Roy:

[snip]
"Roy Lewallen" wrote in message
...
Thanks for the most interesting discussion of slinkys, "ether", and
seismology. But I'm a little vague on what you mean by "vibrations".
You're describing a field whose orientation isn't necessarily at a right
angle (transverse) to the direction of propagation (as in a TE or TM
mode wave), yet whose "vibrations" are nevertheless at a right angle to
the direction of propagation. So the "vibrations" are in a different
direction than the field. I'd like to learn more about this phenomenon,
but I can't find "vibrations" in the indexes of any of my
electromagnetics texts. Do they have another name?

Roy Lewallen, W7EL
[snip]

Vibrations = oscillations

An instance where compressional-dilative waves might occur in
electromagnetic propagation and where those compressional vibrations terms
could be added to the Maxwell-Heaviside equations might be that of
electromagnetic propagation through "light ion" plasmas [ionized gases]
where the ions could physically respond essentially instantaeously to the
passing waves and the distance between ions and hence the media properties
becomes a function of the electromagnetic fields. The effective mu and
epsilon of the media changing instantaneously in response to the propagating
fields, in turn changing the waves, etc... just as for compression acoustic
wave propagating in a compressible gas. This effect is probably
infinitesimal for "heavy ion" plasmas and might be perceptable for "light
ion" plasmas. I wonder if any readers of this NG have any experience with
propagation in plasmas and can share with us if they use
compression-dilutive terms to augment the Maxwell-Heaviside equations in the
analysis.

I presume that the NEC code that you use in EZNEC to integrate the
Maxwellian equations does not support plasma propagation analysis. Perhaps
someone knows of a version of NEC that does. I'd guess that folks at
Lawrence Livermore and at NASA are interested in such problems. I'd be
curious to know if they use augmented versions of Maxwell-Heaviside
equations.

Another, arcane, far fetched, and impractical example of
compressional-dillutive vibrations in em waves that I can think of could be
imagined as a system wherein em waves travel in a waveguide system where the
dimensions of the system [walls of the waveguide] are such that they can
move in and out instantaneously in response to the passing waves thus
alternately confining and expanding the dimensions of the guide relative to
the wavelength of the passing waves, it might be imagined that such action
could induce a wave shortening and lengthening effect on the passing waves
which is what compression-dillution waves are.

Thoughts, comments?

--
Peter K1PO
Indialantic By-the-Sea, FL.