Why must engineere resort to quoting from their worshipped Guru's who are
hardly more likely to be correct than they are themslves.

That's easy, because most of the time we have no other choice. When designing
circuits, antennas, troubleshooting, or talking to newsgroups, we have to rely
on other's research. There is no way we can experimentally verify all the data
sheets. charts, graphs, computer programs ect. that are available.
Quoting the last 100 years of antenna research, from worshipped Guru's should
not be a bad thing, because most of us will never have the opportunity to prove
them incorrect. I assume many of the Guru's did the research.
Reg, I am sure you have found numerous errors in Guru's texts, and have tried
to point them out to us. But you cant't just go out in the back yard and burn
all those books:-) Who would we then quote?
73 Gary N4AST

Richard Harrison wrote:
Negative resistance is a gain instead of a loss.

Therefore, doesn't an amplifier have negative resistance?
--
73, Cecil

==========================

Cecil, for once, you are not far from the truth. The problem lies in
producing the equivalent circuit diagram.
----
Reg.

"Reg Edwards" wrote in message
...
Richard Harrison wrote:
Negative resistance is a gain instead of a loss.

Therefore, doesn't an amplifier have negative resistance?
--
73, Cecil

==========================

Cecil, for once, you are not far from the truth. The problem lies in
producing the equivalent circuit diagram.
----
Reg.


Hey guys,
Jog my memory; but don't some power tubes have a high value negative plate
resistance under some bias conditions and will oscillate under no load
conditions if external losses are low.
The 4CX250 family comes to mind.

Tam/WB2TT

SWCAD from Linear. I also built up a model of an ideal SWR meter.

Tam

"Cecil Moore" wrote in message
...
Tam/WB2TT wrote:
There is no current in the steady state.

There is no *net* current in the steady state at the input of a
shorted 1/4WL stub. What do you think the current at the short
is? How did that large amount of current get there without flowing?
--
73, Cecil http://www.qsl.net/w5dxp


Cecil,
I think it is more instructive to turn on a DC voltage at t=0, rather than a
sine wave. In either case, the voltage builds up step wise, with smaller and
smaller steps until you don't see them.

Tam

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On Wed, 26 May 2004 21:56:04 +0000 (UTC), "Reg Edwards"
wrote:

If nobody knows what the internal impedance of a transmitter
actually is, how do you know it's not conjugate matched? :-)
--------------------------------

Because nobody knows. And it wouldn't make slightest difference to anything
if anyone did.

Lord Kelvinator is mighty proud of you, bucko.

And nobody knows why I keep answering your questions either. ;o)

You didn't answer any question, you responded - big difference.

We at least get the varietal name of the grape you are knocking back.

73's
Richard Clark, KB7QHC

"Richard Clark" wrote in message
...
On Tue, 25 May 2004 07:27:03 -0500, "Richard Fry"
wrote:
REALITY CHECK: If tx source Z really was 50 ohms, a tx connected to a 50
ohm load would lose 1/2 of the RF power it generates to that internal Z.

Dear Richard,

This is the time-honored misreading and misapplication of Thevenin's
theorem posed by Edison to confound investors in Westinghouse's AC
generation plants. Look at the ratio of DC to AC power plants
constructed in the past century to find the poor accuracy of your
reading.

73's
Richard Clark, KB7QHC
Richard,
I believe Edison was talking about the Synchronous Impedance of an
alternator. That measurement is based on the short circuit current of the
machine, and limited by the leakage inductance; purposely made large for
self protection. As for pertinent numbers, a 2300V 1000A alternator has an
effective series resistance of about .05 Ohm. That is feeding a load of 2.3
Ohms.

Tam/WB2TT

There is no way we can experimentally verify all the data
sheets. charts, graphs, computer programs ect. that are available.

======================================

There's no need to. Inevitably, 99.9 percent of data to be found in books
does not match up to the exact problem in hand. And what is in hand is VERY
exact. Very early in one's career one realises this and soon discovers it is
largely a waste of time 'researching' the literature for details. There's
too much of it. It is more expeditious to have confidence in one's ability,
to go back to first principles and THEN concentrate on the details in
and - which are NEVER to be found in the books.

