[amsat-bb] Linear vs Circular Polarization

Brady Gordon ac0xr at lowswr.com
Wed Apr 12 21:11:53 UTC 2017

Hi Everyone,

I'm working on building a pair of crossed yagis for 2m and 70cm, and I have
some questions.  I apologize if this has been discussed before, but I
couldn't find answers online so I was hoping you all could help me out.

First, it seems easiest to me to build an antenna system that can either
switch between vertical and horizontal linear polarizations, or between
right hand and left hand circular polarization.  Which would be more
useful?  And is it worth the extra effort to build an antenna system that
can switch between all four polarizations?

Also, I've been looking at the different ways of achieving circular
polarization.  I like the idea of using mechanical 1/4 wave separation
between the two yagis so I don't have to cut phasing lines.  Would it be
possible to switch polarizations by putting a relay at the feedpoint of one
of the yagis and switching which side of the driven element the center
conductor and shield of the coax goes to?  I've never seen this done
before, but it seems to me it would work.  Any thoughts?

Thanks and 73,
Brady AC0XR

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