On 1/10/16 8:56 AM, Roger D Johnson wrote:
Another factor not usually considered by hams is that conduction through
the ground is NOT the same
as conduction through a copper wire! A copper wire has a copious supply
of free electrons and will
happily conduct increasing amounts of current until it melts. In soil,
the conduction is by ions from
metallic salts in the earth. The supply of ions is finite and when all
are being used to conduct electric
charges, the resistance rises sharply. The soil has gone into
"saturation".
do you have a reference for this? I'm interested in a more technical
description of the phenomenon.
I'm familiar with some other soil and tissue conductivity phenomena
relevant to RF having to do with the ion mobility (e.g. the Cole-Cole
model which is used for all sorts of things at all sorts of frequencies:
prospecting for ore, measuring the ripeness of produce, and RF imagery
of human bodies)
A lightning ground system
has to be designed to dump the current from a strike into a large
"volume" of earth capable of conducting
the strike current.
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