Cecil Moore wrote:

wrote:
I have often suspected that it is the existence and use of 'Bird watt'
meters that has convinced so many of the existence of forward and
reverse power; a belief which many seem absolutely unwilling to
relax their hold on despite the difficulties it causes them.

OTOH, a TDR causes you difficulties. And just how do you explain
standing waves without a forward wave and a reflected wave?

Can you expand on why you think a TDR causes me difficulties?
I can't think of any reasons.

As for standing waves, I have no difficulties with forward
and reflected voltage waves. They work perfectly fine.

....Keith

Cecil Moore wrote:

wrote:
Of course if you let go of Pfwd and Pref and just used Vfwd and Vref
you would quickly learn that you had no interest in Pfwd and Pref
and thus your inability to determine them would not cause you
much distress.

Uh Keith, radiated *POWER* is what we are trying to get from our
antennas.

Yes indeed. Net power. The only power that counts.
Pnet = average( v(t) * i(t) )

Forget that forward and reverse stuff. That's not what is radiated.

....Keith

Roy Lewallen wrote:
I've done my analysis, and am satisfied with it. That's why I don't
rearrange things to suit your view of reality.

I've never before seen a person so proud of a contradiction. If reflected
power is greater than forward power, then the Poynting vector points away
from the load, but you have said it doesn't. So which is it?

Why are you unable to calculate the correct terms, collect them, or
whatever you think necessary, and show us what values they are and how
they add up to give us the forward and reverse powers you hypothesize?

I don't choose to waste my time on such a no-brainer issue. If the Poynting
vector points toward the load, the reflected power cannot be greater than
the forward power. Chipman goes out of his way to indicate that such an
apparent contradiction is caused by a resonance effect. The opposite sign
of the reactance of Z0 Vs the load is re-reflecting energy back to the load
because the load resistance is in series with the inductive reactance of the
load and the capacitive reactance of the feedline. The re-reflected energy
supplied by the capacitive reactance becomes forward power in the resistance.
That's why the Poynting vector points toward the load. According to Chipman,
that's why forward power minus reflected power CANNOT be negative.
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

wrote:
Can you expand on why you think a TDR causes me difficulties?
I can't think of any reasons.

There's more than just voltage in those returned pulses.

As for standing waves, I have no difficulties with forward
and reflected voltage waves. They work perfectly fine.

That takes care of the E-field. But do you think a wave can exist
without an H-field? If not, the wave possesses energy, by definition.
Energy flowing past a point is power.

Your voltage-only waves violate the conservation of energy
principle and the accepted laws of physics for EM waves.
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

wrote:
Forget that forward and reverse stuff. That's not what is radiated.

Uh Keith, power delivered to the antenna equals forward power minus
reflected power. I notice you have not provided a way for standing
waves to develop without the existence of reflected waves. Do you
also believe that standing waves don't exist?
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

wrote:
When you use a pulse, p(t) = v(t) * i(t) shows the pulse going
by and coming back too, if it reflects. But for that, you have to
look at things in the time domain, something a number of readers
here refuse to do for continuous sinusoidal excitation. When you
look at continuous sinusoidal excitation in the time domain all
the information you need about power is provided without having
to resort to Pfwd and Prev.

Yes, but those steady-state shortcuts often lead to a distorted
view of reality. Exactly what magic happens at the instant when a
system goes from the transient state to steady-state?
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

"Cecil Moore" wrote in message
...
Yes, but those steady-state shortcuts often lead to a distorted
view of reality. Exactly what magic happens at the instant when a
system goes from the transient state to steady-state?

there is no magic, and real systems can never get to steady state. the
steady state approximations are used by engineers who understand their
limitations and know when they can apply them to easily get answers that are
good enough for every day use. engineers who don't understand them can
always use the full field equations and calculate the exact answers if they
have the time and enough information about the system... but they will never
be able to answer the question about forward and reflected power except at a
specific instant in time and single location in the system as the transients
never go away and power in is never equal to power out except by
coincidence.

On Fri, 19 Sep 2003 07:07:35 -0500, Cecil Moore
wrote:
Your voltage-only waves violate the conservation of energy
principle and the accepted laws of physics for EM waves.

Hi Cecil,

Problems of speed reading again afflict you. Or is it the phenomenon
of copy machine hypnosis, where with each sweep of the light you
acquire more virtual education? That technique works better if you
hold single pages up instead while looking down through sunglasses.
(Not nearly as expensive as tuition by the way ;-)

From Chipman (no point in offer the page # is there?):
"Postulate 4. At the intersection of any transverse
plane with the line conductors there is a unique
value of potential difference between the conductors
at any instant..."

