Cecil Moore wrote:
John Popelish wrote:

From an earlier posting: For example, if we took a snapshot of the
current, all along the line at the moment it peaked it might look like
thislength of arrow represents current magnitude, and head shows
direction)(view in fixed width font)


....--- --- -- - - -- --- --- -- - - --......
hole-------------------50 ohm coax-------------------hole

x y
There is a standing wave current node at 'x' and a standing
wave current antinode (loop maximum) at 'y'. Let's say we
installed coils at those two points

....--- --- -- - - -- --- --- -- - - --......
hole--------------/////----50 ohm coax----/////------hole
x y
Now we have current flowing into both ends of the coil
located at 'x' and current flowing out of both ends of
the coil at 'y'. How does the lumped circuit model handle
that situation?

If we assume the coil is an idealized lumped inductance with no stray
capacitance at all (not a real inductor) then it would have the same
instantaneous current at each end and that current would be zero,
since it has zero size. In other words it would fit entirely in the
point that holds the node.

Real inductors with stray capacitance and imperfect magnetic coupling
for all parts of its internal current path, would have a phase shift
in the current at opposite ends, so they would have current at their
ends that was 180 degrees out of phase, if they were centered on the
node points. For half of each cycle, current would be entering each
end, and for the other half of each cycle, current would be leaving
each end. Both those currents would detour out the sides f the
inductor into displacement current through the stray capacitance of
the surface of the inductor to its surroundings.

I think (with very little actual knowledge of the software) this
conceptual model is how EZNEC handles current through a modeled
inductor and how it can have different currents at the inductor ends,
without being aware of whether those currents are driven by traveling
or standing waves. It is all based on current through inductor
segments and voltage across capacitive segments. If the segments are
small enough, it is a good approximation of a distributed solution.

Continuing with this posting:

Please don't be silly. Distributed networks have points. An infinite
number of them. Calculus is used to smoothly move through this
infinity of points. But at any particular point, current is defined
as the rate of movement of charge past that point.


No argument, but that is instantaneous current and that is NOT
the subject of this discussion. We are discussing the RMS phasor
value of current used by W8JI and W7EL for their measurements
and reported by EZNEC as in the graphic at:

I am not arguing this point. RMS values capture the amplitude of a
cycle of variation. I am inside the cycle. But the two views are
consistent.

http://www.qsl.net/w5dxp/travstnd.GIF

Please look at the standing wave current phase and tell us how
that flat phase curve can be used to measure the phase shift
in a wire or coil.

The current reported by EZNEC and measured by W8JI and W7EL is
*NOT* instantaneous current. It is RMS current. Instantaneous
current is completely irrelevant to this discussion.

I am not arguing for the validity of that measurement. Argue about it
with someone who is.

I've been waiting for that to happen. There's no point
continuing an argument with someone who denies one of
the cornerstones of EM wave theory.


So you deny that there are any points (where voltage can be defined or
that charge passes) in all distributed networks?
How strange.


:-) You have your points confused. I was talking about a logical
point. Here, let me translate for you. There's no *reason* to
continue an argument with someone who denies one of the
cornerstones of EM wave theory. John, is English your native
language? For the record, I did NOT deny the existence any
physical points!!!

The fact remains that standing wave current phase cannot
be used to measure phase delay through a wire or through
a coil. There is no phase information in standing wave
current phase.


Yes. That fact remains.
It is a non sequitur in the above discussion, however.


Whoa there, John, it is the entire reason for this discussion.

According to you, you are finished talking about coils, and want to
delve strictly into wave concepts. To honor your request, I have
tried to keep the discussion general, and avoid bringing up the effect
on and measurements of coils. But, in this post, you talk about
almost nothing else but coils. I get the distinct feeling that you
want to win a debate far more than you want to reach an understanding
with no internal contradictions. And you are willing to use dishonest
debate tactics (like telling me not to discuss a topic with you, and
then telling me that that exact topic is "the entire reason for this
discussion". Do you get beat up a lot in face-to-face arguments?

W7EL used that standing wave current phase to try to measure
phase shift through a coil. If there is no phase information
in standing wave current phase, then his entire argument
falls apart and he is back to square one with his flawed
lumped circuit model.

Yes. But I cannot concede that point of discussion for someone else.
Are you going to hit me over the head with this till every person in
the World agrees with you? I am trying to think the general case
through with you.

In case you don't realize, there is more than one person out here,
responding to you.

You remind me of a type of insanity where the sufferer thinks that
everything he is experiencing an organized illusion by a single
offending intelligence (you against the Matrix) bent on forcing him to
think that a lie is the truth, regardless of who or what he deals
with. Everyone he meets, every apparently random happenstance, the
actions of his dog and the weather, generally, are all a conspiracy to
force him to think that black is white, and he isn't going to fall for it.

