Phase shifter using defected ground structures with MEMS actuated cavity backing

A MEMS-based control structure consisting of a flexible membrane to actuate ground plane defects is presented. Initial tests were performed with a manually constructed cavity structure placed behind the slot. The cavity depth is increased in discrete intervals and the phase difference determined. Promising results from this experiment led to the application of the membrane itself beneath the ground plane defect. The membrane-backed design allows a continuous generation of phase shift through the variation of the cavity depth. An electrode below the membrane causes a deflection due to an applied electrostatic force, allowing a cavity to form between the membrane and the defect in the ground plane. These cavity-backed designs add negligible loss to the system.