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Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Ma
gn
eti
c
Lo
op
Co
ok
bo
ok
G. H
ero
n,
N2A
PB
&
J. E
verh
art
, N
2C
X
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Ov
erv
iew
Fa
scin
ation
with
ST
Ls:
“Sm
all
Tra
nsm
itting
Ante
nn
as”
• d
ire
ctivity,
se
lectivity,
no
ise
re
du
ctio
n
Com
mo
n lim
ita
tion
s t
od
ay:
• su
rfa
ce
are
a, n
arr
ow
BW
• tu
nin
g, m
ate
ria
ls &
co
nstr
uctio
n, e
ffic
ien
cy
Th
is p
rese
nta
tion
…
• Is
no
t a
tu
tori
al o
n “
co
nve
ntio
na
l” S
TL d
esig
n
• W
e w
ill im
media
tely
focus o
n p
roble
ms o
f curr
ent desig
ns
• A
nd
pre
se
nt e
xp
erim
en
tal m
eth
od
s fo
r
im
pro
vin
g s
tate
-of-
the
-art
ST
L a
nte
nn
as
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Ra
dia
tio
n P
att
ern
It’s
lik
e a
do
ug
hn
ut
…
• V
ert
ica
lly o
rie
nte
d lo
op
giv
es r
ad
iatio
n a
t a
ll ve
rtic
al a
ng
les, a
figure
-8 p
attern
when v
iew
ed fro
m a
bove inclu
din
g N
VIS
thro
ugh
Lo
w a
ng
le r
ad
iatio
n.
• B
est fo
r lo
w e
nd
of H
F e
ve
n w
he
n o
nly
se
ve
ral fe
et a
bo
ve
gro
un
d
• W
he
n o
rie
nte
d h
ori
zo
nta
lly it ra
dia
tes in
a c
ircle
at a
ll a
zim
uth
an
gle
s w
ith
a n
ull
at h
igh
ve
rtic
al a
ng
les.
• B
est a
t th
e u
pp
er
en
d o
f th
e H
F r
an
ge
BU
T m
ust b
e m
ou
nte
d
hig
he
r th
an
a h
alf w
ave
len
gth
ab
ove
gro
un
d.
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Sm
all
Lo
op
Ba
sic
s
Th
ey lo
ok e
lectr
ically
lik
e a
tu
ne
d c
ircu
it w
he
re t
he
ind
ucto
r
is a
la
rge
loo
p w
ith
a c
ircu
mfe
ren
ce
of
ab
out
1/1
0
wave
len
gth
• 4
0m
~ 4
.5' d
ia.
• 2
0m
~ 2
.2' d
ia.
• 1
0m
~ 1
.1' d
ia.
• B
ut u
p to
¼ w
ave
is u
sa
ble
• T
un
ed
by a
ca
pa
cito
r a
t th
e lo
op
en
ds
• V
ari
ab
le c
ap
use
d fo
r tu
na
bili
ty
• M
atc
hin
g m
ea
ns n
ee
de
d fo
r 5
0 o
hm
fe
ed
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Sm
all
Lo
op
Eq
uiv
ale
nt
Cir
cu
it
Mat
ch
RR
AD
RL
OS
S
L
C
Copper
Loop
3 F
t D
ia.
1/2
in.
tub
ing
L =
2.5
uH
C =
52
pf
RR
AD
=
.0
65
Ω
RLO
SS =
.0
7Ω
Q =
810
BW
= 1
7 k
Hz
VC
AP =
94
3v @
5W
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Sm
all
Lo
op
De
sig
n E
qu
ati
on
s
• R
ad
iati
on
Resis
tan
ce -
oh
ms
RR
= 3
.38
x 1
0-8
x (
F2 x
A)
2 !!
!!!!
!!!!
!!!!
• L
oss R
esis
tan
ce -
oh
ms
RL
= 9
.96
x 1
0-4
x s
qrt
(F)
x S
/ D
• E
ffic
ien
cy -
%
Eff
= R
R x
10
0 /
(R
R +
RL
)
• I
nd
ucta
nce -
uH
L =
1.9
x 1
0-8
x S
x (
1.2
e-.1
36
S +
.8
1)
x (
7.3
53
x l
og
10
(9
6 x
S/(Π
x D
) –
6.3
86
0)
• Q
(lo
ad
ed
)
QL =
2 x
Π x
F /
(2 x
(R
R +
RL)
)
• B
an
dw
idth
- k
Hz
BW
= F
/ Q
L
F =
Fre
q (
MH
z), A
= L
oo
p A
rea
(ft)
, D
= C
on
d. D
ia.
