Walter Maxwell wrote:
Cecil, the only difference that can obtain between reflection coefficents is in
magnitude and phase. It matters not whether a reflection is established by a
physical discontinuity or wave interference, the result is identical.

I agree the results are identical - It matters within the analysis but it
doesn't matter to the outcome. You and Steve get the same outcome. The
things you are arguing over is what happens inside the model each of you
is using.

Now I see your problem, Cecil, and that is because you still don't understand
why a reflection coefficient of 1.0 IS established when two waves equal in
magnitude but of equal and opposite phase occur at the match point.

Walt, please listen to this again. I understand why a reflection coefficient
of 1.0 is established in your model. I understand why it is impossible for a
reflection coefficient of 1.0 to exist in Dr. Best's model. It is now up to you
to understand why it is impossible for a reflection coefficient of 1.0 to exist
in Dr. Best's model. A reflection coefficient of 1.0 also does not and cannot
exist in an S-parameter analysis of the following example.

Cecil, we don't need to argue the conditions concerning S-parameter analysis,
because I've put my finger on the problem you're having with this entire
discussion, that is you're (and Steve's) unwillingness to understand that wave
interference can establish a reflection coefficient of 1.0 without any physical
means.

It is IMPOSSIBLE to establish a reflection coefficient of 1.0 in an S-parameter
analysis of the following:

100W XMTR---50 ohm line---x---1/2WL 150 ohm line---50 ohm load

The reflection coefficient at point 'x' in Dr. Best analysis is ABSOLUTELY
CONSTANT at 0.5. It NEVER changes from 0.5. It is always (150-50)/(150+50)
equals 0.5. It NEVER becomes 1.0 as it does in your analysis. A reflection
coefficient of 1.0 is ABSOLUTELY IMPOSSIBLE using an S-parameter analysis of
the above configuration.

Using an S-parameter analysis, a reflection coefficient of 1.0 DOES NOT exist
anywhere and CANNOT exist anywhere. Until you accept that fact, you will continue
to be confused.

Let me say it once again: THE "REFLECTION COEFFICIENT" THAT YOU ARE USING HAS
A DIFFERENT DEFINITION THAN THE "REFLECTION COEFFICIENT" THAT DR. BEST IS USING.
IT IS IMPOSSIBLE FOR DR. BEST'S REFLECTION EVER TO EQUAL 1.0. Dr. Best's rho is
NOT equal to and is NEVER equal to SQRT(Pr/Pf). Why is that so hard to understand?
--
73, Cecil http://www.qsl.net/w5dxp



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On Thu, 10 Jun 2004 13:16:34 -0500, Cecil Moore wrote:

Walter Maxwell wrote:
Cecil, the only difference that can obtain between reflection coefficents is in
magnitude and phase. It matters not whether a reflection is established by a
physical discontinuity or wave interference, the result is identical.

I agree the results are identical - It matters within the analysis but it
doesn't matter to the outcome. You and Steve get the same outcome. The
things you are arguing over is what happens inside the model each of you
is using.

Cecil, you keep saying Steve and I get the same outcome. Where do you see that
result ? The fact that Steve's outcome is incorrect in general, and nowhere
agrees with mine, how can you say we get the same outcome?

Now I see your problem, Cecil, and that is because you still don't understand
why a reflection coefficient of 1.0 IS established when two waves equal in
magnitude but of equal and opposite phase occur at the match point.

Walt, please listen to this again. I understand why a reflection coefficient
of 1.0 is established in your model. I understand why it is impossible for a
reflection coefficient of 1.0 to exist in Dr. Best's model. It is now up to you
to understand why it is impossible for a reflection coefficient of 1.0 to exist
in Dr. Best's model. A reflection coefficient of 1.0 also does not and cannot
exist in an S-parameter analysis of the following example.

