “Determined by modeling” column are used in subsequent calculations in the next sections.


The physical dimensions of the Force-12 Sigma-5 antenna do not change when changing bands. The next few sections will therefore concentrate on the performance of the antenna only and not review other aspects. Further, only the “loads” portion of the antenna model will be shown as all other elements of the model are identical to the 10-meter version (except starting frequency).

The loading discussed in the previous section was used to produce load elements as per the description below.

-------------- LOADS (RLC Type) --------------



1 2 47.00 47.73 11 Open 0.65 Open 24.9 Par

2 2 55.00 56.82 13 Open 0.65 Open 24.9 Par

3 2 50.00 52.27 12 Short 0.52 Short 0 Ser

These values give us the following SWR plot:


49



The plots for the 10-meter band selection on this antenna showed that the Force-12 Sigma-5 performed relatively well when compared to both a quarter-wave vertical with radials and a full-sized half-wave dipole. The plots for the 12-meter band selection show that moving to this new band did not sacrifice anything.


50



There was a small reduction in gain over poor ground but the take-off angle remained at 25 degrees as shown in the plots below.



The Force-12 Sigma-5 was a good antenna on 10m and remains a good antenna when switched to 12m compared to a quarter-wave radiator.


51


The match on 15 meters is under 2:1 for the entire band with the dip just before the center of the band. We must remember that these numbers are for the model of the antenna (but the model’s predictions have been verified by direct measurement).

-------------- LOADS (RLC Type) --------------



1 2 47.00 47.73 11 Open 1.21 Open 21.2 Par

2 2 55.00 56.82 13 Open 1.21 Open 21.2 Par

3 2 50.00 52.27 12 Short 0.52 Short 0 Ser



Though this antenna is relatively short for a 15 meter antenna the resistance presented is still relatively high. Assuming all this resistance is not losses, why would the radiation resistance be so high? Consider the surface area of a 16 AWG wire. The diameter of this wire is about 0.05 inches. The circumference is therefore just under 0.16 inches (0.05 * pi). The circumference of the one inch aluminum pipe is 3.14 inches. That is nearly 20 times the surface area of the wire! That is much more metal to radiate.


52

The far field plots show the gain even lower than that of the 12m antenna (-0.33 versus -0.04). But, the antenna has lost less than a half a dB from the 10m configuration (-33 versus +0.44). The take-off angle has remained steady at 25 degrees as shown in the plots below.



Moving the antenna over poor ground erodes the gain by nearly a dB (-0.33 versus -1.2) as shown in the plots below.




53


As we move down in frequency the dimensions of the antenna become smaller when compared to the size of a full-wave. The bottom two bands (17m & 20m) require significantly more loading that the others. The loading for 17 meters is shown below.

-------------- LOADS (RLC Type) --------------



1 2 47.00 47.73 11 Open 1.92 Open 18.1 Par

2 2 55.00 56.82 13 Open 1.92 Open 18.1 Par

3 2 50.00 52.27 12 Short 0.52 Short 0 Ser

This provides a nearly flat SWR curve over the whole 100 KHz of the band.



The far-field plot for the Sigma-5 over good ground on 17m appears below.


54



This is the same antenna configuration over poor ground. Again, the effect of a lossy ground in the near field degrades gain by nearly a dB.




Twenty meters is the lowest band for the Force-12 Sigma-5. The loading for this band is shown below.


55

-------------- LOADS (RLC Type) --------------



1 2 47.00 47.73 11 Open 3.45 2 14.1 Par

2 2 55.00 56.82 13 Open 3.45 2 14.1 Par

3 2 50.00 52.27 12 Short 0.52 Short 0 Ser

This loading provides a 2:1 match over about 200 KHz of the band. The manual for the antenna provides instructions on how to adjust the coil to change the center frequency of the antenna for this band. Spreading the coils slightly changes the inter-winding capacitance of the coil. In fact, it was necessary to add a small capacitance (2 pF) to the model to show this nice SWR plot.

Measurement not taken



The far-field plots for this antenna on 20m over good ground follows.


56



Below is a far-field plot for this antenna on 20m over poor ground.




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7 TW ANTENNAS TW2010 TRAVELER

The TW Antennas TW2010 Traveler antenna is similar in design to the Force-12 Sigma-5. The notable differences are in the height of the antenna (the Traveler is shorter), the length of the arms (the traveler has longer arms), the diameter of the elements (the Traveler uses one inch aluminum tubing for all elements), and the control mechanism (the Traveler has a electronics control package that can perform automatic band switching when connected to a radio).

Both antennas use loading coils and relays to select the combination of coils in use. Both antennas sit relatively low to the ground and depend on the large capacity hats to provide good efficiencies and matches on the five supported bands.

The TW Antennas TW2010 Traveler is a relatively new antenna as of this writing. The analysis below shows that it is competitive with the Force-12 Sigma-5 with performance down 0.7 to 1.5 dB from the Force-12 offering. The take-off angle of the Traveler also rises about 5 degrees from the Force-12. Still, the TW Antennas Traveler packs and travels better than the Force-12 Sigma-5, and deployment is easier than the Sigma-5 with no tools (and no bolts) assembly.

The next few sections will discuss the TW Antennas TW2010 Traveler antenna. As with the Force-12 Sigma-5, the various bands will be treated as different antennas though they all use the same physical structure. Band changes indicate a change in the loading coils; band changes do not require any other physical changes to the antenna.

7.1 TW Antennas TW2010 Traveler on 10 meters

The TW Antennas Traveler model is nearly identical to the Force-12 Sigma-5 with just a few things changed. Like the Force-12 Sigma-5, the TW Antennas Traveler has a matching stub (coil) to counteract the large capacitance from the arms. The details of this stub follows.

Name Diameter Number of turns Length XL

Stub 0.65 4 1 0.37 H

The methodology for determining this value is described in the next section. Here are the model details for the TW Traveler antenna including the loading information for 10 meters.

EZNEC+ ver. 5.0

TW Antennas Traveler 8/29/2007 3:54:19 PM




--------------- WIRES ---------------



1 W2E1 0, 0, 20 W4E1 0, 0, 100 1 30 1 0

2 W3E1 0, 0, 20 0, -30, 20 1 11 1 0


58

3 W1E1 0, 0, 20 0, 30, 20 1 11 1 0

4 W5E1 0, 0, 100 0, -30, 100 1 11 1 0

5 W1E2 0, 0, 100 0, 30, 100 1 11 1 0

Total Segments: 74

-------------- SOURCES --------------



1 1 50.00 51.67 16 1 0 I

-------------- LOADS (RLC Type) -------------



1 1 48.00 48.33 15 Open 0.28 0 28.3 Par

2 1 54.00 55.00 17 Open 0.28 0 28.3 Par

3 1 50.00 51.67 16 Short 0.37 Short 0 Ser





--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.005 13 0 0

This model provides the following view of the antenna.

Figure 63 TW Antennas Traveler model view

As with the Force-12 Sigma-5, we shall present the 10 meter data here and then show only the different loading for the other bands serviced by this antenna.


59

The stub and loading coil values provide the following SWR on the 10-meter band.

Figure 64 SWR for TW Antennas Traveler on 10m

The far field plots for this antenna on 10-meters over good ground appears below

TW Antennas Traveler on 10m TW Antennas Traveler on 10m

Figure 65 TW Antennas Traveler on 10m over good ground

The far-field plot for this antenna on 10m over poor ground appears below.


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Figure 66 TW Antennas Traveler on 10m over poor ground

Comparisons to the performance of the Force-12 Sigma-5 can now be made. Below are a sequence of figures with the Sigma-5 plot on the left and Traveler on the right.

Force-12 Sigma-5 TW Antennas Traveler

Figure 67 AZ Sigma-5 and Traveler on 10m over good ground


61


Figure 68 EL Sigma-5 and Traveler on 10m over good ground


Figure 69 AZ Sigma-5 and Traveler on 10m over poor ground


62


Figure 70 EL Sigma-5 and Traveler on 10m over poor ground

7.2 TW Antennas TW2010 Traveler matching coil calculations

Measuring the coils is straightforward if you have the hardware in front of you. But, how do you measure things if you don’t? What if you don’t own the device? As I did not own this antenna when the analysis was first done, this was the first problem to overcome. (I have since purchased the antenna.) The solution was to measure from a photograph instead of from the coils themselves. Adobe Photoshop provides all the tools you need. The techniques shown here should be useful for any challenge of this type. Here is how I did it.

I took a photograph of the match-box that was featured in the TW Antennas brochure. This was a PDF so much of the detail remained when the page was enlarged. Once I had a view with sufficient detail, I captured that portion of the brochure into a file and opened Photoshop.

Once the image was opened with Photoshop it was just a matter of scaling the picture so the aluminum pipe was measured to be one inch in the Photoshop ruler system. All other distances could be approximated using the Photoshop measuring tool. A figure below illustrates this.


63

Figure 71 Measuring Traveler coils with Photoshop

The measurements and final inductances after experimental modeling appear below. As you can see, these values were about as close as those measured directly on the Force-12 Sigma-5. And, all this was from just a picture!

Measured in antenna Guess Determined by modeling

Name Diameter Number of turns

Length XL Total XL Actual XL

10m 0.85 2 0.2 0.12 0.12 0.28

12m 0.65 3 0.3 0.16 0.28 0.58

15m 0.75 4 0.3 0.35 0.64 1.10

17m 0.75 5 0.52 0.41 1.05 1.75

20m 0.7 8 0.83 0.68 1.73 3.25 + 1 pF

Table 2 TW Antenna Traveler coil values


64

7.3 TW Antennas Traveler on 12 meters

The model data for the TW Antennas Traveler antenna on 12 meters is the same as the 10-meter model except for the loading. Those details are found below.

-------------- LOADS (RLC Type) -------------



1 1 48.00 48.33 15 Open 0.58 0 24.9 Par

2 1 54.00 55.00 17 Open 0.58 0 24.9 Par

3 1 50.00 51.67 16 Short 0.37 Short 0 Ser


The far-field plots for this antenna on 12m over good ground appear below.


65



The far-field plots for this antenna on 12m over poor ground appear below.



Again, we compare the two very similar antenna designs of the Force-12 Sigma-5 and the TW Antennas TW2010 with side-by-side far-field plots over good ground and poor ground.


66






67






68



-------------- LOADS (RLC Type) -------------



1 1 48.00 48.33 15 Open 1.1 0 21.2 Par

2 1 54.00 55.00 17 Open 1.1 0 21.2 Par

3 1 50.00 51.67 16 Short 0.37 Short 0 Ser


The far-field plots for this antenna on 15m over good ground appears below.


69

TW Antennas Traveler TW Antennas Traveler

Figure 80 TW Antennas Traveler over good ground




Direct comparisons using far-field plots for the Sigma-5 and TW2010 are shown below.


70






71







-------------- LOADS (RLC Type) -------------


72



1 1 48.00 48.33 15 Open 1.75 0 18.1 Par

2 1 54.00 55.00 17 Open 1.75 0 18.1 Par

3 1 50.00 51.67 16 Short 0.37 Short 0 Ser


The far-field plots for this antenna on 17m over good ground appears below.


73






Comparisons between the Sigma-5 and TW2010 are shown with far-field plots over both good and poor ground below.


74






75







-------------- LOADS (RLC Type) --------------


76

No. Specified Pos. Actual Pos. R L C Freq Type


1 1 48.00 48.33 15 Open 3.25 1 14.2 Par

2 1 54.00 55.00 17 Open 3.25 1 14.2 Par

3 1 50.00 51.67 16 Short 0.37 Short 0 Ser


The far field plot for this antenna on 20m over good ground appears below.