(in),
Fo
r a c
ircu
lar
loo
p w
ith
a t
ub
ula
r co
pp
er
co
nd
ucto
r in
fre
e s
pace …
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
aa5
tb_lo
op
_v
1.2
2a
.xls
Ca
lcu
lato
r
Au
tom
ate
s l
oo
p d
esig
n a
nd
“w
hat-
ifs”
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Min
imiz
ing
Co
nd
uc
tor
Lo
ss
Lo
ss E
ffic
ien
cy a
nd B
an
dw
idth
vs T
ub
ing
siz
e
** 3
” A
l co
nd
ucto
r o
nly
1 d
B loss
M
idnig
ht
Loop d
esig
n g
oal
C
opper
A
lum
inum
Dia
- in
R
r -
mΩ
R
L -
mΩ
E
ff -
%
L -
uH
B
W -
kH
z
R
r -
mΩ
R
L -
mΩ
E
ff -
%
L -
uH
B
W -
kH
z
0.5
64.9
71.2
48
2.5
17.3
64.9
112
36.6
2.5
22.6
1
64.9
35.1
64.9
2.1
15.2
64.9
56.1
53.6
2.1
18.4
2
64.9
17.6
78.7
1.7
15.5
64.9
28.1
69.8
1.7
17.4
3
64.9
11.7
84.7
1.5
16.6
64.9
18.7
81 *
* 1.5
17.4
4
64.9
8.8
88.1
1.3
18
64.9
14.1
82.2
1.3
19.3
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Oth
er
Lo
ss F
acto
rs
Con
nectio
ns n
eed
ca
refu
l a
tte
ntion
• A
ny m
ech
an
ica
l co
nn
ectio
n is lo
ssy
• J
oin
ts n
ee
d to
be
so
lde
red
or
we
lde
d
Th
e t
un
ing
ca
pacito
r is
critica
l
• R
ota
ry tu
nin
g c
ap
ne
ed
s b
est in
su
latio
n
• C
era
mic
vs p
henolic
• L
ow
est lo
ss d
iele
ctr
ic if u
se
d
• R
ota
ry jo
ints
ge
ne
rally
ba
d
• M
easure
d s
evera
l m
Ω t
o 2
0 m
Ω
• C
hanges e
ach t
ime r
etu
ned
• U
su
al ch
oic
es a
re tro
mb
on
e, sp
lit s
tato
r o
r va
cu
um
va
ria
ble
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Eff
icie
ncy C
on
tro
vers
y
Pro
f M
ike
Un
de
rhil
l G
3L
HZ
ha
s c
ha
llen
ged
esta
blis
he
d
loop d
esig
n t
heory
cla
imin
g v
ery
sm
all
loop e
ffic
iency is
actu
ally
ma
ny d
B g
rea
ter
tha
n c
laim
ed
(R
ef
8).
Note
d a
nte
nn
a e
xp
ert
Jo
hn
Be
lro
se
VE
2C
V h
as
counte
red w
ith N
EC
ante
nna m
odelin
g a
nd r
eal-
world
me
asu
rem
en
ts u
pho
ldin
g t
he
esta
blis
he
d m
ea
ns o
f
de
rivin
g s
ma
ll lo
op
effic
ien
cy.
H
e c
on
clu
des t
ha
t G
3L
HZ
use
d f
law
ed
exp
erim
en
tal d
ata
an
d r
ea
so
nin
g t
o u
ph
old
his
unort
hodox v
iew
s (
Ref 9,1
0).
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Mid
nig
ht
Lo
op
Lo
ss A
pp
roa
ch
Use a
larg
e f
lat
con
ducto
r
• A
lum
inu
m fla
sh
ing
• E
stim
ate
d lo
ss s
imila
r to
3”
tub
ing
• R
ef 7
giv
es ju
stifica
tio
n fo
r fla
t co
nd
ucto
r
Ends o
f lo
op a
re o
verlapped t
o m
ake c
apacitor
• C
om
ple
tely
jo
intle
ss c
on
str
uctio
n
• T
un
ed
by v
ary
ing
pla
te s
pa
cin
g
• A
ir d
iele
ctr
ic fo
r sm
all
C
• L
ow
loss T
eflon for
hig
her
C
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Mid
nig
ht
Lo
op
as
Eq
uiv
to
3 i
n d
ia.
Tu
bin
g
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Op
tim
um
Tu
nin
g M
eth
od
Hig
h Q
ma
ke
s t
un
ing
difficu
lt
• M
an
ua
l tu
nin
g to
uch
y
• H
an
d p
roxim
ity c
au
se
s d
etu
nin
g
Ob
vio
us s
olu
tio
n is t
o m
oto
rize
But tu
nin
g c
an s
till
be t
ouchy
• H
igh
ge
ar
ratio
ne
ed
ed
• T
un
ing
to
pe
ak n
ois
e ta
ke
s s
kill
• W
atc
hin
g S
WR
me
ter
eve
n w
ors
e
Mid
nig
ht
loo
p t
arg
et
ap
pro
ach
is a
use
r-fr
ien
dly
vis
ua
l d
ispla
y
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Th
e M
idn
igh
t L
oo
p
An E
xperim
enta
l, H
igh-e
ffic
iency,
Gra
phic
-Tunable
Magnetic L
oop
PIC
Att
en
Spot
Tra
nsceiv
er
Sp
ectr
og
rap
h
NU
E-P
SK
(or
PC
w/R
ocky)
Lo
op
Co
ntr
oller
RF
Sam
ple
r
Head
Tu
nin
g
Cap
RF
Feed
po
int
RF
Sam
plin
g
An
ten
na
(PA
C-1
2)
Inte
gra
ted in
Loop(?
