Gene Fuller wrote:
Where are the equations that describe this "delta-t" stuff that you keep
bringing up?

delta-t is a mathematical term, Gene, related in the limit
to the differential dt. If you have to ask, I'm sure you
wouldn't understand the explanation.

Given the following experiment with two signal generators
equipped with circulators and load resistors - the generators
are phased-locked to ensure coherency:

100W 50W
50 ohm---50 ohm line---+---291.4 ohm line---291.4 ohm
SGCL1 SGCL2

Here's the setup for determining s11 and s21 with
SGCL2 turned off.

100W
50 ohm---50 ohm line---+---291.4 ohm line---291.4 ohm load
SGCL1

Here are the results:

a1----|
|----s21(a1)
s11(a1)----|

THE EM WAVE, s11(a1), EXISTS, IS MEASURABLE, AND IS ALIVE
AND WELL.

Here's the setup for determining s12 and s22 with
SGCL1 turned off.

50W
50 ohm load---50 ohm line---+---291.4 ohm line---291.4 ohm
SGCL2

Here are the results:

|----s22(a2)
s12(a2)----|
|----a2

THE EM WAVE, s12(a2), EXISTS, IS MEASURABLE, AND IS ALIVE
AND WELL.

Now power off both signal generators and power them up
simultaneously. Let t=0 be the time when s11(a1) and
s12(a2) first exist. Superpose s11(a1) and s12(a2). How
long does it take to achieve b1 = s11(a1) + s12(a2) = 0?
I estimate that time to be delta-t which becomes dt
in the differential equation limit.

The principle of superposition allows us to observe that
s11(a1) and a12(a2) actually existed before they were
canceled.
--
73, Cecil http://www.w5dxp.com