1) If you have the space and work hours and money isn't an issue - go with
120 1/4 wave buried radials.
That is a myth that stems from the FCC not requiring a ground system proof
of performance when more than ~110 radials are used, and 120 radials is
pretty much a waste of time for hams. At my location on 40 meters, somewhere
about 15 radials got on the flat part of efficiency curve and on 160 about
30-40 radials gets really flat for changes.
The only reason I have 100 radials on my 200 ft tower is I had the wire, I
have a radial plow, I wanted lightning protection, and I used to hang
horizontal antennas in that area so I wanted a counterpoise under them.
2) Good soil doesn't require as many radials.. someone was commenting on
the AM towers be reconditioned - using elevated radials.
That isn't a good rule. There are two cases of zero loss, perfect
conductivity and no conductivity at all. Someplace between the two, loss
will peak.
I have a mixture of soil from swampy rich soil to red clay. My 40 meter
vertical test was over a patch of red rocky clay, and it only needed ~15
radials to get on the flat part of the curve.
3) Elevated radials work better with poor ground conditions. Higher with
lower bands.. 15-25ft on 160m..
That's not a good rule, or at least it is not a rule that has been
substantiated.
4) You don't need as many elevated radials as ground radial.. (debate
about 4 to 12 or so?) I'd say 12 but would like to see a study. Some
say 2 or 4?
Some, like N6LF, say 16 to be safe.
Once you have the control antenna it's easy to start comparing real world
results. How's 12 radials sound? Cut 4 off.. how's 8 sounds.
The K.I.S.S. approach.
I don't think it would be very hard to disconnect some radials and say -
"how's the signal now?"... two guys with a walkie talkie making doing
some tests cutting some wires etc...
You would have to actually remove the radials to see the full effect. The
best way is to start with empty soil and work upwards, not cut things.
An A-B test comparison to a stable reference would be simple and reliable.
73 Tom
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Topband Reflector
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