I can appreciate reasons why MW BC stations and LW transmitter sites would bury
their radials deeply, plus they could be expected to have the equipment and
deep pockets to do it. But in my opinion, anything below a few inches is
unrealistic for the vast majority of hams, and in practically any case,
unnecessary.
My radial system consists of 120 quarter wave wires (16,000 ft in all).
Overkill for amateur purposes I know, but I stumbled upon an extraordinarily
good deal for a big spool of #12 bare soft-drawn while living out-of-state
back in 1974. When I finally got round to building the radial system in 1983, I
fabricated a homebrew plough, attached to a walk-along garden tractor for
laying them. With one helper, we laid the whole radial field in four days.
They average 2-4 inches in the ground. Our red clay soil here is very benign:
PH neutral and the minerals don't corrode copper too much. Occasionally, I'll
dig down to randomly inspect a radial and even to-day the wire looks virtually
intact other than for a greyish patina.
A copper thief would have a VERY hard time pulling up the wire. I had to
temporarily move a radial out of the way a few years ago for another
construction project, and it was all but impossible to pull the wire up though
the clay soil and sod. I ended up manually slitting the ground with a spade
the day following a good rain, in order to pull up the wire without stretching
or breaking it; that was more difficult than manually laying radials using a
hand tool.
The writer of the article in the antenna book most likely just copied directly
from a broadcast or commercial communications manual without giving serious
thought to the different situation amateur practice would present. I suspect
very few hams attempted substantial 160m radial systems during the waning days
of the Great Depression before the war broke out. Probably because of the WWII
shut-down and the uncertainty of the 160m band and LORAN following the war,
this wasn't revisited and corrected until years afterwards.
Don k4kyv
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