Surface accuracy analysis and optimization design of rib-mesh paraboloidal antenna reflectors

Abstract

For deployable paraboloidal antenna reflectors, a rib-mesh structure configuration is suitable owing to its high packing efficiency and reliability. In this configuration, the only supporting members are the ribs. Achieving a sufficient surface accuracy is the primary challenge. In this paper, the rib-mesh antenna reflector structure is divided into two types: a fold-rib structure with a rigid boundary and a wrap-rib structure with an elastic boundary. For each type, a form finding method based on the finite element method (FEM) as well as a rib shape optimization method for enhancing the surface accuracy using a genetic algorithm (GA) are proposed. For the fold-rib structure, the geometric parameters and prestress changes in the mesh shape are analyzed. It is found that the stress ratio influenced the surface accuracy, but the number of ribs is the decisive factor. For the wrap-rib structure, parametric analyses of rib deformation and surface accuracy are conducted. It is found that several parameters significantly affect the deformation, but their influence on the surface accuracy can be almost eliminated by optimization. Following the proposed design method, a prototype of a wrap-rib antenna reflector with a 0.5 m aperture and 16 ribs is designed and fabricated. The accuracy values of the measured surfaces are close to the expected values. It is concluded that the whole design process for rib-mesh structure configuration can be considered to be effective and operable.