Richard Clark wrote:

Cecil Moore wrote:
100W XMTR---50 ohm---+---one second long 291.5 ohm---50 ohm load

And yet more violations of Initial Condition.

The question was: Where are those 300 joules of EM RF energy
that have been previously sourced by the XMTR but not yet dissipated
in the load?

What are you afraid of that would be contained in your straight
answer to that simple question? Doesn't it embarrass you to
present all sorts of logical diversions instead of answering?
--
73, Cecil http://www.qsl.net/w5dxp

Ian White, G3SEK wrote:

Cecil Moore wrote:
The RF technician I worked with at Intel was directed by his manager to
report all powers in dB referenced to the signal generator output ...

Since his manager was Cecil, there may be a good case for worker's comp.

Actually, his manager was one Mr. Smith, a ham with a Canadian call.
Is it unusual for dB figures to be referenced to the signal generator
output?
--
73, Cecil http://www.qsl.net/w5dxp

On Thu, 02 Dec 2004 08:45:15 -0600, Cecil Moore
wrote:
Signal Generator Output Power is measured and all
dB measurements are referenced to that power.
Yet another violation of Initial Conditions. Signal Generator outputs
are calibrated into a 50 Ohm Load. Another violation of Initial
Conditions is that Signal Generators do not source 100W.

Roy Lewallen wrote:
I strongly suggest forgetting completely about "forward" and "reverse"
power. If you must deal with directional waves, look at forward and
reverse voltage and current waves.

Say Roy, exactly how many of those EM voltage and current waves
have you encountered that didn't possess any energy? I always
thought the power in an EM wave was defined as ExH. :-)
--
73, Cecil http://www.qsl.net/w5dxp

On Thu, 02 Dec 2004 08:32:27 -0600, Cecil Moore
wrote:
directed by his manager to report all powers in dB referenced to the
signal generator output which, in the above example, was 100 watts
Betcha can't name the model number or maker.

On Thu, 02 Dec 2004 10:32:29 -0600, Cecil Moore
wrote:
definition of an Initial Condition violation:
The question was
Different this time than last (recurse here)

On Thu, 02 Dec 2004 10:23:14 -0600, Cecil Moore
wrote:
I know you consider it unfair to your position
Sitting down? Or are you talking about chiropodistry?

Richard Clark wrote:

On Thu, 02 Dec 2004 08:45:15 -0600, Cecil Moore
wrote:

Signal Generator Output Power is measured and all
dB measurements are referenced to that power.

Yet another violation of Initial Conditions. Signal Generator outputs
are calibrated into a 50 Ohm Load.

In a signal generator equipped with a circulator/load, the signal
generator indeed does always see close to a 50 ohm load so, no
problem.

Another violation of Initial
Conditions is that Signal Generators do not source 100W.

Hams understand 100W and since this was a mental exercise,
I used 100W. If I had used 10 dBm, I would have lost most
of the readers.

Richard, I don't recall an "Initial Conditions List". Perhaps
you could point me to the posting that listed them. Who is the
"Initial Conditions" God, anyway?
--
73, Cecil http://www.qsl.net/w5dxp

Richard Clark wrote:

Cecil Moore wrote:
directed by his manager to report all powers in dB referenced to the
signal generator output which, in the above example, was 100 watts

Betcha can't name the model number or maker.

Hint: If it's not obvious, the signal generator used at Intel
in Chandler, AZ during the 1990's and the signal generator used
in my purely mental exercise posted to r.r.a.a in 2004 are NOT
the same device. Sheeeezzzzzz ...
--
73, Cecil http://www.qsl.net/w5dxp

On Thu, 02 Dec 2004 10:51:48 -0600, Cecil Moore
wrote:

|Ian White, G3SEK wrote:
|
| Cecil Moore wrote:
| The RF technician I worked with at Intel was directed by his manager to
| report all powers in dB referenced to the signal generator output ...
|
| Since his manager was Cecil, there may be a good case for worker's comp.
|
|Actually, his manager was one Mr. Smith, a ham with a Canadian call.
|Is it unusual for dB figures to be referenced to the signal generator
|output?

