[Lf] [Fwd: Re: LF: EARTH RESISTANCE]

[Andre Kesteloot]

-------- Original Message --------
Subject: Re: LF: EARTH RESISTANCE
Date: Mon, 16 Dec 2002 16:32:01 EST
From: WarmSpgs at aol.com
Reply-To: rsgb_lf_group at blacksheep.org
To: rsgb_lf_group at blacksheep.org

In a message dated 12/16/02 1:30:09 PM Eastern Standard Time,
g3kev.ham at virgin.net writes:

<< Dick has indicated that Earth Resistance gets higher when the ground is
wet. That seems strange and contrary to accepted theory. The ideal ground
plane for a vertical is on a wet plain or preferably positioned in the 
middle
of a lake or in the middle of the Ocean. Have I missed something and 
read his
observation incorrectly. >>

I think both points of view are correct, but under differing prevailing
conditions.

The type of soil may make a great difference in whether moisture 
enhances or
degrades radiated signal.  Where I live now, the soil seems to experience
increased dielectric loss when wet; whereas, in other locations, I found 
the
opposite to be true.  Because of the greater skin depth of the earth as the
wavelength increases, I would expect the effect to be more pronounced at LF
than MF or HF.  Dick's data may be partial supporting evidence that this is
so; in which case, it's even possible that some soils will be better at MF
when wet, and better at LF when dry.  Sounds like a fertile field for
investigation (no pun intended).

As for bodies of water, a freshwater lake turns out not to be as good a
location for a ground plane as I once thought.  I have tried this 
approach at
LF and MF at a few very different locations, always with less signal than
expected.

Seawater is quite a different matter!  At MF, especially, it does truly
wonderful things for signals.  Along with our fleet of VHF FM public
broadcast stations, I oversee one small mediumwave station on the Georgia
coast which is less than listenable more than about 20 miles inland.
However, it has a coastal coverage range from St Augustine, Florida, to
Hilton Head, South Carolina.  (In fact, do we have any readers in Bermuda?
If so, I invite you to give a listen on 1190kHz.)

John