Contrary current flow within a radiator
 

On Jan 14, 12:07*am, Art Unwin wrote:

It has not yet been proven that current does not flow thru
the center of a radiator.

Assuming that significant r-f current exists at the center of a
radiating conductor, where does it go when it reaches the end of that
conductor?

RF

Contrary current flow within a radiator
 

Richard Fry wrote:
On Jan 14, 12:07 am, Art Unwin wrote:

It has not yet been proven that current does not flow thru
the center of a radiator.

Assuming that significant r-f current exists at the center of a
radiating conductor, where does it go when it reaches the end of that
conductor?

RF


It doesn't "go" anywhere. As the conductor (and it's return path;
ground or whatever) is resonant, the generator sees it as a resistor.
The current is "absorbed" by this "load". But instead of pure heat, an
electromagnetic field ensues. Nothing goes anywhere.

Contrary current flow within a radiator
 

Richard Clark wrote:
On Wed, 14 Jan 2009 16:29:33 -0500, Michael Coslo
wrote:

Ed Cregger wrote:

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.
So right, Ed. Last time I checked, antennas did not have either a
liberal or conservative bias.

*** observing nothing technically redeeming in this thread ***

We need a new Punchinello, don't you think?

- 73 de Mike N3LI -

Contrary current flow within a radiator
 

On Thu, 15 Jan 2009 09:45:05 -0500, Michael Coslo
wrote:

*** observing nothing technically redeeming in this thread ***

We need a new Punchinello, don't you think?

Hi Mike,

Too true, instead we have a Howdy Dodat.

73's
Richard Clark, KB7QHC

Contrary current flow within a radiator
 

On Jan 15, 7:35*am, Dave wrote:
Richard Fry wrote:
On Jan 14, 12:07 am, Art Unwin wrote:

It has not yet been proven that current does not flow thru
the center of a radiator.

Assuming that significant r-f current exists at the center of a
radiating conductor, where does it go when it reaches the end of that
conductor?

RF

It doesn't "go" anywhere. *As the conductor (and it's return path;
ground or whatever) is resonant, the generator sees it as a resistor.
The current is "absorbed" by this "load". *But instead of pure heat, an
electromagnetic field ensues. *Nothing goes anywhere.

Methinks you are playing games, current doesn't move but charges do
Very devious
Art

Contrary current flow within a radiator
 

Richard Fry wrote:
On Jan 14, 12:07 am, Art Unwin wrote:

It has not yet been proven that current does not flow thru
the center of a radiator.

Assuming that significant r-f current exists at the center of a
radiating conductor, where does it go when it reaches the end of that
conductor?


Ahh.. the famous "boundary condition"..

Say you've got a big bar 100 feet long and a foot in diameter, and
you've induced a rf current along it by some means. All those equations
with the Bessel functions tell you the magnitude and phase of the
current in some infinitely thin slice in the middle.

But, at the end, those equations don't hold. Essentially, the "reverse
current" flows radially across the end and forms part of the "forward
current" on the surface.

I doubt there is a good analytical solution of this. There's probably
some decent approximations (within 5% or something), but anyone who
really cares is going to do a FEM analysis of some sort and solve the
problem numerically.


RF

Contrary current flow within a radiator
 

On Jan 15, 3:48*pm, Jim Lux wrote:
Richard Fry wrote:
On Jan 14, 12:07 am, Art Unwin wrote:

It has not yet been proven that current does not flow thru
the center of a radiator.

Assuming that significant r-f current exists at the center of a
radiating conductor, where does it go when it reaches the end of that
conductor?

Ahh.. the famous "boundary condition"..

Say you've got a big bar 100 feet long and a foot in diameter, and
you've induced a rf current along it by some means. *All those equations
* with the Bessel functions tell you the magnitude and phase of the
current in some infinitely thin slice in the middle.

But, at the end, those equations don't hold. *Essentially, the "reverse
current" flows radially across the end and forms part of the "forward
current" on the surface.

I doubt there is a good analytical solution of this. *There's probably
some decent approximations (within 5% or something), but anyone who
really cares is going to do a FEM analysis of some sort and solve the
problem numerically.

