Analyzing Stub Matching with Reflection Coefficients
 

Gene Fuller wrote:
Where are the equations that describe this "delta-t" stuff that you keep
bringing up?

delta-t is a mathematical term, Gene, related in the limit
to the differential dt. If you have to ask, I'm sure you
wouldn't understand the explanation.

Given the following experiment with two signal generators
equipped with circulators and load resistors - the generators
are phased-locked to ensure coherency:

100W 50W
50 ohm---50 ohm line---+---291.4 ohm line---291.4 ohm
SGCL1 SGCL2

Here's the setup for determining s11 and s21 with
SGCL2 turned off.

100W
50 ohm---50 ohm line---+---291.4 ohm line---291.4 ohm load
SGCL1

Here are the results:

a1----|
|----s21(a1)
s11(a1)----|

THE EM WAVE, s11(a1), EXISTS, IS MEASURABLE, AND IS ALIVE
AND WELL.

Here's the setup for determining s12 and s22 with
SGCL1 turned off.

50W
50 ohm load---50 ohm line---+---291.4 ohm line---291.4 ohm
SGCL2

Here are the results:

|----s22(a2)
s12(a2)----|
|----a2

THE EM WAVE, s12(a2), EXISTS, IS MEASURABLE, AND IS ALIVE
AND WELL.

Now power off both signal generators and power them up
simultaneously. Let t=0 be the time when s11(a1) and
s12(a2) first exist. Superpose s11(a1) and s12(a2). How
long does it take to achieve b1 = s11(a1) + s12(a2) = 0?
I estimate that time to be delta-t which becomes dt
in the differential equation limit.

The principle of superposition allows us to observe that
s11(a1) and a12(a2) actually existed before they were
canceled.
--
73, Cecil http://www.w5dxp.com

Analyzing Stub Matching with Reflection Coefficients
 

Roy Lewallen wrote:
I think you've put your finger right on Cecil's conceptual problem.

Your conceptual problem is obviously that you don't
understand the difference between a DC circuit problem
and an RF distributed network problem.

Can you get DC current to flow in opposite directions
around a closed loop? Can you get RF current to flow
in opposite directions around a closed loop.

Please get real.
--
73, Cecil http://www.w5dxp.com

Analyzing Stub Matching with Reflection Coefficients
 

Gene Fuller wrote:
Where are the equations that describe this "delta-t" stuff that you keep
bringing up?

I made an error in my last reply and have canceled that reply.

delta-t is a mathematical term, Gene, related in the limit
to the differential dt. If you have to ask, I'm sure you
wouldn't understand the explanation.

Given the following experiment with two signal generators
equipped with circulators and load resistors - the generators
are phased-locked to ensure coherency:

100W 100W
50 ohm---50 ohm line---+---291.4 ohm line---291.4 ohm
SGCL1 SGCL2

Here's the setup for determining s11 and s21 with
SGCL2 turned off.

100W
50 ohm---50 ohm line---+---291.4 ohm line---291.4 ohm load
SGCL1

Here are the results:

a1----|
|----s21(a1)
s11(a1)----|

THE EM WAVE, s11(a1), EXISTS, IS MEASURABLE, AND IS ALIVE
AND WELL.

Here's the setup for determining s12 and s22 with
SGCL1 turned off.

100W
50 ohm load---50 ohm line---+---291.4 ohm line---291.4 ohm
SGCL2

Here are the results:

|----s22(a2)
s12(a2)----|
|----a2

THE EM WAVE, s12(a2), EXISTS, IS MEASURABLE, AND IS ALIVE
AND WELL.

Now power off both signal generators and power them up
simultaneously. Let t=0 be the time when s11(a1) and
s12(a2) first exist. Superpose s11(a1) and s12(a2). How
long does it take to achieve b1 = s11(a1) + s12(a2) = 0?
I estimate that time to be delta-t which becomes dt
in the differential equation limit.

The principle of superposition allows us to observe that
s11(a1) and a12(a2) actually existed before they were
canceled.
--
73, Cecil http://www.w5dxp.com

Analyzing Stub Matching with Reflection Coefficients
 

Gene Fuller wrote:
I am familiar with all sorts of weird and wonderful things that happen
on surfaces and really close to interfaces and discontinuities.

Here's a little brain teaser for you, Gene.

Given the following experiment with two signal generators
equipped with circulators and load resistors - the generators
are phased-locked to ensure coherency. The two feedlines
are of equal electrical lengths.

100W | 25W
50 ohm---50 ohm line---+---291.4 ohm line---291.4 ohm
SGCL1 Pfor1=100W-- | --Prev2=25W SGCL2
--Prev1 | Pfor2--

What is the magnitude of Prev1? Pfor2?
--
73, Cecil http://www.w5dxp.com

Analyzing Stub Matching with Reflection Coefficients
 

Roy Lewallen wrote:
I think you've put your finger right on Cecil's conceptual problem. When
we solve the battery example by superposition, we get the right answer,
zero current. But now let's put a resistor between the two batteries and
repeat the solution. When we "turn off" the left hand battery, we have a
lot of power being dissipated in that resistor. Using Cecil's view, we
would assign this to be the power associated with the current flowing to
the left. Then we "turn on" the left hand battery and "turn off" the
right hand battery. Again we have a lot of power being dissipated. This
would be the power associated with the current flowing to the right. The
problem comes in having to somehow manipulate these powers to get zero,
which is what we actually see. The mistake, as you continually point
out, is attributing a power to each current -- or each wave -- in the
first place.

