Cecil Moore wrote:


I certainly do *NOT* claim there's energy in the
canceled waves after they are canceled.

Perhaps then you'd care to describe more fully the steady state
condition wherein the canceled waves are not canceled?

ac6xg

Someone wrote:
"The energy in canceled waves is why the forward power is often greater
than the source power."

Bird says:
"Power delivered to and dissipated in a load is given by:

Wl = watts into load = Wf - Wr"

Best regards, Richard Harrison, KB5WZI

Jim Kelley wrote:

Cecil Moore wrote:
I certainly do *NOT* claim there's energy in the
canceled waves after they are canceled.

Perhaps then you'd care to describe more fully the steady state
condition wherein the canceled waves are not canceled?

Since I never said anything resembling that, you are
just up to your old semantic tricks, well known to
this newsgroup. If you still lack a conceptual grasp
of the process, please avail yourself of the flash
demo at:

http://micro.magnet.fsu.edu/primer/j...ons/index.html

Set the two waves to equal magnitudes and opposite phases.
Hint: there can be no wave cancellation without waves.
--
73, Cecil http://www.w5dxp.com

Richard Harrison wrote:
Someone wrote:
"The energy in canceled waves is why the forward power is often greater
than the source power."

Bird says:
"Power delivered to and dissipated in a load is given by:

Wl = watts into load = Wf - Wr"

The point I was trying to make is that the forward power
into a Z0-match point can be 100 watts while the forward
power out of the Z0-match point is 200 watts. In that
case, the Z0-match point is an interferometer of sorts.
An ideal non-reflective thin-film coating on glass is a
Z0-match. Hint: characteristic impedances are directly
related to indexes of refraction.
--
73, Cecil http://www.w5dxp.com

Richard Harrison wrote:

Someone wrote:
"The energy in canceled waves is why the forward power is often greater
than the source power."

Bird says:
"Power delivered to and dissipated in a load is given by:

Wl = watts into load = Wf - Wr"

Best regards, Richard Harrison, KB5WZI

Good point, Richard. Wf = Wl + Wr. Amidst all this consternation
about conserving the energy in canceled waves, we should not lose
sight of the fact that it is *reflections* (not canceled waves) which
cause forward power to measure greater than power dissipated in the
load.

ac6xg

"Jim Kelley" wrote in message
...


Cecil Moore wrote:


I certainly do *NOT* claim there's energy in the
canceled waves after they are canceled.

Perhaps then you'd care to describe more fully the steady state condition
wherein the canceled waves are not canceled?

ac6xg


now lets really have some fun with the cancelled wave and disappearing
energy crowd that redirects power from here to there and sloshes it back and
forth so it doesn't go anywhere.

This is after all an antennas group, so lets take a real antenna. I have 2
160m verticals that are 1/2 wavelength apart over a pretty darn good ground.
Now, I can feed them either in phase to get a broadside pattern, or I can
feed them 180 degrees out of phase to get an end fire pattern. Everyone
here should agree that this works as it has been well demonstrated over the
years, and even nec predicts it so art should be happy.

Now you may ask, why is this any big revelation... well, because it is a
perfect example of waves that cancel but don't disappear, slosh, or get
redirected anywhere. consider the case where the 2 verticals are fed 180
degrees out of phase. on a line 1/2 way in between them and perpendicular
to them there is perfect cancellation of the two waves... and yet, you can
move just a little bit off this line of symmetry and viola, the waves are
both there and add as expected. in fact if you walk from one vertical to
the other and keep on going on that line you will come to the center point
where the waves perfectly cancel, then keep walking and just 1/4 wave later
when you get to the next vertical, and everywhere from there on the two
waves add together.

Now how does that happen?? is there some kind of magical reflection field
set up so that no power can cross that midpoint line?? maybe this is the
first evidence of a star trek type forcefield that magically deflects
phasors while still letting you see the photons?? So where does the power
go??? at that mid point E=0, H=0, ExH must also be 0 at all time, and
everywhere along that symmetry plane... so how can the waves add up again on
the other side? quantum tunneling? art's magical levitating cosmic
diamagnetic particles??? virtual photons?? oh, I forgot, these verticals
are copper clad steel, doesn't the steel mess them up or something because
the cosmic particles fly away? or is the thin copper enough to let them
settle on an otherwise insulated slippery vertical surface??

