Discrete tuneable dielectric resonator for microwave applications

We present a novel approach for discrete frequency tuning of dielectric resonators based on electromechanical actuators such as MEMS. The concept is based on the intermodal coupling between the TE_01δ mode of a cylindrical dielectric resonator and radially arranged planar slotline resonators. The resonance frequency of the dielectric resonator is changed by switching a resistive load at the open end of each quarter wave slotline resonator leading to a variation of the coupling between the slotline resonator mode and the TE_01δ mode of the dielectric resonator. As the consequence the resonance frequency of the TE_01δ mode changes. Based on this novel tuning concept discrete tuning by 5 MHz in 0.25 MHz frequency steps was demonstrated for a test resonator at 2 GHz. The unloaded quality factor is about 10.000 and the measured switching time is about one millisecond.