Balanced Switchable Bandpass Filter With All-Port Reflectionless and Common-Mode Suppression Characteristics

A novel balanced switchable bandpass filter with all-port reflectionless characteristics is proposed in this paper. The balanced switchable bandpass filter comprises a balanced switchable filtering section with bandpass response and two absorptive networks. The absorptive network proposed in this paper adopts only one structure to achieve both differential- and common-mode reflectionless characteristics. The proposed switchable resonators in the filtering section and the proposed absorption networks excited under even- and odd-modes are analyzed in detail. For the purpose of verification, a prototype is manufactured based on the simulated results, and it has a good consistency. The experimental results exhibit that the proposed balanced bandpass filter exhibits a differential-mode bandpass filtering function and all-port reflectionless performance in the ON-state, differential-mode isolation function, common-mode suppression, and reflectionless behavior in the OFF-state, which verifies the feasibility of the design theory.