Papers by Keyword: Deployable Antenna

Abstract: There is a wide application for the string-net structure in the areas of architecture and spaceflight. In the area of spaceflight, the string-net structure is mainly used in the deployable antenna. The three-dimensional string-net structure is a kind of typical string-net structures applied on the deployable antenna. Here the string-net structure is analyzed. At first, composition of the string-net structure is presented. Then the dynamical relaxation method is used to obtain the solution for movement of the structure after its instability. At last, using numerical simulation, tensions in the strings are computed. It is proved finally that the three-dimensional string-net structure still possesses the capability of keeping its shape and stiffness after its instability.

Abstract: In order to get the deployable antenna with light weight but large size and high stiffness, this study investigated SMPC self-deployable driver mechanism based on the deformation mechanism of SMPC, and designed the SMPC space deployable antenna. The laminated shell structure with two pieces of back-to-back configuration was analyzed. Finite element analysis revealed that the reasonable central angle of the laminated shell cross-section was 90°. The ends fixing structure of the SMPC hinge was given. The function and structure of the hoop truss deployable antenna were designed to meet the functional and accuracy requirements.

Abstract: The reflector of the astromesh deployable antenna is formed with metallic net fixed on the nodes of its astromesh. The astromesh determines shape of the reflector, so analysis of the astromesh is necessary. With force density method and paraboloid equation, balance equations of the astromesh were set up at first. Length and tension of the cords, coordinates of the nodes and outer forces on the nodes were included in the equations. After the coefficient matrix was transformed, a group of orthogonal normalization basis in its null space was obtained. Solving method of the balance equations was analyzed. After optimized with the genetic algorithm, initial tensions of all cords were obtained finally. The analysis method can make design of the astromesh more rational and reliable.

Abstract: This paper presents a method to measure the deformation of large deployable mesh microwave antenna by using the photogrammetric technology. Because the mesh reflector surface is controlled by 79 nodes, measuring 3D coordinates of these nodes accurately is the key to test the deformation of antenna. The technique of camera calibration, the matching method of the image points, and the solution of measuring 3D points are introduced in this paper. The experimental data is also provided. This paper proposes a method to calculate the spatial coordinates of microwave antenna nodes by using the bundle adjustment with distance constraints. This method is capable of correcting the influences of the lens distortion and improving system measurement accuracy. In reference to the fact that the surface of this antenna is controlled by 79 nodes, and the design parameter of these nodes is already known, a method based on digital surface model constrain is used to solve the image points matching problem. This method efficiently simplifies the computation procedure and shortens the measurement time.

Abstract: This paper is concerned about a design of a new deployable antenna actuated by 6 shape memory alloy (SMA) hinges. The antenna consists of 6 radial, tensioned, parabolic, deployable ribs connecting to a central hub. The hinge, located at each rib, is used of the Nitinol SMA material due to the ability to generate large strains and electrical resistive actuation. The elongated SMA wire is heated by an electrical current, caused to contract in response to a converse thermally-induced phase transformation. The resulting tension creates a moment, imparting rotary motion between two adjacent beams. The concept and operation of deployable antenna system are discussed in detail, and a dynamic simulation is presented. A series of experiments are performed on the SMA actuator to investigate the system behavior in the process of deployment. Results indicated that the hinge with low speed rotation and easy fabrication achieves reliable actuation for the deployment of the antenna, and the antenna demonstrates a high deployment-to-stowage volume ratio.