Standing morphing to travelling waves. was r.r.a.a Laugh Riot!!!
 

Michael Coslo wrote:

...
Non sequitar here?

I do care about why and how the antenna works. I just don't agree with
AI4QJ's premise that Eznec is for discussion purposes only. It isn't, it
works just fine for design and implementation of them also.

Its a good tool for design of antennas. It gives me the data I need and
the expected outcome. I've designed simple antennas using "personal
level math" too. I don't do that much any more. I did the calculations
on paper too. I don't know if that makes them better than if they were
done using a calculator though.

There are some people that
operate at 27MHz who don't care how their radios work, only that they
can peg your meter at 10 pounds.

And there are some sanctimonius people out there who are educated
orders of magnitude beyond their intelligence, ready to throw out veiled
insults at the drop of a hat.......

Fortunately no one like that is in this conversation, eh?

- 73 de Mike N3LI -

I really don't want to be involved, the complexities of this argument
are too great a demand for my time, and I lack the deep understanding to
add beyond where others have already gone (indeed, they have gone well
beyond my understandings--I play a game of catch-up.)

However, I don't believe anyone is actually dismissing EZNEC. I know of
no better which does what EZNEC does. Nor am I aware of anyone actually
attacking the personalities behind or around EZNEC--it is the premises,
formulas, equations EZNEC is based on which harbors the discussion ...
and such discussion cannot hurt.

I believe the above is most accurate--just now and then a temper might
flare ...

Regards,
JS

Standing morphing to travelling waves. was r.r.a.a Laugh Riot!!!
 

Cecil Moore wrote:
On Jan 9, 3:33 pm, Gene Fuller wrote:
When you get back to the wilds of Texas go check out some rural power
lines. Count the number of power factor correcting capacitors you see. I
bet it is a lot less than the equivalent of one per city block. Power
factor correcting capacitors are intended to correct for reactive loads,
such as motors, not for reflections or standing waves on open ended
power transmission lines.

Within the city limits of my home town of Madisonville, TX, there is
approximately one capacitor every city block. I had one in my front
yard. But the exact number and distances do not matter one iota. Those
capacitors exist to neutralize the inductive reactance in the system
at the load. I use exactly the same method to twist the feedpoint
impedance of my 75m Bugcatcher to 50 ohms.

You said: "Power factor correcting capacitors are intended to correct
for reactive loads,"

:-) Reactive loads cause reflections. The opposite reactance reduces
reflections. Does that scheme of matching a transmission line to a
load sound familiar? :-) My Bugcatcher antenna has about 25=j25 ohm
feedpoint impedance on 40m. I install a -j50 cap from antenna to
ground to achieve 50+j0 at the feedpoint. That's exactly what the
power company capacitors do.

Reflections *ARE* power factor problems. When the power company brings
the power factor to unity, they have eliminated reflections and turned
the system into a traveling wave energy delivery system. That you do
not recognize the similarity between VARS and standing waves is really
strange indeed. Standing waves contain nothing except VARS.
--
73, Cecil, w5dxp.com

You never give up, do you? Even when you are caught in an utter lie. You
know exactly what the capacitors are for, and it isn't to control
transmission line reflections from open ends of the line.

73,
Gene
W4SZ

Standing morphing to travelling waves, and other stupid notions
 

Cecil Moore wrote:
On Jan 9, 3:30 pm, Gene Fuller wrote:
So do we now have a new requirement for waves and photons that there
must be *net* energy flow?

It's not a new requirement, Gene, just a very old requirement of
physics. Photonic, i.e. EM waves, do not flow back and forth as you
are implying. As long as the medium is homogeneous, i.e. doesn't
change, a photon travels at the speed of light in one direction in a
medium. So yes, net energy flow is absolutely a requirement for
photons.

EM waves *are* photons and do not vibrate back and forth in a medium.
They travel in one direction at the speed of light in the medium until
they encounter an impedance discontinuity. Virtually any physics book
with a diagram of the EM wave E-field and H-field will show the
direction of travel as one direction without the "one step forward and
one step back" concept that you are proposing.

You claimed that standing waves cannot be real waves because they cannot
obey photon rules. I easily demonstrated that idea is incorrect.v

All you demonstrated was your ignorance of the nature of photons. Your
analysis was incorrect. You are seeing the standing wave illusion and
assuming an impossibility of physics. It is very clear that you and
others simply do not understand the nature and physics of photons and
photonic waves.
--
73, Cecil, w5dxp.com

It is really amazing that you can make up so many requirements that are
completely unknown to the rest of the world. Is that a Mensa thing?

73,
Gene
W4SZ

Standing morphing to travelling waves, and other stupid notions
 

Richard Harrison wrote:
Jim Kelley, AC6XG wrote:
"On what page has Dr. Hecht written "A standing wave is a different kind
of electromagnetic wave?"

In "Schaum`s College Physics Outline" by Bueche & Hecht on page 214 is
written:
"Standing Waves:....These might better not be called waves at all since
they do not transport energy and momentum."

I hope my question was not interpretted to imply that standing waves
transport energy and momentum.

Thanks for the page number.

73, ac6xg

Standing morphing to travelling waves. was r.r.a.a Laugh Riot!!!
 

