Current through coils
 

wrote:

Cecil Moore wrote:
If you are technically correct, why are you so technically
silent on the subject?

I'm not silent.

You are silent on the subject of how the lumped-circuit model
explains more current at the top of the coil than exists at
the bottom of the coil. Please share that knowledge with us.

I think I've done a good job of explaining things, and I've made
measurements and posted results.

Have you made measurements with 1/4WL added to the top of
a mobile antenna? Will you believe your measurements when
you measure more current "flowing" into the bottom of the
coil than out of the top of the coil?

At least a dozen of my technical questions have gone
unanswered by being ignored. Lot's of readers have
noticed and commented in emails to me.

So what?

:-)

1.) I told you weeks ago I'm too busy working right now to get deeply
involved in this.

:-)

2.) When measurements are made, you dismiss them as "measuring current
in a system with standing waves".

It has been proven beyond a reasonable doubt that standing wave
current, func(kx)*func(wt) is not like traveling wave current,
func(kx +/- wt). Since standing wave current phase is devoid of
phase information, its phase cannot be used to determine the phase
shift through a coil. Standing wave current phase is what W7EL
measured. He drew conclusions about phase from measuring the
phase of a signal devoid of any phase information. I pointed
that technical fact out to him at the time and he ignored me.
I also pointed out that the phase information was actually
embedded in the amplitude measurement as a variation of a
cosine function. He rejected that assertion with a personal
remark.

If you will repeat your measurements with 1/4WL added
to the top of the base-loaded mobile antenna, you will
start to understand the physics involved. The current
taper through a coil depends upon where in the standing
wave environment that the coil is installed.

Then why can I measure a fixed inductor location in a dfixed antenna,
and range from no taper at all in current to just under 1/3 reduction
in current? Does you standing wave model explain this very repeatable
measurement?

Of course! If you measure the current taper at a point where the
standing wave current slope is near zero, you will measure near
zero taper. If you measure the current taper at a point where
the standing wave current slope is near maximum, you will measure
lots of taper. If you measure at just the right point, you will
measure current flowing into both ends of the coil at the same
time. That's another thing I have asked you to explain with no
response.

The lumped-circuit analysis fails for the typical
75m amateur radio mobile antenna.

I disagree. Unless we want to say so does the standing wave model.

The "standing wave model" is a component of the distributed-network
model which is known to work in the presence of standing waves. The
lumped-circuit model is known to fail in the presence of standing
waves. Quoting Dr. Corum: "There are no standing waves on a lumped
element circuit component. (In fact, lumped-element circuit theory
inherently employs the cosmological presupposition that the speed
of light is infinite, as every EE sophmore should know. See, e.g., -
"Electric Circuits", by J.W.Nilsson, Addison-Wesley, 1983, p. 3."

Dr. Corum's first sentence above means: *There are no standing waves
*allowed* in a lumped element circuit model.*

The antenna can be modelled as a series of lumped inductors with
capacitance to the outside world just as well as any other method.

But that is not what you and W7EL have done. You have modelled it
as a single coil with distributed capacitance. That approach is
known to fail when the coil is longer than 15 degrees and installed
in a standing wave environment.

If you use enough lumped inductors and capacitors, you have the
distributed network model but with a lot more math to do.
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

Hi Tom,

You may be shocked to discover this, but it is possible that my comments
have been reproduced slightly out of context.

At the time, Cecil was still clinging to the notion that if someone did
the measurements properly they could elicit the original phase
information contained in the traveling wave components. In particular,
the space and time coupling represented by the traveling wave function,
cos (kz - wt), was merely hiding. He has since changed his mind, and
unfortunately I seem to have become one of his quotable gurus on this topic.

A major part of the ongoing debate is the careless use of "phase" as if
it has a single definition. I have counted at least five different uses
in this thread, all correct in their own way, and none interchangeable.

I won't try to explain further. My level of understanding of phase and
such matters is fully satisfactory for me.

73,
Gene
W4SZ

Tom Donaly wrote:
Cecil Moore wrote:


Gene is 100% correct and we all should be grateful for that posting.

