I need some educating. I always believed that it was the LOAD at the
end of a coaxial line that established the SWR and phase shift. With
a receiving antenna, that load is the receiver or, in the case of the
4 square, the phasing box with its included circuitry, and ultimately
the receiver. If this is true, why is it necessary to match the elements
to 75 ohms other than for power transfer? Mark, WA1ION, has done some
experiments using just transformers to "match" various antenna types.
I also read that an antenna could be "matched" by using a transformer
that steps up the impedance to the same value as the antenna reactance.
In other words, if a short vertical had a reactance of -1200 Ohms, it
could be "matched" to 75 Ohms with a 1-16 ratio transformer. I put the
word match in quotes because this is not matching for SWR, just for
reasonable signal transfer. Why would this not work for a 4 square
system?
I agree that all elements have to produce the same amount of signal
and introduce the same relative phase shift to the signal. But, if
you are not required to maintain 75 Ohms at the feedpoint, it would
seem that any conductivity changes in the ground would affect all
elements equally obviating the necessity for a low loss ground. You
would only need a minimal ground to compensate for changes in ground
conductivity in the vicinity of the elements themselves.
73, Roger
--
Remember the USS Liberty (AGTR-5)
http://ussliberty.org/
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