Phase Shift through a 75m Texas Bugcatcher Coil
 

Jim Kelley wrote:
Delays are typically measured using pulses.

Please describe the pulse you intend to use on a
1/4WL long standing-wave antenna.

If I thought that was true, I wouldn't have said what I did.

If the delay through the loading coil in a standing-
wave antenna could be measured in situ, then there
would not be any argument. But maybe I am missing
something. How would you propose to measure the delay
through a loading coil during steady-state for a
standing-wave antenna?
--
73, Cecil http://www.w5dxp.com

Phase Shift through a 75m Texas Bugcatcher Coil
 

Cecil Moore wrote:

Please describe the pulse you intend to use on a
1/4WL long standing-wave antenna.

Kind of a wispy brunette one, about 5'7". What difference would it
make, Cecil? One that is short compared to the delay.

If the delay through the loading coil in a standing-
wave antenna could be measured in situ, then there
would not be any argument. But maybe I am missing
something. How would you propose to measure the delay
through a loading coil during steady-state for a
standing-wave antenna?

When you post a question in that way I gotta wonder what you must
think is going on inside an antenna. What's different about the
'situ' during steady state that causes electromagnetic fields to
propagate differently than at other times?

73, ac6xg

Phase Shift through a 75m Texas Bugcatcher Coil
 

Jim Kelley wrote:
What difference would it
make, Cecil? One that is short compared to the delay.

What difference would it make if the frequency of the
pulse is far removed from the operating frequency?
What difference would it make if the frequency is far
above the self-resonant frequency? What difference
would it make if the inductance is completely
swamped by the capacitance? Shirley, you jest.

What's different about the 'situ' during
steady state that causes electromagnetic fields to propagate differently
than at other times?

They don't propagate differently but how does one separate
the forward wave from the reflected wave on a standing-wave
antenna? If you can do that, you will have solved the
measurement problem.
--
73, Cecil http://www.w5dxp.com

Phase Shift through a 75m Texas Bugcatcher Coil
 

Cecil. W5DXP wrote:
"When 600 inches of wire is coiled into a helix, how can EM waves travel
through that 600 inches of wire faster than it can travel through 600
inches in free space?"

Good question. Maybe it figuratively travels from both ends of the coil
toward the niddle. At one part of the cycle the wave is pushing excess
electrons to one end of the coil while it supplies electron deficient
atoms to the other end. Then the cycle reverses the charge situation at
the ends of the coil. Or maybe the photons do blast off to leap across
the length of the coil. My vision isn`t good enough to see what is going
on inside of the coil`s conductor.

Best regards, Richard Harrison, KB5WZI

Phase Shift through a 75m Texas Bugcatcher Coil
 

Cecil, K5DXP wrote:
"I think we are talking about two different coils."

Yes, that`s now obvious. I only worked with W8JI`s coil, and your
numbers were for the bugcatcher coil.

I showed my work, so if my method was wrong, my results are probably
wrong too. Someone is likely to point out the error in my ways and I`ll
learn something.

Best regards, Richard Harrison, KB5WZI

Phase Shift through a 75m Texas Bugcatcher Coil
 

On Wed, 16 May 2007 14:16:43 -0500, (Richard
Harrison) wrote:

Richard Clark, KB7QHC wrote:
"Richard, if you choose to challenge this, cite an explicit reference
that says Phase Velocity contains information and energy."

I already have in two previous postings in this thread. One quotation
was from Terman and the other was from Lenkurt. Both explained how a
traveling wave tube (TWT) works. It uses velocity modulation of an
electron beam to alter the phase and power of a signal carried by a coil
encircling the electron beam. There`s your information and energy.

Hi Richard,

If anything, these citations that you offer move at speeds
considerably SLOWER than the speed of light and is the whole purpose
of the design of their structure.

It was because of this slow speed that the triode structures of even
lighthouse tubes were abandoned as amplifiers. The electron beam
moves at sub-luminal speed and the helix was designed to not only
accommodate to the phase lag introduced by increasingly significant
time delays, but to synchronize to it by optimally delayed signals
wending along a retarding helix.

Now, do you have actual citations that support Phase Velocity carrying
information and energy at faster than light speeds?

73's
Richard Clark, KB7QHC

Phase Shift through a 75m Texas Bugcatcher Coil
 

On Wed, 16 May 2007 12:00:41 -0700, Jim Kelley
wrote:

Richard Clark wrote:
On Wed, 16 May 2007 09:37:17 -0700, Jim Kelley
wrote:


Why such criticism of a meager geometrical object with such useful
purpose? It seems your expectations may be too high.


