Topband: Tower shunt feed modeling?

[Nancy & Steve Lawrence]

I have a 54 foot free standing 3 section crank up with 3 antennas on the
mast providing a good amount of top loading. I've installed a gamma rod
from the ground to the top of the bottom section 15 inches out. With an
omega match I can tune this for 75 and 80. By significantly increasing the
series and shunt capacitance, I have it working on 160 as well. The shunt
capacitor is the frequency tuning critical element. Bandwidth on 75 or 80
is 50 to 60 Kc. On 160 it is about 2MHz (yes MHz) - lossy?

Question: Suggestions on modeling this? I'm more interested in the
mathematics than a canned program but any suggestions appreciated. I have
ON4UN's Low Band DXing book.

73, Steve WB6RSE




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