On Wed, 10 Mar 2004 19:53:20 GMT, Gene Fuller
wrote:

However, don't expect this sort of simple handwaving model to
be extendable to all sorts of silliness about energy and momentum transfer.

It all goes to the measure of Standard handWaving Ridiculousness.

Steve Nosko wrote:
"I disagree." (If part of the source resistance were not lossless
efficiencies would be limited to 50%.)

Before I sent that I asked myself if it were necessary to include the
peoviso that the statement only applies to maximum power transfer. Sez
to myself, no don`t bother. Any schoolboy knows that when the load
resistance is large as compared with the source resistance, you may
exceed 50% efficiency. That`s the norm for power distribution. Also, sez
to myself, the title of the thread is:
" max power transfer theorem"

Surely it`s understood the comments refer to maximum power transfer and
not to a less demanding condition.

Me, myself, and I were wrong.

Best regards, Richard Harrison, KB5WZI

Gene Fuller wrote:
In the perfectly antireflective case all of the waves keep moving in the
same direction, from air to thin film to glass.

To prove that to be a true statement you must prove that the transistion
point between materials of different indices of refraction results in zero
reflections. Good luck on that one.

For instance, one can change the thin-film thickness from 1/4WL to 1/2WL
and cause exactly the opposite effect, i.e. extreme glare.

If you are using the quantum electrodynamics model, please let us know.
Most of the rest of us are using the EM wave reflection model.
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil,

I haven't the foggiest idea what model you might be using. I am using
the classical model that is found in virtually any textbook that deals
with plane waves in non-conducting media.

I don't have to "prove" anything. Just set up the standard wave
equations with the standard boundary conditions and the problem
practically solves itself. The non-zero remaining waves are all moving
in the same direction. I forgot to ask them if they realize that Cecil
doesn't approve of such behavior.

I suppose this is an prime example of being seduced by "math models",
but I believe that is a lesser fault than being seduced by Cecil's
imaginary models.

73,
Gene
W4SZ

Cecil Moore wrote:

Gene Fuller wrote:

In the perfectly antireflective case all of the waves keep moving in
the same direction, from air to thin film to glass.


To prove that to be a true statement you must prove that the transistion
point between materials of different indices of refraction results in zero
reflections. Good luck on that one.

For instance, one can change the thin-film thickness from 1/4WL to 1/2WL
and cause exactly the opposite effect, i.e. extreme glare.

If you are using the quantum electrodynamics model, please let us know.
Most of the rest of us are using the EM wave reflection model.

Richard Harrison wrote:

Cecil, W5DXP wrote:
"It`s not magic and is explained on the Melles-Groit web page---. (how
the energy magically reverses direction and heads back toward the load.)

I agree. It isn`t magic. Optical examples are good because we can see
reflections.

The phenomenon isn't magical, as can be clearly seen in the optics
texts.
On the other hand, Cecil's elaborate theories on the subject transcend
those described within these treatises. Nowhere other than in Cecil's
works will one find a description of waves reversing direction without
reflecting from a discontinuity.

73, Jim AC6XG

Gene Fuller wrote:
In the perfectly antireflective case all of the waves keep moving in the
same direction, from air to thin film to glass.

I just realized what you are saying. Your above statement is wrong about
"all of the waves". Your above statement is correct about "net irradiance".
I'm not talking about "net" anything. I am talking about the component
forward and reflected waves which are easily proven to exist.
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil Moore wrote:

Old Ed wrote:
"Lossless resistance?" Would that be zero resistance,
or perhaps a negative resistance, as in the active part of
a tunnel diode's V-I characteristic?

I am a career EE, with a couple of graduate EE degrees;
and this is something entirely new to me. Could you explain
this concept, and/or provide some references?

How about an example? If L and C are lossless, then SQRT(L/C)
will be lossless with a dimension of ohms, i.e. resistance.

Umm, isn't that an example of reactance? I assume you would have us
believe they are one in the same. BTW, not all forms of resistive loss
are "ohmic".

73, Jim AC6XG
73, Jim AC6XG

Gene Fuller wrote:
I don't have to "prove" anything. Just set up the standard wave
equations with the standard boundary conditions and the problem
practically solves itself. The non-zero remaining waves are all moving
in the same direction. I forgot to ask them if they realize that Cecil
doesn't approve of such behavior.

You should have warned us that you were talking about NET waves and
NET energy transfer. I'm not discussing that at all. I am talking about
component waves and component energy transfer without which standing
waves cannot exist. Or maybe you can offer an example of standing waves
in the absence of at least two waves traveling in opposite directions.
If you can do that, I will admit defeat.

I suppose this is an prime example of being seduced by "math models",
but I believe that is a lesser fault than being seduced by Cecil's
imaginary models.

It is indeed an example of being seduced by the NET math model. Please
transfer over to the component math model and rejoin the discussion.
Lots of interesting things are happening below the threshold of the
NET math model. The NET math model doesn't explain anything except
the NET results. If your bank account balance doesn't change from one
month to another, do you also assume that you have written no checks
and have no income for that month? Literally speaking, please get real!
--
73, Cecil http://www.qsl.net/w5dxp



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Steve Nosko wrote:
"It is as simple as the fact that it is not internally resistance
limited----."

We are discussing maximum power transfer which by definition is the
condition in which all available power is delivered to the load. This
condition requires equal resistances in source and load.

Maximum power transfer can be found by varying the resistance used as
the load until the load resistance is found which generates the most
heat. This assumes there is no reactance or other opposition to power
other than that of the resistive type in the source and load.

