[evlatests] Spectacular Ku-band Sensitivity Results

[Rick Perley]

    Bob Hayward and I have spent the last two days on antenna 24, 
measuring the performance of the prototype Ku-band (12 -- 18 GHz) 
receiver.  A full report will follow in a few days in the form of an 
EVLA memo.  But the results are so good that I thought a quick 
communication via this channel might be useful. 

    The usual suite of measurements were made, using the 'gold standard' 
power meter.  Measurements were made in a 200 MHz-wide window centered 
at 11.6, 12.2, 13.2, 13.8, 14.9, 15.9, 16.9, 18.0 and 18.5 GHz.  Note 
that the first and last are well outside the defined band. 

    Essential results for Tsys and Trec are given below.

Freq        Tsys         Trec
---------------------------------
11656      41.1         23.1
12168      32.5         14.7
13192      28.0         10.4
13832      25.0           5.7
14856      25.8           5.3
15880      28.8           8.6
16944      28.3          10.7
17968      32.9          15.2
18480      132           114
------------------------------------

The values of Trec (and Tcal) match the lab results very well. 

Spillover and antenna efficiency data were taken, but are not yet 
reduced.  It is clear however that the efficiency will be close to the 
expected values -- about 0.5. 

The Tsys values easily beat the Project Book requirements.  Kudos to Bob 
Hayward and the FE group for putting together such a fine system. 

We return to the site today to perform similar tests on the wide-band L 
and S band systems.  Results will be distributed when ready.