Analytical Calculation of Gradients for the Optimization of H-Plane Filters with the FEM

This paper introduces a method for the analytical calculation of gradients of a cost functions which is an attractive feature when optimizing microwave structures using field solvers. In contrast to utilizing finite differencing all gradients are computed from a single analysis of the structure regardless of its complexity. It is not even necessary to invert a large matrix; a linear system [A]{x}={b} is solved instead. No remeshing is required in the FEM and the gradient values are exact. The basic technique used in this new approach is applied to the optimization of H-Plane filters using the FEM.