Roy, the intensity equation from the field of optics actually
handles that situation perfectly. The batteries are hooked
up in opposition to each other. Mathematically, their voltages
are 180 degrees out of phase.

Let P1 be the power dissipated in the resistor when battery
#1 is on. Let P2 be the power dissipated in the resistor
when battery #2 is on. P1 = P2

When both batteries are on, the total power in the resistor is:

Ptot = P1 + P2 + SQRT(P1*P2)cos(180) = 0

The intensity equation gets the same total power as you do. If
it's wrong then you are wrong. If it's right then you are wrong.
Seems that you are wrong either way. :-)
--
73, Cecil http://www.w5dxp.com

Analyzing Stub Matching with Reflection Coefficients
 

On Apr 19, 11:57 pm, Cecil Moore wrote:
Keith Dysart wrote:
Minor changes to the generator for B can give you a very hot one
or one that is exactly the same temperature as the one with
the circulator.

You've been hammering people with the source of your choice
for days but choose to abandon it as soon as someone points out
a logical problem with it.

Yes indeed. But a key realization is that the behaviour on the line
can not depend on arcane details about the construction of the
generator. So when such statements are made, it is instructive
to explore the situation with a different generator. If the outcome
is different, then there is something wrong with the theory. Note
that the standard explanations only require that the impedance
of the source be known. It is not important how this impedance
is achieved. With the hypothesis you are proposing, the internal
details significantly change the behaviour on the line and require
that the line (or the wave) know the internals so that it can
decide to enter or reflect despite the impedance being the same.

The conditions on the lines are indistinguishable and yet you
claim one is reflecting and one is not. How did the line know
whether it should reflect or not? Or is the wave that knows?

One wave encounters a 50 ohm resistor and is dissipated.
The other wave encounters an infinite impedance and is
100% re-reflected - all in accordance with the wave
reflection model.

But how does it know, since the output (source) impedances are
the same for both cases? How does the 50 Ohm output
impedance of generator B become infinite while the 50 Ohm
output impedance of generator A does not? This is the key
issue with your explanation. In fact, there is no difference and
they behave the same. The reverse wave encounters 50 Ohms
and is not reflected in either case. It is the only sensible answer.

Actually Pnet is zero because of basic circuit theory and the
universally accepted understanding that P = VI.

Circuit theory completely falls apart with distributed
network problems. The currents at two points in the
closed loop are often flowing in opposite directions.

This is a misunderstanding. Look at the distributed inductors and
capacitors and make the measurements at a point that makes
sense. This is, of course, how a directional wattmeter works.
It measures the voltage and current at one place on the line.
And this is how a real wattmeter would work if it was placed
at the same point.

In circuits, we measure the power at a particular place.
I certainly want my power company to do this. If the voltage
or current is 0 at a particular place in the circuit then no
energy is flowing at that place in the circuit. If you are disputing
this, I contend that you do not accept that P = VI.

Plenty of energy is flowing - two equal magnitudes
in opposite directions equals zero net energy.

Correction to your P = VI based on DC, not AC/RF:

Net P = V*I*cos(theta) = Pfor - Pref

I think you have made this mistakte before. In my expression P=VI,
V and I are simultaneous instantaneous values and P is the
instantaneous power. If you want average you need to integrate
and divide.

Your expression applies only to sine waves and V and I are peak
voltages. Interestingly, the expression P=V*I*cos(theta) for sine
waves is always derived by starting with Pinst=Vinst*Iinst,
substituting the appropriate functions for Vinst and Inst, integrating
and dividing.

Forget V and I being 0. cos(theta) is always 0 for a
standing wave. There is ZERO net power anywhere in a
standing wave. (It's a lot like my bank account.)

True. But there IS energy flowing at every point that is not a voltage
minimum or maximum. At these points there is NEVER any energy
flowing.

Inventive. But it doesn't fly. P = VI or it doesn't.

Forward waves and reflected waves are completely independent
of each other and do NOT interact. Their powers do NOT
superpose. There is nothing but joules moving at the
speed of light in a transmission line. There's no net
energy but your zero energy assertions are just illusions.
EM waves are incompatible with zero energy.

Well that does leave you with a bit of a conundrum since on
an open ended line, zero energy is flowing at every quarter
wavelength point back from the load. Pinst=Vinst*Iinst.
Vinst or Iinst is for all times zero. Power must be zero for
all times.

At such a point a real instantaneous wattmeter would always
indicate zero. At other points a real wattmeter would show
energy flowing first one way then the other, though the average
would be zero. And the peak magnitude of the energy flow
depends on where you insert the real wattmeter on the line.
An instructive question: Where does the peak energy flow
occur? It is zero at every quarter wavelength point so it
must be highest somewhere else.

....Keith

Analyzing Stub Matching with Reflection Coefficients
 

On Apr 20, 12:23 am, Cecil Moore wrote:
Roy Lewallen wrote:
I think you've put your finger right on Cecil's conceptual problem.

Your conceptual problem is obviously that you don't
understand the difference between a DC circuit problem
and an RF distributed network problem.

Can you get DC current to flow in opposite directions
around a closed loop? Can you get RF current to flow
in opposite directions around a closed loop.

However when you draw the distributed elements, you find
there are many loops (an infinite number?) and each loop
behaves exactly as it does for those in a circuit built of
lumped elements. There is no magic at all. The same
theories work, though the calculus is a bit more tedious.

