Jim Kelley wrote:

Cecil Moore wrote:
Jim Kelley wrote:
Problem is that it conflicts with the predictions made by the power
propagation model. (The politically correct name is the Joules/sec
propagation model.) That model shows that only a single reflection
of power is needed to explain the whole thing. Of course in some
cases the wave of power has to figure out how to turn around and go
back the other direction after it's been cancelled in order to
conserve energy. (A problem it wouldn't have to solve had it not
violated it in the first place.) Admittedly, some of the details
have yet to be worked out. :-)

Wow Jim, you need to repeat Fields and Waves 310. :-)
You have misunderstood virtually every principle
of the wave reflection model.

I wouldn't presume to take credit for any of the above. I learned it on
r.r.a.a. from someone who I think needs to take Fields and Waves 1. :-)

If you are talking about me, you have either misunderstood
what I said or you enjoy bearing false witness. Here's a quote
from my 2005 magazine article at:

http://www.w5dxp.com/energy.htm

"The author has endeavored to satisfy the purists in this
series of articles. The term "power flow" has been avoided
in favor of "energy flow". Power is a measure of that energy
flow per unit time through a plane. Likewise, the EM fields
in the waves do the interfering. Powers, treated as scalars,
are incapable of interference. Any sign associated with a power
in this paper is the sign of the cosine of the phase angle
between two voltage phasors."

Also, here is an EXCEL spreadsheet version of what happens
during the transient buildup to steady-state.

http://www.w5dxp.com/1secsgat.gif

Do you really consider 30 iterations to be only a single
reflection?
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:

Jim Kelley wrote:


Cecil Moore wrote:

Jim Kelley wrote:

Problem is that it conflicts with the predictions made by the power
propagation model. (The politically correct name is the Joules/sec
propagation model.) That model shows that only a single reflection
of power is needed to explain the whole thing. Of course in some
cases the wave of power has to figure out how to turn around and go
back the other direction after it's been cancelled in order to
conserve energy. (A problem it wouldn't have to solve had it not
violated it in the first place.) Admittedly, some of the details
have yet to be worked out. :-)


Wow Jim, you need to repeat Fields and Waves 310. :-)
You have misunderstood virtually every principle
of the wave reflection model.


I wouldn't presume to take credit for any of the above. I learned it
on r.r.a.a. from someone who I think needs to take Fields and Waves
1. :-)


If you are talking about me, you have either misunderstood
what I said or you enjoy bearing false witness. Here's a quote
from my 2005 magazine article at:

http://www.w5dxp.com/energy.htm

Hi Cecil -

Yes, I'm very familiar with that article. You've already posted a
link to it dozens of times on this newsgroup. It very clearly
illustrates exactly those thing which I may have somewhat more
'colorfully' restated above, and more. It includes equations with
variables for forward and reflected power all throughout, a reference
to a supposed "4th mechanism of reflection" (that's the magical way in
which waves of power and energy change direction), and illustrations
with arrows named Pref showing how power is reflected at impedance
discontinuities.

Back when our corresponence was more cordial, I advised you not to
write those things. And now you'd like to deny having done it; all
the while portraying me as a liar. You're beautiful, man.

73, ac6xg

Jim Kelley wrote:
Yes, I'm very familiar with that article. You've already posted a link
to it dozens of times on this newsgroup. It very clearly illustrates
exactly those thing which I may have somewhat more 'colorfully' restated
above, and more. It includes equations with variables for forward and
reflected power all throughout,

Yes, forward and reflected power measured at a *FIXED* measurement
point. There is no "power flow" anywhere in my article. Energy
does the flowing. Power is the measurement at a *FIXED* measurement
point of that energy flow past that *FIXED* point. Did you note
the use of the word, "FIXED"?

Even though all my references, including the IEEE Dictionary
allow for "power flow", I avoided it in my article as a favor
to you.

a reference to a supposed "4th mechanism
of reflection" (that's the magical way in which waves of power and
energy change direction),

Yes, that may be somewhat original and therefore frightening
for you. Galileo would have scared you to death. If, as Walter
C. Johnson says, interference can *cause* standing waves, it
can probably also cause reflections at an impedance discontinuity
through wave cancellation. You are going to have to do more
than wave your hands to prove otherwise. Not refusing to
answer my questions about my examples would be a good start.

Remember your absolute refusal to compute the total joules/sec
after the first internal reflection arrived at the thin-film
anti-reflective coating in my example? When you learn how to
properly manage irradiance, get back to us.

and illustrations with arrows named Pref
showing how power is reflected at impedance discontinuities.

