A General Coupling Matrix Synthesis Method for All-Resonator Diplexers and Multiplexers

Coupling matrix (CM) synthesis methods for all-resonator diplexers and multiplexers are far from mature. For complex coupling topologies, the existing methods are often not able to find the appropriate CMs that satisfy the S-parameter specifications. To address this challenge, a new synthesis method, which hybridizes analytical and optimization techniques, called general all-resonator diplexer/multiplexer CM synthesis (GACMS) method, is proposed in this article. The two main innovations of GACMS are: 1) an optimization framework incorporating filter design knowledge, which effectively reduces the search space for CM synthesis and 2) a new memetic algorithm-based optimizer, which tackles the challenges from the complex landscape (function characteristics) of CM synthesis problems. GACMS is tested by six complex practical problems and CMs are successfully obtained for all of them. Comparisons with the existing methods demonstrate the advantages of GACMS in terms of solution quality and robustness.