skin depth (eddy current/Foucault currentO)
 

At 3 times the standard depth of skin depth the density is 5 percent
of that on the surface, below which only copper losses with respect to
a time varying current. So what exactly forces a time varying current
to take an alternate route of travel from the center of a conductor
when the resistance is so low compared to other routes that could be
taken.?
Note : center resistance is lower than that on the surface because
skin depth (opposing eddy currents) cannot form.
Art

skin depth (eddy current/Foucault currentO)
 

Art Unwin wrote:
... So what exactly forces a time varying current
to take an alternate route of travel from the center of a conductor
when the resistance is so low compared to other routes that could be
taken.?
Note : center resistance is lower than that on the surface because
skin depth (opposing eddy currents) cannot form.
Art

I think that question is probably best answered with a question(s) ...

What is a thin element?; What is a thick element? What is the surface
area of the element(s) in question?; what are the power densities
involved?; Does the surface quality of the element cause these
measurements to vary?; In all cases ever recorded, is it ALWAYS the
level you gave, i.e., no anomalies?

I have always thought 1/4 copper tubing with a tenalized SS welding wire
of heavy gage though its center was superior at high power, a lot get by
with much thinner elements. On 10m and lower, I would, generally, use
heavy wall copper pipe of 1/2", or so ... on wifi antennas, I use 1/8
heavy wall brass hobby tubing--I suspect no advantage over thin wall.

I would love access to facilities to investigate this, that lacking, I
would love data I could trust ... what do you find so interesting that
rf might be forced deeper into the surface of elements? I assume from
all my readings and studies that rf prefers the surface--the higher the
freq(s) the more the phenomenon is noted/enforced.

Regards,
JS

skin depth (eddy current/Foucault currentO)
 

Art Unwin wrote:
At 3 times the standard depth of skin depth the density is 5 percent
of that on the surface, below which only copper losses with respect to
a time varying current. So what exactly forces a time varying current
to take an alternate route of travel from the center of a conductor
when the resistance is so low compared to other routes that could be
taken.?
Note : center resistance is lower than that on the surface because
skin depth (opposing eddy currents) cannot form.
Art

Babble.

Skin depth and what cause it:

http://en.wikipedia.org/wiki/Skin_depth


--
Jim Pennino

Remove .spam.sux to reply.

skin depth (eddy current/Foucault currentO)
 

On Dec 5, 6:38*pm, John Smith wrote:
Art Unwin wrote:
... So what exactly forces a time varying current
to take an alternate route of travel from the center of a conductor
when the resistance is so low compared to other routes that could be
taken.?
*Note : center resistance is lower than that on the surface because
skin depth (opposing eddy currents) cannot form.
Art

I think that question is probably best answered with a question(s) ...

What is a thin element?; *What is a thick element? *What is the surface
area of the element(s) in question?; what are the power densities
involved?; *Does the surface quality of the element cause these
measurements to vary?; *In all cases ever recorded, is it ALWAYS the
level you gave, i.e., no anomalies?

I have always thought 1/4 copper tubing with a tenalized SS welding wire
of heavy gage though its center was superior at high power, a lot get by
with much thinner elements. *On 10m and lower, I would, generally, use
heavy wall copper pipe of 1/2", or so ... on wifi antennas, I use 1/8
heavy wall brass hobby tubing--I suspect no advantage over thin wall.

I would love access to facilities to investigate this, that lacking, I
would love data I could trust ... what do you find so interesting that
rf might be forced deeper into the surface of elements? *I assume from
all my readings and studies that rf prefers the surface--the higher the
freq(s) the more the phenomenon is noted/enforced.

