Cecil Moore wrote:
Jim Lux wrote:

Cecil Moore wrote:

"In some professional literature, Gamma is used in place of rho
to represent the reflection coefficient."


I would say in *most* professional literature...


The above quote from the ARRL Antenna Book is from
the 1988 edition.

Hmm.. yes, well fashion does change in the professional literature over
time, and your citation is almost 20 years old. However, while cleaning
out a lab downstairs at work, I ran across a reprint of:
Kerns, David M., "Definitions of v,i, Z, Y, a, b, Gamma, and S", Proc.
IEEE, v55 n6, June 1967, pp892-900

no rhos to be found.

In another useful paper, Dybdal,R.B., Ott,R.H., "Coherent RF Error
Statistics", IEEE Trans MTT, vMTT-34,n12, Dec 86
(anyone doing precision measurements on RF systems with mismatches
should read this paper, if you want to get a handle on measurement
uncertainties..)
Gamma is used for the reflection coefficient, and rho is used for, of
all things, the phase of the reflection.

That's not to say that there's not a paper around from the 70s that uses
rho.. and certainly, if you go back to the 30s and 40s, one might find
rho (as a magnitude of the reflection coefficient) more commonly used,
reflecting (no pun intended) the use of instruments that didn't measure
phase. Precision phase measurement of reflections is a relatively
recent (last 30 years?) phenomena..

So, I'll revise and say in *most current* professional literature...