I know what the equations say... I also know what the contest results say...
the waves keep going, and going, and going... and the qso's keep coming, and
coming, and coming. So lets see how well art's magical mystery antenna
plays in the ultimate 160m contest this weekend... how about it art, I'm
sure everyone would love to see you prove your little antenna can out play
something bigger??

Cecil Moore wrote:

Set the two waves to equal magnitudes and opposite phases.
Hint: there can be no wave cancellation without waves.

More to the point, there can be no waves under the conditions you
describe. So, again, just when do these waves actually exist, Cecil?
We apparently agree that it's not when they cancel. The only other
possibility I can think of would be when they don't cancel. So, when
don't they cancel? Does it occur in steady state?

ac6xg

Jim Kelley wrote:
Good point, Richard. Wf = Wl + Wr. Amidst all this consternation about
conserving the energy in canceled waves, we should not lose sight of the
fact that it is *reflections* (not canceled waves) which cause forward
power to measure greater than power dissipated in the load.

Now all you have to do is figure out how those reflected
waves reverse their momentum to become forward waves.
You have never offered any explanation for that phenomenon
while criticizing everyone else's explanations.
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:

Jim Kelley wrote:

Good point, Richard. Wf = Wl + Wr. Amidst all this consternation
about conserving the energy in canceled waves, we should not lose
sight of the fact that it is *reflections* (not canceled waves) which
cause forward power to measure greater than power dissipated in the load.


Now all you have to do is figure out how those reflected
waves reverse their momentum to become forward waves.
You have never offered any explanation for that phenomenon
while criticizing everyone else's explanations.

I don't criticize everyone else's explanations, Cecil. We've
discussed this countless times. It's not new or revolutionary, and
there are of course pictures of it in physics books that you can look
at. Born and Wolf has one, and so does Roller Blum, Physics Volume 2
- as I've pointed out before. You even have a similar chart
illustrating it on your web page. Obviously I didn't invent it. It's
been right there all along, just as I've told you countless times
before, and naturally it (of necessity) blends seamlessly with all of
your other favorite quotations.

In considering the transmission line matching transformer scenario (or
the antireflection coating), when we sum up all of the partial
reflections at each interface during the transient period, the sum
ultimately reaches and establishes the steady state conditions. The
sum of the reflections at each iteration show exactly how energy makes
its way from source to load.

But to follow the energy path correctly we absolutely have to approach
the problem either from the standpoint of fields or as voltages.
Power doesn't propagate. Fields do - therefore only an analysis from
that standpoint avoids pitfalls and misconceptions. If you want to
see how energy moves, then power should be calculated after a proper
voltage analysis, not in lieu of one. When approached in this manner,
it is very simple to see how energy actually does move through the
system. Note that you get the same answer in the end either way.
Both approaches obviously conserve energy. Scattering parameters and
irradiance equations are accurate shortcuts to that end. But one
should be careful not to read (or invent) too much physical science
into the shortcuts. They're mathematical shortcuts, not
phenomenological descriptions of nature.

ac6xg

Cecil Moore wrote:

[material worthy of consideration]

"Cancellation" is undeniably a misnomer. In the same way there is no
"cancellation" in a dummy load--rf simply becomes heat.

Somehow, within a coaxial tank circuit, something "appears" as
"cancellation" of waves, but they are NOT "really" canceled--canceled,
when used in the posts here has a way of SEEMING to imply that the laws
of conservation of energy are being broken--I rest assured, they are not.

In the end, the rf escapes unscathed ... I guess some of the "why" this
is occurring, you are explaining in the math you present. Have
patience, I am in the process of digesting it and brushing up on points
of my education I have seldom, if ever, used ... I have grown old and
lazy and need one h*ll of a fire built under me to move. :-D

For some this is probably childs' play, to those I say, right on! For
me, it has become as difficult as when I had to "wrap" my mind around
binary trees--just when I was I ready to give up and change majors--I
had my revelation! (indeed, I think of it as a, "Revelation Onto John"
;-) )

Regards,
JS