[evlatests] Another wide-band test

[Bob Hayward]

The 11.6 GHz to 18.4 GHz bandwidth sounds about right. We did insertion 
loss measurements of the TTE evaluation filters with a network analyzer 
across a 10 MHz to 26.5 GHz range to measure the broadband frequency 
response as well as to determine the 3 and 30 dB attenuation points.

We also carried out and "extra wide" 11.5-18.5 GHz hot/cold load noise 
measurements on the full-up receiver.

These are the results...

Network Analyzer Sweep of 12-18 GHz Filters:
============================================

Attenuation   Frequency (GHz)
-----------   ---------------
     3 dB       11.63 - 18.30
    30 dB       11.26 - 18.62


Receiver Noise Temperature measurements:
========================================

Attenuation   Frequency (GHz)
-----------   ---------------
    10 dB        11.6 - 18.3

This "extra wide" noise measurement was on the prototype U-Band receiver 
and used rather coarse frequency steps of 100 MHz which, alas, is 
somewhat under-sampled (we now use 25 MHz steps on our standard 
12.0-18.0 GHz scans).

-Bob


Rick Perley wrote:
>     Ken set up another experiment with our full-bandwidth antennas.  
> This one is at Ku-band, using 3C84. 
> 
>     A quick perusal reveals a few issues:
> 
>     1) ea23, in RCP has a sinusoidal ripple in both amplitude and phase, 
> in baseband #1 (subbands 1 through 16).  The period of the ripple is 
> about 11 MHz. 
>     2) ea19, in LCP, as a very similar problem, in baseband #2 (subbands 
> 17 through 32). 
>     3) Some of the 'subband 0' DC offsets appear to have gone away. 
>     4) Some of the basebands are showing large steps in phase between 
> adjacent spectral windows.  The phases, after removing the delay, should 
> be continuous within a baseband, but this is commonly not the case.  
> ea13, in baseband 4 (subbands 49 through 64), in LCP, is a particularly 
> bad example. 
> 
>     Because our 8-GHz span is larger than the BW of the Ku-band 
> receivers, Ken arranged the tuning to significantly overlap the nominal 
> ends (12 and 18 GHz).  Remarkably, we are still getting good signals 
> down to 11.6 GHz, and up to 18.4 GHz. 
> 
>     The plan is to run this test again tonight, with a proper flux 
> density source. 
> 
> 
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