No! No! No! Power is NOT reflected at an impedance discontinuity.
Those are Poynting vectors. Energy is reflected and that reflected
energy is measured and called "reflected power". Reflected power
is not moving. You continue to get it wrong. The reflected power
is acutally reflected energy measured flowing past a *FIXED* point
near the impedance discontinuity. There are joules in the reflected
wave. The joules in the reflected wave are measured flowing past
a *FIXED* measurement point. But, of course, I have explained
all of this to you before yet you continue bear false witness
after all these years.

Back when our corresponence was more cordial, I advised you not to write
those things. And now you'd like to deny having done it; all the while
portraying me as a liar. You're beautiful, man.

I changed my article just to make you happy. You obviously
have misunderstood, either through lack of processing power,
ignorance, or deliberately. I would guess it is deliberate.
--
73, Cecil http://www.w5dxp.com

On Dec 11, 4:21 pm, Cecil Moore wrote:
Jim Kelley wrote:
Yes, I'm very familiar with that article. You've already posted a link
to it dozens of times on this newsgroup. It very clearly illustrates
exactly those thing which I may have somewhat more 'colorfully' restated
above, and more. It includes equations with variables for forward and
reflected power all throughout,

Yes, forward and reflected power measured at a *FIXED* measurement
point. There is no "power flow" anywhere in my article. Energy
does the flowing. Power is the measurement at a *FIXED* measurement
point of that energy flow past that *FIXED* point. Did you note
the use of the word, "FIXED"?

Even though all my references, including the IEEE Dictionary
allow for "power flow", I avoided it in my article as a favor
to you.

a reference to a supposed "4th mechanism
of reflection" (that's the magical way in which waves of power and
energy change direction),

Yes, that may be somewhat original and therefore frightening
for you. Galileo would have scared you to death. If, as Walter
C. Johnson says, interference can *cause* standing waves, it
can probably also cause reflections at an impedance discontinuity
through wave cancellation. You are going to have to do more
than wave your hands to prove otherwise. Not refusing to
answer my questions about my examples would be a good start.

Remember your absolute refusal to compute the total joules/sec
after the first internal reflection arrived at the thin-film
anti-reflective coating in my example? When you learn how to
properly manage irradiance, get back to us.

and illustrations with arrows named Pref
showing how power is reflected at impedance discontinuities.

No! No! No! Power is NOT reflected at an impedance discontinuity.
Those are Poynting vectors. Energy is reflected and that reflected
energy is measured and called "reflected power". Reflected power
is not moving. You continue to get it wrong. The reflected power
is acutally reflected energy measured flowing past a *FIXED* point
near the impedance discontinuity. There are joules in the reflected
wave. The joules in the reflected wave are measured flowing past
a *FIXED* measurement point. But, of course, I have explained
all of this to you before yet you continue bear false witness
after all these years.

Back when our corresponence was more cordial, I advised you not to write
those things. And now you'd like to deny having done it; all the while
portraying me as a liar. You're beautiful, man.

I changed my article just to make you happy. You obviously
have misunderstood, either through lack of processing power,
ignorance, or deliberately. I would guess it is deliberate.

The debate has never been aoout a little looseness
in the terminology; i.e. does "power flow" or does
"energy flow". That is a straw man of your own
making.

The debate is over much more fundamental issues.

....Keith

Keith Dysart wrote:
The debate has never been about a little looseness
in the terminology;

Actually, I believe that every disagreement between
Jim Kelley and myself has been semantic in nature.
There are no technical fundamentals upon which we
disagree.

We both agree that a light wave from Alpha Centauri
that hits the earth has transferred energy.

We disagree about a light wave from Alpha Centauri
that misses the earth. I say the energy in the light
wave is in the process of being transferred. Jim
disagrees.

The debate is over much more fundamental issues.

Like what? The definition of "transfer"?
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:

Actually, I believe that every disagreement between
Jim Kelley and myself has been semantic in nature.
There are no technical fundamentals upon which we
disagree.

I don't care about your use of words, Cecil. I am only concerned with
some of the concepts that you describe.

73, Jim AC6XG

Jim Kelley wrote:
Cecil Moore wrote:

Actually, I believe that every disagreement between
Jim Kelley and myself has been semantic in nature.
There are no technical fundamentals upon which we
disagree.

I don't care about your use of words, Cecil. I am only concerned with
some of the concepts that you describe.

