FWIW:
Talking the 160m problem:
The subject of counterpoises, ground planes etc is a subject in itself.
My 02c worth:
There are two main questions:(a) How to configure the antenna/earth/radial
etc system so as to get current flowing in the thing.
(b) What the effect of the environment (salt water, seaside, mountain top
etc) and whatever arrangements conspire to get most of the radiation at a
reasonably low angle.
My limited experience: Made an inverted L out of my 50ft tower and tribander
plus a 20ft topmast of alumin tube. One thick insulated wire run up tower
and off the top of the top mast (up 70ft) and tied off to tree. Gave 150ft
wire in all (about 80ft in the L loading wire, sloping down to about 50ft
high at end.
Fed with gamma match wire connecting at 40ft level, held off 3ft by
spreader.
Tried loading against a collection of maybe 16 random length radials, most
only 50-60ft. Had little joy until I made two radials like a 160 m low
dipole, snaked around my boundary fence and one leg along top of fence of
kind neighbour. Grid dipped to 1830. Connected to the braid of coax at
feedpoint.
Series variable C feed to gamma wire.
Effect was obvious and immediate. Thing tuned up, could bring swr to 1:1 by
adjusting C and fiddling gamma match spacing from tower.
Should mention my ground quality very poor.
Did not connect the random radials.
This set up could work Eu from ZL whenever they could be heard.
My take on this: Get some part of the system that you know is resonant in
band, maybe even one 1/4 radial would do. Then there is a good chance that
the rest of the system will tune up against it.
Of course if you can come up with a great radial system ,the above would
not apply.
Quarter wave inverted Ls may not be the greatest, but given a reasonable
earth system give a good bang for the buck. Get the impression that most
users are reasonably pleased with them.
--
Barry Kirkwood PhD ZL1DD
barrykirkwood@gmail.com
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