Andre' Kesteloot wrote:
vernall wrote:
> [...]
> If sky wave mode is what
> is actually being sought after, then it may well be worth experimenting
> with a horizontal "dipole"?
assuming the above hypothesis is valid, why not a horizontal loop, which
could be much smaller than a dipole ?Andre' N4ICK
I was not meaning to restrict the idea to a dipole, but rather to
stimulate a re-think on why horizontal polarisation may be worth a try
for sky wave mode of operation. A "loop" has less radiation resistance
than a "dipole" when the size is small. But I am suggesting a rather
large affair, and a long straight wire could be easier to install and
maintain than a loop. But consider whatever suits the available site.
As well as the long wire used on LF by ZL1WB, I can say that here in
Wellington myself and Andrew ZL2BBJ have done some receive tests and
impedance measurements on a big V antenna at the Quartz Hill HF DX club
station (call sign ZL6QH). By connecting both feeders in parallel, so
the V is like one big wire, the measured impedance is slightly
inductive, which indicates the electrical length is just over a quarter
wave at 180 kHz. The resistive component is not far off 50 ohms, but
most likely it is ground loss swamping the result. We intend to do some
LF transmitting in due course, on what is essentially a long wire with
mostly horizontal aspect, so we will see what happens.
I have also applied to have the 136 kHz band added to my Low Frequency
Permit. Nothing like being an optimist ....
Bob ZL2CA
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