A Multi-Parameter Tunable Bandstop Filter Adopting Parallel RF Switch

A multi-parameter tunable bandstop filter was proposed in this letter. The tunable bandstop filter was a parallel structure and mainly constituted of coaxial transmission line, RF switches and tunable resonant - cavities. Unlike the traditional notch points switching based on series RF switch, the parallel RF switch was adopted to realize the number adjust of the notch points. This scheme allows multiple resonators to be connected in parallel on the same transmission line, with the advantage of low passband insertion loss. In order to verify the effectiveness of the method described in this paper, a dual cavity multi parameter tunable notch filter was designed and fabricated, and the test results validated the effectiveness of the proposed scheme.