On Dec 28, 2:44*pm, Cecil Moore wrote:
Keith Dysart wrote:
I suppose this non-sequitor means that you agree that
an ideal section of transmission line, just like an
ideal inductor and capacitor, will store energy forever
if provided with the appropriate initial conditions,
but do not wish to admit it.

I freely admit that it can happen in your mind (like
leaping tall buildings at a single bound).

Thought experiments do usually occur within the mind.
This one is no different.

I do not
believe it can happen in a real-world situation.

That is good, for it is unlikely, though with superconductors
one might come close.

But
if you can demonstrate lossless transmission lines
and lossless inductors on the bench, be my guest and
probably win a Nobel Prize in the process.

More intrigue. This path has been trod before. Begin
with an experiment using ideal elements. Get
uncomfortably close to some truth. Declare the
experiment invalid because it could not happen
in the "real world".

It would be more valuable were you to confront
the demons rather than take the "real world"
escape.

An intriguing thought experiment is to take several
of these sections with stored energy (with the proper
phase relationship) and connect them together. Do
the reflections present at the ends of the short
sections suddenly disappear when the sections
are connected to form a longer line? Are the
reflections now only occurring at the ends of
the longer section?

Reflections are impossible except at physical impedance
discontinuities. There are zero reflections at a point
in a smooth fixed Z0 section of transmission line. Cut
the line and you get 100% reflection.

That is why it is so intriguing. The voltage and current
conditions have not changed, and yet, befo reflections,
after: none.

That's why your
assertions of "no change" don't make sense.

Are you claiming that the voltages or currents
have changed? Identify a measurable value that has
changed and the proof will be yours.

You would
have us believe that short circuit to open circuit is
"no change"???

If it does not change the circuit conditions, i.e.
voltages or currents.

If that is true, there's "no change"
between a shorted 1/4WL stub and an open 1/4WL stub.

Invalid generalization. We were discussing a specific
circuit, not any old 1/4WL stub.

...Keith

Keith Dysart wrote:
On Dec 28, 2:44 pm, Cecil Moore wrote:
Keith Dysart wrote:
I suppose this non-sequitor means that you agree that
an ideal section of transmission line, just like an
ideal inductor and capacitor, will store energy forever
if provided with the appropriate initial conditions,
but do not wish to admit it.
I freely admit that it can happen in your mind (like
leaping tall buildings at a single bound).

Thought experiments do usually occur within the mind.
This one is no different.

I do not
believe it can happen in a real-world situation.

That is good, for it is unlikely, though with superconductors
one might come close.

But
if you can demonstrate lossless transmission lines
and lossless inductors on the bench, be my guest and
probably win a Nobel Prize in the process.

More intrigue. This path has been trod before. Begin
with an experiment using ideal elements. Get
uncomfortably close to some truth. Declare the
experiment invalid because it could not happen
in the "real world".
. . .

Oh, boy, the thought of Cecil doing his "proofs" without using lossless
lines, pure resistances, inductances, or capacitances, lossless antenna
conductors, or any other non-real-world components is enough to tempt me
to de-plonk him just to watch the show. But I'm afraid it'll just add
more DOO (Degrees Of Obfuscation) to his already formidable toolbox of
obscuring and misdirecting techniques. Oh well.

Roy Lewallen, W7EL

Roy Lewallen wrote:
Oh, boy, the thought of Cecil doing his "proofs" without using lossless
lines, pure resistances, inductances, or capacitances, lossless antenna
conductors, or any other non-real-world components is enough to tempt me
to de-plonk him just to watch the show. But I'm afraid it'll just add
more DOO (Degrees Of Obfuscation) to his already formidable toolbox of
obscuring and misdirecting techniques. Oh well.

Roy, why must you resort to ad hominem attacks?
Does it mean that you are incapable of winning the
argument on technical merit?

You have even proved yourself and W8JI wrong about
using standing-wave current to "measure" the delay
through a 75m loading coil and don't even seem to
realize it. Here's the equation you posted:

v(t, x) = 2 * cos(x) * sin(wt)

The equation for I(t, x) would be similar with a
90 degree offset. Please come down from your ivory
tower and explain how that current can be used to
measure delay through a coil.

