MEMS Based Electrostatically Tunable Circular Microstrip Patch Antenna

This paper reports a MEMS based electrostatically tunable circular microstrip patch antenna fabricated using printed circuit processing techniques. The microstrip patch antenna is patterned on the top side of a Kapton polyimide film which is suspended above the ground plane. The resonant frequency of the antenna is tuned electrostatically by applying a DC bias voltage between the patch and the ground plane. The movable patch deflects downward toward the fixed ground plane due to the electrostatic force of attraction caused by the applied DC bias voltage. This deflection decreases the air gap thereby increasing the effective permittivity of the antenna. This increase in effective permittivity results in a downward shift in the resonant frequency. The patch is inductively coupled to a coplanar waveguide (CPW) feed line via a slot in the ground plane. A 6 mm diameter circular patch antenna tunable from 16.91 GHz at 0 V to 16.64 GHz at 165 V, a tuning range of 270 MHz, is presented in this paper