TSSP: List Archives

From: Paul
Date: Fri, 27 Oct 2000 08:37:37 +0100
Subject: Re: [TSSP] Sonotube losses

Terry,

On 2nd Sept you supplied some Q measurements,

Terry wrote:
> Bare Coil
> f1 = 148.3kHz  Q = 57.7
> f3 = 347.87kHz  Q = 33.3
> f5 = 513.76kHz  Q = 20.3

and you mentioned that if the coil was put up on a plastic
bucket the Q went up to 75.

I'm trying to decide whether the steep drop in Q factor at the
higher frequencies which you measured above was due to eddy losses
or to sonotube loss. If the simulator is let loose with a fixed
E-field loss factor (of 0.0139) the expected Q factors and Zin are

 f1  713 ohms, Q 69
 f3  990 ohms, Q 127
 f5  950 ohms, Q 187

I wonder if, when clear of the ground plane, your Q follows
the original falling trend, or the rising trend predicted on
the basis of a constant loss with frequency?

Of course, the answer may be both - eddy losses in the tube!

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


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