Neither you nor Roy have ever made a valid measurement of the
delay through a coil. It is admittedly a difficult measurement
to make directly. Ramo and Whinnery say it "is usually of
prohibitive difficulty".


I think that if Gene believes that, he should redo his math.
73,
Tom Donaly, KA6RUH

Current through coils
 

Gene Fuller wrote:
At the time, Cecil was still clinging to the notion that if someone did
the measurements properly they could elicit the original phase
information contained in the traveling wave components.

Sorry, Gene, you misunderstood what I was saying. That's why you
accidentally posted technical information that supported my side
of the argument without realizing it at the time. (Remember, I said
you were a genius for posting it and I thank you.)

What I previously said was: If the reflected wave could be eliminated,
as in a traveling wave antenna (like a terminated Rhombic) then
we could measure the actual delay through a loading coil using
the forward traveling wave, the only wave left in the system.

Here's one leg of a terminated Rhombic:

source-------------////////------------------load
coil

When I said the delay through a coil could be measured using a
traveling wave, this is what I had in mind.
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

Cecil,

Sorry, I am not telepathic. I merely accepted you at your written word,
which appears to be of little worth.


73,
Gene
W4SZ

Cecil Moore wrote:
Gene Fuller wrote:

At the time, Cecil was still clinging to the notion that if someone
did the measurements properly they could elicit the original phase
information contained in the traveling wave components.


Sorry, Gene, you misunderstood what I was saying. That's why you
accidentally posted technical information that supported my side
of the argument without realizing it at the time. (Remember, I said
you were a genius for posting it and I thank you.)

What I previously said was: If the reflected wave could be eliminated,
as in a traveling wave antenna (like a terminated Rhombic) then
we could measure the actual delay through a loading coil using
the forward traveling wave, the only wave left in the system.

Here's one leg of a terminated Rhombic:

source-------------////////------------------load
coil

When I said the delay through a coil could be measured using a
traveling wave, this is what I had in mind.

Current through coils
 

Gene Fuller wrote:
Sorry, I am not telepathic. I merely accepted you at your written word,
which appears to be of little worth.

I am often thinking faster than I can type and wind up not
expressing myself very well. This time, your misunderstanding
worked out to my advantage because it prompted you to post
some technical facts in rebuttal to what you assumed I said.
Your and Tom Donaly's technical facts were instrumental in
getting my point across and I thank you both for that. You
two seem to be the only ones posting who understand the
physics implication of func(kx)*func(wt) Vs func(kx +/- wt).
Thanks again.
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

Gene, W4SZ wrote:
"A major part of the ongoing debate is careless use of "phase" as if it
has a single definition."

If Gene has counted at least five different uses in this thread, what
are they?

Phase is defined as 1) The angular relationship between current and
voltage in alternating-current (a-c) circuits. 2) The number of separate
voltage waves in a commercial a-c supply such as single-phase,
three-phase, etc. 3) The time that has elapsed measured from some origin
as a frection of one complete period of a periodic function.

I don`t think the problem in the debate is that the participants don`t
know the circumference of a circle is 2 pi radians or 360-degrees, or
that 360-degrees equals a complete period or one wavelength.

The problem is that some participants don`t admit their mistakes and
hope they are unnoticed or can be hidden by plenty of nonsense. J.J.
Rousseau swore to consecrate his life to the truth. So did Lucy Ball,
but she recommended fibbing about one`s age. It is hard to keep a vow to
be truthful but it is good for the environment.

Too many here struggle for status by hook or crook and fib when the
truth would work better.

Best regards, Richard Harrison, KB5WZI

Current through coils
 

On Tue, 21 Mar 2006 10:58:25 -0600, (Richard
Harrison) wrote:

Too many here struggle for status by hook or crook and fib when the
truth would work better.

Hi Richard,

Adding to the 5 ways to spell phase, we could add to your list to fill
out the 7 deadly sins.

Anyway, it seems one other use of "phase" appears to be in the 90° and
that part missing and presumed taken up by the coil. Who knows, the
landscape is littered with fulminations as you've noted and all have
been pressed into service.

