The Rigorous Analysis of Strongly Coupled Step Discontinuities in Microstrip

A rigorous formulation for the analysis of strongly coupled step discontinuities in boxed microstrip is presented. Use is made of a variational method in which the transverse E field at the discontinuity is expanded in a suitable set of basis functions. Strongly coupled steps are analysed using the concept of "localised" and "accessible" modes and making use of a multi-port network model. Results are presented for the double step discontinuity.