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On Mar 7, 10:24*am, Cecil Moore wrote:
Dave wrote:
"Keith Dysart" wrote:
What is the mechanism that creates the effect we call interference?

superposition.

Not disagreeing - just expanding:
Superposition is certainly necessary but superposition
alone is not sufficient. Superposition can occur with
or without interference.
--
73, Cecil *http://www.w5dxp.com

So superposition is the underlying mechanism that can be used to
explain all.
Interference is a phenomon that is observed for certain particular
conditions of superposition.

Works for me.

...Keith

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Cecil Moore wrote:
Gene Fuller wrote:
You may or may not already know this, but a lot of detailed optical
analysis these days is done with full 3-D electromagnetic simulation,
starting from Maxwell equations and boundary conditions. Interference,
coherence, energy flow, and all of the other stuff you like to discuss
can be *output* from that analysis, but those items are not part of
the input. The "centuries old" optics simply does not get the job
done. The "centuries old" stuff may work in the (impossible) cases
where everything is completely lossless and ideal, but it doesn't give
the right answers in the real world.

Ideal examples are time-honored ways of discussing concepts
and getting away from the vagaries of the real world. If one
understands the ideal examples, one is in a position to then
proceed to understanding the real world. If one fails to
understand the conceptual principles underlying the ideal
examples, one cannot possibly understand the real world.

Your posting seems to reflect your usual sour grapes attitude.
I will expect you to object to every example that uses lossless
transmission lines from now on including ones by Ramo & Whinnery,
Walter Johnson, Walter Maxwell, J. C. Slater and Robert Chipman.

I don't know why you would choose to accuse me of "sour grapes". That is
a characteristic of someone who has lost an argument. 8-)

You keep referring to the optical masters of old as being a huge
resource that is largely unknown to the RF crowd. I am merely
introducing the 21st century into the discussion.

73,
Gene
W4SZ

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Cecil Moore wrote:
Gene Fuller wrote:
The definition of irradiance, according to NIST, is power per unit
area. The standard units are W/m2 or lumen/m2.

Exactly how much power can exist in a zero unit of
time?

You previously objected to things that don't match
the real world. Instantaneous irradiance would rely
on an infinitesimally small amount of time, something
that doesn't match reality very well. One would think
you would therefore object to the concept of instantaneous
irradiance since it cannot be measured in reality and
exists only in the math model in the human mind.

Still spinning the words, huh? Do you really think that "time-averaged"
and "zero" time are the only possible choices?

Do you disagree with NIST?

73,
Gene
W4SZ

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Keith Dysart wrote:
My understanding of your claim was that for the special case of
a 45 degree line supplied from a matched source, the energy
in the reflected wave is dissipated in the source resistor.

I have told you time and again that your understanding is
wrong. My claim is that for the special case of a 45 degree
phase difference between the forward wave and reflected wave,
the *average* power in the reflected wave is dissipated in the
source resistor. Irradiance is an *average* power density as
defined by Hecht, in "Optics". I have told you previously (many
times) that when I use the word "power", I am talking about
*average* power. I agree with Hecht that instantaneous power
is "of limited utility" and is therefore mostly irrelevant.

For the record - for the umteenth time: When I say "power", I
am talking about "*average* power". If I ever talk about
instantaneous power, I will say "instantaneous power". If
you still don't understand, you need professional help.

This sentence fragment from your document suggests this:
"reflected energy from the load is flowing through the source
resistor, RS, and is being dissipated there".

I left no doubt as to what I meant in my document. Here is
a quote from the second paragraph in my document:
"Please note that any power referred to in this paper
is an *average power*. Nothing is being asserted or implied about
instantaneous powers. In fact, instantaneous powers are completely
irrelevant to the following discussion."

I simply don't know how to say it any plainer than that.

I really resent your lack of ethics in this matter.
If you are forced to create a Big Lie about what I have
said in order to try to win, is it really worth it?
--
73, Cecil http://www.w5dxp.com

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Cecil Moore wrote:
K7ITM wrote:
Certainly, those who design and build FTIR spectrometers know
perfectly well that interference does not depend on a narrow-band
coherent source.

How narrow-band? How coherent? In the irradiance (power
density) equation, Ptot = P1 + P2 + 2*sqrt(P1*P2)cos(A),
if the angle 'A' is varying rapidly, what value do you
use for cos(A)?

A constant average sustained level of destructive
interference cannot be maintained between two waves
unless they are coherent. If they are not coherent
the interference will average out to zero.

Gee, I wonder if the experts may have moved beyond the elementary optics
textbook descriptions?