As you reject Postulate 4 explicitly in your statement(s), you also
reject your own arguments couched in Chipman's discussion that you
cut-and-paste into your derivative works.

Next time you ride your bike to the library, take the time to read
Chipman's work instead of copying it. Given the nearly universal
silence in this group to such insights offered above in the quote, it
seems you should be in rather crowded circumstances competing to read
that same volume - none here seem to have time to read nor quote the
obvious.

The kulture of Institutionalized Ignorance festers on.

73's
Richard Clark, KB7QHC

On Fri, 19 Sep 2003 13:58:36 -0000, "David Robbins"
wrote:
"Cecil Moore" wrote in message
...
Exactly what magic happens at the instant when a
system goes from the transient state to steady-state?

there is no magic, and real systems can never get to steady state. the
steady state approximations are used by engineers who understand their
limitations and know when they can apply them to easily get answers that are
good enough for every day use.

Hi David,

This is the difference between Engineering and religion. All
Engineering works with error and simply states the limits of
confidence to known factors. That is 1 Ohm/Volt/Ampere to a tolerance
of 20% or 10% or 5% or better. When differences between known
boundary conditions far exceed the error of their determination, then
you can rest assured that you have a solution that is an accurate
portrayal of those different boundary conditions. (On reflection,
even religion acknowledges error; so comparisons are an affront to
that study as well. What goes on in these "debates" is simple,
narcissistic laziness.)

I offered a simple line loss problem some time ago to which there was
only one correct submission (be e-mail no less). This problem
approached this "debate" with known errors and the correspondent found
a solution to within 0.06 dB while others, frozen in mental gridlock,
failed to even choose the conventional "perfect" answer. In the work
place they would be staring at the bench, transfixed in the agony of
Zeno's paradox, while real techs (not even engineers) would have the
problem whipped before the first break (and still had done productive
work too).

73's
Richard Clark, KB7QHC

Richard Clark wrote:
From Chipman (no point in offer the page # is there?):
"Postulate 4. At the intersection of any transverse
plane with the line conductors there is a unique
value of potential difference between the conductors
at any instant..."

As you reject Postulate 4 explicitly in your statement(s), ...

Richard, you really need to grasp the difference between exclusive
and inclusive statements. Keith implies a voltage-only wave. It
is my understanding that an EM wave cannot exist without an
associated H-field. Chipman doesn't say EM waves can exist
without an H-field. EM waves possess both E-fields and H-fields.
The power associated with an EM wave is E x H. An H-field around
a wire implies a current in that wire. My objection to Keith's
statement is his voltage-only wave existing without current, energy,
or power.
--
73, Cecil, W5DXP

Richard Clark wrote:
It is more than evident that your "objections" are inventions of your
own construction.

Perhaps you missed Keith's assertion that he believes in voltage
waves but not in power waves, thus implying that voltage waves are
not associated with (E x H) power.

You did not respond to your refutation of your own source, ...

Chipman's assertion of voltage doesn't imply that he doesn't believe
in current. He just didn't mention current. Exclusive Vs inclusive -
please learn the difference.
--
73, Cecil, W5DXP

On Fri, 19 Sep 2003 09:58:25 -0700, Cecil Moore
wrote:

Richard Clark wrote:
It is more than evident that your "objections" are inventions of your
own construction.

Perhaps you missed Keith's assertion that he believes in voltage
waves but not in power waves, thus implying that voltage waves are
not associated with (E x H) power.

You did not respond to your refutation of your own source, ...

Chipman's assertion of voltage doesn't imply that he doesn't believe
in current. He just didn't mention current.
He does mention current as Postulate 2 - you simply suffer from speed
reading past that passage.
Exclusive Vs inclusive -
please learn the difference.
Please try reading your references rather than using them as
cut-and-paste crutches to wobbly arguments.


Hi Cecil,

The difference is found by interchanging the names Keith and Chipman
(forgive me both) from these originals:
Keith's assertion that he believes in voltage
waves but not in power waves
and
Chipman's assertion of voltage doesn't imply that he doesn't believe
in current.

finds by your own logic that:
Keith's assertion of voltage doesn't imply that he doesn't believe
in current.
which is consistent with what he has published (not what you have
projected).
and
Chipman's assertion that he believes in voltage
waves but not in power waves
is literally stated in his postulates (of which you are admittedly
wholly ignorant).

