Topband: Measuring field strength

[Tom Rauch]

> let's see if we can obtain an accurate change in field 
> strength from added
> base resistance in NEC-2. Here's a 7 MHz vertical mounted 
> 1' above average
> Sommerfield GND. The vertical has 16 resonant radials.
<SNIP>
> The relative field strength is exactly as one would 
> calculate given the
> source current into 36.9 ohms (in this case we can 
> 'assume' that the radiation
> resistance is 36.9 ohms).

I'm sure we all agree if a lumped resistance component is 
placed in series with a fixed load resistance-- Ohm's law 
will work as expected.

I think the point being missed is the "ground resistance" 
measured at the base of a vertical by watching the impedance 
change at best has only a very poor relationship to the 
actual ground loss in the antenna.

73 Tom