Once you`ve found the load which extracts maximum power from the source,
measure its resistance. That is also the resistance of your source.

In the Class-C amplifier, some of the source resistance it presents to
the load is of the lossless variety. Were it all of the dissipative
variety, just as much heat would be generated within the amplifier as
within the load, UNDER MAXIMUM POWER TRANSFER CONDITIONS. Some of the
internal resistance is the lossy kind. The final amplifying devices have
almost full on or off states. There`s little transition, and the
saturation voltage is low but not zero. The lossless variety of internal
resistance comes from an average of the switched-off time of the
amplifier.

My example presumed a 50-50 spllit between dissipative and lossless
resistances in the Class-C amplifier. That made an efficiency of 66.7%.
Not bad and not unusual. That`s the way it works, believe it or not.

Best regards, Richard Harrison, KB5WZI

Jim Kelley wrote:
Nowhere other than in Cecil's
works will one find a description of waves reversing direction without
reflecting from a discontinuity.

You have made that assertion so many times it has turned into a Big Lie.
Maybe you should reveal the agenda responsible for such unethical behavoir?

What I have said is that the *energy* involved in destructive interference
at a Z0-match point reverses direction. The waves are *destroyed* by the
destructive interference and the waves therefore cease to exist. So how could
destroyed waves possibly reverse direction? They cannot! Your assertions are
simply false. Perhaps you are confusing the energy in the cancelled (destroyed)
waves with the waves themselves? In any case, unless I accidentally mis-spoke
sometime, I have never said that cancelled waves reverse themselves. To say
that cancelled waves reverse themselves would be a ridiculous assertion.

The *energy* in the destroyed waves cannot be destroyed and we know that it
doesn't continue on toward the source. Therefore, the *energy* in the
destroyed waves changes directions and becomes constructive interference
flowing toward the load.

The *energy* in the cancelled (destroyed) reflected waves reverses directions
at the Z0-match. There is simply no other possibility since reflected energy
toward the source is eliminated by wave cancellation. All this is explained
on the Melles-Groit web page if you desire to comprehend. They say the "lost"
reflected energy is not lost at all and enhances the forward wave. How can
reflected energy enhance the forward wave without changing directions?
--
73, Cecil http://www.qsl.net/w5dxp



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Jim Kelley wrote:
BTW, not all forms of resistive loss are "ohmic".

The SQRT(L/C) of a lossless transmission line is certainly "ohmic".
Or are you willing to assert that the Z0 of coax is really j50 or
some such. May I suggest a good book on dimensional analysis?
--
73, Cecil http://www.qsl.net/w5dxp



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Jim, AC6XG wrote:
"Ummm, isn`t that an example of reactance?"

Terman on page 88 of his 1955 edition says:
"The characteristic impedance Zo is the ratio of voltage to current in
an individual wave---; it is also the impedance of a line that is
infinitely long or the impedance of a finite length of line when ZL =
Zo. It will be noted that at radio frequencies the characteristic
impedance is a resistance that is independent of frequency."

Isn`t that succinct and beautiful? Wish my thoughts were as clear and
true. We lost a treasure when he passed away.

Best regards, Richard Harrison, KB5WZI

Cecil Moore wrote:

Jim Kelley wrote:
Nowhere other than in Cecil's
works will one find a description of waves reversing direction without
reflecting from a discontinuity.

You have made that assertion so many times it has turned into a Big Lie.
Maybe you should reveal the agenda responsible for such unethical behavoir?

I guess you better reaveal it, because I have no idea what you're trying
to accuse me of.

The *energy* in the cancelled (destroyed) reflected waves reverses directions
at the Z0-match.

You just accused me of lying about your belief in that notion.

73, Jim AC6XG

Cecil Moore wrote:

Jim Kelley wrote:
BTW, not all forms of resistive loss are "ohmic".

The SQRT(L/C) of a lossless transmission line is certainly "ohmic".

You don't seem to know what the term "ohmic" means.

73, Jim AC6XG

Richard Harrison wrote:

Jim, AC6XG wrote:
"Ummm, isn`t that an example of reactance?"

Terman on page 88 of his 1955 edition says:
"The characteristic impedance Zo is the ratio of voltage to current in
an individual wave---; it is also the impedance of a line that is
infinitely long or the impedance of a finite length of line when ZL =
Zo. It will be noted that at radio frequencies the characteristic
impedance is a resistance that is independent of frequency."

Isn`t that succinct and beautiful? Wish my thoughts were as clear and
true. We lost a treasure when he passed away.

Absolutely. If only it were as relevant as it is succinct and
beautiful. But, that's a little out of Terman's hands at this point.
;-)

73, Jim AC6XG

Jim Kelley wrote:
Cecil Moore wrote:
The *energy* in the cancelled (destroyed) reflected waves reverses directions
at the Z0-match.

You just accused me of lying about your belief in that notion.

If you don't understand the difference between saying that cancelled
waves reverse direction and saying that the energy in the cancelled
waves reverses direction, you are beyond help.
--
73, Cecil http://www.qsl.net/w5dxp



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Jim Kelley wrote:

Cecil Moore wrote:
The SQRT(L/C) of a lossless transmission line is certainly "ohmic".

You don't seem to know what the term "ohmic" means.

From the IEEE dictionary: "ohmic contact ... one that has a linear
voltage/current characteristic throughout its entire operating range."
That certainly seems to describe the characteristic impedance of a
transmission line which has a linear voltage/current characteristic
throughout its entire specified operating range even though that Z0
is non-dissipative.

I'm assuming anything with the dimensions of "ohms" is "ohmic" but
I could be wrong. Do you have a reference otherwise?
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil,

Who said anything about distinguishing net waves or component waves? I
was talking about a complete solution.

