Modelling of arbitrarily shaped MMIC and hybrid planar circuits with a mixed waveguide model boundary integral method

A novel numerical procedure for analysing discontinuities in MMIC and hybrid planar circuits is proposed. It is based on a combination of boundary elements and a planar waveguide model. Shunt posts are taken into account in the model by explicit modal field expansion. This approach employs fewer nodal points than either the finite-element or boundary-element method and allows the direct determination of the S parameters of circuits. It can effectively be applied to the analysis of generalised discontinuity and multiport configurations involving rectangular, circular or arbitrarily shaped boundaries with metallic or dielectric posts. A number of microstrip discontinuity problems are calculated by this method to demonstrate its efficiency. The proposed technique is validated through comparisons between theoretical and experimental results