Design and Verification for Umbrella-Type Deployable Antenna of Chang'e-4 Lunar Relay Satellite

The radial rib deployable antenna is the key equipment for the Chang'e-4 lunar relay satellite,which provides relay communication for the Chang'e-4 lander and inspector landing on the back of the moon. In this paper,the design principle and structure of the radial rib deployable antenna are described,and the technical difficulties such as on-orbit deployment,mesh formation and maintenance,and ultra-low temperature environmental adaptability are analyzed. For the In-orbit deployment of antenna,slow-release spring distributed drive deployment technology is adopted,which has the advantages of flexible layout,lightweight,small installation volume and high reliability. Experiments of life and thermal vacuum environment deployment are carried out to verify the correctness of the antenna deployment technology. Double-layer network structure is adopted to realize the formation and maintenance of antenna mesh,and optimize the number of tension mesh nodes. The test and thermal deformation prediction of the antenna on-orbit verify that the accuracy of the antenna on-orbit profile is up to sub-millimeter,It ensures that the antenna on-orbit performance meets the mission requirements. The verification of the ultra-low temperature environment, with the lowest temperature reaching -250℃,show that the performance of the antenna is unvarying under the extreme low temperature,which meets the adaptability of the antenna on-orbit environment. The verification results effectively support the smooth implementation of the relay communication task of Chang'e-4 lunar relay satellite.