Why do you keep insisting on an S-parameter analysis? What good are you
accomplishing with it ? And speaking of Steve's model--he shows it in his Fig 5
as a simple T-network as used in most antenna tuners. The effect at the input
of the network is no different than in a stub model or a 1/4 wl transformer
model. You can't rely on 'different models' to explain away the problem. When
properly adjusted to match the output to the input in his T-network the
reflected power reaching the input is totally re-reflected. This results only
from a reflection coefficient of 1.0. Saying that it is impossible for a 1.0 to
exist in Steve's model is simply not true. Steve simply doesn't understand the
wave mechanics involved here.

Cecil, we don't need to argue the conditions concerning S-parameter analysis,
because I've put my finger on the problem you're having with this entire
discussion, that is you're (and Steve's) unwillingness to understand that wave
interference can establish a reflection coefficient of 1.0 without any physical
means.

It is IMPOSSIBLE to establish a reflection coefficient of 1.0 in an S-parameter
analysis of the following:

100W XMTR---50 ohm line---x---1/2WL 150 ohm line---50 ohm load

It's true that the physical reflection coefficient is 0.5. How then do you
account for ALL the reflected energy being re-reflected to the load? The fact
is that a reflection coefficient of 1.0 is also established there by wave
interference. You really must come to the grips with the fact that a reflection
coefficient of 1.0 can be established by wave interference. You are now the one
who won't budge.

The reflection coefficient at point 'x' in Dr. Best analysis is ABSOLUTELY
CONSTANT at 0.5. It NEVER changes from 0.5. It is always (150-50)/(150+50)
equals 0.5. It NEVER becomes 1.0 as it does in your analysis. A reflection
coefficient of 1.0 is ABSOLUTELY IMPOSSIBLE using an S-parameter analysis of
the above configuration.

Using an S-parameter analysis, a reflection coefficient of 1.0 DOES NOT exist
anywhere and CANNOT exist anywhere. Until you accept that fact, you will continue
to be confused.

Let me say it once again: THE "REFLECTION COEFFICIENT" THAT YOU ARE USING HAS
A DIFFERENT DEFINITION THAN THE "REFLECTION COEFFICIENT" THAT DR. BEST IS USING.
IT IS IMPOSSIBLE FOR DR. BEST'S REFLECTION EVER TO EQUAL 1.0. Dr. Best's rho is
NOT equal to and is NEVER equal to SQRT(Pr/Pf). Why is that so hard to understand?

I haven't seen anything in Steve's paper that shows he's using an S-Parameter,
can you show me where? Not that it would make any difference in the outcome.

In addition, referring to your paragraph immediately above, where did you get
the idea that I said Steve's rho = SQRT(Pr/Pf)? Cecil, that's simply SWR, not
rho.

At this point, Cecil, if you are still unable to accept the concept of
establishing a reflection coefficient of 1.0 through wave interference then
there is no use of continuing this discussion. It will never go forward until
you do. I know there are others on this rraa who agree with you, but there are
many more who understand the concept and agree that it's true.

Walt

Walter Maxwell wrote:
Cecil, you keep saying Steve and I get the same outcome. Where do you see that
result ?

You both get the same measurable forward and reflected powers,
forward and reflected voltages, and forward and reflected currents.

Why do you keep insisting on an S-parameter analysis?

Because that is essentially what Steve used and it works. It has
worked for decades. Please download the HP AN 95-1 and see for yourself.

When
properly adjusted to match the output to the input in his T-network the
reflected power reaching the input is totally re-reflected. This results only
from a reflection coefficient of 1.0.

Only in your model, Walt, not in Steve's. Reflection coefficients of 1.0
are INVALID in Steve's quasi-S-parameter model.

Saying that it is impossible for a 1.0 to
exist in Steve's model is simply not true.

Yes, it is true, for the configurations discussed so far. The ONLY time a
reflection coefficient of 1.0 exists in Steve's model is for a *physical*
short, a *physical* open, or a *physical* pure reactance. In Steve's model,
virtual stuff is invalid.

