A 2 pole 9.6–11.7 GHz band stop filter using analog tuning RF MEMS varactors

A tunable 9.6 GHz to 11.7 GHz bandstop filter is presented. Tuning is done using RF-MEMS structures with analogical capacitance variation, from 25 fF to 225 fF [1]. The filter is a 2 pole design, based on ring resonators coupled on a 50 Ohms micro-strip transmission line. A half-wave line is arranged between the two resonators, to optimize microwave performances with a zero reflection mode, and minimizes the out of band losses. The measured performances are -35 dB of rejection at 9.6 GHz, shifting to -42 dB at 11.7 GHz. The losses below the rejected band are less than -1 dB. This device has also been measured under variable RF power and has shown handling at 6 W.