Synthesizing Microwave Resonator Filters

A study was conducted to demonstrate the synthesis methods for dual-passband microwave resonator filters. The study presented a procedure of an optimization method for synthesizing dual-passband microwave filters that are unable to be synthesized, using analytic methods. The study also demonstrates each step of the optimization procedure for synthesizing microwave dual-passband filters. It is shown that the result from a frequency transformation technique provides better initial values for optimization methods. It is observed that the synthesis procedure uses the conventional low-pass-to-bandpass frequency transformation, similar to the synthesis procedure for narrow-band bandpass filters with a single passband. It is also demonstrated that the synthesis procedure is adequate for the filter whose entire bandwidth is narrow, as compared with the center frequency.