Topology Optimization of Microwave Filters Based on Direct Computation of Poles and Zeros

his work presents an optimization method for coupled-resonators filter topologies relying on the computation of poles and zeros directly from the coupling matrix. The optimizer can therefore iteratively fill the non-zero elements of the coupling matrix, assess the resulting poles and zeros and compare them against the required response. The obtained overall difference between the two sets of roots is hence minimized according to a local strategy. The method has been tested up to 12th order responses implemented by a box section, with successful results. Such optimizer has been also compared with other approaches, revealing generally higher reliability than transverse-prototype optimization while suffering from a slightly slower execution speed.