Reconfigurable defected ground microstrip phase shifter using micromachined membranes

摘要

A MEMS based microstrip phase shifter is discussed in this paper. The proposed phase shifter is fabricated in the ground plane beneath a microstrip transmission line. An aperture is first fabricated in the ground plane beneath the transmission line, forming a defected structure. A micro-spring supported thin film copper membrane is fabricated within the aperture, leaving a thin slot surrounding the copper membrane around its perimeter. Slot dimensions define a static phase shift from a normally continuous ground plane. Analog phase shift control is achieved by actuating the flexible membrane away from the transmission line. Simulation results show that for a membrane measuring 1.8 /spl times/ 1 mm in an aperture measuring 2 /spl times/ 2 mm, a phase shift of 25.2/spl deg/ is achieved for a 10 /spl mu/m deflection of the membrane, 30.9/spl deg/ for 50 /spl mu/m deflection, and 32.2/spl deg/ for 100 /spl mu/m deflection.