So the RF is not flowing in opposite directions around the
loop. You just have not drawn the appropriate loops.

....Keith

Analyzing Stub Matching with Reflection Coefficients
 

On Apr 20, 1:02 am, Cecil Moore wrote:
When both batteries are on, the total power in the resistor is:

Ptot = P1 + P2 + SQRT(P1*P2)cos(180) = 0

The intensity equation gets the same total power as you do. If
it's wrong then you are wrong. If it's right then you are wrong.
Seems that you are wrong either way. :-)

The difficulties with your explanations are not so much that they
give you the wrong numerical answers. In fact, they give you the
right numerical answers so often that they convince you of their
truth.

No, the problem is that they lead you to do other thinks wrong.

For example, in all your examples you now provide a circulator
because you think this is the only way to control reflections,
when in fact, all that is necessary is a source impedance that is
equivalent to the line impedance and there will be no reflection.

In other cases you claim that problems are insolvable because
insufficient information is provided about the generator. In fact,
all you need to do is use the source impedance to compute
the reflection coefficient and the problem is solved.

You claim that superposition does not work in a generator.

These examples are suboptimal outcomes that derive
from your explanations. Better explanations do not lead to
these limitations.

Of course, you keep providing examples where the numbers
work and these reinforce your beliefs. You need to temporarily
let go and explore the alternatives. You will find that the
alternatives work better, not because they necessarily
give you different numerical answers but because they free
you to solve more problems and provide more optimal solutions.

....Keith

Analyzing Stub Matching with Reflection Coefficients
 

Keith Dysart wrote:
But a key realization is that the behaviour on the line
can not depend on arcane details about the construction of the
generator.

Agreed, but the behavior on the line also doesn't depend
upon where the forward and reverse traveling wave came from.
All that is important is their existence. The reverse
traveling wave might come from a separate source and the
line doesn't know the difference.

So when such statements are made, it is instructive
to explore the situation with a different generator. If the outcome
is different, then there is something wrong with the theory.

No, if the outcome is different, something different is
happening while abiding by the wave reflection model rules.
Why are you surprised that changes occur when something is
changed?

Note
that the standard explanations only require that the impedance
of the source be known.

If the "standard explanations" were correct, this would
have been put to bed a long time ago.

But how does it know, since the output (source) impedances are
the same for both cases?

Conclusion: The output source impedance is NOT the impedance
encountered by the reflected wave. That's essentially what
Walter Maxwell's paper says.

I think you have made this mistakte before. In my expression P=VI,
V and I are simultaneous instantaneous values and P is the
instantaneous power. If you want average you need to integrate
and divide.

No, if you want to average sinusoidals , use RMS values, which
is the result of said integrating and dividing. Somebody else
already did all the work.

Your expression applies only to sine waves and V and I are peak
voltages.

I is a peak voltage??????? You are more confused than
I ever realized. :-)

Interestingly, the expression P=V*I*cos(theta) for sine
waves is always derived by starting with Pinst=Vinst*Iinst,

Interestingly, you forgot to say you were talking about
instantaneous power until now.

True. But there IS energy flowing at every point that is not a voltage
minimum or maximum. At these points there is NEVER any energy
flowing.

Every half cycle in every EM traveling wave, the instantaneous
power is zero. Would you therefore argue that traveling waves
cannot transfer any energy? Please get real.

Given two parallel water pipes carrying 100 gallons/minute
in opposite directions. I can see you arguing that there
is no NET flow of water. But I cannot see you arguing that
there is no flow of water at all when the pressure of just
one stream can knock you off your feet.

Well that does leave you with a bit of a conundrum since on
an open ended line, zero energy is flowing at every quarter
wavelength point back from the load.

The conundrum is all yours. Every half cycle, every EM
traveling wave is at a zero instantaneous power point.
If EM traveling waves can transfer energy while the
instantaneous power is zero every half cycle, superposing
two of them doesn't present a conundrum at all.

At such a point a real instantaneous wattmeter would always
indicate zero.

A real instantaneous wattmeter would always indicate zero
at the zero crossing of every EM traveling wave in the
universe so exactly how does the light from Alpha Centauri
ever make it to Earth when the instantaneous power is zero
every half cycle? Please get real.
--
73, Cecil http://www.w5dxp.com

Analyzing Stub Matching with Reflection Coefficients
 

Keith Dysart wrote:
For example, in all your examples you now provide a circulator
because you think this is the only way to control reflections,
when in fact, all that is necessary is a source impedance that is
equivalent to the line impedance and there will be no reflection.

Your above statement has been proved wrong in any number
of bench experiments.

In other cases you claim that problems are insolvable because
insufficient information is provided about the generator. In fact,
all you need to do is use the source impedance to compute
the reflection coefficient and the problem is solved.

Again, proved wrong by any number of bench experiments.

You claim that superposition does not work in a generator.

Not that it doesn't work - just that it is impossible
for a reflected wave to compete with an active dynamic
source. The source essentially ignores the reflected
wave like a fire hose ignores you trying to spit up
the hose against the flow.

You will find that the alternatives work better, ...

Sorry Keith, I stopped listening to you when you asserted
that I is voltage.
--
73, Cecil http://www.w5dxp.com

Analyzing Stub Matching with Reflection Coefficients
 

On Apr 20, 9:13 am, Cecil Moore wrote:
Keith Dysart wrote:
But a key realization is that the behaviour on the line
can not depend on arcane details about the construction of the
generator.