The best engineers don't have time to write books - except perhaps for
short, simple ones which educate by concentrating on first principles. A
relatively few number of such books or papers are needed. Nearly all of
them have already been written. Such as Shannon's beautifully concise paper
on Ball-packing.

=====================================

Quoting the last 100 years of antenna research, from worshipped Guru's
should
not be a bad thing, because most of us will never have the opportunity to
prove
them incorrect.

====================================

But good engineers accidentally find them incorrect all the time. It forms
part of their normal wasted time. Anybody who worships a book has only ever
read it (e.g. not built the circuit ) - he has never used it in anger. It
has to be admitted that finding more than two errors in a book (not counting
obvious printing errors) is enough to destroy its sacred properties.

====================================

Reg, I am sure you have found numerous errors in Guru's texts, and have
tried
to point them out to us. But you cant't just go out in the back yard and
burn
all those books:-) Who would we then quote?

====================================

I once quoted (second hand) from a text book on this newsgroup. But it was
in an ironical context. Probably nobody noticed.

I possess remarkably few books on radio enginering. One of then is a
treasured 1937 copy of Terman's Radio Engineering. I may refer to it once
every few years because of its comprehensiveness. I have a poor memory. But
I wouldn't dream of using numbers from it in anger without checking from
first principles they are in the right ball park. I remember first
principles. They are so simple and can be expressed in plain English.

But I could not bear to see books of any sort burned! Carry on quoting
Kraus who I am a little familiar with via this newsgroup.

The bottle is finished. Good Night.
----
Reg, G4FGQ

Jim Kelley wrote:

Cecil Moore wrote:
So the answer is yes, credit cards are a form of money. Sorry.

A distinction is commonly drawn between plastic and cash, Cecil. I
expected you wouldn't be too stubborn to acknowledge that. My mistake.

Do you happen to have a special dictionary where words don't
mean what words mean? Money can be plastic or cash or gold or
silver or worthless coins or sea shells or virtually any other
medium of exchange.
--
73, Cecil http://www.qsl.net/w5dxp



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Tam/WB2TT wrote:

"Cecil Moore" wrote:
There is no *net* current in the steady state at the input of a
shorted 1/4WL stub. What do you think the current at the short
is? How did that large amount of current get there without flowing?
--
I think it is more instructive to turn on a DC voltage at t=0, rather than a
sine wave. In either case, the voltage builds up step wise, with smaller and
smaller steps until you don't see them.

DC doesn't tell us anything about a 1/4WL shorted stub which is a
network problem, not a circuit problem. The net current at the mouth
of the stub is close to zero while the voltage is at a maximum. At
the short at the other end of the stub, transmission line theory holds.
The voltage is close to zero while the current is at a maximum. Now
exactly how can maximum current be flowing through that short if
no current is flowing into and out of the stub. Hint: it can't!

The forward current and reflected current cancel at the mouth of
the shorted 1/4WL stub. However, they add in-phase 1/4WL away at
the short, maybe to many amps of RF current at the shorted end.
Since there is no physical impedance at the mouth of a stub, nothing
except superposition of forward and reflected waves happens there
and nothing except a virtual impedance exists there. All of the action
is at the shorted end of the stub where there exists 100% reflection.
--
73, Cecil http://www.qsl.net/w5dxp



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"Cecil Moore" wrote in message
...
The forward current and reflected current cancel at the mouth of
the shorted 1/4WL stub. However, they add in-phase 1/4WL away at
the short, maybe to many amps of RF current at the shorted end.
Since there is no physical impedance at the mouth of a stub, nothing
except superposition of forward and reflected waves happens there
and nothing except a virtual impedance exists there. All of the action
is at the shorted end of the stub where there exists 100% reflection.
--
73, Cecil http://www.qsl.net/w5dxp

I just did the simulation again, and you are right. For a 1V signal feeding
a 50 Ohm line through a 450 Ohm series resistor, there is 20 ma of
current flowing through the short. Don't understand why I didn't see it the
other time. There is 0 current through the 450 Ohm
resistor.

Tam/WB2TT

If rattle-snake meat is fit for human consumption I assume you don't pepper
it with rat shot. Probably best washed down with a delicate dry white.
----
Reg.

