Richard Clark wrote:

Cecil Moore wrote:
a violation of Kirchhoff's laws.

that's right

The current in a series loop is NOT constant when the loop is a
reasonable percentage of a wavelength and there are reflections
present. Please provide proof that violates Kirchhoff's laws.
--
73, Cecil http://www.qsl.net/w5dxp


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On Wed, 20 Oct 2004 09:34:39 -0500, Cecil Moore
wrote:
Please provide proof that violates Kirchhoff's laws.
Read your own post for proof.

Tom Donaly wrote:
"You and Richard need a refresher course in electromagnetics."

This Richard agrees a refresher course could help. I no longer read the
Proceedings of the IRE for fun. It`s been over 50 years since I last
darkened the halls of academia.

I remember a few things. One hangup I see here is the rule that the
current in a series circuit is always the same everywhere.

True for circuits small in terms of wavelength. False for unmatched (not
terminated in Zo) circuits of a size significant in terms of wavelength.

The standing-wave antennas of this thread are less than 1/4 wavelength,
but they`re still significant in terms of wavelength with or without
loading coils. They are open-circuited and make a big reflection from
their open-circuited ends. This reflection causes a current which varies
from zero at the open-circuit end to something substantial back a ways
from the open-circuit. Between substantial and zero is a current drop.

My favorite author. F.E. Terman depicts this current distribution in a
dipole (two 1/4-wave antennas back to back) in Fig. 23-2 on page 866 of
his 1955 edition. For a whip worked against ground, the current
distribution is either half of the dipole representation.

Look at Fig.23-2. Anyone can see the current drops to zero at the
antenna tips. Loading coils won`t change that. Coils added to bring
total antenna inductance to resonance with its capacitance occupy space.
Current through a loading coil takes time to traverse the coil. By the
time current has made the trip through the coil, current arriving from
the source is out of phase to some extent with that arriving through the
coil. The delays in transit to both ends of the coil are likely not
equal. The inequality in phase results in a difference in volts, amps,
and impedance at the two coil ends.

Recall, we are discussing r-f, traveling as a wave from both terminals
of a generator. It is not d-c emerging from one battery terminal and
entering another.

Cecil is exactly correct in his characterization of how waves supeerpose
to produce standing-wave variations in voltage, current, and impedance
in the total series circuit.

Proof has been offered by modeling, and measurement. You may accept or
reject the observations of others. You could also make your own.

Best regards, Richard Harrison, KB5WZI

Yuri
I was relying on statements from Roy in the past where close spaced wires
causes errors.
In a inductance coil each wire is in close proximetry to other wires in the
coil that undergo
voltage changes Thus by his statements his limited number of segments
available could cause errors.
It was for this reason my modelling picture was the image of a real coil
with close spaced
coils und unlimited segments available which when increased did not change
the supplied.results,
the test for finality in modeling.
One of the reasons I chose this aproach was when modeling critically coupled
coils, lumped loads
which are imaginary and dimensionless gave problems with critically coupled
distances from the
center line of a coil ie inside the coil, to distances to outside the coil
in a single plane, as well as the
capacitive coupling provided by the length and shape of the coil
To me it was important for the program to do it's job with a real life
coil without any intrusions
and assumptions imposed by the operator. If a program has limitations
imposed then it is a sign
that human overuling intervention is required to prevent the program from
running amuck.
But as I stated earlier, I have no intention of getting involved in this
thread with its infighting
when I respect some people from both camps.and where as previously stated by
a poster
some responses are posed like a language but are non decipherable
Art

"Yuri Blanarovich" wrote in message
...
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 your own post for proof."

An antenna loading coil may have unequal current ingress and egress
without violating Kirchoff`s law the same way a speaker matching
transformer or pi-network does. The input and output impedances are
different, though the power input and output are nearly the same.

Best regards, Richard Harrison, KB5WZI

Tom Donaly wrote:
Next, Cecil, you're going to be talking about a "current gradient"
and a "scalar current field." Here's a question for you, Cecil, and
Richard Harrison, and Yuri, too: how do you take the gradient of
the current at a point on a transmission line, and, if were possible
to do so, what is the physical significance of the result?
73,
Tom Donaly, KA6RUH

The standing wave current profile along, for example, a quarter wave
radiator is a cosine function. The gradient then would be the
derivative of the cosine function which is a -sine function.

73, ac6xg

Richard Clark wrote:
Cecil Moore wrote:
Please provide proof that violates Kirchhoff's laws.

Read your own post for proof.

If you think my postings provide proof of a violation of
Kirchhoff's laws, you simply do not understand distributed
network systems and analysis.
--
73, Cecil http://www.qsl.net/w5dxp


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Jim Kelley wrote:
The standing wave current profile along, for example, a quarter wave
radiator is a cosine function. The gradient then would be the
derivative of the cosine function which is a -sine function.

Yep, the feedpoint is at a current loop (max). The open end of the quarter
wave radiator is obviously at a current node (min). There are electrically
90 degrees of signal between the current loop and the current node on a
standing-wave antenna or on a transmission line with standing waves.
--
73, Cecil http://www.qsl.net/w5dxp


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I was relying on statements from Roy in the past where close spaced wires
causes errors.


Roy outlined the limitations as far turns spacing for minimum error, but for
the purpose of illustration, the HELIX menu is a big help in modeling or
studying the effect of loading coils. In my original example I tried to obey
the limitations and wanted to demonstrate that EZNEC can model real life coils
and display the current distribution across them.

This is especially important when modeling parasitic beams with loaded
elements.

73 Yuri

Cecil Moore wrote:
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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You still don't get it, Cecil, which is o.k. since I didn't expect you
to. I don't doubt that Yuri can find a coil that exhibits a different
current at one end than at the other; I have an antenna that exhibits
the same behavior, and I made it that way on purpose. However, the
term "current drop" as used by Yuri was wrong. There is no place for
it in electromagnetic theory, and if you had known enough theory to
understand that, you wouldn't have answered as you did.
73,
Tom Donaly, KA6RUH