Does NEC-2 model wires as solid or hollow?
 

Art wrote:
"For a fractional wave antenna, skin depth or resistance on the surface
does not disappear until the trailing edge of the RF pulse reaches rhe
antenna top."

Assume an open-circuited whip antenna fed with RF. The leading edge of
the first current cycle reaching the antenna tip can continue forward no
farther as it abruptly has run out of conducting parh. It must reverse
directions on the surface of the conductor as it has no where else to
go.

This reversed current is called the reflected current. The reflection is
nearly 100%. I forward plus I reflected add to zero at the open circuit
because they are about equal in magnitude and opposite in phase, caused
by travel in opposite directions.

E forward plus E reflected add to X2 as they are in-phase and of the
same magnitude at the open circuit.

Skin-effect causes both currents, forward and reflected, to ride the
surface of the conductor.

Atenna RF current encounters more inductance in a onductor`s center than
on its surface because there are magnetic force lines inside the
conductor as well as outside encircling its current. Lines inside the
wire only encircle the current beneath them. The exact center of the
wire is encircled by all magnetic lines of force inside and on the
surface of the conductor. It therefore poses the most opposition to RF
current. It is encircled by lines of magnetic force from currents at all
depths in and on a conductor. So, the deeper the current, the more
opposition from inductive reactance to its flow, and that`s the way it
is.

Best regards, Richard Harrison, KB5WZI

Does NEC-2 model wires as solid or hollow?
 

On Jan 8, 11:32*pm, (Richard Harrison)
wrote:
Art wrote:

"For a fractional wave antenna, skin depth or resistance on the surface
does not disappear until the trailing edge of the RF pulse reaches rhe
antenna top."

Assume an open-circuited whip antenna fed with RF. The leading edge of
the first current cycle reaching the antenna tip can continue forward no
farther as it abruptly has run out of conducting parh. It must reverse
directions on the surface of the conductor as it has no where else to
go.

This reversed current is called the reflected current. The reflection is
nearly 100%. I forward plus I reflected add to zero at the open circuit
because they are about equal in magnitude and opposite in phase, caused
by travel in opposite directions.

E forward plus E reflected add to X2 as they are in-phase and of the
same magnitude at the open circuit.

Skin-effect causes both currents, forward and reflected, to ride the
surface of the conductor.

Atenna RF current encounters more inductance in a onductor`s center than
on its surface because there are magnetic force lines inside the
conductor as well as outside encircling its current. Lines inside the
wire only encircle the current beneath them. The exact center of the
wire is encircled by all magnetic lines of force inside and on the
surface of the conductor. It therefore poses the most opposition to RF
current. It is encircled by lines of magnetic force from currents at all
depths in and on a conductor. So, the deeper the current, the more
opposition from inductive reactance to its flow, and that`s the way it
is.

Best regards, Richard Harrison, KB5WZI * * * * *

By golly As I stated before you are correct in your own mind
and I have no intention of changing your attitude as you age.
I acknowledge that we differ in our descriptions but until you provide
scientific proof as opposed to your personal opinion it will continue
to remain that way
regardless.
From now on because of our differences I see no need to respond to
your quotes
Nothing personal intended.
Best regards and farewell
Art
Art

Does NEC-2 model wires as solid or hollow?
 

On Fri, 2 Jan 2009 16:31:08 -0800 (PST), wrote:

Does NEC-2 model "end caps" at free ends, which is equivalent to
assuming wires are solid, or does it just set the current equal to
zero at the free ends, which is equivalent to assuming wires are
hollow? Is it possible that it does both, but the specific model is
determined by the choice of computational kernel (extended vs.
standard)?

This presumes you are seeking a wire that has no current anywhere in
its interior. Clearly there is no such conductor as any conduction
via electrons (or the charge carrier of holes) must circulate about an
atom's nucleus which necessarily imposes an interior current for half
the orbit. The only exemption would be unless the conductor is one
atom thick where there would be no interior. This would then become a
quantum wire which would have problems of its own (called a coulomb
blockade). As such a topic is clearly beyond the scope of discussion
here, for all practical purposes wire is considered to be a bulk, even
for NEC-n and the notion of "end caps" is an artifact of other,
external considerations.