If you cannot carry on a conversation with more than one person at a
time, and treat each of them as a separate mind, then this is the
wrong venue for you.

John Popelish wrote:
If we assume the coil is an idealized lumped inductance with no stray
capacitance at all (not a real inductor) then it would have the same
instantaneous current at each end and that current would be zero, since
it has zero size. In other words it would fit entirely in the point
that holds the node.

And such a coil is impossible in the real world so why even mention it?
I want to hear about real world one foot long, 100 uH coils.

Real inductors with stray capacitance and imperfect magnetic coupling
for all parts of its internal current path, would have a phase shift in
the current at opposite ends, so they would have current at their ends
that was 180 degrees out of phase, if they were centered on the node
points.

Yes, now please tell that to W8JI and W7EL. They are not listening
to me.

I am not arguing for the validity of that measurement. Argue about it
with someone who is.

That's my entire argument at the moment and W7EL is avoiding that
argument like a plague.

In case you don't realize, there is more than one person out here,
responding to you.

Please forgive me for not recognizing which of the ten individual
junk yard dog "experts" is biting my ankles at any particular time. :-)

You remind me of a type of insanity where the sufferer thinks that
everything he is experiencing an organized illusion by a single
offending intelligence (you against the Matrix) bent on forcing him to
think that a lie is the truth, regardless of who or what he deals with.
Everyone he meets, every apparently random happenstance, the actions of
his dog and the weather, generally, are all a conspiracy to force him to
think that black is white, and he isn't going to fall for it.

IMHO, hardly anyone here on r.r.a.a is interested in technical facts.
Most "experts" think they already know everything, wouldn't recognize
a differing concept if it bit them in the arse, and are more dedicated
to preserving the pecking order than anything else. 'Course, I am only
human and could, therefore, unlike the omniscient experts, be wrong
about that.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:
John Popelish wrote:

If we assume the coil is an idealized lumped inductance with no stray
capacitance at all (not a real inductor) then it would have the same
instantaneous current at each end and that current would be zero,
since it has zero size. In other words it would fit entirely in the
point that holds the node.


And such a coil is impossible in the real world so why even mention it?

Because it is the limiting case of the possible. Understanding why it
is the limit interests me.

I want to hear about real world one foot long, 100 uH coils.

Then you have changed your mind from a few days ago.
No problem for me.

Real inductors with stray capacitance and imperfect magnetic coupling
for all parts of its internal current path, would have a phase shift
in the current at opposite ends, so they would have current at their
ends that was 180 degrees out of phase, if they were centered on the
node points.


Yes, now please tell that to W8JI and W7EL. They are not listening
to me.

I just did. I hope you realize that anyone is perfectly free to
ignore anything posted to this or any other newsgroup, and long as it
pleases them. If you are going to have trouble sleeping because you
can't get complete agreement from everyone who you have ever seen post
to this group, your problems are a lot bigger than coils and waves.

I am not arguing for the validity of that measurement. Argue about it
with someone who is.

That's my entire argument at the moment and W7EL is avoiding that
argument like a plague.

That is their prerogative. Deal with it. I am putting considerable
effort to understand the physics of the situation and to share my
thoughts with you. If this is no interest to you, I will discuss this
interesting topic with someone else.

In case you don't realize, there is more than one person out here,
responding to you.

Please forgive me for not recognizing which of the ten individual
junk yard dog "experts" is biting my ankles at any particular time. :-)

I am insulted that you include me in that derogatory characterization.
I have been polite, patient and respectful with you in this
discussion.

You remind me of a type of insanity where the sufferer thinks that
everything he is experiencing an organized illusion by a single
offending intelligence (you against the Matrix) bent on forcing him to
think that a lie is the truth, regardless of who or what he deals
with. Everyone he meets, every apparently random happenstance, the
actions of his dog and the weather, generally, are all a conspiracy to
force him to think that black is white, and he isn't going to fall for
it.

IMHO, hardly anyone here on r.r.a.a is interested in technical facts.
Most "experts" think they already know everything, wouldn't recognize
a differing concept if it bit them in the arse, and are more dedicated
to preserving the pecking order than anything else. 'Course, I am only
human and could, therefore, unlike the omniscient experts, be wrong
about that.

And that is exactly why I have refrained from personal attacks (though
I have indulged in a few observations as above, because I think
considering them might open your eyes to how you appear to others, and
how that interferes with your arguments. So even those observations
were not made in an attempt to win an argument with you, but to assist
you in thinking more clearly.

For the most part, I have tried to talk about physics, not pecking
order or personalities. But you keep cutting me off, saying you are
not interested in physics, but in winning a debate with a few people,
regardless of who you have to insult to win.

At this point, my mental model of how your mind works is just about as
interesting to me as my mental model of how EM waves work. The
universe is full of strange and fascinating processes. But if you get
back to physics, I will soon lose interest in your mind.

