Analysis of single and coupled microstrip lines on anisotropic substrates using differential matrix operators and the spectral-domain method

A differential matrix operator technique is presented to simplify the formulation of boundary-value problems for open millimeter-wave integrated circuits that use anisotropic substrates. The spectral-domain method is applied to analyze the propagation characteristics of single and coupled microstrip lines printed on anisotropic substrates whose properties are described by both [∈] and [μ] tensors. In addition to considering the permittivity and permeability as a uniaxial or biaxial tensor, the effects of coordinate misalignment between the principal axes of [∈] and those of the structure in the transverse plane are also included. It is shown that the misalignment in [∈] and the presence of the [μ] tensor have a significant effect on the dispersive properties of these two structures