Constructive interference in radiowave propagation
 

Cecil Moore wrote:
Gene Fuller wrote:
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.

Good Grief, Gene! You are arguing that because you cannot
view them in the present that they never existed in the
past. Such is nonsense.The left hand side is a historical
plot of the points of the waves before they interfere.
Of course, those points only exist back in history and
no longer exist in the present because everything in the
present is happening at a point. Do you also deny the
existence of the historical yearly temperature plot points
because they don't still exist today? Please get real.
Here's a temperature chart to which you can apply your
"impossible" logic concepts.

http://en.wikipedia.org/wiki/Global_warming

Paraphrasing your idea: "As shown, it is physically
impossible, since there is no mechanism in place to
cause more than one temperature to exist at the
present time."

That java example is an example of implementing the
S-Parameter equation b1 = s11(a1) + s12(a2) which
is CERTAINLY NOT IMPOSSIBLE. By adjusting the magnitudes
and phase angles of a1 and a2, any degree of interference
can be obtained. One wave is s11(a1) and the other wave
is s12(a2). Of course, the interference happens at a point
(or plane) so fast that it is impossible to view in real
time. But by using deductive reasoning and the known
laws of physics, we are able to come up with valid java
scripts like the above. Your confusion is in assuming
all those points have to exist simultaneously in the
present, a really, really ridiculous notion.

They do not and cannot exist simultaneously in the present
just as temperatures on a temperature plot of past years
do not and cannot exist in the present anymore. Those points
on the java script existed back in time and are plotted in
a similar manner to plotting temperatures that no longer
exist in the present.



Cecil,

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.

73,
Gene
W4SZ

Constructive interference in radiowave propagation
 

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.

It simply does not matter.

You sure make a lot of postings about it for it not
to matter to you. :-) It certainly matters to me
and others and we will not stop the discussion
until it is resolved to everyone's satisfaction.
What are you afraid we will uncover if we keep
digging? Your ignorance?

It has been pointed out numerous times that modern physical theory is
correct by design. Ian again pointed out that fact earlier today. If the
wave equations, the field equations, force equations, or whatever are
analyzed correctly the energy balance will automatically work out
correctly as well.

The assertions that reflected waves don't exist or if they
do exist, they contain no energy, are false assertions. Trying
to sweep them under the rug by mealy-mouthing some automatic
energy balance religion is just another copout.
--
73, Cecil http://www.w5dxp.com

Constructive interference in radiowave propagation
 

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.
--
73, Cecil http://www.w5dxp.com

Constructive interference in radiowave propagation
 

On Apr 14, 8:57 pm, Cecil Moore wrote:
Jim Kelley wrote:
So I'm happy to
leave it to you to explain to Cecil how waves cancel but without
anhiliating the energy "in" them.

But that's just the point, Jim. You seem to believe the
pre-existing energy in those waves has been destroyed.
They obviously possessed energy before cancellation and
you say they possess zero energy after cancellation. If
that pre-existing energy is not destroyed, where did it go?
--
73, Cecil http://www.w5dxp.com

As I said, Cecil, your ideas about waves 'possessing energy' need a
little work.

ac6xg

Constructive interference in radiowave propagation
 

Jim Kelley wrote:
As I said, Cecil, your ideas about waves 'possessing energy' need a
little work.

Complete lack of technical content or technical defense
of your assertions is noted - nothing but a bunch of
hand-waving.

One more challenge for you, Jim. If you can prove that
an EM wave can exist without the associated ExB energy, you
will no doubt win a Nobel Prize in Physics.

Here's what Hecht says: "Any electromagnetic wave exists
within some region of space, and it is therefore natural
to consider the *radiant energy per unit volume*, or
*energy density*. We suppose that the electric field itself
can somehow store energy. This is a major logical step
since it imparts to the field the attribute of physical
reality - if the field has energy, it is a thing-in-itself."

Maybe it's past time for you to take that logical step
that Hecht took so long ago?

"To represent the flow of electromagnetic energy associated
with a traveling wave, let 'S' symbolize the transport of
energy per unit time (the power) across a unit area. ...
it has come to be known as the *Poynting vector*."

Hecht labels the energy per unit time in an EM wave as
"power". Hecht's Poynting vector equations contain cosine
terms. Hecht shoots down virtually every one of your
assertions and objections.

I notice you carefully avoided my S-Parameter example.
--
73, Cecil http://www.w5dxp.com

Constructive interference in radiowave propagation
 

On Apr 15, 11:58 am, Cecil Moore wrote:
I notice you carefully avoided my S-Parameter example.

