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Old April 23rd 09, 05:26 PM posted to rec.radio.amateur.antenna
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On Apr 23, 4:42*pm, Jim Kelley wrote:

For a more quantitative illustration of how distributed reactance in
transmission lines causes delay seehttp://www.rhombus-ind.com/dlcat/app1_pas.pdf

73, ac6xg


Jim, thanks for the reference.

Perhaps I should have expressed myself more clearly. What I've not
seen, for example, is a lumped-element analysis which takes just the
coil dimensions as input, and predicts theoretically - without a lot
of empirical "tweaking" - the reactance at a particular frequency;
particularly a frequency close to self-resonance. There may be one out
there, but I've not yet found it!

In contrast, the ON4AA calculator - based on Corums' transmission-line
analysis - does just that, and produces results which seem to match
well the EZNEC modelling results.

Regards,
Steve G3TXQ

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Old April 23rd 09, 06:49 PM posted to rec.radio.amateur.antenna
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On Apr 23, 11:26*am, steveeh131047 wrote:
On Apr 23, 4:42*pm, Jim Kelley wrote:



For a more quantitative illustration of how distributed reactance in
transmission lines causes delay seehttp://www.rhombus-ind.com/dlcat/app1_pas.pdf


73, ac6xg


Jim, thanks for the reference.

Perhaps I should have expressed myself more clearly. What I've not
seen, for example, is a lumped-element analysis which takes just the
coil dimensions as input, and predicts theoretically - without a lot
of empirical "tweaking" - the reactance at a particular frequency;
particularly a frequency close to self-resonance. There may be one out
there, but I've not yet found it!

In contrast, the ON4AA calculator - based on Corums' transmission-line
analysis - does just that, and produces results which seem to match
well the EZNEC modelling results.

Regards,
Steve G3TXQ


That is because the transmission line is considered to be within a
arbitrary boundary
where all applicable forces equals zero, ie in equilibrium. Eznec is
also based on the condition of equilibrium as applied by Maxwell in
concert with Newton.
This group is using the conditions accounted on this Earth where as
scientific laws are based upon a Universe within a boundary and not
just the Earth. TRhat is equivalent to saying weight is the same
metric as mass !
Art
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Old April 23rd 09, 07:34 PM posted to rec.radio.amateur.antenna
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steveeh131047 wrote:
On Apr 23, 4:42 pm, Jim Kelley wrote:
For a more quantitative illustration of how distributed reactance in
transmission lines causes delay seehttp://www.rhombus-ind.com/dlcat/app1_pas.pdf

73, ac6xg


Jim, thanks for the reference.

Perhaps I should have expressed myself more clearly. What I've not
seen, for example, is a lumped-element analysis which takes just the
coil dimensions as input, and predicts theoretically - without a lot
of empirical "tweaking" - the reactance at a particular frequency;
particularly a frequency close to self-resonance. There may be one out
there, but I've not yet found it!

In contrast, the ON4AA calculator - based on Corums' transmission-line
analysis - does just that, and produces results which seem to match
well the EZNEC modelling results.

Regards,
Steve G3TXQ


EZNEC is a mathematical model just as the transmission line model is
a model. EZNEC doesn't use a transmission line
analog in order to reach its conclusions. If you're really interested
in this subject, you have to read Schelkunoff and others who did the
research on this years ago. A big, honking loading coil doesn't
act much like a lumped component. It makes a pretty shabby transmission
line, too. If you want to understand it, you have to study
electromagnetics and approach it from that standpoint, which may not
be easy. Finally, a modest question: if you have EZNEC, why would you
be wasting time with something inferior? The gold standard is the gold
standard. Or are you on some philosophical quest, like Cecil?
73,
Tom Donaly, KA6RUH
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Old April 23rd 09, 08:53 PM posted to rec.radio.amateur.antenna
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On Apr 23, 1:34*pm, "Tom Donaly" wrote:
steveeh131047 wrote:
On Apr 23, 4:42 pm, Jim Kelley wrote:
For a more quantitative illustration of how distributed reactance in
transmission lines causes delay seehttp://www.rhombus-ind.com/dlcat/app1_pas.pdf


73, ac6xg


Jim, thanks for the reference.


