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 4
^th
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.