Highly.

All of the S-parameters I've ever measured were referenced to the ends
of the cables used to connect the DUT to the test equipment.

Absent concerns about SNR, I didn't give a rat's behind about what the
signal generator power was.

On Thu, 02 Dec 2004 11:47:36 -0600, Cecil Moore
wrote:
If I had used 10 dBm, I would have lost most of the readers.
You lost them at 100W

On Thu, 02 Dec 2004 12:14:58 -0600, Cecil Moore
wrote:
Betcha can't name the model number or maker.
Hint: If it's not obvious
I Win! You can't name them at Intel OR ARRL! :-)
Another violation of Initial Conditions

Wes Stewart wrote:
All of the S-parameters I've ever measured were referenced to the ends
of the cables used to connect the DUT to the test equipment.

Where the signal generator was connected?

b1 = s11*a1 + s12*a2

The HP S-parameter Ap Note 95-1 sez:

|a1|^2 = Power incident on the input of the network
= Power available from a source impedance Z0

What was |a1|^2 referenced to?
--
73, Cecil http://www.qsl.net/w5dxp

On Thu, 02 Dec 2004 12:55:58 -0600, Cecil Moore
wrote:
Apparently two separate concepts in the same sentence
are just too much for you to comprehend.
Which:
1. You can't name the model/maker of this supposed Intel source
or
2. You can't name the model/maker of this supposed ARRL source
?

Suppositions and guessing are hallmarks of Initial Conditions
violation.

Richard Clark wrote:
I Win! You can't name them at Intel OR ARRL! :-)
Another violation of Initial Conditions

Apparently two separate concepts in the same sentence
are just too much for you to comprehend.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil,

It's a slow day, so I thought I might take some time to help you out of
your dilemma.

Q: Where are the missing joules?

A: They are associated with the large standing wave supported by the
mismatched terminations of your transmission line.

As I have pointed out previously, standing waves are not inert. The
shape of the wave does not travel down the line, but the fields are
changing, and the charges are moving. Within each loop of the standing
wave the stored energy simply oscillates between magnetic energy when
the current is high and electrostatic energy when the voltage is high.
Very basic stuff.

The problem in your analysis is the initial axiom that RF waves always
move. This is simply incorrect, and it leads to the dilemma you face.
Traveling waves are fine if you do the math correctly, but the physical
situation is in the form of a standing wave. The model results need to
agree or there is a math error.

And as many people have pointed out, always add the voltages and
currents first and only consider power at the very end of the analysis.

Since you are also an optics guru you might want to check into the
details of laser cavity operation or Fabry-Perot etalon operation. These
are highly mismatched systems with very strong standing wave components
along with a little bit of net traveling wave. Definitely related to the
problem you posed.

73,
Gene
W4SZ


Cecil Moore wrote:

[snip]

After steady-state has been reached, the XMTR has output 300 more
joules than the load has accepted. A smaller real-world experiment
will easily verify that it is a fact that all energy sourced that
has not reached the load must necessarily be confined to circulating
energy or losses in the transmission line.

Question: In the above example, where are those 300 joules of energy
located and what is happening to them?

We know that 300 joules is wave energy and RF waves always move
at the speed of light, i.e. they cannot stand still. So please
determine how much energy is moving and in which of only two
possible directions.

Richard Clark wrote:

On Wed, 01 Dec 2004 21:27:25 -0800, Jim Kelley
wrote:


The confusion I think stems from the contention that any 'reflected
power' (unfortunate nomenclature IMO) is first sourced and then after
reflection returned back into the source, or to a circulator load as the
case may be. The latter case is certainly correct. The former is
phenomenologically problematic.


Hi Jim,

By that same logic it follows that the power "into" the transmission
line was in fact never "into" the line at all but into the circulator
input, and any power finding its way into the circulator load also
never found its way into the line, but was merely reflected at the
circulator/line interface.

