[mmaimcal] reference

[Bryan Butler]

the reference that al asked me to send around for the aperture
averaging analysis is:
R.P. Linfield, Effect of aperture averaging upon tropospheric phase
 fluctuations seen with a radio antenna, Radio Science, v.33, 1353-1359, 1998

there are a few older papers on this subject which i dug out when
the antenna diameter issue was raised again recently:
Karasawa et al., IEEE AP-36, p.1608, 1988
Haddon & Vilar, IEEE AP-34, p.646, 1986
Tamir et al., Appl. Opt., 23, p.2359, 1984

note that there are 2 other articles in the sept-oct Radio Science issue
which are of interest - one on the japanese paired antenna calibration
tests, another on 20-32 GHz atmospheric modelling...

	-bryan