)
Op
era
tin
g P
rin
cp
les
1)
While
in
Rx m
ode,
vie
w s
pectr
um
on s
pectr
ogra
phic
dis
pla
y, as d
eliv
ere
d f
rom
RF
Sam
ple
r S
DR
2)
Fin
d s
ignals
of
inte
rest
(or
quie
t are
a)
by m
ovin
g c
urs
or
alo
ng s
pectr
ogra
ph
3)
Pre
ss “
Spot”
on C
ontr
ol U
nit to k
ey X
cvr.
P
IC p
laces A
TT
EN
in
lin
e t
o d
eliv
er
QR
ppp
sig
nal to
Loop ,
whic
h is d
ete
cte
d b
y R
F S
am
ple
r S
DR
and d
eliv
ere
d b
ack t
o s
pectr
ogra
phic
dis
pla
y
to s
how
curr
ent
opera
tin
g f
requency o
f th
e L
oop
4)
PIC
drives L
oop c
apacitor
to r
e-t
une L
oop r
esonance t
o d
esired c
urs
or
location (
frequency).
5)
PIC
sw
itches A
ttenuato
r out
of
circuit, re
moves p
ow
er
from
Sam
plin
g S
DR
, drives T
ransceiv
er
to t
he
frequency o
f th
e c
urs
or
in t
he s
pectr
ogra
hic
dis
pla
y,
and u
ser
begin
s o
pera
tin
g p
er
norm
al.
PV
C
Su
pp
ort
Fra
mew
ork
10”-w
ide
Alu
min
um
Fla
sh
ing
So
ftro
ck
+ S
DR
(R
eceiv
e-o
nly
)
Up /
Dow
n
Drive
RF
Locate
CA
T
RF
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Lo
op
Co
ntr
oller
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Lo
op
Co
ntr
oller
M
idn
igh
t L
oo
p C
on
tro
lle
r c
on
sis
ts o
f …
1)
Se
lft-
co
nta
ine
d b
att
ery
fo
r p
ow
eri
ng
Lo
op
ca
pac
ito
r tu
nin
g m
oto
r;
2)
“U
p/D
ow
n” S
wit
ch
(re
d)
for
ma
nu
all
y t
un
ing
Lo
op
;
3)
Rela
y s
wit
ch
ing
in
/ou
t 7
0W
du
mm
y l
oa
d a
nd
N7V
E S
WR
In
dic
ati
on
cir
cu
it
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
SD
R S
pectr
um
Tu
nin
g U
nit
So
ftR
ock
Receiv
er
(20m
)
+12V
PA
C-1
2
Sam
plin
g
An
ten
na
I Q
eZ
DS
P
(Dem
odula
tor)
+5V
US
B A
ud
io
to N
UE
-PS
K M
od
em
for
sp
ectr
um
dis
pla
y
of
ban
d a
cti
vit
y
Si5
70
Clo
ck G
en
era
tor
& D
isp
lay
+12V
Ro
tary
En
co
der 4x R
eceiv
er
Fre
qu
en
cy
(~56 M
Hz)
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
SD
R S
pectr
um
Tu
nin
g U
nit
NU
E-P
SK
Dig
ital
Mo
de
m (
up
per
left
)
Sp
ectr
um
dis
pla
y o
f S
DR
ou
tpu
t u
se
d to
dis
pla
y b
an
d a
ctivity o
uts
ide
th
e n
arr
ow
ba
nd
wid
th o
ffe
red b
y t
he
mid
nig
ht L
oo
p.
SD
R T
un
ing
Co
ntr
olle
r (l
ow
er
rig
ht)
So
ftR
ock v
5.0
(le
ft)
so
ftw
are
de
fined r
eceiv
er,
eZ
DS
P s
tart
er
kit r
un
nin
g N
UE
-SD
R v
0.5
so
ftw
are
an
d
Si5
70
Con
trolle
r &
Fre
qu
en
cy G
en
era
tor
on
fro
nt p
an
el
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Th
e S
tati
on
Clo
ckw
ise …
Yae
su
’s F
T-8
17 Q
RP
tra
nsc
eiv
er
NU
E-P
SK
Dig
ital
Mo
de
m (
for
sp
ec
tru
m d
isp
lay)
Mid
nig
ht
Lo
op
Sp
ec
tru
m T
un
ing
Co
ntr
olle
r
Mid
nig
ht
Lo
op
Co
ntr
olle
r
Rea
r vie
w o
f s
tati
on
sh
ow
ing
ca
ble
in
terc
on
nec
ts
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
In O
pera
tio
n
Mid
nig
ht
Lo
op
sta
nd
ing
ato
p t
hre
e-f
oo
t s
no
w in
Ma
ryla
nd
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
In O
pera
tio
n
N2A
PB
at
the
op
era
tin
g p
osit
ion
of
the M
idn
igh
t L
oo
p s
tati
on
in
sn
ow
bo
un
d M
ary
lan
d.
