This topic has been discussed in this newsgroup several times in the
past. In my posting of June 17, 2005 in the thread " Calculating VSWR
from rho and rho from VSWR" you'll find a summary of what I found in use
by authors of 16 different textbooks. As you'll see, if you look it up
at http://groups.google.com, there's no single standard usage.

Personally, my preference is the same as Wes' and Owen's - Gamma for
complex reflection coefficient, rho for its magnitude. But usage is so
varied that it's necessary to explicitly show what the symbols mean
unless it's obvious from the context.

Roy Lewallen, W7EL

Owen Duffy wrote:
"Wes" wrote in news:1176385196.714553.293960
@y5g2000hsa.googlegroups.com:

The ARRL Antenna Book implies that rho is used
by amateur radio operators while Gamma is still
used in some professional circles.
--
As far as I'm concerned, Gamma is the complex reflection coefficient;
rho is its magnitude.

Hi Wes,

My preferred usage is the same, and for the reason that Gamma and rho can
be written directly in html as the greek symbols, and in ascii text as
Gamma and rho. The notation that rho is the magnitude of the complex
reflection coefficient and that the complex reflection coefficient is
written as rho with a bar over it is not conveniently and consistently
expressed in a short notation in ascii only media.

If it is declared (as I did in my post) then the usage is fair. The
sidetrack onto "standard" notation was just another diversionary tactic
from YKW.

Owen

Glossary:
YKW - You Know Who