Jim Kelley wrote:

Cecil Moore wrote:
rearward-traveling momentum energy in those two waves is conserved by
changing direction to become part of a forward-traveling wave.

Yeeesh. You had it on, dog, up until that. And don't try to tell me
(again) that I'm lying that you said it.

(Remember when you wrote this? "If reflected energy makes its way back
into the final amp, it was never generated in the first place, by
definition." Hint: apply the same idea to your "rearward-traveling
momentum" and you'll have it.)

Egads Jim, exactly how much of reality do you think I am capable of
ignoring? Obviously, not as much as you. Why not just say, "God is
the cause of everything I (Jim) cannot explain or understand."?
The meaning would be virtually identical to your present positions.

I *don't* agree with that definition above and your implication that
momentum and energy don't need to be conserved is simply metaphysics
in action. You can argue against energy conservation all you want.
*Conservation of Momentum* has got you over a barrel in this argument
whether you realize it or not. Somehow, the momentum in the wave
reflected from a mismatched load is reversed. Please explain how
that happens without changing directions. Somehow, the energy in
the wave reflected from a mismatched load changes directions. Please
enlighten us on exactly the mechanism involved. Hint: J.C.Slater
explained it all in _Microwave_Transmissions_ before you were born.
--
73, Cecil http://www.qsl.net/w5dxp



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On Mon, 24 May 2004 13:19:41 -0500, Cecil Moore
wrote:
Well Richard, here's your chance. Please enlighten us on J.C.
What was the original question? [accredited stock response]

Dave wrote:
of course it is against guidelines. you were starting a new thread without
changing the subject. in effect hijacking the thread for your own
discussion.

Of course, it is not against the guidelines as the subject was "Reflected
Power". I simply continued to talk about reflected power, the subject of
the thread. That's a broad subject. Perhaps the originator erred in choosing
that broad of a subject but he chose that subject nevertheless. All of my
postings to this thread have been about reflected power, including this one,
in defense of my postings about reflected power.

i said it was real world, but it is not what the original thread was about.

The original thread was about "Reflected Power". My example was about
reflected power. I might not even have read the text of the original
posting. It would be interesting to know why your agenda requires
diverting the issue away from "reflected power"? What are you afraid of?
--
73, Cecil http://www.qsl.net/w5dxp



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Tam/WB2TT wrote:

"Cecil Moore" wrote:
Richard, you know you are going against the conventional wisdom on
this newsgroup. Ghosting cannot exist during steady-state so if
ghosting exists it simply means that you are still in the transient
state and the steady-state doesn't exist (yet).

Looking for the smiley face.

Is there a smiley face that means, "sad but true"? Many otherwise
intelligent, knowledgeable, educated engineers have attempted to force
their metaphysical "steady-state" agenda on uninitiated and unsuspecting
victims. One is saddened by such an event and one wonders why. Does
a steady-state religion or creed exist within amateur radio? If so,
what are its purpose and goals?
--
73, Cecil http://www.qsl.net/w5dxp



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Jim Kelley wrote:
We both know that momentum and energy must be conserved. We just
disagree agree on how nature chooses to do that.

Well then, please enlighten us, Jim. How does nature choose to
reverse the momentum in the wave reflected from a mismatched
source? It is obvious that the wave reflected from a mismatched
source has momentum in the rearward direction. Exactly what
reverses that momentum? Please be specific. Remember that standing
waves prove that the rearward-traveling wave exists in reality and
thus possesses energy and momentum in the rearward direction, both
of which must be conserved.

Maybe you should read _Microwave_Transmission_ by J. C. Slater
before you continue?
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil Moore quote below & 'steady state'

The transmitter is continuously generating incident power, which is
continuously subject to reflection(s) by any mismatch in the antenna system.
Given the right magnitude, phase and time displacement, each reflection will
produce a continuous ghost on the TV screen.

These ghosts can be seen (continuously) in/on the output waveform of a TV
demodulator connected at the output of the transmitter -- both in time
domain on an oscilloscope, and visually on a monitor. I've seen these
continuous reflections scores of times at TV tx sites all over the US as a
field engineer for RCA Broadcast Division.

