# Standing Waves in Cylindrical Cavities.

*Most recent answer: 10/22/2007*

Q:

Hello:

I have two questions on the same subject.

Question 1

Is it possible to have a cavity designed as two concentric conducting cylinders which are separated by a dielectric medium support a standing wave? Assume one possible source of the standing wave comes from background noise.

Question 2

Assuming the above is true, would the standing wave distort from being a sine wave to a fully rectified square wave if imposed upon by an external static magnetic field that lies parallel to the length of the concentric cylinders?

Sincerely,

Michael Maurice

- Michael Maurice

Barre, Vermont, USA

I have two questions on the same subject.

Question 1

Is it possible to have a cavity designed as two concentric conducting cylinders which are separated by a dielectric medium support a standing wave? Assume one possible source of the standing wave comes from background noise.

Question 2

Assuming the above is true, would the standing wave distort from being a sine wave to a fully rectified square wave if imposed upon by an external static magnetic field that lies parallel to the length of the concentric cylinders?

Sincerely,

Michael Maurice

- Michael Maurice

Barre, Vermont, USA

A:

#1 Yes, it’s a well know problem in electricity and magnetism. The solutions are combinations of Bessel functions, rather messy things. The addition of a dielectric medium can be handled as well. Yes, they can be excited by background noise if it is properly coupled into the cavity.

#2 No, a static magnetic field has no effect on the solutions.

LeeH

Answer #2 above assumes that the magnetic field has no effect on the dielectric properties of the medium. Usually that’s a decent approximation./ Mike W.

#2 No, a static magnetic field has no effect on the solutions.

LeeH

Answer #2 above assumes that the magnetic field has no effect on the dielectric properties of the medium. Usually that’s a decent approximation./ Mike W.

*(published on 10/22/2007)*