[evlatests] Antenna 22 polarization at X-band ...

[Bob Hayward]

Except this is an old X-Band receiver with a Septum Polarizer. This is 
not a typical failure mode.

If it was a C-Band receiver, say, with a bad connection on one of the 
linear polarization output from OMT to the 90 deg hybrid coupler, it 
would make sense (i.e., degrades the Trx by a factor of 2 and makes it 
linear polarized). So I'm puzzled...

We should probably drop the receiver to see if there is any debris on 
the vacuum window (such as metal shards from the feed).

-Bob


Ken Sowinski wrote:
> On Thu, 23 Dec 2010, Rick Perley wrote:
> 
>>    In calibrating the X-band 'Hercules A' demo project data, (taken
>> last week) I find that antenna 22 is 100% polarized!  This invariably
>> means that only one of the two linearly polarized outputs from the OMT
>> is actually being used ...  A cable is disconnected?
> 
> This is surely the explanation for the poor amplitude
> eresponse from ea22 at X band that we have noticed for
> many weeks.
> 
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