Wcalc Coupled Stripline Model
S. B. Cohn, "Shielded Coupled-Strip Transmission Line",
IRE Transactions on Microwave Theory and Techniques,
Vol MTT-3, No. 10, October 1955, pp. 29-38.
In the special case where the traces are infinitely thin, the coupled stripline
structure has an exact closed form solution for the even and odd mode impedances.
These solutions are given by Cohn in the above reference. When the traces are not
infinitely thin, Cohn gives a modified expression which is approximate to correct
for the finite thickness.
Conductor losses are determined using Wheelers incremental inductance rule. For low
frequencies, an approximate interpolation function has been used to interpolate between
the DC resistance and the skin effect limited resistance.