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Europa-List: re: Antenna Tuning

Subject: Europa-List: re: Antenna Tuning
From: Fergus Kyle <VE3LVO@rac.ca>
Date: Mon, 29 Mar 2010 15:52:44
Cheers,
        I might mention something while tuning an antenna which might make
some difference. Normally an antenna up and clear  will reflect the
qualities desired. But at our freqs, it=92s important to ensure that 
nothing
resembling a nearby freq exists within about a =BD to 5/8 wavelength ( a 
bit
less) ' say 300/127 m or something less than 1.5m. All this depends on
orientation etc, so if a UHF or higher ferq is off the end of your 
tailplane
dipole, not much loss of a spherical power plot. BUT if you insert a 
=BC-wave
vertical in the plane of the diploe within a meter or so, expect the 
pattern
of the latter=92s power plot to be skewed and it won=92t radiate 
spherically '
that is pieces of the pattern will be missing power (maybe straight 
ahead
and you have to turn the a/c 30 degrees to get the tower ahead to pay
attention). High is assumed but clear is also needed.
Nuff sed.
ferg


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