Regards,
JS

Well John the impedance gets lower as the percent of the wavelength
goes down
Exercising limits when the radiation surface is zero then so is the
radiation
The point I am stating is that a fractional wavelength is less that a
wavelength
and copper losses thru the center is less than an ohm so where is
there a lesser
impedance route fot the current to travel to become a closed circuit
without radiating?
I am just making the point again that antenna knoweledge on this
newsgroup is very sparce
Most do not accept I sq R jn all cases,and most will not accept the
existence of a Faraday cage!
RF does prefer to exist on the surface if and only if contra forces
cannot be over come.
But then "engineers are not scientists" according to one poster so
perusal of white papers is not necessary
as the truth is unimportant. So the single question again........
What is the lowest resistance part from the top of a fractional
wavelength antenna to obtain a closed circuit?
Simple and to the point and no word games as the application of true
true science is indicated to those thus qualified
Art

skin depth (eddy current/Foucault currentO)
 

On Dec 5, 7:01*pm, wrote:
Art Unwin wrote:
At 3 times the standard depth of skin depth the density is 5 percent
of that on the surface, below which only copper losses with respect to
a time varying current. So what exactly forces a time varying current
to take an alternate route of travel from the center of a conductor
when the resistance is so low compared to other routes that could be
taken.?
Note : center resistance is lower than that on the surface because
skin depth (opposing eddy currents) cannot form.
Art

Babble.

Skin depth and what cause it:

http://en.wikipedia.org/wiki/Skin_depth

--
Jim Pennino

Remove .spam.sux to reply.

Good grief. wilkipedia that you refered to is absolutelly correct
I am looking for somebody well vested in RF. If you can point to
an error in the given mathematics text
then you can regain my respect.
Pretty hard to do without a modern college education in physics or
electrical engineering
Next self perceived expert come forward.
Art

skin depth (eddy current/Foucault currentO)
 

Art Unwin wrote:
On Dec 5, 7:01Â*pm, wrote:
Art Unwin wrote:
At 3 times the standard depth of skin depth the density is 5 percent
of that on the surface, below which only copper losses with respect to
a time varying current. So what exactly forces a time varying current
to take an alternate route of travel from the center of a conductor
when the resistance is so low compared to other routes that could be
taken.?
Note : center resistance is lower than that on the surface because
skin depth (opposing eddy currents) cannot form.
Art

Babble.

Skin depth and what cause it:

http://en.wikipedia.org/wiki/Skin_depth

--
Jim Pennino

Remove .spam.sux to reply.

If you can point to
an error in the given mathematics text

What "given mathematics text"?


--
Jim Pennino

Remove .spam.sux to reply.

skin depth (eddy current/Foucault currentO)
 

Art Unwin wrote:

...
Art

I expected someone to pop-in with an ultra-simplistic explanation, and
poof!; Claim the problem explained ...

I myself pay enough attention that, I can see the point you make.
Indeed, anyone with even half-a-brain, interested in rf and having
worked with antennas in a hands-on reality, i.e., build rather than buy,
would have come across this enigma.

Real world example:

I have watched amateurs pump 1+KW into, what I consider, incredibly thin
elements/conductors (my math skills indicate current carrying capacity
of the wire is being vastly exceeded, at points/nodes.) And, it has
struck me that I don't see this element vaporize at a current node!
Indeed, I don't even see a pronounced sag/heating/softening of such
elements ...

The simple/short explanation makes all our "antenna
prophetic/predicting" formulas and equations work ... the long
explanation is a bit more complex, me thinks ...

Regards,
JS

skin depth (eddy current/Foucault currentO)
 

On Dec 5, 8:01*pm, wrote:
Art Unwin wrote:
On Dec 5, 7:01*pm, wrote:
Art Unwin wrote:
At 3 times the standard depth of skin depth the density is 5 percent
of that on the surface, below which only copper losses with respect to
a time varying current. So what exactly forces a time varying current
to take an alternate route of travel from the center of a conductor
when the resistance is so low compared to other routes that could be
taken.?
Note : center resistance is lower than that on the surface because
skin depth (opposing eddy currents) cannot form.
Art

Babble.

Skin depth and what cause it:

http://en.wikipedia.org/wiki/Skin_depth

--
Jim Pennino

Remove .spam.sux to reply.

