Optimization of passive microwave devices through geometrical parameterization-Application to the design of a cylindrical dual-mode cavity filter

Abstract

A new algorithm, based on geometrical parameterization and finite element method is presented for the optimization of microwave devices. Using geometrical parameterization, the field quantities are expressed as a polynomial in design parameters. Automatic differentiation is used for calculation of higher order derivatives. To ensure continuous gradients, an integrated mesh deformation algorithm is deployed to morph initial finite elements mesh into the perturbed geometry. The resulting parametric model is deployed through quadratic surface reconstruction to find local minimum at each stage. The convergence of the optimization through the reconstructed surfaces is discussed. As an example, a 5-pole dual-mode cavity filter is designed and optimized using the presented algorithm. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.