If you read what I wrote you will note that I said any purported waves
traveling in the reverse direction have zero amplitude. In other words
they do not exist.

If you choose to create any number of fictitious components that all
cancel, go right ahead. No professional does it that way.

You appear to misunderstand that it is essentially impossible to do
anything with all of your interfering component waves except wave your
hands and flap your gums about them. If you really want to get
quantitative answers then it is conventional to use ordinary
electromagnetic theory starting with Maxwell's equations. No fictitious
canceling component waves are needed as input, nor do they arise as
output from a correct analytical treatment.

Really, this is standard textbook stuff. If you would like exact
references by title and page I will be happy to provide them.


73,
Gene
W4SZ

Cecil Moore wrote:
Gene Fuller wrote:

I don't have to "prove" anything. Just set up the standard wave
equations with the standard boundary conditions and the problem
practically solves itself. The non-zero remaining waves are all moving
in the same direction. I forgot to ask them if they realize that Cecil
doesn't approve of such behavior.


You should have warned us that you were talking about NET waves and
NET energy transfer. I'm not discussing that at all. I am talking about
component waves and component energy transfer without which standing
waves cannot exist. Or maybe you can offer an example of standing waves
in the absence of at least two waves traveling in opposite directions.
If you can do that, I will admit defeat.

I suppose this is an prime example of being seduced by "math models",
but I believe that is a lesser fault than being seduced by Cecil's
imaginary models.


It is indeed an example of being seduced by the NET math model. Please
transfer over to the component math model and rejoin the discussion.
Lots of interesting things are happening below the threshold of the
NET math model. The NET math model doesn't explain anything except
the NET results. If your bank account balance doesn't change from one
month to another, do you also assume that you have written no checks
and have no income for that month? Literally speaking, please get real!

Gene Fuller wrote:
If you read what I wrote you will note that I said any purported waves
traveling in the reverse direction have zero amplitude. In other words
they do not exist.

So you disagree with "Wave Mechanics of Transmission Lines, Part 3:"
by S. R. Best, QEX Nov/Dec 2001?

Your statement denies reality. In the following system, 178 joules/sec
are rejected by the load and thus flow back toward the source. You can
measure it with a wattmeter. The very first thing you need to prove is
that standing waves can exist without two waves flowing in opposite
directions. Anything short of that proof is just handwaving and gum
flapping on your part.

278W forward--
100W XMTR---50 ohm feedline---x---1/2WL 450 ohm feedline---50 ohm load
--178W reflected

You appear to misunderstand that it is essentially impossible to do
anything with all of your interfering component waves except wave your
hands and flap your gums about them.

If that is beyond your comprehension, just say so but, in reality, those
interfering component waves obey the laws of physics as explained in _Optics_,
by Hecht and on the Melles-Groit web page:

http://www.mellesgriot.com/products/optics/oc_2_1.htm

"Clearly, if the wavelength of the incident light and the thickness of the
film are such that a phase difference exists between reflections of p, then
REFLECTED WAVEFRONTS INTERFERE DESTRUCTIVELY, and overall reflected intensity
is a minimum. If the TWO REFLECTIONS are of equal amplitude, then this amplitude
(and hence intensity) minimum will be ZERO.

In the absence of absorption or scatter, the principle of CONSERVATION OF
ENERGY indicates all "lost" reflected intensity will appear as ENHANCED
INTENSITY [constructive interference] in the transmitted beam."

That's pretty clear - 100% destructive interference between the two rearward-
traveling reflected wave components - 100% of the energy involved in the destructive
interference is not lost and joins the forward-traveling wave since it has no
other possible direction.

FYI, the equations governing the irradiance involving a perfect non-glare
thin film a Ir1+Ir2-2*SQRT(Ir1*Ir2) = reflected irradiance = 0 and
If1+If2+2*SQRT(If1*If2) = total forward irradiance Page 388 of _Optics_.
--
73, Cecil http://www.qsl.net/w5dxp



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On Tue, 9 Mar 2004 18:34:43 -0600, "Steve Nosko"
wrote:

or is this a troll, Cecil


Hi Steve,

Well - waddaya think?

No. No. The question answers itself in proportion to the chuckles.
Better than video on demand, and cheaper.

73's
Richard Clark, KB7QHC

Cecil, W5DXP wrote:
"I am assuming anything with the dimensions of "ohms" is "ohmic" but I
could be wrong."

That would apply to a transmission line where "The characteristic
impedance Zo is the ratio of voltage to current in an individual
wave;---it is also the impedance of a line that is infinitely long ---"
or terminated in ZL = Zo.

As Reg once noted, you could measure Zo with your ohmmeter in an
infinite line.

Best regards, Richard Harrison, KB5WZI

On Wed, 10 Mar 2004 22:43:11 -0600, Cecil Moore
wrote:

So you disagree with "Wave Mechanics of Transmission Lines, Part 3:"
by S. R. Best, QEX Nov/Dec 2001?

Cecil, are you saying you believe the total nonsense in Steve's Part 3? The
fiction he wrote there is totally incorrect and misleading. He introduced nine
new misconceptions that need dispelling, misconceptions that totally dispute my
explanations of the role of wave mechanics in impedance matching, including my
references from MIT and Harvard EE professors.

I can't disclose what's about to happen in the immediate future on this issue,
but when it does happen you'll see mathematical proof of where herr Best went
wrong. And it also totally supports your argument with Gene, who apparently
doesn't get it either, because I heard him claim that Steve's article is one of
the most illuminating and definitive he's read. Unfortunately, Steve's QEX
article is total BS.

