Analysis of shielded planar circuits by a mixed variational-spectral method

A general method is proposed for analyzing shielded microstrip transmission line characteristics with finite metallization and multidielectric layers within a quasi-TEM wave approach. This method uses Green´s function for formulating the problem and a variational technique with Fourier transform for obtaining practical solutions. This method allows the accurate determination of the static parameters of the transmission lines with good efficiency as compared to methods available in the literature. Several numerical results are found to be consistent with other theories and experiments. The method is validated with microstrip lines having three dielectric layers of different dielectric materials and thick strips.