77







78

Comparisons of the Sigma-5 and TW2010 on 20m over both good and poor ground are made with far-field plots below.






79






80

8 STANDARD BUDDIPOLE

The Buddipole Antennas Buddipole (just “Buddipole” henceforth) is really an antenna component system that allows for the construction and deployment of many different antenna configurations depending on the requirements. The standard package can be used to build antennas covering 2-40 meters. Larger coils are available that provide for the construction of 80 meter antennas. There is no Buddipole antenna to evaluate; there are many, many Buddipole configurations to evaluate. This white paper will attempt to evaluate some small subset of these options.

There are several components that are used to construct these antenna configurations. Some of these are:

• 22 inch antenna arm – This is an aluminum tube 0.75 inches in diameter and 21.5 inches in length (plus threading on one end).

• Black coil – The Buddipole system comes with two coils: a Black coil and a Red coil. Dimensions and corresponding inductances for popular tap-points are given in a table below.

• Red coil – Similar to the Black coil.

• 5.5 foot whips – There are several styles of whips available in differing lengths, colors, and construction. The standard Buddipole package uses stainless steel 5.5 foot whips.

• VersaTee – This is the feed point for the antenna and the place where elements are affixed. There is a threaded hole in the bottom of this block to accept the standard Buddipole mast. Three threaded mounts appear on the left, right, and top of the VersaTee to accept antenna arms or whips.

There are many other accessories but the first models will consist of only these items. One of the important things about this system is that it packs small and travels well. The long bag holds the system and the 16 foot mast; the small bag holds the system and the 8 foot mast. Pictures of the packed systems appear below.


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Long Buddipole in bag Small Buddipole system in the bag

Figure 100Buddipole in the bag

The two coils Black and Red are 1.5 inches in diameter and have 12 turns per inch. Default settings call for specific taps and whip lengths. Those taps are shown below along with the associated inductance.

BLACK

Tap Diameter length X(L)

2 1.5 0.17 0.27

4 1.5 0.33 0.89

6 1.5 0.50 1.72 Black

14 1.5 1.17 5.99 Blue

19 1.5 1.58 8.99

36 1.5 3.00 19.84 No

RED

Tap Diameter length X(L)

2 1.5 0.17 0.27

4 1.5 0.33 0.89 Red

10 1.5 0.83 3.73 Green

23 1.5 1.92 11.48 Blue

40 1.5 3.33 22.45 No

Construction of the basic dipole configuration can be achieved by following a simple recipe of assembling the antenna and selecting the appropriate coil taps and whip lengths. After assembly, fine tuning can be done by adding or subtracting a little whip length from one side or the other.

The act of “tapping” a coil is done by inserting a small hook into the coil windings. There is a threaded head on the top of this hook and a plastic knob screwed into the thread. To tap a coil just loosen the plastic knob on the top of the hook, thread the hook


82

through the appropriate coil winding, and then tighten the knob until the hook is snug against the wire. A five-inch wander lead is attached to each coil. This wander lead is inserted into the top of the hook to complete the connection. Tapping a coil typically takes only a few seconds.

Note that the five-inch wander lead must be included in the length of one of the wires for our model. I have added those five inches to the length of the whips so each specified whip length is augmented by five inches for each design.

The recommended recipes for Buddipole dipole configurations appears below.

BASIC DIPOLE TUNING

RED SIDE BLACK SIDE

BANDS Coils Total whip

sections out

Tap Coils Total whip

sections out

Tap

40 meters YES 5.5 NO YES 5 NO

30 meters YES 6 23 YES 6 19

20 meters YES 6 GREEN 10 YES 6 BLUE 14

17 meters YES 4.5 GREEN 10 YES 6 BLACK 6

15 meters YES 6 RED 4 YES 6 BLACK 6



6 meters Whips only (no coils, no arms) – 4.5 sections out each side

2 meters Whips only (no coils, no arms) 1 section + 2 inches (15” total) each side

Table 3 Recipes for Buddipole dipole configurations

These recipes are good starting points for tuning the Buddipole but the effects of ground, proximity of nearby objects, or even particular band segment to be match will demand variants. The two most obvious variations are obtained by either lengthening or shortening a whip or by tapping a different coil turn.

As of this writing the Buddipole “Deluxe Package” configuration was $399 and consisted of the following:

• The Buddipole Antenna (9 bands, 2 - 40 meters) with 25 foot coax assembly (includes VersaTee)

• Tripod - extendable legs and locking base

• Portable Mast – extends to 8’ in height


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• Rotating Arm Kit – change configurations

• Antenna System Bag – padded Cordura nylon w/shoulder strap

• Extra Stainless Steel Telescopic Whip

• 3 Coil Clips

• Antenna Operating Manual

• A 10-page modeling report

Substituting a 16 foot mast and longer bag brings the total system cost to $454 (as of this writing). One additional part will also be included in the analysis. The Triple Ratio Switched Balun (TRSB) is a device that can be placed at the feed point that provides good isolation of the feed line from the antenna and a switched transformer that can match 50:50 ohms (1:1), 50:25 ohms (2:1), or 50:12.5 ohms (4:1) to accommodate antenna configurations with very low impedances. The TRSB is $79 bringing the total of the evaluated system to $533.

This white paper will consider the following configurations that can be constructed with the standard Buddipole kit (plus extra parts as described above).

• Dipole

• An “L” with a vertical “hot side” and horizontal “cold side”

• A vertical with sloping radial

The configurations will appear at differing mast heights to show the affect of mast height on performance. We begin with the humble dipole.

8.1 Buddipole Horizontal Dipole

The standard Buddipole masts are either 8 feet or 16 feet in length. A dipole at 16 feet for any band but 10 meters is a very, very low dipole. Modeling confirms that a low-hung horizontal dipole does not yield good results for DX work.

8.1.1 Buddipole Horizontal Dipole for 10-meters at 8 feet

This is one of the most simple configurations for the Buddipole. The VersaTee has two horizontal elements. One side has (starting from the center) one 22-inch arm, the Black coil, and one six foot whip. The other side has one 22-inch arm, the Red coil, and one six foot whip. Both coils are tapped at the second turn.

Here is the model file for this antenna:

EZNEC+ ver. 5.0

Buddipole dipole 10m @ 8 ft 8/29/2007 10:38:43 PM



Wire Loss: Aluminum (6061-T6) – Resistivity = 4E-08 ohm-m, Rel. Perm. = 1

--------------- WIRES ---------------




84

1 W2E2 0, -22, 96 W3E1 0, 22, 96 0.75 11 1 0

2 0, -93, 96 W1E1 0, -22, 96 0.5 11 1 0

3 W1E2 0, 22, 96 0, 82.5, 96 0.5 11 1 0

Total Segments: 33

-------------- SOURCES --------------



1 1 50.00 50.00 6 1 0 I

-------------- LOADS (RLC Type) --------------



1 1 0.00 4.55 1 Short 0.27 Short 28.3 Ser

2 1 100.00 95.45 11 Short 0.27 Short 28.3 Ser





--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.001 5 0 0

This model gives us the following antenna view in EZNEC:

Figure 101 Buddipole on 10m at 8 feet

This is a very low dipole even for 10 meters. The far field plots confirm that the take-off angle for this antenna is very high. The plot for this antenna on 10m over good ground appears below.


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Buddipole 10m horizontal dipole at 8 feet Buddipole 10m horizontal dipole at 8 feet

Figure 102 Buddipole horizontal dipole for 10m at 8 feet over good ground

The far-field plot for the antenna over poor ground appears below.


Figure 103 Buddipole horizontal dipole for 10m at 8 feet over poor ground


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No other HF dipole configurations will be modeled for the 8-foot mast as the pattern can only get worse for bands below 10 meters. Instead, all subsequent dipole analysis will be done on the 16-foot mast.


The Buddipole system has two standard mast lengths: 8 foot and 16 foot. Below is an alalysis for the 10-meter configuration raised to 16 feet. The SWR plot did not change much and the bulk of the 10 meter band is better than 2:1. The only thing that changed in these two models is the Z component of the three wires. Here is the model for this antenna.

EZNEC+ ver. 5.0

Buddipole dipole 10m @ 8 ft 8/29/2007 10:38:43 PM




--------------- WIRES ---------------



1 W2E2 0, -22, 192 W3E1 0, 22, 192 0.75 11 1 0

2 0, -93, 192 W1E1 0, -22, 192 0.5 11 1 0

3 W1E2 0, 22, 192 0, 82.5, 192 0.5 11 1 0

Total Segments: 33

-------------- SOURCES --------------



1 1 50.00 50.00 6 1 0 I

-------------- LOADS (RLC Type) --------------



1 1 0.00 4.55 1 Short 0.27 Short 28.3 Ser

2 1 100.00 95.45 11 Short 0.27 Short 28.3 Ser





--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.001 5 0 0

The SWR plot for this antenna appears below.


87


Figure 104 SWR for Buddipole horizontal dipole for 10m at 16 feet

The far-field plot for the Buddipole dipole configuration for 10-meters over good ground at 16 feet appears below.


88






This antenna is worthy of comparison to some of the vertical antennas described earlier. One of the better antennas was the full-sized vertical dipole for 10-meters. We compare that antenna to this new Buddipole configuration over good ground.


89

Half-wave vertical dipole on 10m Buddipole 10m horizontal dipole at 16 feet

Figure 107 Half-wave vertical dipole vs. Buddipole horizontal dipole for 10 meters

The clear winner here is the Buddipole dipole configuration with nearly 7 dBi of gain versus the vertical at less than 1 dBi. Assuming the target is broadside to the antenna, you get about an S-unit improvement over the vertical. Even with the take-off angle of the vertical being ten degrees lower than the Buddipole horizontal dipole, the Buddipole wins.


The Buddipole dipole on 12m at a height of 16 feet appears below. Here is the model for this antenna.

EZNEC+ ver. 5.0

Buddipole dipole 12m @16 ft 8/30/2007 8:18:05 AM




--------------- WIRES ---------------



1 W2E2 0, -22, 192 W3E1 0, 22, 192 0.75 11 1 0

2 0, -93, 192 W1E1 0, -22, 192 0.5 11 1 0

3 W1E2 0, 22, 192 0, 93, 192 0.5 11 1 0

Total Segments: 33

-------------- SOURCES --------------



90


1 1 50.00 50.00 6 1 0 I

-------------- LOADS (RLC Type) --------------



1 1 0.00 4.55 1 Short 0.89 Short 24.9 Ser

2 1 100.00 95.45 11 Short 0.27 Short 24.9 Ser





--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.005 13 0 0

The SWR plot for the Buddipole dipole for 12-meters at 16 feet appears below.



The far-field plot for the Buddipole dipole for 12-meters at 16 feet over good ground appears below.


91



The Buddipole dipole for 12-meters at 16 feet over poor ground appears below.




92


The Buddipole on 15 meters at 16 feet appears below. Here is the model for this antenna.

EZNEC+ ver. 5.0





--------------- WIRES ---------------


Insulation


1 W2E2 0, -22, 192 W3E1 0, 22, 192 0.75 11 1 0

2 0, -93, 192 W1E1 0, -22, 192 0.5 11 1 0

3 W1E2 0, 22, 192 0, 93, 192 0.5 11 1 0

Total Segments: 33

-------------- SOURCES --------------



1 1 50.00 50.00 6 1 0 I

-------------- LOADS (RLC Type) --------------



1 1 0.00 4.55 1 Short 1.72 Short 21.2 Ser

2 1 100.00 95.45 11 Short 0.89 Short 21.2 Ser





--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.005 13 0 0

The SWR plot for the Buddipole dipole on 15-meters at 16 feet appears below.


