TSSP: List Archives

From: Paul
Date: Sat, 26 May 2001 14:08:03 +0100
Subject: Re: [TSSP] Loss due to ultrasonic mechanical vibration of

> >Not too clear on it myself. I think the coil tries to expand,
> >and the mechanical vibration would be at 2 times the RF frequency.

Terrell W. Fritz wrote:

> I would think the frequency is equal, not two times but...

If the force is outwards regardless of the direction of the current,
then the force waveform will be shaped like the rectified current
waveform, with its main component at 2*Fres. This rectification
also means that there will also be a component at the modulation or
envelope frequency, thus making things potentially audible.

> >You're right, I think the forces could be calculated, but I don't
> >know how to go on to calculate the movement and energy loss.
 
> F=MA, V=FT (?) and all the physics stuff I forget at the moment. But
> that is all for freely moving objects as opposed to wire imbedded in
> poly...

Hmm, seem to remember learning that stuff a couple of decades ago.
Thinking about it, might not be too hard to get a rough idea. Symmetric
radial outwards force, some guess at the elasticity would get you
in idea of the displacement, but how to come up with a loss?

As usual, not enough hours in the day.  Another item to add to the
ever growing list of open questions.

Cheers,
--
Paul Nicholson,
Manchester, UK.
--


Maintainer Paul Nicholson, paul@abelian.demon.co.uk.