The point I was making is when imagination is allowed
to run wild in religion or in technical arguments,
anything is possible in the human mind. There simply
has to be a limit oriented to reality.

When a cable is cut at a point where it is known to
be transferring energy in both directions, it is no
longer transferring energy in both directions. That
is reality. No flights of fantasy will change that
technical fact.
--
73, Cecil http://www.w5dxp.com

Keith Dysart wrote:
More intrigue. This path has been trod before. Begin
with an experiment using ideal elements. Get
uncomfortably close to some truth. Declare the
experiment invalid because it could not happen
in the "real world".

When a thought experiment deviates far enough from
reality to become impossible, it is necessary to
recognize that one has crossed the line between
reality and mental masturbation. Would you like to
debate how many angels can dance on the head of
a pin?

It would be more valuable were you to confront
the demons rather than take the "real world"
escape.

I have confronted the supernatural and don't believe
in it. Your mileage may vary.

That is why it is so intriguing. The voltage and current
conditions have not changed, and yet, befo reflections,
after: none.

So changes have indeed occurred. A video signal is
a very good one to use to actually see the changes.
If you want to sweep the technical facts under the
rug, now is the time to remind me that a video signal
is not steady state.

Are you claiming that the voltages or currents
have changed?

Of course not. I am claiming that reflections have
*changed* and you seem to agree.

If ignorance is really your goal, why not drop the
experiment in the deepest part of the Pacific Ocean
where nobody can know anything about it?
--
73, Cecil http://www.w5dxp.com

On Dec 28, 7:48*pm, Cecil Moore wrote:
Keith Dysart wrote:
More intrigue. This path has been trod before. Begin
with an experiment using ideal elements. Get
uncomfortably close to some truth. Declare the
experiment invalid because it could not happen
in the "real world".

When a thought experiment deviates far enough from
reality to become impossible, it is necessary to
recognize that one has crossed the line between
reality and mental masturbation. Would you like to
debate how many angels can dance on the head of
a pin?

Still sidetracking away from your demons rather
than confronting them?!

It would be more valuable were you to confront
the demons rather than take the "real world"
escape.

I have confronted the supernatural and don't believe
in it. Your mileage may vary.

That is why it is so intriguing. The voltage and current
conditions have not changed, and yet, befo reflections,
after: none.

So changes have indeed occurred. A video signal is
a very good one to use to actually see the changes.
If you want to sweep the technical facts under the
rug, now is the time to remind me that a video signal
is not steady state.

You've got that right. And nor is it the experiment
under discussion.

Are you claiming that the voltages or currents
have changed?

Of course not.

So whether the line is cut or not, the same voltage,
current and power distribution exist.

But when the line is cut, it is clear that no
energy is moving between the separate sections.

When the lines are joined, the voltage, current and
power distributions on the line remain the same.
Therefore, no energy is being transferred between
the now joined sections.
QED

With or without reflections, no energy crosses
the points on the line with zero current.

...Keith

Keith Dysart wrote:
Still sidetracking away from your demons rather
than confronting them?!

No, you are the one who believes in the supernatural,
not I. I have confronted those supernatural demons
and decided they don't even exist in reality.

But when the line is cut, it is clear that no
energy is moving between the separate sections.

Just as it is clear that before the cut, energy
was moving between the separate sections. It
requires belief in a supernatural to assert that
is not a change.

When the lines are joined, the voltage, current and
power distributions on the line remain the same.
Therefore, no energy is being transferred between
the now joined sections.
QED

Change the QED to BS and you will have it right.
When the lines are joined, there is no longer a
physical impedance discontinuity so reflections
are impossible and energy starts flowing again
in both directions.

Believing that reflections can occur where there
exists no physical impedance discontinuity is a
religion, not a science. At that point, I draw
the line - but you are free to have the religion
of your choice. Just please don't try to force
your religion on this technical newsgroup.