I've tried looking through some of the NEC-2 documentation, but I
can't find a definitive answer.

NEC-n designers are not interested in anticipating the questions to a
vast multitude of speculative scenarios exploring the edges of QED.
For instance, modern economics doesn't provide a definitive answer to
this question either (economists don't really find those same issues
germane either).

* * * * * * * * *

However, this question can be put to any NEC-n modeling package, and
an answer provided quickly with some effort - if you are a skilled
modeler. Further, the same question AND its NEC-n modeled answer can
be weighed at the bench for validity.

At the risk of introducing a practical example that can be tested at
the bench (knowing full well how that can tax the practical skills of
many arm-chair theorists), let's proceed with a simple experiment.

First, we approach the situation with a radiator that is both hollow
AND solid. Yes, a contradiction on the face of it, but explanation
will serve. A coax that is terminated at both ends with female BNC
connections has those ends capped with male shorting plugs. The net
effect is that the "conductor" has two paths, one that is the exterior
shield, and one that is the interior conductor. The shield and
conductor are shorted together at both ends. With such a connection,
we necessarily have a solid.

We drive the exterior shield with a direct connection. Let's simply
make it the vertical radiator against a field of radial ground wires.
To all intents and purposes, the coax is a slightly thickish radiator.
We can physically measure the current excitation along the length of
the exterior path quite simply. When we take the numbers and compare
it to the NEC-n model for a vertical radiator of equal thickness
against a field of radial wires, we find a very close agreement in
results.

NEC-n has been validated in the field.

If we break one of the male shorting caps open to insert a current
meter (replacing the shorting cap with the meter inside the coax);
then we discover there is no practical current inside the coax along
the inner conductor. This should be no mystery as it is a classic
expectation of Freshman physical science. {I will note here for the
purists that I have explicitly stated no "practical" current. There
is no one in this group who could possibly measure the impractical
current.}

To create the NEC-n model would require constructing a cage of wires
to simulate the shield, implanting an interior conductor to simulate
the inner conductor and shorting both ends. This is not a
intellectual leap, merely an hour's worth of careful design. I will
leave it to someone ELSE who cares about the issue to report the
current distribution of that interior wire. A very similar example is
already available at:
http://home.comcast.net/~kb7qhc/ante.../Cage/cage.htm
so complaints of the lack of resources, time, effort, understanding,
and the rest are hollow.

Barring reports to the contrary (and speculation counts for naught),
NEC-n remains validated in the field. I would like to see that
failure demonstrated, but untutored Arthru wholly lacks the skill in
the matter, so I won't hold my breath for his demonstration.

Then the only step that remains is to open the interior wire (in
either/both the physical real model and/or the model) and take new
current distribution numbers. This fully qualifies as an hollow
conductor (you can even remove the interior wire entirely to fully
qualify to the question).

The question is solved through the model without need for browsing
documentation.

If this doesn't serve, then the question wasn't all that important as
an issue in the first place. If this is a serious question, then it
is a necessary test. Barring reports of enumerated results, it then
the question becomes yet another troll. I would note this same test
fully quashes Arthru's speculations of interior currents of a
radiator.

No appeals to Gauss, Newton, Maxwell, or Einstein were necessary in
the production of this posting as results are self evident to the
skilled and naming those dead white scientists are employed only by
hucksters trying to validate patents (aka ego certificates).

73's
Richard Clark, KB7QHC

Does NEC-2 model wires as solid or hollow?
 

Art wrote:
"------in conjunction with my beliefs which shows radiators as not being
parallel with the surface of the Earth where others refused to check in
any way."

I`ve erected countless horizontal antennas. They worked as expected.

I agree that the ionosphere scrambles polarizations so that a distant
signal may have been launched from either a horizontal or vertical
antenna and be received almost as well on an antenna of the other of
those polarizations.

Line of sight propagation is different. The same polarization is needed
for linearly polarized antennas at both ends of a path. This is
experience, not opinion. I`ve experimented with polarization and
optimized countless terestrial microwave paths. I found I could aim dish
elevations with a carpenter`s level and never improve by trying to
adjust for maximum limiter current by refining the polarization
adjustment. The antennas were already parallel at both ends of the path.

