MEMS-based high-Q reconfigurable E-plane filters

This paper presents a new concept for the design of reconfigurable bandpass filters with very high unloaded Q-factor using rectangular waveguide resonators loaded with a reconfigurable E-plane circuit. Ohmic MEMS switches are placed around E-plane metal strips so as to modify the TE₁₀₁ mode resonant frequency, thus the central frequency of the filters. Tuning ranges up to 7% are achieved with unloaded Q-factors over 1000. Preliminary measurements of a 3^rd order bandpass hardwired filter at 10 GHz show 625 MHz frequency shift (6.25%) with unloaded Q-factors above 1000 and small variations of both the filter bandwidth and return loss. The final version using actual RF MEMS is presently under fabrication at FBK.