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

Cecil Moore wrote:
Tam/WB2TT wrote:

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.

Correct, except for the part about destructive interference
redistributing reflected energy. Please note the absence of any such
claim in the cited (or any other) reference.

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."

One addendum:
"Therefore, simple diagrams, such as the one illustrated in Figure 1,
should only be considered as tools that assist with the calculation of
light energy traveling in a specific direction."

The same holds true for the simplified explanation provided by the site.

The reason that the transmitter is protected is that
the Z0-match *causes* that redistribution of the reflected
energy back toward the antenna.

More to the point, the Z-match reflects energy back toward the antenna.

73, ac6xg

Jim Kelley wrote:
Correct, except for the part about destructive interference
redistributing reflected energy. Please note the absence of any such
claim in the cited (or any other) reference.

Please note the presence of constructive interference in
the cited reference: "... the photons are redistributed to
regions that permit constructive interference ...", which
implies an equal magnitude of destructive interference
elsewhere in order to avoid violating the conservation of
energy principle. It is akin to the gain of an antenna.
Constructive interference in one direction is matched
by an equal magnitude of destructive interference in
another direction.

More to the point, the Z-match reflects energy back toward the antenna.

Yes, as "constructive interference" energy which requires
destructive interference elsewhere to balance the
energy equation. Since there are only two directions
available in a transmission line, any constructive
interference toward the load must be balanced by an
equal magnitude of destructive interference toward the
source.

Quoting Reflections II, by Walter Maxwell, page 4-3:
"The destructive wave interference between these two
complementary waves causes a complete cancellation of
energy flow in the direction toward the generator.
Conversely, the constructive wave interference produces
an energy maximum in the direction toward the load,
resulting from the sum of the two reflected waves
and the source wave."

For a non-reflective thin film coating, these two
reflected waves are known as the internal reflection
and the external reflection.
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:
Jim Kelley wrote:

Correct, except for the part about destructive interference
redistributing reflected energy. Please note the absence of any such
claim in the cited (or any other) reference.


Please note the presence of constructive interference in
the cited reference: "... the photons are redistributed to
regions that permit constructive interference ...", which
implies an equal magnitude of destructive interference
elsewhere in order to avoid violating the conservation of
energy principle. It is akin to the gain of an antenna.
Constructive interference in one direction is matched
by an equal magnitude of destructive interference in
another direction.

More to the point, the Z-match reflects energy back toward the antenna.


Yes, as "constructive interference" energy which requires
destructive interference elsewhere to balance the
energy equation. Since there are only two directions
available in a transmission line, any constructive
interference toward the load must be balanced by an
equal magnitude of destructive interference toward the
source.

Quoting Reflections II, by Walter Maxwell, page 4-3:
"The destructive wave interference between these two
complementary waves causes a complete cancellation of
energy flow in the direction toward the generator.
Conversely, the constructive wave interference produces
an energy maximum in the direction toward the load,
resulting from the sum of the two reflected waves
and the source wave."

For a non-reflective thin film coating, these two
reflected waves are known as the internal reflection
and the external reflection.

Physical objects redistribute energy. Interference simply describes
its spacial distribution.

73, ac6xg

Jim Kelley wrote:
Physical objects redistribute energy.

If you consider a Z01 to Z02 impedance discontinuity
to be a "physical object" then I agree.

Interference simply describes its spacial distribution.

Interference, the noun event, is somewhere in the chain
of *events* between the reflections caused by the impedance
discontinuity and the spacial (re)distribution of energy.
Interference, the noun event, is a subset of superposition,
i.e. not all superposition results in interference.

Interference, the adjective, as in the "interference pattern",
describes the results of interference, the noun event. The
interference pattern describes the spacial distribution.

Maybe your answer to the following question will shed
some light on what you think is our disagreement.

In the RF fields in free space surrounding a dipole,
exactly where are the physical objects that redistribute
the energy? As I understand it, each segment is considered
to be a unit radiator and the radiation interference pattern
is the calculated result of the interference events in free
space in the far field.
--
73, Cecil http://www.w5dxp.com