Gene Fuller wrote:

...
You never give up, do you? Even when you are caught in an utter lie. You
know exactly what the capacitors are for, and it isn't to control
transmission line reflections from open ends of the line.

73,
Gene
W4SZ

I do know it has been speculated that events on the sun have caused
"phenomenon" in utility lines to the point of power outages. Indeed, I
think there is still some mystery about why this occurs. And, I know
power companies have tried some fixes to these ... decades ago I had
line noise to the point I contacted the power company. They sent
someone out and, I thought, installed some sort of cap/filter on the
line--anyway, they did "stick something up there you could see." I did
notice a slight improvement--but finally ended up giving up the battle
with them ... a move to a quieter location changed everything.

Regards,
JS

Standing morphing to travelling waves, and other stupid notions
 

Cecil Moore wrote:

On Jan 9, 3:13 pm, Jim Kelley wrote:

On what page has Dr. Hecht written "a standing wave is a different
kind of electromagnetic wave"?


Since I didn't say that Dr. Hecht said that, it must be a rhetorical
question. Here's what Dr. Hecht did say: In "Schaum`s College Physics
Outline" by Bueche & Hecht on page 214 is written: "Standing
Waves:....These might better not be called waves at all since they do
not transport energy and momentum." (Thanks to Richard Harrison for
that quote.)

Hi Cecil - please note that Dr. Hecht does not post to this newsgroup.
If you follow this thread back, you will find that you were the one
who wrote "a standing wave is a different kind of electromagnetic wave".

I agree with Dr. Hecht. Standing waves should not be
called waves at all since they do not meet the definition and
requirements for EM waves.

And so do I. But as I said, I am not disputing anything that Dr.
Hecht has written in his textbooks. Though, there are more elegantly
written physics books.

I asserted that expression for the sum of traveling waves and the
expression for the resulting standing wave pattern are related by trig
identity, as per page 140 of the 28th Edition of the CRC Standard
Mathematical Tables Handbook.


Sorry Jim, that's not what you said. You asked if I recognized the
trig identity that (presumably) equated a standing wave to a traveling
wave. If that was not your meaning, it is time to say exactly what
meaning I was supposed to assume.

See above.

ac6xg

Standing morphing to travelling waves. was r.r.a.a LaughRiot!!!
 

Hi Roy,

This helps a lot. I much better understand exactly how you are running the calculations.

I have just three comments/suggestions mixed into your posting.

On Wed, 09 Jan 2008 14:24:23 -0800
Roy Lewallen wrote:

Roger Sparks wrote:

Using the reflection point as the zero reference seems to correspond with an observation you made about the end of the line controlling the SWR.

The choice of zero reference is entirely arbitrary; any point on the
line, or off the line, for that matter, can be used. I used the input
end of the line as the x = 0 reference, so my equations are correct only
when that reference is used. The choice of a reference has no effect on
the SWR or any other aspect of line operation; it simply modifies the
equations.

For example, my equations for the first forward and first reflected
voltage wave we

vf1(t, x) = sin(wt - x)
vr1(t, x) = Gl * sin(wt + x)

and for the second set:

vf2(t, x) = Gs * sin(wt - x)
vr2(t, x) = Gs * Gl * sin(wt + x)

where here I've explicitly shown the source and load reflection
coefficients as Gs and Gl respectively. They were 0.5 and 1 in my second
analysis (the one with a 150 ohm resistor at the source).

The more general case where the line is some length L, rather than the
integral number of wavelengths in the example,

vf1(t, x) = sin(wt - x)
vr1(t, x) = Gl * sin(wt + x - 2L)

vf2(t, x) = Gs * Gl * sin(wt - x - 2L)
vr2(t, x) = Gs * Gl^2 * sin(wt + x - 4L)

Should we add an L to vf1(t, x, L) to keep the notation consistant in that we are considering 3 phase components. Rewriting,
vf1(t, x, L) = sin(wt - x + 0*L) (input point is congruent with refection point)
vr1(t, x, L) = Gl * sin(wt + x - 2L)(2L evaluates the entire line travel time)

In general,

(1) vfn(t, x) = (Gs * Gl)^n * sin(wt - x - 2nL)
(2) vrn(t, x) = Gl * (Gs * Gl)^n * sin(wt + x - (2n + 1)L)

where L is expressed in the same units as x and wt (degrees or radians).

These equations are correct with x being the distance from the input end
of the line.

I get your drift here. You are writting the general equation as if the first event is event zero, computer programming style.

Shouldn't these be written like this, changing the term "(2n + 1)L"?

(1) vfn(t, x) = (Gs * Gl)^n * sin(wt - x - 2nL)
(2) vrn(t, x) = Gl * (Gs * Gl)^n * sin(wt + x - 2(n+1)L)


You could, as I mentioned, use a different reference, for example x' = L
- x, where L is the line length in radians or degrees (same units as x
and wt). Then you have, simply by substituting L - x' for x:

vf1(t, x') = sin(wt - L + x')
vr1(t, x') = sin(wt + L - x' - 2L) = sin(wt - L - x')

and so forth, and for the general case,

(3) vfn(t, x') = (Gs * Gl)^n * sin(wt + x' - (2n + 1) * L)
(4) vrn(t, x') = (Gs * Gl)^n * sin(wt - x' - 2nL)

or, you can use x for the forward wave and x' for the reverse wave or
vice-versa in order to reference to the point the wave was reflected
from or where it will be reflected from. Any combination of the
equations is equally valid and will give correct results. You can't,
however, simply redefine the reference point without a corresponding
change in the equation. In general, equation 1 and equation 3 will give
different results if you put in the same value for x and x'; likewise
equations 2 and 4. There are some special cases, as you showed, where
you can change the reference without modifying the equations and not
have any impact on the sum of the waves. However, you can see from the
equations that this won't usually work.