A circulator, being in general a three (or four) port directional
device, might have some trouble buying into that logic. ;-) The crux of
the phenomenological problem is that power does not flow or move, nor is
it something that is reflected. Hence Roy's (and Reg's) suggestion that
the voltages and currents resulting from the fields which propagate must
be analyzed. From that analysis (which involves the fields, or V and I,
propagating, reflecting, and interfering in both directions) one can
determine the quantities of energy being absorbed by the effected
dissipative loads in the circuit.

A transmission line circuit which includes a circulator w/load does
indeed provide a mechanism by which a portion of the energy produced by
a source can effectively be reflected from a mismatched load back toward
the generator. On encountering the circulator in the reverse direction,
it is then directed to the circulator load where it can be dissipated.
In a lossey transmission line, that reflected signal will be attenuated
and would in fact increase the total amount of energy the transmission
line dissipates. The amount of energy produced by the generator
increases by the amount lost to the circulator load and the transmission
line. **Absent the circulator, those energy losses would not be
realized - nor sourced.**

The argument that fields "have" or "contain" energy is misdirected and
misapplied. Obviously one can measure a field at each of the electrical
outlets in his house even when nothing is drawing energy from those
outlets. The potential to create a transfer of energy does not
necessarily equate with a transfer of energy. A mechanism must exist
which provides the conduit for a transfer of energy. It is that
mechanism, and the nature of the source and the load which determine the
amount of power being generated and transferred to the dissipating load.

73, Jim AC6XG

Richard Clark wrote:
Which:

One last time:
The 100 watts came from a MENTAL signal generator existing ONLY in
my IMAGINATION for the propose of discussing a HYPOTHETICAL example
on r.r.a.a. I'm sorry you are having difficulty understanding that
concept. Perhaps English lessons would help?
--
73, Cecil http://www.qsl.net/w5dxp

On Thu, 02 Dec 2004 13:38:05 -0600, Cecil Moore
wrote:
One last time:
Actually there is no last time unless:
1. You can't name the model/maker of this supposed Intel source
or
2. You can't name the model/maker of this supposed ARRL source
?
Choose one or both.
Suppositions and guessing are hallmarks of Initial Conditions
violation.

Cecil,

Radio amateurs and "magic antenna" charlatans love to abuse Poynting
vectors and the Poynting theorem.

The basic answer is no, it is not correct to say, "the power in an EM
wave was [is] defined as ExH."

The Poynting vector, generally described as ExH, is the energy flow
density. It has units of energy/area/time. While this may seem to be
nitpicking it is essential to note that this vector is defined at a
point, not for a "wave", and an integration (or summation) over the
surface of a closed volume must be performed before one can say anything
about power or conservation of energy.

In practical terms the Poynting vector ExH and the Poynting theorem have
little utility for radio amateurs.

73,
Gene
W4SZ

Cecil Moore wrote:

Roy Lewallen wrote:

I strongly suggest forgetting completely about "forward" and "reverse"
power. If you must deal with directional waves, look at forward and
reverse voltage and current waves.


Say Roy, exactly how many of those EM voltage and current waves
have you encountered that didn't possess any energy? I always
thought the power in an EM wave was defined as ExH. :-)
--
73, Cecil http://www.qsl.net/w5dxp

Gene Fuller wrote:
Q: Where are the missing joules?

A: They are associated with the large standing wave supported by the
mismatched terminations of your transmission line.

The "large standing wave" is associated with a an EM forward wave
traveling at the speed of light superposed with an EM reflected
wave traveling at the speed of light. Please give us an example
of an EM standing wave that is not composed of superposed EM waves
traveling in opposite directions at the speed of light.

What you seem to be saying is that two similar vehicles traveling
in opposite directions at the same speed don't possess any net
energy. Try standing between them when they crash and get back
to us.

As I have pointed out previously, standing waves are not inert. The
shape of the wave does not travel down the line, but the fields are
changing, and the charges are moving. Within each loop of the standing
wave the stored energy simply oscillates between magnetic energy when
the current is high and electrostatic energy when the voltage is high.
Very basic stuff.

