On 17 jun, 21:30, Cecil Moore wrote:
On Jun 17, 7:00*pm, Keith Dysart wrote:

An ideal conductor has
zero resistance, so current can flow without voltage in an ideal
conductor.

Quoting "Fields and Waves ...", by Ramo and Whinnery: "A perfect
conductor is usually understood to be a material in which there is no
electric field at any frequency. Maxwell's equations ensure that there
is then also no time-varying magnetic field in the perfect conductor."
How does one go from zero current to a non-zero current if the
magnetic field is prohibited from varying (changing) with time?
--
73, Cecil, w5dxp.com

An ideal conductor has
zero resistance, so current can flow without voltage in an ideal
conductor.

Inertia first Newton law applied to the free electron lttle balls
perhaps?
Now, if at first of experiment little balls was at rest, how do they
set in movement without a force? Tell us.
......
Keith, OM, if you do not make the rope experiment, make this another
simple one = get from Radio Shack a long, long lossles TL, (with
vf=1, why not?), 6*10^8 meters long it is good, open or short ended
(it does not matter). Connect it to your 100 W rig, key for a one
second the TX full CW power, inmediately disconnect the TL and touch
the connector with your fingers. Just count: tree, two, one, ¡zero!.
If after "zero" you still with the connector in your fingers without
blink, then reflected waves really have not too much reality... have
some ointment for burns, may be the boys are right.) (sorry, do not
be angry with me I am practicing translate some creole humor to
english :D )

73 Miguel LU6ETJ

On Jun 17, 10:57*pm, lu6etj wrote:
On 17 jun, 21:30, Cecil Moore wrote:





On Jun 17, 7:00*pm, Keith Dysart wrote:

An ideal conductor has
zero resistance, so current can flow without voltage in an ideal
conductor.

Quoting "Fields and Waves ...", by Ramo and Whinnery: "A perfect
conductor is usually understood to be a material in which there is no
electric field at any frequency. Maxwell's equations ensure that there
is then also no time-varying magnetic field in the perfect conductor."
How does one go from zero current to a non-zero current if the
magnetic field is prohibited from varying (changing) with time?
--
73, Cecil, w5dxp.com
An ideal conductor has
zero resistance, so current can flow without voltage in an ideal
conductor.

Inertia first Newton law applied to the free electron lttle balls
perhaps?
Now, if at first of experiment little balls was at rest, how do they
set in movement without a force? Tell us.
.....
Keith, OM, *if you do not make the rope experiment, *make this another
simple one = *get from Radio Shack a long, long lossles TL, (with
vf=1, why not?), 6*10^8 meters long it is good, open or short ended
(it does not matter). Connect it to your 100 W rig, key for a one
second the TX full CW power, inmediately disconnect the TL and touch
the connector with your fingers. Just count: tree, two, one, ¡zero!.
If after "zero" you still with the connector in your fingers without
blink, then reflected waves really have not too much reality... have
some ointment for burns, may be the boys are right.) (sorry, do not
be angry with me I am practicing translate some creole humor to
english :D *)

73 Miguel LU6ETJ- Hide quoted text -

- Show quoted text -

Good day Miguel,

In the example you provide, there would be real energy flowing and
it would be clearly shown by
P(t)=V(t)*I(t)
P(t) will be negative because the energy is flowing in the reverse
direction.

Computing Pf and Pr would reveal
Pf(t)=0
Pr(t)=-P(t)

So Pf(t)-Pr(t) = P(t) as it must.

I see no conflict with anything that I have written previously.

There are many examples where one can observe energy flow in a
reflected wave.

It just takes one counter-example to demonstrate that this is not
always
the case and that one should not assign *too* much reality to such
waves.

What this neans is that when someone asks "what happesn to reflected
energy?", the first question you have to answer is "Is this a
situation
where the computed reflected power represents something real?"
because
if it does not, the original question is moot.

....Keith

On Jun 18, 6:00*am, Keith Dysart wrote:
"Is this a situation
where the computed reflected power represents something real?"
because if it does not, the original question is moot.

It certainly depends upon your definition of "power" and that
definition is different between pure physics and RF engineering. One
of the accepted definitions of "power" in "The IEEE Dictionary"
contradicts the definition of "power" given in my college physics
book. "The IEEE Dictionary" says that flowing energy passing a fixed
measurement point is power, by definition.

