Tuning angle of groundplane antenna.
"Roy Lewallen" wrote in message
...
Scott wrote:
I've always drooped my (VHF and UHF) radials at 45 degrees and they have
always worked OK.
A droop of 45 degrees brings the impedance at resonance very close to 50
ohms. EZNEC example file VHFGP.EZ has 45 degree drooping radials. At
resonance (around 142.2 MHz), the input resistance is about 51.4 ohms.
Roy Lewallen, W7EL
I heard once it is the sin of the angle times the impedance of a dipole.
Not sure if it is correct but it works for 50 ohms OK. Also heard that if
divide the sine of the angle inot the impedance of a 1/4wl antenna with
ground plane at right angles to the antenna it also works. Again maybe just
for 50 ohms. Might be fun to check out with EZNEC.
Jimmie
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