It's true that the physical reflection coefficient is 0.5. How then do you
account for ALL the reflected energy being re-reflected to the load? The fact
is that a reflection coefficient of 1.0 is also established there by wave
interference. You really must come to the grips with the fact that a reflection
coefficient of 1.0 can be established by wave interference. You are now the one
who won't budge.

You are asking me to budge away from the rules of an S-parameter analysis?

Sorry, Walt, virtual reflection coefficients are INVALID in an S-parameter
analysis like Steve is using. The s11 reflection coefficient that Steve uses
is defined as the "input reflection coefficient looking into port 1 with
the output port terminated by a matched load." Since there is no such thing
as a Z0 = 0 or a Z0 = infinity, there is no such thing as a reflection
coefficient equal to 1.0. The reflection coefficient, s11, that Steve is
using can *NEVER* be zero or one - *NOT EVER*.

I haven't seen anything in Steve's paper that shows he's using an S-Parameter,
can you show me where? Not that it would make any difference in the outcome.

His reflection coefficient is (Z2-Z1)/(Z2+Z1). That is identical to the S-parameter
reflection coefficient, s11. It is a constant and never changes to 1.0, no matter
what happens to the reflected power. Dr. Best simply doesn't use virtual
reflection coefficients. Using virtual reflection coefficients in an S-parameter
analysis is *INVALID*, i.e. they simply do not exist.

In addition, referring to your paragraph immediately above, where did you get
the idea that I said Steve's rho = SQRT(Pr/Pf)? Cecil, that's simply SWR, not
rho.

Let's take the 133.33W forward and 33.33W reflected example. rho equals the square
root of (33.33/133.33) = 0.5. That's not SWR, Walt. SWR cannot be less than unity.
That is indeed the physical voltage reflection coefficient.

At this point, Cecil, if you are still unable to accept the concept of
establishing a reflection coefficient of 1.0 through wave interference then
there is no use of continuing this discussion.

I accept the concept of a reflection coefficient of 1.0 for your model, Walt.
But a reflection coefficient of 1.0 is simply NOT allowed in the quasi-S-parameter
analysis that Steve uses. The S-parameter analysis works and has been used for
decades but an s11 of 1.0 simply never happens (except at a short or an open).
The reflection coefficients in an S-parameter analysis and in Steve's analysis
are ***PHYSICAL***. They are ***NEVER*** virtual. I'm sorry if that upsets you.
I don't know what else to say.
--
73, Cecil http://www.qsl.net/w5dxp



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On Thu, 10 Jun 2004 21:17:58 -0500, Cecil Moore wrote:

Walter Maxwell wrote:

In addition, referring to your paragraph immediately above, where did you get
the idea that I said Steve's rho = SQRT(Pr/Pf)? Cecil, that's simply SWR, not
rho.

Let's take the 133.33W forward and 33.33W reflected example. rho equals the square
root of (33.33/133.33) = 0.5. That's not SWR, Walt. SWR cannot be less than unity.
That is indeed the physical voltage reflection coefficient.

You're right, Cecil, the print is so small on my screen I confused the r and f,
yes, it's rho.

At this point, Cecil, if you are still unable to accept the concept of
establishing a reflection coefficient of 1.0 through wave interference then
there is no use of continuing this discussion.

I accept the concept of a reflection coefficient of 1.0 for your model, Walt.
But a reflection coefficient of 1.0 is simply NOT allowed in the quasi-S-parameter
analysis that Steve uses. The S-parameter analysis works and has been used for
decades but an s11 of 1.0 simply never happens (except at a short or an open).
The reflection coefficients in an S-parameter analysis and in Steve's analysis
are ***PHYSICAL***. They are ***NEVER*** virtual. I'm sorry if that upsets you.
I don't know what else to say.

I'm sorry, Cecil, but you are missing the entire point of the discussion. I'm
not upset, I'm just dismayed that you don't see the light. So as I said above
there is no point in continuing the discussion. Some day you'll come to
understand the basis for the problem, and then I'm sure we'll agree.

C ya, Cecil, and take care!

Walt