Piezoceramic actuated aperture antennae

Recently, it has been demonstrated that aperture antennae can have their performance improved by employing shape control on the antenna surface. The antennae previously studied were actuated utilizing polyvinylidene fluoride (PVDF). Since PVDF is a polymer with limited control authority, these antennae can only be employed in space based applications. This study examines more robust antenna structures devised of a thick metalized substrate with surface bonded piezoceramic (PZT) actuators. In this work, piezoceramic-actuated adaptive antennae of cylindrical-cut shape are studied. When a PZT actuator is attached to the reflector surface, the converse effect develops a bending moment in the structure making the reflectors bend inward or outward. This bending can be employed in antenna beam steering and shaping. In order to effectively construct the antenna, the piezoceramic-actuated antenna surface was modeled using classical curved beam theory and Newton's method. The deflection versus voltage relationship was then experimentally verified, and the resulting far-field radiation pattern was simulated on computer. The results emphasize two major points: firstly, the far-field radiation pattern can be altered in a positive fashion, and secondly the first two radiation modes of the antenna correspond to the first vibration mode shapes of the structure.