Walt, kW2DU

Richard Harrison wrote:
Cecil, W5DXP wrote:
"I am assuming anything with the dimensions of "ohms" is "ohmic" but I
could be wrong."

As Reg once noted, you could measure Zo with your ohmmeter in an
infinite line.

But some people play semantic games. The IEEE dictionary generally
avoids definitions of adjectives and favors adjectives plus nouns,
e.g. "ohmic contact".

From my physics book, an ohmic conductor is one whose resistivity
is constant with changing voltage. Does "resistivity" imply dissipation?
--
73, Cecil http://www.qsl.net/w5dxp



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As Reg once noted, you could measure Zo with your ohmmeter in an
infinite line.

===========================

It would not be a steady reading on the ohmeter. It would be a quick
deflection followed by a slower subsidence.

Zo of real lines is a function of frequency. As frequency decreases Zo
increases and becomes more reactive ultimately approaching -45 degrees.
This affects in a complex manner the behaviour of the ohmeter pointer.

The ohmeter reading changes from an initial low value to a higher value
versus time. The actual values and time taken depend on Zo and on the
voltmeter resistance. The final value is never achieved just as the final
voltage across a capacitor being charged up via a resistor is never
achieved.

To calculate input resistance versus time as recorded on the ohmeter
requires a large amount of calculation using Heaviside's operational
calculus.

An infinite series of complicated terms is involved. This type of
calculation on transmission lines must have been amongst the very first
carried out by the young Heaviside himself round about 1872. It is closely
related to the distortion of keying waveshapes along telegraph cables.
Imagine the pleasure he experienced, using his own calculus, as he with his
sliderule produced the very first sets of figures and graphs describing the
waveshapes. It is still related to distortion of digital signals in this
modern electronic age but now we have oscilloscopes.
----
Reg, G4FGQ

Walter Maxwell wrote:

Cecil Moore wrote:
So you disagree with "Wave Mechanics of Transmission Lines, Part 3:"
by S. R. Best, QEX Nov/Dec 2001?

Cecil, are you saying you believe the total nonsense in Steve's Part 3?

No, Steve assumes the existence of forward and reflected energy waves.
I also assume the existence of forward and reflected energy waves and
think their existence can be proven. I assume that you agree with Steve
that forward and reflected energy waves exist. If I understand Gene
correctly, he believes that reflected energy waves do not exist in
a matched system even though there is a mismatch at the load.

I probably should have said: "So you disagree with the very existence
of reflected energy waves which is assumed by S. R. Best in his QEX
Nov/Dec 2001 article.

Since Steve's article asserts the existence of forward and reflected
energy waves, it cannot be "total nonsense". In fact, Steve's equation
for total forward power yields the correct answer. In a matched system,

Ptotal = P1 + P2 + 2*SQRT(P1*P2)

indeed yields the correct result given that:

P1 = Psource(1-rho)^2 = Psource times the power transmission coefficient

P2 = Pref(rho)^2 = Preflected times the power reflection coefficient

Steve's problem was that he did not recognize (actually denied) the role
of interference, destructive and constructive, and therefore left out half
of the explanation. In optics, 2*SQRT(P1*P2) is known as the "interference term"
and equal magnitudes of interference happen on both sides of the match point. In
a perfectly matched system, at the match point, there exists total destructive
interference toward the source, i.e. zero reflections, and total constructive
interference toward the load, i.e. all the energy winds up flowing toward the load.

The following two problems are virtually identical. 'n' is the index of
refraction.

air | glass
Laser-------------|---------
n=1.0 | n=1.5

XMTR---50 ohm coax---75 ohm load

The magnitudes of the reflection coefficients are identical at |0.2|

The solutions to those problems are virtually identical.

air | 1/4WL thin-film | glass
Laser-------------|------------------|-----------
n=1.0 | n=1.225 | n=1.5

XMTR---50 ohm coax--x--1/4WL 61.2 ohm coax--75 ohm load

Optical physicists fully understand what happens with the Laser. It is explained
on the Melles-Griot web page and in _Optics_, by Hecht. From the Melles-Griot web
page: http://www.mellesgriot.com/products/optics/oc_2_1.htm

"Clearly, if the wavelength of the incident light and the thickness of the film
are such that a phase difference exists between reflections of p, then reflected
wavefronts interfere destructively, and overall reflected intensity is a minimum.
If the two reflections are of equal amplitude, then this amplitude (and hence intensity)
minimum will be zero. In the absence of absorption or scatter, the principle of conservation
of energy indicates all "lost" reflected intensity will appear as enhanced intensity in the
transmitted beam."

This fits perfectly with Reflections II, chapter 23: "Therefore, while reflection
angles for waves reflected at the input mismatch (point x above) are 180 deg for voltage,
and 0 deg for current, the corresponding angles at the input for the waves reflected
from the output mismatch (75 ohm load above) are reversed, 0 deg for voltage and 180
deg for current. Consequently, all corresponding voltage and current phasors are 180
deg out of phase at the matching point. ... With equal magnitudes and opposite phase
at the same point (point x, the matching point) the sum of the two waves is zero."

That is a perfect description of total destructive interference. I have your reference,
J. C. Slater's book, _Microwave_Transmission_, on order.
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil, W5DXP wrote:
"Does "resistivity" imply dissipation?"

I haven`t looked it up but the word "resistivity" automatically
generates a definition in my mind:

Rho = length / area.

