[evlatests] What does water do?

[Rick Perley]

Water in the feeds causes a lot of problems.  Very strongly affected is 
the polarization.

Attached here are two plots -- showing the antenna cross-polarization 
for a 'dry' antenna (ea01) and a 'wet' antenna (ea05).

Each shows the cross-polarization phase (narrow plots) and amplitude 
(wider plots).  Phase units are +/- 180 degrees. Amplitude units are 0 
to 20% (actually, in tens of percent). These data were taken July 17.  
Rob informs me that ea05 has been dried out since then.

ea01 shows the expected behavior -- fairly flat, some ripples, 
amplitudes less than 8%.

ea05 is 'rather different'.

Similar behavior to ea05 -- but not nearly so extreme -- is seen in 
ea11, ea18, and ea21.

Rick
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