Yes, the discussion becomes confusing quickly. If we were to have a rigorus discussion, we would need diagrams locating the points and directions. Lacking that, we are adrift.


The general case with complex reflection coefficients and arbitrary line
length is mathematically a little more difficult than the simple example
I worked earlier. Not only does each reflection have a different
amplitude than the previous one, it also has a different phase angle,
due to the line length and the reflection coefficients. Consequently,
the simple a / (1 - r) formula I used for summing the infinite series of
waves can't be applied to the equations in the form I used. This is
where a change to phasor notation is really beneficial, since the phase
delay simply becomes e raised to an imaginary exponent which can be
treated more conveniently than its constituent sine and cosine
functions. With phasor notation, the summing formula can be used even
for the general case to find the steady state results from the
individual reflected waves. There's a very excellent treatment of this
in Chipman's _Transmission Lines_ (Schaum's Outline Series). He does
just about exactly what I did in my earlier posting, except for the
general case and using phasors rather than time representations. It's an
excellent text and reference, and I highly recommend it for anyone
seriously interested in transmission lines.

Roy Lewallen, W7EL

This has been very productive for me Roy. I am gaining a much better appreciation for the whole subject, especially the use of phasors. Your use of the phase angle (posted with the corrections) was particularly helpful. I am planning to find Chipman's book.

Thanks for your efforts.

73, Roger, W7WKB

Standing morphing to travelling waves, and other stupid notions
 

On Jan 9, 11:22 pm, Roy Lewallen wrote:
Just what is a "wave", anyway? Are there different "kinds" of
electromagnetic wave?

Take a look at the E-field, H-field, and direction of travel for an EM
(photonic) wave. An RF standing wave does not behave like an EM wave
nor does it meet the definition of an EM wave which can be represented
by a Poynting vector. The Poynting vector for an RF standing wave has
a magnitude of zero and no direction.
--
73, Cecil, w5dxp.com

Standing morphing to travelling waves. was r.r.a.a Laugh Riot!!!
 

Roger Sparks wrote:
Roy Lewallen wrote:
. . .
The more general case where the line is some length L, rather than the
integral number of wavelengths in the example,

vf1(t, x) = sin(wt - x)
vr1(t, x) = Gl * sin(wt + x - 2L)

vf2(t, x) = Gs * Gl * sin(wt - x - 2L)
vr2(t, x) = Gs * Gl^2 * sin(wt + x - 4L)

Should we add an L to vf1(t, x, L) to keep the notation consistant in that we are considering 3 phase components. Rewriting,

Yes, that's fine. It can be viewed as either a variable or a constant,
but it won't change during the course of a single analysis.

vf1(t, x, L) = sin(wt - x + 0*L) (input point is congruent with refection point)

It's not necessary to explicitly add the 0*L term, even if you consider
vf to be a function of a variable L. And it adds unnecessary clutter and
potential confusion without any effect on the result.

vr1(t, x, L) = Gl * sin(wt + x - 2L)(2L evaluates the entire line travel time)

The equation is correct and what I wrote. I don't understand the
parenthetical comment.

In general,

(1) vfn(t, x) = (Gs * Gl)^n * sin(wt - x - 2nL)
(2) vrn(t, x) = Gl * (Gs * Gl)^n * sin(wt + x - (2n + 1)L)

where L is expressed in the same units as x and wt (degrees or radians).

These equations are correct with x being the distance from the input end
of the line.

I get your drift here. You are writting the general equation as if the first event is event zero, computer programming style.

Sorry, I don't know what event you're talking about. And it's not
"computer programming style", but standard notation as you'll find in
any text. I am making the assumption that the line is initially
discharged, if that's what you mean.

Shouldn't these be written like this, changing the term "(2n + 1)L"?

(1) vfn(t, x) = (Gs * Gl)^n * sin(wt - x - 2nL)
(2) vrn(t, x) = Gl * (Gs * Gl)^n * sin(wt + x - 2(n+1)L)


You're right. I made an error -- thanks for spotting it. The reflected
wave has an additional 2L delay relative to the corresponding forward
wave, and I didn't write it correctly. I apologize for the error.

