I had all the mentioned dilemmas and have some answers. But they are
specific to GA, some 100 miles NE from W8JI.
My new vacation location has JkMidTri40 on a 100' tower. Works pretty well
so 40-10m covered. I shunt fed the tower on 160m. With 8 radials, it was
6db better than inv L with 4 elevated radials. With 32 radials, 8 db
better. 160m covered. .
For 80m I had endfed and OCF around 50'. Similar
unspectacular performance.
I tried loading the tower on 80m. Very critical tuning, small BW, and low
signal, but it rivaled Beverages on RX DX, suggesting a very low angle of
radiation.
Then I tried a single K8UR style vertical dipole. Signal strength a bit
below the OCF.
Then a 70' vertical wire separated 4' from the tower, a la K9MA. Very weak.
My lowest guys were EHS but insulated at top and they resonated at 3.1 MHz.
After replacement by Phillistran, the vertical was much stronger but not as
strong as OCF.
4SQ can be made as K8UR vertical dipoles, classical verticals, or ON4UN
with 1 elevated radial. In order not to destroy the BW of 160m, K8UR would
have to have transformers by the 4sq box, and baluns by the feedpoint. So I
decided to set 4 sq ground based and use a DXE 4SQ box.
Initially just 4 1/8 wave radials per vertical over the 160m radials. A
couple of db better than OCF. Then added to 20 radials since the grass was
becoming too big to add more. No measurable improvement and F/B slightly
worse.
For comparison I added an 80m dipole off the top of the tower in the EU
direction. Similar performance to 4SQ . But 4SQ is some 10db better to W6,
which indicates that one of my wire antennas may act as a reflector to
the 100' dipole in the EU direction. Also the feeder to the dipole is
partially messing up the pattern of 4sq.
20 radials are not too many although they are on top of 36 radials for
160m. I tried soldering 80m radials to 160m radials. No change in impedance
meaning the 160m radials were already doing their work without tying. Tried
2x 50 wire mesh advertised by some as ultra-efficient, with only as much
effect as 2 25 ft wires. Perhaps 4sq will be spectacular in the winter
season after more radails are added.
This whole 80m affair took an enormous amount of time and testing. From the
perspective, two criss crossed dipoles at 95' might have been just as good.
But they could also affect the pattern of the beams, and my comparisons may
still be affected by interactions.
The advantage of 4SQ is complete coverage of 80m at low SWR. Also
directivity if there are no beverages. If I were to do it again, I would
have tried perhaps one elevated radial a la ON4UN, exploiting 160m radials
beneath, and if the height was insufficient, to bend the top.
Many of my problems are caused by a single tower. With 2+ towers the
interactions would be limited.
Ignacy NO9E
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