Thus Chipman and Keith are not in contradiction, that is a product of
your own invention and your violations of Chipman's postulates.

73's
Richard Clark, KB7QHC

On Fri, 19 Sep 2003 13:15:05 -0700, Cecil Moore
wrote:
Thus, it is an absurd argument that Chipman never made.

Well Cecil,

Given you are eminently untutored in Chipman's greater work, and
choose only those portions that suit your cut-and-paste philosophy; it
comes as no surprise what arguments of invention you might project.

73's
Richard Clark, KB7QHC

Keith wrote:
"---it will turn out that there is no value in forward and reverse power
on a line with non-real Zo."

The Bird wattmeter works well enough on coax lines used between the
usual transmitter and antenna. Loss produces reactance in coax. We don`t
seek lossy coax. If it becomes lossy, the line is likely to be replaced.

If a transmitter isn`t matched when the load is matched to the coax, an
improved match between the transmitter and the coax may come from
mismatching the load.

A true conjugate match exists everywhere in the system between the
transmitter and the antenna. That is, one could check the impedances in
both directions at any place in the system and find that the two
inpedances are conjugates of each other.

There is reactance in every non-resonant length of coax which is not
terminated in its characteristic impedance value.

The vector sum of the incident and reflected wave voltages is less than
the arithmetic sum at a point 1/8 wavelength back from the reflection
point. At 1/8 wavelength back from a reflection, the incident and
reflected wave voltage vectors are 90-degrees apart. At 1/8 wavelength
in coax, the reactance is numerically equal to the Zo of the line, as a
piece of trivia.

At 1/4 wavelebgth back from the reflection, the incident and reflected
wave voltage vectors are 180-degrees apart. The line voltage total is
thus the arithmetic difference of the incident and reflected wave
voltages.

At 1/2 wavelength back from the reflection, the incident and reflected
wave phases have continued their phase changes in opposite directions
with distance back from the reflection until the voltages have reached
the in-phase condition. In a lossless line, the conditions at the
reflection point would be repeated at a point 1/2-wavelength back.

When a resistance load matches the Zo of its feedline, the reflection
coefficient is zero, so there is no reflection from the load. The load
absorbs all the incident wave. The effect of a reactive load is merely
to displace the positions of the minima and maxima along the line but
not with respect to each other.

Best regards, Richard Harrison, KB5WZI

Keith wrote:
"Not to mention the difficulties that arise on lines with complex Zo."

Transmission lines are strict enforcers. They only allow a volts to amps
ratio traveling the line of Zo.

Transmission lines are almost always selected and used for low-loss. The
Zo`s which are real (non-reactive) are not complex. The series
resistance is small as compared with te series inductive reactance. The
shunt conductance and dielectric loss are small as compared with
susceptance.

The square root of L/C is a nearly pure resistance and equals Zo, and
equals the square root of Z/Y. Zo is not complex.

The incident and reflected waves are both forced to have a V/I = Zo. In
the case of the reflected wave, the ratio is often written -Zo to
indicate a travel in the direction of the transmitter instead of toward
the load.

Keith also wrote:
"It is a voltage wave which does the travelling."

Sure. That`s why it is called a TEM wave. The E-field is all alone.

Best regards, Richard Harrison, KB5WZI

Ok, now take the capacitor off, and measure the voltage at the end
of the inductor. What do you get?

Afraid to measure it, eh? Go ahead, we can ignore the 15 pF for now,
as
the load was 100pF. What do you get?

You asked for an open. 15pf is about 1000 ohms at 10 Mhz. This is a long
way
from an open. In any case, I suggest it might be your turn to produce
some
experimental results.

Go ahead and measure it anyways, i'd like to know what you get. If you
think about it, this would be a
clue as to the forward Vi voltage.




Classic Rho gives -1, which is a short, and conjugate Rho gives
+1j, which is ALSO a short.

As I recall, the purpose of rho was to compute the reflected voltage so
that net voltage could be computed using:
Vnet = Vfwd + Vref
Using rho = -1 produces Vref = -Vfwd yielding Vnet = 0 as expected for
a short.
Using rho = +1j produces Vref = +1j * Vfwd which does not produce
Vnet=0.
This is not the expected result for a short.



You don't understand what i wrote. Rho = +1j is a short if Zo=50+j50 and
Zl= - j50

For our example, rho= -1 , but this is
NOT a short!! As it shouldn't be!

