Development of shape memory alloy actuator integrated flexible poly-ether-ether-ketone antenna with simultaneous beam steering and shaping ability

Active control of antenna radiation by mechanical reconfiguration has large potential applications in space as well as in ground segment. Such reconfigurable antenna primarily has two functionalities: beam steering and beam shaping. While previous research has shown individual control of these functions; we have developed a suitable antenna actuation system which takes care of both the functionalities. To demonstrate our concept, we have fabricated a 1-m diameterC-band flexible reflector of poly-ether-ether-ketone using precisely machined aluminum mold. A periphery feed structure is connected to the center of the reflector by a goose-neck-shaped supporting frame. Next, we have designed and developed a smart control-disk containing two types of shape memory alloy actuator-based self-locking devices. A group of actuators are used for locking/unlocking the rotational degree of freedom of the antenna; while the other group generates deformation of antenna at the desired direction. An 8-bit absolute encoder is installed with each locking device to sense and feedback the displacement of a control point. We have achieved a controllable deflection up to 25 mm with a precision of 0.3 mm with this system. A directional precision of 0.2 degrees is also achieved simultaneously. Presently, we have developed eight such actuation points on the disk to control the shape of the antenna. For numerical simulation of the structural deformation and study of the radio frequency pattern, finite element analysis is carried out using ABAQUS, and the far-field radiation pattern corresponding to the deformed shape is obtained. The electromagnetic patterns are analyzed using geometric optics technique. Finally, a methodology of achieving surface coordinates for desired radiation pattern is presented. The study provides useful insights into the design of flexible and reconfigurable antenna system.