Cecil Moore wrote:
John Popelish wrote:

When you talk about current flowing, you seem to be thinking of
current waves traveling along a conductor. Others seem to be saying
"current" and thinking of charge movement. I think that only the
second is technically correct ...


John, many thanks for some rationality from a cool head.

Conventions aside, that sounds about right. So would you agree
that if there's a forward current of one amp

By this I assume you mean a traveling current wave with an RMS value
of 1 amp.

and a reflected current of one amp,

Meaning a returning current wave with an RMS current of 1 amp.

the net charge movement is zero and therefore
the standing wave current is not "going" anywhere?

Sorry, no. There is no net (average over one cycle) current, whether
the wave is traveling or standing. In both cases the instantaneous
current changes direction every half cycle at any given point. If
there is a standing wave made of a 1 ampere RMS current wave and a 1
ampere RMS returning wave, then the standing wave current will vary
from zero amperes RMS at current nodes to 2 amperes RMS at current
peaks. Looking just at just current, and at only a single point, a
traveling current wave and a standing current wave are
indistinguishable. You cannot tell if the measured RMS current is
made up of a wave traveling in one direction, or the sum of two waves
traveling in opposite directions.

How can something with a constant fixed phase angle of zero degrees "go" anywhere?

The only way to understand a standing wave having a phase of zero
degrees, that makes sense to me, is that it applies to all points
between one current node and the next. The points between the next
two nodes have a phase of 180 degrees (charge is moving in the
opposite direction at all times) with respect to the points between
the first two nodes. So, if you pick some point between a pair of
current nodes, all other points along the standing wave must be either
be in phase with the current at that point, or 180 degrees out of
phase with it. In a standing wave, charge sloshes back and forth in
opposite directions between alternate pairs of current nodes.
Likewise, where the charge piles up and sinks (at the current nodes),
voltage peaks occur because of the charge accumulation or shortage.

Standing waves involve no net wave travel in either direction, though
anywhere except at the current nodes, charge is certainly moving back
and forth along the conductor, during a cycle.


That's unclear to me. Why can't the E-field and H-field simply be
exchanging energy at a point rather than any net charge moving
laterally?

In an isolated EM plane wave, I think this is the case, and
displacement charge in space takes the place of conductor current.
But when a wave is guided by a conductor, we can measure the charge
sloshing back and forth in the conductor in response to those fields.

Take a look at:
http://galileo.phys.virginia.edu/cla...axwell_Eq.html
about half way down.

Here is an excerpt:

(begin excerpt)

"Displacement Current"

Maxwell referred to the second term on the right hand side, the
changing electric field term, as the "displacement current". This was
an analogy with a dielectric material. If a dielectric material is
placed in an electric field, the molecules are distorted, their
positive charges moving slightly to the right, say, the negative
charges slightly to the left. Now consider what happens to a
dielectric in an increasing electric field. The positive charges will
be displaced to the right by a continuously increasing distance, so,
as long as the electric field is increasing in strength, these charges
are moving: there is actually a displacement current. (Meanwhile, the
negative charges are moving the other way, but that is a current in
the same direction, so adds to the effect of the positive charges’
motion.) Maxwell’s picture of the vacuum, the aether, was that it too
had dielectric properties somehow, so he pictured a similar motion of
charge in the vacuum to that we have just described in the dielectric.
This is why the changing electric field term is often called the
"displacement current", and in Ampere’s law (generalized) is just
added to the real current, to give Maxwell’s fourth -- and final --
equation.

(end excerpt)

Cecil,

Earlier you made comments about the time delay through a 75 meter
loading inductor being somewhere around 60 nS or so.

You have consistently disagreed with me when I said time delay through
an inductor with tight mutual coupling from turn-to-turn is somewhat
close to light speed over the physical length of the inductor, rather
than the time it takes current to wind its way around through the
copper. You didn't like my measurement of a small 100uH choke, and said
a large inductor like a bug catcher coil is different. You predicted
standing waves in that inductor.

I have a 100 turn 2 inch diameter air wound inductor of pretty good
quality. It is 10 inches long.

Please tell all of us the time delay you expect in that inductor on 3.8
MHz. Please tell all of us what that delay means for your various
changing theories about waves standing in that coil.

I'll sweep the inductor from below the BC band up to 30MHz in a time
measurement mode and post the printout of the sweep with scale values
and markers that show time delays.

73 Tom

Cecil warned me that if I posted, the posting would be nit picked to
pieces. I`ve read correct postings describing the incident and reflected
waves on a transmission line, and Maxwell`s secret of radiation
(displacement current produces a magnetic field same as conduction
current). All this may be relevant or not to some extent, but they don`t
seem to resolve the current through a coil.

Tom, W8JI wrote:
"You have consistently disagreed with me when I said the time delay
through an inductor with tight mutual coupling from turn to turn is
somewhat close to light speed over the physical length of the inductor,
rather than the time it rakes to wind its way around the copper."

That contradicts established experience.

The property of reactance is to limit current flow. Inductive reactance
limits by means of counter-emf which depends upon the rate at which
current is changing in the coil. A-C current changes most rapidly at
zero time (the axis crossings of the sine waveform). Lenz`s law says the
counter-emf must oppose the growth of current in this case. Opposotion
of the counter-emf causes the current to reach its maximum 1/4-cycle
after the emf applied to the coil reaches its maximum. As almost
everyone knows, the current lags by 90-degrees in a pure inductor. Make
the turns coupling as tight as you can, the current is still delayed by
90-degrees.

