A model-order reduction method for the passband and stopband characteristics of periodic structures

A recent 3-D finite element method allows the complex Floquet propagation constant of a periodic structure to be computed at a specified frequency by solving a sparse, generalized eigenvalue problem. To determine the propagation constant for a frequency range requires repeating this eigenanalysis at a large number of frequency points, which is computationally expensive. A model order reduction technique is applied to reduce the dimension of the eigenproblem and to lower considerably the overall computational cost. Results for three 3-D test problems - a metallic cube and two planar structures used in power distribution networks - confirm the accuracy and efficiency of the new method.