Richard Harrison wrote:
Jim Kelley wrote:
"In other words a system in which all of the power from the source
reaches the load and none is reflected back to the source without first
reflecting then re-reflecting would violate conservation of energy."

Conservation of energy means that energy is neither created nor
destroyed, but that heat and other forms of energy are quantitifiable
and convertable in their equivalence. The total amount of mechanical,
thermal, chemical, electrical, and other forms of energy in any isolated
system remains constant. A century ago, Einstein broadened the law to
include equivalence of mass and energy.

Regardless of reflections and re-reflections, all the energy sourced
into a transmission line ends up in the load if it isn`t lost in
transmission by radiation or conversion into heat. There`s no place else
for it to go.

Best regards, Richard Harrison, KB5WZI

Yes, thanks Richard. It is quite a simple concept. But my contention
really isn't about conservation of energy. It's about the 2nd law of
thermodynamics. Nature does not require a rolling ball to run through a
Rube Goldberg contraption in order to conserve energy. In fact it
generally abhors such things. "One should not increase, beyond what is
necessary, the number of entities required to explain anything."

73, ac6xg

Cecil Moore, W5DXP is alleged to have written:
"Nor will we find a negative scalar quantity accompanied by the claim
that the negative sign indicates a change in direction as you have
done."

Have not read Hscht, but I`ve read Terman and realize that a
transmission line can guide a wave only forward and backward. Sometimes
backward is considered the negative direction.

Terman gives an example on page 90 of his 1955 edition:
"When the load end of the line is shorted, that is Eload =0 , reference
to Eq. (4-14) shows the reflection coefficient has the value -1.0 on an
angle of 0-deg.= 1.0 on an angle of 180-deg. As in the open-circuited
case, the reflected wave has an amplitude equal to the amplitude of the
incident wave. However, the refleection now takes place with a reversal
in phase of the voltage and without change in phase of the current."

Best regards, Richard Harrison, KB5WZI

Jim Kelley wrote:
"It`s about the 2nd law of thermodynamics."

Which a
1. You can`t win.
2. You can`t break even.
3. You can`t get out of the game.

Best regards, Richard Harrison, KB5WZI

Richard Harrison wrote:

Cecil Moore, W5DXP is alleged to have written:

Jim Kelley actually claims to have written it.

"Nor will we find a negative scalar quantity accompanied by the claim
that the negative sign indicates a change in direction as you have
done."

Have not read Hscht, but I`ve read Terman and realize that a
transmission line can guide a wave only forward and backward. Sometimes
backward is considered the negative direction.

Yes, for vector quantities expressed as a function of position or time.

Terman gives an example on page 90 of his 1955 edition:
"When the load end of the line is shorted, that is Eload =0 , reference
to Eq. (4-14) shows the reflection coefficient has the value -1.0 on an
angle of 0-deg.= 1.0 on an angle of 180-deg. As in the open-circuited
case, the reflected wave has an amplitude equal to the amplitude of the
incident wave. However, the refleection now takes place with a reversal
in phase of the voltage and without change in phase of the current."

From Webster's Collegiate:
Scalar - a quantity such as mass or time that has a magnitude
describable by a real number and no direction

Power as a scalar quantity does not have direction, and so one could not
for example subtract power 'moving' in one direction from power 'moving'
in the other direction by arbitrarily multiplying one of the magnitudes
by negative one.

73, ac6xg

Richard Harrison wrote:
Cecil Moore, W5DXP is alleged to have written:

Actually, it was Jim Kelley who wrote the following.

"Nor will we find a negative scalar quantity accompanied by the claim
that the negative sign indicates a change in direction as you have
done."

Have not read Hecht, but I`ve read Terman and realize that a
transmission line can guide a wave only forward and backward. Sometimes
backward is considered the negative direction.

Yep, that's what I told him. In fact, Ramo & Whinnery illustrate
the Poynting vector for forward power as Pz+ and the Poynting
vector for reflected power as Pz-. The net power is (Pz+)-(Pz-).
--
73, Cecil http://www.qsl.net/w5dxp


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Jim Kelley wrote:
Power as a scalar quantity does not have direction, and so one could not
for example subtract power 'moving' in one direction from power 'moving'
in the other direction by arbitrarily multiplying one of the magnitudes
by negative one.

