Walter Maxwell wrote:

Good response, Roy, but concerning rho and gamma to represent reflection
coefficient, I refer you to Reflections, Sec 3.1,

"Prior to the 1950s rho and sigma, and sometimes 'S' were used to represent
standing wave ratio. The symbol of choice to represent reflection coefficient
during that era was upper case gamma. However, in 1953 the American Standards
Association (now the NIST) announced in its publication ASA Y10.9-1953, that rho
is to replace gamma for reflection coefficient, with SWR to represent standing
wave ratio (for either voltage or current), and VSWR specifically for voltage
standing wave ratio. Most of academia responded to the change, but some
individuals did not. Consequently, gamma is occasionally seen representing
reflection coefficent, but only rarely."


Thanks for the information Walter. I must have a few "rare" texts that
use Gamma (Gamma to mean uppercase gamma) for the voltage reflection
coefficient.

I wonder if the recommendation / standard to which you refer is taken up
in any international standard?

I do note that my ARRL Antenna Handbook (18th edition) and ARRL Handbook
(2000) both use rho, however they reckon that rho=(Za-Zo*)/(Za+Zo)
(where Zo* means the conjugate of Zo). They do this without derivation,
and seem to be in conflict with the derivation in most texts. I suppose
the derivation is buried in some article in QST and in the members only
section of the ARRL website.

Back to notation, accepting that the preferred pronumeral for the
voltage reflection coefficient is rho, is there a pronumeral used for
abs(rho)?

Owen