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Co
mp
ara
tive F
ield
Testi
ng
T
esting u
nder
care
fully
contr
olle
d c
onditio
ns to c
om
pa
re the M
idnig
ht Loop to the M
FJ L
oop
Need
fla
t are
a f
ree o
f tr
ees, au
tos, fe
nces, p
eo
ple
, p
ole
s, etc
. at
least
300 f
eet
lon
g a
nd
200 f
eet
wid
e. P
refe
rab
ly, cle
ar
are
a s
ho
uld
be
mo
re t
han
tw
ice t
hese d
imen
sio
ns w
ith
no
thin
g h
igh
er
than
a c
ou
ple
of
feet
to a
vo
id u
nw
an
ted
refl
ecti
on
s o
r ab
so
rpti
on
of
RF
en
erg
y.
In a
dd
itio
n t
here
can
be n
o t
ran
sm
itte
rs, la
rge e
lectr
ic m
oto
rs, p
ow
er
su
bsta
tio
ns, p
ow
er
lin
es, o
r o
ther
RF
in
terf
ere
nce s
ou
rces w
ith
in 1
/4
mile.
Th
is t
esti
ng
in
vo
lves s
ett
ing
up
a f
lat
measu
rem
en
t are
a w
ith
no
ob
str
ucti
on
s s
uch
as t
rees, h
ou
ses, h
ills
, cars
, etc
to
do
th
e
test.
Th
e a
nte
nn
a u
nd
er
test
is s
et
at
a m
easu
red
dis
tan
ce, say 1
00
feet
fro
m a
3 f
t w
hip
ov
er
a 3
ft
gro
un
d p
late
. It
is o
rien
ted
vert
ically.
Th
e t
est
an
ten
na h
as its
base a
t ab
ou
t 3 f
t ab
ov
e g
rou
nd
wh
ile
the 1
mete
r w
hip
is a
bo
ut
4-1
/2 f
eet
ab
ov
e g
rou
nd
.
A t
ran
sm
itte
r is
co
nn
ecte
d t
o t
he a
nte
nn
a u
nd
er
test
an
d its
ou
tpu
t care
fully m
easu
red
. T
he 3
fo
ot
wh
ip is c
on
necte
d t
o a
test
receiv
er.
T
he latt
er
has t
o b
e c
ap
ab
le o
f m
easu
rin
g lo
w
sig
nal le
vels
to
wit
hin
0.5
dB
or
so
rep
eata
bly
. E
ith
er
a
sp
ectr
um
an
aly
zer
or
calib
rate
d t
est
receiv
er
is b
est.
It
may b
e
po
ssib
le t
o u
se t
he H
ayw
ard
mic
row
att
mete
r w
ith
a s
harp
ban
dp
ass f
ilte
r.
Fir
st
the M
FJ lo
op
is s
et
up
as t
he t
est
an
ten
na a
nd
th
e
tran
sm
itte
r is
en
ab
led
. T
he s
ign
al at
the 3
ft
wh
ip is m
easu
red
as t
he M
FJ lo
op
is r
ota
ted
. R
eceiv
ed
sig
nal m
easu
rem
en
ts a
re
mad
e a
90 d
eg
ree in
cre
men
ts. Id
eally 0
deg
rees w
ill b
e w
ith
the lo
op
axis
po
inte
d in
th
e d
irecti
on
of
the w
hip
.
Next
the M
idn
igh
t L
oo
p is s
et
up
as t
he a
nte
nn
a u
nd
er
test
an
d
the a
bo
ve s
eq
uen
ce o
f m
easu
rem
en
ts is r
ep
eate
d.
Fin
ally t
he M
FJ lo
op
is u
sed
fo
r a s
eco
nd
set
up
measu
rem
en
ts t
o a
ssu
re r
ep
eata
bilit
y.
All m
easu
rem
en
ts s
ho
uld
be p
erf
orm
ed
wit
hin
a c
ou
ple
ho
ur
peri
od
wit
h w
eath
er,
tem
pera
ture
, etc
. re
main
ing
rela
tiv
ely
co
nsta
nt.