Very magic stuff. EM waves simply cannot slosh around side-to-side
in a transmission line. EM waves must move at the speed of light or
else the theory of relativity is wrong. You are mentally lumping
things together in your mind when they are not lumpable together in
reality, i.e. your thoughts don't match reality.

The only time two EM waves traveling in opposite directions interact
is at an impedance discontinuity. All other interaction exists only
in your mind, not in reality. In a constant Z0 environment, EM waves
traveling in different directions pass like ships in the night.

The problem in your analysis is the initial axiom that RF waves always
move. This is simply incorrect, and it leads to the dilemma you face.

Please give me an example of just one photon that doesn't move at
the speed of light. You will have proven the theory of relativity to
be incorrect.

And as many people have pointed out, always add the voltages and
currents first and only consider power at the very end of the analysis.

Please don't pass yourself off as an expert on a subject where your
only recommendation is not to think about the subject. It reminds me
of the priests who put Galileo under house arrest.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil,

Fine.

My method solves the problem. Your method leads to endless threads on RRAA.

Have it your way.

73,
Gene
W4SZ

Cecil Moore wrote:

Gene Fuller wrote:

Q: Where are the missing joules?

A: They are associated with the large standing wave supported by the
mismatched terminations of your transmission line.


The "large standing wave" is associated with a an EM forward wave
traveling at the speed of light superposed with an EM reflected
wave traveling at the speed of light. Please give us an example
of an EM standing wave that is not composed of superposed EM waves
traveling in opposite directions at the speed of light.

What you seem to be saying is that two similar vehicles traveling
in opposite directions at the same speed don't possess any net
energy. Try standing between them when they crash and get back
to us.

As I have pointed out previously, standing waves are not inert. The
shape of the wave does not travel down the line, but the fields are
changing, and the charges are moving. Within each loop of the standing
wave the stored energy simply oscillates between magnetic energy when
the current is high and electrostatic energy when the voltage is high.
Very basic stuff.


Very magic stuff. EM waves simply cannot slosh around side-to-side
in a transmission line. EM waves must move at the speed of light or
else the theory of relativity is wrong. You are mentally lumping
things together in your mind when they are not lumpable together in
reality, i.e. your thoughts don't match reality.

The only time two EM waves traveling in opposite directions interact
is at an impedance discontinuity. All other interaction exists only
in your mind, not in reality. In a constant Z0 environment, EM waves
traveling in different directions pass like ships in the night.

The problem in your analysis is the initial axiom that RF waves always
move. This is simply incorrect, and it leads to the dilemma you face.


Please give me an example of just one photon that doesn't move at
the speed of light. You will have proven the theory of relativity to
be incorrect.

And as many people have pointed out, always add the voltages and
currents first and only consider power at the very end of the analysis.


Please don't pass yourself off as an expert on a subject where your
only recommendation is not to think about the subject. It reminds me
of the priests who put Galileo under house arrest.
--
73, Cecil http://www.qsl.net/w5dxp

Jim Kelley wrote:
The crux of
the phenomenological problem is that power does not flow or move, nor is
it something that is reflected.

But energy does flow and move and is something that can be reflected.
You can easily see the energy packets using a TDR. Without energy,
those pulses wouldn't exist. The energy is obviously in the pulse,
where the voltage and current are.

And joules of energy flowing past a point is joules/sec, i.e. power,
by IEEE definition.

Incidentally, how do you explain the Poynting Vector and the Power
Flow Vector?

The argument that fields "have" or "contain" energy is misdirected and
misapplied.

A lot of people will be surprised to discover that their electromagnetic
ExH and ExB values are "misdirected and misapplied".
--
73, Cecil http://www.qsl.net/w5dxp

Gene Fuller wrote:
The Poynting vector, generally described as ExH, is the energy flow
density. It has units of energy/area/time.

Rate of energy flow through an area? Sure sounds like joules/sec
(power) to me. The IEEE Dictionary agrees.

In practical terms the Poynting vector ExH and the Poynting theorem have
little utility for radio amateurs.

