Topband: Re: Ground system

[Tom Rauch]

> My gut feeling is that these parameters don't change much with
> frequency. 

The problem with measuring ground is the skin depth is quite deep 
on 160 meters, and the effect you see is the accumulated effect of 
many layers and types of soil with varying moisture. 

Even with homogeneous soil, which few of us have, conductivity 
varies with moisture.  Even if we know the effective conductivity, we 
know it only for one spot near the dipole!

What we measure on 40 meters can have nothing to do with 160 
meters, but the low end of 80 is probably close enough to 160 to 
be useful.

The ARRL used to have a test with ground rods, but I think that 
test has been removed from books now.  It was useless, because 
the measurement was done near the surface and nearly at direct 
current.

It's not possible to model soil accurately, except as an average 
effect.  Even then, it's still an educated guess.
 
73, Tom W8JI
W8JI@contesting.com 


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