I wonder if anyone knows how much ground conductivity varies within the
broad contours shown on the USGS map? For example, my area of West
Virginia is listed in the 2 millisiemen countour, probably because much of
the area is karst geology with only a narrow skin of soil over
limestone. However, the area where my tower is footed is an ancient river
bed, with 6-7 feet of usually moist soil. It seems (from experience only)
to be rather better than the general expectation of poor ground. I presume
that the depth of soil needed depends in some large part on the skin depth
at the frequency of interest, but how far from a vertical antenna does soil
conductivity continue to affect field strength?
73, Pete N4ZR
At 09:11 AM 10/19/2007, Ken Bessler wrote:
> > From: km1h@jeremy.mv.com
> > To: jim@audiosystemsgroup.com; towertalk@contesting.com
> > Date: Fri, 19 Oct 2007 08:57:45 -0400
> > Subject: Re: [TowerTalk] Inverted L for 160 meters
> >
>
> > A lot depends on the ground conductivity. With 32 radials 12' high I never
> > waited in pileups very long. My ground conductivity is about that of
> granite
> > since it is only a foot or so below ground.
> >
> > Carl
> > KM1H
> >
>
>Incase any of you are wondering what the ground conductivity
>is in your area, I have a map from the USGS showing just that
>for the continental US. It is free to download at my website:
>
>http://members.cox.net/kg0wx/
>
>Ken
>
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