Full-wave modal analysis of asymmetric coupled lines using the quasi-symmetric approach

This paper presents the investigation of dispersion parameters for asymmetric coupled microstrip structures by using modal domain integral technique. The original aspect of this work is the introduce of the quasi-symmetric approach in order to leads by Galerkin´s procedure to small-size dispersion matrix and thus reduces the numerical computational effort. For this purpose, a rigorous formulation was developed; trial functions of C and π modes were obtained from the quasi-symmetric case, and thus proposed for the asymmetric case. A comparative study of propagation characteristics with respect electrical and physical parameters demonstrated the limits of the quasi-symmetric model validity due to influence of shielding and metal strips widths difference. The validation of numerical results has been carried out by comparisons with previously accurate published data.