A couple of typos fixed:

Cecil Moore wrote in news:0svUh.417$Yo2.402
@newssvr19.news.prodigy.net:

Now let's look at the powers in accordance with HP's
Ap Note 95-1. For that, we don't need to know the Z0.
The beauty of an S-Parameter analysis is that if one
squares the normalized voltages, one gets power.

Cecil,

AN95-1 is a slide show, it is a presentation to accompany a talk, and as
such is incomplete.

Another HP note is AN154 which is derived from a training seminar, but is
more complete in its development. Chapter 1 is relevant to your use of S
parameters.


Let me quote:

Notice that the square of the magnitude of these
new variables has the dimension of power. |a1|^2
can then be thought of as the incident power on
port one; |b1|^2 as power reflected from port one.
These new waves can be called traveling power
waves rather than traveling voltage waves.
Throughout this seminar, we will simply refer to
these waves as traveling waves.

It is a leap to move from "can be thought of as power" or "has the
dimension of power" to your statement (which you attribute to HP AN95-1)
"The beauty of an S-Parameter analysis is that if one squares the
normalized voltages, one gets power." Did AN95-1 state clearly that which
you suggest?

Nowhere in Chapter 1 of AN154 do they perform alegebraic operations on
power, the chapter is full of expressions, but they do not use |Sxx*ax|^
2.


|s21(a1)|^2 = 50 watts

|s22(a2)|^2 = 50 watts

|b2|^2 = 200 watts

Even in the S-Parameter analysis, superposing two 50W
waves in phase yields 200 watts. Constructive interference
not only makes it possible but demands it.

So now you are superposing power to "yield" a resultant power. Did HP
show you how to do that, or is it all your own work?

Owen