To
p V
iew
:
Sid
e V
iew
:
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Co
mp
ara
tive F
ield
Testi
ng
T
he P
hysic
al S
etu
p
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Co
mp
ara
tive F
ield
Testi
ng
R
es
ult
s &
Ob
se
rva
tio
ns
Mar
8, 2010
Fo
rest
Hill, M
D
Tim
e
Fre
q
(MH
z)
SW
R
Xm
it P
wr
(Watt
s)
Batt
ery
(Vo
lts)
Rx N
ois
e
(dB
m)
Rx S
ign
al
(dB
m)
2:4
4 P
M14.0
80
1.9
0.4
12.4
-67
-24.6
2:5
7 P
M14.0
96
1.9
0.4
-64
-42.1
3:0
2 P
M14.0
96
1.9
0.4
-64
-24.6
3:2
5 P
M14.0
21.5
.3/.4
-59
-24
3:3
8 A
M14.0
46
1.5
.3/.4
12V
-60
-43
3:4
5 P
M14.1
1.8
0.4
11.5
V-6
8-2
3.1
A
ppare
nt lo
wer
transm
it p
ow
er
mig
ht yi
eld
even h
igher
eff
icie
ncy f
or
Mid
nig
ht Loop.
4. S
tronger
receiv
ed s
ignal fr
om
Mid
nig
ht Loop s
uggests
hig
her
eff
icie
ncy than the
M
FJ loop, on the o
rder
of
1 d
B.
5. M
idnig
ht Loop a
lso s
how
s d
eep n
ull
when b
roadsid
e, su
ggesting low
feedlin
e r
adia
tion.
6. T
ransm
it p
ow
er
cannot be a
ccura
tely
accounte
d f
or
sin
ce m
easure
ment re
solu
tion w
as 0
.1 W
.
No
tes:
1. A
ppro
x 4
0 d
b S
/N r
atio a
t re
ceiv
e e
nd m
eans test data
not conta
min
ate
d b
y n
ois
e
2. 17 d
B n
ull
with M
FJ loop 9
0 d
eg. tr
ansm
issio
n p
ath
indic
ate
s little o
r no loop f
eedlin
e r
adia
tion.
3. Id
entical re
ceiv
ed s
ignals
when M
FJ loop turn
ed 1
80 d
eg. S
how
s g
ood p
attern
sym
metr
y.
Test
3:
MF
J L
oop r
ota
ted 1
80 d
eg. C
W
Test
4:
Mid
nig
ht Loop o
riente
d tow
ard
receiv
e a
nte
nna
Test
5:
Mid
nig
ht Loop r
ota
ted 9
0 d
eg. C
W
Test
6:
Mid
nig
ht Loop r
ota
ted 1
80 d
eg. C
W
Co
mp
ara
tiv
e L
oo
p A
nte
nn
a T
ests
Weath
er:
cle
ar,
about 50-d
egF
sunny w
ith a
lig
ht w
ind
Test
1:
MF
J L
oop o
riente
d tow
ard
receiv
e a
nte
nna
Test
2:
MF
J L
oop r
ota
ted 9
0 d
eg. C
W
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Perf
orm
an
ce
MF
J L
oo
p …
. B
W ~
30
kH
z
MF
J L
oo
p
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Perf
orm
an
ce
Mid
nig
ht
Lo
op
…. B
W ~
50
kH
z
Mid
nig
ht
Lo
op (
gro
un
d-m
ou
nte
d)
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Perf
orm
an
ce
Mid
nig
ht
Lo
op
…. B
W ~
20
kH
z
Mid
nig
ht
Lo
op (
mo
un
ted
at
30
fee
t)
10 k
Hz s
can
ste
p s
ize
skip
ped
ov
er
reso
nan
ce f
req
uen
cy
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Perf
orm
an
ce
Mid
nig
ht
Lo
op
…. B
W ~
40
kH
z
Mid
nig
ht
Lo
op (
mo
un
ted
at
30
fee
t)
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Perf
orm
an
ce
Mid
nig
ht
Lo
op
…. B
W ~
20
kH
z
Mid
nig
ht
Lo
op (
mo
un
ted
at
30
fee
t)
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Perf
orm
an
ce
Mid
nig
ht
Lo
op
…. B
W ~
30
kH
z
Mid
nig
ht
Lo
op (
mo
un
ted
at
30
fee
t)
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
De
mo
Liv
e D
em
o
an
d/o
r
Vid
eo
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Next
Ste
ps
• M
ore
fie
ld m
easure
ments
• E
mp
iric
ally
de
term
ine
RLO
SS
• T
ry c
op
pe
r in
ste
ad
of
alu
min
um
• In
tegra
te s
am
plin
g a
nte
nna
• In
teg
rate
con
tro
ller
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Ap
pen
dix
• B
ackg
rou
nd
Lite
ratu
re
• R
efe
ren
ce
s
• C
on
str
uctio
n D
eta
ils
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Lo
op
An
aly
sis
Calc
ula
tors
1)
aa
5tb
_lo
op
_v1
.22
a.x
ls c
alc
ula
tor
Go
od
ov
eral
l ca
lcu
lato
r.
