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@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Clint Bradford Sent: Sunday, December 06, 2009 7:15 PM To: Glenn AA5PK Cc: amsat-bb@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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