Tending to cross-polarize line of sight antennas increases path loss.

Best regards, Richard Harrison, KB5WZI

Does NEC-2 model wires as solid or hollow?
 

"Art Unwin" wrote in message
...
On Jan 8, 11:32 pm, (Richard Harrison)
wrote:
Art wrote:

"For a fractional wave antenna, skin depth or resistance on the surface
does not disappear until the trailing edge of the RF pulse reaches rhe
antenna top."

Assume an open-circuited whip antenna fed with RF. The leading edge of
the first current cycle reaching the antenna tip can continue forward no
farther as it abruptly has run out of conducting parh. It must reverse
directions on the surface of the conductor as it has no where else to
go.

This reversed current is called the reflected current. The reflection is
nearly 100%. I forward plus I reflected add to zero at the open circuit
because they are about equal in magnitude and opposite in phase, caused
by travel in opposite directions.

E forward plus E reflected add to X2 as they are in-phase and of the
same magnitude at the open circuit.

Skin-effect causes both currents, forward and reflected, to ride the
surface of the conductor.

Atenna RF current encounters more inductance in a onductor`s center than
on its surface because there are magnetic force lines inside the
conductor as well as outside encircling its current. Lines inside the
wire only encircle the current beneath them. The exact center of the
wire is encircled by all magnetic lines of force inside and on the
surface of the conductor. It therefore poses the most opposition to RF
current. It is encircled by lines of magnetic force from currents at all
depths in and on a conductor. So, the deeper the current, the more
opposition from inductive reactance to its flow, and that`s the way it
is.

Best regards, Richard Harrison, KB5WZI

By golly As I stated before you are correct in your own mind
and I have no intention of changing your attitude as you age.
I acknowledge that we differ in our descriptions but until you provide
scientific proof as opposed to your personal opinion it will continue
to remain that way
regardless.
From now on because of our differences I see no need to respond to
your quotes
Nothing personal intended.
Best regards and farewell
Art
Art


ain't it great. show him facts and he calls them your opinions and ignores
them... yet question his opinions and you are an old fuddy duddy stuck on
the books that have been good for 100 years.

Does NEC-2 model wires as solid or hollow?
 

Richard Harrison wrote:
Skin-effect causes both currents, forward and reflected, to ride the
surface of the conductor.

Some quantum electrodynamics might help. The electrons
in the conductor are the carriers and move hardly at
all at RF frequencies where electrons can be thought of
as vibrating in place, absorbing and emitting photons.

It is those photons that move at the speed of light and
RF photons cannot travel *inside* a conductor. The cloud
of photons in the space surrounding the conductor is the
same thing as Maxwell's RF electromagnetic field which,
as we assume from conventional physics, cannot exist
deep inside a conductor because of skin-effect.

Seems to me the present argument results from the
confusion between DC steady-state which is electron
flow not involving RF photons and RF "steady-state"
which cannot exist without RF photons.

Photons, unlike electrons, do not have a charge and
thus do not repel each other. Any number of photons
can occupy the same volume including forward and
reflected photons which form the standing wave
surrounding the conductor.

Let's say we have two pieces of coax with a 'T'
connector in the middle. If we short the inside
conductor to the outside conductor on both ends
and apply RF, what would we measure at the
center conductor of the 'T' in the middle?
--
73, Cecil http://www.w5dxp.com

Does NEC-2 model wires as solid or hollow?
 

On Jan 9, 7:10*am, Cecil Moore wrote:
Richard Harrison wrote:
Skin-effect causes both currents, forward and reflected, to ride the
surface of the conductor.

Some quantum electrodynamics might help. The electrons
in the conductor are the carriers and move hardly at
all at RF frequencies where electrons can be thought of
as vibrating in place, absorbing and emitting photons.

It is those photons that move at the speed of light and
RF photons cannot travel *inside* a conductor. The cloud
of photons in the space surrounding the conductor is the
same thing as Maxwell's RF electromagnetic field which,
as we assume from conventional physics, cannot exist
deep inside a conductor because of skin-effect.

Seems to me the present argument results from the
confusion between DC steady-state which is electron
flow not involving RF photons and RF "steady-state"
which cannot exist without RF photons.