Perhaps I should have expressed myself more clearly. What I've not
seen, for example, is a lumped-element analysis which takes just the
coil dimensions as input, and predicts theoretically - without a lot
of empirical "tweaking" - the reactance at a particular frequency;
particularly a frequency close to self-resonance. There may be one out
there, but I've not yet found it!


In contrast, the ON4AA calculator - based on Corums' transmission-line
analysis - does just that, and produces results which seem to match
well the EZNEC modelling results.


Regards,
Steve G3TXQ


EZNEC is a mathematical model just as the transmission line model is
a model. EZNEC doesn't use a transmission line
analog in order to reach its conclusions. If you're really interested
in this subject, you have to read Schelkunoff and others who did the
research on this years ago. A big, honking loading coil doesn't
act much like a lumped component. It makes a pretty shabby transmission
line, too. If you want to understand it, you have to study
electromagnetics and approach it from that standpoint, which may not
be easy. Finally, a modest question: if you have EZNEC, why would you
be wasting time with something inferior? The gold standard is the gold
standard. Or are you on some philosophical quest, like Cecil?
73,
Tom Donaly, KA6RUH


Tom,TomTom.
Eznec DOES use the transmission line analogy because like Gauss it
uses an abitrary border where the contents are in equilibriumn or in a
state of balance where all forces are accounted for when a time
varying field is applied. The same goes for a transmission line where
the radiation factor is also accounted for.
The radiation force losses are accounted for by the depreciating
impedance with time
which is also shown by the deprecating amplitude of occilation where
each period loss of amplitude represents radiation energy. If the
amplitude showed no change then you have a tank circuit without
friction or other losses. No losses means perpetual motion and vica
versa. If on Earth friction is always there which is also equal to the
energy for an acceleration of a particle. On the reverse side, a
deccelerating force on a particle represents kinetic energy as opposed
to the potential energy supplied for radiation where the product is
seen as light. As with a light bulb radiant heat is what we know as
light. Just classical physics no less
Art
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Old April 23rd 09, 09:06 PM posted to rec.radio.amateur.antenna
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On Apr 23, 7:34*pm, "Tom Donaly" wrote:
Finally, a modest question: if you have EZNEC, why would you
be wasting time with something inferior? The gold standard is the gold
standard. Or are you on some philosophical quest, like Cecil?


Tom,

Yes I have EZNEC and recognise what a great tool it is. Its
predictions were the benchmark against which I tested the various coil
models I read about, and no-one has yet suggested that it can't be
trusted for modelling a helix.

I'm not on some "philosophical quest" - I'm just an old, retired, guy
who still likes learning and wants to understand more about how things
work; I hope that never leaves me! I stumbled on this discussion quite
by chance and tried to understand the various "positions" being taken.
Perhaps I'm over-simplifying, but it seemed to me there was a group
who favoured the transmission-line model and a group against it. I've
tried dispassionately to understand the various arguments and to form
my own conclusions.

Now here's my problem:

* The results I get using a model based on transmission-line analysis
are very close to my EZNEC predictions - not perfect, but way better
than any lumped-element analysis results
* I don't see quantitative, non-empirical, arguments being put forward
to support lumped-element analysis
* I see numeric arguments being put forward by Cecil to support a
transmission-line approach - they look convincing to me and, although
I see a lot of unpleasant personal attacks on him, I don't see any
scientific challenge to his figures
* On the other hand I see folk whose work I rate highly, seemingly
willfully to misunderstand some of the points which Cecil puts forward

Please don't think I'm trying to defend Cecil - I wouldn't be so
presumptuous, and anyway he's old enough to look after himself! I'm
just trying to understand why, what seems to me to be such a
persuasive argument, generates such opposition. Either there's some
glaring technical error here which I haven't yet spotted, or perhaps
there's a long "history" between various "personalities" of which I'm
ignorant?

