MEMS Based Tunable Microstrip Patch Antenna Fabricated Using Printed Circuit Processing Techniques

Abstract

This thesis presents MEMS-based electrostatically tunable microstrip patch antennas fabricated using printed circuit processing techniques. The microstrip patch is patterned on the top side of a flexible kapton polyimide film, which is suspended above the fixed ground plane using a spacer. The air gap between the microstrip patch and the ground plane is decreased by applying a DC bias voltage between the patch and the ground plane. A decrease in air gap increases the effective permittivity of the antenna resulting in a downward shift in the resonant frequency. The microstrip patch is excited by a slot in the ground plane, which is fed by a coplanar waveguide (CPW) feed line. Square and circular patch designs are presented in this thesis. A 6 mm x 6 mm square microstrip patch antenna tunable from 18.34 GHz at 0 V to 17.95 GHz at 268 V (with a tuning range of 390 MHz) is presented. A second design, a 6 mm diameter circular microstrip patch antenna tunable from 16.91 GHz at 0 V to 16.64 GHz at 165 V (with a tuning range of 270 MHz) is also presented. The important feature of the tunable microstrip patch antenna presented here is that it is suitable for fabrication using proven printed circuit processing techniques such as photolithography, wet, and dry etching techniques. These new tunable microstrip antennas are inexpensive as well as versatile and are suitable for implementation of a large inexpensive tunable reconfigurable RF front end, tunable reflect array, etc..