If there is anything at all that can be measured, it must necessarily
contain energy. If the EM energy is moving, it is power, by IEEE
definition. If you disagree, take it up with The IEEE.

So the actual question that needs to be answered is: Does the
electromagnetic reflected wave contain energy traveling at the speed
of light in the medium? The answer is yes, being photonic in nature,
an EM wave must necessarily contain an ExH power density and,
consisting of photons, must necessarily be traveling at the speed of
light in the medium. The EM wave will continue to travel in the
direction of energy flow at the speed of light in the medium until it
encounters an impedance discontinuity which causes a reflection and/or
interference.

There is really no difference in a forward wave and a reflected wave
except for the direction of travel. They both contain an associated
ExH power density. One can set up identical signal generators at each
end of a transmission line to emulate forward and reflected waves.
Which generator yields forward waves and which generator yields
reflected waves? It doesn't really matter because direction is only a
convention.
--
73, Cecil, w5dxp.com

On 18 jun, 12:26, Cecil Moore wrote:
On Jun 18, 6:00*am, Keith Dysart wrote:

"Is this a situation
where the computed reflected power represents something real?"
because if it does not, the original question is moot.

It certainly depends upon your definition of "power" and that
definition is different between pure physics and RF engineering. One
of the accepted definitions of "power" in "The IEEE Dictionary"
contradicts the definition of "power" given in my college physics
book. "The IEEE Dictionary" says that flowing energy passing a fixed
measurement point is power, by definition.

If there is anything at all that can be measured, it must necessarily
contain energy. If the EM energy is moving, it is power, by IEEE
definition. If you disagree, take it up with The IEEE.

So the actual question that needs to be answered is: Does the
electromagnetic reflected wave contain energy traveling at the speed
of light in the medium? The answer is yes, being photonic in nature,
an EM wave must necessarily contain an ExH power density and,
consisting of photons, must necessarily be traveling at the speed of
light in the medium. The EM wave will continue to travel in the
direction of energy flow at the speed of light in the medium until it
encounters an impedance discontinuity which causes a reflection and/or
interference.

There is really no difference in a forward wave and a reflected wave
except for the direction of travel. They both contain an associated
ExH power density. One can set up identical signal generators at each
end of a transmission line to emulate forward and reflected waves.
Which generator yields forward waves and which generator yields
reflected waves? It doesn't really matter because direction is only a
convention.
--
73, Cecil, w5dxp.com

Hello friends. good day for you.

I am glad that I have not bothered with my joke, Keith! :) I was to
do some comments to your and Roy posts, but I prefer to ask questions
rather than giving personal opinions :)
.....
Please Cecil, friend, do not mention photons and optics (do not bother
me, don't worry), I believe you better play your game without such
things. I know is like fighting with one arm tied, but I think you
can, make an effort :)

Please Owen explain to me what is "negative power".

In the other thread you said = "The notion that reflected power is
simply and always absorbed in the real source resistance is quite
wrong. Sure you can build special cases where that might happen, but
there is more to it. Thinking of the reflected wave as 'reflected
power' leads to some of the misconception.
Then I asked; "remember me what reflected power definition are you
using here and expand the sentence idea".
I did not ask for the quoting, I ask (again) for your concept of
Reflected Power. I do not sure if you accept (or not) the very notion
of reflected power as legitimate. The sentence it is not clear enough
to me.

Please, tell us if you accept the idea of two very directive
electromagnetic waves from different sources flowing in opposite
directions as carring independent energy (with different frequencies
at first) and information, and the posibbility that energy be
dissipated and/or transmitted by de opposite system and the
information being recovered in both ends.
If your answer is yes, then tell us if you conceive such similar
system using a same wave guide to simultaneously vinculate both
system.

73 - Miguel - LU6ETJ

PS: Roy, friend, take it ease (is OK, or polite say "take it easy?),
references to the article were only to complement (bring close?) some
useful notions related, mentioning a possible common reference (my
english books are few, old and possibly useless as reference
nowadays)

On Jun 18, 1:01*pm, lu6etj wrote:
Please Cecil, friend, do not mention photons and optics (do not bother
me, don't worry), ...

What do I do about people who assert that RF waves possess the ability
to violate the known laws of EM wave physics? It doesn't matter what
the frequency of an EM wave is, it must obey the laws of physics, two
of which a

1. It cannot exist without a Poynting vector ExH power density.

2. It must necessarily move at the speed of light in the medium.
--
73, Cecil, w5dxp.com