Hint: What is the center of the Smith Chart when it is normalized
to Zo=50+j50?

If you can't answer this question, that's
ok, most people don't understand the Smith very well.



Riddles just do not cut it.


My questions are indeed riddles for those whose don't understand the
concepts.




Feel free to point out the flaws. If you can find none, question why
you hold so tenaciously to revised rho when it does not work.


i just did point out the flaws.

And i will let go of this argument as
soon as someone can give me evidence
that i should. You certainly have not.


I will try the experiment when i get the chance.

Excellent. There is nothing better than seeing it with your own
eyes.


I don't need to see it with my eyes,
when i know you can't get a larger RMS voltage reflected from a capacitor, than
the RMS that charges it.


Slick

I disagree with the demonstration.

Feel free to point out the flaws in the method or the evaluation.


I already did. See other post.


Maybe you are a bit biased?

The experiment and its evaluation has been published in sufficient
detail so that anyone may replicate it. If your lab obtains different
results, please publish them and we can work on why this occurred.


You never measured the incident voltage. And you refused to measure the
end of the inductor, with the capacitor removed (even with the 15 pF, it should
tell us something about Vi).




This may be true, but are you saying that a capacitor can reflect an
RMS voltage wave that is greater than the one that charges it?

Yes indeed. Resonant circuits achieve this with ease.

...Keith


Absolutely incorrect! If capacitance is defined as Coulombs/Volt, then
how are you getting more coulombs than you put in? Remember, i said Root Mean
Square voltage.

How does a capacitor reflect more power than you feed it?

It's almost time for me to cut out of this discussion, if you still don't
understand me.


Slick

TEM stands for transverse electro-magnetic. It means that both the
electric (E) and magnetic (H) fields are transverse (at a right angle)
to the direction of propagation. It refers only to the orientation of
the fields relative to the direction of propagation.

A time-varying E field is never "all alone" -- it's always accompanied
by an H field. Consequently, a voltage wave on a transmission line is
always accompanied by a current wave. I'm certain that Keith didn't mean
to imply otherwise.

Roy Lewallen, W7EL

Richard Harrison wrote:
. . .
Keith also wrote:
"It is a voltage wave which does the travelling."

Sure. That`s why it is called a TEM wave. The E-field is all alone.

Best regards, Richard Harrison, KB5WZI

On Fri, 19 Sep 2003 22:08:01 +0000 (UTC), "Reg Edwards"
wrote:
Richard, is there a conjugate match immediately at the junction between the
transmitter output socket and whatever follows it ?


Even kids know to look both ways before crossing. ;-)

73's
Richard Clark, KB7QHC

In message , Reg Edwards
writes
"Richard Harrison" wrote in message
...
Reg wrote:
"How does each repeater generate its unique pilot tone when a trawler or
earthquake breaks the inner conductor?"

Well, I`ve checked and find that some subsea multiplex units do generate
pilot tones for the purpose I speculated and for others. There is an
"SD" model equipment in which each group modulator generates a pilot
tone used for switching, level adjustment, equalization, etc. If these
tones are being recorded and start losing power, I expect they fade away
but die all at once when the path is interrupted. By examining the
record, it should be possible to see which tones suffered sudden death
and which faded away. There is capacitance in the system and the power
is high-voltage and low current. My information says there is 5500 volts
at each end of the transatlantic cable and that the system current drain
is 389 milliamperes. It has 182 repeaters spaced at about 23 miles. An
equalizer follows each 10th repeater.

I have experience doing similar things with terrestrial radio multiplex.
We used cheap pressure stamping Rust-Rack event recorders to record
breaks in pilot reception. I`ve pored over years of these records, 24
hours at a time.

Best regards, Richard Harrison, KB5WZI

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

OK, Richard, so we've located by some automatic means the cable damage to be
somewhere between the n'th and (n+1)'th repeaters. This is nowhere good
enough for the repair ship captain. He wants to be back in port again for
Christmas. And it costs a million dollars in lost revenue each day the cable
is out of service plus the cost of keeping an 8000-ton ship and its crew at
sea.

The repair ship is just leaving Southampton docks. There's an Atlantic storm
brewing. There are spare lengths of cable and repeaters aboard. This time
they remember to collect the cable jointer. The ship's doctor retires to his
cabin as he is always sea-sick. The ship's Chief Engineer Officer, always a
Scotsman, and the Cable Testing Officer, neither of whom ever seem to have
anything to do, are outside the duty-free bar waiting for it to open.