73's
Richard Clark, KB7QHC

Current through coils
 

Richard Clark wrote:
Anyway, it seems one other use of "phase" appears to be in the 90° and
that part missing and presumed taken up by the coil.

Hopefully, some of the myths and old wives' tales will be
dispelled by my updated web page.
--
73, Cecil http://www.qsl.net/w5dxp/current.htm

Current through coils
 

Cecil Moore wrote:
You are silent on the subject of how the lumped-circuit model
explains more current at the top of the coil than exists at
the bottom of the coil. Please share that knowledge with us.

It's really very simple. It functions as a series of L or T networks
with series inductance and shunt capacitance. There isn't anything new
or novel about this.

I think I've done a good job of explaining things, and I've made
measurements and posted results.

Have you made measurements with 1/4WL added to the top of
a mobile antenna?

No, because it is outside the boundary of the antenna being discussed.
We have been talking about short loaded antennas. Not full sized
antennas, not inductors that are nearly self-resonant (tesla coils), or
antennas with distributed loading (helical antennas).

That's an entirely different topic.

Will you believe your measurements when
you measure more current "flowing" into the bottom of the
coil than out of the top of the coil?

If the inductor is nearly self-resonant or in a mode where flux
coupling is low compared to termination impedance, certainly odd things
can happen. RF plate chokes commonly go into modes like that when they
have large inductance to cover the bottom of HF, and have to function
at upper HF also. None of this is rocket science require standing wave
analysis.

As a matter of fact at the first series resonance an RF plate choke can
be accurately analyzed as a pair of back-to-back L networks.

This stuff really isn't new or fascinating Cecil.



It has been proven beyond a reasonable doubt that standing wave
current, func(kx)*func(wt) is not like traveling wave current,
func(kx +/- wt).

So what?

The issue was actual current flowing, not reflected wave current that
only would be a factor in a transient condition.

It almost seems like you are claiming we cannot measure the current
causing loss or causing radiation because of "standing waves". That's
nonsense of course, and I'm sure most people realize it.

Most people probably understand a current transformer will indeed
measure current that causes radiation and heat loss.

Then why can I measure a fixed inductor location in a dfixed antenna,
and range from no taper at all in current to just under 1/3 reduction
in current? Does you standing wave model explain this very repeatable
measurement?

Of course! If you measure the current taper at a point where the
standing wave current slope is near zero, you will measure near
zero taper. If you measure the current taper at a point where
the standing wave current slope is near maximum, you will measure
lots of taper. If you measure at just the right point, you will
measure current flowing into both ends of the coil at the same
time. That's another thing I have asked you to explain with no
response.

I can't explain a problem that exists only in your mind.

73 Tom

Current through coils
 

Gene Fuller wrote:
Hi Tom,

You may be shocked to discover this, but it is possible that my comments
have been reproduced slightly out of context.

At the time, Cecil was still clinging to the notion that if someone did
the measurements properly they could elicit the original phase
information contained in the traveling wave components. In particular,
the space and time coupling represented by the traveling wave function,
cos (kz - wt), was merely hiding. He has since changed his mind, and
unfortunately I seem to have become one of his quotable gurus on this
topic.

A major part of the ongoing debate is the careless use of "phase" as if
it has a single definition. I have counted at least five different uses
in this thread, all correct in their own way, and none interchangeable.

I won't try to explain further. My level of understanding of phase and
such matters is fully satisfactory for me.

73,
Gene
W4SZ

Tom Donaly wrote:

Cecil Moore wrote:



Gene is 100% correct and we all should be grateful for that posting.

Neither you nor Roy have ever made a valid measurement of the
delay through a coil. It is admittedly a difficult measurement
to make directly. Ramo and Whinnery say it "is usually of
prohibitive difficulty".



I think that if Gene believes that, he should redo his math.
73,
Tom Donaly, KA6RUH

You're right, Gene, I'm shocked! shocked! to learn that Cecil might
distort anything anyone might write. I never for a moment, though,
thought there
was anything wrong with your understanding. It was Cecil's understanding
of your understanding that was in doubt.
73,
Tom Donaly, KA6RUH