You could, as I mentioned, use a different reference, for example x' = L
- x, where L is the line length in radians or degrees (same units as x
and wt). Then you have, simply by substituting L - x' for x:

vf1(t, x') = sin(wt - L + x')
vr1(t, x') = sin(wt + L - x' - 2L) = sin(wt - L - x')

and so forth, and for the general case,

(3) vfn(t, x') = (Gs * Gl)^n * sin(wt + x' - (2n + 1) * L)
(4) vrn(t, x') = (Gs * Gl)^n * sin(wt - x' - 2nL)

Equation 3 has the same error.

or, you can use x for the forward wave and x' for the reverse wave or
vice-versa in order to reference to the point the wave was reflected
from or where it will be reflected from. Any combination of the
equations is equally valid and will give correct results. You can't,
however, simply redefine the reference point without a corresponding
change in the equation. In general, equation 1 and equation 3 will give
different results if you put in the same value for x and x'; likewise
equations 2 and 4. There are some special cases, as you showed, where
you can change the reference without modifying the equations and not
have any impact on the sum of the waves. However, you can see from the
equations that this won't usually work.

Yes, the discussion becomes confusing quickly. If we were to have a rigorus discussion, we would need diagrams locating the points and directions. Lacking that, we are adrift.

It depends on your ability to visualize equations, which usually
improves as you work with them. But sketches of the waves are definitely
very helpful in keeping track of what's going on. I hope my little
program will also prove helpful for this.

This has been very productive for me Roy. I am gaining a much better appreciation for the whole subject, especially the use of phasors. Your use of the phase angle (posted with the corrections) was particularly helpful. I am planning to find Chipman's book.

Thanks for your efforts.

You're welcome. I'm glad to help when I can. Chipman's book might be
hard to find, but it's well worth the search. I have more than a dozen
texts dealing with transmission lines, but Chipman's has material, like
the concise development of steady state from startup, that you'll find
in few others.

I haven't used phasors in these postings at all, but would have to in
order to sum the waves for the general case. In phasor notation,

vfn(t, x) = (Gs * Gl)^n * exp(j(-x - 2nL))
vrn(t, x) = Gl * (Gs * Gl)^n * exp(j(x - 2(n + 1)L))

where Gs and Gl are complex. So the ratio of successive terms vfn(t, x)
/ vfn-1(t, x) = vrn(t, x) / vrn-1(t, x) is a multiplier term Gs * Gl *
exp(-j2nL). So we can use the formula for summing an infinite series to get

vf(ss)(t, x) = vf1 / (1 - Gs * Gl * exp(-j2nL))
vr(ss)(t, x) = vr1 / (1 - Gs * Gl * exp(-j2nL))

which can be evaluated as complex numbers and converted back to time
functions for evaluation. While the summation of the infinite series
could almost certainly be done by clever application of trig identities,
it's trivial with phasors.

Roy Lewallen, W7EL

Standing morphing to travelling waves, and other stupid notions
 

Cecil Moore wrote:

An RF standing wave does not behave like an EM wave
nor does it meet the definition of an EM wave which can be represented
by a Poynting vector. The Poynting vector for an RF standing wave has
a magnitude of zero and no direction.

So much for the Poynting vector of a position envelope. What are your
thoughts regarding the Poynting vector for a time varying envelope of
an electromagnetic wave? :-)

ac6xg

Standing morphing to travelling waves, and other stupid notions
 

On Thu, 10 Jan 2008 11:25:56 -0800, Jim Kelley
wrote:

the Poynting vector for an RF standing wave has
a magnitude of zero and no direction.

So much for the Poynting vector of a position envelope. What are your
thoughts regarding the Poynting vector for a time varying envelope of
an electromagnetic wave? :-)

Hi Jim,

Imagine even more the dilemma this puts the dipole in! It has
suddenly collapsed into a shielded, dummy load. ;-)

DAMN! Did my TV screen just go blank?

73's
Richard Clark, KB7QHC

Standing morphing to travelling waves, and other stupid notions
 

On 10 Jan, 11:25, Jim Kelley wrote:
Cecil Moore wrote:
An RF standing wave does not behave like an EM wave
nor does it meet the definition of an EM wave which can be represented
by a Poynting vector. The Poynting vector for an RF standing wave has
a magnitude of zero and no direction.

So much for the Poynting vector of a position envelope. *What are your
thoughts regarding the Poynting vector for a time varying envelope of
an electromagnetic wave? *:-)

ac6xg

Keep going guys. You are nearly at the end. Must be! Richard has
already started on "I knew that all the time" in an effort to take all
the credit. Mohammed has come to the mountain
and found that Richard the bard was already there.LOL
Art Unwin...KB9MZ...XG(uk)

Standing morphing to travelling waves, and other stupid notions
 

On Jan 10, 1:25 am, Roy Lewallen wrote:
After reading this, I understand why you find Art's material interesting.

But, what's a "wave"?

A wave is any periodic function f(x) where f(x) = amplitude and whose
period X defines one cycle.

Standing morphing to travelling waves, and other stupid notions
 

Standing morphing to travelling waves, and other stupid notions
 

AI4QJ wrote:

The single pulse can be decribed by its fourier series a superposition of
sinudoidal waves so you would actually be sending wave(S) down the line, of
varying harmonic frequencies, but only for the time defined by the pulse
width.

So a sine wave consisting of only two cycles is considered a periodic
function? How about one cycle? Half cycle? Does a truncated sine wave
fit the proposed definition of f(x) where x is the period? Would the
pulse then be one wave or an infinite number of waves (since the
spectrum of any time-limited function is infinite in width)?

Wouldn't it be fun to calculate the power in each of the infinite number
of sine waves and add them together like Cecil does to get the total
power? Boy, I'll bet you'd have a *lot*!