The captain is pacing up and down the bridge waiting impatiently for a radio
message, cursing the poor fellow at the cable terminal station 500 miles
away on the Scottish rocky Atlantic coast, who is sweating blood twiddling
knobs trying to balance the wideband, 0.05 to 50 Hz, reflection-coefficient
bridge to within plus or minus 0.1 miles along the articial line and
adjusting the artificial fault (R and C in parallel) to within 10 ohms with
a biassing current of 50 milliamps.

After another couple of hours with a sliderule, correcting for seasonal
water temperature, etc., he changes his mind for the tenth time, takes
another swig of scotch, plucks up courage, swallows, and calls the operator.
He asks to send an urgent radio telegram to a cable ship heading westwards
down the English Channel. The message is brief, polite and states "Fault
estimated to be 623.7 miles from Oban". The captain issues a brief
instruction to the duty officer and retires to the loneliness of his cabin.

It is deep dusk. The lights of Plymouth from where Drake set sail 400 years
before can be seen on the starboard horizon. The radar ppi display in the
darkness of the bridge sweeps round monotonously every three seconds clearly
displaying a dozen merchant ships sharing the roughening waters.

The ships engines quietly, monotonously, emit a steady thud, thud, thud,
thud . . . . . . until they merge unnoticed into everybody's
unconsciousness and on deck only the sea and wind can be felt and heard.
----
Reg.





Reg. Please be careful. I nearly choked with laughter on my cornflakes
as I read this this morning. Whatever you are taking, do I need a
prescription, or can I get it over the counter? A great start to the day
(but I'd better get my tax return done before the deadline of the end of
the month).
Ian.
--

Radio913 wrote:
I will try the experiment when i get the chance.

Excellent. There is nothing better than seeing it with your own
eyes.

I don't need to see it with my eyes,
when i know you can't get a larger RMS voltage reflected from a capacitor, than
the RMS that charges it.

Scientists are usually interested in producing models which will
allow them to predict the behaviour of the real world. To do this
it is necessary to check the predictions of the models against
the real world. If you find it unnecessary to do this, then you
are not interested in producing models which can predict real
world outcomes and your models can be anything you want.

But such models won't have much utility.

....Keith

Cecil Moore wrote:

wrote:
Can you expand on why you think a TDR causes me difficulties?
I can't think of any reasons.

There's more than just voltage in those returned pulses.

Yes, there is actually energy in them; easily computed at any point
on the line by using the voltage and current waveform at that point.

As for standing waves, I have no difficulties with forward
and reflected voltage waves. They work perfectly fine.

That takes care of the E-field. But do you think a wave can exist
without an H-field? If not, the wave possesses energy, by definition.
Energy flowing past a point is power.

Your voltage-only waves violate the conservation of energy
principle and the accepted laws of physics for EM waves.

I somewhat sympathize with your dilemma. You have latched on to
these forward and backwards waves for so long that you have started
to believe that they are real and are therefore ascribing to
them all the properties one would expect of a real EM wave such
as current and power.

Some of the authors you quote are not so convinced of their reality.
Consider this quote from sometime back....

"Johnson continues: "We can regard the first term in this
expression as the power associated with the forward-traveling wave,
and the second term as the reflected power (associated with the
rearward-traveling wave)""

As Peter points out in

http://groups.google.ca/groups?q=reg...ing.net&rnum=5

the use of the word "regard" is critical to this passage. Mr Johnson
seems well regarded and it seems likely that if he had intended the
passage to mean "is" he would have used "is" rather than "regard".

Just for a brief moment attempt to relax your hold on forward and
reverse waves and think of the real voltages and currents on the
line. These can be read with real voltmeters and real current meters.
These are the voltages and currents that have to satisfy Es and Hs
and energy flows and power. (And before Richard H pipes up about
directional voltmeters, I take this opportunity to remind him that
all a directional voltmeter actually detects is the real voltage
and current at the point of insertion in the line; all the rest
is computation based on the real voltage and current).

Forward and reflected voltage and current waves are convenient ways
of describing the real voltage and current distributions on the line,
but that does not make them real. And the fact that they correctly
predict the voltages and currents but sometimes fail to predict the
power (when Z0 is not real, for example, but there are many other
examples in simple circuit theory) is a strong indicator that they
are a convenience and not a reality.

