Owen Duffy wrote:
It is a leap to move from "can be thought of as power" or "has the
dimension of power" to your statement (which you attribute to HP AN95-1)
"The beauty of an S-Parameter analysis is that if one squares the
normalized voltages, one gets power." Did AN95-1 state clearly that which
you suggest?

The answer is "yes, they did." But, if you insist, I am willing to
change what HP said to "one gets the dimensions of power, i.e.
joules/second." As an engineer, I am content with getting close
enough but I am always agreeable to accommodating the purists.

Nowhere in Chapter 1 of AN154 do they perform alegebraic operations on
power, the chapter is full of expressions, but they do not use |Sxx|^2.

How about Chapter 2? :-)

I will have to check out that Ap Note. In the meanwhile, maybe
you should take a look at Ap Note 95-1 from which I will quote
one example (there are others) from page 17:

|s11|^2 = Power reflected from the network input divided by Power
incident on the network input. Please adjust your thinking
to agree with HP's.

So not you are superposing power to "yield" a resultant power.

My native language is American English but I cannot parse that
statement. Care to try again, maybe in the Queen's English? :-)

Power density can be added using the scalar intensity, irradiance,
or Poynting vector equations, but POWER CANNOT BE SUPERPOSED!!!
I don't know how many times I have to repeat that statement.
--
73, Cecil http://www.w5dxp.com

Owen Duffy wrote:
So now you are superposing power to "yield" a resultant power.

I see you corrected your English. :-) The answer is NO, powers
cannot be superposed. There is a specialized equation for adding
powers and it is *NOT* a superposition equation. Born and Wolf
call it the "total intensity" equation with an included
"interference" term. Their words, not mine.

The equation also appears in Dr. Best's QEX article of Nov/Dec
2001 and in "Optics", by Hecht.
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:
Gene Fuller wrote:
quoting Born & Wolf:
"However, when the definition has been applied cautiously, in
particular for averages of small but finite regions of space or time,
no contradictions with experiments have been found. We shall therefore
accept the above definition in terms of the Poynting vector of the
density of the energy flow."

There's the meat of the quote as far as transmission lines
are concerned. Given that transmission lines are "small but
finite regions of space or time", and since there are only
two possible directions in a transmission line, Born and
Wolf seem to give us permission to do exactly what you
are complaining about. Your concerns about light waves
in three dimensional free space just don't exist for the
primarily single dimensional "space" in a transmission line.
Ideally, the power density exists only between the inner and
outer conductors of the coax.

It does not make any sense to simply add and subtract Poynting vectors
in elementary fashion and expect to get correct results.

Born & Wolf's own words in the quote above provided by you
contradict that assertion.


Cecil,

You conveniently chopped out the part of the B&W quote that matters. You
continue to claim that energy associated with each of the myriad of wave
components that exist at the point of interest must be reconciled. The
correct application of the Poynting theorem, as noted in the full B&W
quote, says that your requirement is not correct. Only the net energy
flow into that small integration volume has any physical reality.

Unless there is a source or sink at the point of interest, the net
energy flow will be exactly zero. Further analysis is futile.
Conservation of energy, specifically the Poynting theorem, does not
support you or anyone else who tries to atomize the waves in an attempt
to balance energy contribution from individual wave components. You are
on your own.

By the way, a very similar statement about the application of Poynting
vectors appears in Classical Electrodynamics by Jackson. This is not
some strange interpretation by a single author.

73,
Gene
W4SZ

Cecil Moore wrote:
Gene Fuller wrote:
Why don't you simply stop being such a nitwit. I understand perfectly
what the Java applet is and is not. S-parameters are not a new branch
of science. No one is confused except you.

Before I explained it to you, you obviously had no
clue what that java script represented since you
said it was impossible. Not only is it possible,
it happens every time someone adjusts an antenna
tuner for a match.

Cecil,

By the way, the "nitwit" comment was in reference to dragging global
warming into the discussion. Just a slight bit of a diversion.

8-)

73,
Gene
W4SZ

Gene Fuller wrote:
You conveniently chopped out the part of the B&W quote that matters.

No, I quoted the part of the B&W quote that matters.

Further analysis is futile.

Gene, are you a Borg?
--
73, Cecil http://www.w5dxp.com

Gene Fuller wrote:
By the way, the "nitwit" comment was in reference to dragging global
warming into the discussion. Just a slight bit of a diversion.