RF


Hmmmm

I think anybody with a education could apply vectors to a full wave
RESONANT radiator with charge and applied current such that Newton's
laws can be shown as being satisfied
Why would anybody shy away from that since we know that there is no
current/ charge flow
on the inside so the vectors will balance. Is there any disagreement
with that aproach.
If so why?
It WILL show agreement with the groups aproach with respect to zero
current / charge flow in the center of a radiator which should make
you all feel good.
Art


Art

Contrary current flow within a radiator
 

Art wrote:
"Frank, It has not yet been proven that current does not flow through
the center of the radiator."

It definitely has been proven that significant current does not
ordinarily flow through the center of a radiating conductor.

Skin effect is an accepted and observed phenomenon.

An RF conductor has a radial E-field, its lines terminating on its
surface. Also, the current carrying conductor has has an H-field whose
lines encircle it. The E-field lines are not exactly
perpendicular to to the conductor`s surface but inclined at a slight
angle to it. The surfaces of equal phase are cupped inward slightly on
the forward side as if the wave were dragging its feet along the
conductor`s surface. The H lines are parallel to the conductor`s
surface. Direction of propagation of the energy is at right angles to
both the E and H fields, but not quite parallel to the conductor`s
surface. It is inclined slightly toward the inside of the conductor.
Direction of propagation can be indicated by a vector P. P can be
resolved into two components, PL and PR . PL represents the longitudinal
component of vector P. PR represents the small amount of energy which is
being drained away from the transmitted signal and dissipated as heat in
the conductor. Radial E lines of force tilted forward in propagation
along the conductor are slowed and short-circuited by the conducting
material through which they are moving. This current flowing through the
resistance of the conductor causes I squared R losses. It also gives
rise to a magnetic field within the conductor which opposes the external
H field.

The result of the above is that the density of the current is quite high
at the copnductor`s surface, diminishing as we look inward toward the
center. The relative phase of the current, in addition, is not the same
at all depths; because of the slow velocity of propagation of the wave
within the conductor, the phase of the current is progressively delayed
as we examine it at greater depths. At some depth, the phase of the
current may be 180 degrees behind that of the surface current, which
means that it is flowing in the opposite direction! The integral of the
current density, integrated over the entire cross-sectional area of the
conductor, will of course be equal to the current in the conductor as
would be read by an ammeter.

Not all conductors are solid copper or aluminum. Seawater has been
thoroughly inveatigated in regard to communication with submarines.
Actual RF currents at all depths have been calculated and measured.

Best regards, Richard Harrison, KB5WZI

Contrary current flow within a radiator
 

Dave wrote:
Richard Fry wrote:
On Jan 14, 12:07 am, Art Unwin wrote:

It has not yet been proven that current does not flow thru
the center of a radiator.

Assuming that significant r-f current exists at the center of a
radiating conductor, where does it go when it reaches the end of that
conductor?

RF


It doesn't "go" anywhere. As the conductor (and it's return path;
ground or whatever) is resonant, the generator sees it as a resistor.
The current is "absorbed" by this "load". But instead of pure heat, an
electromagnetic field ensues.

Yes, it's like asking where does the current go in a real big capacitor.
Charge flows onto and off of the conductors, and since they're
physically large, time is required for the change in field to propagate
from one end to the other. We calculate the current flowing along
antenna elements. But we can also calculate a current flowing through
the aether based on the same principles. Perhaps knowing the magnitude
of the field traveling the element would be at least as useful as
knowing the magnitude of the current. The two are after all
inextricably liked.

Nothing goes anywhere.

Indeed. I like it. It's leads me postulate further that nothing goes
everywhere; anything goes nowhere; everything goes anywhere; anything
goes everywhere; nothing goes nowhere; or perhaps even that everything
goes nowhere.

ac6xg

Contrary current flow within a radiator
 

On Thu, 15 Jan 2009 14:53:32 -0800 (PST), Art Unwin
wrote:

I think anybody with a education could apply vectors to a full wave
RESONANT radiator with charge and applied current such that Newton's
laws can be shown as being satisfied

Education?

Vectors?

Laws?

This is tales from the crypt of dead white scientists. I already
showed two ways to DO IT - who needs to go to a library? Only gurus
and those who dress like them.

73's
Richard Clark, KB7QHC