"Tam/WB2TT" wrote in message
...
There is no current in the steady state. The steady state voltage is
independent of source impedance, which affect only how long it takes to
reach that. I ran a simulation on this, and you can see that as the
voltage
builds up, the current decreases

Tam


Whoops, ERROR. There is no current flowing from the source, but there is
current flowing through the short in steady state.

Tam

For Gawd sake, don't tell Cecil he's right. There'll be no stopping him!

"Reg Edwards" wrote in message
...
If rattle-snake meat is fit for human consumption I assume you don't
pepper
it with rat shot. Probably best washed down with a delicate dry white.
----
Reg.


Tastes just like chicken.
It was a head shot. No spoiled meat. I have JPEGs.
I gave the tail to one of my grad students.
Riesling or Pinot Noir?
H.

Tam/WB2TT wrote:
"Cecil Moore" wrote:

The forward current and reflected current cancel at the mouth of
the shorted 1/4WL stub. However, they add in-phase 1/4WL away at
the short, maybe to many amps of RF current at the shorted end.
Since there is no physical impedance at the mouth of a stub, nothing
except superposition of forward and reflected waves happens there
and nothing except a virtual impedance exists there. All of the action
is at the shorted end of the stub where there exists 100% reflection.

I just did the simulation again, and you are right. For a 1V signal feeding
a 50 Ohm line through a 450 Ohm series resistor, there is 20 ma of
current flowing through the short. Don't understand why I didn't see it the
other time. There is 0 current through the 450 Ohm resistor.

Install a Bird wattmeter at the 450 ohm resistor and you will read
forward power and reflected power. The *net* current through the 450
ohm resistor is zero. The forward current is not zero. The reflected
current is not zero. Their magnitudes (10 ma?) are equal and their phases
are 180 degrees from each other so they cancel to net zero current.

If we take the forward current at the 450 ohm resistor as a reference of
10 ma at zero degrees, the reflected current will be 10 ma at 180 degrees.
Those two current signals add up (superpose) to zero at the resistor.
--
73, Cecil http://www.qsl.net/w5dxp



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Tam/WB2TT wrote:
Whoops, ERROR. There is no current flowing from the source, but there is
current flowing through the short in steady state.

There is no net current flowing from the source, but there is net
current flowing through the short during steady-state. Where does that
current come from? It comes from the in-phase addition of forward
and reflected current. The voltage goes to zero and the current doubles
at a short. The zero net current from the source comes from the out-of-
phase addition (subtraction) of forward and reflected current.

This is where that darned definition comes into play. By definition,
the reflected current is being 100% re-reflected and the source is
delivering zero current or, in a system with losses, is delivering
only the amount of current needed to offset the losses.

We can argue whether the reflected current makes it back into the
source or not. But there is no argument that reflected current is
originating at the short in the 1/4WL stub because it can be
easily measured. Forward current and reflected current are very
close to equal magnitudes all up and down an efficient stub.
--
73, Cecil http://www.qsl.net/w5dxp




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Cecil, W5DXP wrote:
"The forward ciurrent and reflected current cancel at the mouth of the
shorted 1/4 WL stub. However, they add in-phase 1/4-WL away at the
short, maybe to many amps of RF current at the shorted end. Since----."

Very clear and concise. I am persuaded that once circulating current is
established, only the current required to supply losses is drawn at the
mouth of the shorted 1/4-WL stub.

Best regards, Richard Harrison, KB5WZI

Reg Edwards wrote:
For Gawd sake, don't tell Cecil he's right.

You wouldn't expect a Texan to be left, would you, Reg?



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Steve Nosko wrote:

"Richard Clark" wrote:

wrote:
Well Richard, here's your chance. Please enlighten us on J.C.
Slater's words in _Microwave_Transmission_.

What was the original question? [accredited stock response]

It's clear that R.C. loves tweeking Cecil.

Trouble is, I usually have no idea what his random ramblings
are all about.
--
73, Cecil http://www.qsl.net/w5dxp



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Steve Nosko wrote:
From this I infer that Cecil believes that once the transient portion of
the response has concluded you are in the steady state and no more
reflections are occurring. Is this a correct re-statement of your belief,

No, no, no. That is a re-statement of the other side of the argument
from mine. I often use devil's-advocate type arguments.

