Thanks for the correction regarding proximity effect. In that case,
Reg's program should report the loss more accurately than EZNEC when the
turns are very closely spaced.

Yes, indeed, EZNEC does account for the capacitance -- it comes about
from the coupling of fields between turns, which is at the heart of the
fundamental NEC-2 electromagnetic field calculations. As I said, the
self-resonant frequency reported by EZNEC is pretty close to that
calculated by your program.

Roy Lewallen, W7EL

Reg Edwards wrote:
EZNEC doesn't model proximity effect (significant only when the
turns are pretty closely spaced) but I don't think Reg's program
includes proximity effect, either.

Roy Lewallen, W7EL


======================================

Yes it does!

But you can forget it. It doesn't matter except when calculating efficiency.
It has no affect on how the thing works which is what you are all
so-aggressively fighting about. You'll soon be using assault weapons.

Program "Loadcoil" also includes the ALL-IMPORTANT COIL CAPACITANCE (which I
suspect Eznec does not - I never use it) - the existence of which the
whole set of you block-heads, so-called electrical engineers, appear to be
entirely ignorant.

We ARE dealing with alternating currents.

Oh Boy - I enjoyed typing that! ;o)
----
Reg, G4FGQ

Jim Kelley wrote:


Tom Donaly wrote:

Jim Kelley wrote:

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


Jim,
current, in a wire, is the total current density integrated across
a cross section of the wire. It's a vector, as is the current density.
Now tell me, how do you take the gradient of a vector? David K. Cheng,
in his book Field and Wave Electromagnetics, defines the gradient
operation this way: "We define the vector that represents both the
magnitude and the direction of the maximum space rate of increase
of a scalar as the gradient of that scalar." He wrote "scalar,"
not "vector," Jim. You and the rest of the boys are acting as if
current had magnitude but no direction, whereas it has both.
73,
Tom Donaly, KA6RUH


Not sure why you don't like gradients, Tom. I'm sure Mr. Cheng is
undoubtedly correct, but I'm just as sure he didn't intend that sentence
as any sort of definition of the term "gradient".

Actually, he did. It's the accepted definition of the term in
electromagnetics. You and Cecil are using the term in a more
general fashion which you've made up for the purpose. It doesn't
make much sense in an elecromagnetic setting. Similarly, Yuri,
Richard and Cecil made up a very loose term "current drop" for
a change in current at two ends of a coil. That was misleading
and wrong if they were trying to convey something about the
electromagnetics of a coil, which they were. I've seen you fellows
pick each other to death over trivia time and again. It's time
you paid attention to what you write.

That's something you
have apparently read into it. The gradient in our case (since you
proposed the question) would be expressed as the superposition of
forward and reverse currents, with magnitude and phase (or direction if
you prefer) written as a function of either position or angle *along*
the radiator. It's nothing fancy. Honest. It's simply the rate of
change of current as a function of position. The gradient across the
radiator at any given point along the radiator could then be determined
using some additional parameters - if someone were really that
interested in it (which I'm not).

73, ac6xg


How could the gradient be in your case if I proposed the
question?
73,
Tom Donaly, KA6RUH

Tom Donaly wrote:
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.

I've been in Las Vegas for ten days and didn't see Yuri's posting.
All I know is there is a "current drop" from the current maximum
point to the current minimum point on a transmission line with
reflections. So exactly how did Yuri use "current drop"? If it is
through a mobile loading coil, I explain exactly how that happens
on my web page through the superposition of the forward and reflected
currents. For the typical base-loaded or center-loaded shortened
mobile antenna, If+Ir at one end of the coil is NOT equal to If+Ir
at the other end of the coil even if the two currents through the
coil are of constant magnitudes. I have explained that multiple times
here with no disagreement.

For typical standing-wave antennas with loading coils:
The forward current through a loading coil is reasonably constant.
The reflected current through a loading coil is reasonably constant.

The two above facts are obeying Kirchhoff's laws.

The total current is the sum of the forward current and the reflected
current and results in a cosine function standing wave on the antenna.
The differing phases of forward current and reflected current is what
causes the variation in the total current, i.e. the current drop.

The current drop in a standing wave antenna is similar to the current
drop in a section of transmission line with reflections. The governing
equations can be found in any EM textbook and for lossless situations
are of the form:

Itot = If*e^-yz - Ir*e^+yz

Losses to radiation or I^2*R add another couple of e^-2ad (attenuation)
terms.
--
73, Cecil http://www.qsl.net/w5dxp


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Tom Donaly wrote:
Besides, you missed the point again.

Sorry, I've been out of town for 10 days and haven't read
all the postings. So please bring me up to date. Exactly
what is "the point"?
--
73, Cecil http://www.qsl.net/w5dxp


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Tom Donaly wrote:
you've hit the nail squarely on the head. The validity of
the whole argument boils down to whether or not you can safely neglect
the effects of the physical dimensions of the inductor on the behavior
of the antenna. It looks to me as if you can, but some of the other
fellows on this newsgroup seem to be as much interested in
characterizing Tom Rauch as a rat as they are in verifying some
antenna effects due to the properties of real loading coils.

You guys have completely missed the point. The argument is not about
the behavior of the antenna. The original argument is/was about the
current in a real-world antenna loading coil. The behavior of the
antenna is irrelevant to that original argument.
--
73, Cecil http://www.qsl.net/w5dxp


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Tom Donaly wrote:
I
don't agree with the term "current drop" because, even in a transmission
line, current, or more properly, current density, doesn't act like a
potential of any sort to which you could ascribe a "drop."

Webster defines "drop" as "to become less". Seems to me, the current
"becomes less" as one moves the measurement point from a current loop
to a current node on a standing-wave antenna.
--
73, Cecil http://www.qsl.net/w5dxp


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Tom Donaly wrote:
current, in a wire, is the total current density integrated across
a cross section of the wire. It's a vector, ...

From "Fields and Waves in Communications Electronics", by Ramo, Whinnery,
& Van Duzer, page 239: "It must be recognized that the symbols in the
equations of this article have a *different* meaning from the same symbols
used in Art. 4.06. There they represented the instantaneous values of the
indicated *vector* and scalar quantities. Here they represent the complex
multipliers of e^jwt, giving the in-phase and out-of-phase parts with
respect to the chosen reference. The complex scalar quantities are commonly
referred to as *phasors*, ..."

From the IEEE Dictionary: "The phase angle of a phasor should not be
confused with the space angle of a vector."

You are obviously confusing vectors and phasors.
--
73, Cecil http://www.qsl.net/w5dxp


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Richard Clark wrote:
There is no such Kirchoff law of two separate points of current, that
is Kirchoff's voltage law. A point (singular, the only component of
Kirchhoff's current law) has no dimension, any departure from this
necessarily excludes itself from strict Kirchhoffian analysis.

Yes, you are starting to get it. Point inductances don't exist
in reality.
--
73, Cecil http://www.qsl.net/w5dxp


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On Thu, 21 Oct 2004 00:18:59 -0500, Cecil Moore
wrote:
starting to get it
took you a long time too.

On Wed, 20 Oct 2004 23:44:01 -0500, Cecil Moore
wrote:
behavior of the antenna is irrelevant
sour grapes :-)