Roy Lewallen, W7EL

Standing morphing to travelling waves. was r.r.a.a Laugh Riot!!!
 

On Jan 10, 10:55 am, Gene Fuller wrote:
.. You never give up, do you? Even when you are caught in an utter
lie. You
know exactly what the capacitors are for, and it isn't to control
transmission line reflections from open ends of the line.

I'm sorry, Gene, but I cannot alleviate your ignorance with one
posting. Given a voltage phasor and a current phasor with a phase
angle between them, there is absolutely no way to distinguish between
a mismatch and a reflection. The purpose of those power factor
capacitors on the power line poles is to turn those transmission lines
into money-making traveling wave delivery systems rather than allow
money-losing standing wave systems. Please stop your emoting long
enough to realize what I have said is true.

If the capacitors were not there, the inductive loads would cause
reflections just as they do on an RF transmission line. The only
difference is that the 60 Hz transmission line is a small fraction of
a wavelength. If you scaled the 60 Hz system to 6 MHz, all the same
laws of physics would apply and the similarities would be readily
apparent.
--
73, Cecil, w5dxp.com

Standing morphing to travelling waves, and other stupid notions
 

On Jan 10, 10:59 am, Gene Fuller wrote:
.. It is really amazing that you can make up so many requirements that
are
completely unknown to the rest of the world. Is that a Mensa thing?

Methinks you need to study and comprehend the nature of photons and
photonic waves.
--
73, Cecil, w5dxp.com

Standing morphing to travelling waves, and other stupid notions
 

On Jan 10, 11:08 am, Jim Kelley wrote:
If you follow this thread back, you will find that you were the one
who wrote "a standing wave is a different kind of electromagnetic wave".

I don't remember saying that and I apologize if I ever did. What I
remember saying is that an RF standing wave doesn't meet the
definition of an EM wave which is essentially the same thing that Dr.
Hecht said: "Standing Waves:....These might better not be called waves
at all since they do not transport energy and momentum."

RF standing waves, unlike other EM waves, do not transport energy and
momentum at the speed of light in the medium. Therefore, they are
technically not EM (photonic) waves.
--
73, Cecil, w5dxp.com

Standing morphing to travelling waves, and other stupid notions
 

On Jan 10, 2:25 pm, Jim Kelley wrote:
So much for the Poynting vector of a position envelope. What are your
thoughts regarding the Poynting vector for a time varying envelope of
an electromagnetic wave? :-)

If the wire runs in the 'x' direction, the standing wave phasors
rotate only in the 'yz' plane. Since the Poynting vector is always
normal to the E-field and H-field, seems the instantaneous value of
the Poynting vector for a standing wave is still zero.
--
73, Cecil, w5dxp.com

Standing morphing to travelling waves, and other stupid notions
 

On Jan 10, 2:34 pm, Richard Clark wrote:
Imagine even more the dilemma this puts the dipole in! It has
suddenly collapsed into a shielded, dummy load. ;-)

Sorry, the dipole standing waves are only about 80% of the energy on
the antenna. The other 20% of the energy is radiated (or lost to
heat). If the waves on the 1/2WL dipole were 100% standing waves, the
antenna would have a zero feedpoint impedance, but it doesn't
--
73, Cecil, w5dxp.com
..

Standing morphing to travelling waves, and other stupid notions
 

On Jan 10, 7:02 pm, Roy Lewallen wrote:
Wouldn't it be fun to calculate the power in each of the infinite number
of sine waves and add them together like Cecil does to get the total
power?

Optical scientists have been "adding" EM wave power densities for
centuries using the irradiance equation which includes the phase angle
between the E-fields. I'm surprised you are still ignorant of that
fact of physics.
--
73, Cecil, w5dxp.com

Standing morphing to travelling waves, and other stupid notions
 

On Thu, 10 Jan 2008 17:35:42 -0800 (PST), Cecil Moore
wrote:

dipole standing waves are only about

Ah, yes! The devil is in the "about" where Cecil can prove a new
fundamental law with errors of only 50%. Naturally, we will have to
subscribe to newsletters to find the data. Let me anticipate the next
burst of evidence:
"But you MUST admit that 1 amp through 1 ohm is 1 volt.
Denying this makes you a liar!"

73's
Richard Clark, KB7QHC

Standing morphing to travelling waves, and other stupid notions
 

Cecil Moore wrote:

I don't remember saying that and I apologize if I ever did. What I
remember saying is that an RF standing wave doesn't meet the
definition of an EM wave which is essentially the same thing that Dr.
Hecht said: "Standing Waves:....These might better not be called waves
at all since they do not transport energy and momentum."

You could shortcut the whole process and just have Dr. Hecht post his
ideas here instead. I bet ya anything there would be far fewer
arguments about physics. :-)

RF standing waves, unlike other EM waves, do not transport energy and
momentum at the speed of light in the medium. Therefore, they are
technically not EM (photonic) waves.

Technically, they're just spatial interference patterns, so of course
they don't propagate energy. They're like any other spatial
interference pattern in that regard.

ac6xg

Standing morphing to travelling waves, and other stupid notions
 

Cecil Moore wrote:

On Jan 10, 2:25 pm, Jim Kelley wrote:

So much for the Poynting vector of a position envelope. What are your
thoughts regarding the Poynting vector for a time varying envelope of
an electromagnetic wave? :-)


If the wire runs in the 'x' direction, the standing wave phasors
rotate only in the 'yz' plane.

