Hi Bob,
The GEM, coke breeze, and magnesium sulphate are all bulk effect
measures designed to permit more efficient _connection_ of an
earth terminal to earth. While they all modify the conductivity
of the immediate surroundings of a ground rod, they do not change
the basic RF loss characteristics of the earth to any meaningful
degree. Specifically, they don't reduce the skin depth for RF
current flow to a value low enough to prevent the bulk
interaction of the lossy earth with the near field energy storage
fields of the antenna. When applied to a large area (outside GEM
encasement of an electrode), they also have the disadvantage of
leaching out of the soil over relatively short time periods.
Even if they would be effective, they would soon make a ground
screen installation look cheap.
A conductive metallic screen of sufficient density is the only
effective measure so far discovered for permitting an antenna
mounted near the earth (near enough that the earth violates the
near field zone of the antenna) to operate at its highest
possible efficiency.
73, Eric N7CL
>From: Bob Wanderer <aa0cy@nwrain.com>
To: <towertalk@contesting.com>
>Date: Mon, 11 Oct 1999 13:28:35 -0700
>
>Isn't it interesting that ARRL accepts GAP advertising. It used
>to be that claims had to be proven before ads were accepted. I
>guess that's true no longer.
>
>I was satisfied with the performance of my Titan (as is) in
>Nevada. I guess that's the crux of the issue.
>
>Soil Conductivity can be improved by "salting" the earth with
>GEM, coke breeze or MgSO4 (epsom salt). I wonder if that would
>work as good as the radial field Phil suggests.
>
>73,
>Bob AA0CY
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