On Fri, 17 Jun 2005 22:44:13 -0400, "Walter Maxwell"
wrote:

[snip]


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.

Confusion reigns.

Four years ago in another thread I posted thus:

Quote

On Mon, 12 Feb 2001 15:25:28 -0800, Roy Lewallen
wrote:

Just a point of clarification. Rho in these equations is the magnitude
of the reflection coefficient, not the reflection coefficient itself.
The reflection coefficient is actually a complex number. Rho is
unfortunately used to sometimes represent the (complex) reflection
coefficient and sometimes (like here) its magnitude, although some
people (me included) prefer to use uppercase gamma for the complex
reflection coefficient and lowercase rho for its magnitude.

Roy raises a good point. Tom Bruhns already took me to task for a
somewhat careless use of rho. Although I did define it below, as Roy
and Tom said, it is often used as a complex number.

I too prefer upper case Gamma for the complex number and rho for the
magnitude but unfortunately the literature is full of confusing usage.
Some of the literature was even published by Tom's employer, the
former H-P, now Agilent (how do you pronounce that again?)

My autographed copy of Steve Adam's, book "Microwave Theory and
Applications", published by H-P, shows on page 23:

" |Gamma| = rho "

Similarly, my handy dandy H-P "Reflectometer calculator" sliderule
says that SWR = (1 + rho) / (1- rho) which bears a striking
resemblence to what I wrote below.

But then in H-P's App Note 77-3, "Measurement of Complex Impedance
1-1000 MHZ", it says that rho is a vector quantity and it shows:

SWR = (1 +|rho| ) / (1 - |rho| )

Finally, the best reference I have is General Radio's "Handbook of
Microwave Measurements" (out of print but reissued by Gilbert
Engineering) and it says that Gamma is complex and rho isn't.

End quote.