On Tue, 15 May 2007 22:02:56 -0500, (Richard
Harrison) wrote:

On page 253 of the 3rd edition of "Antennas" is
Figure 8-32. For certain coils it shows velocities exceeding the speed
of light.

Hi Richard,

The velocities of what?

73's
Richard Clark, KB7QHC

Richard Clark, KB7QHC wrote:
"The velocities of what?"

Figure 8-32 labels the ordinate values as "relative phase velocity".
Phase velocity is defined in my electronic dictionary as:
"The velocity at which a point of constant phase is propagated in a
progressive sinusoidal wave."

In other words, pick a point on a waveform. The rate at which it moves
is phase velocity. That`s the velocity of propagation.

Best regards, Richard Harrison, KB5WZI

On Wed, 16 May 2007 08:43:03 -0500, (Richard
Harrison) wrote:

In other words, pick a point on a waveform. The rate at which it moves
is phase velocity. That`s the velocity of propagation.

Hi Richard,

The velocity of an imaginary point that contains no information nor
energy.

73's
Richard Clark, KB7QHC

Richard Clark wrote:
'The velocity of a point that contains no information nor energy."

The topic of "phase shift" relates to alternating electrical current,
that is volts and amps. These are essential to energy and they are
represented by symbols which are manipulated to solve our problems. A
sinusoidal wave is the symbol of the periodic variation of electrical
properties with time. Volts and amps taken in-phase represent real
energy.

All points on a sinusoidal traveling wave move with the same velocity
past a fixed point. So, to determine the velocity of the motion, choice
of a particular point on the wave, be it zero or peak value, no matter
where the wave travels, or how attenuated, is always the zero or peak
value of the alternation. For velocity, choice of the particular point
to use is immaterial.

The symbol of the wave contains the information. The wave itself
contains the energy.

Best regards, Richard Harrison, KB5WZI

On Wed, 16 May 2007 10:57:58 -0500, (Richard
Harrison) wrote:

Richard Clark wrote:
'The velocity of a point that contains no information nor energy."

What I in fact said was:
The velocity of an imaginary point that contains no information nor
energy.
in response to:
In other words, pick a point on a waveform. The rate at which it moves
is phase velocity. That`s the velocity of propagation.

My response is still valid in science and technology. Richard, if you
choose to challenge this, cite an explicit reference that says Phase
Velocity contains information and energy. Further demonstrate how
your accrual of these characteristics on Phase Velocity does not then
change it to Group Velocity. It is Group Velocity that propagates
information and energy.

73's
Richard Clark, KB7QHC

Richard Clark, KB7QHC wrote:
"The velocity of an imaginary point contains no information nor energy."

You could imagine a point like that. I regret omitting the word
"imaginary". It was unintentional.

I gave a dictionary definition of "phase velocity". It seems to be
synonymous with propagation velocity. The same dictionary defines group
velocity, and says:
"Group velocity differs from phase velocity in a medium in which the
phase velocity varies with frequency."

If phase variation with frequency is severe, and if the signal contains
multiple frequencies, I think it would likely alter the waveform.

Best regards, Richard Harrison, KB5WZI

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.

Best regards, Richard Harrison, KB5WZI

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

Richard Clark wrote:
On Wed, 16 May 2007 08:43:03 -0500, (Richard
Harrison) wrote:


In other words, pick a point on a waveform. The rate at which it moves
is phase velocity. That`s the velocity of propagation.


Hi Richard,

The velocity of an imaginary point that contains no information nor
energy.

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

ac6xg

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.

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

73's
Richard Clark, KB7QHC