A standing wave is an amplitude vs position envelope. An amplitude vs
time envelope is modulation! :-)

ac6xg

Standing morphing to travelling waves. was r.r.a.a Laugh Riot!!!
 

On Jan 9, 10:46*pm, Cecil Moore wrote:
On Jan 9, 3:33 pm, Gene Fuller wrote:
Reflections *ARE* power factor problems. When the power company brings
the power factor to unity, they have eliminated reflections and turned
the system into a traveling wave energy delivery system.

This would not be quite correct. The power factor correction
capacitors make the load impedance real, they do not match
the load to the impedance of the distribution line. As such,
they have not eliminated reflections.

Since the customer decides on the load impedance (infinity
when the equipment is disconnected), the power company is
always dealing with mismatched loads. And does not seem
too concerned as long as the load is close to real.

It might be instructive to consider some real transmission
systems. From La Grande-2 (5.6 GW) or Churchill Falls (5.4 GW)
to the first significant load center is about 1/4 wave
at 60 Hertz. Churchill Falls has three 735 kV lines to move
the energy; 1.8 GW per line. At 735 kV, that's about a
300 ohm load impedance. I've seen estimates that put power
line impedance between 100 and 400 ohms. So there might be
a match at full load, but at no load there is serious
mismatch. Of course the generator impedance is close
to zero (feedback achieves this) so there is no attempt
to match at that end. (The above quick analysis ignores
that it is actually a three phase system).

There are apparently serious challenges with keeping
the output voltage down on lightly loaded lines (q.v.
Ferranti effect).

And what happens when the load breakers at the end of
the line trip. 4 milliseconds later the reflected wave
arrives back at the plant. What happens when it hits
the 0 output impedance of the generators?
And how does one stop 11 columns of water 1000 feet
high (500 psi) and 20 feet in diameter before the
generators overspeed?

I am betting there is a story there.

...Keith

Standing morphing to travelling waves, and other stupid notions
 

On Jan 10, 9:23 pm, Jim Kelley wrote:
A standing wave is an amplitude vs position envelope.

Sorry, that is a false statement. Please reference "Fields and Waves
in Communication Electronics" by Ramo, Whinnery, and Van Duzer, page
343. The equation for the standing wave voltage is: Ez = Efor*e^j(wt-
Bz) + Eref*e^j(wt+Bz)

The equation for a standing wave *envelope* does not contain an
(omega*t) term. The equation for the *standing wave* indeed does
obviously contain (omega*t) terms since the equation for a standing
wave is the sum of the two component traveling waves each containing
an (omega*t) term.

If the (omega*t) term is omitted it is an envelope equation, not a
wave equation.
--
73, Cecil, w5dxp.com

Standing morphing to travelling waves, and other stupid notions
 

On Jan 10, 8:54 pm, Jim Kelley wrote:
Technically, they're just spatial interference patterns, so of course
they don't propagate energy. They're like any other spatial
interference pattern in that regard.

Thus Hecht's suggestion that they don't deserve to be called waves. I
think they should be called illusionary waves.
--
73, Cecil, w5dxp.com

Standing morphing to travelling waves. was r.r.a.a Laugh Riot!!!
 

On 9 Jan, 19:59, Cecil Moore wrote:
On Jan 9, 7:48 pm, art wrote:

Thus it is the length of the antenna by your statement is what turns
around the current regardless of the frequency applied.

The feedpoint impedance of these standing wave antennas can be closely
approximated by

Zfp = (Vfor+Vref)/(Ifor+Iref)

where all values are phasors. For instance, the reflected voltage will
be out of phase with the forward voltage at the feedpoint for a
resonant 1/2WL dipole while the reflected current will be in phase
with the forward current. The feedpoint impedance of a 1/2WL dipole is
very close to (|Vfor|-|Vref|)/(|Ifor|+|Iref|). See if you can figure
it out for other lengths of dipoles.
--
73, Cecil, w5dxp.com

We haven't moved forward a bit on that first sentence of the other
post
which is " what created the reflecting voltage" of this resonant
radiator
when it is a fractional wavelength or a electrically full wave length?
Since I am interested in a time varying current for propagation why
should I
worry about anything else ?
Art

Standing morphing to travelling waves, and other stupid notions
 

"AI4QJ" wrote in message
...
and add them together like Cecil does to get the total power? Boy, I'll
bet you'd have a *lot*!

I'm sorry but this taunt rings a little hollow...it just isn't funny
because you can/will get a finite number for power.


its called the Dirac delta function. and infinitely narrow, infinitely
high, single pulse that contains finite energy... the Fourier spectrum of it
includes frequencies from zero to infinity which extend in time from
negative infinity to positive infinity... the function that doesn't exist,
yet has influence across all time and has infinite numbers of uses when
analyzing circuits even though no one can generate it.

Standing morphing to travelling waves. was r.r.a.a Laugh Riot!!!
 

On Jan 10, 10:24 pm, Keith Dysart wrote:
The power factor correction
capacitors make the load impedance real, they do not match
the load to the impedance of the distribution line. As such,
they have not eliminated reflections.

