Current through coils
 

On Thu, 16 Mar 2006 09:09:40 -0800, Richard Clark
wrote:

On Thu, 09 Mar 2006 21:40:40 GMT, "Cecil Moore"
wrote:

Your 100uH coil above exhibits 60 degrees of phase shift
even for the voltage and that's 1/6 wavelength

On Thu, 16 Mar 2006 08:56:19 GMT, Cecil Moore wrote:

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.

We all know who "somebody" is. [threadbuster #4]

But if this is news to you, it must have been one of your other
personalities (Hokum's Razor?) at the keyboard who posted the message
at the top.


:-) :-) :-) :-) :-)

It just occurred to me that those two posts were a week apart (more or
less) and denote a phase change (the one cancels the other if they
were to vectorally combined).

Thus and forever more, this proves that newsgroups (when heavily fed
from a source of confusion, linearly loaded with nonsense, and
terminated with a embarrassing revelation) exhibit transmission line
properties and can transform a stupid idea (at the top) into a
brilliant one (at the bottom) - or versa vice.

In conformance to transmission line properties, this cycle of phase
reversals is repeated every
1 / [1 + tan (c · Vf / posts)]² Years

Current through coils
 

On 16 Mar 2006 12:19:20 -0500, "Bill Turner" wrote:

Is the current the same at both ends of a mobile whip's loading coil?

Sorry Bill,

Depends....

Yes, of course not. The clear and compelling lesson to be learned is
that you CANNOT apply Kirchhoff's laws to networks that are large in
relation to wavelength. This single caveat was drilled into me in
sophomore EE.

Any variance in current measured, that is larger than errors that may
be attributed to is measurement PROVES that the size in relation to
wavelength necessarily invalidates Kirchhoff solutions. This single
truth has been observed by me at the calibration bench.

As Roy noted, it demands another set of equations. In the Metrology
field, that is what we were paid to use, or to derive. Suffice it to
say that modeling programs replace the tedium of scribbling out that
math, and just getting on with the next act.

73's
Richard Clark, KB7QHC

Current through coils
 

"Ian White GM3SEK" wrote:
That was not a "shortcut" or approximation.

It really doesn't matter if it is or it isn't. I was quoting another pretty
smart guy who seems to know the history of these models. He said
Maxwell's equations matured first, then the distributed network model
matured as a simplified subset of Maxwell's equations, then the lumped-
circuit model matured as a subset of the distributed network model.
But a chicken/egg argument is meaningless except for historical
accuracy. We are in the present looking at those models.

In that limiting case, the current at the two terminals of a pure
inductance must be the same in both magnitude and phase.

There's that catch word, "pure". Pure inductances do not exist
in the real world. They are a construct of the lumped-circuit
model and are presupposed to have the characteristice that
you mention. One cannot prove the validity of that model by
quoting the presuppositions. A 75m bugcatcher coil is NOT
a pure inductance.

By "current" we
mean the simple, straightforward movement of charge. If you count the
electrons in and out at the two terminals, there can be no difference in
either magnitude or phase because that would require electrons to be
stored or lost from somewhere - which inductance cannot do. Kirchhoff's
current law recognises the logic of this.

Standing wave current with its cos(kz)*cos(wt) equation is not constrained
by those rules since the phase of the standing wave is everywhere zero deg
for a 1/2WL thin-wire dipole.

This is how inductance always works in every type of non-radiating
circuit, both in theory and in real life.

A pure inductance cannot work that way in real life because it doesn't
exist in real life. If the forward current is in phase with the reflected
current at one end of the coil, the current will be a maximum (loop)
at that point. If the forward current is 180 degrees out of phase with
the reflected current at the other end of the coil, the current will be a
minimum (node) at that point. Please take a look at:

http://www.qsl.net/w5dxp/3freq.gif

How does one explain the current reported by EZNEC at two times
the resonant frequency?

When developing a new theory, it is normal, standard required practice
to test it for simplified, limiting cases that we already understand.
The new theory MUST work for all these test cases; it MUST connect
seamlessly with everything we already know.

