[evlatests] Phase Hopping Antennas

[Rick Perley]

    It has been recently reported that some antennas are hopping phase 
upon change of source (and not necessarily when the band is changed). 

    The 'switch stress test' provides an opportunity to look for this.  
To remove atmospheric effects, I differenced the phases from IFs 1 and 
2, for each of RCP and LCP.  The results are quite striking:

    There are three antennas which display frequent bad hopping. 

    1) Antenna 22 at all bands. 
    2) Antenna 13 at all bands *except* X and K.
    3) Antenna 12 at all bands *except* X
   
    In addition, antenna 7 hops at most bands, but only did so on one or 
two scans. 
    Antenna 9 and 11 also showed an occasional hop.