A methodology was presented in the Dec. 1996 issue of the
IEEE Transactions on Microwave Theory and Techniques that
allows modeling of interconnects with frequency-dependent
parameters. The authors are M. Celik and A. Cangellaris.
One of the examples is for a line with frequency dependent
R and L.
The methodology has been implemented in a prototype code
using Berkeley SPICE. Of course, as it was pointed out
by Ray Anderson, one needs to provide data for the
frequency-dependent p.u.l. parameters.
Please contact me if you need any further information or
a copy of the aforementioned paper.
University of Illinois at Urbana-Champaign
1406 West Green Street
Urbana, IL 61801-2991