Pneumatically switched microwave and antenna structures

The concept of switching microwave structures that interact with propagating electromagnetic waves using pneumatic techniques is studied in this paper. The pneumatic actuation is achieved using a toggling of air pressure and vacuum to separate or unite the metallic poles of the switching elements. Pneumatic actuation can be applied across a broad area such as a metamaterial surface, or at a localized point as a switching or shorting element. In this paper, pneumatically actuated metallic patches are applied to microstrip patch antennas for the first time. It is shown that the pneumatic actuation can tune the resonant behavior of the patch antenna and even switch the mode of feeding without the need for applied DC bias. The pneumatic cell itself is non-metallic, hence it does not greatly interfere with the electromagnetic operation of the microwave structure.