Agreed, but the behavior on the line also doesn't depend
upon where the forward and reverse traveling wave came from.
All that is important is their existence. The reverse
traveling wave might come from a separate source and the
line doesn't know the difference.

All true, and as long as you think of voltage and current waves
you won't get into trouble.

So when such statements are made, it is instructive
to explore the situation with a different generator. If the outcome
is different, then there is something wrong with the theory.

No, if the outcome is different, something different is
happening while abiding by the wave reflection model rules.
Why are you surprised that changes occur when something is
changed?

The key point is that the line conditions did not change, so the
same reflections must be occuring and yet your explanation
claims that sometimes nothing is reflected and sometimes
all is reflected.

Note
that the standard explanations only require that the impedance
of the source be known.

If the "standard explanations" were correct, this would
have been put to bed a long time ago.

And it was. But there are always a few stragglers.

But how does it know, since the output (source) impedances are
the same for both cases?

Conclusion: The output source impedance is NOT the impedance
encountered by the reflected wave. That's essentially what
Walter Maxwell's paper says.

Did you read the same paper I read? I recall that the claim was a
conjugate match of the effective impedances AFTER tuning. The
systems under discussion here have not been tuned for maximum
power transfer.

I think you have made this mistakte before. In my expression P=VI,
V and I are simultaneous instantaneous values and P is the
instantaneous power. If you want average you need to integrate
and divide.

No, if you want to average sinusoidals , use RMS values, which
is the result of said integrating and dividing. Somebody else
already did all the work.

This is true, but reflection is an instantaneous behaviour.
Simplifying
the analysis to RMS or average values, while often effective, bears
many risks in misleading the understanding, as demonstrated here.

Your expression applies only to sine waves and V and I are peak
voltages.

I is a peak voltage??????? You are more confused than
I ever realized. :-)

Oh darn. A typo. I know it will be quoted over and over in subsequent
posts. So be it.

Well, actually two typos. It should read "V and I are RMS voltages
and currents".

Interestingly, the expression P=V*I*cos(theta) for sine
waves is always derived by starting with Pinst=Vinst*Iinst,

Interestingly, you forgot to say you were talking about
instantaneous power until now.

My apologies. I did not mean to confuse you. Since reflection is
an instantaneous phenomenon, I just tend to think of it that way.

True. But there IS energy flowing at every point that is not a voltage
minimum or maximum. At these points there is NEVER any energy
flowing.

Every half cycle in every EM traveling wave, the instantaneous
power is zero. Would you therefore argue that traveling waves
cannot transfer any energy? Please get real.

Of course not. But when the instaneous power is 0 for all instants
then no energy can be flowing.

Given two parallel water pipes carrying 100 gallons/minute
in opposite directions. I can see you arguing that there
is no NET flow of water. But I cannot see you arguing that
there is no flow of water at all when the pressure of just
one stream can knock you off your feet.

Given one pipe of water, I also would not argue there are 10**9
gallons flowing per minute in one direction and 10**9 gallons
flowing per minute in the other, but the net is 0 so all is well.

That is analagous to the claim being made for forward and
reverse energy carrying travelling waves. Are you arguing
that for the water?

Well that does leave you with a bit of a conundrum since on
an open ended line, zero energy is flowing at every quarter
wavelength point back from the load.

The conundrum is all yours. Every half cycle, every EM
traveling wave is at a zero instantaneous power point.
If EM traveling waves can transfer energy while the
instantaneous power is zero every half cycle, superposing
two of them doesn't present a conundrum at all.

Except at those points where for every instant the instantaneous
energy transfer is zero.

At such a point a real instantaneous wattmeter would always
indicate zero.

A real instantaneous wattmeter would always indicate zero
at the zero crossing of every EM traveling wave in the
universe so exactly how does the light from Alpha Centauri
ever make it to Earth when the instantaneous power is zero
every half cycle? Please get real.

There is quite a difference between the instanteous power being
occasionally zero and being zero for all instances. Real enough?

....Keith

Analyzing Stub Matching with Reflection Coefficients
 

On Apr 20, 9:23 am, Cecil Moore wrote:
Keith Dysart wrote:
For example, in all your examples you now provide a circulator
because you think this is the only way to control reflections,
when in fact, all that is necessary is a source impedance that is
equivalent to the line impedance and there will be no reflection.

Your above statement has been proved wrong in any number
of bench experiments.

Actually, most bench experiments demonstrate the opposite.
Were you to take a moment and look at the schematic for any
typical signal generator, you would find the resistor that matches
the generator to the line and prevents reflection of signals
incident upon the generator.

In other cases you claim that problems are insolvable because
insufficient information is provided about the generator. In fact,
all you need to do is use the source impedance to compute
the reflection coefficient and the problem is solved.

Again, proved wrong by any number of bench experiments.

It would be educational if you could describe one of these
experiments.

Remember, you are looking for a re-reflection of the reverse signal
at a generator whose source (output) impedance matches the line
characteristic impedance.

You claim that superposition does not work in a generator.

Not that it doesn't work - just that it is impossible
for a reflected wave to compete with an active dynamic
source. The source essentially ignores the reflected
wave like a fire hose ignores you trying to spit up
the hose against the flow.

Either it works, or it doesn't. Superposition in circuit theory
is not dependant on the relative magnitudes of any of the
sources.

You will find that the alternatives work better, ...

Sorry Keith, I stopped listening to you when you asserted
that I is voltage.

