DESIGN OF AX!-SYMMETRIC DEPLOYABLE REFLECTOR ANTENNA FOR COMMUNICATION SATELLITE

Abstract

Large deployable reflectors are being used increasingly as high gain antenn" systems for satellite communication, radio astronomy and radar surveillance. The requirement for large apertures that can be compactly packaged for launch and reliably deployed in orbit, to achieve their intended configuration precisely, has spurred extensive new research worldwide. In the present report a state of the art review of the deployable reflector antennas is presented. A comparison is made between various reflector antennas in terms of deployed and stowed sizes, mass and accuracy. The design prerequisites for a deployable reflector antenna are formulated. From the above study umbrella type membrane reflector known as Collapsible Rib Tensioned Surface (CRTS) antenna based on the inherent properties of doubly curved surfaces, developed by European Space Agency (ESA) is considered for design and development. The underlying principles, advantages and design methodology of CRTS concept are given. The shape and stress distribution of CRTS reflectors are investigated analytically. The concepts of a reference surface and of an equilibrium surface are given, and programmes are developed to compute. these surfaces and their associated root mean square error. Key geometrical aspects such as rib dimensions and minimum radius of the hub which determines the packaged size of the antenna are found out. Finally a geometrical model for the above design is developed in AUTOCAD.