On 5/6/2025 10:33 AM, Steve Lawrence via Topband wrote:
I have no radials either. No place for them. Just two copper ground rods at the
tower base.
That's a LOUSY counterpoise -- the earth is a big resistor. I agree with
other comments. I've also base-loaded a #10 wire sloping from the top of
a 120 ft tower that supports the smallest SteppIR and a 30-ft long 6M
Yagi, against four elevated radials. The feedpoint is about 60 ft from
the tower. I've added on-ground radials to the base of the tower so that
it's an efficient reflector, so I get a couple of dB of gain in the
direction of the slope. The catch is that the tower is surrounded by a
dense redwood forest, which sucks about 9 dB, so the Tee vertical, in
the middle of the clearing for my house, is much louder.
BTW -- verticals can have a lot of interactions you'd never think of.
Rudy has written extensively about that. My Tee vertical came two years
before my tower, and when I added it, both NI6T and N6BV asked me
(separately) if I'd studied interactions. The next summer, I did an
extensive EZNEC study (weeks) based on carefully measured data for
locations of the tower and the Tee. Turns out that the combination of
thee tower and the sloping wires (one to the west, a second to the east)
gives be a couple of dB to VK/ZL if the coax short to those sloping
wires is shorted in the shack and the coax is a halfwave, and the Tee,
if shorted, serves as a reflector for either of the sloping wires,
pushing their lobe to the north about 45 degrees.
For those who don't know, N6BV is long retired editor of the ARRL
Handbook, Antenna Book, and other ARRL books on antennas; NI6T is also a
very sharp engineer a DXpeditioner, and a great topband op. Both are
serious contesters, but both, sadly, have been deep into Parkinson's for
a while.
73, Jim K9YC
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