"Owen" wrote in message
...
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

Hi Owen,

From the general use I'm familiar with, rho alone refers to the abs value, while
the two vertical bars on each side of rho indicates the magnitude alone.
However, following Hewlett-Packard's usage in their AP notes, in Reflections I
use a bar over rho for the absolute, and rho alone for the magnitude. However, I
explain the term in the book to avoid confusion.

Walt, W2DU