The definition of steady-state by the other side is pure unvarying
sine waves with no noise and no modulation. Then the reflections
sorta disappear into a steady-state mush of standing waves. A
modulated TV signal, according to their argument, is not a steady-
state signal. Within this steady-state mush of standing waves, energy
never makes it from the load back to the match point. Apparently,
because of the uncertainty principle, reflected energy doesn't
actually exist anywhere until it is radiated or dissipated, i.e.
its probability wave collapses.

I have challenged them to produce a standing wave without a rearward-
traveling wave but nobody has been up to that challenge.
--
73, Cecil http://www.qsl.net/w5dxp




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"Steve Nosko" wrote in message
...

"Tam/WB2TT" wrote in message
...

"Henry Kolesnik" wrote in message
.. .
Richard
...I got
out the book REFLECTIONS II by Walt Maxwell W2DU. I'm typing
verbatim
from
page 2-2 and 23-1

I paraphrase / quote the quote:
Power reflected from a mismatch back into the PA is not absorbed
there.
He writes:
"when the pi-network tank is tuned to resonance, a virtual
short circuit to rearward traveling waves is created at the input
of the network. Consequently, instead of the reflected power
reaching the tubes of the amplifier, it is totally re-reflected
toward the load by the virtual short "

Hank, I'm sorry, but I believe this is not correct as stated. The
word
"totally", I believe is misleading and contrary to what I think all will
agree. Namely that there MUST be SOME real part (although the true amount
is disputed here) to the Zout of the PA and therefore SOME power MUST be
absorbed there. I believe the point of contention truely is just how much
is absorbed and how much is reflected...

...Also what happens in a transistor final with no pi?

AGAIN. Be careful that you DO NOT keep assuming that the full power is
the
incident power. Incident meaning forward power or that which the
transmitter is sending toward the load. I have a real corker below. Be
careful. Do not try this at home, I am a professional. (yea, I know
this'll
spawn all kinds of grief)


Tam sez:
Henry,
Here is an example of what you just said. Take a sine wave source, and
connect it to a 1/4 wave section of shorted transmission line through a
series resistor R. The reflected wave will reach this resistor 1/2 cycle
later, and will be in phase with the source. For a lossless transmission
line, there will be *0 Volts across the resistor*. There will be 0
current
through the resistor, and the reflected wave will be re reflected for
all
values of R, including R=Z0, because the reflected wave will not "know"
what
R is. You can get the same answer from knowing that the impedance
looking
into a 1/4 wave section of shorted transmission line is infinite.
Tam/WB2TT

Tam,
Although I believe you have digressed somewhat, I will follow this
path
since it contains a closely related concept. You obviously have a pretty
good handle on much of this (as others do, up to a point, and struggle to
make their mental models fit the reality - or to make other's mental
models
fit theirs)...However, there is a paradox here which appears to be the
root
of this disagreement and your example hit it right on the head. You have
some implicit assumptions here.

1) Zero volts across the resistor = (not said, but implied) the t-line
acts
like an open at the input end, therefore there is no current into the line
which results in the zero V across R. V=I^2 * R. I think everybody will
agree with this. (shorted 1/4 wave acts like an open and an open 1/4 wave
looks like a short - mantra of all, no?).

2) Resistor current = zero therefore reverse traveling wave gets reflected
toward the load end. The implication clearly is that with zero resistor
current, no energy can be flowing out that way, so it must be reflected.

HOWEVER...
Been a while since I went to this depth and interesting to do so,
though
unnecessary, I will anyway...

If the input to this stub acts like an open, there can be NO current,
thus no power entering, therefore there can be no forward wave, no
reflected
wave and no summation of waves to make the open in the first place and no
need to re-reflect the reflected wave from the resistor who (or is it
whom)
has no current. This appears to be the root cause of this problem.
Now, we can say that (and I think it has been said) that it makes no
difference how large these two waves (which cancel each other to form the
open circuit at the stub input) can be any absolute magnitude. 1 amp 10
amps 100 amps doesn't matter - they cancel. So what are they really?
There are two things to consider as you work out how you will resolve
this paradox in your mental model.
1) I believe the most important -- If the Z looking in to the stub is
high,
how can you send a large amount of power down the line. If you say it is
an
infinite Z then you have a really big problem explaining how it got there
in
the first place.
2) There is a tendency to assume that the forward power is the same power
as
when the load is not a short, but Zo.