With or without reflections, no energy crosses
the points on the line with zero current.

Make that no *NET* energy and you will be so
technically correct that I will agree with you.
--
73, Cecil http://www.w5dxp.com

On Dec 29, 9:59*am, Cecil Moore wrote:
Keith Dysart wrote:
Still sidetracking away from your demons rather
than confronting them?!

No, you are the one who believes in the supernatural,
not I. I have confronted those supernatural demons
and decided they don't even exist in reality.

Well something causes you to latch up and bail with
"its not real world", though there was no protest
when the initial experiment is specified using
ideal elements.

But when the line is cut, it is clear that no
energy is moving between the separate sections.

Just as it is clear that before the cut, energy
was moving between the separate sections. It
requires belief in a supernatural to assert that
is not a change.

But you previously agreed that P(t) = 0 for all t,
and therefore no energy was moving between the sections.
Recall that P(t) = V(t) * I(t) and that at the
point on the line in question, I(t) is zero for all
t, therefore P(t) is zero for all t. So no energy
flow between the sections.

When the lines are joined, the voltage, current and
power distributions on the line remain the same.
Therefore, no energy is being transferred between
the now joined sections.
QED

Change the QED to BS and you will have it right.

This is the kind of comment that suggests stress,
rather than rational examination.

When the lines are joined, there is no longer a
physical impedance discontinuity so reflections
are impossible and energy starts flowing again
in both directions.

But as previously discussed, no energy flows. The
the voltage, current and power distributions are
the same, whether the line is cut or joined.

Believing that reflections can occur where there
exists no physical impedance discontinuity is a
religion, not a science.

Red herring. Straw man. I do not recall anyone
making the claim that reflections exist with no
physical impedance discontinuity. (Although you
did raise the possibility in another post).

At that point, I draw
the line - but you are free to have the religion
of your choice. Just please don't try to force
your religion on this technical newsgroup.

With or without reflections, no energy crosses
the points on the line with zero current.

Make that no *NET* energy and you will be so
technically correct that I will agree with you.

Sometimes when writers write NET, they mean time
averaged, but that is not your intent here, is it?

You do mean that P(t) is zero for all t at the
points on the open circuited line where the voltage
or current is always zero. Right?

...Keith

Keith Dysart wrote:
Well something causes you to latch up and bail with
"its not real world", ...

Don't feel unique - I do the same thing when someone
says God created the heavens and earth in 6 days.

You are either confused about what I said (or deliberately
bearing false witness). Please correct your confusion
(or lack of ethics) or I will stop responding.

Bottom line: At points '+' in the example before any
cutting, either reflections exist or they don't.

If reflections exist, there has to exist an impedance
discontinuity to cause the reflections. There is no
impedance discontinuity.

If reflections don't exist, there is nothing to change
the direction of the flowing energy. Therefore, energy
is flowing both ways through the '+' points. The *NET*
energy flow is zero. But it is easily proven that
energy is flowing from one SGCL to the other.
--
73, Cecil http://www.w5dxp.com

On Dec 30, 9:42*am, Cecil Moore wrote:
Bottom line: At points '+' in the example before any
cutting, either reflections exist or they don't.

If reflections exist, there has to exist an impedance
discontinuity to cause the reflections. There is no
impedance discontinuity.

If reflections don't exist, there is nothing to change
the direction of the flowing energy. Therefore, energy
is flowing both ways through the '+' points.

Now there's a bit of a pickle. You previously agreed
that
P(x,t) = V(x,t) * I(x,t)
but now you claim that there is energy flowing.

If you do not accept that P = V * I, please clearly
state so. The discussion could then continue with
the more basic issue.

The *NET* energy flow is zero.

NET energy flow is not defined in your favourite
reference: the IEEE dictionary.

How does it differ from "instantaneous power" for
which the IEEE does have a definition (P=V*I, if
you are interested)?

But it is easily proven that energy is flowing
from one SGCL to the other.

It would be wonderful if you could provide this
easy PROOF since such a proof would settle the
question.

...Keith