Do
es n
ot
acco
un
t fo
r gro
un
d l
oss
, h
and
les
on
ly r
ou
nd l
oo
ps –
wo
rks
wit
h O
pen
Off
ice
as w
ell
as
MS
Ex
cel.
htt
p:/
/ww
w.a
a5tb
.co
m/a
a5tb
_lo
op
_v
1.2
2a.
xls
2)
KI6
GD
calc
ula
tor
Mo
re g
ener
al t
han
th
e A
A5
TB
cal
cula
tor.
htt
p:/
/ww
w.m
agn
etic
loo
pan
ten
na.
com
/lo
op
calc
.zip
3)
G4
FG
Q C
alc
ula
tors
Nu
mer
ou
s D
OS
cal
cula
tor
pro
gra
ms
incl
ud
ing s
ever
al f
or
smal
l lo
op
s. H
and
les
man
y m
ore
par
amet
ers
than
ab
ov
e
calc
ula
tors
, th
ou
gh
we
hav
e n
ot
ver
ifie
d a
ccu
racy
. h
ttp
://w
ww
.zer
ob
eat.
net
/G4
FG
Q/p
age3
.htm
l
Re
fere
nc
es
(1
of 5
)
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Re
fere
nc
es
(2
of 5
)
Sele
cte
d S
mall T
ran
sm
itti
ng
Lo
op
s i
n r
ad
io a
mate
ur
pu
blicati
on
s:
1)
Th
e A
rmy
Lo
op
in
Ha
m C
om
mu
nic
ati
on
, L
. M
cCo
y W
1IC
P,
QS
T M
ar
19
68
pp
17
-18
, 1
50
Lo
op
an
ten
nas
des
ign
ed f
or
NV
IS (
Nea
r V
erti
cal
Inci
den
ce S
ign
alin
g)
bu
ilt
by t
he
US
Arm
y f
or
use
in
Vie
tnam
. N
VIS
ch
arac
teri
stic
pro
vid
ed n
eed
ed c
lose
-in
co
mm
un
icat
ion
s at
th
e lo
w e
nd
of
the
HF
ban
d a
nd
av
oid
ed h
igh
sig
nal
lo
ss f
rom
ju
ngle
fo
liag
e.
AR
RL
staf
fer
du
pli
cati
on r
esult
ed i
n a
n a
dm
itte
dly
loss
y a
nte
nna
that
was
sti
ll q
uit
e usa
ble
.
2)
Sm
all
Hig
h-E
ffic
ien
cy L
oo
p A
nte
nn
as,
Ted
Ha
rt W
5Q
JR
, Q
ST
J
an
19
86
Har
t d
ocu
men
ted
th
e d
esig
n o
f m
agn
etic
lo
op
s w
ith
a s
et o
f su
ccin
ct e
qu
atio
ns
in t
his
pie
ce.
It
sh
ow
ed h
ow
su
cces
sfu
l lo
op
s co
uld
be
bu
ilt
wit
h p
red
icta
ble
, re
pea
tab
le p
erfo
rman
ce.
Mat
eria
l fr
om
th
is a
rtic
le a
lso
ap
pea
rs i
n r
ecen
t A
RR
L R
ad
io A
ma
teu
r H
an
db
oo
ks a
nd
AR
RL
An
ten
na
Bo
oks
.
3)
Lo
op
Bo
ok
, T
ed H
art
W5
QJ
R A
nte
nn
ex –
ww
w.a
nte
nn
ex.c
om
\ A
va
ila
ble
by
pu
rch
ase
on
ly
An
ex
pan
ded
tre
atm
ent
of
smal
l lo
op
an
d r
elat
ed a
nte
nn
as w
ell
wo
rth
pu
rch
asin
g b
y s
erio
us
loo
p e
xp
erim
ente
rs.
4)
Tra
nsm
itti
ng S
hort
Loop A
nte
nn
as
for
the
HF
Ban
ds,
Rob
erto
Cra
igh
ero I
1A
RZ
, C
om
mu
nic
ati
on
s Q
ua
rter
ly 1
99
3
Su
mm
er/A
utu
mn
A t
ho
rou
gh
des
crip
tio
n o
f h
ow
to
mak
e a
ver
y e
ffic
ien
t, r
emo
tely
tu
nab
le s
mal
l tr
ansm
itti
ng l
oo
p.
5)
An
Up
da
te o
n C
om
pa
ct T
ran
smit
tin
g L
oo
ps,
J.
S. B
elro
se V
E2
CV
, Q
ST
No
v 1
99
3,
pp
37
-40
Go
od
tre
atm
ent
of
loo
p a
nte
nn
as a
nd
th
eir
char
acte
rist
ics
wit
h N
EC
mo
del
ing d
ata
and
mea
sure
men
ts t
o e
val
uat
e p
erfo
rman
ce.
Bel
rose
is
an e
min
entl
y q
ual
ifie
d y
et p
ract
ical
an
ten
na
exp
ert
wh
o h
as w
ritt
en m
any c
lass
ic a
nte
nn
a ar
ticl
es i
n r
adio
am
ateu
r li
tera
ture
.