Darn. I knew that typo would show up again. On the other
hand, I can take some pleasure in accurate predictions.

....Keith

Analyzing Stub Matching with Reflection Coefficients
 

Cecil Moore wrote:
Gene Fuller wrote:
Where are the equations that describe this "delta-t" stuff that you
keep bringing up?

I made an error in my last reply and have canceled that reply.

delta-t is a mathematical term, Gene, related in the limit
to the differential dt. If you have to ask, I'm sure you
wouldn't understand the explanation.

Given the following experiment with two signal generators
equipped with circulators and load resistors - the generators
are phased-locked to ensure coherency:

[random s-parameter babble snipped]

How
long does it take to achieve b1 = s11(a1) + s12(a2) = 0?
I estimate that time to be delta-t which becomes dt
in the differential equation limit.

The principle of superposition allows us to observe that
s11(a1) and a12(a2) actually existed before they were
canceled.

Cecil,

That's typical; you don't have a clue about what you have dragged
yourself into.

Let's see. Delta-t is, uhhhh, delta-t. And of course we can replace
delta-t by the differential form, dt, if we choose. You haven't offered
the slightest justification for this bizarre formulation. Where are the
equations that include delta-t or dt? Sure, Maxwell's equations include
time derivatives, but somehow that does not seem to offer much help for
your delta-t dilemma. I always though that part of the utility of
s-parameters is that they do not have any time dependence in steady
state conditions. Is there some equation for ds11/dt that I missed?

I would sure like to see your definition of "the principle of
superposition" if it somehow says that something existed before it was
canceled. I cannot find that definition in any of my sources.

8-)

73,
Gene
W4SZ

Analyzing Stub Matching with Reflection Coefficients
 

On Apr 19, 3:24 pm, Cecil Moore wrote:

Interaction is certainly required for them to cancel forever.

So let it be written, so let it be done. :-)

Otherwise, we have all these energyless phantom ghost waves
existing forever.

Apparently you intend to concern yourself with waves which never
existed, forever.

73, AC6XG

Analyzing Stub Matching with Reflection Coefficients
 

On Apr 19, 7:47 pm, Richard Clark wrote:
On Thu, 19 Apr 2007 17:51:10 -0700, Jim Kelley
wrote:

So I gotta ask: what do waves do instead of superposing when there
isn't a load somewhere? Whistle and look the other way? :-)

Hi Jim,

What do they DO?

I was hoping to persuade you to tell us, Richard. In your post, you
only told us what they don't do.

73, Jim AC6XG

Analyzing Stub Matching with Reflection Coefficients
 

Keith Dysart wrote:
All true, and as long as you think of voltage and current waves
you won't get into trouble.

I don't recall Maxwell's equations relying on "voltage and
current waves".

The key point is that the line conditions did not change, so the
same reflections must be occuring and yet your explanation
claims that sometimes nothing is reflected and sometimes
all is reflected.

If you put two signal generators equipped with circulator
loads at each end of a transmission line, there are absolutely
no reflections anywhere. Yet there is a forward wave and a
reverse wave. We can cause a reverse wave when "sometimes
nothing is reflected and sometimes all is reflected". The
transmission line will not know the difference.

Did you read the same paper I read? I recall that the claim was a
conjugate match of the effective impedances AFTER tuning. The
systems under discussion here have not been tuned for maximum
power transfer.

The existence of a conjugate match is irrelevant to our
discussion. All that is relevant to our discussion is
that the reflected waves does not see the generator
source impedance.

Oh darn. A typo. I know it will be quoted over and over in subsequent
posts. So be it.

Keith, arrogant omniscient beings, as you present yourself
to be :-), do not make typos.

Of course not. But when the instaneous power is 0 for all instants
then no energy can be flowing.

The instantaneous power is zero every 1/2WL in an EM wave.
Therefore, according to you, EM waves cannot transfer energy
or power. Good luck on that one.

There is quite a difference between the instanteous power being
occasionally zero and being zero for all instances. Real enough?

If the instantaneous power is zero for all space and time,
an EM wave cannot exist.
--
73, Cecil, w5dxp.com

Analyzing Stub Matching with Reflection Coefficients
 

Keith Dysart wrote:
It would be educational if you could describe one of these
experiments.

I already did - Bruene's early 1990's QST article.

Remember, you are looking for a re-reflection of the reverse signal
at a generator whose source (output) impedance matches the line
characteristic impedance.

It happened with your pet generator from which you quickly
tried to divert attention. Zero power dissipation inside
a "matched" source is hard to sweep under the rug, huh?

Either it works, or it doesn't.

Superposition works in some situations and doesn't work
in others. For instance, it doesn't work with power.
--
73, Cecil, w5dxp.com

Analyzing Stub Matching with Reflection Coefficients
 

On 20 Apr 2007 09:34:11 -0700, Jim Kelley wrote:

On Apr 19, 7:47 pm, Richard Clark wrote:
On Thu, 19 Apr 2007 17:51:10 -0700, Jim Kelley
wrote:

So I gotta ask: what do waves do instead of superposing when there
isn't a load somewhere? Whistle and look the other way? :-)

Hi Jim,

What do they DO?

I was hoping to persuade you to tell us, Richard. In your post, you
only told us what they don't do.

Hi Jim,

They do nothing. It is still an odd question - unless it was posed
for the benefit of lurkers who are in doubt.

