Lloyd N9LB, you may be correct, but I prefer cited facts and data to
back a statement. So to that end I went back and did some reading.
In addition to the previous paper I cited, see page 10 here:
That's an excellent resource in other ways for the medium wave
To help the fellow who asked about radial plowing, here's some
diagrams detailing installation and a radial plow:
Arch Doty wrote a paper in 1983
(http://home.fnal.gov/~atkinson/Doty-Radials.pdf) that details results
of his research on radials above ground, on the surface and buried,
both insulated and bare. He has a variety of conclusions and finds
insulated on the ground is better for collecting return currents, if
elevated is not possible. Several factors vary measurements:
length, soil type, frequency, number of radials. I generally maintain
that if you must bury radials, a few inches one way or the other do
not matter, but the sources I read above, mentioned in various ways
that the return currents in the earth are a skin effect phenomenon,
seems to support your statement that depth matters in small
increments. So in the future I'll advise laying of radials on the
surface if they do not need to be protected.
Also important (from what I read) is that many many radials close in,
are very good for antenna efficiency when a short vertical radiating
element is used (i.e. inverted L). In other words, it won't hurt to
double up on 60 radials with another 60, each of 20 feet or so, in
between each long radial. This is a good time of the year in the N.
Hemisphere for laying down radials as the growing season is over for
most of us.
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