[evlatests] Antenna 21 at P-band

[Rick Perley]

I wrote earlier noting that the power gain of ea21 in the Vertical polarization was low by a factor of about ten.

It isn't always like this.  Over the past two nights, we've had 9 short (40 minute) observations of a strong calibrator.  For all antennas except ea21V, the gains are wonderfully stable, and nearly the same between all antennas.  Just what we like to see.

For ea21, the 'H' polarization is like the other antennas.  But the 'V' polarization is very different:

For 6 of the 9 observations, the correlated power is about a factor of ten low.  For the other three observations, it's close to the other antennas.  But, for one of these, the antenna gain changed from a 'good' state to the 'bad' state steadily over an ~8-minute duration.

Very strange behavior.

Sadly, ea21 is on pad E72, making it hard to get to ...

Does anybody have an idea of what is wrong here?

Rick


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