93



The predicted SWR curve looks much different than that measured by the AntennaSmith. This could easily be due to the effects of the particular ground or proximity of other objects in the near field of the antenna. Again, as with the 10-meter antenna at only 8 feet, this 15-meter antenna at only 16 feet is very, very low for a dipole as evidenced by the far-field plots below. The far-field plot for the Buddipole on 15-meters at 16 feet over good ground appears first.


94



The Buddipole dipole for 15-meters at 16 feet over poor ground appears below.




95


The Buddipole on 17-meters at 16 feet appears below. Here is the model data for this antenna.

EZNEC+ ver. 5.0





--------------- WIRES ---------------


Conn. X Y Z Conn. X Y Z Diel CThk(in)

1 W2E2 0, -22, 192 W3E1 0, 22, 192 0.75 11 1 0

2 0, -93, 192 W1E1 0, -22, 192 0.5 11 1 0

3 W1E2 0, 22, 192 0, 73, 192 0.5 11 1 0

Total Segments: 33

-------------- SOURCES --------------



1 1 50.00 50.00 6 1 0 I

-------------- LOADS (RLC Type) --------------



1 1 0.00 4.55 1 Open 1.72 1 18.1 Par

2 1 100.00 95.45 11 Open 3.73 1 18.1 Par





--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.005 13 0 0

The dipole has an extremely low resistance. The Buddipole Triple Ratio Switched Balun (TRSB) provides a switched transformer that matches a 50 ohm feed line to a 25 ohm load, or a 12.5 ohm load. This configuration presents 25 ohms so the 2:1 setting of the TRSB will be employed. This yields the SWR graph as shown below.


96




The tuning is very sharp for this antenna. This configuration is impractical for DX operation with its tedious tuning and high take-off angle.

Note that as sharp as the tuning might be for the 17-meter dipole configuration, it would be even worse for the 20-meter dipole configuration. Further, the 20-meter antenna at 16 feet would be at least as bad as the 10-meter antenna at 8 feet. Therefore, the 20-meter antenna will not be evaluated here.

For illustrate these problems the far-field plot for the 17-meter dipole configuration at 16-feet over good ground is presented above. Note the extremely high take-off angle.


97



The Buddipole dipole configuration for 17-meters at 16 feet over poor ground is shown below.




98

8.2 Buddipole Vertical with L-arm radial at 8 feet

The “L” antenna is like the dipole except that the “hot” side of the antenna is mounted on the top of the VersaTee to make a vertical antenna with one (loaded) radial. I have used this configuration occasionally but the long and heavy horizontal piece make the antenna precarious to balance since the center of gravity is so far away from the mast. Also, as can be seen by the plots below, the pattern from the antenna is a bit bizarre. Perhaps this section is an exercise in what not to do.

8.2.1 Buddipole Vertical with L-arm radial for 10m at 8 feet

The “L” for 10 meters at 8 feet appears below. Here is the model data for that antenna.

EZNEC+ ver. 5.0

Buddipole vert-L 10m at 8 ft 8/30/2007 11:30:32 AM




--------------- WIRES --------------



1 W3E1 0, 0, 192 W2E1 0, 0, 214 0.75 11 1 0

2 W1E2 0, 0, 214 0, 0, 280 0.5 11 1 0

3 W1E1 0, 0, 192 W4E1 0, 22, 192 0.5 11 1 0

4 W3E2 0, 22, 192 0, 93, 192 0.5 11 1 0

Total Segments: 44

-------------- SOURCES --------------



1 1 0.00 4.55 1 1 0 I

-------------- LOADS (RLC Type) --------------



1 1 100.00 95.45 11 Open 0.27 Open 28.3 Par

2 3 100.00 95.45 11 Open 0.27 Open 28.3 Par





--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.005 13 0 0


99

The TRSB is used to match the antenna at 25 ohms which yields the following SWR curve. Note that if you wished to match the CW portion of the 10 meter band that the top whip can be pulled out a few more inches to shift the center frequency down.



Figure 117 SWR for Buddipole vertical with L-radial on 10m at 8 feet

This antenna is illustrated below.


100

Figure 118 Buddipole vertical with L-radial on 10m at 8 feet

The far-field pattern for this antenna over good ground appears below.

Buddipole vertical with L-radial on 10m Buddipole vertical with L-radial on 10m

Figure 119 Buddipole vertical with L-radial on 10m at 8 feet over good ground

The far-field pattern for this antenna over poor ground appears below.


101


Figure 120 Buddipole vertical with L-radial on 10m at 8 feet over poor ground


The “L” for 12 meters appears below.


Here is the model data for this antenna.

EZNEC+ ver. 5.0

Buddipole vert-L 12m at 8 ft 8/30/2007 11:51:05 AM





102

--------------- WIRES ---------------



1 W3E1 0, 0, 192 W2E1 0, 0, 214 0.75 11 1 0

2 W1E2 0, 0, 214 0, 0, 285 0.5 11 1 0

3 W1E1 0, 0, 192 W4E1 0, 22, 192 0.5 11 1 0

4 W3E2 0, 22, 192 0, 93, 192 0.5 11 1 0

Total Segments: 44

-------------- SOURCES --------------



1 1 0.00 4.55 1 1 0 I

-------------- LOADS (RLC Type) --------------



1 1 100.00 95.45 11 Open 0.89 Open 24.9 Par

2 3 100.00 95.45 11 Open 0.27 Open 24.9 Par





--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.005 13 0 0


103







104







EZNEC+ ver. 5.0


105

Buddipole vert-L 15m at 8 ft 8/30/2007 1:06:51 PM




--------------- WIRES ---------------



1 W3E1 0, 0, 192 W2E1 0, 0, 214 0.75 11 1 0

2 W1E2 0, 0, 214 0, 0, 280 0.5 11 1 0

3 W1E1 0, 0, 192 W4E1 0, 22, 192 0.5 11 1 0

4 W3E2 0, 22, 192 0, 93, 192 0.5 11 1 0

Total Segments: 44

-------------- SOURCES --------------



1 1 0.00 4.55 1 1 0 I

-------------- LOADS (RLC Type) --------------



1 1 100.00 95.45 11 Open 1.72 Open 21.2 Par

2 3 100.00 95.45 11 Open 0.89 Open 21.2 Par





--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.005 13 0 0



106






107







108




Here is the model data for this antenna

EZNEC+ ver. 5.0





--------------- WIRES ---------------



1 W3E1 0, 0, 192 W2E1 0, 0, 214 0.75 11 1 0

2 W1E2 0, 0, 214 0, 0, 260 0.5 11 1 0

3 W1E1 0, 0, 192 W4E1 0, 22, 192 0.5 11 1 0

4 W3E2 0, 22, 192 0, 93, 185 0.5 11 1 0

Total Segments: 44

-------------- SOURCES --------------



1 1 0.00 4.55 1 1 0 I

-------------- LOADS (RLC Type) --------------



1 1 100.00 95.45 11 Open 1.72 Open 18.1 Par


109

2 3 100.00 95.45 11 Open 3.73 Open 18.1 Par





--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.005 13 0 0







110







111





EZNEC+ ver. 5.0





--------------- WIRES ---------------



1 W3E1 0, 0, 192 W2E1 0, 0, 214 0.75 11 1 0

2 W1E2 0, 0, 214 0, 0, 267 0.5 11 1 0

3 W1E1 0, 0, 192 W4E1 0, 22, 192 0.5 11 1 0

4 W3E2 0, 22, 192 0, 89, 192 0.5 11 1 0

Total Segments: 44

-------------- SOURCES --------------



1 1 0.00 4.55 1 1 0 I

-------------- LOADS (RLC Type) --------------



1 1 100.00 95.45 11 Open 5.99 Open 14.1 Par

2 3 100.00 95.45 11 Open 3.73 Open 14.1 Par






112

--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.005 13 0 0





Note that the matching for this antenna required an 8:1 transformer matching 50 ohms to 6.25 ohms just to get a 2:1 SWR over 50 KHz. Tuning is very sharp on this antenna because the radiation resistance is very low and capacitive and inductive reactance values can vary greatly compared to that low ohmic resistance. This is basically an unusable configuration at 8 feet.



113







114

8.3 Buddipole Vertical with L-arm radial at 16 feet

The antenna systems described above are now brought up to 16 feet. The models below are simply translated up to this new height. The higher feed point and element heights make a big difference as evidenced by the plots below.

This system has the same problems as the “L” at 8 feet. The center of gravity of the antenna is far from the mast, the patterns are bizarre, and it still doesn’t match well on 20 meters. The problem common with all these antennas is they are very short for these lower bands. The 6 foot stainless steel whips are simply too short to provide a good radiator for 15 meters and below. This is discussed more extensively in the Long Buddipole section.

In the mean time, the “L” configuration at 16 feet is explored below.





