On Jan 13, 11:23*pm, "Frank" wrote:
Frank, I am not saying he is not credible but he is part of the older
generation and there was not enough detail supplied to determine
whether I accept it on trust. When the antenna programs
throw out the yagi in favor of arrays or radiators in equilibrium form
should we throw it out in favor of conforming with the past? Yes,the
article is in line with what the older generation has lived with
but the new generation have more tools and information than the
present dying generation.
Problem with present day authors is *up against the "publish or
perish" format regure references to prior papers in quantity to
provide legitamacy to any new papers, without which they will have a
hard time publishing. Greasing the wheels of fellow contributers or
white paper authors is much preferable to declaring those who judge
are in error. Frank, a lot of the theory of antennas is either based
on vanishingly thin radiators without regard to room required for eddy
field and in some cases with transmission lines where it is possible
to get three different current flows together with a closed circuit,
yet we are now protecting the idea of non closed circuits where the
current flow
is on top of each other. No wonder it is said over the last 100 years
that we don't fully understand radiation especially when it takes over
70 posts on how to make a cantenna from a panel of experts
Best regards
Art

I would hardly call the tools used in this simulation "Older".
Ansoft produces some of the most sophisticated, and up to
date FEM software available. *I have seen Ansoft's HFSS
accurately model current flow through PCB vias, around an end-
launch connector at 20 GHz. *CST Microwave also
produces high end FEM software. *All the models are
done in full 3 D, with actual physical dimensions. *This
FEM software started to apear about 10 years ago and
costs in the range of $40,000 to $50,000, with a $10,000
per year maintenance fee.

"Publish or perish" is usually applied to university positions.
It is doubtfull that too many people are able to pubish in
the Proceedings of the IEEE, or one of the IEEE Society
Transactions.

Frank,
It has not yet been proven that current does not flow thru the center
of a radiator.
I see it as a manufactured statement to satisfy the idea of an
uncompleted circuit where the current
passes over or thru and in a different direction than the same current
that generates its existence !
It does all this where the books state it is a series circuit where
the paths taken by the current are not identical. Why manufacture all
these happenings to prove what is just a theory, while at the same
time destroying the reasoning of a closed circuit without an
explanation how such actions
creat radiation, especially when it is admitted that radiation is not
fully understood?
I think the time as come to review again from the time of Maxwell and
build up afresh in line with
a century of findings and then re evaluate.
A good start would be to evaluate why antenna programs based on
Maxwells laws provide solutions based on equilibrium while discarding
all other designs. Saying that it can't be! Because" "if true it
would have been discovered a 100 years ago" while silently adding "all
is known about antennas and the patent offices should be closed"
Regards
Art

Jim Kelley wrote:
Dave wrote:
"Art Unwin" wrote in message
...

( I am assuming that skin depthg is not limitless.)
of course it is limitless, it is an exponential function so it never
goes to zero. the so called 'skin depth' is only the point where the
current has dropped to 1/e or about 37% of the surface value, still a
significant current.

The plots at the link Frank provided show current going rather abruptly
to zero - even negative ("contrary"?) in some cases. I wouldn't
presume to know whether it is modeled correctly.


Decrease of RF current with depth below the surface of a conductor is
only a true exponential if the available conductor depth is infinite.
In the modeled situations where there is 'competition' from a skin
effect on the opposite side of the conductor, the solution is a Bessel
function which does pass through zero and reverse direction at certain
depths.

In other words, the model is behaving as expected.

Programs such as NEC and Maxwell are not released until they have gone
through a very detailed process of checking and validation. The first
step is to check against special cases that can be independently solved
by analytical methods (in other words, pure math). The work isn't
complete until all the results agree within close margins, and the
reasons for any differences are fully understood.

By the time we amateurs come to hear about these programs, they have
already been thoroughly validated by developers and professional users.
That doesn't make them immune from further criticism... but only by
people who have done the work to earn that right.


--

73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek

On Jan 14, 2:46*am, Ian White GM3SEK wrote:
Jim Kelley wrote:
Dave wrote:
*"Art Unwin" wrote in message
...

( I am assuming that skin depthg is not limitless.)
*of course it is limitless, it is an exponential function so it never
goes to zero. *the so called 'skin depth' is only the point where the
current has dropped to 1/e or about 37% of the surface value, still a
significant current.

The plots at the link Frank provided show current going rather abruptly
to zero - even negative ("contrary"?) in some cases. *I wouldn't
presume to know whether it is modeled correctly.

Decrease of RF current with depth below the surface of a conductor is
only a true exponential if the available conductor depth is infinite.
In the modeled situations where there is 'competition' from a skin
effect on the opposite side of the conductor, the solution is a Bessel
function which does pass through zero and reverse direction at certain
depths.

In other words, the model is behaving as expected.

Programs such as NEC and Maxwell are not released until they have gone
through a very detailed process of checking and validation. The first
step is to check against *special cases that can be independently solved
by analytical methods (in other words, pure math). The work isn't
complete until all the results agree within close margins, and the
reasons for any differences are fully understood.

