It's true that even a simple DC battery circuit can be described in
terms of incident and reflected power, SWR, and reflection
coefficients, but that's very unrealistic when trying to conceptually
understand what's going on.

I suppose a point that I'm making is that understanding how to match a
source with a load doesn't have much to do with reflections and
standing waves although, again, it can certainly be described
(unrealistically) that way.

Take the case of a transmitter and an antenna connected together with
a two-port black box between them, and that black box happened to
contain a transmission line. That unseen transmission line has
standing waves and reflections (assuming a mismatched condition),
losses, etc. all contained within the box. However, the transmitter
only sees a steady state complex impedance when looking into the box
(at a single frequency). Obviously there's some conjugate matching
that needs to take place for maximum power transfer, but there are no
reflections or standing waves involved outside the box -- unless
transmission line stubs are used for matching.

In short, transmission lines have reflections and standing waves, and
as a "black box" they affect how the load is seen by the source. But
extending the power reflection concept outside of that black box only
confuses things, even though it works mathmatically.

Al

Cecil Moore wrote in message ...
alhearn wrote:
Herein lies one of the big problems with the "reflection" definition,
conceptually.

That's why I often resort to a signal generator with a circulator/load
to illustrate my point. That signal generator *is* a constant power
source.

Therefore, what is commonly called "reflected power" is power that
never leaves the transmitter and is dissipated as heat by the
transmitter's internal 50 ohm impedance (if the transmitter's design
doesn't prematurely shut down first).

You can mount an argument that if the source doesn't see its
source impedance, then there is a reflection at that internal
mismatch. But that's not what is commonly called reflected power.

When we talk about reflected power on this newsgroup, we are usually
referring to the forward power rejected by a mismatch between the
transmission line Z0 and the antenna impedance (associated with mismatch
loss). In a typical ham radio antenna system, the "lost" reflected power
is forced to engage in destructive interference at the tuner and thus
joins the forward power wave.