Consider a mundane example in the physical world. You have a post
supporting two clotheslines each leaving the post at 90 degrees.
At 135 degrees from the clotheslines is a single guy wire to keep
the post from bending. While for the purposes of analysis you can
pretend that there are two guy wires and this will assist you in
discovering the forces involved, never forget that there is really
only one for otherwise you may be sorely surprised.

Much like this example, the superposition of voltages is a useful
analytical technique, but one must always be aware of its
limitations or one will be lead quite astray.

When one starts believing that the intermediate results represent
reality, trouble begins. It is for this reason that quality authors
use mushy words like "regard" when describing these intermediate
results and not solid words like "is".

....Keith

Cecil Moore wrote:

wrote:
Forget that forward and reverse stuff. That's not what is radiated.

Uh Keith, power delivered to the antenna equals forward power minus
reflected power. I notice you have not provided a way for standing
waves to develop without the existence of reflected waves. Do you
also believe that standing waves don't exist?

I think you have the tail wagging the dog a bit here.

It is the real voltages and currents on the line which deliver the
power to the antenna. These real voltages and currents sometimes
are in a standing wave pattern on the line. This standing wave
pattern can be described by postulating and using forward and
reflected voltage and current waves. Superposition lets you
compute the real voltages and currents but this does not make
the postulated forward and reflected voltages and currents
real.

And this model works so well (unfortunately) that, even though
in general you can not use superposition with power, in the
special case of lines with non-complex Z0, it even works for
power. This fluke, of course, serves to reinforce in the minds
of many the 'reality' of these forward and reflected powers.

When 'the many' encounter the general case, they are quite
perturbed that superposition no longer works for power and
strive mightily to modify the flawed model to account for
the discrepancies rather than just letting go of the model.

The reality is that forward and reflected voltage and current
waves are a convenience that assist in solving problems but
only real voltages and currents move energy.

....Keith

Cecil Moore wrote:

wrote:
When you use a pulse, p(t) = v(t) * i(t) shows the pulse going
by and coming back too, if it reflects. But for that, you have to
look at things in the time domain, something a number of readers
here refuse to do for continuous sinusoidal excitation. When you
look at continuous sinusoidal excitation in the time domain all
the information you need about power is provided without having
to resort to Pfwd and Prev.

Yes, but those steady-state shortcuts often lead to a distorted
view of reality. Exactly what magic happens at the instant when a
system goes from the transient state to steady-state?

I am unsure where you construed "steady-state" in the original
passage. It is, of course, in the time domain that one can explore
the non-steady state mature of the system.

....Keith

Richard Harrison wrote:

Keith wrote:
"---it will turn out that there is no value in forward and reverse power
on a line with non-real Zo."

The Bird wattmeter works well enough on coax lines used between the
usual transmitter and antenna. Loss produces reactance in coax. We don`t
seek lossy coax. If it becomes lossy, the line is likely to be replaced.

You, of course, are correct. I overstate the case slightly in
an attempt to get readers to let go of their model. Once they
are free of forward and reverse power as being an accurate
model of reality, they are then free to understand what a
Bird really indicates.

And it is useful for lines with near real impedances (as many
RF lines are) as a TLI. And in cases where reflected power is
near zero, it will even give a hint as to how much power is
being delivered to the load (within 5% of full scale).

The question is, does the reader understand how it works,
why it is useful and its limitation; or does the reader
believe the markings on the scale and think that it is
actually MEASURING the power in a forward and reverse
wave.

....Keith

I don't need to see it with my eyes,
when i know you can't get a larger RMS voltage reflected from a capacitor,
than
the RMS that charges it.

Scientists are usually interested in producing models which will
allow them to predict the behaviour of the real world. To do this
it is necessary to check the predictions of the models against
the real world. If you find it unnecessary to do this, then you
are not interested in producing models which can predict real
world outcomes and your models can be anything you want.

But such models won't have much utility.

...Keith



"Scientists" are also human too, and tend to want to disregard or not even
try to measure data that may contradict their models. This makes them feel
comfortable that they are "right".


Slick

wrote:
This standing wave
pattern can be described by postulating and using forward and
reflected voltage and current waves. Superposition lets you
compute the real voltages and currents but this does not make
the postulated forward and reflected voltages and currents
real.

Can you think of any other way for standing waves to exist
except for the superposition of a forward wave and a reverse
wave? Until you can describe how standing waves can even exist
without a forward wave and a reverse wave, it doesn't do any
good to deny their existence.
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

Cecil Moore wrote:

wrote:
I somewhat sympathize with your dilemma. You have latched on to
these forward and backwards waves for so long that you have started
to believe that they are real and are therefore ascribing to
them all the properties one would expect of a real EM wave such
as current and power.