The distributed network model predates my birth by decades and is not
new. It is known to work in situations where the lumped-circuit model
fails. It has never been known to fail in a situation where the lumped-
circuit model works.

At his point, some heckler pipes up: "Ah, but what about Einstein?"
Thank you, sir - the perfect example to prove my point! If Einstein's
equations of relativity are tested for the limiting case where
velocities are very low, they connect seamlessly into Newton's laws of
motion. If they hadn't, Einstein would have thrown them out and gone
back to think again.

The distributed network model is to relativity as the lumped-circuit model
is to Newtonian physics. Newtonian physics is a subset of relativity.
The lumped-circuit model is a subset of the distributed-network model.

When Cecil's theory is tested for the simple limiting case of pure
inductance, it MUST join up seamlessly with conventional circuit theory.

It's not my theory and it does indeed join up seamlessly. It is the lumped-
circuit model that does not join up seamlessly with Maxwell's equations.
How could it since it assumes faster than light speed of current flow?
The presuppositions of the lumped-circuit model even violate the
theory of relativity.

If it requires anything that "don't fit", such as a phase shift in
current through a pure inductance, or special kinds of "current" that
are different from the simple, straightforward movement of charge
(electrons), then the theory fails.

It doesn't require anything of pure inductances since pure inductances
don't exist in reality. It requires that real world inductances obey the
laws of physics.

If one doesn't understand the implications of the equation for standing
wave current, one needs to crack open that old dusty math book.
--
73, Cecil, W5DXP

Current through coils
 

Richard Clark" wrote:
On Thu, 09 Mar 2006 21:40:40 GMT, "Cecil Moore"
wrote:

Your 100uH coil above exhibits 60 degrees of phase shift
even for the voltage and that's 1/6 wavelength.

That does NOT say the coil replaces 60 degrees of wire in the antenna.
One who thinks such is mistaken. The phase shift in the coil is what it
is. It usually does NOT correspond to the phase shift of the wire it
replaces.
The point of that statement was that real world phase shift is never zero.
The one-way phase shift is known to be 90 degrees at the self-resonant
frequency.

On Thu, 16 Mar 2006 08:56:19 GMT, Cecil Moore wrote:

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.

We all know who "somebody" is. [threadbuster #4]

But if this is news to you, it must have been one of your other
personalities (Hokum's Razor?) at the keyboard who posted the message
at the top.

Some people have misunderstood the meaning of that statement. See above.
So many jumping to conclusions - so few trying to understand.
--
73, Cecil, W5DXP

Current through coils
 

"Richard Clark" wrote in message
...
Cecil Moore wrote:
Isolating the magmount would be disconnecting the
ground plane from a 1/4WL antenna and would contribute
nothing of value to the discussion.

Certainly not for you, that is apparent. It would only more closely
conform to your reference material's isolated coils, and that would
jeopardize your "confirmations" n'est pas?

On the contrary, Tesla coils are operated over a large ground plane.
The sphere at the top functions like a top hat. Everyone really should
read the referenced Corum papers to avoid misconceptions like this
one.
--
73, Cecil, W5DXP

Current through coils
 

On Thu, 16 Mar 2006 18:20:19 GMT, "Cecil Moore"
wrote:
On Thu, 09 Mar 2006 21:40:40 GMT, "Cecil Moore"
wrote:
Your 100uH coil above exhibits 60 degrees of phase shift
even for the voltage and that's 1/6 wavelength.
That does NOT say the coil replaces 60 degrees of wire in the antenna.
Of course not. 1/6 wavelength of wire doesn't exhibit 60 degrees
phase shift - does it?
One who thinks such is mistaken.
Less than a week to this new phase shift in the non-linear dynamics of
Newsgroups-as-transmissionline. ;-)

The phase shift in the coil is what it is.

More Zen from the edge of Nirvana. Let me try mine:
The soup spoon in a magnetron is what Campbell's is to Andy Warhol.

Give us another!

Current through coils
 

On Thu, 16 Mar 2006 18:23:24 GMT, "Cecil Moore"
wrote:
Everyone really should read the referenced Corum papers
to avoid misconceptions like this one.