EZNEC+ ver. 5.0





--------------- WIRES ---------------



1 W3E1 0, 0, 288 W2E1 0, 0, 310 0.75 11 1 0

2 W1E2 0, 0, 310 0, 0, 376 0.5 11 1 0

3 W1E1 0, 0, 288 W4E1 0, 22, 288 0.5 11 1 0

4 W3E2 0, 22, 288 0, 93, 288 0.5 11 1 0


115

Total Segments: 44

-------------- SOURCES --------------



1 1 0.00 4.55 1 1 0 I

-------------- LOADS (RLC Type) --------------



1 1 100.00 95.45 11 Open 0.27 Open 28.3 Par

2 3 100.00 95.45 11 Open 0.27 Open 28.3 Par





--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.005 13 0 0






116







117





EZNEC+ ver. 5.0




Wire Loss: Aluminum (6061-T6) -- Resistivity = 4E-08 ohm-m, Rel. Perm. =

--------------- WIRES ---------------



1 W3E1 0, 0, 288 W2E1 0, 0, 310 0.75 11 1 0

2 W1E2 0, 0, 310 0, 0, 381 0.5 11 1 0

3 W1E1 0, 0, 288 W4E1 0, 22, 288 0.5 11 1 0

4 W3E2 0, 22, 288 0, 93, 288 0.5 11 1 0

Total Segments: 44

-------------- SOURCES --------------



1 1 0.00 4.55 1 1 0 I

-------------- LOADS (RLC Type) --------------



1 1 100.00 95.45 11 Open 0.89 Open 24.9 Par

2 3 100.00 95.45 11 Open 0.27 Open 24.9 Par





118


--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.005 13 0 0






119







120





EZNEC+ ver. 5.0





--------------- WIRES ---------------



1 W3E1 0, 0, 288 W2E1 0, 0, 310 0.75 11 1 0

2 W1E2 0, 0, 310 0, 0, 377 0.5 11 1 0

3 W1E1 0, 0, 288 W4E1 0, 22, 288 0.5 11 1 0

4 W3E2 0, 22, 288 0, 93, 288 0.5 11 1 0

Total Segments: 44

-------------- SOURCES --------------



1 1 0.00 4.55 1 1 0 I

-------------- LOADS (RLC Type) -------------



1 1 100.00 95.45 11 Open 1.72 Open 21.2 Par

2 3 100.00 95.45 11 Open 0.89 Open 21.2 Par





121


--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.005 13 0 0






122







123





EZNEC+ ver. 5.0





--------------- WIRES --------------



1 W3E1 0, 0, 288 W2E1 0, 0, 310 0.75 11 1 0

2 W1E2 0, 0, 310 0, 0, 358 0.5 11 1 0

3 W1E1 0, 0, 288 W4E1 0, 22, 288 0.5 11 1 0

4 W3E2 0, 22, 288 0, 91.5, 288 0.5 11 1 0

Total Segments: 44

-------------- SOURCES --------------



1 1 0.00 4.55 1 1 0 I

-------------- LOADS (RLC Type) --------------



1 1 100.00 95.45 11 Open 1.72 Open 18.1 Par

2 3 100.00 95.45 11 Open 3.73 Open 18.1 Par






124

--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.005 13 0 0






125







126





EZNEC+ ver. 5.0





--------------- WIRES ---------------



1 W3E1 0, 0, 288 W2E1 0, 0, 310 0.75 11 1 0

2 W1E2 0, 0, 310 0, 0, 364 0.5 11 1 0

3 W1E1 0, 0, 288 W4E1 0, 22, 288 0.5 11 1 0

4 W3E2 0, 22, 288 0, 90, 288 0.5 11 1 0

Total Segments: 44

-------------- SOURCES --------------



1 1 0.00 4.55 1 1 0 I

-------------- LOADS (RLC Type) --------------

No. Specified Pos. Actual Pos. R L C R Freq

Type


1 1 100.00 95.45 11 Open 5.99 Open 14.1 Par

2 3 100.00 95.45 11 Open 3.73 Open 14.1 Par



127




--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.005 13 0 0





Again, even at 16 feet this is a very difficult antenna to match to 50 ohms. Though the height may be satisfactory for an antenna design like this, the element lengths are simply too short for this band. A similarly designed antenna with longer whips is discussed later and the longer element lengths make a big difference.



128







129

8.4 Buddipole vertical with single sloping radial at 16 feet

The previous Buddipole antennas were modeled without the effects of the mast. With this set of models we now begin to route portions of the antenna in the proximity of the mast so we can no longer ignore this big piece of metal. In fact, experiments using the modeling software show that the mast can have a significant affect on the characteristics and performance of the system it supports. Beginning with these sets of models a one inch mast will be included in the calculations that is specified to come just short of feed point and a few inches off the ground (to ensure we do not overstate the effects on either aspect). This mast definition is larger in diameter than the standard Buddipole mast systems but a little smaller than “painters poles” that are sometimes used for masts.

We are still using the short stainless steel whips for these antenna designs. The “wires” run down at a 45 degree angle can be either arms and whips (using the Rotating Arm Kit), or be actual wires. The larger diameter conductors are modeled. In the plots below.

8.4.1 Buddipole vertical with 1 radial for 10m at 16 feet

The vertical for 10 meters appears below. Here is the model data for this antenna.

Figure 157 Buddipole vertical for 10m with 1 radial

EZNEC+ ver. 5.0

BP vert 1 rad 10m at 16 ft 9/1/2007 12:09:16 AM




--------------- WIRES ---------------



1 W3E1 0, 0, 192 W2E1 0, 0, 214 0.75 11 1 0

2 W1E2 0, 0, 214 0, 0, 280 0.5 11 1 0

3 W1E1 0, 0, 192 0, 69, 123 0.5 11 1 0


130

4 0, 0, 6 0, 0, 186 1 11 1 0

Total Segments: 44

-------------- SOURCES --------------



1 1 0.00 4.55 1 1 0

-------------- LOADS (RLC Type) --------------



1 1 100.00 95.45 11 Open 0.27 Open 28.3 Par





--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.005 13 0 0



Figure 158 SWR for Buddipole vertical with 1 radial on 10m at 16 feet



131

Buddipole Vertical on 10m with 1 radial Buddipole Vertical on 10m with 1 radial

Figure 159 Buddipole vertical with 1 radial on 10m at 16 feet over good ground



Figure 160 Buddipole vertical with 1 radial on 10m at 16 feet over poor ground


132


The vertical for 12 meters appears below.



EZNEC+ ver. 5.0

BP vert 1 rad 12m at 16 ft 9/1/2007 12:44:44 AM




--------------- WIRES ---------------



1 W3E1 0, 0, 192 W2E1 0, 0, 214 0.75 11 1 0

2 W1E2 0, 0, 214 0, 0, 277 0.5 11 1 0

3 W1E1 0, 0, 192 0, 78, 114 0.5 11 1 0

4 0, 0, 6 0, 0, 186 1 11 1 0

Total Segments: 44

-------------- SOURCES --------------



1 1 0.00 4.55 1 1 0 I

-------------- LOADS (RLC Type) --------------



1 1 100.00 95.45 11 Open 0.89 Open 28.3 Par





133


--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.005 13 0 0






134







135




Below is the model data for this antenna.

EZNEC+ ver. 5.0

BP vert 1 rad 15m at 16 ft 9/2/2007 12:08:05 PM




--------------- WIRES ---------------



1 W3E1 0, 0, 192 W2E1 0, 0, 214 0.75 11 1 0

2 W1E2 0, 0, 214 0, 0, 273 0.5 11 1 0

3 W1E1 0, 0, 192 0, 94, 98 0.5 11 1 0

4 0, 0, 6 0, 0, 186 1 11 1 0

Total Segments: 44

-------------- SOURCES --------------



1 1 0.00 4.55 1 1 0 I

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The model data for this antenna appears below.

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1 W3E1 0, 0, 192 W2E1 0, 0, 214 0.75 11 1 0

2 W1E2 0, 0, 214 0, 0, 286 0.5 11 1 0

3 W1E1 0, 0, 192 0, 112, 76 0.5 11 1 0

4 0, 0, 6 0, 0, 186 1 11 1 0

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2 W1E2 0, 0, 214 0, 0, 262 0.5 11 1 0

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4 0, 0, 6 0, 0, 186 1 11 1 0

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9 LONG BUDDIPOLE

The Standard Buddipole system used just the compliment of parts included in the Buddipole Deluxe Package (plus TRSB). This chapter discusses options for antenna designs when extra components or substitute components are used.

9.1 Differences between the Standard Buddipole and Long Buddipole

One of the biggest problems with the antennas constructed from the Standard Buddipole system is the length of the whips. The 5.5 foot stainless steel whips are just too short to make good antennas on the lower bands. Buddipole offers longer whips into two forms:

• Shock-cord whips – These whips are constructed from solid aluminum pieces that are held together by a stretchy nylon rope in the middle. Similar to tent poles, these whips can be pulled apart for storage, or strung together to make a virtually unbreakable radiator. The advantages of these whips is their sturdiness; the disadvantage is they cannot be adjusted as finely as a regular whip. Costs range from $36 to $60 depending on length.

• Long telescopic whips – These whips extend to 9 feet 4 inches in length, nearly double the standard stainless steel whip. They collapse to about 22 inches so they can be stored and packed with other Buddipole parts. They are surprisingly resilient for their length. A long telescopic whip is $18 as of this writing.

The lengths of elements can also be increased by adding extra antenna arms. Each 22 inch aluminum piece not only adds length to an element but also adds bandwidth as the pieces are 0.75 inches in diameter (instead of the much smaller diameter whip sections).

The designs below will use the long telescopic whips instead of the shorter stainless steel whips. Designs will also incorporated 0, 1, or 2 arms as necessary to eliminate the need for loading coils. No coils are used in the following antenna system designs!

Each antenna has one radial running down from the feed point at an angle of 45 degrees (or less). In practice, the antenna is constructed so that the vertical radiator is full-sized based on the formula 234/f and the length of the radial is adjusted to bring the antenna into a good match for 50 ohms.

9.2 Buddipole full-sized vertical with 1 radial 8 feet

9.2.1 Buddipole full-sized vertical with 1 radial for 10m at 8 feet

The vertical for 10 meters appears below. We assume a whip can be used as the radial so it has a large diameter. Here is the model data for this antenna.


145

Figure 177 Buddipole full-sized vertical for 10m with 1 radial


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1 W3E1 0, 0, 96 W2E1 0, 0, 118 0.75 11 1 0

2 W1E2 0, 0, 118 0, 0, 198 0.5 11 1 0

3 W1E1 0, 0, 96 0, 69, 23 0.5 11 1 0

4 0, 0, 6 0, 0, 90 1 11 1 0

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Figure 178 SWR for BP full-sized vertical with 1 radial on 10m at 8 feet



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BP full-sized vertical on 10m with 1 radial BP Full-sized vertical on 10m with 1 radial

Figure 179 BP full-sized vertical with 1 radial on 10m at 8 feet over good ground


BP Full-sized vertical on 10m with 1 radial BP Full-sized vertical on 10m with 1 radial

Figure 180 Buddipole full-sized vertical, 1 radial on 10m at 8 feet over poor ground


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Conn. X Y Z Conn. X Y Z Diel

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1 W3E1 0, 0, 96 W2E1 0, 0, 118 0.75 11 1 0

2 W1E2 0, 0, 118 0, 0, 209 0.5 11 1 0

3 W1E1 0, 0, 96 0, 81, 14 0.5 11 1 0

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1 W3E1 0, 0, 96 W2E1 0, 0, 118 0.75 11 1 0

2 W1E2 0, 0, 118 0, 0, 230 0.5 11 1 0

3 W1E1 0, 0, 96 0, 129, 36 0.5 11 1 0

4 0, 0, 6 0, 0, 90 1 11 1 0

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1 W3E1 0, 0, 96 W2E1 0, 0, 139 0.75 11 1 0

2 W1E2 0, 0, 139 0, 0, 251 0.5 11 1 0

3 W1E1 0, 0, 96 0, 152, 36 0.5 11 1 0

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1 W3E1 0, 0, 96 W2E1 0, 0, 182 0.75 11 1 0

2 W1E2 0, 0, 182 0, 0, 294 0.5 11 1 0

3 W1E1 0, 0, 96 0, 198, 36 0.5 11 1 0

4 0, 0, 6 0, 0, 90 1 11 1 0

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9.3 Buddipole full-sized vertical with 4 radials at 8 feet

With this chapter we have fixed one of the big problems with previous designs: we have lengthened the whips for the element(s). In fact, we have substituted extra “arms” and long whips for the coils. No coils are necessary for 20 meters and up.

The other problem we have faced is the poor radial system. One sloping radial gives us a bizarre pattern and a generally poor return. Supplying four radials in place of that single radial makes a world of difference, as evidenced by the plots below. Even antennas at 8 feet perform very well with these extra radials.

