[amsat-bb] Re: AO-51 - After the Change

[Art McBride]

Clint,
Rotating a linear polarized Yagi in a circularly polarized field should
result in less than a few dB of change, no change if the circular antenna is
perfectly circularly polarized. When using a linear antenna ground effects
including reflections will cause a larger change. Using circular on both
ends will result in less fading from the ground effects and no change in
signal for antenna rotation on the S/C side providing the S/C antenna has a
good pointing angle. Losses of 22 +dB are reserved for cross polarization of
antennas H-V and LH to RH.

Art, KC6UQH 

-----Original Message-----
From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
Behalf Of Clint Bradford
Sent: Sunday, December 06, 2009 7:15 PM
To: Glenn AA5PK
Cc: amsat-bb at amsat.org
Subject: [amsat-bb] Re: AO-51 - After the Change

 >> ... I think the handheld ops have less trouble with the polarity  
switching because tend to compensate more quickly with a twist of the  
wrist ...

That phenomenon is not evident now - nor has it ever been - for me on  
AO-51.

I know the engineers say I am supposed to be increasing or decreasing  
my signal strength by 22 or 23db by merely twisting my Yagi 90  
degrees. But I have hundreds of witnesses during dozens of  
demonstrations who will tell you that when the Yagi is turned 90  
degrees, there's no discernible change in the signal.

This is not a scientific approach to the subject, of course. Just what  
my aging ears can hear.

I have heard fellow AMSAT members describe AO-51's "signal fading due  
to the satellite tumbling in space," too. I am not using elaborate  
equipment, but have no idea what they are talking about.

Just my firsthand observations. Guess I could be wrong ... we are a  
little different - I am told - out hre on the West Coast of the US.

Clint Bradford, K6LCS




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