Interesting puzzle, but I don;t need to go further. At some point you
must
'believe' something and I can comfortably stop there...for now.

Oh well...
--
Steve N, K,9;d, c. i My email has no u's.


Steve,
I think there is an analogy here to a high Q resonant parallel tuned
circuit. It takes very little to exite this, but there can be large
circulating current in the L and C.

BTW, on my shorted transmission line: I had looked at the current on the
transmission line - at the wrong end of the TL. There is current at the
shorted end, none on the source end in steady state. Didn't even know the
program was smart enough to know the difference. Seems to me that once you
have put all the energy into the TL that it can store, you don't have to
supply any more energy (?)

Tam/WB2TT

Steve Nosko wrote:
I paraphrase / quote the quote:
Power reflected from a mismatch back into the PA is not absorbed there.
He writes:
"when the pi-network tank is tuned to resonance, a virtual
short circuit to rearward traveling waves is created at the input
of the network. Consequently, instead of the reflected power
reaching the tubes of the amplifier, it is totally re-reflected
toward the load by the virtual short "

Hank, I'm sorry, but I believe this is not correct as stated. The word
"totally", I believe is misleading and contrary to what I think all will
agree. Namely that there MUST be SOME real part (although the true amount
is disputed here) to the Zout of the PA and therefore SOME power MUST be
absorbed there. I believe the point of contention truely is just how much
is absorbed and how much is reflected...

Steve, what you are missing is that the match point is not at the transmitter
terminals and reflections indeed do flow into the transmitter terminals. The
match point is between the tube finals and the input to the pi-net tuning
section. There are zero reflections between the input of the pi-net tuning
section and the tube finals. This is what Walter Maxwell was saying. The
"input of the network" that he is talking about is the wire between the
tube finals and the built-in pi-net tuning section and, indeed in a properly
tuned transmitter, there will be no reflections at that point which was
commonly known as a "Zg-match point".

All of Walt's writings assumed a Zg-match internal in the tube transmitter
at which all reflections were canceled. We hashed that out about 20 years
ago. That's when I first communicated with Walt through snailmail.
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil Moore wrote:

Steve Nosko wrote:
From this I infer that Cecil believes that once the transient portion of
the response has concluded you are in the steady state and no more
reflections are occurring. Is this a correct re-statement of your belief,

No, no, no. That is a re-statement of the other side of the argument
from mine.

Perhaps he thought you believed that because you're the only one who has
said it?

73, Jim AC6XG

Tam/WB2TT wrote:

SWCAD from Linear. I also built up a model of an ideal SWR meter.

Tam

I almost bought LLTC when they came out with that. Should have. Thanks
Tam.

jk

Tam/WB2TT wrote:
Seems to me that once you
have put all the energy into the TL that it can store, you don't have to
supply any more energy (?)

Tam/WB2TT

BINGO!! No more _energy_ flows - until or unless something changes.
(TV signals are of course always changing.)

73, Jim AC6XG

Jim Kelley wrote:

Cecil Moore wrote:

Steve Nosko wrote:
From this I infer that Cecil believes that once the transient portion of
the response has concluded you are in the steady state and no more
reflections are occurring. Is this a correct re-statement of your belief,

No, no, no. That is a re-statement of the other side of the argument
from mine.

Perhaps he thought you believed that because you're the only one who has
said it?

It's a very condensed verion of the reams of stuff that some posters have
posted over the past year. In particular, when I tried to introduce noise
and modulation to prove my point, I was told that noise and modulation are
not allowed during steady-state.
--
73, Cecil http://www.qsl.net/w5dxp

On Wed, 26 May 2004 11:44:00 -0500, "Steve Nosko"
wrote:

I think "superposition" is ther wrong term for this. If I could spell
reciprocity, I'd say that it is a better word.
Digression, though minor: Superposition refers typically, to the
application of two signals to a circuit and the resulting response being the
sum of the individual responses. no?

