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Re: Fwd: Antenna for Mir SSTV RX



At 06:14 AM 1/25/99 PST, Mike Thompson wrote:
>I had the same questions, and I ran a crude test. I switched between a 5/8
>wave vertical and a 1/4 wave vertical while MIR went through a rather high
>pass (about 50 deg. max. elevation). As one would might guess, the 5/8 wave
>vertical seemed to have a better signal at the beginning/end of the pass,
>and the 1/4  wave vertical seemed to do better in the middle of the pass. I
>have also tried my 11 ele. yagi -- rather tough manually!

Now can we wish for the SSTV to switch to 436?  ;-)  On that band a short
helical would work fine -- just point it at Mir.  2 meters makes a helical
sort of impractical .. 

Seriously, getting the elevation, azimuth, AND polarization right with a
1/4 wave whip on the HT is pretty challenging.  The 5/8 wave vertical,
since it's almost like a short phased array, will concentrate its signal
and sensitivity much nearer the horizon (which is why they're so great for
terrestrial repeater use!) while the 1/4 wave will have much more
high-angle performance.  A dipole would work even better if you have a
rotator to match the polarization ..


Bruce Bostwick                 KD5BIV                   Austin, TX
                   mailto:lihan@ccwf.cc.utexas.edu
                       mailto:kd5biv@qsl.net
                  http://ccwf.cc.utexas.edu/~lihan/
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