Re: [SI-LIST] : Transmission Line Conductors

Richard Wheeler (richard@wheeler.com)
Fri, 19 Sep 1997 19:51:37 -0700

alterra@adnc.com wrote:
>
> In response to Hans' assertion that one can always ignore permeability at

...........

> I don't know of any analytical code that can handle this problem directly
> and produce a time domain model although one can certainly solve the problem
> at a number of discrete frequencies to create a freqeuncy domain model.
> Some SPICE codes allow one to input tabular frequency domain data and then
> do a time domain simulation.
>
> I hope this is helpful. (...and if anyone has any kovar permeability data
> vs frequency, please let me know)
>
> ---------------------------------------------------------------
> Eric Wheatley Ph.D. (760) 942-9426 (phone)
> Alterra Technology Co. (760) 942-2366 (fax)
> Encinitas, CA 92024 alterra@adnc.com
> ---------------------------------------------------------------

Eric,

I don't know of any existing code that solves the multiple material
problem either. Dr. Bidyut Sen (Sun Micro) and I have used a technique
that was a modification of that explored in the article ....

Time-Domain Skin-Effect Model for Transient Analysis of Lossy
Transmission Lines. Proceedings of the IEEE, VOL. 70, NO. 7, JULY 1982,
pp750-757.

We modeled the different permeability materials as concentric shells of
resistors and inductors selected for the different skin depths and knee
frequencies. The model is simple and intuitive and works in both the
frequency and transient domains of any flavor of SPICE. Our simulation
results were very close to the measurements we made. You might try this
technique until commercial code is developed that handles this difficult
problem.

Best Regards,

Dr. Richard L. Wheeler, President
Wheeler Enterprises