Still confused,

Steve G3TXQ


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Old April 23rd 09, 10:09 PM posted to rec.radio.amateur.antenna
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steveeh131047 wrote:


Tom,

Yes I have EZNEC and recognise what a great tool it is. Its
predictions were the benchmark against which I tested the various coil
models I read about, and no-one has yet suggested that it can't be
trusted for modelling a helix.

I'm not on some "philosophical quest" - I'm just an old, retired, guy
who still likes learning and wants to understand more about how things
work; I hope that never leaves me! I stumbled on this discussion quite
by chance and tried to understand the various "positions" being taken.
Perhaps I'm over-simplifying, but it seemed to me there was a group
who favoured the transmission-line model and a group against it. I've
tried dispassionately to understand the various arguments and to form
my own conclusions.

Now here's my problem:

* The results I get using a model based on transmission-line analysis
are very close to my EZNEC predictions - not perfect, but way better
than any lumped-element analysis results
* I don't see quantitative, non-empirical, arguments being put forward
to support lumped-element analysis
* I see numeric arguments being put forward by Cecil to support a
transmission-line approach - they look convincing to me and, although
I see a lot of unpleasant personal attacks on him, I don't see any
scientific challenge to his figures
* On the other hand I see folk whose work I rate highly, seemingly
willfully to misunderstand some of the points which Cecil puts forward

Please don't think I'm trying to defend Cecil - I wouldn't be so
presumptuous, and anyway he's old enough to look after himself! I'm
just trying to understand why, what seems to me to be such a
persuasive argument, generates such opposition. Either there's some
glaring technical error here which I haven't yet spotted, or perhaps
there's a long "history" between various "personalities" of which I'm
ignorant?

Still confused,

Steve G3TXQ


There aren't many people who would support a lumped-element analysis on
this newsgroup. Most people know the limitations of using network theory
in these circumstances. The technical arguments against Cecil's approach
were offered a long time ago. This latest is just a flareup that will
soon die down. You shouldn't be confused. The transmission line model of
antennas is well accepted and hoary with age, particularly for
bi-conical antennas (see Schelkunoff). There are a couple of other types
of models with equal validity. If you really want to know the physical
score, though, you have to get an electromagnetics text that discusses
the integral equations that govern antenna behavior. Pay particular
attention to the parts that explain why numerical methods like EZNEC
have to be used for solutions rather than the symbolic math most people
would expect and want.

73,
Tom Donaly, KA6RUH

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Old April 23rd 09, 10:22 PM posted to rec.radio.amateur.antenna
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Tom Donaly wrote:

There aren't many people who would support a lumped-element analysis on
this newsgroup. Most people know the limitations of using network theory
in these circumstances. The technical arguments against Cecil's approach
were offered a long time ago. This latest is just a flareup that will
soon die down. You shouldn't be confused. The transmission line model of
antennas is well accepted and hoary with age, particularly for
bi-conical antennas (see Schelkunoff). There are a couple of other types
of models with equal validity. If you really want to know the physical
score, though, you have to get an electromagnetics text that discusses
the integral equations that govern antenna behavior. Pay particular
attention to the parts that explain why numerical methods like EZNEC
have to be used for solutions rather than the symbolic math most people
would expect and want.

73,
Tom Donaly, KA6RUH


I did and do support lumped element analysis for a very small toroidal
loading inductor, and extensively posted the reasons why in this
newsgroup about six years ago ("Current in antenna coils controversy",
2003). Cecil and Yuri were arguing that the coil would replace some
number of "degrees of antenna" and its current therefore would have a
substantial phase difference between input and output ends. I made and
posted careful measurements to support my statement, after which Cecil
invented his "standing wave current" and went off in various directions.

