Current through coils
 

Richard Clark wrote:
This is simply proof of an exercise in futility through the
misapplication of the theory of transmission lines to lumped
components.

One certainly has to be careful. But Dr. Corum's formulas
matched my measurements closer than I expected.

One thing is for sure. One cannot use the presuppositions
of the lumped-circuit model to prove the validity of the
lumped-circuit model and that is what has happened so
far. One also cannot use a signal with unchanging phase
to measure the phase shift through a wire or coil.
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

Richard Harrison wrote:
Tom, W8JI wrote:
"If an inductor by itself delayed phase as much as Cecil claims, we
could build a phase or time delay system with only a large inductor."

Recall that another name for the inductor is a "retardation coil", and
that the time constant of an inductor having an L in henrys and a
resistance in ohms is equal to L/R.

Yes, it's been known for over a century that the phase of the current
through an inductor lags the voltage across it, resulting in retardation
of the current relative to the voltage. And the time constant you refer
to is of course the time constant of the rise or decay of the current
through an inductor to which a voltage step is applied.

I don't see the connection between these and the contention that the
current into and out of an inductor are unequal. If there is one,
perhaps you can explain it. My texts all show a single equation relating
the voltage across an inductor to the current through it, as follows:

v = L * di/dt

This holds at all frequencies, i.e., all rates of change of current, and
it's from this that the above mentioned characteristics follow. If the
currents at the two inductor terminals are to be different, we'll need
two equations, one for the input current and one for the output current.
That is, v = f1(di1/dt) and v = f2(di2/dt), where f1 and f2 are
different functions. Have you come across such a set of equations in
your searches through your textbooks, or are the authors unaware of
Cecil's theories?

Roy Lewallen, W7EL

Current through coils
 

Roy Lewallen wrote:
Have you come across such a set of equations in
your searches through your textbooks, or are the authors unaware of
Cecil's theories?

I can't take credit for them, Roy, since I studied them at
Texas A&M in the 50's. Much of it appears in Ramo and
Whinnery's "Fields and Waves" and Johnson's "Transmission
Lines and Networks". They are just the rules of the
distributed network model of which the lumped-circuit
model is a subset. In any situation where the lumped-
circuit model yields different results than the
distributed-network model, the lumped-circuit model
is wrong.

The lumped-circuit model presupposes the conclusions
that some people are presenting as fact. Obviously,
the lumped-circuit cannot be presented as evidence
of proof of its presuppositions. But it appears that
is exactly what has happened. The lumped-circuit
model presupposes faster than light propagation
of signals. That alone should be enough to raise
a red flag. Can someone prove faster than light
speed by quoting the presuppositions of the
lumped-circuit model?

Quoting Dr. Corum again: "Lumped circuit theory
isn't absolute truth, it's only an analytical
theory ... The engineer must either use Maxwell's
equations or distributed elements to model reality."

My 75m bugcatcher meets his criteria for situations
where his VF equations work. It yields a VF of
0.0175 for the bugcatcher coil. That VF works
just like the 0.66 VF works for RG-213. On a coil
physically like the W8JI test coil but with 50 uH
inductance, I see coil resonances at 9 MHz, 27 MHz,
and 45 MHz, just as if it were 1/4WL of transmission
line. It appears that the calculated VF works over
a wide frequency range.

To prove the presuppositions of the lumped-
circuit model, a standing wave current is
used to measure phase. We already know the phase
of a standing wave current is unchanging all
along a 1/2WL dipole, per Kraus, yet some people
keep using standing wave current with its unchanging
phase to try to measure phase shift as if it were a
valid thing to do. One cannot measure a phase shift
in 45 degrees of dipole using standing wave current.
Why is it surprising that one cannot measure a
phase shift in 45 degrees of coil? There's no
current phase shift from the top of the coil
to the tip of the antenna either.
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

On Wed, 15 Mar 2006 18:19:21 -0800, Roy Lewallen
wrote:

This is a misapplication of transmission line formulas. The "C" in those
formulas is the shunt capacitance per unit length between the
conductors, not a series or longitudinal capacitance as used here. In
order to use the transmission line formulas, you have to have a second
conductor and determine the C per unit length between the two
conductors. Otherwise, you (or Cecil) have to come up with some other
equations. Some of the more picky of us readers will of course then ask
for the source and/or derivation of those other equations.

Hi Roy,

Well, it (the misapplication) certainly is that. That no two numbers
agree to the same problem misses more compelling evidence that hardly
demands strict accuracy in results obtained from any formula.

In short, no "other" equations are going to prove what cannot be
generally demonstrated.

Barring startling results demonstrating how either of the two coils
offered here in evidence reveal multiple resonances, that is enough to
kill the thread without needing tedious computations.¹

Another is the howler that this is all based upon the "coil's
characteristics," and Cecileo proved the Sun orbits the moon by
employing the bed of his truck in the exact solution.² This is called
new-age math with an harmonic convergence. It was convenient of all
his reference sources to include this truck factor as a hidden
variable - accessible to only those who know the secret handshake.

Just kidding, of course.

In fact, the authors tread very lightly in the context of a ground,
mentioning it only once as a necessity for
"characterizing the impedance of a structure
at a pair of terminals" [your point]

When the speculation is that the coil presents a 1:1 replacement for
the delay of the "missing" segment of the resonant antenna, then this
premise stumbles at the starting blocks. If I shorten the whip, then
the shorthand of:
On Tue, 14 Mar 2006 21:45:06 GMT, Cecil Moore wrote:
The velocity factor can also be measured from the self-
resonant frequency at 1/4WL. VF = 0.25(1/f)
offers this promise:
Make a smaller inductance (reducing turns will do)
to present a higher self-resonant frequency.

