Revisiting the Power Explanation
 

Cecil Moore wrote:


So you need to go off and argue with Jim over the
definition of "power". Instead of talking about power,
Jim has convinced me to talk about watts or joules/sec
which he says are not necessarily power. The confusion
comes from the field of physics, not from me. While you
are talking to Jim, get him to explain the definition
of "transfer".

For a thorough understanding of the physical meaning that word, I
suggest working a few rigorous thermodynamics problems.

73, ac6xg

Revisiting the Power Explanation
 

On Mar 25, 4:23 pm, Cecil Moore wrote:
If reflected energy is not dissipated, it undergoes destructive
interference and is redirected back toward the load as constructive
interference instead of being incident upon the source. Why
are you having difficulty with that concept from page 388
of "Optics", by Hecht, 4th edition?

Hi Cecil,

Dissipation and interference are not interdependent phenomena.
Moreover, destructive interference does not "redirect" or otherwise
cause anything to happen. Intereference is nothing more than a means
for describing the result of the superposition of waves.

73, ac6xg

Revisiting the Power Explanation
 

Richard Harrison wrote:
Walter Maxwell, W2DU wrote:
"When the matching is accomplished the phase relationship between the
forward and reflected voltages can either be 0 degrees or 180 degrees,
resulting in a total re-reflection of the voltage. If the resultant
voltage is 0 degrees, then the resultant current is 180 degrees, thus
voltage sees a virtual open circuit and the current sees a virtual sees
a virtual short circuit. The result is that the reflected voltage and
current are totally re-reflected IN PHASE with the source voltage and
current. This is the reason the forward power in the line is greater
than the source power when the line is mismatched at the load, but where
the matching device has re-reflected the reflected waves."

Eloquently stated and significant because there are many who would swear
that a properly matched transmitter re-reflects the reflected waves, but
don`t have a clue as to why.

Best regards, Richard Harrison, KB5WZI

Walt doesn't actually indicate 'why' here, either. He is reciting a
set of well known circumstances, and implying that one set of facts
results in another. While the facts are obviously correct, any cause
and effect relationship between them must be inferred. It is not
demonstrated. The fact that every time a visitor stands at my front
door the bell rings is not proof that standing at my front door
*causes* the bell to ring.

The behavior of electromagnetic waves and their interaction with
matter as described by JC Maxwell and others already provides
satisfactory and sufficient explanation for the phenomenon of
reflectivity. That should not be overlooked here.

73, ac6xg

Revisiting the Power Explanation
 

Gene Fuller wrote:
Utter nonsense. Jim was pulling your chain, and I guess you fell for it.

Perhaps your argument is with Jim.
--
73, Cecil http://www.w5dxp.com

Revisiting the Power Explanation
 

Keith Dysart wrote:
Now all we need is a single example for which the equality
does not hold and "Cecil's Hypothesis" will be disproved.

Cecil's hypothesis is that the conservation of energy
principle is valid. All you need is a single example for
which the conservation of energy principle does not hold.

Remember, the magnitude of energy in a transmission line
is *EXACTLY* the amount of energy needed to support
the forward joules/sec and the reflected joules/sec.
--
73, Cecil http://www.w5dxp.com

Revisiting the Power Explanation
 

Jim Kelley wrote:
Moreover, destructive interference does not "redirect" or otherwise
cause anything to happen.

May I direct you to page 388 of "Optics" by Hecht
where he asserts that total destructive interference
must be matched by an equal magnitude of total
constructive interference. Since there are only two
possible directions in a transmission line, total
destructive interference in one direction must be
matched by an equal magnitude of total constructive
interference in the opposite direction. From my
energy analysis article, a reference:

http://micro.magnet.fsu.edu/primer/j...ons/index.html

"... when two waves of equal amplitude and wavelength that are
180-degrees ... out of phase with each other meet, they are not
actually annihilated, ... All of the photon energy present in
these waves must somehow be recovered or redistributed in a
new direction, according to the law of energy conservation ...
Instead, upon meeting, the photons are redistributed to regions
that permit constructive interference, ..."

This is a very tough question: In a transmission line with only
two directions reckon what "redistributed in a new direction"
would necessarily mean? :-)
--
73, Cecil http://www.w5dxp.com

Revisiting the Power Explanation
 

Jim Kelley wrote:
For a thorough understanding of the physical meaning that word, I
suggest working a few rigorous thermodynamics problems.

What is your response for Gene's assertion that you
are pulling my leg about all of this?
--
73, Cecil http://www.w5dxp.com

Revisiting the Power Explanation
 

Jim Kelley wrote:
Walt doesn't actually indicate 'why' here, either. He is reciting a set
of well known circumstances, and implying that one set of facts results
in another. While the facts are obviously correct, any cause and effect
relationship between them must be inferred.

From his writings in "Reflections" and his postings
here, Walt obviously understands destructive and
constructive interference and the fact that (from
the Florida State University site):

"... All of the photon energy present in
these (cancelled) waves must somehow be recovered or
redistributed in a new direction, according to the
law of energy conservation ..."

In a transmission line we have two directions.
1. Toward the load
2. Toward the source

When the "photon energy" is "redistributed in a new
direction" in a transmission line, I'll bet it
goes in exactly the direction that Walt says it
goes.
--
73, Cecil http://www.w5dxp.com

Revisiting the Power Explanation
 

Cecil Moore wrote in news:ZbBOh.19326$uo3.18213
@newssvr14.news.prodigy.net:

Remember, the magnitude of energy in a transmission line
is *EXACTLY* the amount of energy needed to support
the forward joules/sec and the reflected joules/sec.

Cecil,

If you go beyond your (unqualified) average view of the world and drilled
down on the fields in the line as a function of time and position, and
their relationship with steady state real and reactive energy flow at each
end of the line in the general case, it may provide you with a more correct
view of the tranmission line and its load and source in your favoured
energy context.

Owen

Revisiting the Power Explanation
 

Cecil Moore wrote in news:1qBOh.19329$uo3.12743
@newssvr14.news.prodigy.net:

What is your response for Gene's assertion that you
are pulling my leg about all of this?

The games people play. Wasn't this one called something like 'lets you and
him have a fight'.

Owen