Abstract: A high quality-factor, tunable radio frequency or microwave resonator is disclosed. The resonator includes one or more microelectromechanical switches positioned along its length. The switches are comprised of metal membrane bridges spanning the microstrip resonator. The bridges are connected to radial stubs that comprise reactive loads. An electrostatic potential differential between the bridge and microstrip resonator causes the bridge to collapse, thereby coupling a radial stub to the microstrip. The imposition of the reactive loads on the resonator causes the resonant frequency to change. Multiple resonators employed in a filter configuration can be variably coupled using microelectromechanical bridges that engage or disengage capacitive air gaps between two microstrip lines, to control filter bandwidth over wide tuning ranges.