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Old August 2nd 09, 09:01 PM posted to rec.radio.amateur.antenna
Art Unwin Art Unwin is offline
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First recorded activity by RadioBanter: Mar 2008
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Default Counterpoise for an end-fed wire antenna

On Aug 2, 12:30*pm, "KJ4NTS" wrote:
I'm confused about the requirements for a counterpoise for an end-fed wire antenna. *I understand
that it's needed, but I don't understand what the requirements are.

Can a ground stake at the base of the feed point serve as a counterpoise, or does it need to be
another wire running under the ground below the antenna?

If a wire is required, how long does the counterpoise have to be?

Would it be better to use insulated or uninsulated wire for a buried counterpoise?


With regard to whether you need a counterpoise or not. If your
antenna has two wires at the open end (feed point) then they both must
be connected to the transmitter where there is also an additional
provision for a ground connection ( a must in all cases as the chassis
is floating).If the radiator has only one termination then only one
transmission wire can be connected to it leaving the other wire to be
connected to a ground system which in effect balances your radiator
with a load that does not radiate unless it is the form of a
counterpoise. The effectiveness of your ground system can be measured
by its effectiveness in supplying a resistive feed impedance somewhat
near 30 ohms (above 20 ohms) or so where your transmitter does not
encounter any problems, a counterpoise will present a higher
impedance. An end fed antenna cannot be of a fractional wavelength and
thus the ground field or counterpoise is required to be added to
provide an impedance that can be fed by the transmitter without a
problem so you can enjoy useage of your antenna