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