Re: [amsat-bb] AO51 S band

[Paul Williamson <kb5mu@xxxxxxxxx>]

>Anyone know what polarisation the S band TX on AO51 is?

There's a photo of the antenna on page 7 of the Spring 2004 update 
article by W2GPS, which can be found at 
http://www.amsat.org/amsat-new/echo/OSCAR-E_Status_Report_5.pdf

 From that picture, it seems clear that the S-band downlink must be 
linearly polarized.

>I plan to run V/S mode mobile but need to build a roof mounted patch antenna
>of the correct sense.

If the downlink is linear, a circularly-polarized antenna of either 
sense will be equally fine.

With a linear (but time-varying) downlink and a circular receive 
antenna you give up a little peak performance but you get immunity 
from cross-polarization fading, which is a net win.

73  -Paul
kb5mu@amsat.org
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