Best regards, Richard Harrison, KB5WZI

On Thu, 11 Mar 2004 09:52:28 -0600, Cecil Moore
wrote:

Walter Maxwell wrote:

Cecil Moore wrote:
So you disagree with "Wave Mechanics of Transmission Lines, Part 3:"
by S. R. Best, QEX Nov/Dec 2001?

Cecil, are you saying you believe the total nonsense in Steve's Part 3?

No, Steve assumes the existence of forward and reflected energy waves.
I also assume the existence of forward and reflected energy waves and
think their existence can be proven. I assume that you agree with Steve
that forward and reflected energy waves exist. If I understand Gene
correctly, he believes that reflected energy waves do not exist in
a matched system even though there is a mismatch at the load.

I probably should have said: "So you disagree with the very existence
of reflected energy waves which is assumed by S. R. Best in his QEX
Nov/Dec 2001 article.

Cecil, it's not whether reflected waves exist that's wrong with Steve's paper,
it's his misuse them that's wrong, and it's the misuse that is 'total nonsense'.

Since Steve's article asserts the existence of forward and reflected
energy waves, it cannot be "total nonsense". In fact, Steve's equation
for total forward power yields the correct answer. In a matched system,

Ptotal = P1 + P2 + 2*SQRT(P1*P2)

indeed yields the correct result given that:

P1 = Psource(1-rho)^2 = Psource times the power transmission coefficient

P2 = Pref(rho)^2 = Preflected times the power reflection coefficient

Cecil, your equations for P1 and P2 yield absurd answers if you plug the numbers
into them. The value for P1 should read "Psource (1 - rho^2) = ..., and the
value for P2 should read "P2 = Pref (rho^2). Beega difference! Then the value
for Ptotal will be correct.

Steve's problem was that he did not recognize (actually denied) the role
of interference, destructive and constructive, and therefore left out half
of the explanation.

Exactly!!! And it's the correct interference relationship I present in QEX and
Reflections that he insists is incorrect. In much earlier emails with Steve he
told me that using my statements appearing there he could prove me technically
incompetent. He simply would not accept any of my pleadings with him to see the
correct application of the interference between reflected waves that achieves
the impedance match.

In optics, 2*SQRT(P1*P2) is known as the "interference term"
and equal magnitudes of interference happen on both sides of the match point. In
a perfectly matched system, at the match point, there exists total destructive
interference toward the source, i.e. zero reflections, and total constructive
interference toward the load, i.e. all the energy winds up flowing toward the load.

The following two problems are virtually identical. 'n' is the index of
refraction.

air | glass
Laser-------------|---------
n=1.0 | n=1.5

XMTR---50 ohm coax---75 ohm load

The magnitudes of the reflection coefficients are identical at |0.2|

The solutions to those problems are virtually identical.

air | 1/4WL thin-film | glass
Laser-------------|------------------|-----------
n=1.0 | n=1.225 | n=1.5

XMTR---50 ohm coax--x--1/4WL 61.2 ohm coax--75 ohm load

Optical physicists fully understand what happens with the Laser. It is explained
on the Melles-Griot web page and in _Optics_, by Hecht. From the Melles-Griot web
page: http://www.mellesgriot.com/products/optics/oc_2_1.htm

"Clearly, if the wavelength of the incident light and the thickness of the film
are such that a phase difference exists between reflections of p, then reflected
wavefronts interfere destructively, and overall reflected intensity is a minimum.
If the two reflections are of equal amplitude, then this amplitude (and hence intensity)
minimum will be zero. In the absence of absorption or scatter, the principle of conservation
of energy indicates all "lost" reflected intensity will appear as enhanced intensity in the
transmitted beam."

No one in his right mind can successfully argue against this. Anyone who would
argue against this is either of closed mind or an ignorant moron.

This fits perfectly with Reflections II, chapter 23: "Therefore, while reflection
angles for waves reflected at the input mismatch (point x above) are 180 deg for voltage,
and 0 deg for current, the corresponding angles at the input for the waves reflected
from the output mismatch (75 ohm load above) are reversed, 0 deg for voltage and 180
deg for current. Consequently, all corresponding voltage and current phasors are 180
deg out of phase at the matching point. ... With equal magnitudes and opposite phase
at the same point (point x, the matching point) the sum of the two waves is zero."

I'm glad you find that Chapter 23 fits, because I've known all along that it
fits perfectly with Melles-Griot. Steve (Best), on the other hand says Chapter
23 is totally wrong. You might also note that Chapter 23 is identical with my
paper in QEX in the Mar/Apr 1998 issue, which Steve also disputes in all three
parts of his QEX article.

That is a perfect description of total destructive interference. I have your reference,
J. C. Slater's book, _Microwave_Transmission_, on order.

You might find Slater (1943) difficult to obtain. I can email you a copy of the
pertinent part if you wish.

Walt, W2DU

In all these sort of discussions I have never heard any mention of
"Interaction Loss", ie., that which occurs directly between the reflection
coefficients of the source and load.

It seems something important has long been and is still being neglected. It
may be that some points of dispute could be resolved by taking Interaction
Loss into account.
----
Reg.

Walter Maxwell wrote:
Cecil, your equations for P1 and P2 yield absurd answers if you plug the numbers
into them. The value for P1 should read "Psource (1 - rho^2) = ..., and the
value for P2 should read "P2 = Pref (rho^2). Beega difference! Then the value
for Ptotal will be correct.

Yep, Walt, I made a typo. It should be (1-rho^2). When I think in words while
typing, "one minus rho squared", is ambiguous. Obviously (rho)^2 + (1-rho^2)
*must* equal unity, i.e. the total.