6)
Per
form
an
ce o
f E
lect
rica
lly
Sm
all
Tra
nsm
itti
ng
Lo
op
An
ten
na
s, J
. S
. B
elro
se V
E2
CV
, P
art
I, R
ad
Co
m,
pp
. 6
4-6
7,
Pa
rt I
I,
Ra
dC
om
, p
p. 88-9
8, Ju
ne/
Ju
ly 2
004
Up
dat
ed a
nd
ex
pan
ded
sm
all
tran
smit
tin
g l
oo
p d
ata
wit
h a
dd
itio
nal
NE
C m
od
elin
g a
nd
su
pp
ort
ing a
nte
nn
a ra
nge
mea
sure
men
t d
ata.
7)
Res
ista
nce
of
Fo
il C
on
du
cto
rs F
or
An
ten
na
s, R
ud
y S
ever
ns
N6
LF
, Q
EX
Ma
y/J
un
e 2
00
2 T
ech
No
tes
Just
ific
atio
n f
or
the
use
of
wid
e, t
hin
fo
ils
as l
ow
lo
ss c
on
du
cto
rs f
or
ante
nn
as.
Res
ult
s o
f co
mp
ute
r m
od
elin
g s
ho
w t
hat
“cu
rren
t
cro
wd
ing”
at t
he
edge
of
wid
e co
nd
uct
ors
off
ers
sign
ific
antl
y l
ess
loss
th
an h
as b
een
po
pu
larl
y t
ho
ugh
t.
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Sm
all L
oo
p A
nte
nn
a C
on
tro
vers
y
8)
Th
e T
ruth
abou
t L
oops,
Mik
e U
nd
erH
ill,
G3L
HZ
, R
SG
B I
nte
rnati
on
al A
nte
nn
a C
oll
ecti
on
, 2
00
3
In t
his
pap
er a
nd
sev
eral
oth
ers
Mik
e U
nd
erh
ill
and
Ele
ctri
cal
En
gin
eeri
ng p
rofe
sso
r cl
aim
ed t
hat
cu
rren
t th
eory
an
d d
escr
ipti
on
s o
f
the
effi
cien
cy a
nd
rad
iati
ng e
ffec
tiv
enes
s is
fla
wed
. H
e cl
aim
s th
at c
rite
ria
use
d t
o e
val
uat
e th
is t
yp
e o
f an
ten
na
is i
nco
rrec
t an
d c
an
lead
to
dis
crep
anci
es i
n e
ffic
ien
cy o
f u
p t
o 3
0 d
B.
9)
Tru
th a
nd
Un
tru
th, J
. S
. B
elro
se V
E2
CV
, P
rese
nte
d a
t th
e Q
CW
A 2
00
4 I
nte
rnat
ion
al C
on
ven
tio
n, A
mat
eur
Rad
io T
ech
nic
al
Ses
sio
n, F
rid
ay,
Oct
ob
er 1
5,
hel
d a
t th
e L
ord
Elg
in H
ote
l, O
ttaw
a, O
N C
anad
a –
av
aila
ble
at
htt
p:/
/qcw
a70
.org
/tru
th a
nd
un
tru
th.p
df
10
) C
om
pact
Loops
Re-
visi
ted,
J.
S.
Bel
rose
VE
2C
V, A
nte
nn
ex O
nli
ne
Magazi
ne,
Ma
r 2
00
1 i
ssu
e (1
3-p
ag
e a
rtic
le)
av
ail
ab
le b
y
pa
id s
ub
scri
pti
on
on
ly
No
ted
ex
per
t Ja
ck B
elro
se r
efu
tes
the
clai
ms
of
Mik
e U
nd
erh
ill
abo
ut
per
form
ance
of
smal
l lo
op
an
ten
nas
an
d p
rese
nts
cre
dib
le
mo
del
ing a
nd
tes
t d
ata
to u
ph
old
th
e tr
adit
ion
al m
eth
od
s fo
r ef
fici
ency
an
d e
ffec
tiv
enes
s ca
lcu
lati
on
s in
Ref
s 9
an
d 1
0.
Re
fere
nc
es
(3
of 5
)
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
Co
ntr
ol, S
oft
ware
an
d E
lec
tro
nic
s
1)
An
SW
R N
ull
Met
er,
Pa
ul
Ch
rist
ense
n, W
9A
C, Q
ST
Feb
rua
ry 2
01
0,
pp
30
-32
.
Des
crib
es a
co
nv
enie
nt
tech
niq
ue
for
on
-th
e-ai
r tu
nin
g t
hat
pro
vid
es o
nly
ver
y l
ow
tra
nsm
itte
d p
ow
er l
evel
s. T
his
ap
pro
ach
was
uti
lize
d i
n t
he
Mid
nig
ht
Lo
op
Co
ntr
oll
er.
