End-Fed Antenna Length Study Amateur Bands Low Hi Freq Freq 3.500 4.000 7.000 7.300 10.100 10.150 14.000 14.350 18.068 18.168 21.000 21.450 24.890 24.990 28.000 29.700

Chart computes antenna lengths (feet) in increments of 1/8 wave for the Band Centers wave length in increments of 1/8 wave: 1 2 3 4 0.125 0.250 0.375 0.500 31.200 62.400 93.600 124.800 16.364 32.727 49.091 65.455 11.556 23.111 34.667 46.222 8.254 16.508 24.762 33.016 6.458 12.915 19.373 25.831 5.512 11.025 16.537 22.049 4.691 9.383 14.074 18.765 4.055 8.111 12.166 16.222

Band 80 40 30 20 17 15 12 10

Band Center 3.750 7.150 10.125 14.175 18.118 21.225 24.940 28.850

5 0.625 156.000 81.818 57.778 41.270 32.288 27.562 23.456 20.277

6 0.750 187.200 98.182 69.333 49.524 38.746 33.074 28.148 24.333

7 0.875 218.400 114.545 80.889 57.778 45.204 38.587 32.839 28.388

8 1.000 249.600 130.909 92.444 66.032 51.661 44.099 37.530 32.444

9 1.125 280.800 147.273 104.000 74.286 58.119 49.611 42.221 36.499

10 1.250 312.000 163.636 115.556 82.540 64.577 55.124 46.913 40.555

11 1.375 343.200 180.000 127.111 90.794 71.034 60.636 51.604 44.610

12 1.500 374.400 196.364 138.667 99.048 77.492 66.148 56.295 48.666

13 1.625 405.600 212.727 150.222 107.302 83.950 71.661 60.986 52.721

14 1.750 436.800 229.091 161.778 115.556 90.407 77.173 65.678 56.776

15 1.875 468.000 245.455 173.333 123.810 96.865 82.686 70.369 60.832

16 2.000 499.200 261.818 184.889 132.063 103.323 88.198 75.060 64.887

17 2.125 530.400 278.182 196.444 140.317 109.780 93.710 79.751 68.943

18 2.250 561.600 294.545 208.000 148.571 116.238 99.223 84.443 72.998

19 2.375 592.800 310.909 219.556 156.825 122.696 104.735 89.134 77.054

20 2.500 624.000 327.273 231.111 165.079 129.153 110.247 93.825 81.109

21 2.625 655.200 343.636 242.667 173.333 135.611 115.760 98.516 85.165

22 2.750 686.400 360.000 254.222 181.587 142.069 121.272 103.208 89.220

23 2.875 717.600 376.364 265.778 189.841 148.526 126.784 107.899 93.276

Notes: Objective: Determine a length of wire for a End-Fed antenna suitable for the 40, 30, 20, & 15m bands such that the impedance at the end will be low and therefore more easily matched. This is based on the work by G3CCB published in "The Antenna File". Mr. Chester rationalized that the safe working lengths were between 1/8 - 3/8, and 5/8 - 7/8 wave long, steering clear of the high impedance half wave point. Recommended lengths from the Chester article: 26.5m/86.9ft for 160M - 10M 15m/49.2ft for 80, 40, 20, 17, 15, 12, 10M 10m/32.8ft for 80, 40, 30, 17, 15, 12, 10M

Red

1/2 wavelength "stay away" lengths