On 4/28/16 5:49 PM, Roger (K8RI) on TT wrote:
Just another thought:
30' pole on the roof supporting 5 center fed, half wave sloping
dipoles. I have used a couple, but if you have the room, use the 5
switched dipoles. I believe it's in either the ARRL handbook, or the
Antenna handbook.. They are simple, seem to work stateside and DX.
Switched as in the handbook, the have a little gain and a bit of a F/B
that really helps.
Even 2 or three will give a bit of directivity. I'm thinking of
switching to 75/40 fan dipoles and experiment with the 5 antennas
instead of just a single monoband on 75 and one on 40 at present. Wire
is cheap and easy to experiment with. I've worked all continents with
just two 40 meter slopers and an AV640 (on 40) at 25 feet.
I would think that two dipoles, with some sort of adjustable phase
combining network might be the optimum strategy. A dipole isn't going
to have good directivity for the main lobe, but can have a pretty good
null to place on an interferer.
There was a clever scheme in one of the antenna compendiums where there
was a adjustable LC, a combiner, and a DPDT polarity reversing switch.
You adjust the two knobs on the LC to minimize or maximize the signal as
desired, flip the switch and what was maximized, is now minimized.
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