I'm glad you find that Chapter 23 fits, because I've known all along that it
fits perfectly with Melles-Griot. Steve (Best), on the other hand says Chapter
23 is totally wrong.

I don't know how he can say that. The Melles-Griot data for perfect non-glare
glass depends upon two 'I' irradiance equations.

Irradiance toward the source (reflected irradiance) equals:

Ir1 + Ir2 - 2*(Ir1*Ir2) = 0 = Ir1 + Ir2 - total_destructive_interference

Irradiance toward the load (total forward irradiance) equals:

If1 + If2 + 2*(If1*If2) = If1 + If2 + total_constructive_interference

It may not be apparent but (Ir1*Ir2) *must* equal (If1*If2).

Steve and I had an argument about this stuff years ago before he published his
QEX article. He denied that any interference exists even though his 2*SQRT(P1*P2)
term is know as the "interference term".

Irradiance, 'I', for a laser beam, is equivalent to power. Reflectance, 'R' in optics, is
the power reflection coefficient. Transmittance, 'T' in optics, is the power transmission
coefficient. Thus:

Ir1 = R*Isource Ir2 = T*Iref If1 = T*Isource If2 = R*Iref

You might find Slater (1943) difficult to obtain. I can email you a copy of the
pertinent part if you wish.

Thanks, but my used copy has already shipped through http://www.powellsbooks.com

Walt, as you know, QEX refused to publish my rebuttal of Steve's article. There's
some good stuff and some bad stuff in his article. This is not a black and white
argument. IMO, about a third of Steve's Part 3 article is valid. My objections
are with the other 2/3.
--
73, Cecil http://www.qsl.net/w5dxp



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Reg Edwards wrote:
In all these sort of discussions I have never heard any mention of
"Interaction Loss", ie., that which occurs directly between the reflection
coefficients of the source and load.

It seems something important has long been and is still being neglected. It
may be that some points of dispute could be resolved by taking Interaction
Loss into account.

We usually discuss Z0-matched systems. In a Z0-matched system,
the reflection coefficients at the two reflection points are
equal in magnitude and opposite in sign. If no reflections are
allowed to reach the source, there is zero "Interaction Loss".
--
73, Cecil, W5DXP

Dave Shrader has kindly contacted me to tell me I was wrong with my
resistivity definition.

Dave is right.

The formula I was trying to remember is:

Resistance = RESISTIVITY x length / area

I goofed and I`m sorry.

Best regards, Richard Harrison, KB5WZI

"Gene Fuller" wrote in message
...
Cecil,
You appear to misunderstand that it is essentially impossible to do
anything with all of your interfering component waves except wave your
hands and flap your gums about them.

you must be new here... that is what these guys do all day long!

Hi Walt,

I am quite surprised and disappointed that you commented on my review of
Steve Best's QEX articles in the manner quoted he

On Thu, 11 Mar 2004 09:17 Walter Maxwell wrote:

And it also totally supports your argument with Gene, who apparently
doesn't get it either, because I heard him claim that Steve's article is one of
the most illuminating and definitive he's read. Unfortunately, Steve's QEX
article is total BS.

Walt, kW2DU

************************************************** *

Here is an exact quote from my email to you dated January 31, 2003.

Hi Walt,

I'm back.

I have re-read the Best QEX article, I have read your rebuttal
carefully, and I have re-read parts of Reflections II.

I have to say that I believe the QEX article in question is fair and
correct. I cannot find a single flaw in it.

I have documented my response by adding comments to the rebuttal draft
you sent me the other day. My comments are in red.

In summary, I think the QEX article is completely correct in items 1, 2,
and 3. I am less comfortable about making any sort of definitive
statement on item 4.

I have been aware of the controversy for some time, and I am somewhat
dumbfounded by the entire matter.

I tacitly believed that all of this stuff had been fully defined,
understood, and non-controversial for many decades. Certainly there is
no new science in classical transmission line theory in 2003.

To the best of my understanding this entire matter has somewhat the
character of a tempest in a teapot. I have not found the slightest
evidence that your model and Steve Best's model disagree in any
measurable way. Clearly the insides of the models are different, but the
visible, measurable parts are not.

Is there a single case in which Best's model gives the wrong answer by
any measurement technique?

Is there a single case in which your model gives the wrong answer by any
measurement technique?

From a visualization and conceptualization point the models are quite
different. You note that many engineers appreciate your model as it
provides them a good understanding of the reflection behavior. To be
brutally honest, I prefer the approach taken by Best. I like the
equations to balance explicitly, and I am less comfortable with relying
on concepts like virtual opens and shorts.

Again, I do not see any physically measurable difference in the output
from the models. The rest is philosophy.

snip of irrelevant pleasantries

************************************************** *

Soooo, Walt, what did I write that elicited your unkind comment?


73,
Gene
W4SZ

Cecil,

OK, I will 'see' your references and 'raise' my bid to Born and Wolf
"Principles of Optics", 7th edition.

I recommend section 1.6, "Wave propagation in a stratified medium.
Theory of dielectric films". This section runs from page 54 to page 74,
and it describes in full detail everything you would want to know about
propagation of waves in multilayered structures.

There is a disclaimer in the introduction to this section which says,
"For the treatment of problems involving only a small number of films it
is naturally not necessary to use the general theory, and accordingly we
shall later describe an alternative and older method based on the
concept of multiple reflections." The reference is to section 7.6
"Multiple-beam interference", which runs from page 359 to page 409.

Similar sections are included in the 6th edition of this book, on pages
51 to 70 and 323 to 367 respectively. I am sure you can find one or both
of these editions in the TAMU library. I prefer the 7th edition, as it
seems easier on the eyes.

