Characterization of microstrip discontinuities on multilayer dielectric substrates including radiation losses

A two-dimensional space-domain method-of-moments treatment of open microstrip discontinuities on multi-dielectric-layer substrates is presented. The full-wave analysis accounts for electromagnetic coupling, radiation, and all substrate effects. The technique is utilized to characterize commonly used discontinuities on one and two dielectric layers, and numerical results for step, corner, and T-junction discontinuities are included. On the microstrip conductors, both current components are expanded by rooftop basis functions. Once the current distribution is evaluated, transmission line theory is used to determine the network parameters. Numerical results from this technique demonstrate excellent agreement with measurement and the spectral-domain technique in the case of single dielectric layers