"Conventional wisdom" on this NG may say otherwise, but hopefully some may
learn the reality from this exchange.

- RF
____________________

"Cecil Moore" wrote in message
...
Richard Fry wrote:

TV Ghosting (quotes below)

To elaborate, the visibility of a ghost image in analog TV systems is
related to the magnitude, phase and time displacement of the RF
reflection
that produced it as compared to the original, or non-reflected waveform.

The round-trip transit time from the TV tx output to the mismatch in its
antenna system will determine the time displacement of the ghost, at the
rate of 1 microsecond of displacement per ~490 feet of distance between
the
tx and the reflection plane (vp = 0.997c).

Richard, you know you are going against the conventional wisdom on
this newsgroup. Ghosting cannot exist during steady-state so if
ghosting exists it simply means that you are still in the transient
state and the steady-state doesn't exist (yet).

Richard Clark wrote:

wrote:
Well Richard, here's your chance. Please enlighten us on J.C.

What was the original question? [accredited stock response]

When totally ignorant, divert the issue as long as possible.
Why am I not surprised?
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil Moore wrote:
Well then, please enlighten us, Jim. How does nature choose to
reverse the momentum in the wave reflected from a mismatched
source? It is obvious that the wave reflected from a mismatched
source has momentum in the rearward direction.

Typo: please change "source" to "load" in the above. Sorry.



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On Mon, 24 May 2004 14:06:28 -0500, Cecil Moore
wrote:
What was the original question? [accredited stock response]
When totally ignorant, divert the issue as long as possible.
Why am I not surprised?
Are you sure this is the original question? [accredited stock
response]

Henry Kolesnik wrote:

I know that any power not dissipated by an antenna is reflected back to the
transmitter. Then the transmitter "reflects" this reflection back to
antenna, ad nauseum until its all gone. I also know that a short or an open
is required to reflect power and I'm searching for which it is, an open or a
short. I'm inclined to think it's a virtual open but I'm at a loss to
understand that and I wonder if someone has a good explanation or analogy
and some math wouldn't hurt.
tnx
Hank WD5JFR

Hi Hank,

Here's a link which talks about (and illustrates) the physics of waves
at a boundary.

http://www.physicsclassroom.com/Class/waves/U10L3a.html

It shows what happens at the two extremes for transverse waves along a
string - not unlike electromagnetic waves in a transmission line in some
ways. In one instance, the string is fastened directly to the boundary
- a rod in this case. This is analogous to a short across a
transmission line. It will be seen that a reflection occurs, and that
the wave becomes inverted upon reflecting.

In the other case, the string is fastened to a ring which can slide
freely up and down the rod. This case is analogous to an unterminated,
or open transmission line. It can be seen that this too causes a
reflection, only this time the wave is reflected back without a phase
reversal. The amplitude of the reflected wave in both these cases
equals the amplitude of the incident wave.

Now imagine that some friction between the sliding ring and the rod can
be added in varying amounts. This friction would be proportional to the
conductance in an electrical circuit, and would be infinite at one
extreme and zero at the other. The greater the friction, the greater
the conductance (and the lower the electrical resistance). As we begin
to increase the friction (conductance) from zero, the amplitude of the
inverted, reflected wave begins to decrease. The decrease in amplitude
continues with increasing friction until the amplitude of the reflected
wave becomes zero. It could be said that this value is equal to the Z0
of the transmission line.

As the amount of friction is increased still further, a small reflection
once again begins to appear. Only now the phase is opposite from what
it was before. Further increases in friction produce further increases
in reflection amplitude until the amplitude of the reflected wave once
again equals the amplitude of the incident wave.

What we noticed in the exercise is that there is some value of friction
(conductance or resistance) for which no reflection occurs. The exact
value depends on the medium through which the wave is propagating. All
other values produced a reflection.

There is no perfect explanation, and this certainly isn't a perfect
analogy but I hope that it will at least help give you a little more of
a feel for the idea.

73, Jim AC6XG