So "reality" exists when the software gives you the answer you expect:
http://www.qsl.net/w5dxp/current.htm
but is useless otherwise?

Maybe more like answer that reflects reality?

You trust it to analyze linear conductors
and inductive stubs that have inductance and capacitance per unit
length but conclude that it is flawed when the conductor is coiled up
a bit. Interesting.

Isn't it interesting that loading stubs and coils, having the same inductance
do the same amount of shortening of the wip, same effect, but when modeling
programs model it, they show different current distribution? Funny logic?


What about coax choke used at the antenna feedpoint? Have not heard "reason"
for different RF current at both ends. It chokes, doesn't it? Huh?
Yuri

Wes Stewart wrote:

wrote:
|I will argue about any software package that doesn't agree with reality.

So "reality" exists when the software gives you the answer you expect:

Come on, Wes. Reality exists when the software *accurately* models inductance,
capacitance, and resistance. Software packages that assume zero distributed
capacitance in a real-world coil are simply inaccurate for certain applications.
For instance, Kraus' phase-reversing coil cannot be modeled in EZNEC, at least
not as a single coil in a straight forward manner. Do you have any suggestions
about using EZNEC (or other MOM software) to model the phased array antenna
described by Kraus on page 824 of _Antennas_for_all_Applications, 3rd edition,
which uses two phase-reversing coils?

So the question still stands. Can you model Kraus' phase-reversing coil using
the method of moments? If so, and the coil is not perfectly tuned and perfectly
installed, you will have current flowing into both ends of the coil at the same
time. I am not a MOM expert, so I don't know the answer. EZNEC seems to model
phase-reversing stubs just fine.

You trust it to analyze linear conductors
and inductive stubs that have inductance and capacitance per unit
length but conclude that it is flawed when the conductor is coiled up
a bit. Interesting.

EZNEC seems to model inductive stubs just fine so I have no reason to
distrust it. EZNEC fails to give the same results for an inductive stub
Vs a lumped inductive reactance because it doesn't model real-world
coils. It will not model Kraus' phase-reversing coil and gives erroneous
results when an antenna using phase-reversing coils is modeled. I have
the EZNEC files that demonstrate that fact if you would like to have them.

Did you bother to read Rhea's paper?
http://www.eagleware.com/pdf/apps/20...ngSolenoid.pdf

This is the first I have heard of it. I will read it this afternoon
at work. I can't download .pdf files at home.
--
73, Cecil http://www.qsl.net/w5dxp



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On 29 Jan 2004 13:38:56 GMT, oUsama (Yuri Blanarovich)
wrote:

|So "reality" exists when the software gives you the answer you expect:
|http://www.qsl.net/w5dxp/current.htm
|but is useless otherwise?
|
|Maybe more like answer that reflects reality?
|
|You trust it to analyze linear conductors
|and inductive stubs that have inductance and capacitance per unit
|length but conclude that it is flawed when the conductor is coiled up
|a bit. Interesting.
|
|Isn't it interesting that loading stubs and coils, having the same inductance
|do the same amount of shortening of the wip, same effect, but when modeling
|programs model it, they show different current distribution? Funny logic?
|
|
|What about coax choke used at the antenna feedpoint? Have not heard "reason"
|for different RF current at both ends. It chokes, doesn't it? Huh?


Sorry, I've taken all of the jabs at this tarbaby that I care to. I
spent a lot of time preparing the paper that I published and it
"reflects reality" as I see it, until proven otherwise.

I would think that the pair of you would give a Howard Dean,
Yeeeeaaaaa! yell and claim that my findings proved your point that the
current is different at the two ends of the loading coil. Go figure.

Wes

On Wed, 28 Jan 2004 22:08:40 -0600, Cecil Moore
wrote:

I haven't been paying attention.

Obviously

Danny, K6MHE

Wes Stewart wrote:
Sorry, I've taken all of the jabs at this tarbaby that I care to. I
spent a lot of time preparing the paper that I published and it
"reflects reality" as I see it, until proven otherwise.

What is the name of your paper, Wes? I don't remember you
mentioning it before. All I have seen from your postings is
..pdf files of the work of others.
--
73, Cecil http://www.qsl.net/w5dxp



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Dan Richardson wrote:

wrote:
I haven't been paying attention.

Obviously

The original posting made no assertions and was simply a URL
which didn't respond when I tried to access it. The subsequent
postings seemed to be concerned with radiation resistance so I
didn't even read them. How does radiation resistance affect the
loading coil discussion? It has already been proven that EZNEC's
lumped circuit model doesn't work for Kraus' real world loading
coils. What else is there to say?
--
73, Cecil http://www.qsl.net/w5dxp



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On Thu, 29 Jan 2004 10:00:38 -0600, Cecil Moore
wrote:

|Wes Stewart wrote:
| Sorry, I've taken all of the jabs at this tarbaby that I care to. I
| spent a lot of time preparing the paper that I published and it
| "reflects reality" as I see it, until proven otherwise.
|
|What is the name of your paper, Wes? I don't remember you
|mentioning it before. All I have seen from your postings is
|.pdf files of the work of others.

I began this thread with a pointer to:

http://www.qsl.net/n7ws/Loaded%20antennas.htm

Wes Stewart wrote:
I began this thread with a pointer to:
http://www.qsl.net/n7ws/Loaded%20antennas.htm

Sorry, that page wouldn't load on my computer at the time
so I never read it. I will read it this afternoon. In the
meantime, is there anything in the paper that will defeat
the following argument?

Consider a mobile helical antenna for 75m. Will anyone
assert that the current at the bottom of the antenna is
equal to the current at the tip of the antenna?

Add a one foot stinger and reduce the length of the helical
until it is again resonant. Will anyone assert that the
current into the antenna is equal to the current into the
stinger?

Make the stinger two feet and resonate the antenna. Will
anyone assert that the current into the antenna is equal
to the current into the stinger?

Keep up this iteration until the current into the coil is
equal to the current out of the coil.

At exactly what length of coil does the current taper
magically disappear?
--
73, Cecil, W5DXP

Cecil wrote,

Tdonaly wrote:
Have you ever actually made one of these magical coils, Cecil? If you
have, will you tell me how to do it?

It ain't rocket science, Tom, and it ain't magic. Do you understand self-
resonance? Every coil is self-resonant on some frequency. Build the antenna
for whatever that frequency is. My Diamond 440 MHz mobile antenna uses a
phase reversing coil to phase a 1/4WL element with the 1/2WL element
directly above yielding a fair amount of gain over a single 1/4WL element.

Did you read Wes' material?

That .pdf file locks up my computer during downloading. I may
need an upgrade to my Adobe Acrobat reader.
--
73, Cecil http://www.qsl.net/w5dxp


So any coil that is self-resonant at the antenna's frequency will
do?
73,
Tom Donaly, KA6RUH

Cecil wrote,

EZNEC seems to model inductive stubs just fine so I have no reason to
distrust it. EZNEC fails to give the same results for an inductive stub
Vs a lumped inductive reactance because it doesn't model real-world
coils. It will not model Kraus' phase-reversing coil and gives erroneous
results when an antenna using phase-reversing coils is modeled. I have
the EZNEC files that demonstrate that fact if you would like to have them.


Cecil, you can't even give a coherent explanation of how or why Kraus
"phase reversing coil" works, or how it relates to Wes' work. I would
expect any coil would work between two half-wave dipoles, but maybe not
at the frequencies you expect, and certainly not just because Kraus
said so.
73,
Tom Donaly, KA6RUH