Cecil Moore wrote:

Jim Kelley wrote:

Cecil Moore wrote:

You are technically correct but it doesn't matter.


You just spent 4 years vehemently arguing the exact opposite point of
view.


BS!

Now you're vehemently arguing about whether you argued or not.

What I have said lately is that any number of knowledgeable
engineers and authors have an expanded definition of power.

That was never in dispute. You argued that power propagates and
reflects, and I explained that it doesn't. Now you're behaving like a
child.

ac6xg

Jim Kelley wrote:
You argued that power propagates and
reflects, and I explained that it doesn't.

Jim, you know that isn't true. After you reviewed my article,
I changed every occurence of "reflected power" to "reflected
energy" just to satisfy you. You have never been able to
back up your assertions about what I have said with any
quotes of mine. Wonder why?

So once again, I challenge you to produce a quote where I
said power propagates and reflects. I have always said that
energy propagates and reflects and power is the measurement
of that energy flowing past a point.
--
73, Cecil http://www.qsl.net/w5dxp

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Jim Kelley wrote:
You argued that power propagates and
reflects, and I explained that it doesn't.

Jim, here's a posting from last year that proves your assertion
to be false. I agreed with you last year that power doesn't
flow and isn't reflected. I agreed with you that it is energy
that flows and is reflected. I agreed with you that power is
measured at a point. Seems an apology is in order.

Newsgroups: rec.radio.amateur.antenna
From: Cecil Moore
Date: Thu, 02 Dec 2004 14:28:20 -0600
Subject: Additional Line Losses Due to SWR

Jim Kelley wrote:
The crux of
the phenomenological problem is that power does not flow or move, nor is
it something that is reflected.

But energy does flow and move and is something that can be reflected.
You can easily see the energy packets using a TDR. Without energy,
those pulses wouldn't exist. The energy is obviously in the pulse,
where the voltage and current are.

And joules of energy flowing past a point is joules/sec, i.e. power,
by IEEE definition.
--
73, Cecil http://www.qsl.net/w5dxp

--
73, Cecil http://www.qsl.net/w5dxp


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On Tue, 02 Aug 2005 16:04:29 -0500, Cecil Moore
wrote:

Jim Kelley wrote:

Cecil Moore wrote:
You can add Walter Johnson, Simon Ramo, and John Whinnery to
that list. "Power in the reflected wave" is commonly mentioned.

Proving what, exactly? That power is "in" a reflected wave?

Proving that "Power in the reflected wave" is common
usage in RF engineering. You are not going to get the
human race to stop using the word, "sunrise", no
matter what you say or do.

Jim, I'm sure you'll agree that voltage is reflected, and that current
is also reflected. Then isn't the product of voltage and current
power?

Walt, W2DU

Walter Maxwell wrote:

Cecil Moore wrote:
Proving that "Power in the reflected wave" is common
usage in RF engineering.

Jim, I'm sure you'll agree that voltage is reflected, and that current
is also reflected. Then isn't the product of voltage and current
power?

I think I understand Jim's point that power is measured
relative to a stationary point or plane. The Bird wattmeter
is stationary in the transmission line and measures the
average energy/time flowing through it. Average power is
averaged over at least one complete cycle. It is hard to
visualize an average power meter measurement while the meter
is moving with the wave - admittedly an esoteric point and
not likely to have any effect on common usage.

Consider that it is the instantaneous value of voltage and
current that is reflected (actually the instantaneous E-field
and H-field). The RMS value of voltage and current is not
what is actually reflected in reality. But again, shortcuts
and common usage rule the day.
--
73, Cecil http://www.qsl.net/w5dxp

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Jim Kelley wrote:
"---power does not flow or move, nor is it something that can be
reflected."

From the Random House American College Dictionary:
Power is the ability to do or act. It is the time rate of transferring
or transforming energy. It is work done or energy transferred per unit
of time.

The power to do or act can be moved from one location to another. A
power house is an electrical generating station where some other form of
energy is converted to electricity which is very flexible in
application.

From the power house, the power (ability to do or act) is transported by
power transmission lines to the places it is used.

Since the wavelength at 60 Hz is 5 million meters, (5000 km), power
transmission lines aren`t long enough to produce standing waves which
are caused by reflections.

Radio-frequency transmission lines are often long enough to show the
effects of reflections and the standing waves produced by those
reflections.