VF will fall.

From this, the delay climbs
to replace the shortened whip's missing angular contribution.

The reductio-ad-absurdum is that we repeat the trimming of the whip
until the inductance disappears.³ Ironically this leaves us with a
very short mast that now resonates! If we closed our eyes really,
really hard, and wished for a coil with a very high self resonance, it
could replace the mast too.

I see new marketing possibilities for 80 and 160 Meters.

¹ ² ³ Let's see, without any deep computations I count three thread
busters here. Offering the same proviso of probable computation
errors committed here, I would point out that only one thread buster
need survive to present the obvious fate to this theory.

73's
Richard Clark, KB7QHC

Current through coils
 

On Thu, 16 Mar 2006 03:30:36 GMT, Cecil Moore wrote:
One also cannot use a signal with unchanging phase
to measure the phase shift through a wire or coil.
Ah, Zen poetry disguised as erudition. I can top that!
One cannot cook a one minute egg using a compass.

Current through coils
 

On Thu, 16 Mar 2006 03:20:38 GMT, Cecil Moore wrote:
In addition to those, there other soft
spots and double dips along the frequency line.
not a very good transmission line model then, is it?

Current through coils
 

On Thu, 16 Mar 2006 03:20:38 GMT, Cecil Moore wrote:

Its first solid resonance was 9 MHz (1/4WL), its second solid
resonance was 27 MHz (3/4WL), and its third solid resonance
was 45 MHz (5/4WL).

What are they when you raise the assembly (I distinctly note that this
is NOT the resonance of the COIL you are speaking of) two feet higher?

Current through coils
 

Roy, W7EL wrote:
"I don`t see the connection between these and the contention that the
current into and out of an inductor are unequal."

Nor do I. Tom was not making a case for inequality of current in and out
of a coil either. He was just making an inaccurate statement.

Cecil has a good case. Straight wire and coiled wire have the same
properties, only more or less of them. When they are in the path of a
traveling wave and a reflection of that wave comes back from the
opposite direction, they respond similarly. An interference pattern
exists on the coil as it does on straight wire if the distance is
comparable to a wavelength. Superpositon makes both volts and amps vary
along the route.

So, indeed the current at one end of a coil in that situation can be
different at from that at the other end, the same as it would along a
wire.

Distributed network theory is newer than lumped network theory but both
have been around plenty long enough to be well established. I don`t
think Cecil is breaking any new ground.

Best regards, Richard Harrison, KB5WZI

Current through coils
 

Richard Harrison wrote:
Roy, W7EL wrote:
"I don`t see the connection between these and the contention that the
current into and out of an inductor are unequal."

Nor do I. Tom was not making a case for inequality of current in and out
of a coil either. He was just making an inaccurate statement.

What was the inaccurate statement he made? I've found Tom very willing
to correct errors, so I'm sure he'll correct it if we point it out to him.

Cecil has a good case. Straight wire and coiled wire have the same
properties, only more or less of them. When they are in the path of a
traveling wave and a reflection of that wave comes back from the
opposite direction, they respond similarly. An interference pattern
exists on the coil as it does on straight wire if the distance is
comparable to a wavelength.

Which distance do you mean -- the length of the coil or the length of
the wire?

Superpositon makes both volts and amps vary
along the route.

So, indeed the current at one end of a coil in that situation can be
different at from that at the other end, the same as it would along a
wire.

Yes, indeed. As I explained in several earlier postings, if you begin
with a coil and slowly stretch it out, the current distribution will go
from something resembling that of a lumped inductor (equal currents in
and out) to that of a straight wire (sinusoidal distribution). So "a
coil" can have any current distribution along that continuum, allowing
us to "prove" just about anything we wish as long as we don't say what
kind of coil we're talking about. In between the extremes, a third
distribution can occur, as King described in his book: when the coil
length is much less than a wavelength but the turns are loosely coupled,
you get a current that's highest in the middle and lower at both ends.
The disagreement regards the currents in what would qualify as a lumped
inductor -- one with very good coupling between turns, coil length very
short in terms of wavelength, and no significant coupling to other
conductors, but regardless of the length of wire it's made of. For that
case, it's been theoretically and demonstratively shown to be equal at
both ends.

Distributed network theory is newer than lumped network theory but both
have been around plenty long enough to be well established. I don`t
think Cecil is breaking any new ground.

His conclusions are sure new and different, and unlike established
theory, his theories don't seem to be subject to equations which
describe them quantitatively.

Roy Lewallen, W7EL

Current through coils
 

Richard Clark wrote:
Barring startling results demonstrating how either of the two coils
offered here in evidence reveal multiple resonances, that is enough to
kill the thread without needing tedious computations.¹

Last night I posted 1/4WL, 3/4WL, and 5/4WL measured resonant
points using the same coil stock as W8JI but with a shorter
50 uH coil. This coil 2" dia, 8 tpi, 8.5" long. It was
sitting on a mag mount on my metal desk.

When the speculation is that the coil presents a 1:1 replacement for
the delay of the "missing" segment of the resonant antenna, then this
premise stumbles at the starting blocks.

Nobody said anything about a 1:1 replacement. That was just
somebody's strawman.
--
73, Cecil http://www.qsl.net/w5dxp