If you choose not to actually read these references I will tell you that
the first section is a full-blown Maxwell's equations treatment, and the
second section employs an interfering wave treatment.

What I find interesting is that there is not one mention of bouncing
energy waves or waves that have disappeared but their energy lives on.
If you read your favorite Melles-Griot material carefully without adding
your own spin (how else could it be, etc.) you will see that they do not
discuss bouncing energy waves either. You will notice that M-G say the
energy "appears" in the transmitted wave. This is good, since we like to
believe conservation of energy is maintained. M-G do not discuss the
mechanism. All of the stuff about bouncing energy rejoining the forward
wave is purely in your imagination.

I think I have finally figured out the root of the disagreement. Your
approach is similar to a one-trick pony. You have latched onto the
concept of interference to the exclusion of any other valid approach. As
a consequence it becomes *necessary* to imagine such things as bouncing
energy waves. The Maxwell's equations approach does not require this
sort of crutch. Try it, you might like it.

I am quite familiar with both analytical methods, and I am comfortable
in using either one. The key is understanding when a given analytical
technique will be the most useful, most direct, most intuitive, and so
on. I have nothing against interference, but its misapplication is like
using a pipe wrench to drive a nail while a hammer is right at hand.

73,
Gene
W4SZ



Cecil Moore wrote:



If that is beyond your comprehension, just say so but, in reality, those
interfering component waves obey the laws of physics as explained in
_Optics_, by Hecht and on the Melles-Groit web page:

http://www.mellesgriot.com/products/optics/oc_2_1.htm

On Fri, 12 Mar 2004 03:51:35 GMT, Gene Fuller
wrote:

The Maxwell's equations approach does not require this
sort of crutch. Try it, you might like it.

Hi Gene,

It's not about being correct, it's about "truth" and proving the great
satan Steve wrong. When you've been flashed fried, facts don't
matter anymore. ;-)

73's
Richard Clark, KB7QHC

On Fri, 12 Mar 2004 03:51:35 GMT, Gene Fuller wrote:

Cecil,

OK, I will 'see' your references and 'raise' my bid to Born and Wolf
"Principles of Optics", 7th edition.

I recommend section 1.6, "Wave propagation in a stratified medium.
Theory of dielectric films". This section runs from page 54 to page 74,
and it describes in full detail everything you would want to know about
propagation of waves in multilayered structures.

There is a disclaimer in the introduction to this section which says,
"For the treatment of problems involving only a small number of films it
is naturally not necessary to use the general theory, and accordingly we
shall later describe an alternative and older method based on the
concept of multiple reflections." The reference is to section 7.6
"Multiple-beam interference", which runs from page 359 to page 409.

Well, Gene, you apparently deny that 'bouncing' waves exist. So what exactly are
'multiple reflections'?

Similar sections are included in the 6th edition of this book, on pages
51 to 70 and 323 to 367 respectively. I am sure you can find one or both
of these editions in the TAMU library. I prefer the 7th edition, as it
seems easier on the eyes.

If you choose not to actually read these references I will tell you that
the first section is a full-blown Maxwell's equations treatment, and the
second section employs an interfering wave treatment.

So I now ask, if your selected reference discusses interfering wave treatment
and multiple reflections in the explanation of impedance matching, then why do
you consider Cecil's position concerning reflected energy joining the forward
wave as purely in his imagination? Seems as if you're wearing opaque glasses
backward.

What I find interesting is that there is not one mention of bouncing
energy waves or waves that have disappeared but their energy lives on.
If you read your favorite Melles-Griot material carefully without adding
your own spin (how else could it be, etc.) you will see that they do not
discuss bouncing energy waves either. You will notice that M-G say the
energy "appears" in the transmitted wave. This is good, since we like to
believe conservation of energy is maintained. M-G do not discuss the
mechanism. All of the stuff about bouncing energy rejoining the forward
wave is purely in your imagination.

Imagination, indeed!

I think I have finally figured out the root of the disagreement. Your
approach is similar to a one-trick pony. You have latched onto the
concept of interference to the exclusion of any other valid approach. As
a consequence it becomes *necessary* to imagine such things as bouncing
energy waves. The Maxwell's equations approach does not require this
sort of crutch. Try it, you might like it.

Gene, multiple reflections in wave mechanics are the basic tools that accomplish
impedance matching--no way are the reflected waves any sort of a crutch. There
can be NO matching of different impedances without reflections. How could there
not be reflections when electromagnetic waves encounter a diffferent impedance
when going from medium to another?

I am quite familiar with both analytical methods, and I am comfortable
in using either one. The key is understanding when a given analytical
technique will be the most useful, most direct, most intuitive, and so
on. I have nothing against interference, but its misapplication is like
using a pipe wrench to drive a nail while a hammer is right at hand.

Wave interference is the total basis for all impedance-matching operations.
There is no misapplication of wave interference, and your assertion that the
pipe wrench and hammer apply here is absurd.

If you have a copy of QEX for Mar/Apr 1998 please review an article there
concerning this subject. It just might give you the opportunity of looking at
the concept from a somewhat different perspective.

Walt, W2DU

Gene Fuller wrote:
If you choose not to actually read these references I will tell you that
the first section is a full-blown Maxwell's equations treatment, and the
second section employs an interfering wave treatment.

Everyone already knows the end results so Maxwell's equations offer no
clues as to what actually happens in reality in the process of
yielding those results. The interfering wave treatment is the only one,
to the best of my knowledge, that yields clues as to the physical events
involved. What happens has to obey the laws of physics including the laws
of interference and conservation of energy and momentum.

