Fast direct electromagnetic optimization of a microwave filter without diagonal cross-couplings through model extraction

An efficient and fast method for the electromagnetic optimization of passive microwave devices is proposed. The method is based on the extraction of a circuital model using identification of rational polynomials that fit the device response. The technique is used to optimize a fourth order L-band filter, formed by reentrant cavity resonators with just straight couplings between them implemented as irises and probes. The filter configuration allows the existence of one transmission zero located at a finite frequency without requiring diagonal cross couplings. The optimization procedure achieves a reduction of the number of electromagnetic analysis that makes possible the use of the finite element method in a design and optimization loop obtaining the final design in a reduced amount of time.