2)
N7
VE
LE
D S
WR
In
dic
ato
r
Dan
Tay
loe,
N7
VE
des
ign
ed a
sim
ple
an
d c
on
ven
ien
t ab
sorp
tiv
e S
WR
in
dic
atin
g c
ircu
it s
om
e yea
rs a
go
, u
sed
in
th
e N
orC
al B
LT
tun
er k
it (
htt
p:/
/ww
w.n
orc
alq
rp.o
rg/n
orc
al_
blt
.htm
), a
nd
oth
er p
lace
s.
We
use
d t
his
cir
cuit
in
th
e M
idn
igh
t L
oo
p C
on
tro
ller
.
3)
So
ftR
ock
SD
R, T
on
y P
ark
s K
B9
YIG
As
a b
asis
fo
r th
e M
idn
igh
t L
oo
p’s
“so
ftw
are
def
ined
rad
io s
amp
lin
g h
ead
”, w
e u
sed t
he
po
pu
lar
and
in
exp
ensi
ve
So
ftR
ock
SD
R
circ
uit
s d
esig
ned
an
d p
rod
uce
d b
y T
on
y P
ark
s, K
B9
YIG
. S
ee h
is w
ebsi
te (
htt
p:/
/ww
w.k
b9
yig
.co
m/)
to
vie
w h
is c
om
ple
te l
ine
of
So
ftR
ock
rec
eiv
ers,
tra
nsm
itte
rs,
tran
scei
ver
s an
d a
cces
sori
es.
4)
NU
E-S
DR
So
ftw
are
ver
sio
n 0
.5,
M.C
ram
W8
NU
E
Th
e gen
esis
of
the
stan
dal
on
e D
SP
so
ftw
are
call
ed “
NU
E-S
DR
”, d
evel
op
ed b
y M
ilt
Cra
m, W
8N
UE
, w
ritt
en f
or
the
Tex
as
Inst
rum
ents
“eZ
DS
P S
tick
” p
latf
orm
(h
ttp
://f
ocu
s.ti
.co
m/d
ocs
/to
ols
w/f
old
ers/
pri
nt/
tmd
sezd
28
12
.htm
l)
5)
NU
E-P
SK
Dig
ita
l M
od
em, M
.Cra
m W
8N
UE
an
d G
.Her
on
N2
AP
B
Th
e sp
ectr
um
dis
pla
y o
f th
e N
UE
-PS
K m
od
em w
as e
ffec
tiv
ely u
sed
in
th
e M
idn
igh
t L
oo
p t
un
ing s
yst
em t
o d
isp
lay b
and
act
ivit
y
ou
tsid
e th
e v
iew
of
the
nar
row
-BW
lo
op
. (h
ttp
://w
ww
.nu
e-p
sk.c
om
/)
6)
Si5
70
Co
ntr
oll
er &
Fre
qu
ency
Gen
era
tor,
Kee
s T
ale
n K
5B
CQ
an
d J
oh
n F
ish
er K
5J
HF
We
use
d t
his
wo
nd
erfu
l an
d i
nex
pen
siv
e fr
equ
ency
gen
erat
or
and
dis
pla
y i
n t
he
Lo
op
’s S
pec
tru
m T
un
ing C
on
tro
ller
SD
R. I
t is
pro
du
ced
by K
5B
CQ
an
d K
5JH
F o
f th
e A
ust
in Q
RP
Clu
b (
htt
p:/
/ww
w.q
sl.n
et/k
5b
cq/k
its/
kit
s.h
tml)
Re
fere
nc
es
(4
of 5
)
Th
e M
idn
igh
t L
oo
p
Th
e M
idn
igh
t L
oo
p
Ma
ss
Co
n 2
01
0
Ma
ss
Co
n 2
01
0
G.
He
ron
N2
AP
B
&
J. E
ve
rhart
, N
2C
X
G.
He
ron
N2
AP
B
&
J.
Ev
erh
art
, N
2C
X
1
) S
teve
Ya
tes
AA
5T
B s
ite
htt
p:/
/ww
w.a
a5
tb.c
om
/lo
op
.htm
l
On
e o
f th
e bes
t over
all
refe
rence
sit
es o
n t
he
Web
\des
crib
ing t
he
theo
ry a
nd p
ract
ice
of
smal
l tr
ansm
itti
ng l
oo
p a
nte
nn
as.
Has
add
itio
nal
lin
ks
to o
ther
sit
es.
2)
KI6
GD
sit
e h
ttp
://w
ww
.ma
gn
etic
loo
pa
nte
nn
a.c
om
/
Yet
an
oth
er g
oo
d s
ite
for
the
seri
ou
s lo
op
fan
. A
lso
has
oth
er l
ink
s.
3)
W2
BR
I si
te h
ttp
://w
ww
.sta
nd
pip
e.co
m/w
2b
ri/
Ex
cell
ent
site
fo
r lo
w H
F b
and
ver
y e
ffic
ien
t tr
ansm
itti
ng l
oo
ps,
in
clu
din
g a
12
’ x
12
’ sq
uar
e lo
op
fo
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Min
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