I use words to describe those concepts. You and I do not
agree on the definitions of those words. Reality is what
it is. It is the different definitions that we are using
that is the problem.

For instance, what if I am using a different definition
than you are for "concepts" in your posting above? What
if you were writing in a language that I didn't understand?
The outcome would be similar to what we have now.
--
73, Cecil http://www.w5dxp.com

Jim Kelley wrote:
I am only concerned with
some of the concepts that you describe.

When you repeat those concepts back to me, they bear
no resemblance to the concepts that I am trying to
describe. That is proof that our disagreements are
semantic. (The only other possibility is that you
are unethical and are deliberately bearing false
witness against me.)

I use words to describe my concepts. You and I do not
agree on the definitions of those words. Reality is what
it is. It is the different definitions that we are using
that is the problem. "Transfer" is obviously one of those
words. I say all EM waves transfer energy. You say not
all EM waves transfer energy. It is simply that we are
using different definitions of the word "transfer".
There are many other words for which we have different
definitions.

You and I might as well be trying to communicate in two
foreign languages that neither one of us understand.
--
73, Cecil http://www.w5dxp.com

Keith Dysart wrote:
The debate is over much more fundamental issues.

I guess that depends upon the definition of
"fundamental" doesn't it? :-) Hint: Virtually
every verbal disagreement is semantic.
--
73, Cecil http://www.w5dxp.com

Keith Dysart wrote:

On Dec 9, 9:36 pm, Roger wrote:



The constantly-in-phase traveling wave concept requires the difficult-to-believe observation that a directional ammeter placed very near the end of an open transmission line will read the same current as if it were placed at the source end. Perhaps someone can perform that experiment some day, but I can not imagine how it can be done without placing a load on the line, thus invalidating the initial assumptions.



The experiment will show the expected result but will not help understand why. For that, examination of the measurements and arithmetic performed by a directional ammeter is useful. Below, all voltages and currents are instantaneous. Total voltage, Vt = Vf + Vr Total current, It = If - Ir Vf = If * Z0 Vr = Ir * Z0 Substituting.... Vt = (If + Ir) * Z0 Ir = Vt/Z0 - If If = It + Ir If = It + (Vt/Z0 - If) If = (It + Vt/Z0)/2 Similarly, Ir = (It - Vt/Z0)/2 The directional ammeter measures instantaneous Vt and It, does the above arithmetic and presents If. A directional ammeter that presents a single number rather than the time varying If has probably converted the instantaneous values to RMS. Examing It and Vt at various points on the line and doing the above arithmetic will reveal why the same value for If is obtained everywhere. Directional wattmeters are more common than directional ammeters. A directional wattmeter does the above arithmetic then squares If, multiplies by Z0 and presents the results in watts. All this from just measuring Vt and It. ....Keith

Hi Keith,

Thanks to you and others for responding on this side issue.   It was very helpful to me and resulted in a vast improvement in how I understood the theory behind directional watt meters.  I had the misconception that current pickup over some lineal distance of transmission line was NECESSARY for the device to work, but now clearly understand that instantaneous measurement points suffice (and that instantaneous current measurement may be impossible).

After considerable thought, I think the math you presented above is for one of two cases of reflective waves, the reflection from a higher  impedance load.   When the load is less than the Zo of the line, the currents add but voltages subtract.   Right?  The end result is the same for both cases.

To elaborate,  the power (Pt) resident on the transmission line will always be the sum of forward power and reflected power.  Mathematically:

Ptotal = Pf + |Pr|
Pt = If * Vf  +  |(-Ir * Vr)|   (Case of load impedance greater than line impedance) (Case 1)
or
Pt =  If * Vf  +  |(Ir  *  - Vr)|  (Case of load impedance less than line impedance) (Case 2)

Notice that Pt is always the ABSOLUTE SUM of the two power terms because the reflective power always carries a negative sign on either the current or voltage term.  As a result, the summed  value of the resident power on a mismatched line is always greater than the actual power going to the load.  

Your example was correct for Case 1.   I will show only Case 2.

Vt = Vf - Vr
It = If + I r

Vf = If * Z0
Vr = Ir * Z0

Substituting...

Vt = (If - Ir) * Z0
Ir = If - Vt / Z0

If = It - Ir
If = It - If + Vt/Z0
If = (It + Vt/Z0)/2

Similarly, Ir = (It - Vt/Z0)/2

The results are the same for both Case 1 and Case 2.

Agreed?

73, Roger, W7WKB