[Antennas] Re: In L length, again

Mon Nov 28 02:58:50 EST 2005

Asked,
"thanks for the 160 info, making it a 1/4 w will be easier. I am gong
to go about 55 up, and then 85 ft out.
Will this perform as well as a 1/2w inv vee?"
Bob, near West branch
Bob,
It depends on if your goal is to obtain a high or low angle radiation
launch. Most of us want low angle, unless our primary intent is to maybe
work locals in a net, etc.
A 1/2 wave INV VEE is about 90% efficient. The 1/4 wave INV L efficiency
is entirely dependent upon its ground system. Example: feed point Z on
the L is about 12 ohms. If your ground system (radials) also has an
effective resistance of 12 ohms (30 - 1/4 wave radials on the ground)
then the over all system efficiency is 50%. But the angle of radiation
is much lower @ about 30 degrees. Sobering thought...an INV VEE on 160M
up 30 feet, scaled to a 10M INV VEE of same equivalent wavelength
proportions would be only 2 feet high!!
73, Roy K6XK Iowa