So what causes standing waves if there are no forward and backwards
waves?

When you solve the differential equations describing the circuit
with distributed capacitance, inductance, resistance and conductance,
given the excitation and boundary conditions, you discover that
the voltage and current distributions along the line form a
standing wave. No need for reflections at all.

It is a whole lot more convenient using the reflection model
though.

Just for a brief moment attempt to relax your hold on forward and
reverse waves and think of the real voltages and currents on the
line.

I will just as soon as you demonstrate how to generate standing
waves without the existence of a forward wave and reverse wave.

OK. Go for it.

....Keith

Radio913 wrote:

I don't need to see it with my eyes,
when i know you can't get a larger RMS voltage reflected from a capacitor,
than
the RMS that charges it.

Scientists are usually interested in producing models which will
allow them to predict the behaviour of the real world. To do this
it is necessary to check the predictions of the models against
the real world. If you find it unnecessary to do this, then you
are not interested in producing models which can predict real
world outcomes and your models can be anything you want.

But such models won't have much utility.

"Scientists" are also human too, and tend to want to disregard or not even
try to measure data that may contradict their models. This makes them feel
comfortable that they are "right".

I completely agree.

So can you overcome your "tend[ancy] to want to disregard or
not even try to measure data that may contradict their models."?

....Keith

| wrote:
| ...
| As has been aptly demonstrated in another thread, it does
| not work for lines with complex Z0.
| ...

Dear Keith,

Could you tell me please
in which thread?

Sincerely,

pez
SV7BAX

pez wrote:

| wrote:
| As has been aptly demonstrated in another thread, it does
| not work for lines with complex Z0.

Could you tell me please in which thread?

Seems he is talking about that third power term in Chipman's
equation, the one caused by the resonance effect between the
feedline's Z0 reactance and the load's reactance.
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

Reg Edwards wrote:

A so-called directional wattmeter or SWR meter merely responds to the
magnitude of a reflection coefficient usually, but not necessarily, relative
to 50 + j0 ohms. Half of the information, the angle, is discarded without
being aware of its existence.


Not exactly correct.

The phase information is not displayed explicitly
on a scaler instrument like the Bird meter, but
phase is definitely involved in the principles of
operation of the directional coupler.

Very seldom, if ever, do we care a feather or a
fig what the exact phase value is, but the
directional coupler is not balanced unless the
phase is zero.

All automatic antenna tuners utilize this fact.

Bill W0IYH

Reg Edwards wrote:
A so-called directional wattmeter or SWR meter merely responds to the
magnitude of a reflection coefficient
[...]
Just a little box containing assumptions, preconceived notions,
suppositions, ambiguitiues and a lot of imagination.

The box responds only to the voltage and the current on the line. Those
are the only *physical* things it responds to. All the rest is about
ideas.

The basic design of the instrument is inspired by the idea of forward
and reflected V and I waves, and the idea of the reflection
coefficient. The circuit is designed so that the meter displays the
magnitude of the reflection coefficient on a linear scale.

The further *calibration* of the meter scale in terms of SWR and
forward/reflected power is then inspired(?) by yet more ideas - which
Reg so aptly describes as a mix of "assumptions, preconceived notions,
suppositions, ambiguities and a lot of imagination."


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
Editor, 'The VHF/UHF DX Book'
http://www.ifwtech.co.uk/g3sek

"William E. Sabin" wrote Reg Edwards wrote:

A so-called directional wattmeter or SWR meter merely responds to the
magnitude of a reflection coefficient usually, but not necessarily,
relative
to 50 + j0 ohms. Half of the information, the angle, is discarded
without
being aware of its existence.


Not exactly correct.

The phase information is not displayed explicitly
on a scaler instrument like the Bird meter, but
phase is definitely involved in the principles of
operation of the directional coupler.

Very seldom, if ever, do we care a feather or a
fig what the exact phase value is, but the
directional coupler is not balanced unless the
phase is zero.

All automatic antenna tuners utilize this fact.

Bill W0IYH

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

Bill, why the unnecessarily complications?

It is possible to imagine the so-called SWR meter is telling you the
imaginary value of the SWR on a non-existent transmission line. But it's
hardly of educational value when novices, even experienced engineers, are
trying to understand what the reading really means. It's as confusing and
as untruthful as Blair.