Are you suggesting that FTIR cannot work unless one has your nice 1-D
configurations with perfectly monochromatic waves? Does everything need
to be collinear and coherent?

73,
Gene
W4SZ

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Keith Dysart wrote:
So superposition is the underlying mechanism that can be used to
explain all.
Interference is a phenomon that is observed for certain particular
conditions of superposition.

And permanent redistribution of energy is a phenomena that is
observed for certain particular conditions of interference.

Seems like a no-brainer to me.
--
73, Cecil http://www.w5dxp.com

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Gene Fuller wrote:
Do you disagree with NIST?

Could be that NIST didn't consider the fact that someone
could stupid enough to believe in a non-zero irradiance
averaged over an instantaneous time period of zero. :-)

Official Notice: For the purposes of my postings, I am using
Hecht's definition of "irradiance", i.e. "the average energy
per unit area per unit time".
--
73, Cecil http://www.w5dxp.com

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Gene Fuller wrote:
Are you suggesting that FTIR cannot work unless one has your nice 1-D
configurations with perfectly monochromatic waves?

Have you stopped beating your wife? Please cease and
desist with your diversions in the form of innuendo.

It is not my fault that a transmission line is essentially
one-dimensional but I am willing to take technical advantage
of that fact of physics. It is not my fault that CW transmitters
emit essentially monochromatic waves but I am willing to take
technical advantage of that fact of physics.
--
73, Cecil http://www.w5dxp.com

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Gene Fuller wrote:
Cecil Moore wrote:
Gene Fuller wrote:
The definition of irradiance, according to NIST, is power per unit
area. The standard units are W/m2 or lumen/m2.

Exactly how much power can exist in a zero unit of
time?

You previously objected to things that don't match
the real world. Instantaneous irradiance would rely
on an infinitesimally small amount of time, something
that doesn't match reality very well. One would think
you would therefore object to the concept of instantaneous
irradiance since it cannot be measured in reality and
exists only in the math model in the human mind.

Still spinning the words, huh? Do you really think that "time-averaged"
and "zero" time are the only possible choices?

Do you disagree with NIST?

73,
Gene
W4SZ

Cecil must have flunked calculus. Also, differential calculus is
the life-blood of classical electromagnetic theory. The ancients used
it liberally. Cecil probably doesn't believe in speed, because speed is
also an instantaneous quantity. Maybe he can use his argument on the
next ham-fisted Texas trooper who stops him for speeding on his motorcycle.
73,
Tom Donaly, KA6RUH

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On Mar 7, 5:31*pm, Cecil Moore wrote:
Keith Dysart wrote:
My understanding of your claim was that for the special case of
a 45 degree line supplied from a matched source, the energy
in the reflected wave is dissipated in the source resistor.

I have told you time and again that your understanding is
wrong. My claim is that for the special case of a 45 degree
phase difference between the forward wave and reflected wave,
the *average* power in the reflected wave is dissipated in the
source resistor. Irradiance is an *average* power density as
defined by Hecht, in "Optics". I have told you previously (many
times) that when I use the word "power", I am talking about
*average* power. I agree with Hecht that instantaneous power
is "of limited utility" and is therefore mostly irrelevant.

For the record - for the umteenth time: When I say "power", I
am talking about "*average* power". If I ever talk about
instantaneous power, I will say "instantaneous power". If
you still don't understand, you need professional help.

This sentence fragment from your document suggests this:
"reflected energy from the load is flowing through the source
resistor, RS, and is being dissipated there".

I left no doubt as to what I meant in my document. Here is
a quote from the second paragraph in my document:
"Please note that any power referred to in this paper
is an *average power*. Nothing is being asserted or implied about
instantaneous powers. In fact, instantaneous powers are completely
irrelevant to the following discussion."

I simply don't know how to say it any plainer than that.

I really resent your lack of ethics in this matter.
If you are forced to create a Big Lie about what I have
said in order to try to win, is it really worth it?

OK. I think I've got it now.

You are *not* claiming that the *energy* from the reflected wave
is dissipated in the source resistor, because for the *energy*
in the reflected wave to be dissipated in the source resistor,
the *energy* would have to dissipate at the same time that the
reflected wave delivered the *energy*, and the analysis of
instantaneous *energy* flows shows that this is not the case.

Rather, you are saying that the average reflected power is
numerically equal to the increase in the average dissipation
in the source resistor.

I can accept that as correct.

You might consider rewriting the sentence "reflected energy
from the load is flowing through the source resistor, RS, and
is being dissipated there" since it refers to the energy in
the reflected wave and may mislead others in the same way it
mislead me.

...Keith