No/Yes. The "two" signals are those I described, the one from the
source as source and the one from load as source. This is the
convention of Circuit Analysis by Mesh or Nodes. Kirchhoff mandates
all voltages will sum to zero. The summing is a solution of
simultaneous equations - Superposition.

Now some meat I'd like to pursue...

...a 500 Ohm Source...you will never launch much power into a 50 Ohm
system because it would immediately hit a reflective interface at the
antenna connector.

There's a question I see here as to wheather the power was "launched" in
the first place and this may be part of the assumption (or set thereof)
which (my gut feel says) leads the logic astray.

It was an aside (a stage whisper).

This means that a 500 Ohm source, when confronted
by power going towards it from a 50 Ohm system will reflect most of
that power (but how did we get this power into the system in the first
place - Karma?) This, by design, will never happen in any transistor
ham rig built in the last quarter century.

I think this is true...BUT let's ask this same question of a 5.0 ohm
source?? How would you carry this through Richard C? I submit that THIS
source CAN launch significant power down the line.

And here we come to issues of initial conditions and their variation
to force a conclusion. Namely, the unstated condition is how much
voltage is available? SWR is the diagnosis, and absorption of power
is the issue. Launching of power also suffers from the same
condition, but it would be well enough to examine the reflection
first. Launching problems is a sidebar.

The answer is the transmitter source Z is 50 Ohms at rated power.

OK, so now I see you are of the "Zs=50 ohms" camp.

I have measured such things professionally and certified such facts as
accurate with a chain of references back to the National Bureau of
Standards. Such is my camp.

If a watt of power is chooglin' down the line toward it, that 50 Ohms is
going to dissipate into a watt worth of calories. This can be argued
with wave mechanics, or lumped circuit equivalents - doesn't matter
because it's all the same calories.

All ok with me _IF_ Zs=50. I'm not convinced however. I have to think
more about the modern broad-band transistor PA to have an strongly arguable
opinion on this concept.

It is a convention of design that is covered in many design texts.
Academe takes this (Zs=50) for granted so much so that it is rarely
discussed. Even here I have references (Academic) that make this
point explicit and I have offered them here in debate.

what do we need tuners for?

I think the answer here is that if the transmitter can take the strange
impedance it sees, then it isn't needed. Like Hanks 30L1 that, however,
couldn't take it very well.

However, this is not an answer to the question.

Furthermore, there is an implicit assumption here in your reasoning
which I believe is key and leading to some error. There is an unspoken
assumption that the power which makes it to the antenna after all the "
round-and-round until the antenna finally radiates it" is the FULL output
and I believe it AIN'T.

As I have never stated this, you have to answer for the conflict that
follows.

It is that little dribble that made it into the
line in the first place. a.k.a. the Tx is not generating the full output.
I think this assumption is causing much trouble.

This begs the question: What is the full output? A battery sitting on
the shelf is not generating its full output is a simple example, but
does not tell us what that full output may be. This is the problem of
definition by negatives.

It is not generating:
1W
nor
10V
nor
100°C
nor
1 H.P.

Was it ever capable of those generations in the first place? Under
what conditions? Saying what is "not" has no useful information here.

If we are discussing what happens to power impinging upon the source,
it should be obvious that if that power is OUT OF PHASE trouble
follows in the form of currents. If that power is IN PHASE trouble
follows in the form of potentials. Trouble is proportional to the
degree of mismatch. Trouble arrives through the model of waves,
trouble resides in the model of lumped equivalent circuits. It is the
same trouble either way in the form of heat. Choose your poison
because equipment manufacturers have built-in foldback mechanisms and
advise you to use a tuner for good reason.

Unless, of course, I have been smoking the wrong brand.

It will be available over the counter in British Columbia soon.

73's
Richard Clark, KB7QHC

Jim Kelley wrote:

Tam/WB2TT wrote:
Seems to me that once you
have put all the energy into the TL that it can store, you don't have to
supply any more energy (?)

BINGO!! No more _energy_ flows - until or unless something changes.
(TV signals are of course always changing.)