9.3.1 Buddipole full-sized vertical with 4 radials for 10m at 8 feet


Figure 197 Buddipole full-sized vertical for 10m with 4 radials


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1 W3E1 0, 0, 96 W2E1 0, 0, 118 0.75 11 1 0

2 W1E2 0, 0, 118 0, 0, 198 0.5 11 1 0

3 W4E1 0, 0, 96 0, 69, 23 #12 11 1 0

4 W5E1 0, 0, 96 -69, 0, 23 #12 11 1 0

5 W6E1 0, 0, 96 0, -69, 23 #12 11 1 0

6 W1E1 0, 0, 96 69, 0, 23 #12 11 1 0

7 0, 0, 6 0, 0, 90 1 11 1 0


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Figure 198 SWR for BP full-sized vertical with 4 radials on 10m at 8 feet



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BP full-sized vertical on 10m with 4 radials BP Full-sized vertical on 10m with 4 radials

Figure 199 BP full-sized vertical with 4 radials on 10m at 8 feet over good ground


BP Full-sized vertical on 10m with 4 radial BP Full-sized vertical on 10m with 4 radials

Figure 200 Buddipole full-sized vertical, 4 radials on 10m at 8 feet over poor ground


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1 W3E1 0, 0, 96 W2E1 0, 0, 118 0.75 11 1 0

2 W1E2 0, 0, 118 0, 0, 209 0.5 11 1 0

3 W4E1 0, 0, 96 0, 81, 14 #12 11 1 0

4 W5E1 0, 0, 96 -81, 0, 14 #12 11 1 0

5 W6E1 0, 0, 96 0, -81, 14 #12 11 1 0

6 W1E1 0, 0, 96 81, 0, 14 #12 11 1 0

7 0, 0, 6 0, 0, 90 1 11 1 0

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BP Full-sized vertical on 12m with 4 radials BP Full-sized vertical on 12m with 4 radials



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1 W3E1 0, 0, 96 W2E1 0, 0, 118 0.75 11 1 0

2 W1E2 0, 0, 118 0, 0, 230 0.5 11 1 0

3 W4E1 0, 0, 96 0, 129, 36 #12 11 1 0

4 W5E1 0, 0, 96 -129, 0, 36 #12 11 1 0

5 W6E1 0, 0, 96 0, -129, 36 #12 11 1 0

6 W1E1 0, 0, 96 129, 0, 36 #12 11 1 0

7 0, 0, 6 0, 0, 90 1 11 1 0

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1 W3E1 0, 0, 96 W2E1 0, 0, 139 0.75 11 1 0

2 W1E2 0, 0, 139 0, 0, 251 0.5 11 1 0

3 W4E1 0, 0, 96 0, 152, 36 #12 11 1 0

4 W5E1 0, 0, 96 -152, 0, 36 #12 11 1 0

5 W6E1 0, 0, 96 0, -152, 36 #12 11 1 0

6 W1E1 0, 0, 96 152, 0, 36 #12 11 1 0

7 0, 0, 6 0, 0, 90 1 11 1 0

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1 W3E1 0, 0, 96 W2E1 0, 0, 182 0.75 11 1 0

2 W1E2 0, 0, 182 0, 0, 294 0.5 11 1 0

3 W4E1 0, 0, 96 0, 198, 36 #12 11 1 0

4 W5E1 0, 0, 96 -198, 0, 36 #12 11 1 0

5 W6E1 0, 0, 96 0, -198, 36 #12 11 1 0

6 W1E1 0, 0, 96 198, 0, 36 #12 11 1 0

7 0, 0, 6 0, 0, 90 1 11 1 0

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9.4 Buddipole full-sized vertical with 1 radial at 16 feet

The single radial version of these antennas is now moved up to 16 feet. All radials now descend at 45 degrees. We still have the bizarre patterns found at 8 feet.





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1 W3E1 0, 0, 192 W2E1 0, 0, 214 0.75 11 1 0

2 W1E2 0, 0, 214 0, 0, 294 0.5 11 1 0

3 W1E1 0, 0, 192 0, 69, 119 0.5 11 1 0

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1 W3E1 0, 0, 192 W2E1 0, 0, 214 0.75 11 1 0

2 W1E2 0, 0, 214 0, 0, 305 0.5 11 1 0

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1 W3E1 0, 0, 192 W2E1 0, 0, 214 0.75 11 1 0

2 W1E2 0, 0, 214 0, 0, 326 0.5 11 1 0

3 W1E1 0, 0, 192 0, 95, 97 0.5 11 1 0

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1 W3E1 0, 0, 192 W2E1 0, 0, 235 0.75 11 1 0

2 W1E2 0, 0, 235 0, 0, 347 0.5 11 1 0

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1 W3E1 0, 0, 192 W2E1 0, 0, 278 0.75 11 1 0

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9.5 Buddipole comparisons and conclusions

9.5.1 Gain and take-off angles of configurations

Below is a table summarizing the gain and take-off angle for the Buddipole configurations discussed above.

Buddipole Configuration Comparisons

Standard

BP

dipole

16 feet

Standard

BP

Loaded

Vertical

L

@ 8 feet

Standard

BP

Loaded

Vertical

L

@ 16 feet

Standard

BP

Loaded

Vertical

1 radial

16 feet

Long BP

Full-size

Vertical

4 radials

8 feet

Long BP

Full-size

Vertical

1 radial

16 feet

6.93 dBi 4.62 dBi 5.21 dBi 0.03 dBi 1.62 dBi 0.03 dBi 10m

30 deg 30 deg 20 deg 15 deg 20 deg 15 deg 10m







X 3.11 dBi 3.87 dBi 2.53 dBi 0.44 dBi 1.52 dBi 20m

X 70 deg 40 deg 25 deg 20 deg 20 deg 20m

Table 4 Buddipole gain and take-off angle summary

The dipole configurations have take-off angles too high for good DX. Further, they are difficult to match over 15m. Neither of these facts should be surprising.

The “L” configuration has two problems: it is awkward on the top of the mast with the weight significantly off-center, and it still has a very high take-off angle on 20m. The numbers do indicate that there may be some value in having the radials level instead of sloping, however.

The vertical configurations (loaded and unloaded) with a single radial provide low take-of angles and an interesting pattern. A vertical cannot have gain in one direction without


191

sacrificing power in another and this is evident from the plots. Additional sloping radials should smooth out the pattern while still retaining the low take-off angle.

9.5.2 Comparing Buddipole to Force-12 Sigma-5

This white paper began by analyzing the Force-12 Sigma-5. This section compares the full-sized vertical antenna built from the Buddipole at 8 feet with 4 radials. Both azimuth and elevation plots for these antennas on the bands 10-20m appear below. The Force-12 Sigma-5 always appears on the left; the full-sized Buddipole vertical always appears on the right.

In comparing these antenna plots we should examine the maximum gain, directivity, deep nulls in the patterns, and other aspects of the far field pattern. Since we are also doing this analysis for 100 Pound DXpeditions we should consider the weight and packing size of these antennas. (Also note that the Force-12 Sigma-5 is a multiple-band antenna reducing the time we spend doing antenna erection and the amount of coax required for deploying antennas for these five bands.)

The Buddipole deployed as a full-sized vertical with four sloping radials is about 1.5 dB better than the Force-12 Sigma-5 antenna on all the bands. The Buddipole also has a slightly lower take-off angle on each band. Putting these values in perspective, consider the power difference as a percentage. If the difference between two powers is 1.5 dB then the ratio between the two powers is:

If system A is 1.5 dB less than system B, then system A is putting out 70% of the power of system B. So, if we are putting out 100 watts in system B, we are only putting out 70 watts in system A. Considering that a factor of 4 is an S-unit, this is something like a quarter of an S-unit worth of difference. How much weight is this worth? How much space is this worth? These are the kinds of tradeoffs that are considered during 100 Pound DXpedition planning.

The plots comparing these antennas appear below.

% difference = 10 10

X dB


192

Force-12 Sigma-5 on 10m BP Full-sized vertical on 10m with 4 radials

Figure 237 Force-12 Sigma-5 vs. BP full-sized vertical on 10m azimuth

Force-12 Sigma-5 on 10m BP Full-sized vertical on 10m with 1 radial

Figure 238 Force-12 Sigma-5 vs. BP full-sized vertical on 10m elevation


193






194



Force-12 Sigma-5 on 15m BP full-sized vertical on 15m with 1 radial



195






196






197

10 SMALL ANTENNAS 10-20M CONCLUSIONS

Antennas mounted on or near the ground which are relatively light and inconspicuous are not going to have the same gain or pattern as a yagi at 70 feet. That said, the choices explored in this white paper: the TW Antennas Traveler, Force-12 Sigma-5, quarter-wave vertical with 16 radials, and full-sized Buddipole vertical, all offer relatively good performance while conforming to the other constraints of weight and size. The figure below arrays the four interesting configurations for 20 meters.

Antennas for 20m with elevation plots and relative power outputs

-1.99 dBi

30 degrees

-1.24 dBi

25 degrees

-0.05 dBi

25 degrees

0.44 dBi

20 degrees

57 watts 68 watts 89 watts 100 watts

TW Antennas

Traveler Force-12 Sigma-5 Quarter-wave

vertical 16 radials Buddipole full-sized

vertical with 4 radials

Figure 247 Comparing various 20m antenna options

The quarter-wave vertical falls below the Buddipole only because the feed point and radials are closer to the ground. Modeling shows that lifting the quarter-wave vertical higher provides similar characteristics to the Buddipole as specified. However, a 20-meter quarter-wave vertical can be held up by a relatively inexpensive (and very lightweight) 20-foot fishing pole. A 33-foot mast holding the antenna up high enough to equal the performance of the Buddipole is significantly heavier and more costly than the fishing pole. For 0.5 dB it probably isn’t worth it. Further, the quarter-wave vertical can be reduced to only 4 radials and the gain drops to -0.11 dBi. So, a vastly simpler antenna system (with 12 fewer radials) costs very little in performance.

The two compact vertical dipoles compare very well to the other full-sized antennas. Yes, there is some drop in gain, but it is not an S-unit, or even half-an-S-unit (though we get close to that on the TW Antennas Traveler). Concerns that these systems might be “elaborate dummy loads” are unfounded. These antennas perform fairly well on 20m and even better


198

on the higher bands. Certainly, they perform well enough to merit further consideration for inclusion in our kits.

The size, weight, and performance of the antenna is only part of the equation. Again, if we were to deploy 5 single-band antennas the weight and space requirements for those items would likely exceed that of a single mult-band antennas. Further, a multiband antenna requires a single run of coax. Five 50-foot runs of RG-8X weighs 10 pounds. One 50-foot run of RG-213 weighs under 6 pounds. Losses in the antenna system might be partially offset by fewer losses in the feed line—all while meeting the same weight and space budget. In this case, at 2:1 SWR and at 30 MHz, the loss of the very lightweight coax is about 1 dB and the loss of the RG-213 is about half that (0.53 dB). It is important to evaluate whole

systems of things and not just component pieces.

The Buddipole Deluxe Package comes with two coils, two arms, two (short) whips, tripod, and mast. If the intention is to only use this antenna on 20 meters and above, I would recommend removing the coils from the package and replacing them with two additional arms, two additional long whips (one as a spare), and enough wire to create four elevated radials as described here. Perhaps Buddipole Antennas should sell such a configuration as the “BuddiVert” or some similar name. The elevated full-sized quarter-wave vertical with the large diameter element and elevated radials performs very well, is configurable for 5 bands, and should weigh-in at less than 9 pounds.

The two small vertical dipoles evaluated exceeded expectations. Though the performance was below the various single-band antennas it was close enough to strongly consider inclusion on a 100 Pound DXpedition because of the convenience of supporting 5 bands with one unit, and the weight and space savings for having one radiator and one coax feed for five bands. Perhaps the weight savings on these bands could allow bringing enough materials to support another band like 80 meters. If the sacrifice of 1 dB on some bands allowed operation on another band that would otherwise be unavailable, this seems like a worthwhile trade-off. Again, with no weight or size limits we would not need to make such compromises. But, this approach to DXpeditioning embraces cold calculations and give-and-take for all aspects of a portable station.

Discussions of these small antennas have largely ignored a major influence on their performance: the effects of ground. This is addressed in the next chapter.