John Popelish wrote:
Please forgive me for not recognizing which of the ten individual
junk yard dog "experts" is biting my ankles at any particular time. :-)

I am insulted that you include me in that derogatory characterization.
I have been polite, patient and respectful with you in this discussion.

It wasn't derogatory, John. It was a paraphrasing of the old saying:
"When one is up to one's ass in alligators, it's hard to remember
that the original purpose was to drain the swamp."

But if you get back to physics, I will soon lose interest in your mind.

I have no idea if "losing interest" is a good thing or a bad thing.
--
73, Cecil http://www.qsl.net/w5dxp

John Popelish wrote:

If we assume the coil is an idealized lumped inductance with no stray
capacitance at all (not a real inductor) then it would have the same
instantaneous current at each end and that current would be zero, since
it has zero size. In other words it would fit entirely in the point
that holds the node.

Real inductors with stray capacitance and imperfect magnetic coupling
for all parts of its internal current path, would have a phase shift in
the current at opposite ends, so they would have current at their ends
that was 180 degrees out of phase, if they were centered on the node
points. For half of each cycle, current would be entering each end, and
for the other half of each cycle, current would be leaving each end.
Both those currents would detour out the sides f the inductor into
displacement current through the stray capacitance of the surface of the
inductor to its surroundings.

I think (with very little actual knowledge of the software) this
conceptual model is how EZNEC handles current through a modeled inductor
and how it can have different currents at the inductor ends, without
being aware of whether those currents are driven by traveling or
standing waves. It is all based on current through inductor segments
and voltage across capacitive segments. If the segments are small
enough, it is a good approximation of a distributed solution.

There are two ways of modeling an inductor in EZNEC. One is by using an
inductive "load". This is a pure lumped inductance, which takes up zero
physical space and whose currents are equal at its two terminals. It
does not couple or react at all to its surroundings other than via its
terminals, and its voltage-current characteristics are dictated by that
of a pure inductance, v = L di/dt. For a number of reasons discussed
many times here, this isn't a good model for many or most typical
loading coils.

The other way of modeling an inductor in EZNEC is by making it from
conductors -- "wires" -- arranged in a polygonal helix. (EZNEC v. 4.0
provides an automated way to generate this structure.) These wires are
treated exactly the same as all other wires in the model. As long as the
turns aren't too close together (conservatively, closer than several
wire diameters, but in practice good results are usually obtained with
spacing as close as one diameter air space between wires), it does a
very good job of calculating the inductor currents and radiation. (It's
a little generous about loss if the turns are close because it doesn't
account for proximity effect.)

EZNEC calculates the total current by first calculating the self and
mutual impedances of every segment in the model from a fundamental
equation, then using Ohm's law to find the total current in each segment
from those impedances and the voltages from the user specified
sources.(*) It's not aware of traveling or standing waves. The presence
or absence of standing waves -- that is, a changing magnitude of current
with position -- can be seen by viewing its output. Displacement current
is a consequence of mutual coupling between segments -- in a dipole, the
dominant coupling is to the other half of the dipole, and in a grounded
monopole, to ground. However, each segment couples to every other, even
on its own wire, and it's this coupling which brings about the current
distribution that ultimately occurs.

EZNEC deals only with total currents and makes no effort to detect, use,
or break up total current into individual traveling waves. It isn't
aware of whether currents are "driven by traveling or standing waves" if
for no other reason that no currents are ever "driven by" traveling or
standing waves. Voltage differences cause currents which can be
described as traveling waves. When multiple traveling waves are summed
to find a total current, the amplitude of the sinusoidal current varies
with position along the line, and this envelope is called a "standing
wave". A standing wave is simply a description of the magnitude
distribution of the total current along a wire or transmission line. It
doesn't drive or cause anything -- it's a description of an effect, not
a cause. All the fuss about standing waves is a diversion which confuses
the issue and deflects attention from the salient issues involved in
understanding the topic under discussion.

(*) This is a simplified explanation. For details, see Part I of the
NEC-2 manual.

Roy Lewallen, W7EL

Roy Lewallen wrote:
EZNEC deals only with total currents and makes no effort to detect, use,
or break up total current into individual traveling waves.

Then, without effort, EZNEC accurately reports the presence
of traveling waves or standing waves as can be seen from
the graph of the EZNEC results at:

http://www.qsl.net/w5dxp/travstnd.GIF

The graph on the left is for traveling wave current. Its
magnitude is fixed and its phase varies with wire length.
Traveling wave phase can be used to determine the phase
shift through the wire (or through a coil).

The graph on the right is for standing wave current. Its
phase is fixed and its magnitude varies with wire length.
Standing wave magnitude can be used to determine the phase
shift through the wire (or through a coil) by taking the
arc-cosine of the magnitude.
--
73, Cecil http://www.qsl.net/w5dxp