Simple and Accurate Algorithms to Include Lange-and Asymmetric Microstrip Couplers in CAD-Packages

Given equations for two equal coupled microstrip lines, simple but accurate formulas are presented for the more general cases of asymmetric coupled lines and Lange-strapped lines, both with three, and with an even number of conductors. The basis is a quasi-TEM treatment. Accuracy is better than 2 % and finite conductor thickness is included. Methods to calculate loss and dispersion are suggested.