[amsat-bb] Re: AOP-1 Circular Polarization?

[Greg D.]

Actually, I was thinking about this today...  There was an earlier thread which discussed the off-angle performance of a crossed Yagi, and if I recall, the pattern becomes elliptical as you move off the antenna's bore sight.   If this is true, then I conclude that it would be better to mount a crossed Yagi in the + orientation, vs X, as that way one of the two antennas will be properly aligned for an off-angle linear station.  For satellite work, with accurate keps, this is probably not a significant issue, but for terrestrial work and other situations where the target's position may not be known or tracked, + should be more forgiving than X.  At least, that's my theory.

I kind of hope I'm wrong on this...  I just got a new 70cm antenna from a swap meet today, and it's already mounted in the X position.

Greg  KO6TH


----------------------------------------
> From: w5rkn at amsat.org
> To: amsat-bb at amsat.org
> Date: Sun, 18 May 2008 16:42:02 -0500
> Subject: [amsat-bb] Re: AOP-1 Circular Polarization?
> 
> Assuming the antennas you reference do produce circular polarization, 
> radiation wise, it doesn't matter whether you mount them in an X or + 
> orientation. The only difference would be the phase of the radiation, and 
> you are not concerned with that. There could also be a difference between 
> right- or left-circular polarization, but whether that matters depends on 
> the polarization the the satellite's antenna. But X or + does not change 
> that.
> 
> There might be some mechanical reason for an X or +, such as weather 
> proofing, but not signal wise.
> 
> Ron W5RKN
> 
>> Date: Sun, 18 May 2008 14:28:34 -0400
>> From: Sebastian 
>> Subject: [amsat-bb]  AOP-1 Circular Polarization?
>> To: Amsat - BBs 
>> Message-ID: 
>> Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes
>>
>> Hello all, I'm getting ready to put back up my old AOP-1 antennas (the
>> old Cushcraft antennas that were popular in the days of AO-10 & 13).
>> I'm wondering whether I should follow the same procedure of cross
>> polarization for the 440 beam?  It was recommended at the time to
>> place the antenna in an X pattern instead of the cross pattern.  Also,
>> at the time, the 2 meter antenna was suggested to be placed in the
>> standard vertical/horizontal polarization.
>>
>> Please let me know which would be the best method to use for most of
>> today's birds.
>>
>> 73s de W4AS
>>
>>
>> ------------------------------
> 
> _______________________________________________
> Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb

_________________________________________________________________
Keep your kids safer online with Windows Live Family Safety.
http://www.windowslive.com/family_safety/overview.html?ocid=TXT_TAGLM_WL_Refresh_family_safety_052008