199

11 THE EFFECTS OF GROUND

The far field plots for the antennas discussed have been made over two specified types of ground:

• Good ground (0.005 S/m, dielectric constant 13)

• Poor ground (0.001 S/m, dielectric constant 5)

These are but two of the infinite combinations of ground shapes and conductivity that may appear under our antenna systems. There is a large range of ground types to consider from “free space” (no ground) to a “perfect ground” that has infinite conductivity.

The effects of ground are best shown with far field plots. The two plots “good ground” and “poor ground” tell only part of the story. What if we were to put the antenna on the beach (over sand) but right on the ocean’s edge? What if we place the antenna over the end of a dock on the ocean or a fresh water lake? How about mounting the antenna on the roof of a high building? The following sections will investigate the effects of ground on various antenna systems.

11.1 Long ground radials for the Force-12 Sigma-5

All of these situations will produce significantly different results than have been shown with our “standard” two plots of “good” and “poor” ground. We will use the Force-12 Sigma-5 vertical dipole antenna on 20m for our examination of the effects of ground. After seeing plots like the following, it is difficult not to change the way you look at the ground beneath antennas.


200

Free space High building Poor ground

Sandy dry ground Good ground Rich soil

Fresh water Salt water Perfect ground

Force-12 Sigma-5 on 20m over various ground types

Figure 248 Force-12 Sigma-5 on 20m over a range of ground types


201

The antenna over perfect ground sends a good portion of its energy right down the surface of the perfect ground. The take-off angle is even shown as zero degrees. The antenna positioned on the surface of salt water does nearly as well. (Hence, the popular notion that the best QTH is the mountain-top with a salt water pond on top.) Other grounds produce increasing take-off angles and reduced gains.

An interesting exotic location may be on sandy and dry ground. What can be done that is relatively easy and requires only lightweight materials to combat these losses to a poor ground? Short of building a salt pond beneath the antenna extending several wavelengths, the easiest way to combat this problem is with a ground wire system.

Assume the antenna is positioned over poor ground (0.001 S/m, dielectric constant 5). Adding one wavelength wires on one inch above the ground in a radial pattern beneath the antenna substantially reduces the ground loss. Note that these wires are not even connected to the antenna! Consider the following far field plots with varying radial configurations.

No radials 8 radials 16 radials

-2.29 dBi -0.81 dBi 0.88 dBi

Baseline over poor ground 1.48 dB better 3.17 dB better!

Force-12 Sigma-5 vertical dipole antenna on 20m above radial wires

Figure 249 Full-wave radials used to reduce ground loss

The 16 radial configuration doubles the effectiveness of the antenna system. It requires over 1100 feet of wire to complete the array (70 feet x 16 radials = 1120 feet) but the wire diameter can be very small. AWG #26 wire was specified in the model. A spool of such wire weighs only a couple of pounds. What other two pound accessory can you think of that would double the effectiveness of your antenna system? The following plots show effects on the other bands.


202

Force-12 Sigma-5 on 10m no radials Force-12 Sigma-5 on 10m with 16 radials

Figure 250 Force-12 Sigma-5 on 10m compares no radials and 16 radials




203






204

A summary of the benefits of these 67 foot radials under this antenna is shown in the table below:

Band No radials

With 16 radials 67

feet long Difference

10m -0.45 dBi 1.08 dBi 1.53 dB

12m -0.79 dBi 0.56 dBi 1.35 dB

15m -1.20 dBi 1.07 dBi 2.27 dB

17m -1.59 dBi 0.44 dBi 2.03 dB

20m -2.29 dBi 0.88 dBi 3.17 dB

Table 5 Force-12 Sigma-5 gain comparisons 16 67-foot radials vs. no radials

The lower bands had fewer problems with the lossy ground so the radials were not as important to their performance. But, the 20m configuration which had suffered considerably from the poor ground picked up over 3 dB (as discussed). The fact that a single radial system can be used to increase the performance of five bands is another argument for the consideration of a multiband antenna like the Force-12 Sigma-5 or the TW Antennas 2010 Traveler.

How effective are these radials? The radials help produce results that exceed the rich soil identified above and approach results obtained when positioned over fresh water. Again, it is important to emphasize that we have not altered the antenna in any way; we have only altered the environment in which the antenna operates.

11.2 The effects of radial length on a vertical dipole

The ARRL Antenna Book discusses extensively the effects of ground for a quarter wave vertical antenna. This not what is under discussion here. The vertical dipole antenna behaves differently than its quarter wave vertical monopole cousin. Therefore, advice given for the quarter wave monopole cannot be directly applied here. For example, the advice to limit radial length to 0.1 if there are 16 radials or fewer does not apply here. Consider the

following.


205

Over 16 radials length 8 feet Over 16 radials length 16

feet

Over 16 radials length 33

feet

Force-12 Sigma-5 on 20m

Figure 254 Varying radial lengths for 16 radials over a vertical dipole

Sixteen radials at varying lengths of 8, 16, and 33 feet provide the above results. Note that the 33 foot radial set actually outperforms the 67 foot radial set described previously! (The 33 foot radials have 1.08 dBi of gain; the 67 foot radials have 0.89 dBi of gain.)

What happens if the number of radials is doubled? Consider the following with differing lengths of 32 radials under a vertical dipole antenna in Figure 255. Doubling the number of 8 foot radials does nearly nothing to our gain (-2.14 dBi vs. -2.07 dBi). There is a very small pickup in gain by doubling the number of 16 foot radials (-1.75 vs. -1.48). The 33 foot radials (about a half-wavelength in length for 20m) also shows a very small pickup in gain (1.08 dBi vs. 1.43 dBi).

Doubling the number of radials did very little to help the gain. Certainly, the time and effort to lay 16 extra radials for a gain of about 0.3 dB seems wasted.


206

Over 32 radials length 8 feet Over 32 radials length 16

feet

Over 32 radials length 33

feet

Force-12 Sigma-5 on 20m

Figure 255 Varying radial length for 32 radials over a vertical dipole

Computations were performed for the five bands over this new set of radials (16 by 33-feet) which yielded the following new data.

Band No radials

With 16 radials 33

feet long Difference

10m -0.45 dBi 1.49 dBi 1.94 dB

12m -0.79 dBi 0.62 dBi 1.41 dB

15m -1.20 dBi -0.36 dBi 1.56 dB

17m -1.59 dBi 0.06 dBi 1.65 dB

20m -2.29 dBi 1.08 dBi 3.37 dB

Table 6 Force-12 Sigma-5 gain comparisons 16 33-foot radials vs. no radials

The numbers hint at something going on here other than a simple linear relationship between gain and radial length. The table below shows data for radial lengths 8 feet through 48 feet in roughly four-foot increments. The bands are arrayed in the vertical axis; the lengths of each of the 16 radials is shown in the horizontal axis.


207

10 -0.45 0.23 0.55 1.43 0.70 0.43 0.92 1.49 1.04 0.85 1.14 1.37

12 -0.78 -0.66 -0.32 0.75 1.21 0.16 -0.35 0.62 1.68 1.38 0.58 0.23

15 -1.20 -1.09 -0.87 -0.25 1.08 1.03 0.13 -0.36 -0.20 0.93 1.63 1.06

17 -1.59 -1.48 -1.30 -1.30 -0.07 1.17 0.95 0.06 -0.25 -0.38 0.07 1.13

20 -2.29 -2.14 -1.97 -1.75 -1.39 -0.68 0.53 1.08 0.68 0.12 -0.22 -0.37

0 8 12 16 20 24 28 33 36 40 44 48

Table 7 Force-12 Sigma-5 computed gains with 16 radials of varying length

The table below has gains relative to the antenna over no radials. The two highest gain values for each band are shown in bold.

10m 0.00 0.68 1.00 1.88 1.15 0.88 1.37 1.94 1.49 1.30 1.59 1.82

12m 0.00 0.12 0.46 1.53 1.99 0.94 0.43 1.40 2.46 2.16 1.36 1.01

15m 0.00 0.11 0.11 -0.25 1.08 1.03 0.13 -0.36 -0.20 0.93 1.63 1.06

17m 0.00 0.11 0.29 0.29 1.52 2.76 2.54 1.65 1.34 1.21 1.66 2.72

20m 0.00 0.15 0.32 0.54 0.90 1.61 2.82 3.37 2.97 2.41 2.07 1.92

0 8 12 16 20 24 28 33 36 40 44 48

Table 8 Relative gain (dB) of Force-12 Sigma-5 over 16 radials of various lengths

The numbers appear to be cyclic in the table and a graphing of those values confirms that pattern. The graph below shows this relationship.


208

Figure 256 Radial length vs. gain for 16 radials under a Force-12 Sigma-5

Multiples of half-wave lengths per band appear to be the most effective. For 10m the lengths 16 feet, 33 feet, and 48 feet all have high gains and are multiples of a half-wave length. For 12m the lengths 19 feet and roughly 38 feet have good gains. For 15m radial lengths of 22 feet and 44 feet, which are also multiples of half-wave lengths, have good gain. The pattern appears to hold for 17m and 20m as well.

11.3 Dual-length radials

The alternative to single-length radials is to use two (or more) differing lengths of radials within the system. This section discusses using two lengths. Results from the above indicate that 24-foot radials provide good performance on bands 15m and 17m, while 33-foot radials provide good gain on 10m and 20m. Choosing these two radial lengths means only 12m was forced to compromise (with the anticipated gain now only 0.94 instead of 1.99 as would be yielded from a 20-foot radial). The models below show the effects of this two radial-length system. We have eight radials at 33 feet and 8 others at 20 feet. All radials are evenly spaced with the shorter radials interspersed with the longer ones.


209

Figure 257 16 radials alternating lengths of 20 feet and 33 feet under Force-12 Sigma-5

The comparisons between this configuration and the configuration previously described with 16 uniform length 33 foot radials should acknowledge that shortening half of the long radials to only 20 feet will likely reduce the gain on the 20 meter band. Indeed, this is the case as evidenced by the table below.

With 8@20-feet + 8@33 feet With 16@33-feet

Comparing

both

Band No radials Gain Relative gain Relative Gain relative gains

10 -0.45 +0.98 +1.43 +1.94 +0.51

12 -0.78 +1.22 +2.00 +1.40 -0.60

15 -1.20 -0.38 +0.82 -0.36 -1.18

17 -1.59 +0.87 +2.46 +1.65 -0.81

20 -2.29 -0.85 +1.44 +3.37 +1.93

Table 9 Comparing gains for the 16@33-feet and 8@20-feet + 8@33-feet

configurations

Nearly 2 dB was lost on 20m by shortening half of these radials. So, if the purpose of the exercise was to pump up 20m then this is clearly an inferior solution to the 16 full-sized 33-foot radials. But, the pickup of gain on 12m, 15m, and 17m is interesting—especially since the new configuration uses much less wire (104 feet less).

The model for this configuration appears below (for the Force-12 Sigma-5 on 20m).


