STIFFNESS DESIGN OF DEPLOYABLE SATELLITE ANTENNAS IN DEPLOYED CONFIGURATION

A new design method is described that ensures the first frequency of d eployable satellite antennas in the deployed configuration. Deployable satellite antennas are modeled as a coupled system; the reflector (an elastic body) is supported by an antenna deployment mechanism (a coil spring). The displacement of the reflector In the system is expressed as the sum of the elastic displacement and the rigid-body displacemen t due to spring rotation. The system vibration equation is obtained by substituting kinetic and potential energies into Lagrange's equation. An eigenvalue problem Is solved for the coupled system to obtain freq uency relationships. A procedure is presented to establish stiffness r equirements of the antenna deployment mechanism so that the deployable antennas caps meet the frequency requirements. To confirm the propose d design method, calculations were made on the deployable antenna for the Japanese experimental Test Satellite VI. The actual frequency of t he deployable antenna was measured in orbit. Measured results indicate the feasibility of the method for designing the stiffness of deployab le antennas.