The following dimmensions will be found useful in constructing effective
Groundplane antenna's.
Feed the antenna with 50 ohm RG68 coax for best results, and try to get
the feedpoint at least 1/4 wave above ground.
The number of radials is not critical,but I have found 3 to work best
spaced 120 degrees apart.
The basic formula for constructing the antenna is
(468/Freq (Mhz))/2
This gives the answer in Feet
Multiply the decimal part by 12 to give the inches.
The radials are 5% longer and MUST be exactly the same.
BAND RADIATOR RADIAL
40 m (7.05Mhz) 33Ft 2in 34Ft 10in
30m (10.1Mhz) 23Ft 2in 24Ft 3in
20m (14.05Mhz) 16Ft 7in 17Ft 5in
15m (21.05Mhz) 11Ft 1in 11Ft 8in
10m (28.05Mhz) 8Ft 4in 8Ft 9in
Configuration
| Radiator
|
|
|
|
|
O Feedpoint (centre of coax)
x x
x x
x x
x x
x x
x x
x x Radials (Min of 3)
I have used this simple antenna for over 30 years and have always had
excellent results with it on QRP, Worked many VK and ZL on 14,21 Mhz
The radiator is best made out of 1/2in ali tube and the radials made from
14swg wire. dont forget to insulate the radial ends.
I would be interested in comments from anyone who uses this antenna and
the results you have had with it.
73 es 72 to all fellow QRP operators
de John G3PTO
G QRP 595
Frank, G3YCC
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