[evlatests] More Good News about Ku-Band

[Rick Perley]

    I've reduced all the calibration data taken last Thursday. 

    System temperatures are unchanged from my previous report. 

    Efficiencies were measured through on/off measurements of Jupiter.  
Using Bryan's model estimates on the thermal emission, and including the 
(small, but notable) non-thermal component, efficiencies are found to be 
in the low-to-mid 60s (percent, that is) at the low half of the band, 
and about 60% in the upper half.  These are reasonable values.  A 
notable exception (which bears a repeat observation) is 54% at 14856 MHz 
-- right in the middle of the band.  No obvious error in the data can be 
found which might explain the discrepancy. 

    From the tips we can derive the opacities and spillover, using the 
elevation range of 20 through 40 degrees (the justification for this 
will be in the upcoming memo).  Zenith opacities are 0.014, which is 
quite reasonable.  The spillover contribution is 13 to 15 K.  (In 
essence, this represents the power seen which is not from the receiver, 
the 3K BB, or the atmosphere). 

    As noted at all other bands, the spillover is not at all constant 
with elevation.  There is an excess (above the base levels given above) 
at high elevations of about 1.5K.  At low elevations, there is a 
remarkable additional spillover, rising from 0 to about 2.5K as the 
elevation declines from 20 to 10 degrees.  This additional spillover 
then declines to the 'base level' as the elevation decreases from 10 to 
8 degrees.  This is the same behavior as seen at K-band -- but not at Ka 
or Q bands.   No simple model (that I can think of) can account for this. 

    Details and plots will be shown on Thursday. 

    The overall performance of this receiver is simply outstanding.