By the time we amateurs come to hear about these programs, they have
already been thoroughly validated by developers and professional users.
That doesn't make them immune from further criticism... but only by
people who have done the work to earn that right.

--

73 from Ian GM3SEKhttp://www.ifwtech.co.uk/g3sek

So the developers know why the programs in the final analysis
gyrate towards radiators and arrays in equilibrium?
Do you know what that reason is?
Present thinking, I thought, suggest that the skin depth is quite thin
when used
for non destructive testing of materials. Is that also known by the
developers?
If the providing current is on the surface of a radiator then why does
the resulting eddy current
penetrate to the limits? Seems a sort of scrambled assumptions at play
here!

What diametric ratio must a fractional wave length radiator be to
allow contrary current flow thru it's center. ?
Diameter / wavelength = 1.0, 0.5, 0.1. 0.001, 0.0001,
0.00001,...?
Regards
Art

That depends on your return on investment in cost and labor, and the
application. Since the skin effect applies, thankfully, the flow through
the center is less of an issue.

Should we use tubular elements?

Or as some have done, use Silver or Copper plated steel wire or rod? At
some frequencies, this is profitable.

Why should we "allow contrary current flow through it's center." as opposed
to promoting the skin effect, since current flow through the center does not
radiate? Like eddy currents in a transformer are just loss.

On Jan 14, 10:13*am, Art Unwin wrote:


So the developers know why the programs in the final analysis
* gyrate towards radiators and arrays in equilibrium?

I don't see how they could, being you won't describe how the
word "equilibrium" applies in such a case.

Do you know what that reason is?

Being I have never seen an antenna modeling program gyrate,
whether towards or away from a radiator or array, I sure don't.

Frank, I am not saying he is not credible but he is part of the older
generation and there was not enough detail supplied to determine
whether I accept it on trust. When the antenna programs
throw out the yagi in favor of arrays or radiators in equilibrium form
should we throw it out in favor of conforming with the past? Yes,the
article is in line with what the older generation has lived with
but the new generation have more tools and information than the
present dying generation.
Problem with present day authors is up against the "publish or
perish" format regure references to prior papers in quantity to
provide legitamacy to any new papers, without which they will have a
hard time publishing. Greasing the wheels of fellow contributers or
white paper authors is much preferable to declaring those who judge
are in error. Frank, a lot of the theory of antennas is either based
on vanishingly thin radiators without regard to room required for eddy
field and in some cases with transmission lines where it is possible
to get three different current flows together with a closed circuit,
yet we are now protecting the idea of non closed circuits where the
current flow
is on top of each other. No wonder it is said over the last 100 years
that we don't fully understand radiation especially when it takes over
70 posts on how to make a cantenna from a panel of experts
Best regards
Art

This is so amusing. Those who don't appreciate knowledge thus far, probably
don't know it. Those who are desperately hoping for a revolution might just
have a ulterior motive or agenda.

It is interesting to note though, that it takes a lot of PhD's to design
something so that impoverished people (often children) can have a bowl of
rice every day to build the technology. Also, the environmental disaster
that is created by throwing away "gadgets" every 6 months to implement the
latest technology. I wonder if the Liberal academic establishment is in
touch with the environmental disaster they are creating so that we can all
be enslaved to the global neural network.

The cantenna posts are amusing, in that no one even brought up the
transition from the connector to the resistor element, or adequate thermal
conductivity between the oil and the outside air. The biggest problems
revolves around these issues. Starting with how long must the transition be
to allow adequate oil convection flow. The answer to all this can be found
with the high power Bird loads that have a smaller oil area but use large
radiating fins, or better yet, A chip resistor array directly mounted to a
large fin area.

On Jan 14, 10:39*am, "JB" wrote:
What diametric ratio must a fractional wave length radiator be to
allow contrary current flow thru it's center. ?
Diameter / wavelength = 1.0, * *0.5, *0.1. * * 0.001, * * *0.0001,
0.00001,...?
Regards
Art

That depends on your return on investment in cost and labor, and the
application. *Since the skin effect applies, thankfully, the flow through
the center is less of an issue.

Should we use tubular elements?

Or as some have done, use Silver or Copper plated steel wire or rod? *At
some frequencies, this is profitable.

Why should we "allow contrary current flow through it's center." as opposed
to promoting the skin effect, since current flow through the center does not
radiate? *Like eddy currents in a transformer are just loss.

Right JB.
If it didn't flow thru the center one could assume that it would
radiate. Thus
keeping the current flow on the outside allows us to use micro length
antennas
since radiation occurs all the time. Whow
If one sees the current flowing thru the center where the losses are
small then one can deduce
that radiation is conmensurate to length up to a maximum of one
wavelength.
By golly isn't that the same solution that the books advocate without
the invention of a circuit that flows when the circuit is abruptly
terminated.
Newton's laws advocate equilibrium as an absolute. Maxwell followed
this absolute when formulating his laws. Application of Gaussian law
of statics by using the eddict of equilibrium
confirms the laws of Maxwell. Antenna programs that are allowed to
follow the edicts of Maxwells laws again substantiate the edict of
equilibrium.
So with all of the above I am inclined to trust such computor programs
but NOT the atributions
supplied to explain the conditions that theories atribute to the
explanation of why agreement is shown with respect to equilibrium plus
the mathematics involved in all the above cases.
I do not know of any other accepted circuit in physics where a circuit
is abruptly terminate and still meet the requirement of equilibrium.
When it is broadly agreed that radiation is not fully understood
when following existing explanations I am inclined to question the
theories

