> 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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