On Sat, 05 Apr 2008 14:56:35 -0500
Cecil Moore wrote:

Roger Sparks wrote:
We have to have a starting point, which must be the source power. How could we avoid having a starting point?

We are analyzing a resistor isolated from the source and load
by 1WL of ideal feedline on each side. All we need are the
steady-state values of Pfor1, Pref1, Pfor2, and Pref2. It's
much like an s-parameter analysis of a 4-terminal box with
a 50 ohm series resistor. If we know a1 (Vfor1) and a2 (Vref2),
that is all that needs to be known to complete the analysis.
We don't actually need to know anything about the source and
the load if a1 and a2 are given.

I think this equation is missing some terms, reflections 2,3,4...n.

The equation already contains all of those "missing'
terms because it is steady-state and all of those
terms have already been added in to the total.
--
73, Cecil http://www.w5dxp.com

From your previous posting, you gave the equation

Pfor1 + Pref2 + P.Rs = Pfor2 + Pref1 (all average)

Where Pfor1 and Pref2 were toward the resistor, and Pfor2 and Pref1 were away from the resistor. This equation seems to assume that the power to the resistor is zero. This is because the same current must flow in Pfor1 and Pfor2, and the same current in Pref2 and Pref1. The voltage drop through the resistor only happens when the circuit is complete on both sides of the resistor.

If we try to separate them as you are suggesting, we would have to recognize that it is also correct to say that

Pfor1 + Pref2 = Pfor2 + Pref1 + P.Rs (all average)

This is true because power only flows when the circuit is complete, and we can not say all the power comes from the left, or from the right. The power only flows when both are connected so the power must come from both sides.

There will never be one answer for your equation, unless, as you suggest, a1 and a2 are given.

--
73, Roger, W7WKB