[evlatests] Band Nomenclature

[Robert Hayward]

For what it's worth, here is my take on letter designations for our EVLA
receivers.

Information on microwave frequency bands can be found in such reputable
journals as Wikipedia. See...
http://en.wikipedia.org/wiki/Microwave

(Note they have a mistake in the Q-Band entry. It should be 33-50 GHz as
it is normally coupled to the frequency coverage of WR-22 waveguide.)

A more definitive list is given at the Microwave 101 website at...
http://www.microwaves101.com/encyclopedia/waveguidedimensions.cfm

A nice historical (and amusing) perspective can be found in the 1966
article "LSCX: The Microwave Alphabet Soup" which can be found at...
http://www.k5rmg.org/A-soup.html

So there is a military and commercial context behind using these letter
designations. If I call up a vendor and say a want a Ka or Q-Band Magic
Tee coupler, he will know exactly what I'm talking about.

>From a logistical point of view, it's a lot easier for those of us trying
to keep track of all our front-ends to refer to, say, Ka-Band receiver
serial number 16 as "A#16" rather than receiver "26-40GHz#16" or
"33GHz#16" or "0.9cm#16" or "9mm#16. Note that I've used the shorthand
version by dropping the K in Ka, just like we did for the VLA's Ku-Band
receivers.

As Jim alluded too, NASA's Deep Space Network uses the Ka designation, as
they do for S and X-Band as well.

Finally, we should remember that radio astronomy came of age after WWII,
not from the insight of traditional astronomers but from the hard work and
talent of a number of the engineers and physicists that had developed
radar (e.g., Hey, Lovell, Pawsey, Bolton, Kraus, etc). I can think of no
better tribute to these pioneers than by preserving their frequency band
letter legacy.

-Bob