[evlatests] P-band Status (observational)

[Rick Perley]

    Another test was run last night.  The data (with few exceptions) are 
of superb quality. 

    Here are the issues found:

    0)  Zero fringes (i.e., only noise is seen): 

      ea17 on both polarizations

    1) Weak fringes.  The following are low by the factors given (power 
units):

    ea09R:     50
    ea11R:       4
    ea24R        4
    ea04L:       4

    2) Zero switched power:      (no change here)
   
     ea10, 11, 13 and 25

    3) Weak switched power (low by a factor of 10 or more from the normal)

    ea02L, and ea18L

    4) Weird Bandpass Shapes:

    ea07R     There is a very strong 4 MHz ripple, seen in both 
amplitude and phase.  About 5 dB (in power) from peak to peak.  This 
looks like a standing wave, except that the physical length suggested is 
37 meters -- longer than any scale on the antenna! 

    ea10L     A 4.5 MHz ripple, not nearly as strong as in ea07R.  
Length would be 33 meters ...

    ea25R     Same as in ea07R, of the same strength. 

    General comment:  This small-scale ripple is seen on nearly all 
antennas and in both polarizations.  Except for the antennas noted 
above, it has a pk-pk variation of about 0.1 dB of less. 

    5)    Reversed-Polarized antennas:

    None!

    6)  High Polarization Leakage:

    ea05, ea24, and ea26 all show 25% or more leakage into the 
cross-hand correlations.  Note that ea05 and ea26 have an identical 
frame -- the cross-hand correlations between these two have nearly zero 
cross-polarization. 
    Somebody should first check if these three antennas have dipoles 
which are way out of alignment (rotated w.r.t the antenna quad legs).