Hi Jim,

MY expectations are too high? "With such useful purpose" is
overarching by half.
Perception only. Utility in geometrical abstracts exists completely
independently of ones appreciation of them.

Hi Jim,

Wouldn't it be clearer (as you are one who complains of the lack of
clarity) to simply call this "useful purpose" as Zen?


What has Phase Velocity got to do with anything, and what are its
expectations either high or low?

For the problem at hand (antennas) Kraus uses c = w/k, not dw/dk.
Naturally, he was interested in the velocity with which field lines
move across a point - the speed at which the wave propagates.
VF = v sub p over c, not v sub g over c.

The second part of your
question is unintelligible to me.

As is your response. Throwing equations over the transom doesn't make
them explanations.

73's
Richard Clark, KB7QHC

Phase Shift through a 75m Texas Bugcatcher Coil
 

Cecil Moore wrote:
Jim Kelley wrote:

What difference would it make, Cecil? One that is short compared to
the delay.


What difference would it make if the frequency of the
pulse is far removed from the operating frequency?
What difference would it make if the frequency is far
above the self-resonant frequency? What difference
would it make if the inductance is completely
swamped by the capacitance? Shirley, you jest.

The advantage to using pulses is that they are 'broadband' - they
don't have "A" frequency. The inductance and capacitance of the
system are unaffected by the small signals one impresses upon it.

What's different about the 'situ' during steady state that causes
electromagnetic fields to propagate differently than at other times?


They don't propagate differently but how does one separate
the forward wave from the reflected wave on a standing-wave
antenna? If you can do that, you will have solved the
measurement problem.

The antenna behaves physically in exactly the same way whether or not
it happens to be 'occupied' by waves, standing, sitting, or whatever
during measurement. If you want to know how long it take an
electromagnetic wave to traverse a conductor in any shape or
configuration, you pulse it and measure how long it takes, either to
get from one end to the other, or to be reflected back from the other
end. There are of course dispersion effects, and by studying the
change in the waveshape it is possible to deconvolve the frequency
dependent components. This is a matter of routine for practicioners.

73, ac6xg

Phase Shift through a 75m Texas Bugcatcher Coil
 

Jim Kelley wrote:
The advantage to using pulses is that they are 'broadband' - they don't
have "A" frequency. The inductance and capacitance of the system are
unaffected by the small signals one impresses upon it.

But we are not interested in the phase delay for all
those other frequencies. We are only interested in the
phase delay at one particular frequency. And since we are
talking about distributed networks and not lumped circuits,
the inductance and capacitance of the coil does change with
frequency. Whatever measurements we make need to be made
at the frequency of operation.

The antenna behaves physically in exactly the same way whether or not it
happens to be 'occupied' by waves, standing, sitting, or whatever during
measurement. If you want to know how long it take an electromagnetic
wave to traverse a conductor in any shape or configuration, you pulse it
and measure how long it takes, either to get from one end to the other,
or to be reflected back from the other end.

If the pulse is not at the frequency of operation, the results
are hardly useful at all since the response of the loading coil
is frequency dependent.

So we are back to the original question. How can the delay through
a mobile loading coil be measured at the frequency of operation
in a standing-wave antenna?
--
73, Cecil, w5dxp.com

Phase Shift through a 75m Texas Bugcatcher Coil
 

Richard Clark wrote:

Hi Jim,

Wouldn't it be clearer (as you are one who complains of the lack of
clarity) to simply call this "useful purpose" as Zen?

Hi Richard,

You don't like it much, do you. I suggest not dishing out so much of
it then.

I don't know about you, but I learned about the utility of 'points' in
my geometry and mathematics classes. Data is, for example, often
obtained by accumulating an array of them.

For the problem at hand (antennas) Kraus uses c = w/k, not dw/dk.
Naturally, he was interested in the velocity with which field lines
move across a point - the speed at which the wave propagates.
VF = v sub p over c, not v sub g over c.


The second part of your
question is unintelligible to me.


As is your response.

You probably intended that as a clever retort.

Throwing equations over the transom doesn't make
them explanations.

Had I not 'thrown', you would likely have desired to know what I was
talking about. It was as concise a presentation as I could conjure in
30 seconds. Equations do offer the advantage of illustrating the
point without leaving much need for semantic interpretation.

73, ac6xg