You can prove your point only by demonstrating an RF storage
battery in which RF energy stands still.

Got news for you, Jim. RF energy *always* flows because it *cannot*
stand still. It flows in one direction in a transmission line, at the
speed of light, until it encounters a physical impedance discontinuity
at which point reflections occur and some or all of the energy changes
directions, but always moving at the speed of light. ExH is the power.

Of course, you are talking about *NET* energy above. Forward
and reflected energy continue to flow unabated. RF component
energy has no choice except to flow at the speed of light. If
there doesn't exist a match point to turn the reflected energy
around, it *will* flow into the source. That you subtract the
reflected energy from the forward energy at the source output
to obtain the "generated energy", is just a math shortcut and
bears no resemblance to reality. It is a definition created by
man for the purpose of avoiding a very complicated problem.

It is akin to the problem of absolute motion in space-time.

It follows that when you have the same bank balance at the beginning
of the month and the end of the month, you tell everyone that you
had no debits or credits during that month. Again, you forgot to use
the word "NET".
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:

[snip]

The definition of steady-state by the other side is pure unvarying
sine waves with no noise and no modulation.

[snip]

I have challenged them to produce a standing wave without a rearward-
traveling wave but nobody has been up to that challenge.

73, Cecil http://www.qsl.net/w5dxp

Cecil,

I don't plan to enter this endless argument about transmission lines,
but there are a couple of points you might want to consider.

* Steady state simply means that a phenomenon has no inherent reference
to its time of origin. One cannot observe a steady-state wave and
determine any clue about when it started. It contains no absolute time
markers. A transient, on the other hand, contains direct reference
information about when it was formed. There is no requirement that the
steady state phenomenon is a simple sine wave.

Many problems in math, science, and engineering exhibit both transient
and steady state solutions. It is not clear why there is any confusion
at all in this thread.

* Standing waves don't require the pre-existence of traveling waves. A
straightforward application of Maxwell's equations with appropriate
boundary conditions for the physical environment will lead to standing
waves directly. Check out one of your recently quoted favorite authors,
J. C. Slater, and look at some of the resonant cavity stuff. Most
definitely standing waves, but you will find lots of complex Bessel
functions and darn few traveling waves.

In virtually every transmission line situation proposed on RRAA, whether
tuned antenna feed lines or quarter-wave stubs, the transmission line is
resonant. It is possible to consider the resulting standing waves as the
sum of two traveling waves, but it is equally valid to consider the
transmission line as a simple resonator. The physically measurable
instantaneous voltages and currents are precisely the same whether one
considers oscillation from capacitive to inductive energy storage in the
line or the sum of two counter-traveling waves.

You often refer to wave-particle duality and to the use of S-parameters
instead of lumped circuit analysis. The world of science and engineering
is absolutely filled with this sort of dual description for physical
phenomena. In many cases one approach will be more convenient or more
intuitive, but that does not make the dual approach less valid.

There's more than one way to skin a cat.

73,
Gene
W4SZ

On Wed, 26 May 2004 10:34:57 -0500, "Steve Nosko"
wrote:
Hey! I know it HAD to be a PREGNANT Chicken that came first...


Well actually....

One explanation I've read (Scientific American, I think) offered that
some folks believe that chickens have eggs to get more chickens.
Wrong. Eggs have chickens to get more eggs.

Another superposition issue. ;-)

73's
Richard Clark, KB7QHC

On Thu, 27 May 2004 10:49:25 -0500, Cecil Moore
wrote:
It's clear that R.C. loves tweeking Cecil.

Trouble is, I usually have no idea what his random ramblings
are all about.

Steve, perhaps you should repeat your observation with easier words.

Cecil Moore wrote:

Jim Kelley wrote:

Tam/WB2TT wrote:
Seems to me that once you
have put all the energy into the TL that it can store, you don't have to
supply any more energy (?)

BINGO!! No more _energy_ flows - until or unless something changes.
(TV signals are of course always changing.)

Of course, you are talking about *NET* energy above.

Right. There isn't another kind.

73, Jim AC6XG

Cecil Moore wrote:
It's a very condensed verion of the reams of stuff that some posters have
posted over the past year. In particular, when I tried to introduce noise
and modulation to prove my point, I was told that noise and modulation are
not allowed during steady-state.

