RE: [amsat-bb] GRRRRRRRRRRR!

[Bruce Bostwick <lihan@xxxxxxxxxxxxxxxxxx>]

>I have tried putting all the 2m elements of an Arrow on one boom, and all
>the 70cm elements on the other boom, but I could never get the antenna to
>tune that way. That was originally the preferred route, believe me!

May have been element spacing, or things like the mount getting into the E
field of one plane or the other.  With a crossed Yagi, you'd pretty much
have to end mount it or mount it on a nonconductive (and not terribly
dielectric) mast, and if the feedline doesn't snake through the boom, it
will have a certain amount of effect on the near field of the driven
element as well.

Phasing the two sets of elements could be fun though, especially if you can
come up with a phasing scheme that allows you various combinations of 0,
90, and 180 degrees phase delay on each element -- mount them in an X
pattern and set up the right phasing combinations, and you could easily get
vertical, horizontal, RHCP, and LHCP by flipping switches.

Here's another thought:  Feed those two sets of elements in phase, but
*modulate* them in opposition, perhaps with a sine/cosine preemphasis, and
you get polarization *modulation*.  I know it's probably been done, but I'd
like to see it and get some idea of the bandspread.  My suspicion is it's
narrow .. ;-)


"Orthodoxy is orthodoxy because it won, not because it is true." -- Bp.
John Spong
 "Power takes as ingratitude the writhing of its victims." -- Rabindranath
Tagore
               --... ...-- -.. . -. ..... ...- -...
         Bruce Bostwick  mailto:lihan@ccwf.cc.utexas.edu
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