It's a little more complicated than that. If the voltage and current
are actually brought into phase all along the transmission line, the
system is indeed a traveling wave system free of reflections. If the
power factor is exactly 1.0 at all points up and down the line, the
line is flat, i.e. matched by definition. Of course, it's not a
perfect system and the power factor is rarely exactly 1.0 so the
system usually exhibits signs of a mismatch, an overhead expense for
the power company.
--
73, Cecil, w5dxp.com

Standing morphing to travelling waves. was r.r.a.a Laugh Riot!!!
 

On Jan 10, 11:34 pm, art wrote:
We haven't moved forward a bit on that first sentence of the other
post which is " what created the reflecting voltage" of this resonant
radiator when it is a fractional wavelength or a electrically full wave length?

The characteristic impedance of the horizontal wire above ground is in
the neighborhood of 600 ohms. The "load" impedance at the end of the
wire can be considered to be infinite. The reflection coefficient at
the tip of a dipole is 1.0, i.e. all the forward voltage is reflected
in phase. This is true no matter what the length of the dipole. The
round trip delay that the forward wave makes can be used to get a fair
approximation of the feedpoint impedance using transmission line
equations and assigning an appropriate value to the alpha loss factor
which not only includes real losses but also "losses" due to
radiation.
--
73, Cecil, w5dxp.com

Standing morphing to travelling waves, and other stupid notions
 

On Jan 10, 11:45 pm, "AI4QJ" wrote:
But: The closer standing wave ratio of the illusionary is to 1:1, the closer
we are to antenna resonance so the illusion has more significance than, say
a mirage in the desert. ;-)

By "illusionary", I certainly didn't mean "imaginary". A magician's
act contains illusions based on real events. It's just that the
audience doesn't comprehend what is really happening. That's exactly
what is occurring here with standing waves. The standing waves, like
the magician's illusions, certainly have a real existence but many of
the conclusions about standing waves that are presented here are based
on the illusions created by those real standing waves (which do not
meet the definition for EM, i.e. photonic waves).
--
73, Cecil, w5dxp.com

Standing morphing to travelling waves. was r.r.a.a Laugh Riot!!!
 

On 11 Jan, 06:18, Cecil Moore wrote:
On Jan 10, 11:34 pm, art wrote:

We haven't moved forward a bit on that first sentence of the other
post which is " what created the reflecting voltage" of this resonant
radiator when it is a fractional wavelength or a electrically full wave length?

The characteristic impedance of the horizontal wire above ground is in
the neighborhood of 600 ohms. The "load" impedance at the end of the
wire can be considered to be infinite. The reflection coefficient at
the tip of a dipole is 1.0, i.e. all the forward voltage is reflected
in phase. This is true no matter what the length of the dipole. The
round trip delay that the forward wave makes can be used to get a fair
approximation of the feedpoint impedance using transmission line
equations and assigning an appropriate value to the alpha loss factor
which not only includes real losses but also "losses" due to
radiation.
--
73, Cecil, w5dxp.com

Thanks for the reply Cecil which has opened my eyes regarding the
trend of your thoughts.
Try to change your thinking to the following. An alternating current
is created by a generator
that moves in a circular fashion. The + and _ functions are a
mathematical tool obtained by the sine .cosine etc. This is a measure
ONLY of the amplitide only at a particular point in time. If you put a
scope on it you will see a wave like function only because your eyes
e.t.c.
is not fast enough to take more samples at the point in question. Thus
it is an illusion to think of forward travel. Another way of looking
at it is to stand in the center of a football field and watch the
spectators stand up in sequence. At any point of what you are viewing
you /
your eye mechanism,are seing a movement upwards at a single position
at a single point in time.
At no time is there anything moving forward thus this reflection of
yours cannot occur.
I think we can end out interchange at this point
Very best regards
Art Unwin KB9MZ....xg(uk)

Standing morphing to travelling waves, and other stupid notions
 

Cecil Moore wrote:
On Jan 9, 11:22 pm, Roy Lewallen wrote:
Just what is a "wave", anyway? Are there different "kinds" of
electromagnetic wave?

Take a look at the E-field, H-field, and direction of travel for an EM
(photonic) wave. An RF standing wave does not behave like an EM wave
nor does it meet the definition of an EM wave which can be represented
by a Poynting vector. The Poynting vector for an RF standing wave has
a magnitude of zero and no direction.
--
73, Cecil, w5dxp.com

Cecil,

That is flat out wrong. For a plane wave the E and H fields are
perpendicular for either traveling waves or standing waves. For a
coaxial cable operating in the normal TEM mode, the E field is radial
and the H field is circular around the center conductor. Again, the E
field and H field are always perpendicular. Unless one or both of the
fields are exactly zero, the Poynting vector will be nonzero. It will
have a magnitude and direction.

I suppose what you are looking at is some sort of time average. In that
case the average of the Poynting vector at a single point in space may
be different for standing waves and traveling waves. However, that
information is essentially useless. The only thing with physical
reality, related to Poynting vectors, is the integral of the Poynting
vector over a closed surface. Equivalently, the only thing with physical
reality is the divergence of the Poynting vector.

