Efficient MoM Implementation for Modelling Microstrip Excitations and Loads Avoiding Stub Elements

New models for the excitation and load of planar microstrip circuits are presented in this paper in connection with a numerical analysis based on the Method of Moments (MoM). These new models facilitate a direct computation of the scattering matrix, without the need of a conversion from e.g. an impedance matrix or without the need of adding extra stub elements. In particular for the analysis of radiation from or coupling of different signal traces, these extra stub elements can deteriorate the solution.