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KD7MW's dirty double-antenna tricks




For those wishing to save wear and tear on their rotators, let me share a
method that I've been using for Mode A and T, especially on passes above 40
degrees.  If you don't have a beam, a variation on this theme might help
you, too.  The key is that two antennas are better than one, and a coax
switch is fast and easy to operate.  

I'm fortunate to have both a circularly polarized beam and an eggbeater on
2m.  I point the beam at either the satellite's rise or set azimuth on a
near-overhead pass.  For a pass that covers significantly less than 180
degrees of arc, I point it so that the front and back of the beam are each
equidistant from the rise and set points.  For example, if a pass rises at
25 degrees and sets at 155 degrees, I point the antenna at 0 degrees or 180
degrees.  

I leave the beam where it is for the entire pass.  I use the beam when the
satellite is near the horizon, and switch to the eggbeater when it rises
above 25 or 30 degrees.  Above this elevation, the satellite is near its
closest approach and clear of any ground obstructions, so the beam isn't
necessary. All this means two flips of a coax switch per pass, rather than
all those rotator bearing-crunching starts and stops every few degrees.

All I'm doing is matching my antenna's angle of radiation (and reception)
to the satellite's position, and taking advantage of the fact that many
beams work pretty well off the back.  :-) Eggbeaters and turnstyles radiate
and hear best upwards.  Verticals and yagis radiate sideways.  The
helf-power beamwidths of my 2m yagi (10 feet long) are about 40 degrees.
That's a lot of leeway.

If you don't have a 2m beam, you could try combining an eggbeater or
turnstyle (high angle) with a ground-plane, J-pole, vertical or gain omni
such as an Isopole (low angle).

I don't have an HF beam.  But I've found a way to improve satellite
reception on 10m. I switch between my R7 vertical (satellite near the
horizon) and a 10m turnstyle in the attic (satellite ~30 degrees and up). 

Standard disclaimer:  I'm not a rocket scientist, and I don't play one on
TV.  Batteries not included.  Your mileage may vary.  So there.

73 from KD7MW
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