Cecil Moore wrote:

wrote:

Would you please describe for me the physical arrangement of an IDEAL
inductance.


Art, picture a dimensionless point in your mind. Define that point as
an inductance without dimensions, without capacitance, and without
resistance.
There is your "IDEAL inductance" and exists ONLY in the human mind and
certain
computer models. Since it is dimensionless, the current into the point
and the
current out of the point are the same current because they are the same
point
and, of course, the dimensionless point is traversed instantaneously.

Now, without modification, extend that dimensionless concept to a one-foot
diameter, one-foot long bugcatcher coil, wound with 60 feet of
real-world wire.
Assert that the bugcatcher coil has virtually identical characteristics
to that
previous dimensionless point in your mind. Use a computer model's
dimensionless
inductor feature to prove your point.

That's the present "physical arrangement". :-)
--
73, Cecil http://www.qsl.net/w5dxp


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There are lots of ways to make inductors, (coils, transmission lines,
meander lines, etc.) but there is only one inductance.
73,
Tom Donaly, KA6RUH

"Cecil Moore" wrote in message
...
wrote:

Would you please describe for me the physical arrangement of an IDEAL
inductance.

Art, picture a dimensionless point in your mind. Define that point as
an inductance without dimensions, without capacitance, and without
resistance.

I'll stop right there, Dimensionless objects which relies on proximity
effects
is beyond my ken. To use this as an aproach of dimensional devices with
NEC to prove something is like building on sand This is like using complex
circuitry
and ignoring connection lines that radiate. In mathematics we use a mythical
addition
of root minus one as a sort of gimmic to solve a problem but we always
remove the gimic
before the real world answers are given, yet you want to keep the gimmic,
ala an imaginary
thing which is dimensionless and thus has zero proximity effects even tho
proximitry effects
is what generates inductance in a dimensionless form. And you want me to use
this imaginary
dimensionless aproach with NEC which deals with the real world where
inductance cannot
be dimensionless ? This is where the coil argument started since the field
density inside a coil
is more than that at any point physically and dimensionaly outside the coil
which leads to lumped load errors.
I am hoping that Ian will address the question in a more serious way and not
as a way to
buttress a personal agenda. I suppose I should have made it a seperate
posting so it would
not be perceived in taking sides e.t.c. Actually I modelled the coil to
real world dimensions
with a NEC program with copious segments that supplied current levels at
multiple points
around each turn to get my answers which this thread now suggests that NEC
answers could me incorrect
thus I am following the thread but not partaking in it.
My personal belief is that making EZNEC a part of the debate is a mistake
since it contains
boundaries that most NEC computor do not have and the coil problem is
outside its useable
boundaries or imposed limits.If a lumped load is viewed as dimensionless
then a computor
can be excused as supplying a dimensionless response which can evoke a
'garbage in....'
type comment.
Like most technical things there is nothing wrong with the use of items
such as EZNEC
within the limits prescribed by Roy and the coil question is outside the
useable limits
of the EZNEC program.
This response is not meant to be personal to anybody or any program
mentioned
Art


There is your "IDEAL inductance" and exists ONLY in the human mind and
certain
computer models. Since it is dimensionless, the current into the point and
the
current out of the point are the same current because they are the same
point
and, of course, the dimensionless point is traversed instantaneously.

Now, without modification, extend that dimensionless concept to a one-foot
diameter, one-foot long bugcatcher coil, wound with 60 feet of real-world
wire.
Assert that the bugcatcher coil has virtually identical characteristics to
that
previous dimensionless point in your mind. Use a computer model's
dimensionless
inductor feature to prove your point.

That's the present "physical arrangement". :-)
--
73, Cecil http://www.qsl.net/w5dxp


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Tom Donaly wrote:
You and Richard need a refresher course in electromagnetics. I hope
Yuri doesn't fall into the same trap.

As usual, zero technical content from you.

Tom, here's a "circuit" for you.

+--------------------------------+
| |
source Load
| |
+--------------------------------+

The source is delivering 200 watts in the form of V=100V and
I=2A in phase. The load is 4050 ohms. Using your circuit model,
you assert that the current through the source is equal to the
current through the load since it is a series circuit. Yet, if
the current through the 4050 ohm resistor were actually 2.0A,
the power to the load would be about 16,000 watts, thus violating
the conservation of energy principle.

Is there a current drop from the source to the load? Of course!
Does this violate Kirchhoff's laws? Of course not!

Why doesn't your circuit model work? Because the wires
between the source and the load are 1/4WL of 450 ohm ladder-line
thus rendering the circuit model invalid for the application.

YOUR CIRCUIT ANALYSIS MODEL DOES *NOT* WORK ON DISTRIBUTED NETWORK
PROBLEMS!!!
--
73, Cecil http://www.qsl.net/w5dxp


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Tom Donaly wrote:
There are lots of ways to make inductors, (coils, transmission lines,
meander lines, etc.) but there is only one inductance.

Have you ever seen the equivalent circuit of a transmission
line presented with "only one inductance"?


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On Wed, 20 Oct 2004 04:49:52 GMT, "
wrote:

Actually I modelled the coil to
real world dimensions
with a NEC program with copious segments that supplied current levels at
multiple points
around each turn to get my answers which this thread now suggests that NEC
answers could me incorrect
thus I am following the thread but not partaking in it.

Hi Art,

Read the thread where it is correctly described and stick with a
winner. After all, the difference between the point inductor, and the
helical one offers barely half a dB difference in the outcome. No one
here could possibly measure that spread accurately (about the quarter
of the width of an S-Meter's needle).

73's
Richard Clark, KB7QHC

On Wed, 20 Oct 2004 00:16:49 -0500, Cecil Moore
wrote:
Does this violate Kirchhoff's laws?
Of course it does, several times.

Like most technical things there is nothing wrong with the use of items
such as EZNEC
within the limits prescribed by Roy and the coil question is outside the
useable limits
of the EZNEC program.

Art,
in EZNEC version 4.08 by using HELIX definition menu in WIRES you can define
real coil, with segments. I did that at the beginning of this thread using 10m
quarter wave loaded antenna showing the difference in the current at the coil
ends and also what happens when you move the coil from 1/2 to 3/4 way up from
the feed point. That correlates close to modeling of loading inductance by
using stub and what was found by measurements in reality.
If one insists in modeling loading coil as inductance with zero physical size,
then you get W8JI results (same current at the ends)
There is a progress, even if some still can't swallow it.

73 Yuri, K3BU.us

Richard Clark wrote:
Read the thread where it is correctly described and stick with a
winner. After all, the difference between the point inductor, and the
helical one offers barely half a dB difference in the outcome.

The difference in the outcome of the currents is way more
than half a dB. It's more like 12 dB.
--
73, Cecil http://www.qsl.net/w5dxp


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Richard Clark wrote:

Cecil Moore wrote:
Does this violate Kirchhoff's laws?

Of course it does, several times.

Got news for you, Richard. The current drop from a current
loop to a current node is NOT a violation of Kirchhoff's laws.
It is a characteristic of distributed networks.
--
73, Cecil http://www.qsl.net/w5dxp


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On Wed, 20 Oct 2004 09:17:57 -0500, Cecil Moore
wrote:
a violation of Kirchhoff's laws.
that's right