On Thu, 10 Jan 2008 11:25:56 -0800, Jim Kelley
wrote:

the Poynting vector for an RF standing wave has
a magnitude of zero and no direction.

So much for the Poynting vector of a position envelope. What are your
thoughts regarding the Poynting vector for a time varying envelope of
an electromagnetic wave? :-)

Hi Jim,

Imagine even more the dilemma this puts the dipole in! It has
suddenly collapsed into a shielded, dummy load. ;-)

DAMN! Did my TV screen just go blank?

73's
Richard Clark, KB7QHC

On 10 Jan, 11:25, Jim Kelley wrote:
Cecil Moore wrote:
An RF standing wave does not behave like an EM wave
nor does it meet the definition of an EM wave which can be represented
by a Poynting vector. The Poynting vector for an RF standing wave has
a magnitude of zero and no direction.

So much for the Poynting vector of a position envelope. *What are your
thoughts regarding the Poynting vector for a time varying envelope of
an electromagnetic wave? *:-)

ac6xg

Keep going guys. You are nearly at the end. Must be! Richard has
already started on "I knew that all the time" in an effort to take all
the credit. Mohammed has come to the mountain
and found that Richard the bard was already there.LOL
Art Unwin...KB9MZ...XG(uk)

On Jan 10, 1:25 am, Roy Lewallen wrote:
After reading this, I understand why you find Art's material interesting.

But, what's a "wave"?

A wave is any periodic function f(x) where f(x) = amplitude and whose
period X defines one cycle.

wrote:
On Jan 10, 1:25 am, Roy Lewallen wrote:
After reading this, I understand why you find Art's material interesting.

But, what's a "wave"?

A wave is any periodic function f(x) where f(x) = amplitude and whose
period X defines one cycle.

So if we send a single pulse down a transmission line, no wave is
created or exists?

Roy Lewallen, W7EL

AI4QJ wrote:

The single pulse can be decribed by its fourier series a superposition of
sinudoidal waves so you would actually be sending wave(S) down the line, of
varying harmonic frequencies, but only for the time defined by the pulse
width.

So a sine wave consisting of only two cycles is considered a periodic
function? How about one cycle? Half cycle? Does a truncated sine wave
fit the proposed definition of f(x) where x is the period? Would the
pulse then be one wave or an infinite number of waves (since the
spectrum of any time-limited function is infinite in width)?

Wouldn't it be fun to calculate the power in each of the infinite number
of sine waves and add them together like Cecil does to get the total
power? Boy, I'll bet you'd have a *lot*!

Roy Lewallen, W7EL

On Jan 10, 10:55 am, Gene Fuller wrote:
.. You never give up, do you? Even when you are caught in an utter
lie. You
know exactly what the capacitors are for, and it isn't to control
transmission line reflections from open ends of the line.

I'm sorry, Gene, but I cannot alleviate your ignorance with one
posting. Given a voltage phasor and a current phasor with a phase
angle between them, there is absolutely no way to distinguish between
a mismatch and a reflection. The purpose of those power factor
capacitors on the power line poles is to turn those transmission lines
into money-making traveling wave delivery systems rather than allow
money-losing standing wave systems. Please stop your emoting long
enough to realize what I have said is true.

If the capacitors were not there, the inductive loads would cause
reflections just as they do on an RF transmission line. The only
difference is that the 60 Hz transmission line is a small fraction of
a wavelength. If you scaled the 60 Hz system to 6 MHz, all the same
laws of physics would apply and the similarities would be readily
apparent.
--
73, Cecil, w5dxp.com

On Jan 10, 10:59 am, Gene Fuller wrote:
.. It is really amazing that you can make up so many requirements that
are
completely unknown to the rest of the world. Is that a Mensa thing?

Methinks you need to study and comprehend the nature of photons and
photonic waves.
--
73, Cecil, w5dxp.com

On Jan 10, 11:08 am, Jim Kelley wrote:
If you follow this thread back, you will find that you were the one
who wrote "a standing wave is a different kind of electromagnetic wave".

I don't remember saying that and I apologize if I ever did. What I
remember saying is that an RF standing wave doesn't meet the
definition of an EM wave which is essentially the same thing that Dr.
Hecht said: "Standing Waves:....These might better not be called waves
at all since they do not transport energy and momentum."

RF standing waves, unlike other EM waves, do not transport energy and
momentum at the speed of light in the medium. Therefore, they are
technically not EM (photonic) waves.
--
73, Cecil, w5dxp.com

On Jan 10, 2:25 pm, Jim Kelley wrote:
So much for the Poynting vector of a position envelope. What are your
thoughts regarding the Poynting vector for a time varying envelope of
an electromagnetic wave? :-)

If the wire runs in the 'x' direction, the standing wave phasors
rotate only in the 'yz' plane. Since the Poynting vector is always
normal to the E-field and H-field, seems the instantaneous value of
the Poynting vector for a standing wave is still zero.
--
73, Cecil, w5dxp.com

On Jan 10, 2:34 pm, Richard Clark wrote:
Imagine even more the dilemma this puts the dipole in! It has
suddenly collapsed into a shielded, dummy load. ;-)

Sorry, the dipole standing waves are only about 80% of the energy on
the antenna. The other 20% of the energy is radiated (or lost to
heat). If the waves on the 1/2WL dipole were 100% standing waves, the
antenna would have a zero feedpoint impedance, but it doesn't
--
73, Cecil, w5dxp.com
..