In the lossless cases we are typically discussing, the time-averaged
integral or the divergence is exactly zero for either the traveling wave
case or the standing wave case. The Poynting vector is no help in making
any sort of distinction at all.

73,
Gene
W4SZ

Standing morphing to travelling waves, and other stupid notions
 

Cecil Moore wrote:
On Jan 10, 10:59 am, Gene Fuller wrote:
. It is really amazing that you can make up so many requirements that
are
completely unknown to the rest of the world. Is that a Mensa thing?

Methinks you need to study and comprehend the nature of photons and
photonic waves.
--
73, Cecil, w5dxp.com

Cecil,

I have been doing that for decades. Is there some tutorial material I
seemed to have overlooked? (other than RRAA, of course) I already have
tons of books on physics, engineering, and optics.

What do you recommend as the definitive reference on "the nature of
photons and photonic waves"?

73,
Gene
W4SZ

Standing morphing to travelling waves. was r.r.a.a Laugh Riot!!!
 

Cecil Moore wrote:
On Jan 10, 10:55 am, Gene Fuller wrote:
. You never give up, do you? Even when you are caught in an utter
lie. You
know exactly what the capacitors are for, and it isn't to control
transmission line reflections from open ends of the line.

I'm sorry, Gene, but I cannot alleviate your ignorance with one
posting. Given a voltage phasor and a current phasor with a phase
angle between them, there is absolutely no way to distinguish between
a mismatch and a reflection. The purpose of those power factor
capacitors on the power line poles is to turn those transmission lines
into money-making traveling wave delivery systems rather than allow
money-losing standing wave systems. Please stop your emoting long
enough to realize what I have said is true.

If the capacitors were not there, the inductive loads would cause
reflections just as they do on an RF transmission line. The only
difference is that the 60 Hz transmission line is a small fraction of
a wavelength. If you scaled the 60 Hz system to 6 MHz, all the same
laws of physics would apply and the similarities would be readily
apparent.
--
73, Cecil, w5dxp.com

Cecil,

I am glad to see you have now acknowledged the real purpose of the
capacitors. You avoided a direct response to my comment, of course, but
progress is being made.

8-)

73,
Gene
W4SZ

Standing morphing to travelling waves. was r.r.a.a LaughRiot!!!
 

Gene Fuller wrote:
"You know exactly what capacitors are for, and it isn`t to control
transmission line reflections from open ends of the line."

When you open a circuit at an instant when current is flowing, the
transient created can be large. Natural phenomena also create injurious
spikes on a power line. Capacitors absorb transient current reducing and
delaying a voltage rise which gives overvoltage protection a chance to
operate.

Lightly loaded induction motors cause power factor to lag, demanding
additional current. Capacitors to correct large amounts of lagging
current often take the form of over-excited unloaded induction machines
(rotory capacitors) which produce an offsetting leading power factor.

Power loss in power lines is proportional to the square of the current,
whatever the cause, so power factor correction aims at to reduce current
in the line.

Best regards, Richard Harrison, Kb5WZI

Standing morphing to travelling waves, and other stupid notions
 

Cecil Moore wrote:

On Jan 10, 9:23 pm, Jim Kelley wrote:

A standing wave is an amplitude vs position envelope.


Sorry, that is a false statement.

No, in the most general sense, it is a precisely accurate statement.

Please reference "Fields and Waves
in Communication Electronics" by Ramo, Whinnery, and Van Duzer, page
343.

Ah. Apparently the only book you know of that contains the
description of a standing wave.

The equation for the standing wave voltage is: Ez = Efor*e^j(wt-
Bz) + Eref*e^j(wt+Bz)

You must belong to the Standing Wave Equation of the Week Club. Nice
letter choices. :-)

The equation for a standing wave *envelope* does not contain an
(omega*t) term.

That right. As I said, it is a function of amplitude vs postion.

The equation for the *standing wave* indeed does
obviously contain (omega*t) terms since the equation for a standing
wave is the sum of the two component traveling waves each containing
an (omega*t) term.

And when Ramo and Whinnery, for example, plots standing wave current
on a vertical radiator, for example, why do you suppose it looks like
an amplitude vs. position curve?

If the (omega*t) term is omitted it is an envelope equation, not a
wave equation.

Ah. So according to Cecil, we have a new definition for a wave which
now stipulates that it must only be expressed as a function of time.

If you only knew how ridiculous you sound.

ac6xg

Standing morphing to travelling waves, and other stupid notions
 

On Jan 11, 12:10 pm, Gene Fuller wrote:
What do you recommend as the definitive reference on "the nature of
photons and photonic waves"?

I personally like "Optics" by Hecht and his idea that standing waves
maybe shouldn't be called waves at all. EM waves move energy and
conserve momentum. Standing waves don't.
--
73, Cecil, w5dxp.com

Standing morphing to travelling waves. was r.r.a.a Laugh Riot!!!
 

art wrote
Thanks for the reply Cecil which has opened my eyes regarding the
trend of your thoughts.
Try to change your thinking to the following.

big snip

At no time is there anything moving forward thus this reflection of
yours cannot occur.
I think we can end out interchange at this point
Very best regards
Art Unwin KB9MZ....xg(uk)

Now this is gonna be a hoot, watching Art and Cecil exchange
technical repartees.

Mike W5CHR