Photons, unlike electrons, do not have a charge and
thus do not repel each other. Any number of photons
can occupy the same volume including forward and
reflected photons which form the standing wave
surrounding the conductor.

Let's say we have two pieces of coax with a 'T'
connector in the middle. If we short the inside
conductor to the outside conductor on both ends
and apply RF, what would we measure at the
center conductor of the 'T' in the middle?
--
73, Cecil *http://www.w5dxp.com

Cecil
I wish I could debate with you one on one where there are no snide
remarkes put in place.
Unfortunately my training is as a mechanical engineer where as a ham I
have spread out somewhat into the electrical field and advancing via
the rules of Maxwell and the other masters.
When you move out further with the introduction of protons my eyes
glaze over because I know nothing of such things.
Now this discussion started off with Gauss laws on statics with me
which finally lead to a antenna program that vindicated my stance. It
was the Gaussian aproach that has produced the endless discussion. So
let us put the problem on its head and start with the computer
programs and work backwards. There are two types of antenna
programs.The first type is EZNEC that applies mathematics to pre
designed scenarious which via experience with the books revolve around
planar designes to which it will supply an aswer that one would expect
again via experience from the books and the user is very happy. The
other style of program is an extension of the first where the program
is empowered to modify input dimensions such that the input moves
towards a radiator
that meets the intention of Maxwells laws in their entirety. I use the
latter program where as non of the group will use this type favoring
the basic EZNEC program It is now where we find that it is the details
of the two programs come into evidence. Hams by virtue of their
knowledge and readings
WILL insert a planar design to find the resulting characteristics. On
the other hand I just insert a handfull of numbers and ask the program
to rearrange inserted figures to obtain a certain gain e.t.c.
I can do this as I know that the program based on Maxwells laws will
pursue a line for the best array that meets my request. Now this group
owning only the EZNEC will always insert for a vertical antenna a
design that is at right angles to earth with a specific length of
radiator just like the books they have and it will provide an answer
that the books would expect.
I on the other hand being a mechanical engineer use a program that is
known to reflect the laws of the masters thus it is natural for be to
insert various numbers with no real meaning and leave it to the
experts to rearrange it for the best orientation to meet my request.
So How do these approaches differ.
The group using the EZNEC style of program will input a vertical
antenna at right angles to the Earth wich follows conventional
thinking
I as a mechanical engineer does not assume anything and thus provides
the problem to the program to unravel ie. the numbers provided are
random with respect to orientation.
The results provided is always a vertical that is tipped away from
right angles with respect to Earth.
This presents a paradox two programs providing different results.
Those using the planar aproach and using EZNEC get an orientation that
one sees in the books where-as........
my program which has an optimiser ( the ability to change orientation
in line with Maxwells laws)
provides a orientation of a vertical that is tipped sand supplies
superior results to that of a planar design which it always over rules
in it search for best results.
So the problem is not that the eddy current creats the tipping.
The problem is that a program exists that supplies orientations that
are contrary to those that are generaly in the books used as
tutorial's. Thus the question is a very simple one.
On what grounds can we accept one program that supplies responses that
are not accounted for in tutorial books? One program supplies
solutions that exceed the values supplied by the other,
yet the other program when supplied with the final orientation of an
array or radiator that one program supplied will then show AGREEMENT
with the other program?
Now my reversion to first principles produces disagreement even tho an
alternative approach is not supplied. So as a mechanical engineer I
give the problem to the experts to which there is silence
and an unwilliness to change to an open mind.
So Cecil I presented the facts what two different antenna programs
used in the amateur antenna world supplies and ask, why should I NOT
trust programs that utelize an optimizer aproach based on the laws of
Maxwell and favor a program that use orientations that present
tutorial books supply? A simple question unimpaired by the theories of
particles etc which seems to be a source of annoyance.

My sincere regards
Art Unwin.......KB9MZ.....xg

Does NEC-2 model wires as solid or hollow?
 

Art wrote:
"So Cecil I presented the facts what two different antenna programs used
in the amateur antenna would and ask, why should I NOT trust programs
that utelize the laws of Maxwell and favor a program that use
orientations that present tutorial books supply? A simple question
inspired by theories of particles etc which seems to be a source of
annoyance."

