High-Q MEMS-tunable waveguide filters in K-band

This paper presents the first experimental results of innovative MEMS-tunable waveguide filters showing very high Q (>;1000) in K-band. Ohmic RF-MEMS cantilever switches are used to connect printed line sections placed over the side wall of a TE101 mode cavity so realising an equivalent movable inner wall. The effective width of the cavity, thus its resonant frequency, can so be changed by activating the MEMS switches. Such a configuration is shown to yield a frequency tuning range up to 3% with unloaded Qs of the order of 1000 and negligible bandwidth variations (<; 10%). Measurements of a 23 GHz cavity show 730 MHz frequency shift (3.1%) with Qs of 750 and 1450 depending on the MEMS state. K-band 4th order filters have also been designed and fabricated. The experimental results are very promising both in terms of IL (i.e. unloaded Q) and robustness of the filter response after tuning.