Now, it surely is possible to bypass a perfect inductor with a capacitor
to mitigate a delay.

I can`t repeat without retyping text on my screen, so the fact that I
don`t retype everything only means I`m lazy.

Right or wrong, W8JI may never lose an argument, but when he is clearly
wrong it should be pointed out.

Best regards, Richard Harrison, KB5WZI

Richard Harrison wrote:

Tom, W8JI wrote:
"You have consistently disagreed with me when I said the time delay
through an inductor with tight mutual coupling from turn to turn is
somewhat close to light speed over the physical length of the inductor,
rather than the time it rakes to wind its way around the copper."

That contradicts established experience.

Tom seems to be confusing the effects of the E-field with the
effects of the H-field. The E-field propagates at the speed
of light through a coil. The H-field propagates at the
speed of light through a capacitor.

Make
the turns coupling as tight as you can, the current is still delayed by
90-degrees.

Can the actual current phase delay be estimated knowing the Q
of the coil? I don't recall a formula for that.

Now, it surely is possible to bypass a perfect inductor with a capacitor
to mitigate a delay.

Dang Richard, now you've told Tom how to run his experiment
in order to obtain the results he predicts. :-)
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:
Now, it surely is possible to bypass a perfect inductor with a capacitor
to mitigate a delay.

Dang Richard, now you've told Tom how to run his experiment
in order to obtain the results he predicts. :-)

You say you will accept something, you ask for something to be done,
and when it is offered you back up and stall, preparing advance excuses
why it won't be done correctly and refusing to make a prediction.

You've eaten up hours of my time and the only thing I've learned is you
don't want to learn, and you are so unsure of yourself you'll avoid any
prediction of how something will work any way you can.

I'm just amazed you have to fall back on name calling, mubo-jumbo, and
inuendo when someone offers to help you understand something. I'm all
done with this too.

73 Tom

wrote:
Cecil Moore wrote:
Now, it surely is possible to bypass a perfect inductor with a capacitor
to mitigate a delay.
Dang Richard, now you've told Tom how to run his experiment
in order to obtain the results he predicts. :-)

You say you will accept something, you ask for something to be done,
and when it is offered you back up and stall, preparing advance excuses
why it won't be done correctly and refusing to make a prediction.

You've eaten up hours of my time and the only thing I've learned is you
don't want to learn, and you are so unsure of yourself you'll avoid any
prediction of how something will work any way you can.

I'm just amazed you have to fall back on name calling, mubo-jumbo, and
inuendo when someone offers to help you understand something. I'm all
done with this too.

That's exactly what he did back in November 2003. I see he hasn't
changed any. Wonder who the next person will be to get sucked in, jerked
around, and disgusted.

Roy Lewallen, W7EL

Roy Lewallen wrote:
That's exactly what he did back in November 2003. I see he hasn't
changed any. Wonder who the next person will be to get sucked in, jerked
around, and disgusted.

Here comes the junk yard dog guru gang. Tom has refused
to give me the necessary needed information about his
coil and his measurement configuration and you are blaming
me for that? With the information that he has provided
so far, I might as well be trying to guess how much
loose change he has in his pocket.
--
73, Cecil http://www.qsl.net/w5dxp

wrote:
Cecil Moore wrote:
Dang Richard, now you've told Tom how to run his experiment
in order to obtain the results he predicts. :-)

You say you will accept something, you ask for something to be done,
and when it is offered you back up and stall, preparing advance excuses
why it won't be done correctly and refusing to make a prediction.

It was a joke, Tom. I am still trying to work out the measurement
details in my mind. It certainly won't do any good to measure
a parameter other than the one we want to measure.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:

wrote:
You say you will accept something, you ask for something to be done,
and when it is offered you back up and stall, preparing advance excuses
why it won't be done correctly and refusing to make a prediction.

I'm not stalling, Tom, I'm waiting for you to provide the
information I requested. Why are you avoiding providing
that information? It's pretty simple stuff that anyone
would need to make a prediction.

1. What is the inductance of the coil? What is the
Q of the coil?

2. What kind of current probes are you using with your
Network Analyzer? What are the characteristics of the
driving source signal?

3. What is the schematic configuration of your test setup?
How can I possibly make a prediction without that schematic?

That is certainly a reasonable request. Without that
information, a prediction is impossible, not just for
me but for anyone else.
--
73, Cecil http://www.qsl.net/w5dxp

wrote:

You say you will accept something, you ask for something to be done,
and when it is offered you back up and stall, preparing advance excuses
why it won't be done correctly and refusing to make a prediction.

You've eaten up hours of my time and the only thing I've learned is you
don't want to learn, and you are so unsure of yourself you'll avoid any
prediction of how something will work any way you can.

I'm just amazed you have to fall back on name calling, mubo-jumbo, and
inuendo when someone offers to help you understand something. I'm all
done with this too.

Dang! I was looking forward to your test results, and a description
of your test method. I think your 2" diameter coil is a good example
of an inductor that is neither a perfect "lump" nor a pure
transmission line.