210

EZNEC+ ver. 5.0

Force-12 Sigma-5~20m 16x33+20 9/13/2007 9:16:22 PM




--------------- WIRES ---------------


Insulation

Conn. X Y Z Conn. X Y Z Diel C

Thk(in)

1 W4E1 0, 0, 29 W2E1 0, 0, 35 0.5 6 1 0

2 W1E2 0, 0, 35 W3E1 0, 0, 126 1 22 1 0

3 W2E2 0, 0, 126 W6E1 0, 0, 132 0.5 6 1 0

4 W5E1 0, 0, 29 0, -24, 29 0.5 6 1 0

5 W1E1 0, 0, 29 0, 24, 29 0.5 6 1 0

6 W7E1 0, 0, 132 0, -24, 132 0.5 6 1 0

7 W3E2 0, 0, 132 0, 24, 132 0.5 6 1 0

8 W9E1 0, 0, 1 0, 396, 1 #26 40 1 0

9 W10E1 0, 0, 1 -280.01,280.014, 1 #26 40 1 0

10 W11E1 0, 0, 1 -396, 0, 1 #26 40 1 0

11 W12E1 0, 0, 1 -280.01,-280.01, 1 #26 40 1 0

12 W13E1 0, 0, 1 0, -396, 1 #26 40 1 0

13 W14E1 0, 0, 1 280.014,-280.01, 1 #26 40 1 0

14 W15E1 0, 0, 1 396, 0, 1 #26 40 1 0

15 W16E1 0, 0, 1 280.014,280.014, 1 #26 40 1 0

16 W17E1 0, 0, 1 92, 222, 1 #26 40 1 0

17 W18E1 0, 0, 1 -91.924,222.032, 1 #26 40 1 0

18 W19E1 0, 0, 1 -222, 92, 1 #26 40 1 0

19 W20E1 0, 0, 1 -222.03,-91.924, 1 #26 40 1 0

20 W21E1 0, 0, 1 -92, -222, 1 #26 40 1 0

21 W22E1 0, 0, 1 91.924,-222.03, 1 #26 40 1 0

22 W23E1 0, 0, 1 222, -92, 1 #26 40 1 0

23 W8E1 0, 0, 1 222.032,91.9239, 1 #26 40 1 0

Total Segments: 698

-------------- SOURCES --------------



1 2 50.00 52.27 12 1 0 I

-------------- LOADS (RLC Type) --------------



1 2 47.00 47.73 11 Open 3.42 2 14.2 Par


211

2 2 55.00 56.82 13 Open 3.42 2 14.2 Par

3 2 50.00 52.27 12 Short 0.52 Short 0 Ser





--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.001 5 0 0

An alternative configuration would be 8 radials at 33 feet and 8 radials at 24 feet. The gain results for that configuration appear below.

With 8@24-feet + 8@33

feet With 16@33-feet

Comparing

both

Band No radials Gain Relative gain Relative Gain relative gains

10 -0.45 +0.79 +1.24 +1.94 +0.70

12 -0.78 +0.57 +1.35 +1.40 +0.05

15 -1.20 -0.20 +1.00 -0.36 -1.36

17 -1.59 +0.50 +2.09 +1.65 -0.44

20 -2.29 +0.43 +2.72 +3.37 +0.65

Table 10 Comparing gains for the 16@33-feet and 8@24-feet + 8@33-feet

configurations

There are minor reductions in gain compared to the 33-feet+20-feet radial pattern above on 10m (0.19 dB), 12m (0.65 dB), and 17m (0.38 dB). Gains relative to the other configuration are found on 15m (0.18 dB), and 20m (1.28 dB). This new configuration still suffers on 10m and 20m compared to the 16 radials of 33 feet, but shows better performance on all other bands.

Returning to the comparison with the original baseline, the antenna situated over very poor ground, the relative gains with these radials are somewhere between 1 dB for 15m to 2.72 dB for 20m. Again, this is achieved with less than 500 feet of very light wire. The question is posed again: what other mechanism increases the performance of an antenna system on five bands yet weighs under a pound?

Adding radials beneath the Force-12 Sigma-5 brings its performance to near parity with the Buddipole vertical with four elevated radials. In fact, radial lengths can be selected which would provide performance from this vertical dipole exceeding that of the Buddipole. Ground-mounted radials are easier to install (though there are more of them) since we do not need to rig a system to elevate them. Finally, we get all the flexibility and coax weight savings of the multiple band antenna with this arrangement. If space is available to lay out these radials, a multi-band vertical dipole with radials is a strong contender.


212

12 BALCONY ANTENNAS

12.1 Problem description

Not every evening will be spent in a spacious villa isolated on some island paradise. Some evenings will be spent in a small hotel room. If you’re lucky, you might have a balcony a little larger than a postage stamp from which you can deploy an antenna. This chapter will discuss some options for this situation: operating from a high balcony.

There are a number of problems with such a venue. First, the balcony is likely to be very small, which limits the kinds of things that can be deployed. Secondly, any antenna we attempt to deploy will be very close to the building and very far from the ground. Finally, except perhaps for the railing on the balcony, there are few places to attach or anchor antenna pieces.

I would be remiss if I didn’t mention one of the most important things about balcony antennas: safety. Dropping even a small item from a balcony on to an unsuspecting person at ground level can result in serious injury or death. Please secure all items when deploying an antenna system on a balcony. I routinely tie short lengths of Dacron rope to pieces to be sure that anything that breaks loose (or simply breaks) will not fall to the ground.

Finally, the models included in these discussions will not consider the largest and most influential items in our antenna system. The building with its bricks, concrete, rebar, and stone will be ignored. Plots for far field energy distribution will therefore be absolutely best-case. Results are likely to be much worse.

These antennas do not perform well. How can they?! They are probably shortened vertical variants with poor radial systems positioned next to large building that will have detrimental affects on the pattern and overall efficiency. But, even a poor antenna radiates some signal, and some is better than none. I’ve made many contacts using a balcony antenna and had a great deal of fun doing it.

12.2 20 meters

It is unlikely that you will be making 160m or 80m contacts from a balcony antenna. But, 40m, 30m, and 20m systems are possible with a minimum of fuss. This section discusses some 20m antenna ideas.

12.2.1 Fishing pole horizontal antenna

As with any of these antennas, the main problem is to get the main radiator away from the building and into free space as much as possible. The three general approaches for this are to have a pole or mast extend a wire away from the building, use a mast such as that which comes with a Deluxe Buddipole system to move the antenna and feed point away from the building, or simply attach a radiator directly to the railing of the balcony. The antenna discussed here uses a small collapsible fishing pole to hold a wire.


213

A Cabela’s Telescopic Panfish Pole (CP-14) is a 14 foot lightweight pole that collapses down to 15.5 inches. It weighs just a few ounces. It is small enough that it can be packed into a suitcase or briefcase along with the wire it supports.

Figure 258 Cabela’s 14 foot collapsible panfish pole

The general idea for this antenna design is to use this pole to route the main radiating wire out from the balcony for up to 12 feet (leaving the first 2 feet of the pole on the balcony to secure it). The remaining wire for the radiator will droop down off the end of the pole.

The small balcony prevents an elaborate radial system. Instead, a single wire is dropped from the feed point straight down, and two other wires are routed around the periphery of the balcony. The antenna view below illustrates this arrangement.


214

Figure 259 Balcony fishing pole antenna for 20m

The model for this antenna appears below.

EZNEC+ ver. 5.0

Balcony fishing pole 20m 9/14/2007 8:01:14 PM




--------------- WIRES ---------------



1 W3E1 0, 0, 2000 W2E1 0, 120, 2000 #16 6 1 0

2 W1E2 0, 120, 2000 0, 120, 1910 #16 6 1 0

3 W7E1 0, 0, 2000 W4E1 -60, 0, 2000 #16 6 1 0

4 W3E2 -60, 0, 2000 W5E1 -60, -60, 2000 #16 6 1 0

5 W4E2 -60, -60, 2000 W6E1 -10, -60, 2000 #16 6 1 0

6 W5E2 -10, -60, 2000 -10, -30, 2000 #16 6 1 0

7 W11E1 0, 0, 2000 W8E1 60, 0, 2000 #16 6 1 0

8 W7E2 60, 0, 2000 W9E1 60, -60, 2000 #16 6 1 0

9 W8E2 60, -60, 2000 W10E1 10, -60, 2000 #16 6 1 0

10 W9E2 10, -60, 2000 10, -30, 2000 #16 6 1 0

11 W1E1 0, 0, 2000 0, 0, 1790 #16 6 1 0


215

Total Segments: 66

-------------- SOURCES --------------



1 1 0.00 8.33 1 1 0 I

No loads specified





--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.001 3 0 0

The SWR for this antenna can be reasonable assuming that the main radiator is not being detuned by the graphite pole. Lengthening or shortening the dropped (vertical) radial can usually bring the antenna into tune.

Figure 260 SWR for 20m fishing pole balcony antenna

The far field plot for this antenna appears below. Again, the effects of the building are not represented so at least half of the far field (that faces the building) will not be accurate.


216

20m fishing pole balcony antenna 20m fishing pole balcony antenna

Figure 261 20m fishing pole balcony antenna 2D far field pattern

The 3D far field plot appears below. The ridges appearing in the elevation plot above are vivid in the 3D plot.

Figure 262 20m fishing pole balcony antenna 3D far field pattern


217

13 ANTENNAS FOR 6M

Though most DX work will be done on HF, the Magic Band can also bring some joy. This chapter explores some small, easy to pack alternatives for the 6m band.

13.1 Hentenna from the Buddipole Users Group

The 6m Hentenna appeared on the Buddipole Users Group Yahoo! group in September of 20007. It was introduced by Katsuya Okamura (JE3NJZ/KH2E) and Takashi Kaida (JE1HJA/N3JZ). The design uses standard Buddipole parts including

• A center Tee such as the VersaTee

• Two 22 inch arms

• Two stainless steel whips (5.5 feet)

• Two long whips (9.3 feet)

• Two “IT” adapters (available from Buddipole Antennas)

• Two knobs from a rotating arm kit (available from Buddipole Antennas)

Additionally, two 100 cm (39.4 inch) wire “jumpers” with gripping clips are used to complete elements 4 and 7 shown in Figure 263. The entire antenna can be put on top of a standard Buddipole tripod and mast system. The model for this antenna assumes usage of the 16 foot mast.

The antenna is fed directly to the center Tee with 50 ohms. No special impedance matching or loading were included in the model. The schematic view of this antenna appears below.

Figure 263 Hentenna for 6m antenna view

The SWR curve for this antenna over the entire 6m band is shown below.


218

Figure 264 Hentenna for 6m SWR

As the SWR curve shows, this antenna provides a good match for most of the 6m band.

The EZNEC model data for this antenna follows.

EZNEC+ ver. 5.0

Hentenna from BUG 9/14/2007 12:43:38 AM




--------------- WIRES ---------------



1 W2E1 -22, 0, 192 W3E1 22, 0, 192 0.75 11 1 0

2 W5E1 -22, 0, 192 W4E1 -19.7, 0, 141 0.5 11 1 0

3 W6E1 22, 0, 192 W4E2 19.7, 0, 141 0.5 11 1 0

4 W2E2 -19.7, 0, 141 W3E2 19.7, 0, 141 #16 11 1 0

5 W1E1 -22, 0, 192 W7E1 -22, 0, 270.75 0.5 11 1 0

6 W1E2 22, 0, 192 W7E2 22, 0, 270.75 0.5 11 1 0

7 W5E2 -22, 0, 270.75 W6E2 22, 0, 270.75 #16 11 1 0

Total Segments: 77

-------------- SOURCES --------------




219

1 1 50.00 50.00 6 1 0 I

No loads specified





--------------- MEDIA ---------------


(S/m) (in) (in)

1 0.005 13 0 0

This antenna produces a pattern of good gain at a reasonably low angle of radiation broadside to the antenna as illustrated in the three-dimensional Far Field plot shown below.

Figure 265 6m Hentenna Far Field Plot (3D)

The 2D far field plots for this antenna appear in the figure below.