Power flows in r-f lines and it is reflected at impedance
discontinuities accordimg to the most knowledgeable experts. F.E. Terman
is my favorite.

Best regards, Richard Harrison, KB5WZI

Walter Maxwell wrote:
On Tue, 02 Aug 2005 16:04:29 -0500, Cecil Moore
wrote:


Jim Kelley wrote:


Cecil Moore wrote:

You can add Walter Johnson, Simon Ramo, and John Whinnery to
that list. "Power in the reflected wave" is commonly mentioned.

Proving what, exactly? That power is "in" a reflected wave?

Proving that "Power in the reflected wave" is common
usage in RF engineering. You are not going to get the
human race to stop using the word, "sunrise", no
matter what you say or do.


Jim, I'm sure you'll agree that voltage is reflected, and that current
is also reflected. Then isn't the product of voltage and current
power?

Walt, W2DU

I hope I haven't given the impression that I would be unfamiliar with
that relationship. I used it in my work practically every day of my
life for many years.

Here's my best answer to such a question. According to the physics that
I've studied, physicists seem to be laboring under the impression that
it is the electric and magnetic fields which actually propagate and
interact with matter. That interaction can result in, among other
things, reflection. The E&H fields manifest themselves within matter as
voltages and currents, respectively. Although it is the fields which
reflect, it is the resulting voltages and currents that we can most
readily measure. From a practical everyday standpoint this distinction
makes little or no difference. It is only when we start to describe
physical processes such as energy flow that it may become necessary to
consider the distinction.

And yes, if you take a calculator or slide rule and multiply voltage and
current, and make certain assumptions, you can find the rate at which
energy is probably being transferred from one place to some other place.
But some folks have argued descriptions of physical phenomena derived
from an assumption that the number displayed on the calculator
physically propagates through a transmission line, physically reflects
off the ends of the transmission line or other discontinuities, and
physically interferes with itself or other numbers like it. So that
there is no further mistaking my position, I dispute the validity of
these descriptions of the behavior of physical phenomena, and some of
the predictions based upon them. I do not dispute P=V*I, but thanks for
asking.

The wave which propagates along a transmission line can produce energy
at a rate proportional to E x H, but it is not E x H which propagates
along the transmission line. E propagates in one plane, and H
propagates in a plane a right angles to E. When we know the
characteristics of E and H (or V and I) individually, we can predict
what will occur when either encounters a discontinuity. But when we
multiply to two together, the resulting magnitude no longer possesses
the properties of either of the multiplicands, and so no accurate
predictions about interactions with discontinuities can truly be derived
without making assumptions. And as we've seen, given a nebulous laundry
list of assumptions, some inaccurate predictions can be derived.

Your 'Transformer' diagrams come as close as any I've seen to describing
how things behave in an coaxial impedance matching arrangement. I hope
you include them in your 3rd Edition. I have, by the way, found similar
but less detailed drawings of thin film interfaces in two different
physics textbooks. I think the key to understanding them is the
superposition of multiple reflections.

73, Jim AC6XG

Whatever floats your boat, Richard. If you need to think of power as an
'ability' that flows through an electrical pipe, then I think you should
think of it that way.

73, Jim

Richard Harrison wrote:

Jim Kelley wrote:
"---power does not flow or move, nor is it something that can be
reflected."

From the Random House American College Dictionary:
Power is the ability to do or act. It is the time rate of transferring
or transforming energy. It is work done or energy transferred per unit
of time.

The power to do or act can be moved from one location to another. A
power house is an electrical generating station where some other form of
energy is converted to electricity which is very flexible in
application.

From the power house, the power (ability to do or act) is transported by
power transmission lines to the places it is used.

Since the wavelength at 60 Hz is 5 million meters, (5000 km), power
transmission lines aren`t long enough to produce standing waves which
are caused by reflections.

Radio-frequency transmission lines are often long enough to show the
effects of reflections and the standing waves produced by those
reflections.

Power flows in r-f lines and it is reflected at impedance
discontinuities accordimg to the most knowledgeable experts. F.E. Terman
is my favorite.

Best regards, Richard Harrison, KB5WZI

On Wed, 03 Aug 2005 11:54:08 -0700, Jim Kelley
wrote:

I have, by the way, found similar
but less detailed drawings of thin film interfaces in two different
physics textbooks. I think the key to understanding them is the
superposition of multiple reflections.

