Scattering from 3-dimensional discontinuities in microwave transmission lines

A material body with complex constitutive parameter values mu and epsilon located in a stripline, partially filling it, represents a 3-D scattering problem. This problem is solved by the reaction method, yielding the configuration's scattering parameters. An approach is presented in which the scattered fields are expanded in terms of the empty stripline eigenmodes, which are calculated numerically using the finite-element method. These basis modes are then coupled in the volume of the material discontinuity by an application of the reciprocity theorem. An iterative procedure then enables the determination of mu and epsilon from the measured values of the S-parameters.<>