Topband: Re: Coax capacitor losses

[Jim Brown]

On Fri, 17 Dec 2004 20:40:09 -0800, Richard (Rick) Karlquist (N6RK) 
wrote:

>You cannot calculate "loss resistance" using only 
>a Smith chart, and the dB/ft loss specs.

But you had better use a Smith chart for at least part of the design work.  
Based on its length and the frequency at which it was used, at least one 
of the attempts at a coaxial "capacitor" I saw described here was long 
enough that it looks far more like a transmission line than a lumped 
circuit element.  I would be surprised if it's the only one.  That doesn't 
make its use invalid, but it does change the design.

Remember -- once the line is longer than about 1/10 wavelength, 
transmission line effects begin to dominate the behavior of the coax. 


Jim Brown  K9YC