Prev: 4mA current regulator
Next: Small CRT Questions
From: Richard Former on 24 Jun 2010 18:32
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
From: Tim Williams on 24 Jun 2010 19:50
"Richard Former" <richardformer(a)kenlink.com> wrote in message news:4c23d333.399984(a)news.tpg.com.au...
> 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?

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.

> 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?

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

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
From: whit3rd on 25 Jun 2010 17:15
On Jun 24, 3:32 pm, richardfor...(a)kenlink.com (Richard Former) wrote:
> 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.

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).
 | 
Pages: 1
Prev: 4mA current regulator
Next: Small CRT Questions