73's
Richard Clark, KB7QHC

Analyzing Stub Matching with Reflection Coefficients
 

Richard Clark wrote:

On 20 Apr 2007 09:34:11 -0700, Jim Kelley wrote:


On Apr 19, 7:47 pm, Richard Clark wrote:

On Thu, 19 Apr 2007 17:51:10 -0700, Jim Kelley
wrote:


So I gotta ask: what do waves do instead of superposing when there
isn't a load somewhere? Whistle and look the other way? :-)

Hi Jim,

What do they DO?

I was hoping to persuade you to tell us, Richard. In your post, you
only told us what they don't do.


Hi Jim,

They do nothing. It is still an odd question - unless it was posed
for the benefit of lurkers who are in doubt.

Hi Richard,

Actually, it was posted because of doubt about your claim "Remove the
load, and you remove interference." Please describe this phenomenon
in more detail. The implications are huge.

Thanks,

Jim AC6XG

Analyzing Stub Matching with Reflection Coefficients
 

On Fri, 20 Apr 2007 11:23:24 -0700, Jim Kelley
wrote:

Actually, it was posted because of doubt about your claim "Remove the
load, and you remove interference." Please describe this phenomenon
in more detail. The implications are huge.

Hi Jim,

Implications aside, it would help us all if you simply describe your
doubt instead of having me fish for your problem.

73's
Richard Clark, KB7QHC

Analyzing Stub Matching with Reflection Coefficients
 

Gene Fuller wrote:
Where are the equations that include delta-t or dt?

Unfortunately, for that type of detail, I need to reference
my technical library which is 125 miles away at my new QTH.
Please stand by.
--
73, Cecil http://www.w5dxp.com

Analyzing Stub Matching with Reflection Coefficients
 

Jim Kelley wrote:
So let it be written, so let it be done. :-)

That's much more in accordance with your omniscience, Jim.

Apparently you intend to concern yourself with waves which never
existed, forever.

The keepers of the s-parameter analysis will be interested
to know that you can prove that s11(a1) and s12(a2) never
existed. Have you contacted them with your insight?
--
73, Cecil http://www.w5dxp.com

Analyzing Stub Matching with Reflection Coefficients
 

Richard Clark wrote:
On Fri, 20 Apr 2007 11:23:24 -0700, Jim Kelley
wrote:


Actually, it was posted because of doubt about your claim "Remove the
load, and you remove interference." Please describe this phenomenon
in more detail. The implications are huge.


Hi Jim,

Implications aside, it would help us all if you simply describe your
doubt instead of having me fish for your problem.

Hello again Richard,

Seems we're having some difficulty communicating so I'll do you the
favor that you rarely extend to anyone, and speak as plainly as
possible. The subject matter is interference; a result of the
superposition of waves. Your assertion regarding the phenomenon is:
"No load, and any issue of canceling fields is strictly limited to
what goes on between the ears."

My question, plainly put is: What in the hell are you talking about?

Thanks and regards,

Jim, AC6XG

Analyzing Stub Matching with Reflection Coefficients
 

Cecil Moore wrote:

The keepers of the s-parameter analysis will be interested
to know that you can prove that s11(a1) and s12(a2) never
existed. Have you contacted them with your insight?

You should notify them immediately of this outrage! (Then afterwards
you can verify that s-parameters must indeed always have non-zero values.)

:-)

ac6xg

Analyzing Stub Matching with Reflection Coefficients
 

On Fri, 20 Apr 2007 12:23:26 -0700, Jim Kelley
wrote:

Your assertion regarding the phenomenon is:
"No load, and any issue of canceling fields is strictly limited to
what goes on between the ears."

My question, plainly put is: What in the hell are you talking about?

Hi Jim,

This quote of mine is simply an example of poetic license, it is to
suggest that without a load, interference is a concept trapped in the
mind and unrealized = there is no interference. You asked several
times about what do the waves DO, and certainly this was one of many
expressions I've offered that responded to that. I didn't see why
repetition was necessary, or that I had to construct yet another
elaboration, unless you were fishing for stylistic variation. I would
be happy to go there! ;-)

It helps to know what your doubt was about, as we would have gone
around the track several times to home in on one sentence.

73's
Richard Clark, KB7QHC

Analyzing Stub Matching with Reflection Coefficients
 

Richard Clark wrote:

This quote of mine is simply an example of poetic license, it is to
suggest that without a load, interference is a concept trapped in the
mind and unrealized = there is no interference. You asked several
times about what do the waves DO, and certainly this was one of many
expressions I've offered that responded to that. I didn't see why
repetition was necessary, or that I had to construct yet another
elaboration, unless you were fishing for stylistic variation. I would
be happy to go there! ;-)

Please, no. Repetition in lieu of elaboration would only deepen the
mystery of why someone would hold such an untenable viewpoint. ;-)

73,
Jim AC6XG

Analyzing Stub Matching with Reflection Coefficients
 

Jim Kelley wrote:
Cecil Moore wrote:
You should notify them immediately of this outrage! (Then afterwards you
can verify that s-parameters must indeed always have non-zero values.)

You are implying that they must have a zero value.
If that is true, an s-parameter analysis is an
exercise in futility.