This is coasting with the brakes set on self-referentially.
Still amusing however.

Current through coils
 

"Bill Turner" wrote in message
...
I've been following this mind-numbing discussion for days now and still
don't have the answer to the original question:

Bill, I posted an example of me, as a naive ham, reducing the size of my
dipole from 180 feet to 90 feet by adding loading coils. Please follow
that experimental excursion to find out what the discussion is all about.

Is the current the same at both ends of a mobile whip's loading coil?

The mobile antenna is a standing wave antenna. It has a forward current
and a reflected current, both traveling waves, flowing through it.

1. The forward current flowing through the coil is close to the same
magnitude at both ends of the coil.

2. The forward current phase shift through the coil is difficult to measure
but it is NOT zero. It is more in the neighborhood of tens of degrees.

3. The reflected current flowing back through the coil is close to the
same magnitude at both ends of the coil.

4. The reflected current phase shift is close to the same as the
forward current phase shift, i.e. tens of degrees..

5. The standing wave current, the only one measured so far, is the
phasor sum of the forward current phasor and the reflected current
phasor. The magnitude of the standing wave current depends upon
the relative phase between the forward current and reflected current.

To see some variations please visit: http://www.qsl.net/w5dxp/3freq.gif

When one realized that the standing wave current at the bottom of
the coil is 0.1 amp while the standing wave current at the top of
the coil is 2 amps, one comprehends why he must abandon the
concept that standing wave current flows.

From the equation for the standing wave current, cos(kz)*cos(wt),
one can be see that the standing wave current is not a normal current.
This is explained in terms of light waves in "Optics", by Hecht.

6. Since the forward current phasor and reflected current phasor are
rotating in opposite directions, the phase of the standing wave current
is fixed and close to zero degrees all up and down the antenna, from
feedpoint to tip top. Since the phase of the standing wave is unchanging,
it cannot be used to measure the phase delay through a coil. All of the
delay measurements, except the self-resonant frequency measurements,
have used standing waves which are incapable of phase transitions in
the average loaded mobile antenna.

The phase of the standing-wave current is fixed close to zero degrees
until the antenna gets electrically longer than 90 degrees. Then it shifts
abruptly by 180 degrees and remains fixed at that new value for another
90 degrees. This is illustrated in Kraus', "Antennas for All Applications",
3rd edition, Figures 14-4 - 14.6.
--
73, Cecil, W5DXP

Current through coils
 

Cecil Moore wrote:
Note that at the frequency where the dipole is 1/2WL and resonant,
it is 180 feet long and 180 degrees long so the number of feet of
wire is also the number of degrees of antenna. Here is my 1/2WL
dipole with current pickup coils installed at points 'x' and 'y' and
FP is the feedpoint,the impedance of which is 60 ohms.

------------------------------FP-------x---------------y-------

Total length is 180 feet. The distance between 'x' and 'y' is 45 feet.
Since feet = degrees in this case, the number of degrees between
'x' and 'y' is known to be 45 degrees from antenna theory. Those
45 degrees are what I am going to attempt to replace with a coil.

So I adjust the feedpoint current to one amp at a reference phase
angle of zero degrees and measure the current at 'x' and the current
at 'y'. The current at 'x' is 0.92 amp at 0 deg. The current at 'y' is
0.38 amp at 0 deg. Already I am not understanding my measurements.

Your measurements are probably wrong.

When did you measure that? After we resolve the error in current, we
can move on.

73 Tom

Current through coils
 

Bill Turner wrote:
I've been following this mind-numbing discussion for days now and still
don't have the answer to the original question:

Is the current the same at both ends of a mobile whip's loading coil?

Bill, W6WRT

Bill,

Did you read this? Actual measurements!!

http://www.w8ji.com/mobile_antenna_c...ts_at_w8ji.htm

As Richard Clark said, it all depends on the physical size and
constrution of the inductor and the antenna above the inductor. In a
reasonably well-constructed antenna the difference is small.

Anyone who says otherwise is just guessing.

73 Tom