Why don't we accept the simple fact that the meter tells us only whether the
transmitter is loaded with a resistance of a particular value or not. Which
is no more nor less than what the instrument on the front panel of your
transceiver is provided for.

Then we can forget all about SWR, fwd and reflected power, until needed on
real ines. Change the name of the meter to TLI.
---
Reg, G4FGQ

"Reg Edwards" wrote in message
...
It is possible to imagine the so-called SWR meter is telling you the
imaginary value of the SWR on a non-existent transmission line. But it's
hardly of educational value when novices, even experienced engineers, are
trying to understand what the reading really means. It's as confusing and
as untruthful as Blair.

Why don't we accept the simple fact that the meter tells us only whether
the
transmitter is loaded with a resistance of a particular value or not.
Which
is no more nor less than what the instrument on the front panel of your
transceiver is provided for.

Then we can forget all about SWR, fwd and reflected power, until needed on
real ines. Change the name of the meter to TLI.
---
Reg, G4FGQ

Amen to that. I turned down the power on my transmitter, and measured P
forward and P rev while feeding about 100 feet of unterminated 9913. I then
REMOVED the coax; i.e. there was nothing connected to the output side of the
meter. Still measured the same Pf and Pr. (Daiwa meter)

Tam/WB2TT

Yet you've found it impossible to explain, either numerically or in
equation form, which "power wave" these "interference terms" belongs to,
or how this "interference" comes about in your model of superposing,
traveling power waves.

The explanation is indeed simple -- as long as you can continue to avoid
explaining it.

Roy Lewallen, W7EL

Cecil Moore wrote:
wrote:

Regardless of whether there is an alternative explanation,
you should reject the reflected power model because....
In general, IT DOES NOT WORK.


In general, our feedline losses are low enough that it does
work. In general on HF, we are dealing with near-resistive
Z0's and Z0-matched systems.

As has been aptly demonstrated in another thread, it does
not work for lines with complex Z0.


Actually it does. All one has to do is take the power interference
terms into account.
. . .

Tarmo Tammaru wrote:
Amen to that. I turned down the power on my transmitter, and measured P
forward and P rev while feeding about 100 feet of unterminated 9913. I then
REMOVED the coax; i.e. there was nothing connected to the output side of the
meter. Still measured the same Pf and Pr. (Daiwa meter)

Of course, you were simply getting a same-cycle reflection. The reflected
wave model is consistent. If the open-circuit is at the transmitter terminal,
all the power is reflected immediately.
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

Roy Lewallen wrote:

Yet you've found it impossible to explain, either numerically or in
equation form, which "power wave" these "interference terms" belongs to,
or how this "interference" comes about in your model of superposing,
traveling power waves.

For the record, I don't superpose things that lack phase. But if you
turn on two 100 watt light bulbs, don't you double the light output?
This stuff is all explained in _Optics_, by Hecht.

The explanation is indeed simple -- as long as you can continue to avoid
explaining it.

It is all explained in Chipman's "Transmission Lines". Please take the time
to read it and understand it. Just as the voltage and current increase depending
upon the 'Q' of a resonant circuit, the same thing happens with reactive
transmission lines. I am not going to waste my time explaining such an easy
concept. You probably can simulate the situation by drawing the dividing
plane between the cap and the resistor in the following circuit.
|
RF source----//----capacitor---|---resistor------inductor-------+
| | |
+-------//----------------|--------------------------------+
|
plane

The voltage across the capacitor or inductor, depending upon the 'Q' of
the circuit, can be greater than the RF source voltage. You can add 1WL
of transmission line at the '//' point without changing anything. In this
case, the energy exchanged between the capacitor and inductor travels through
the resistor and contributes to power dissipation in the radiation resistance
(if that is what that resistance is). Like I said before, it's a no-brainer.
Once I read Chipman's explanation, it was as clear as day.
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

"Scientists" are also human too, and tend to want to disregard or not
even
try to measure data that may contradict their models. This makes them
feel
comfortable that they are "right".

I completely agree.

So can you overcome your "tend[ancy] to want to disregard or
not even try to measure data that may contradict their models."?

...Keith



I'll think about it after you tell us what you get when you measure the
end of the inductor.


Slick

Keith wrote:
"Scientists are usually interested in producing models which will allow
them to predict the behaviour of the real world.

True. Models must be adjusted to reality, not the other way around. But,
once the model is verified it becomes useful.

You don`t have to measure the area of a rectangle with a planimeter once
you know that area is the product of the length and width of the
rectangle.

Best regards, Richard Harrison, KB5WZI