Generate Longitudinal Waves?

Question

Is there any pratical way to generate (or utilize) a longitudinal, or Poynting vector, wave?

For example, by establishing a coil geometry, within a non-linear medium, in which the E and B vectors oppose and partially cancel.

If so, what might be the characteristics of such a wave?

Apart from the fringe science crowd, I have seen mainstream references which apparently capitalize technologically on the longitudinal vector, and others claiming it doesn't exist as an independent force.

Any informed opinions?

And a related question, if E and H vectors occur at 90 degrees in a transmitting dipole, can anyone explain how the emitted transverse EM wave becomes in-phase in free space?

Richard Former

Tim Williams · Accepted Answer

Well, Maxwell says such waves don't exist. But space is linear, so = you'll have to be more specific about the nonlinear medium. If you have = an example it might help analysis.

You seem to be comparing a spacial angle with a phase angle, which = doesn't work.

Tim

--=20 Deep Friar: a very philosophical monk. Website:

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whit3rd · Answer

There's lots of wave solutions, to lots of so-called 'wave equations'. The most complex electromagnetic solution I'm aware of is Ewald's treatment of polarizing media (like calcite crystals) which finds a wave solution to a Hertz vector (if memory serves).

I've never known a longitudinal E solution for a wave equation, and if there WERE such a medium, shining normal light onto it would generate a high intensity of surface wave (which violates thermodynamic principles that limit light focus intensity). Or, shining normal light onto it would do something extremely strange (my intensity argument depends on energy density and propogation of energy in the medium, which are only completely defined after we have the medium's full properties).

Generate Longitudinal Waves?

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