"hasan schiers" wrote (I'm still waiting for
clarification on your formula, btw)

====================================

There's a mistake in the formula. I copied it incorrectly from my old
notebook.

The wavelength Lambda doesn't come into it. No wonder you asked what
units Lambda is in.

The correct, more simple, formula is -

RadRes = 18 * ( 1 - Cos( 180 * H / ( H + L ) ) ohms,

Where H = Height, L = Length of horizontal section, and the angle is
in degrees.

Your antenna is 45 feet high and 70.8 feet overall length. (It doesn't
matter what the measurement units are. It's just a ratio.)

And so your radiation resistance, at 1/4-wave resonance, is 25.4 ohms,
give or take a few ohms.

The only thing I'm unhappy about is making impedance measurements at
the other end of 55 feet of coax. You need to know the exact Zo and
velocity factor and length of this cable, plus some accurate
calculations. The technique is fraught with error.

Get your hand-held antenna analyser right to the bottom end of the
antenna wire, on the R + jX range, and immediately adjacent to the
focal point of the radials. And hope you don't get interference from
the local, high power, MF broadcast station. But you are already aware
of this and I mention it for the benefit of the lurkers.

I assume you measure SWR only to estimate antenna bandwidth. At the
other end of 55 feet of coax anything can happen to SWR. But if
bandwidth decreases as the number of radials increases then at least
it is going in the right direction. I don't think you will squeeze any
other information out of it.
----
Reg, G4FGQ