For engineers, the direction of the arrow for the Power
Flow Vector in joules/sec is generally accepted to be the
same as the direction of the joules.

From the IEEE Dictionary: "power-flow vector - Vector-
characterizing energy propagation caused by a wave and
giving magnitude and direction of power per unit-area
propagating in the wave."

Please note the "*DIRECTION OF POWER* ... *PROPAGATING*
in the wave", a direct contradiction to your above assertion.
The power measured at the source somehow finds its way to the
load in spite of not having any direction (according to you. :-)

Most of your rantings and ravings over what I have said
are simply semantics and definitions. RF energy and RF
power are so closely related that Walter C. Johnson talks
about the "principle of conservation of power".
--
73, Cecil http://www.qsl.net/w5dxp


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Jim Kelley wrote:
"Power as a scalar quantity does not have direction, and so one could
not for example subtract power "moving" in the other direction by
arbitrarily multiplying by negative one."

Terman did so rather deftly. We make simplifying assumptions and replace
the general case with the special case all the time. Bird defines true
power delivered by the source to the load as the difference between its
forward and reverse power indications. It`s satisfactory in most cases.

Inductive and capacitive reactances are routinely added together to give
the net reactance and it works fine so long as the reactances are pure.
They lie on the same axis but in opposite directions so can be treated
as scalars. Another special case.

Best regards, Richard Harrison, KB5WZI

On Tue, 19 Jul 2005 23:05:57 -0500, (Richard
Harrison) wrote:

Bird defines true
power delivered by the source to the load as the difference between its
forward and reverse power indications. It`s satisfactory in most cases.

Hi Richard,

That's because the vector arrow is printed on the knob. You won't
find a vector notation in the math that has been bandied about because
it deals with Scalars and Phase independently (and absolutely no
direction expressed whatever).

Any introduction of direction is purely an invention unsupported by
references so far expressed. However having pointed this out, like
the multitude of mistakes that have gone before it, is not going to
change the pantomime.

Marcel can go through the motions of wiping the window clean, but
there's no glass there. ;-)

73's
Richard Clark, KB7QHC

Richard Clark wrote:
Any introduction of direction is purely an invention unsupported by
references so far expressed.

You must have missed the IEEE Definition of "power flow vector".
It speaks of "power ... propagating in the wave". Here's another
definition from the IEEE Dictionary:

"power vector - ... a vector whose magnitude is equal to the
apparent power ..." A power vector diagram in three dimensions
appears with this definition along with its direction. There
is a vector for distortion power, reactive power, and active
power, all orthogonal to each other, vectorally adding up to
the total power vector. I'll bet you are rolling Hecht's or
Einstein's eyes again at the concept of "reactive power".

These definitions are conventions from various fields of
engineering. One is not wrong and the other right. They are
simply context based definitions. English is NOT a context
free language. You have your own little sacred cow definitions
from pure physics but please don't try to force them on the rest
of the world. (You would probably say the definition of power in
Chinese is wrong because you can't read it.)

A power company engineer would be confused about your concept of
how the power generated by the generation plant cannot get to the
consumer hundreds of miles away. Ask him what is in his
transmission lines and he will say power, some of it reactive.

Some RF engineers are confused about your concept of how the
power generated by the transmitter cannot get to the antenna.
In fact, if the transmission line is one microsecond long,
the same power measured at the transmitter makes it to the
antenna one microsecond later minus losses. Some incident power
may be rejected by a mismatched load as reflected power, which
is incident upon the source one microsecond later minus losses.
--
73, Cecil http://www.qsl.net/w5dxp

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On Wed, 20 Jul 2005 08:13:42 -0500, Cecil Moore
wrote:
A power company engineer would be confused
You know some pretty stupid engineers - from the binary field?
P= I²R
Which one is the vector?
P=E²/R
Which one is the vector?

Does your power company deliver your 60Hz via laser? Or do they use a
Log Periodic Array? A transmission line like the zip cord to your
lamp? What is the characteristic Z of that transmission line? Is it
matched to the load? To the source?

Sorry to ask all these basic questions so far beyond your ability to
render into TTL. No doubt we will get many explanations but no
answers.