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

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

A good way to check the validity of an EZNEC helix model is to create
the helix by itself, run a wire from one end of the helix to the other
right through the middle of the helix, and put a source in the middle of
the wire. Specify a low enough frequency that the helix will be small in
terms of wavelength. I've found the source reactance to compare quite
favorably with the reactance of the inductance calculated by Reg's
program for the same physical dimensions. The self resonant frequency
comes out quite close, also. The Q should be in the same ballpark,
provided wire loss is included in the model, although radiation will
lower it some in the EZNEC model. (The source resistance with wire loss
set to zero is the radiation resistance. As long as it's much lower than
the resistance with wire loss included, the effect of radiation will be
small. If it's not much lower, reduce the frequency.) As I mentioned
before, 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

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

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