I particularly like Johnson's treatment where the forward power
and reflected power have separate Poynting Vectors. :-)

A quote from Ramo & Whinnery's, _Fields_and_Waves_:

"... it is often convenient to think of the Poynting Vector as
the vector giving direction and magnitude of energy flow at any
point in space."
--
73, Cecil http://www.qsl.net/w5dxp

On Thu, 02 Dec 2004 11:25:32 -0800, Jim Kelley
wrote:

A circulator, being in general a three (or four) port directional
device, might have some trouble buying into that logic. ;-) The crux of
the phenomenological problem is that power does not flow or move, nor is
it something that is reflected.

Hi Jim,

I merely responded in like metaphors.

To this point, the meditation of the difference between Bob's results
and the ARRL table speculates that the ARRL used an unknown Intel 100W
circulating Signal Generator driving 1 second's worth of transmission
line where Poynters Theorem proves that the dB loss is - well, we
never get to the end, do we?

73's
Richard Clark, KB7QHC

Richard Clark wrote:

On Thu, 02 Dec 2004 11:25:32 -0800, Jim Kelley
wrote:


A circulator, being in general a three (or four) port directional
device, might have some trouble buying into that logic. ;-) The crux of
the phenomenological problem is that power does not flow or move, nor is
it something that is reflected.


Hi Jim,

I merely responded in like metaphors.

I had a hunch about that. But I can't always parse your sentences into
the form of a concrete idea. Usually an interesting read though. ;-)

To this point, the meditation of the difference between Bob's results
and the ARRL table speculates that the ARRL used an unknown Intel 100W
circulating Signal Generator driving 1 second's worth of transmission
line where Poynters Theorem proves that the dB loss is - well, we
never get to the end, do we?

That's absolutely right. Not all of us do. When some of us have a
question about something, we respond by flinging poison tipped daggers
at those who, in the persuit of a common interest, try to help us
achieve a more cogent understanding.

73, Jim AC6XG

Gene Fuller wrote:
My method solves the problem. Your method leads to endless threads on RRAA.

Your method doesn't begin to solve the problem of tracking
the energy through the system. In fact, it specifically avoids
tracking the energy. My method has made a certain amount of
progress in the direction of understanding energy flow. The key
seems to be that for every case of constructive interference,
there must exist an equal magnitude of destructive interference,
as asserted by Hecht, in _Optics_.
--
73, Cecil http://www.qsl.net/w5dxp

On Thu, 02 Dec 2004 14:46:34 -0600, Cecil Moore
wrote:
Gene Fuller wrote:
...energy/area/time.
sounds like joules/sec (power) to me. The IEEE Dictionary agrees.
If so, then a strange dictionary indeed (or strange reader),
Gene's term reduces to energy·time·area^-1 not energy·time^-1

What kind of sound was that anyway?

On Thu, 02 Dec 2004 13:10:18 -0800, Jim Kelley
wrote:

When some of us have a
question about something, we respond by flinging poison tipped daggers
at those who, in the persuit of a common interest, try to help us
achieve a more cogent understanding.

Hi Jim,

Talk about parsing. Which way are the daggers flying today?

I hope explaining doesn't require the theory of optics or someone's
eye will be put out. ;-(

73's
Richard Clark, KB7QHC

Richard Clark wrote:

On Thu, 02 Dec 2004 14:46:34 -0600, Cecil Moore
wrote:

Gene Fuller wrote:

...energy/area/time.

sounds like joules/sec (power) to me. The IEEE Dictionary agrees.

If so, then a strange dictionary indeed (or strange reader),
Gene's term reduces to energy·time·area^-1 not energy·time^-1

Every thorough discussion of the Poynting Theorem stresses the caveat
that Gene poynted out.

Born and Wolf does observe that the Poynting vector is adequately
defined as the "density of the energy flow", "the amount of energy which
crosses a boundary surface per second a unit area normal to the
directions of E and H." They add however:
"It should be noted that the interpretation of S as energy flow (more
precisely as the density of the flow) is an abstraction which introduces
a certain degree of arbitrariness. For the quantity which is physically
significant is, according to (41) [an expression for the rate of change
of energy within a volume], not S itself, but the integral of S . n
taken over a _closed_ surface." Emphasis on 'closed' is mine.

