Dave's observation is about how the antenna actually works, as
determined by Mother Nature, and, depending how the antenna is rigged,
he's probably right. Antennas work by carrying RF current, any end fed
radiator needs a counterpoise, which, because it's carrying the same RF
current as the end fed radiator, CAN ALSO RADIATE. Indeed, this antenna,
depending on how it's deployed, can be thought of as an off-center fed
dipole.
Back when I lived in Chicago, I had another "ad hoc" antenna that was
effective on 80 and 160M. My shack was on the second floor, the antenna
was a loaded resonant dipole tuned to 80 and 40 that sort of worked on
30 and 15, and was fed by vintage 75 ohm Belden "kilowatt twin lead." To
use it on 160M, I ran two wires down to both sides of a wrought iron
fence that ran around my front yard (both sides because it was broken by
a gate). The wire and the fence functioned as a counterpoise, and the
vertical wires radiated (and modified the resonance). As it turned out,
that antenna loaded that way worked better on 80 than it did loaded as
dipole, simply because the dipole wasn't very high (35-40 ft). I'm
reminded that my buddy KK9H used the air conditioning ducts in his home
as a counterpoise on 160M. We've worked several times since I moved to W6.
There are photos and a description of my Chicago antenna weedpatch
(won't dignify it by calling it an antenna farm) in
http://k9yc.com/LimitedSpaceAntennasPPT.pdf
73, Jim K9YC
On 8/27/2019 12:38 PM, Grant Youngman wrote:
But I fail to see the rationale of using the AX1 as a “counterpoise”.
For quick low profile portable, the AX1 works as well as you can expect a very
short loaded radiator to work. For that purpose it’s easy, quick on the air,
and does fine.
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