First congratulations Alan on your commitment for a 4-square on 160.
I use a 90 foot top loaded similar aluminum vertical here in Oregon. I find
the use of four guy wires very convenient as it allows the use of the "falling
derrick" method of erecting 90 feet of not so stiff tubing by one person. See
"http://www.n6rk.com/irrigation.html"; for a good description of how this method
works.
On your top-loading wires you have a choice to make. I use 4 portions of the
top guy wires at 25 foot length which makes the entire vertical (with 64
radials) resonant at 1850 Khz. I use an L network to step up the antennas
impedance from 25 to 50 ohms.
If you make your top-loading wires 43 feet as you suggest you may be able to
get by for matching with a simple series capacitor as it is my guess your
antenna wil be a little low in resonant frequency. Something you should maybe
use an antenna simulation software for if you have not allready. Of course in
the 4-square mutual coupling will make impedance changes as well. I think you
should make the top loading configuration based on a thorough look at the
resultant impedances for the 4 square configuration. Perhaps there is an
optimum length/configuration for the top-hat.
My back is shot from 20+ years of lifting grain sacks, but with this method
I still put up the 90 footer by myself.
Lee K7TJR Oregon
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