If you can point to
an error in the given mathematics text

What "given mathematics text"?

--
Jim Pennino

Remove .spam.sux to reply.

What you pointed to as being contrary to what I stated
Silly statement with a liberal smattering of "bable"
does nothing to suggest that you are up to date education in the art.
Next please
Art

skin depth (eddy current/Foucault currentO)
 

Art Unwin wrote:
On Dec 5, 8:01Â*pm, wrote:
Art Unwin wrote:
On Dec 5, 7:01Â*pm, wrote:
Art Unwin wrote:
At 3 times the standard depth of skin depth the density is 5 percent
of that on the surface, below which only copper losses with respect to
a time varying current. So what exactly forces a time varying current
to take an alternate route of travel from the center of a conductor
when the resistance is so low compared to other routes that could be
taken.?
Note : center resistance is lower than that on the surface because
skin depth (opposing eddy currents) cannot form.
Art

Babble.

Skin depth and what cause it:

http://en.wikipedia.org/wiki/Skin_depth

--
Jim Pennino

Remove .spam.sux to reply.

If you can point to
an error in the given mathematics text

What "given mathematics text"?

--
Jim Pennino

Remove .spam.sux to reply.

What you pointed to as being contrary to what I stated

What I pointed to wasn't a "mathematics text" and if it is contrary
to what you stated, that is because your statements are babbling
nonsense.


--
Jim Pennino

Remove .spam.sux to reply.

skin depth (eddy current/Foucault currentO)
 

On Dec 5, 8:09*pm, John Smith wrote:
Art Unwin wrote:

* ...

Art

I expected someone to pop-in with an ultra-simplistic explanation, and
poof!; *Claim the problem explained ...

I myself pay enough attention that, I can see the point you make.
Indeed, anyone with even half-a-brain, interested in rf and having
worked with antennas in a hands-on reality, i.e., build rather than buy,
would have come across this enigma.

Real world example:

I have watched amateurs pump 1+KW into, what I consider, incredibly thin
elements/conductors (my math skills indicate current carrying capacity
of the wire is being vastly exceeded, at points/nodes.) *And, it has
struck me that I don't see this element vaporize at a current node!
Indeed, I don't even see a pronounced sag/heating/softening of such
elements ...

The simple/short explanation makes all our "antenna
prophetic/predicting" formulas and equations work ... the long
explanation is a bit more complex, me thinks ...

Regards,
JS

John., there are one or two who can provide the correct answer.
One is an old timer on this group from years ago who I believe is well
versed in RF
and has made a couple of postings lately. Funny thing is that when an
addition was made to electrical laws by Heaviside
and Maxwell it was just an addition to bring the laws into
equilibrium! Ofcourse, those units encompassed a formula well suited
for a displacement current.
However the idea of waves versus particles exist to this very day even
when Foucualt discovered the presence of a separate current that fit
the initial addition by Maxwell and searched for so long by Einstein
before abandoning classical physics and plunged it to relativism for
the answer on the understanding that the "weak force" was part and
parcel of radiation and a subset of an existing force. He died and
there is nobody left to apply authoritity to his thoughts. I can just
imagine what woild have happened if Einstein extended the static law
by making it a dynamic field which by its equivalent to Maxwell would
have placed particles and equilibrium firmly into radiation. Just
imagine Einstein having possesion of a computer program of today with
optimizer that excluded planar designs in the face of an array in
equilibrium. I know of nobody familiar with the present antenna
programs who can explain the addition of the "'Weak force" that creats
arrays in equilibrium without a hint of parallelism or planar
construction. Have all the antenna computer programmers also died or
do they have a quiet distrust of their work with respect to Maxwell ?
Now we have the relevalation that Neutrinos DO actually have mass
obtained frtom the Sun which puts another nail in the coffin with
respect to waves.
Yes, American Universities deserve their failing grade.( Read Asimov
thoughts on present science teaching)
NEXT engineer scientist/rocket engineer or what ever

Art Unwin KB9MZ....,..,.xg (uk)