Tam/WB2TT wrote:
"Cecil Moore" wrote in message
It does that by not allowing reflected energy to
reach the transmitter and redistributing the
reflected energy back toward the antenna as
part of the forward wave. Thus a transmitter can
be sourcing 100 watts while the forward power
on the transmission line is 200 watts.

What it really is is an impedance matching network. You adjust the antenna
tuner so that the transmitter sees 50 Ohms. If your SWR meter is calibrated
for 50 Ohms, that means an SWR of 1:1 (between the tuner and the radio).

Yes, and that is a Z0-match to 50 ohms. What happens
at a Z0-match is wave cancellation of reflected waves
through destructive interference which redistributes
the reflected energy back toward the antenna in the
form of constructive interference energy that joins
the forward wave.

micro.magnet.fsu.edu/primer/java/scienceopticsu/interference/waveinteractions/index.html

"... when two waves of equal amplitude and wavelength that are
180-degrees ... out of phase with each other meet, they are not actually
annihilated, ... All of the photon energy present in these waves must
somehow be recovered or redistributed in a new direction, according to
the law of energy conservation ... Instead, upon meeting, the photons
are redistributed to regions that permit constructive interference, so
the effect should be considered as a redistribution of light waves and
photon energy rather than the spontaneous construction or destruction of
light."

The reason that the transmitter is protected is that
the Z0-match *causes* that redistribution of the reflected
energy back toward the antenna. Protecting the transmitter
is a side-effect of tuning the entire antenna *system*
to resonance.
--
73, Cecil http://www.w5dxp.com