They also point out that the integral of the Poynting vector over an
arbitrary volume which contains no radiator or absorber of energy, or
where no mechanical work is done, is equal to zero. They cite
conservation of energy as the directive.

73, Jim AC6XG

Richard,

Your point is correct of course, but I must highlight an ASCII-based
spot of confusion in my post.

Both area and time are in the denominator. I was sloppy in writing the
equation.

energy / (area * time)

Of course the area is still there, and it is an energy flow 'density'.

But hey, what's a few missing units among friends?

73,
Gene
W4Sz

Richard Clark wrote:
On Thu, 02 Dec 2004 14:46:34 -0600, Cecil Moore
wrote:

Gene Fuller wrote:

...energy/area/time.

sounds like joules/sec (power) to me. The IEEE Dictionary agrees.

If so, then a strange dictionary indeed (or strange reader),
Gene's term reduces to energy·time·area^-1 not energy·time^-1

What kind of sound was that anyway?

Richard Clark wrote:
Cecil Moore wrote:

Gene Fuller wrote:
...energy/area/time.

sounds like joules/sec (power) to me. The IEEE Dictionary agrees.

If so, then a strange dictionary indeed (or strange reader),
Gene's term reduces to energy·time·area^-1 not energy·time^-1

I'm surprised that you don't know that energy/(area*time) is the
same as energy/(time*area) which is watts per square meter. The
IEEE Dictionary certainly knows that.
--
73, Cecil http://www.qsl.net/w5dxp

Jim Kelley wrote:
They also point out that the integral of the Poynting vector over an
arbitrary volume which contains no radiator or absorber of energy, or
where no mechanical work is done, is equal to zero. They cite
conservation of energy as the directive.

All that says is: if the flowing energy doesn't change, it hasn't
been dissipated or radiated. The energy is in the process of being
losslessly transferred from one place to another with joules/sec
passing an infinite number of points in space. From _Optics_,
by Hecht: "The energy streaming through space in the form of an
electromagnetic wave, is shared equally between the constituent
electric and magnetic fields. ... We now make the reasonable
assumption (for isotropic media) that the energy flows in the
direction of the propagation of the wave."
--
73, Cecil http://www.qsl.net/w5dxp

On Thu, 02 Dec 2004 18:10:14 -0600, Cecil Moore
wrote:
sounds like joules/sec (power) to me.
energy/(area*time) is the same as energy/(time*area) which is watts per square meter.
Which still leaves you high and shy of area^-1

What was that sound?

On Thu, 02 Dec 2004 14:28:26 -0800, Jim Kelley
wrote:
Born and Wolf does observe that the Poynting vector is adequately
defined as the "density of the energy flow", "the amount of energy which
crosses a boundary surface per second a unit area normal to the
directions of E and H."

Hi Jim,

You were desirous of "value added" writing, I believe. The
explanation and Gene's observation that this vector is not about power
has more correlatives in radiation, of the observable kind. We may as
well tread into the optics side of the family as long as we are here.

The same area bounded expression for light is Lux whose definition is
Lumens (power or energy/second) per square Meter (area).

Lumens are printed (mandate of law) on every box of light bulbs.

[Daggers fly here]
Unfortunately our resident Optical (sic) wizard here, has never been
able to express ANY answer for his Optical pronouncements in ANY
Optical term, not even Lumens. Bringing such topics as Optics to the
discussion and leaving them adrift demands sneers in response to such
babbling sophistries.

73's
Richard Clark, KB7QHC

On Thu, 02 Dec 2004 23:08:00 GMT, Gene Fuller
wrote:
But hey, what's a few missing units among friends?

Hi Gene,

Well, I knew that, and it didn't matter to me. The point of response
was not to correct the mistake of transcription (a lesser
transgression), but to correct the mistake of confirmation (a sin)
which is one of those things that can cascade into attributions
supporting faulty Initial Conditions.