Roy Lewallen, W7EL
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Old April 23rd 09, 11:39 PM posted to rec.radio.amateur.antenna
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Roy Lewallen wrote:
I did and do support lumped element analysis for a very small toroidal
loading inductor, and extensively posted the reasons why in this
newsgroup about six years ago ("Current in antenna coils controversy",
2003). Cecil and Yuri were arguing that the coil would replace some
number of "degrees of antenna" and its current therefore would have a
substantial phase difference between input and output ends. I made and
posted careful measurements to support my statement, after which Cecil
invented his "standing wave current" and went off in various directions.


I didn't invent "standing wave current". Standing wave
current is what EZNEC displays for standing wave antennas.
Standing wave current is what Kraus describes graphically
on page 464, Figure 14-2, of "Antennas ...", 3rd edition.
Standing wave current is what Ramo and Whinnery describe
mathematically in "Fields and Waves ...".

It has been at least 5 years since I explained why
the phase of the current on a standing wave antenna cannot
be used to determine the delay in a wire or in a coil.
EZNEC, Kraus, Balanis, and Ramo and Whinnery all agree
with me and disagree with you. I explained, 5 years ago,
how the magnitude of the current can be used to calculate
the delay through a coil. All my explanations fell on
deaf ears and you called them gobblygook, or some such.

Once again, most of the current in a standing wave antenna
is of the form,

I = Imax*cos(kx)*cos(wt)

For any given time = t1, the phase of the current all up
and down the antenna does not change with x. The phase
is the same at the feedpoint, at the bottom of the coil,
at the top of the coil, and at the top of the stinger.
The phase of that current cannot be used to calculate
delay in a wire or through a coil.

You once said you were quick to admit a mistake. It has
been 5+ years since you made that conceptual mistake
and you have not admitted it yet.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com
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Old April 24th 09, 12:44 AM posted to rec.radio.amateur.antenna
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Roy Lewallen wrote:
Tom Donaly wrote:

There aren't many people who would support a lumped-element analysis on
this newsgroup. Most people know the limitations of using network theory
in these circumstances. The technical arguments against Cecil's approach
were offered a long time ago. This latest is just a flareup that will
soon die down. You shouldn't be confused. The transmission line model of
antennas is well accepted and hoary with age, particularly for
bi-conical antennas (see Schelkunoff). There are a couple of other
types of models with equal validity. If you really want to know the
physical
score, though, you have to get an electromagnetics text that discusses
the integral equations that govern antenna behavior. Pay particular
attention to the parts that explain why numerical methods like EZNEC
have to be used for solutions rather than the symbolic math most
people would expect and want.

73,
Tom Donaly, KA6RUH


I did and do support lumped element analysis for a very small toroidal
loading inductor, and extensively posted the reasons why in this
newsgroup about six years ago ("Current in antenna coils controversy",
2003). Cecil and Yuri were arguing that the coil would replace some
number of "degrees of antenna" and its current therefore would have a
substantial phase difference between input and output ends. I made and
posted careful measurements to support my statement, after which Cecil
invented his "standing wave current" and went off in various directions.

Roy Lewallen, W7EL


I should have specified a large, solenoidal loading coil such as Cecil
is so fond of using. Cecil has since eschewed his "degrees of antenna"
position, but, for some reason, he keeps claiming your tests on the
small solenoid were wrong.
73,
Tom Donaly, KA6RUH
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Old April 24th 09, 02:11 AM posted to rec.radio.amateur.antenna
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Tom Donaly wrote:
I should have specified a large, solenoidal loading coil such as Cecil
is so fond of using. Cecil has since eschewed his "degrees of antenna"
position, but, for some reason, he keeps claiming your tests on the
small solenoid were wrong.


Yes, I have fine-tuned my concepts over the past 5 years.
What rational person would not adjust their concepts to
match the technical evidence? (It's a rhetorical question.
We all know who refuses to do that.)

Roy's tests were wrong in the sense that they were meaningless
no matter how accurate the readings. Quoting my web page:

"All of the reported conclusions based on loading coil
measurements using the current on standing-wave antennas
are conceptually flawed."
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com


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