by Eric Bogatin and Gene Garat, Originally published in EDN Magazine, Feb 19, 2004.  

At clock frequencies greater than 1 GHz and interconnects longer than 12 inches, transmission line loss effects dominate signal integrity. A flexible simulation tool helps you make early trade offs to optimize cost and performance.  Key words: conductor loss, dielectric loss, frequency dependent loss, attenuation, rise time degradation, eye diagrams.