Richard Harrison wrote:

Tor, N4OGW wrote:
"You CANNOT superimpose POWERS, or even talk about the "power" of
various reflections in the same media."

It is done all the time. P=Esquared / R = Isquared x R.


On page 99 of the 1955 edition of "Electronic and Radio Engineering"
Terman writes:

"The standing-wave ratio S is one means of expressing the magnitude of
the reflectiom coefficient; the exact relation between the two is:

S=1+absolute value of the reflection coefficient / 1-absolute value of
the reflection coefficient

or

absolute value of the reflection coefficient= S-1/S+1

Standing-wave ratio=S=Emax/Emin

This definition of standing-wave ratio is sometimes called voltage
standing-wave ratio (VSWR) to distinguish it from the standing-wave
ratio expressed as a power ratio, which is (Emax/Emin)squared."

I think he means that it does not occur in nature, and it therefore
shouldn't be done mathematically. That's because power doesn't
propagate, and
I hasten to add - neither do Poynting vectors. Nor does power reflect,
refract, or diffract. Power is a rate at which energy is transferred,
absorbed, or dissipated. It's not a wave which propagates. It's a
mathematical product of two of the characteristics of a wave that
propagates. Numbers on the other hand can indeed be multiplied, divided,
squared, added, and subtracted. We can often even get the right answer
when we do that with power numbers. But that fact can't necessarily be
extrapolated to mean that the given mathematical operation also takes
place in a transmission line. An that is what the author in question
is attempting to have us believe.

73, ac6xg