Jim Kelley wrote:

Cecil Moore wrote:
Where did I go wrong in the following logic? You have said there is
no energy in those reverse-traveling waves. Waves cannot exist without
energy. Therefore, reflected waves don't exist. Since they don't exist,
they cannot cause standing waves.

You went wrong in the first sentence. That statement is false.

So you are saying that there is energy in those reverse-traveling waves?
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:

Jim Kelley wrote:

Cecil Moore wrote:
Where did I go wrong in the following logic? You have said there is
no energy in those reverse-traveling waves. Waves cannot exist without
energy. Therefore, reflected waves don't exist. Since they don't exist,
they cannot cause standing waves.

You went wrong in the first sentence. That statement is false.

So you are saying that there is energy in those reverse-traveling waves?

What does "energy in" waves mean? Energy is required in order to
generate EM waves. Energy can be transferred from one place to another
by EM waves (if a conversion in form takes place at both places, or
there is otherwise a change in the total energy at both places). And
standing EM waves can store energy. But to infer that energy is being
transferred from one place to another from the mere presence of waves
could lead one to some wrong conclusions.

73, Jim AC6XG

Jim Kelley wrote:

Cecil Moore wrote:
Since waves cannot
exist without energy moving past a point, we can deduce that the
person has strongly implied that reflected waves don't exist.

100 watt rf generator driving an open, lossless transmission line. How
much energy do you think moves past a given point along the line every
second? 100 Joules, 200 Joules, or zero Joules?

Equip the RF generator with a perfect circulator plus load and it is
easy to measure 100 watts out of the generator and 100 watts dissipated
by the circulator load. The 100 watts dissipated by the circulator load
makes a round trip to the open end of the transmission line and back
as can be proven using TV ghosting or a TDR. A Bird directional wattmeter
will read 100 watts in either direction.

So, to answer your question: There is 100 watts forward power and 100
watts of reflected power anywhere along that line. The *NET* power
flow is, of course, zero. I believe this is all explained in Johnson's
textbook under "forward power flow vector" and "reverse power flow
vector". I'm at work and don't have my references handy.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:

Jim Kelley wrote:

Cecil Moore wrote:
Since waves cannot
exist without energy moving past a point, we can deduce that the
person has strongly implied that reflected waves don't exist.

100 watt rf generator driving an open, lossless transmission line. How
much energy do you think moves past a given point along the line every
second? 100 Joules, 200 Joules, or zero Joules?

Equip the RF generator with a perfect circulator plus load and it is
easy to measure 100 watts out of the generator and 100 watts dissipated
by the circulator load. The 100 watts dissipated by the circulator load
makes a round trip to the open end of the transmission line and back
as can be proven using TV ghosting or a TDR. A Bird directional wattmeter
will read 100 watts in either direction.

What do you think the Bird actually measuring?

Instead of posing and then solving a different problem, why not just
answer the question I asked?

73, Jim AC6XG

Jim Kelley wrote:
But to infer that energy is being
transferred from one place to another from the mere presence of waves
could lead one to some wrong conclusions.

All EM waves contain moving energy and cannot stand
still. To argue otherwise is just denying reality.
--
73, Cecil http://www.qsl.net/w5dxp

"Jim Kelley" wrote in message
...


Cecil Moore wrote:

Jim Kelley wrote:

Cecil Moore wrote:
Since waves cannot
exist without energy moving past a point, we can deduce that the
person has strongly implied that reflected waves don't exist.

100 watt rf generator driving an open, lossless transmission line.
How
much energy do you think moves past a given point along the line every
second? 100 Joules, 200 Joules, or zero Joules?

Equip the RF generator with a perfect circulator plus load and it is
easy to measure 100 watts out of the generator and 100 watts dissipated
by the circulator load. The 100 watts dissipated by the circulator load
makes a round trip to the open end of the transmission line and back
as can be proven using TV ghosting or a TDR. A Bird directional
wattmeter
will read 100 watts in either direction.

What do you think the Bird actually measuring?

Instead of posing and then solving a different problem, why not just
answer the question I asked?

73, Jim AC6XG

because that is not cecil's way, he will restate whatever is posed so that
he can answer it with his favorite discussion topics. any discussion like
this on here ends the same way with the same 3 or 4 combatants each stating
their viewpoint, all of which kind of say the same thing in different terms,
and none of them able to acknowledge that the other ones may be right...
either that or one of them who is outright wrong will persist and keep
redirecting the thread until he wins by default. its nothing but a big game
that confuses everyone until they catch on. on a cold winter day it can be
fun, take one of the examples and solve it a different way (i prefer
sinusoidal steady state) and watch them all pull apart the obvious correct
answer with their own methods... it can keep you laughing for weeks!

Cecil Moore wrote:
All EM waves contain moving energy and cannot stand
still. To argue otherwise is just denying reality.

I understand your point. But arguing that energy changes direction
without reflection, dispersion, or diffraction is an attempt at
inventing reality.

73, Jim AC6XG

Jim Kelley wrote:
What do you think the Bird actually measuring?

It is phasor-adding/subtracting a voltage proportional to the
RF voltage to/from a voltage proportional to the RF current.

Instead of posing and then solving a different problem, why not just
answer the question I asked?

I did. I'm sorry you didn't like it. I'm not going to get involved in
a pi$$ing contest over the impedance of a transmitter and what happens
to reflected waves incident upon it.
--
73, Cecil http://www.qsl.net/w5dxp

Jim Kelley wrote:

Cecil Moore wrote:
All EM waves contain moving energy and cannot stand
still. To argue otherwise is just denying reality.

I understand your point. But arguing that energy changes direction
without reflection, dispersion, or diffraction is an attempt at
inventing reality.

I'm not arguing that at all. In a transmission line, destructive
interference causes an energy reflection in which the ratio of
the E-field to H-field is transformed from one characteristic
impedance to another. It's all described on the Melles-Groit
web page. They don't call it an energy reflection but that's
what it is.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:

Jim Kelley wrote:

Cecil Moore wrote:
All EM waves contain moving energy and cannot stand
still. To argue otherwise is just denying reality.

I understand your point. But arguing that energy changes direction
without reflection, dispersion, or diffraction is an attempt at
inventing reality.

I'm not arguing that at all. In a transmission line, destructive
interference causes an energy reflection in which the ratio of
the E-field to H-field is transformed from one characteristic
impedance to another. It's all described on the Melles-Groit
web page. They don't call it an energy reflection but that's
what it is.

Really? It doesn't act like a reflection. There isn't a reflective
surface. The amplitude of the "reflection" seems unrelated to any
"reflection" coefficient. If it were a reflection, I think it would be
much easier to understand - much less controversial. Don't you agree?

73, Jim AC6XG