I'll make it easy for you.

s11(a1) = 5 at zero degrees

s12(a2) = 5 at 180 degrees

b1 = s11(a1) + s12(a2) = 0

Is s11(a1) = 0? _______

Is s12(a2) = 0? _______

Is b1 = 0? ______
--
73, Cecil http://www.w5dxp.com

Analyzing Stub Matching with Reflection Coefficients
 

On Apr 20, 1:27 pm, Jim Kelley wrote:
....
Please, no. Repetition in lieu of elaboration would only deepen the
mystery of why someone would hold such an untenable viewpoint. ;-)

73,
Jim AC6XG

http://www.gocomics.com/nonsequitur/2007/04/16/

Cheers,
Tom

Analyzing Stub Matching with Reflection Coefficients
 

On Fri, 20 Apr 2007 13:27:33 -0700, Jim Kelley
wrote:

Please, no. Repetition in lieu of elaboration would only deepen the
mystery of why someone would hold such an untenable viewpoint. ;-)


Hi Jim,

And thus we return to the unanswered question:

Implications aside, it would help us all if you simply describe your
doubt instead of having me fish for your problem.

73's
Richard Clark, KB7QHC

Analyzing Stub Matching with Reflection Coefficients
 

Cecil Moore wrote:

You are implying that they must have a zero value.
If that is true, an s-parameter analysis is an
exercise in futility.

Ok Cecil. I give up. You're right. The waves from the canceled
electromagnetic fields are there and they are not there.

Trying to have a rational discussion with you - now that's an exercise
in futility.

73, ac6xg

Analyzing Stub Matching with Reflection Coefficients
 

Jim Kelley wrote:
Ok Cecil. I give up. You're right. The waves from the canceled
electromagnetic fields are there and they are not there.

You seem not to be able to separate the past from the
present, Jim. The electromagnetic fields were there
and now they are not there any more. Here is a before
and after example for you.

Given the following experiment with two signal generators
equipped with circulators and load resistors - the generators
are phased-locked to ensure coherency. The two feedlines
are of equal electrical lengths.

SGCL1 is turned on. SGCL2 is turned off.

100W | 25W
50 ohm---50 ohm line---+---291.4 ohm line---291.4 ohm
SGCL1 --Prev1 | SGCL2

What is Pref1 before SGCL2 is turned on? What is Pref1
after SGCL2 is turned on? Did Pref1 change after SGCL2
is turned on?

Since Pref1 *NEVER* encounters the impedance discontinuity
how can it possibly be affected by SGCL2 being turned on?
--
73, Cecil http://www.w5dxp.com

Analyzing Stub Matching with Reflection Coefficients
 

Gene Fuller wrote:
Where are the equations that describe this "delta-t" stuff that you keep
bringing up?

Actually, Gene, the example I just posted for Jim will answer
your question.

SGCL1 is turned on. SGCL2 is turned off.

100W | 25W
50 ohm---50 ohm line---+---291.4 ohm line---291.4 ohm
SGCL1 --Prev1 | SGCL2

When SGCL2 is turned on let t=0 be the time when the
SGCL2 source wave reaches the impedance discontinuity
at point '+'. How long does it take for that source
wave to affect Prev1? Whatever length of time that is,
that's the length of delta-t.
--
73, Cecil http://www.w5dxp.com

Analyzing Stub Matching with Reflection Coefficients
 

Cecil Moore wrote:
Jim Kelley wrote:

Ok Cecil. I give up. You're right. The waves from the canceled
electromagnetic fields are there and they are not there.


You seem not to be able to separate the past from the
present, Jim.

The electromagnetic fields were there
and now they are not there any more.

There is no reference to time in an s-parameter analysis. That is
because it assumes steady state. The purpose of doing analysis in the
steady state is because past and present are irrelevant. S-parameter
analysis doesn't support your claim. There is no support for your claim.

ac6xg

Analyzing Stub Matching with Reflection Coefficients
 

Cecil Moore wrote:
Gene Fuller wrote:
Where are the equations that describe this "delta-t" stuff that you
keep bringing up?

Actually, Gene, the example I just posted for Jim will answer
your question.

SGCL1 is turned on. SGCL2 is turned off.

100W | 25W
50 ohm---50 ohm line---+---291.4 ohm line---291.4 ohm
SGCL1 --Prev1 | SGCL2

When SGCL2 is turned on let t=0 be the time when the
SGCL2 source wave reaches the impedance discontinuity
at point '+'. How long does it take for that source
wave to affect Prev1? Whatever length of time that is,
that's the length of delta-t.


Cecil,

BZZZZT! Wrong answer.

We are talking steady state, remember? You need to dig a bit deeper. I
won't hold my breath waiting. I will give you extra credit for a vivid
imagination, however.

73,
Gene
W4SZ

Analyzing Stub Matching with Reflection Coefficients
 

Jim Kelley wrote:
There is no support for your claim.

There is plenty of support for my claim, Jim, but you
deleted it. I will simply repost it over and over until
you respond.

Given the following experiment with two signal generators
equipped with circulators and load resistors - the generators
are phased-locked to ensure coherency. The two feedlines
are of equal electrical lengths.

SGCL1 is turned on. SGCL2 is turned off.

100W | 25W
50 ohm---50 ohm line---+---291.4 ohm line---291.4 ohm
SGCL1 --Prev1 | SGCL2

What is Pref1 before SGCL2 is turned on? What is Pref1
after SGCL2 is turned on? Did Pref1 change after SGCL2
is turned on?

Since Pref1 *NEVER* encounters the impedance discontinuity
how can it possibly be affected by SGCL2 being turned on?
This is a perfect example of wave interaction.
--
73, Cecil http://www.w5dxp.com

Analyzing Stub Matching with Reflection Coefficients
 

Gene Fuller wrote:
We are talking steady state, remember? You need to dig a bit deeper. I
won't hold my breath waiting. I will give you extra credit for a vivid
imagination, however.

