Rigorous solution of mode spectra for shielded multilayer microstrip lines

Based on the equivalent transmission line concept, a simplified method has been developed to derive the dyadic Green's functions and field expansion coefficients for multilayer structures. An improved formulation of the singular integral equation method is presented for shielded multilayer microstrip lines. A systematic method for analytically calculating the final characteristic matrix to any order is also proposed. The developed numerical technique leads to an accurate and efficient determination of both propagation constants and field distributions for a large number of eigenmodes. For instance, 100 modes can easily be computed in reasonable CPU time.>