Just what is a "wave", anyway? Are there different "kinds" of
electromagnetic wave? If so, what are they? Does a "wave" have to travel
in order to be a "wave", or can it just "vibrate" or "oscillate"? Or
just "stand"?

Most of my references call a standing wave a "pattern". Is a "pattern" a
"wave"? Can a "wave" be a "pattern"?

That should be good for another few hundred posts, at least. Sheesh.

Roy Lewallen, W7EL

On Jan 9, 11:22 pm, Roy Lewallen wrote:
Just what is a "wave", anyway? Are there different "kinds" of
electromagnetic wave?

Take a look at the E-field, H-field, and direction of travel for an EM
(photonic) wave. 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.
--
73, Cecil, w5dxp.com

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

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 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
..

On Thu, 10 Jan 2008 17:35:42 -0800 (PST), Cecil Moore
wrote:

dipole standing waves are only about

Ah, yes! The devil is in the "about" where Cecil can prove a new
fundamental law with errors of only 50%. Naturally, we will have to
subscribe to newsletters to find the data. Let me anticipate the next
burst of evidence:
"But you MUST admit that 1 amp through 1 ohm is 1 volt.
Denying this makes you a liar!"

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, 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

Cecil Moore wrote:

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.

A standing wave is an amplitude vs position envelope. An amplitude vs
time envelope is modulation! :-)

ac6xg

On Jan 10, 9:23 pm, Jim Kelley wrote:
A standing wave is an amplitude vs position envelope.

Sorry, that is a false statement. Please reference "Fields and Waves
in Communication Electronics" by Ramo, Whinnery, and Van Duzer, page
343. The equation for the standing wave voltage is: Ez = Efor*e^j(wt-
Bz) + Eref*e^j(wt+Bz)

The equation for a standing wave *envelope* does not contain an
(omega*t) term. The equation for the *standing wave* indeed does
obviously contain (omega*t) terms since the equation for a standing
wave is the sum of the two component traveling waves each containing
an (omega*t) term.

If the (omega*t) term is omitted it is an envelope equation, not a
wave equation.
--
73, Cecil, w5dxp.com