73's
Richard Clark, KB7QHC

Jim Kelley wrote:

I think the source of part of the confusion here is that some people
apparently interpret the 'forward power' reading on their meter to mean
the power into their transmission line.

It's not.

The power input to the transmission line is the instantaneous power,
V(t) * I(t), averaged over one cycle. This is the value indicated by a
classic AC wattmeter used in the power industry. The Bird wattmeter
indicates a so called 'forward' and 'reverse' power, neither of which
are truly power, and have been discussed ad infinitum in this newsgroup.
The difference between the 'forward' and 'reverse' reading on the Bird
wattmeter is equal to the power entering the transmission line.

bart
wb6hqk

Bart Rowlett wrote:
The difference between the 'forward' and 'reverse' reading on the Bird
wattmeter is equal to the power entering the transmission line.

It can easily be proven that the energy in the forward wave that
has not yet been reflected plus the reflected energy is still in
the transmission line. It can be proven, using TV ghosting, that
the reflected energy has made a round trip to the load and back.

It sure would alleviate the confusion if everyone would say,
"... is equal to the net power entering the transmission line."

re dB:

If one is measuring the losses in a 1/4WL stub with the following
configuration using a signal generator equipped with an ideal
circulator and circulator load resistor (SGCL):

SGCL----1/4WL stub-----

What are the losses in the stub in dB? :-)
--
73, Cecil http://www.qsl.net/w5dxp

On Thu, 02 Dec 2004 09:47:54 -0600, Cecil Moore
wrote:


Consider an earlier example made up of lossless lines:

100W XMTR---50 ohm---+---one second long 291.5 ohm---50 ohm load

The voltage reflection coefficient at the load is 0.707. The power
reflection at the load is 0.5, i.e. half the power is reflected.

After steady-state has been reached, the XMTR has output 300 more
joules than the load has accepted. A smaller real-world experiment
will easily verify that it is a fact that all energy sourced that
has not reached the load must necessarily be confined to circulating
energy or losses in the transmission line.

Question: In the above example, where are those 300 joules of energy
located and what is happening to them?

We know that 300 joules is wave energy and RF waves always move
at the speed of light, i.e. they cannot stand still. So please
determine how much energy is moving and in which of only two
possible directions.

Dear Cecil,

Here's my guesses -
The 300 joules of energy decays at a particular rate - i.e., in a
certain interval of time, 63.2% of it will have been converted to and
become dissipated as heat. During that same time interval,Ti, there
will be an equal amount of energy introduced to replenish the amount
lost. In other words, there will be a continuum of energy transferring
into the transmission line to exactly make up for that lost in any
given period of time.

Eventually, someone will disconnect the source generator at time T2.
However, the load will continue to receive energy for a length of
time, Ti, at which point roughly 63.2% of 300 joules of energy will
have been dissipated in the load. If we wait long enough, 99.9% of the
300 joules will have been dissipated, but it will take forever for the
last little bit to disappear.

It kind of makes you think in terms of "life everlasting", doesn't it?

73,

Bob, W9DMK, Dahlgren, VA
http://www.qsl.net/w9dmk

Richard Clark wrote:

On Thu, 02 Dec 2004 14:28:26 -0800, Jim Kelley
wrote:

Born and Wolf does observe that the Poynting vector is adequately
defined as the "density of the energy flow", "the amount of energy which
crosses a boundary surface per second a unit area normal to the
directions of E and H."


Hi Jim,

You were desirous of "value added" writing, I believe. The
explanation and Gene's observation that this vector is not about power
has more correlatives in radiation, of the observable kind.

It's accurate to say that power is something which itself doesn't
propagate in any fashion, at any wavelength.

[Daggers fly here]
Unfortunately our resident Optical (sic) wizard here, has never been
able to express ANY answer for his Optical pronouncements in ANY
Optical term, not even Lumens. Bringing such topics as Optics to the
discussion and leaving them adrift demands sneers in response to such
babbling sophistries.

When Maxwell wanted to draw such distinctions, he included a frequency
dependent term - but allowed the same units throughout.

73, Jim AC6XG

73's
Richard Clark, KB7QHC