Speaking of which, the global warming gurus are predicting
global chaos. The fact is that ~130K years ago, the Earth
began 10K years of global warming followed by an ice age.
The temperature 120K years ago averaged two degrees hotter
than it is today. 18K years ago, we began another 10K year
period of global warming that brought us out of the last
ice age and peaked 8K years ago two degrees hotter than it
is today. For the past 8K years, the Earth has been ever
so slowly slipping into another ice age. Al Gore knows
just about as much about global warming as you do about
destructive interference. Are you a Democrat? :-)
--
73, Cecil http://www.w5dxp.com

On Apr 15, 12:56 pm, Cecil Moore wrote:
Jim, I challenge you to find anything wrong with this S-
Parameter analysis.
It follows exactly Born and Wolf's
intensity equations for constructive interference when
the phase angle between a1 and a2 is 180 degrees and
their magnitudes are equal.

Profound. Wouldn't it be strange if other texts had similar ideas
too?...

Let us know when HP gets around to ammending its S-Parameter treatise
to include the 4th Mechanism of Reflection.

ac6xg

Jim Kelley wrote:
Let us know when HP gets around to ammending its S-Parameter treatise
to include the 4th Mechanism of Reflection.

Please wade through the S-Parameter analysis with me,
see for yourself, and suggest an alternative. The
Florida State web page says the energy involved in
wave cancellation is redistributed "somehow". Wave
cancellation is obviously not a simple reflection
from an impedance discontinuity because it does not
obey the reflection rules.
--
73, Cecil http://www.w5dxp.com

On Apr 16, 5:34 am, Cecil Moore wrote:
Jim Kelley wrote:
Let us know when HP gets around to ammending its S-Parameter treatise
to include the 4th Mechanism of Reflection.

Please wade through the S-Parameter analysis with me,
see for yourself, and suggest an alternative. The
Florida State web page says the energy involved in
wave cancellation is redistributed "somehow". Wave
cancellation is obviously not a simple reflection
from an impedance discontinuity because it does not
obey the reflection rules.
--
73, Cecil http://www.w5dxp.com

Hi Cecil,

I really do appreciate your courteous and patient offer. But in fact,
you have already waded us through that so many times it's kinda funny
that you hope it will somehow turn out differently this time. I don't
understand why the S-parameter analysis is controversial - unless
perhaps you're doing something fanciful with it. If not, it's no lo
contendre. The point of contention is only one or two particular
aspects of your energy analysis. By that I mean _your_ energy
analysis, not Eugene Hechts interference equations (and poor choices
of terms), not B&W's Poynting vector discussion, and not the Hewlett-
Packard s-parameter application note. Although you do frequently
quote, paraphrase, and presume to speak on their behalf, those people
do not post your ideas to rec.radio.amateur.antenna.

73, Jim AC6XG

On Apr 15, 7:49 am, Gene Fuller wrote:
....

Cecil,

I pointed out a few days ago that the FSU Java applet you lean on so
heavily these days is a simple tutorial device designed by a grad
student and a programmer. As shown, it is physically impossible, since
there is no mechanism in place to cause the waves to suddenly jump
together and interfere.

It is a useful picture showing how sine waves with differing phases add
together; no more and no less. It is a simple matter of mathematics. It
is not a new discovery in the world of RF or optics.

73,
Gene
W4SZ

I have yet to see Cecil, or anyone else, post an example of how waves
can become perfectly collinear, except at an interface: a
discontinuity in a transmission line, a partially-reflecting surface
in an interferometer, ... -- a physical interface of some sort.

I have yet to see Cecil, or anyone else, post an example of perfectly
collinear waves that perfectly cancel over some small finite volume
which do not also cancel perfectly at all points up to their point of
origin: a physical interface. In other words, lacking that example,
I see NO physical evidence that those waves exist beyond that "point
of origin." Specifically, I have not seen an example of a uniform TEM
line on which it is supposed that two waves cancel perfectly over some
distance, but over some other length on the same line with no
interposed interfaces, the two do not perfectly cancel.

I have yet to see Cecil, or anyone else, post an example wherein the
behaviour of a uniform, linear TEM transmission line is not adequately
explained by the propagation constant of the line, the concept that Vf/
If=-Vr/Ir=Zo, Vtotal=Vf+Vr, and Itotal=If+Ir, and the boundary
conditions at any transitions or interfaces.

Whether or not any claims about power and energy formulas are accurate
or not, I don't know. I'd have to be convinced they're actually
useful before I looked at them more closely. So far, I've not been
convinced of their utility. But then maybe I'm just slow. I could
never see how the current at two ends of a wire (with no other
conductive paths between the ends) could be different unless the wire
in between was storing or giving up charge, either, and I was LAUGHED
AT and told that was just flat-out wrong. The laughing didn't seem to
help; I still don't see it.

When I brought up that applet a few days ago, the same thing jumped
out at me, and gave ME a good laugh. Yes, it shows waves cancelling,
but it never shows how they got there.

Cheers,
Tom

This posting (c) 2007; it may be quoted only in its entirety.