I try to comment only on technical things that you say with which I
disagree, Cecil. Though as it happens, most of the objectionable
comments you make are not techincal.

ac6xg

Constructive interference in radiowave propagation
 

Jim Kelley wrote:
As I said, Cecil, your ideas about waves 'possessing energy' need a
little work.

All it takes to prove you wrong is a
look at a typical S-Parameter equation involving
the superposition of two terms. In the following the
'@' sign is used for the angle sign. a1 and a2 are
normalized voltages. s21 is a transmission coefficient.
s22 is a reflection coefficient.

b2 = s21(a1) + s22(a2)

Given a1 = 10 @ 0 deg, a2 = 10 @ 180 deg,
s21 = 0.707 @ 0 deg, s22 = 0.707 @ 180 deg

s21(a1) = 0.707@0(10@0) = 7.07 @ 0 deg

s22(a2) = 0.707@180(10@180) = 7.07 @ 0 deg

superposing those two values gives:

b2 = 14.14 @ 0 deg

All is well and good. Multiply b2 by SQRT(Z0) to get
total forward voltage.

Now let's look at the powers in accordance with HP's
Ap Note 95-1. For that, we don't need to know the Z0.
The beauty of an S-Parameter analysis is that if one
squares the normalized voltages, one gets power.

|s21(a1)|^2 = 50 watts

|s22(a2)|^2 = 50 watts

|b2|^2 = 200 watts

Even in the S-Parameter analysis, superposing two 50W
waves in phase yields 200 watts. Constructive interference
not only makes it possible but demands it.

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.
--
73, Cecil http://www.w5dxp.com

Constructive interference in radiowave propagation
 

Jim Kelley wrote:
Cecil Moore wrote:
I notice you carefully avoided my S-Parameter example.

I try to comment only on technical things that you say with which I
disagree, Cecil. Though as it happens, most of the objectionable
comments you make are not techincal.

Translation: I agree with you technically but I dislike your
personal style so I am going to keep harassing you with
false quotations and kibitzing. Please see my latest S-Parameter
posting where the S-Parameter equations agree perfectly
with Hecht and Born & Wolf, and disagree with you.
--
73, Cecil http://www.w5dxp.com

Constructive interference in radiowave propagation
 

Cecil Moore wrote in news:0svUh.417$Yo2.402
@newssvr19.news.prodigy.net:

Now let's look at the powers in accordance with HP's
Ap Note 95-1. For that, we don't need to know the Z0.
The beauty of an S-Parameter analysis is that if one
squares the normalized voltages, one gets power.

Cecil,

AN95-1 is a slide show, it is a presentation to accompany a talk, and as
such is incomplete.

Another HP note is AN154 which is derived from a training seminar, but is
more complete in its development. Chapter 1 is relevant to your use of S
parameters.


Let me quote:

Notice that the square of the magnitude of these
new variables has the dimension of power. |a1|2
can then be thought of as the incident power on
port one; |b1|2 as power reflected from port one.
These new waves can be called traveling power
waves rather than traveling voltage waves.
Throughout this seminar, we will simply refer to
these waves as traveling waves.

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?

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.


|s21(a1)|^2 = 50 watts

|s22(a2)|^2 = 50 watts

|b2|^2 = 200 watts

Even in the S-Parameter analysis, superposing two 50W
waves in phase yields 200 watts. Constructive interference
not only makes it possible but demands it.

So not you are superposing power to "yield" a resultant power. Did HP
show you how to do that, or is it all your own work?

Owen

Constructive interference in radiowave propagation
 

A couple of typos fixed:

Cecil Moore wrote in news:0svUh.417$Yo2.402
@newssvr19.news.prodigy.net:

Now let's look at the powers in accordance with HP's
Ap Note 95-1. For that, we don't need to know the Z0.
The beauty of an S-Parameter analysis is that if one
squares the normalized voltages, one gets power.

Cecil,

AN95-1 is a slide show, it is a presentation to accompany a talk, and as
such is incomplete.

Another HP note is AN154 which is derived from a training seminar, but is
more complete in its development. Chapter 1 is relevant to your use of S
parameters.


Let me quote:

Notice that the square of the magnitude of these
new variables has the dimension of power. |a1|^2
can then be thought of as the incident power on
port one; |b1|^2 as power reflected from port one.
These new waves can be called traveling power
waves rather than traveling voltage waves.
Throughout this seminar, we will simply refer to
these waves as traveling waves.

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?

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*ax|^
2.


|s21(a1)|^2 = 50 watts

|s22(a2)|^2 = 50 watts

|b2|^2 = 200 watts

Even in the S-Parameter analysis, superposing two 50W
waves in phase yields 200 watts. Constructive interference
not only makes it possible but demands it.

So now you are superposing power to "yield" a resultant power. Did HP
show you how to do that, or is it all your own work?

Owen