On Apr 16, 3:38 pm, Richard Clark wrote:
On 16 Apr 2007 14:29:01 -0700, "K7ITM" wrote:

In my mind I was qualifying it as being waves
propagating in the same direction, since the discussion centers around
propagating EM cancelling out in a finite (non-zero) volume, and as
far as I know, there hasn't been anyone suggesting that waves on a
line in opposite directions cancel over a non-zero distance.

Hi Tom,

Then the challenge devolves to a self-fulfilling proposition (which
may be your point at this turn) as it requires two sources to occupy
the same point.

Well, maybe I'm mistaken, but I was under the impression that there
was someone around here who was promoting the idea that two waves
propagating in a linear medium could cancel over some non-zero finite
volume, but not cancel everywhere along their path, even though that
path was uninterrupted by any discontinuities in the medium. Maybe
I'm mistaken, but I was under the impression that there was someone
around here who was promoting the idea that calculations based on
power rather than on voltage and current in a TEM transmission line
offered some inherent value. I posted my original, "I have yet to
see...," statements as a way of saying that I'm not convinced about
the truth of either of those ideas, and it would go a long ways toward
convincing me if someone posted examples. I'm still waiting. I still
don't have a reference that a fiber optic cable is a TEM transmission
line, though I have others that say that it's not. I still don't have
information on whether a soliton wave can propagate in a linear
medium, though I have references that say it is a non-linear
phenomenon that occurs in non-linear media. If you can convince me
that a wavefront coming to a Magic T doesn't see it as an impedance
discontinuity, we could perhaps post more about that--or not.

But so far, your responses make me think you don't disagree with my
implicit suggestions: that it's impossible to distinguish between the
condition of two cancelled waves that somehow still exist (huh?) and
the condition of no wave at all; and that there's precious little
value in doing calculations based on "forward power" and "reverse
power" in TEM lines--qualify that if you want by limiting it to the
frequency range where we find it relatively easy to express what's
going on in terms of voltage and current. That seems a reasonable
qualification in this newsgroup.

Beyond that, you're of course welcome to go off on whatever tangents
you wish. Basenote drift is the expected norm here; I engage in it
all the time myself.

And I still don't exist; I'm only a figment of Cecil's imagination.

Cheers,
Tom