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