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Re: RHCP



Jerry:

As far as I know (mostly from reference to the ARRL Antenna Book), you can 
achieve elliptical polarization by mounting two yagis to the same mast with 
no offset, and feeding them 90 degrees apart with a phasing line.  With a 
relay and a few tees, you can even be able to select LHEP or RHEP!

The photos I see in the Antenna Book seem to indicate that the antennas are 
1 to 1 1/2 wavelengths apart on the boom, and are each rotated 45 degrees 
from the boom, so that they are 90 degrees from each other without either 
having elements in the same plane as the boom.  I suspect this is 
significant, as one being in-plane with the boom, and one being 90 degrees 
to the boom would probably result in two different radiation patterns, and 
reduce chance of any sort of circularity.

A few other comments from the Antenna Book are worth noting:
    * "As long as the separation between antennas is small, performance 
should be nearly as good as when both sets of elements are on a single boom"
    * "There is no operational difference between true circular 
polarization and the polarization diversity provided by this system.
I hope this helps.  Personally, I'm pretty happy with my 6 turn helix for 
435 uplink to AO-40.  Circular polarization with no lossy phasing 
arrangement, and it worked well enough to create a few pileups on Field Day!

73,

Paul W4SKI

At 09:00 PM 8/1/03 +0200, Jerry wrote:
>Hallo to all
>
>I'v have question about feeding 2 ant for RHCP.
>Using at the moment a home made RHCP 2*14el on 70cm without any problems of
>feeding it,I wonder how I need to feed 2 yagis,one H and the other placed
>V,some distance between...
>1° is there a certain distance between the 2 antennes to be used?let's say
>center boom-center boom
>2° do I have to put one antenne 1/4 ahead,keeping in mind  using the same
>feedline-lenght?
>
>I just want to try this setup to see what is difference between one
>crossyagi,setup 1,and setup 2 with  the 2 antennes placed apart.(H and V)
>
>Hear you on the birds
>73's
>ON4CJQ,Jerry
>
>
>
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