This is steady-state after the wave interaction. What
you guys don't seem to realize is that s11(a1) and
s12(a2) are continually changing, continually
interacting, and a1 & a2 are rotating phasors
changing with time.
--
73, Cecil http://www.w5dxp.com

Analyzing Stub Matching with Reflection Coefficients
 

Cecil Moore wrote:
Gene Fuller wrote:
We are talking steady state, remember? You need to dig a bit deeper. I
won't hold my breath waiting. I will give you extra credit for a vivid
imagination, however.

This is steady-state after the wave interaction. What
you guys don't seem to realize is that s11(a1) and
s12(a2) are continually changing, continually
interacting, and a1 & a2 are rotating phasors
changing with time.

Cecil,

Utter nonsense. Any setup that includes t0 or t=0 is not steady state.


73,
Gene
W4SZ

Analyzing Stub Matching with Reflection Coefficients
 

"Gene Fuller" wrote
Gene Fuller wrote:
We are talking steady state, remember? You need to dig a bit deeper. I
won't hold my breath waiting. I will give you extra credit for a vivid
imagination, however.

This is steady-state after the wave interaction. What
you guys don't seem to realize is that s11(a1) and
s12(a2) are continually changing, continually
interacting, and a1 & a2 are rotating phasors
changing with time.

Cecil,

Utter nonsense. Any setup that includes t0 or t=0 is not steady state.


73,
Gene
W4SZ

Gene: Perhaps Cecil should be using one of Art's equations that
include the cessation of time? (snork!)

Mike W5CHR

Analyzing Stub Matching with Reflection Coefficients
 

On Apr 20, 12:38 pm, Cecil Moore wrote:
Keith Dysart wrote:
All true, and as long as you think of voltage and current waves
you won't get into trouble.

I don't recall Maxwell's equations relying on "voltage and
current waves".

You have that right. Just some simple differential equations.

The key point is that the line conditions did not change, so the
same reflections must be occuring and yet your explanation
claims that sometimes nothing is reflected and sometimes
all is reflected.

If you put two signal generators equipped with circulator
loads at each end of a transmission line, there are absolutely
no reflections anywhere. Yet there is a forward wave and a
reverse wave. We can cause a reverse wave when "sometimes
nothing is reflected and sometimes all is reflected". The
transmission line will not know the difference.

Rather a non-sequitor since we were discussing what was happening
at the generator end, but non-the-less true and demonstrates again
one of the greater weaknesses in your learnings. You really do need
to realize that there is no need for a circulator. Once you are beyond
this, many things will fall into place.

Did you read the same paper I read? I recall that the claim was a
conjugate match of the effective impedances AFTER tuning. The
systems under discussion here have not been tuned for maximum
power transfer.

The existence of a conjugate match is irrelevant to our
discussion. All that is relevant to our discussion is
that the reflected waves does not see the generator
source impedance.

There you go. Still stuck. You really should crack the books in search
of a reference to support your contention. You won't find one.

And the relevence of the conjugate match is that the conjugate
is the generator source impedance and it is the impedance that
the wave incident upon the generator sees.

Oh darn. A typo. I know it will be quoted over and over in subsequent
posts. So be it.

Keith, arrogant omniscient beings, as you present yourself
to be :-), do not make typos.

Of course not. But when the instaneous power is 0 for all instants
then no energy can be flowing.

The instantaneous power is zero every 1/2WL in an EM wave.
Therefore, according to you, EM waves cannot transfer energy
or power. Good luck on that one.

I have certainly never said that. If you could point me to the words
that misled you into thinking that, I will attempt to clarify your
misunderstanding.

There is quite a difference between the instanteous power being
occasionally zero and being zero for all instances. Real enough?

If the instantaneous power is zero for all space and time,
an EM wave cannot exist.

My point exactly.

....Keith

Analyzing Stub Matching with Reflection Coefficients
 

On Apr 20, 12:46 pm, Cecil Moore wrote:
Keith Dysart wrote:
It would be educational if you could describe one of these
experiments.

I already did - Bruene's early 1990's QST article.

Sorry. Not a good enough description for any kind of analysis.

Remember, you are looking for a re-reflection of the reverse signal
at a generator whose source (output) impedance matches the line
characteristic impedance.

It happened with your pet generator from which you quickly
tried to divert attention. Zero power dissipation inside
a "matched" source is hard to sweep under the rug, huh?

Nothing to sweep under the rug, I am afraid. It is key that the
dissipation depends on the design of the generator. Some
times those 'reverse watts' cause the dissipation to drop
to 0, sometimes they cause it to increase by a factor of 4,
sometimes they cause it to increase by the numerical value
of the 'reverse watts'. Pretty much hard to argue that those
'reverse watts' are real when their heating effect is so
variable.

Either it works, or it doesn't.

Superposition works in some situations and doesn't work
in others. For instance, it doesn't work with power.

I'd suggest you think of power as a quantity not a situation.
Superposition works for linear, time invariant circuits with
multiple sources. Check any text book. The generators and
lines under discussion meet these requirements.

I realize the results of superposition are inconvenient for
your explanations, but it would be better to examine your
explanations than to discard superposition. You will then
be free to use superposition to solve problems you
currently consider unsolvable.

....Keith