220

Hentenna from Buddipole parts for 6m Hentenna from Buddipole parts for 6m

Figure 266 Hentenna for 6m Far Field Plot over good ground

This antenna is light, provides 10 dBi of gain, and has a nice symmetrical pattern that would make the antenna easy to aim in the field. Because the antenna is made from Buddipole parts, one could construct this antenna or an afternoon or a day and then convert it back to HF use for more traditional DXpeditioning work. Though it is also possible to make a Yagi from the Buddipole parts, this antenna configuration is worth a try.


221

14 FINAL COMMENTS TO VOLUME 1

This white paper discussed a small number of antennas and antenna configurations that can be created from simple materials or from popular commercial offerings. There is a great deal of lore and superstition surrounding antennas within the amateur radio circles. Some of these tales provide useful guidance; others are nonsensical. Sorting them out may not be easy but it is well worth one’s time to try. This white paper is a small step towards that goal.

I owned the Force-12 Sigma-5 for several years. I sold it in the Spring of 2008 because it did not travel as well as I had hoped it might. I suspect the ham that bought it is putting it to good use in some semi-permanent installation. I note here that Force-12 (the company) has been purchased and the new owner seems keen to revamp the product line, increase quality, and streamline customer service. Force-12 antennas have a history of helping make DXpeditions successful. It is a company worth watching.

I have purchased the TW Antennas TW2010 antenna system. This system has a very rugged carry bag that holds the antenna components, controller cable, 50 feet of coax, the controller box, and other small items. The X-base can ride on top of the bag, though it adds considerable weight. Though the analysis here shows the antenna to be slightly inferior in performance to the Sigma-5, it is much more rugged, breaks down smaller, packs easily, and has a much more polished look and feel. With a suitable wire ground system as described in this white paper, this could be a very good performer on a DXpedition—even over poor ground.

I have deployed fishing pole vertical antennas with two or four elevated radials for band 80-meters, 40-meters (which doubles as a nice 15-meter antenna), 20-meters, and 17-meters. These antennas consist of little more than a fishing pole, center insulator, and wires. Assembly at the DXpedition site is little more than unwinding the wires, taping the vertical section (and its Dacron rope leader) to the top of a fishing pole, standing the fishing pole up and lashing it to a fence post or small tree (or guying it), and stretching out the elevated radials. These antennas, especially the 80-meter and 40-meter versions, can be deployed off a second, third, or even fourth floor roof area to get the antenna well in the clear and the radials high off the ground. These antennas perform very well and weigh next to nothing. Though low-band antennas are out of the scope of this white paper, I will recommend this approach here.

The Buddipole antenna systems perform very well as evidenced by this analysis. And, while the dipole configuration was disparaged in the initial discussions, that configuration can be very effective if deployed high above the ground. If, say, a 16 foot mast is extended above a roofline 30 feet high, then the antenna is now at 46 feet—a big difference from the 16 foot levels discussed here. As usual, anything written in a book or white paper like this must be used within the context of its discussion. Just because a Buddipole dipole will not perform well at 8 feet does not mean that a similarly configured system will not perform extremely well if somehow deployed in the clear at a much greater height. How much better? Anyone with access to EZNEC or other modeling programs can use the models supplied with this white paper to make that determination. Feel free to use, edit, and explore the model data presented here to learn more about these antenna systems in situations not explored here.


222

Weight, bulk, and length affect the ability to transport equipment for 100 Pound DXpeditions. When investigating options for antennas always keep in mind that the components must eventually fit into either a regular checked bag, or a hard-sided golf bag if it is to travel on a commercial airliner. The Sigma-5 antenna did not have a carry case available for it when I purchased the unit. Further, I never found a case suitable for its oddly-shaped pieces. This is the primary reason why that antenna was sold.

The TW Antennas TW2010 does have a case available that is both rugged and roomy—accommodating everything needed for the deployment of the antenna except the base. This make the antenna attractive for this purpose.

The Buddipole systems also have cases available. Three different sizes of cases can be obtained from Buddipole antennas: a small rectangular case for the mini-Buddipole or Buddistick, a short case (about two feet long), and a long case (about four feet long). The rectangular case and short case can fit easily into a regular checked bag; the long case drops into a hard-sided golf bag easily.

Many of the interesting places to go have very poor ground beneath them. Hawaii, barrier islands around the US, and the islands of the Caribbean all have this issue in common. While advertised specifications for an antenna may make it look like a solid performer, it is best to do your own analysis and model the unit over very poor ground to see what effect, if any, this ground may have. It doesn’t matter if the antenna performs extremely well over salt water if your operating location is over dry sand.

Finally, though many of these destinations are barren and have few high structures that can be utilized for antenna supports, there are exceptions. If the property you are using has a high balcony then use it. If there are trees present, consider stringing a wire antenna. Though many times you will be the tallest thing in the vicinity, it will not always be so. Leverage roof lines, trees, high decks and verandas, and any other on-site resources available. Remember: higher is typically better than lower, and in the clear is better than in the clutter.

I hope that this will be the first of many such investigations. And, I hope that anyone who reads this finds at least some of it useful or interesting. See you on the bands. 73!

Scott (NE1RD)


223

APPENDIX A BUDDIPOLE COIL INDUCTANCES

Turn X(L) Turn X(L)

1 0.07 21 10.23

2 0.27 22 10.85

3 0.55 23 11.48

4 0.89 24 12.11

5 1.29 25 12.75

6 1.72 26 13.38

7 2.19 27 14.02

8 2.68 28 14.66

9 3.20 29 15.30

10 3.73 30 15.94

11 4.28 31 16.59

12 4.84 32 17.24

13 5.41 33 17.89

14 5.99 34 18.53

15 6.57 35 19.19

16 7.17 36 19.84

17 7.77 37 20.49

18 8.38 38 21.14

19 8.99 39 21.80

20 9.61 40 22.45


224

BUDDIPOLE LOW BAND COILS

Turn X(L) Turn X(L)

1 0.11 27 82.47

2 0.45 28 88.69

3 1.02 29 95.14

4 1.81 30 101.82

5 2.83 31 108.72

6 4.07 32 115.84

7 5.54 33 123.20

8 7.24 34 130.78

9 9.16 35 138.58

10 11.31 36 146.61

11 13.69 37 154.87

12 16.29 38 163.36

13 19.12 39 172.07

14 22.17 40 181.01

15 25.45 41 190.17

16 28.96 42 199.56

17 32.69 43 209.17

18 36.65 44 219.02

19 40.84 45 229.09

20 45.25 46 239.38

21 49.89 47 249.90

22 54.75 48 260.65

23 59.84 49 271.62

24 65.16 50 282.82

25 70.71 51 294.25

26 76.47 52 305.90


225

REFERENCES

ARRL. More Wire Antenna Classics. American Radio Relay League, 2002. Buddipole Users Group (BUG), http://groups.yahoo.com/group/buddipole Cain, James D. Yasme: The Danny Weil and Colvin Radio Expeditions. American

Radio Relay League (ARRL), 2003. Cebik, L. B. Arrl Antenna Modeling Course. Newington, CT: American Radio Relay

League, 2002. Christman, Al. "A Study of Elevated Radial Ground Systems for Vertical Antennas (Part

1)." The National Contest Journal Vol 33 No 1 (2005): 19-22. Christman, Al. "Compact Four-Squares." The National Contest Journal Vol 32 No 4

(2004): 10-12. Christman, Al. "Verticals By the Sea." The National Contest Journal Vol 33 No 4 (2005):

9-12. Christman, Al. "A Study of Elevated-Radial Ground Systems for Vertical Antennas (Part

2)." The National Contest Journal Vol 33 No 2 (2005): 17-20. Christman, Al. "Verticals By the Sea (Part 2)." The National Contest Journal Vol 33 No

5 (2005): 4-6. Devoldere, John. Arrl ON4UN's Low Band Dxing. American Radio Relay League

(ARRL), 2005. Heyerdahl, Thor. Kon-Tiki: Across the Pacific in a Raft. Pocket, 1990. Heys, John D. Practical Wire Antennas. Radio Society of Great Britain, 1989. Kleinschmidt, Kirk A. Stealth Amateur Radio: Operate From Anywhere. AARL, 1999. McCoy, Lew. Lew Mccoy on Antennas. Hicksville, New York: CQ Communications, Inc,

1994. Morin, Jodi. ARRL s Wire Antenna Classics. Amer Radio Relay League, 1999. Moxon, L.A. HF Antennas for All Locations. Amer Radio Relay League, 1993. Orr, WIlliam I. The W6SAI HF Antenna Handbook. Hicksville, NY: CQ Communications,

Inc, 1996. ARRL's Vertical Antenna Classics. Edited by Bob Schetgen. American Radio Relay

League (ARRL), 1995. Sevick, Jerry. Transmission Line Transformers. Raleigh, NC: Scitech Publishing, Inc,

2001. Sevick, Jerry. The Short Vertical Antenna and Ground Radial. Hicksville, NY: CQ

Communications, Inc, 2003. Sterba, Kurt N. Aerials II. Worldradio, Inc, 1993. The ARRL Antenna Book 21st Edition. Edited by R. Dean Straw. Newington, CT:

American Radio Relay League (ARRL), 2007. Sturba, Kurt N. "Radial Question." WorldRadio Year 36 No 10 (2007): 52. Sturba, Kurt N. "Radiation Resistance." WorldRadio Year 37 No 1 (2007): 49. Sturba, Kurt N. "Short Vertical." WorldRadio Year 36 No 5 (2006): 52.


226

Sturba, Kurt N. "Efficiency." WorldRadio Year 37, Issue 3 (2007): 52. The ARRL Handbook. Edited by Mark J. Wilson. Newington, CT: American Radio Relay

League (ARRL), 2006.

Additional resources were helpful in the construction of this work including:

• Images from the http://www.timewave.com web site for the AntennaSmith device and plots created with the device. Those images are used without permission.

• Cabelas (http://www.cabelas.com) sells inexpensive Black Widow fishing poles used on 100 Pound DXpeditions for vertical antennas and balcony radiators.

• The Team Vertical story (http://www.k2kw.com/tv.html) provided some of the impetus for the significant research done for this paper.

• The Microlite Penguin DXpedition team led by DX legends like Bob Alphin (K4UEE) often used half-wave vertical dipoles. A great deal can be learned by watching the DXpedition videos available from Bob Alphin (http://www.k4uee.com) or through DXvideos.com (http://www.dxvideos.com).

• This work would not have been possible without a program such as EZNEC version 5.0 by Roy W. Lewallen. Version 5.0.7 of EZNEC+ was used for all antenna modeling work. More information about this product is available from http://www.eznec.com

• Many ham radio products have on-line communities supporting them. The Buddipole has the Yahoo! group http://groups.yahoo.com/group/Buddipole which has over 3000 members.

This white paper covers only a fraction of the antennas investigated on 100 Pound Dxpeditions. More information about the 100 Pound DXpedition and works like this will be made available on NE1RD’s home page http://www.bsandersen.com .

Change log

1.00 1.01: Wire diameter comparisons in section 6.4 had the formula for wire circumfrence goofed up (dividing the diameter by 2 when that was unnecessary). In section 9.5.2 the sentence “So, if we are putting out 100 watts in system B, we are only putting out 70 watts in system B.” should read “So, if we are putting out 100 watts in system B, we are only putting out 70 watts in system A.” (and now does).

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Antennas for 100 Pound DXpeditions - | NE1RD ~ Home · ANTENNAS FOR 100 POUND DXPEDITIONS 8.2.4 Buddipole Vertical with L-arm radial for 17m at 8 feet.....108