Optimization of microwave devices using 3-D finite elements and the design sensitivity of the frequency response

Direct optimization of microwave devices is more efficient if sensitivities of the cost function are available. An earlier method for finding sensitivities of the scattering matrix efficiently over a range of frequencies, from a finite-element analysis, is applied here to the optimization problem. The method is tested on rectangular waveguide components with 1-4 design parameters: a right-angle miter bend, an E-plane U-bend, and a waveguide impedance transformer.