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

ABSTRACT 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.