[TowerTalk] Soil Conductivity/

[Pete Smith]

At 10:44 PM 5/26/00 -0400, Tom Rauch wrote:
>...Conductivity varies all over the place in a short distance, in an area 
>like Atlanta. You can find areas of less than 1, and areas of 15 
>mS/m or more, measured on 1 MHz in the Atlanta area.  
>
>You can't measure it with ground rods, you can only measure it by 
>measuring the attenuation of a signal travelling along the earth.
>
>I don't worry about ground conductivity, since I don't work a lot of 
>extended groundwave on HF. I only worry about the first few 
>wavelengths of distance from my antenna.

Well, models of vertical antennas certainly show profound effects on the
far field from changes in ground conductivity.  Doesn't that translate into
sky wave signal?

John Belrose (VE2CV, I think), published an interesting method of measuring
ground conductivity here on Towertalk a few years ago.  Essentially, it
involves rigging a low dipole a known distance above ground and measuring
its resonant frequency.  Then you take NEC-2 or better and tweak the ground
variables until a modeled dipole matches the physical one.  I haven't tried
this, but it certainly looks like it should work.  Comments?

73, Pete Smith N4ZR
n4zr@contesting.com 



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