Topband: Evaluating shunt fed tower ground system

[nl7z@mtaonline.net]

I am in the process of improving the ground under my shunt-fed tower, and I
would like to gather some input on this project.
First - the details on the tower system.

125' Rohn 25 + Hygain 205CA.

I extrapolated from the only charts I could find on calculating the
electrical length of this system, and my best guess is somewhere around 135
degrees electrical length.

I have used two different instruments to measure the feedpoint impeadance,
and they both agree somewhere at 37 Ohms.
I realize that I have no way of knowing what part of this is the radiation
resistance, and which part is the ground loss.

At the current time, there is only 22 radials connected - which I plan to
increase to about 100 radials.

My question is mainly, what impedance should I be seeing with this
electrical length antenna?

I know that I will keep measuring the feedpoint while I add radials, and
stop when I reach diminishing returns.
Thanks
Kevin
NL7Z



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