Hi Jim,

Such coverage as you describe, in physics textbooks, are rudimentary
discussions suitable for introductory purposes. They are not the
end-all be-all nor final word on the matter. This is born out by
exhausting work being pursued by many in academia and the industry to
"completely cancel" reflections. They would not be so engaged in this
work if a simple, quarterwave, thin layer optic performed this
complete cancellation already. The fact of the matter is that by the
mechanics so described in the text books, they guarantee no totality
of cancellation. True, they offer a close hit, but this is not proof
of totality. Close is good enough for nuclear hand grenades too.

When the energy available in the first medium, at the second
interface, cannot possibly reflect enough of it to the first
interface; then no amount of superposition of ALL reflections (and
this presumes that the second interface is fully reflecting for these
succeeding multiples, an absurd notion in its own right) can exceed
that available energy.

Yes, this has all been said before, you've found it interesting but
not compelling; and yet no one here has offered any way to boost the
energy to completely cancel the reflection from the first interface.

Under the circumstances already described, those reflection products
(after assuming ALL the multiple reflections have been ushered out
from behind the first interface to destructively interfere) contain:
1800 TIMES MORE POWER THAN THE SUN!
which has been humorously relegated to zero. :-)

Flowing, dribbling, puddling, or simply expressed in terms of candelas
per square foot per fortnight, it all leads to the same conclusion:
the cancellation is not total. Hence the subject line of
The Extreme Failure of Poor Concepts
in Discussing Thin Layer Reflections

********* for those who cannot cope with the topic *************

I have a D Cell battery whose capacity is 3 W-HR, and I roll it along
the floor.

Has power flowed?

How much? (sorry if I offended anyone by asking for a quantitative
answer)

73's
Richard Clark, KB7QHC

Richard Clark wrote:

On Wed, 03 Aug 2005 11:54:08 -0700, Jim Kelley
wrote:


I have, by the way, found similar
but less detailed drawings of thin film interfaces in two different
physics textbooks. I think the key to understanding them is the
superposition of multiple reflections.


Hi Jim,

Such coverage as you describe, in physics textbooks, are rudimentary
discussions suitable for introductory purposes. They are not the
end-all be-all nor final word on the matter. This is born out by
exhausting work being pursued by many in academia and the industry to
"completely cancel" reflections. They would not be so engaged in this
work if a simple, quarterwave, thin layer optic performed this
complete cancellation already. The fact of the matter is that by the
mechanics so described in the text books, they guarantee no totality
of cancellation. True, they offer a close hit, but this is not proof
of totality. Close is good enough for nuclear hand grenades too.

When the energy available in the first medium, at the second
interface, cannot possibly reflect enough of it to the first
interface; then no amount of superposition of ALL reflections (and
this presumes that the second interface is fully reflecting for these
succeeding multiples, an absurd notion in its own right) can exceed
that available energy.

Yes, this has all been said before, you've found it interesting but
not compelling; and yet no one here has offered any way to boost the
energy to completely cancel the reflection from the first interface.

Under the circumstances already described, those reflection products
(after assuming ALL the multiple reflections have been ushered out
from behind the first interface to destructively interfere) contain:
1800 TIMES MORE POWER THAN THE SUN!
which has been humorously relegated to zero. :-)

Flowing, dribbling, puddling, or simply expressed in terms of candelas
per square foot per fortnight, it all leads to the same conclusion:
the cancellation is not total. Hence the subject line of
The Extreme Failure of Poor Concepts
in Discussing Thin Layer Reflections

********* for those who cannot cope with the topic *************

I have a D Cell battery whose capacity is 3 W-HR, and I roll it along
the floor.

Has power flowed?

How much? (sorry if I offended anyone by asking for a quantitative
answer)

73's
Richard Clark, KB7QHC

Hi Richard.

The example you provided earlier is not any result of exhaustive
research. It is not even an accurate thumbnail sketch of the phenomenon
at the level of "rudimentary physics books". So I disagree with your
assessment. (Perhaps you should consider having a look at the text
you're characterizing first before you presume to characterize it.)

But if by all that you mean to say that it's not possible to make a
perfect anything, then I think that ordinarily goes without saying. So
yes, you're right. There is no such thing as a lossless medium.
But it is a rather simple matter to get a reasonably good match using
this technique. I think you can assume that's about the degree of
accuracy we're using for most of our discussions.

73, AC6XG

PS I like your power flow analogy. :-)