Reconfigurable split rings based on MEMS switches and their application to tunable filters

It is shown that radiofrequency micro-electromechanical-system (RF-MEMS) switches are useful to implement electronically reconfigurable split ring resonators (SRRs). Three different combinations of cantilever-type ON/OFF capacitive switches with SRRs are studied for the design of tunable or switchable SRR-loaded metamaterial transmission lines. These structures are then applied to the design of reconfigurable band stop and band pass filters at the X-frequency band. Through electrostatic actuation of the switches, the resonance frequency of SRRs can be shifted and, as a result, filter bandwidth and/or central frequency can be digitally controlled. Good agreement between theory and experiment is achieved.