On Sun, 09 Apr 2006 23:42:56 GMT, Owen Duffy wrote:

On Sun, 09 Apr 2006 16:35:30 -0700, Wes Stewart
wrote:

On Sun, 09 Apr 2006 21:09:07 GMT, "Tom Donaly"
wrote:

Peter O. Brackett wrote:

Gamma Fans:

One area of practical interest for which Zo is not "real" occurs over
[broad] ranges is in the area of application of the so-called "last mile"
[for you Newbies that might be "first mile" (grin)] of POTS (Plain Old
Telephone Service) twisted pair transmission lines to a variety of
communications "last mile" communications systems.

Over the frequency ranges of interest for telephone cable applications i.e.
from below 25Hz or so for some signalling and on up to several hundred kHz
or even a few MHz for xDSL applications such as ISDN BA and HDSL, T1,
etc..., the telephone twisted pair exhibits a Zo that varies all over the
map!

In this arena, complex Zo and highly variable Gamma is the norm, in this
twisted pair media and for those kinds of applications, unfortunately for
Mr. Smith Zo is NOT purely resistive.

Aren't you supposed to normalize the chart to Zo? Nothing Mr. Smith
said required Zo to be resistive.


But most of the charts don't scale the area where the magnitude of the
reflection coefficient is greater than 1.

Most don't, but some do. [g]