Message-ID: <000801c1c747$e05ed000$466a68d5@oemcomputer>
From: "mike.dennison" <mike.dennison@ntlworld.com>
To: rsgb_lf_group@blacksheep.org
References: <DDC408CAE72CD511827A0002A5131CD6D9F4BD@exc_wil08>
Subject: LF: Re: RE: Re. Loops
Date: Sat, 9 Mar 2002 08:53:25 -0000
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Bill A wrote:

> > ......so for tranmitting it would seem to be a good idea to have a
bottom
> wire on, or in the ground.
> The problem is that the soil losses become fairly large. Think of the loop
> wire with a huge donut-like AC magnetic field surrounding it. This field
> doesn't seem to like the composition of the ground, which in effect, adds
> series resistance to the loop circuit. I find the best compromise in
> reduction of soil loss Vs maximizing the loop area by keeping the lower
> conductor at least 5ft above ground. This distance could vary depending on
> the soil type. The soil here in the Boston area, is composed of at least
60%
> sand, covered by a thin layer of top soil.
> >This would have the added advantage of making it possible to use a very
> thick or multiple thick >wires for this part of the loop thus reducing the
> total loss resistance by almost 50%, with a
> >consequent considerable increase in efficiency.

For the bottom wire of my 73kHz loop, I used 3-core mains flex at 5ft above
ground. My wife used it as a washing line!

Mike, G3XDV
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