What I find interesting is that there is not one mention of bouncing
energy waves or waves that have disappeared but their energy lives on.

Gene, neither have I ever said anything about "bouncing waves". That is entirely
a diversionary invention of yours. I have talked about reflected waves, Dr. Best
has talked about reflected waves, and the Melles-Griot web page also talks about
reflected waves. You are on record as asserting that reflected waves don't exist
thus disagreeing with Melles-Griot. Have you ever used a TDR?

If you read your favorite Melles-Griot material carefully without adding
your own spin (how else could it be, etc.) you will see that they do not
discuss bouncing energy waves either.

Neither have I ever discussed "bouncing energy waves". That is your very
own diversion from subject matter that you are apparently loathe to discuss.
The Melles-Griot web page indeed does discuss destructive interference between
two rearward-traveling reflected waves, the "lost" energy of which, winds up
traveling in the forward direction toward the load.

You will notice that M-G say the energy "appears" in the transmitted wave.

Is that anything like angels appearing to the Virgin Mary? :-)
"Appears", in the M-G context means "coherently joins".

How does the "lost" energy from two interfering rearward-traveling waves
appear in the forward-traveling transmitted wave energy without changing
direction? Please don't just ignore that question.

Dr. Best dismissed the rearward-traveling energy and simply magically re-
introduced it into the forward wave. Do you also believe in magic? Dr. Best
also denied that interference had anything to do with matching when, in reality,
interference has everything to do with matching. A Z0-match point in a
feedline with reflections is impossible without interference.

Why didn't you object to Dr. Best's use of "bouncing waves"? Here's a quote
from his article: "When the system reaches the steady state, the two rearward-
traveling waves at the match point are 180 degrees out of phase with respect
to each other and a complete cancellation of both waves occurs."

That is a true statement and Melles-Griot and I have said exactly the same thing.
The question is: What happens to the energy in those cancelled waves? It doesn't
continue on toward the source. It doesn't stand still. It is not destroyed. Can
you guess what happens to it? Melles-Griot says it appears in the forward wave.
Do you think "appears" is a magic word? Can energy suddenly appear from nowhere?

Hecht in _Optics_ tells us that added constructive interference energy always
originates from and is equal in magnitude to the lost destructive interference
energy. Anything else violates the conservation of energy principle. The
answer is obvious. Destructive interference energy left over from the
cancellation of two rearward-traveling reflected waves changes direction
and appears in the forward wave. There is simply no where else for it to go.

I think I have finally figured out the root of the disagreement. Your
approach is similar to a one-trick pony. You have latched onto the
concept of interference to the exclusion of any other valid approach.

Nope, I'm open for any other valid approach but nobody has furnished another
one so far. I'm not interested in net answers. I'm interested in explaining
the physical process within the accepted laws of physics. No magic or steady
state short cuts accepted.
--
73, Cecil http://www.qsl.net/w5dxp



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Richard Clark wrote:

Gene Fuller wrote:
The Maxwell's equations approach does not require this
sort of crutch. Try it, you might like it.

It's not about being correct, it's about "truth" and proving the great
satan Steve wrong. When you've been flashed fried, facts don't
matter anymore. ;-)

Maxwell's equations yield answers but give no clue as to the
detailed physical process involved. Since everyone already
knows the answers, Maxwell's equations are no help at all
in explaining the 1, 2, 3, ... step-by-step process.

Here's a quote from Steve's article: "When the system reaches the
steady state, the two rearward-traveling waves at the match point
are 180 degrees out of phase with respect to each other and a complete
cancellation of both waves occurs."

I agree with that statement. But when I ask what happens to the energy
in those two cancelled waves, all I get is silence. So Richard, what
happens to the energy in those two cancelled waves? Destroyed? Bleeds
off to a parallel universe? Routed through a black hole for constructive
interference in the opposite direction? The answer is more than obvious.
Maxwell's equations tell us that all the energy in a Z0-matched system
winds up incident upon the load. That necessarily includes all the
energy in the rearward-traveling cancelled waves.
--
73, Cecil http://www.qsl.net/w5dxp



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On Thu, 11 Mar 2004 23:26:43 -0600, Cecil Moore
wrote:

Maxwell's equations yield answers but give no clue as to the
detailed physical process involved.

Clueless, hmm?

Since everyone already knows the answers,

All the answers and no clues, even more curious.

Maxwell's equations are no help at all
in explaining the 1, 2, 3, ... step-by-step process.

You got more problems than clues and answers.

Here's a quote from Steve's article

Ah, the great satan having been invoked. How'd I peg that so square
on the head?


I agree with that statement. But when I ask what happens to the energy
in those two cancelled waves, all I get is silence.

That's all it merits,

So Richard, what
happens to the energy in those two cancelled waves? Destroyed? Bleeds
off to a parallel universe? Routed through a black hole for constructive
interference in the opposite direction? The answer is more than obvious.

From those three alternatives drawn from a hat? Three card monte is a
more honest game. You forgot the part about truth, justice and the
american way....

Maxwell's equations tell us ...

And here you told us that maxwell's equations were clueless, answers
that described nothing and no help at all - unless they pass through
your model.

Well, I did say this was more entertaining than video on demand.
Lower bandwidth too.

73's
Richard Clark, KB7QHC

Regardless of impedances, with a sensibly zero-loss line it's quite obvious
ALL the power leaving the generator is dissipated in the load. There's
nowhere else for the stuff to go.

If any power is NOT dissipated in the load due to any cause then it never
leaves the generator.

What on earth have bouncing waves, virtual this that and the other got to do
with it.
----
Reg, G4FGQ