Note Antenna programs with optimizer allows the user to initially
insert a design for a particular requirement and the program will make
corrections to that design by the application of Maxwells laws to
achieve the required object by a solution that is in equilibrium.
Programs WITHOUT an optimizer provides an answer based only on the
metrics inserted and without correction
I.E insert a planar design and the results arrived at reflects the
input only and not the array that completely follows Maxwell which
provides for superior results which never is a planar design
Best regards
Art Unwin....KB9MZ.... xg (uk)
Now to shovel the snow wbhere it is very, very cold.

"JB" wrote in message
...

Frank, I am not saying he is not credible but he is part of the older
generation and there was not enough detail supplied to determine
whether I accept it on trust. When the antenna programs
throw out the yagi in favor of arrays or radiators in equilibrium form
should we throw it out in favor of conforming with the past? Yes,the
article is in line with what the older generation has lived with
but the new generation have more tools and information than the
present dying generation.
Problem with present day authors is up against the "publish or
perish" format regure references to prior papers in quantity to
provide legitamacy to any new papers, without which they will have a
hard time publishing. Greasing the wheels of fellow contributers or
white paper authors is much preferable to declaring those who judge
are in error. Frank, a lot of the theory of antennas is either based
on vanishingly thin radiators without regard to room required for eddy
field and in some cases with transmission lines where it is possible
to get three different current flows together with a closed circuit,
yet we are now protecting the idea of non closed circuits where the
current flow
is on top of each other. No wonder it is said over the last 100 years
that we don't fully understand radiation especially when it takes over
70 posts on how to make a cantenna from a panel of experts
Best regards
Art

This is so amusing. Those who don't appreciate knowledge thus far,
probably
don't know it. Those who are desperately hoping for a revolution might
just
have a ulterior motive or agenda.

It is interesting to note though, that it takes a lot of PhD's to design
something so that impoverished people (often children) can have a bowl of
rice every day to build the technology. Also, the environmental disaster
that is created by throwing away "gadgets" every 6 months to implement the
latest technology. I wonder if the Liberal academic establishment is in
touch with the environmental disaster they are creating so that we can all
be enslaved to the global neural network.

The cantenna posts are amusing, in that no one even brought up the
transition from the connector to the resistor element, or adequate thermal
conductivity between the oil and the outside air. The biggest problems
revolves around these issues. Starting with how long must the transition
be
to allow adequate oil convection flow. The answer to all this can be
found
with the high power Bird loads that have a smaller oil area but use large
radiating fins, or better yet, A chip resistor array directly mounted to a
large fin area.


-------------


What is truly saddening to me is the amount of philosphy/religion that
creeps into these so called scientific discussions. No wonder antenna
modeling is still mostly an art form and not a science.

Ed, N2ECW

Art Unwin wrote:

So the developers know why the programs in the final analysis
gyrate towards radiators and arrays in equilibrium? Do you know what
that reason is? Present thinking, I thought, suggest that the skin
depth is quite thin when used for non destructive testing of materials.
Is that also known by the developers? If the providing current is on
the surface of a radiator then why does the resulting eddy current
penetrate to the limits? Seems a sort of scrambled assumptions at play
here!

Well, at least the last sentence was correct.


--

73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek

Ian White GM3SEK wrote:
Jim Kelley wrote:
Dave wrote:
"Art Unwin" wrote in message
...


( I am assuming that skin depthg is not limitless.)
of course it is limitless, it is an exponential function so it never
goes to zero. the so called 'skin depth' is only the point where the
current has dropped to 1/e or about 37% of the surface value, still a
significant current.

The plots at the link Frank provided show current going rather
abruptly to zero - even negative ("contrary"?) in some cases. I
wouldn't presume to know whether it is modeled correctly.


Decrease of RF current with depth below the surface of a conductor is
only a true exponential if the available conductor depth is infinite. In
the modeled situations where there is 'competition' from a skin effect
on the opposite side of the conductor, the solution is a Bessel function
which does pass through zero and reverse direction at certain depths.

In other words, the model is behaving as expected.

Programs such as NEC and Maxwell are not released until they have gone
through a very detailed process of checking and validation. The first
step is to check against special cases that can be independently solved
by analytical methods (in other words, pure math). The work isn't
complete until all the results agree within close margins, and the
reasons for any differences are fully understood.

By the time we amateurs come to hear about these programs, they have
already been thoroughly validated by developers and professional users.
That doesn't make them immune from further criticism... but only by
people who have done the work to earn that right.

Hi Ian,

Please know that my comment was never intended as a slight of anyone's
work. I simply don't presume to know anything about it other than to
observe that the citation appears to contradict the assertion that skin
depth is limitless and exponential in real conductors.

73, ac6xg