Stands to reason. Intentionally absent from the steady state are noise,
modulation, transients, and any other perturbation. It would be kinda
like opening the lid of an adiabatic chamber in order to see if the
internal temperature stays constant.

73, Jim AC6XG

Gene Fuller wrote:
* Standing waves don't require the pre-existence of traveling waves.

Please present an example of a standing wave that exists without
a forward-traveling wave component superposed with a rearward-
traveling wave component.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:

Jim Kelley wrote:

Cecil Moore wrote:
Of course, you are talking about *NET* energy above.

Right. There isn't another kind.

That goofy assertion doesn't even merit a response.



Following your logic, two people shooting at each
other with identical bullets can do no harm because
the net energy is zero. Care to prove your theory?

How many sources ya got in that example, Cecil? Is that the same to
you? If it is, then I can see why you don't understand.

73, Jim AC6XG
73, Cecil http://www.qsl.net/w5dxp

Jim Kelley wrote:

Cecil Moore wrote:
Of course, you are talking about *NET* energy above.

Right. There isn't another kind.

That goofy assertion doesn't even merit a response.

Following your logic, two people shooting at each
other with identical bullets can do no harm because
the net energy is zero. Care to prove your theory?
--
73, Cecil http://www.qsl.net/w5dxp

Jim Kelley wrote:

Cecil Moore wrote:
It's a very condensed verion of the reams of stuff that some posters have
posted over the past year. In particular, when I tried to introduce noise
and modulation to prove my point, I was told that noise and modulation are
not allowed during steady-state.

Stands to reason.

By no stretch of the imagination, can that be dubbed "reason".

"Steve Nosko" wrote in message ...
OH! NO! Vortex vs. Bernoulli

Actually, it's Circulation vs. Newtonian vs. Bernoulli -- all three
are different mathmatical means of describing accurately and precisely
what happens when a airfoil produces lift. Actually each is simply a
different way of expressing exactly the same thing, but none of them
translates well to a real-life understanding of the concept. One of
the problems is that causes and effects get confused and
oversimplified by the math.

Much the same with reflections, transmission lines, and impedance
matching. While reflections do indeed exist on transmission lines when
mismatched to a source or load, they simply create standing waves.
Standing waves create non-optimum impedances depending on the
characteristics and length of the line. These impedances interact with
source and load impedances in very predictable and calculated ways.
Efficiency of power transfer is then determined by optimizing the
matching of these impedances. Optimimizing impedances then eliminates
reflections --- a circle of causes and effects.

Mathmatically, it's more expedient to skip much of the in-between
cause-and-effect stuff, and jump directly to describing the entire
process as a direct relationship between reflections and power
transfer -- which causes problems when attempting to visualize or
explain the process -- because that's not the way it really works.
It's not quite that simple and direct.

A standard SWR meter is a good example. It can't conveniently measure
reflections OR standing waves, so it measures mismatch. Since
everything is directly related, it could be said that it measures
reflections -- but it really doesn't. So, it doesn't really matter
unless you try to understand how the meter works in terms of how it
measures reflections or standing waves.

Al

Cecil Moore wrote:
Gene Fuller wrote:

* Standing waves don't require the pre-existence of traveling waves.


Please present an example of a standing wave that exists without
a forward-traveling wave component superposed with a rearward-
traveling wave component.
--
73, Cecil http://www.qsl.net/w5dxp



Cecil,

Sorry, you are not paying attention.

I gave you a reference that is full of such examples. Another reference
you have quoted on numerous occasions is "Transmission Lines and
Networks" by Walter Johnson. Take a look on page 164. He gives a
description of standing waves and then comments, "One can imagine two
oppositely traveling waves, . . . "

Note that he uses "imagine", not required, essential, or any other
mandatory word.

I do not claim the use of superposed traveling waves is wrong. However,
it is merely a mathematical trick, not unlike describing a square wave
as a summation of Fourier components. This is very commonly done, and it
is often very useful. It does not mean that mathematically derived
sub-components are somehow more valid representations of nature than the
original form.

73,
Gene
W4SZ