Accurately Approximate Formula of Effective Filling Fraction for Microstrip Line with Isotropic Substrate and its Application to the Case with Anisotropic Substrate

The accurately approximate formula of effective filling fraction q_w is obtained for the microstrip line with zero-thickness strip and isotropic substrate. The line capacitance per unit length C/epsilon₀ for the case with anisotropic substrate can easily be obtained by using the approximate formula of q_w and C₀/epsilon₀ tabulated for the wide range of shape ratio w/h. The parameters Z, v, and lambda for such a line can be calculated by using C/ epsilon₀ and C₀/espsilon₀.