Modular Optimization of a Fourth-Order Waveguide Filter With Parallel Coupling Paths

A novel optimization idea is proposed and applied to a fourth-order waveguide filter with two parallel coupling paths between the input and output ports. Since there is no mutual coupling between the two parallel coupling paths, the entire fourth-order filter is decomposed into two subfilters, that is, modules, and the frequency response of each module is separately optimized, which is called modular optimization. According to this idea, modular optimization and traditional overall optimization are implemented on a fourth-order waveguide bandpass filter (BPF) by adopting aggressive space mapping (ASM) for optimization at the start with the same initial parameters. The comparison results show that fewer iterations and higher efficiency can be achieved by using the proposed modular optimization method.