[evlatests] L-Band sensitivity below 1400 MHz

[rperley at nrao.edu]

Bob Hayward and I spent most of yesterday doing the usual suite of tests
at L-band on antenna 24, which is equipped with the wideband OMTs.  Our
previous Lband results (written up in various EVLA Memos) were done with
the old-style polarizers, which prevented relevant measurement at
frequencies below 1300 MHz.

Our new measurements show the full range and capabilities of the EVLA
L-Band design.  I give below Tsys at el=90, Tsys at el = 8,and the antenna
efficiency, for a few frequencies.

Freq.  T90    T8    Effic.
---------------------------
1400    29    44      .43
1150    38    50      .45
1100    40    54      .47
1050    38    52      .46
1000    50    64      .44
 950    68    83      .39

Performance rapidly degrades below 950 MHz.  Performance between 1300 and
1900 is fairly constant.

A full memo will be distributed shortly.