Antenna programs are tools. Their product qualities depend on user
ability as much as upon the tool. Any program telling you to tilt the
tower is wrong for one reason or another. Were that so, after a century
of broadcasting there would be such transmitters and there aren`t.

Particles and EM waves are compatible. I recommend "Electromagnetism and
the Sacred" by Lawrence W. Fagg, ISBN 0-8264-1147-9, which reconciles
QED (Quantum Electromagnetism) and EMI (Electromagnetic Interaction).

Fagg also informs of the Four Forces of Nature. Art said we must account
for "The Weak Force" in our determination, but never said which weak
force he meant.

Fagg says on page 27:
"The strongest of the forces is the nuclear force, which, for example,
keeps the quarks (the most elementary particles that are subject to the
nuclear force) together in clumps of three to form protons and neutrons,
and, in turn, keeps protons and neutrons together in the neucleus of an
atom. Next in order of strength is the electromagnetic force, which is
the fundamental mechanism that makes possible the operation of all
living things including ourselves and most of the material world to
which we relate. The third is known as the weak force, which comes into
play in the radioactive decay of a nucleus and many other elementary
particle phenomena. By far the weakest of the four is gravity.

I won`t bore with more. Read the book.

Best regards, Richard Harrison, KB5WZI

Does NEC-2 model wires as solid or hollow?
 

On Jan 9, 1:00*pm, (Richard Harrison) wrote:
Art wrote:

"So Cecil I presented the facts what two different antenna programs used
in the amateur antenna would and ask, why should I NOT trust programs
that utelize the laws of Maxwell and favor a program that use
orientations that present tutorial books supply? A simple question
inspired by theories of particles etc which seems to be a source of
annoyance."

Antenna programs are tools. Their product qualities depend on user
ability as much as upon the tool. Any program telling you to tilt the
tower is wrong for one reason or another. Were that so, after a century
of broadcasting there would be such transmitters and there aren`t.

Particles and EM waves are compatible. I recommend "Electromagnetism and
the Sacred" by Lawrence W. Fagg, ISBN 0-8264-1147-9, which reconciles
QED (Quantum Electromagnetism) and EMI (Electromagnetic Interaction).

Fagg also informs of the Four Forces of Nature. Art said we must account
for "The Weak Force" in our determination, but never said which weak
force he meant.

Fagg says on page 27:
"The strongest of the forces is the nuclear force, which, for example,
keeps the quarks (the most elementary particles that are subject to the
nuclear force) together in clumps of three to form protons and neutrons,
and, in turn, keeps protons and neutrons together in the neucleus of an
atom. Next in order of strength is the electromagnetic force, which is
the fundamental mechanism that makes possible the operation of all
living things including ourselves and most of the material world to
which we relate. The third is known as the weak force, which comes into
play in the radioactive decay of a nucleus and many other elementary
particle phenomena. By far the weakest of the four is gravity.

I won`t bore with more. Read the book.

Best regards, Richard Harrison, KB5WZI *

Richard you can read therefore you know what the question is. It is
very simple and it is related solely to antenna computor programs that
are used presently around the World. It is understanderble because of
your advanced age you avoid the use of computer. I have no problem
with regard to the proof that you can read but it is not relevent to
the question which you make every effort to avoid. You can venture to
answer the question again based on your computer knoweledge but the
question is based on the veracity of computer antenna programs in use
today and nothing else as the Gaussian aproach appeared to be
confusing. So it makes no use to quote books at this time because I
agree to disagree whith comments based on the Gaussian aproach.
It is for that reason the question is now simplified where it only
encompasing computer programs

Does NEC-2 model wires as solid or hollow?
 

Art wrote:
"It is very simple and it is related solely to antenna computor programs
that are used presently around the World,"

Supposing that Art means: Does NEC-2 model wires as solid or hollow?

It makes no difference. Skin effect makes a hollow wire appear to be
solid.

Computer programs successfully predict antenna performance so they are
in demand the world over as Art noted. They make the tedious easy.

Best regards, Richard Harrison, KB5WZI