Yiqun Zhang

Planar Array Synthesis for Optimal Microwave Power Transmission With Multiple Constraints

This letter describes a synthesis method of uniformly excited, unequally spaced planar array with maximum beam collection efficiency based on the chaotic particle swarm optimization algorithm. Here, the multiple optimization constrains include the number of array elements, the aperture, the minimum element spacing, and the maximum sidelobe level outside the receiving region. Through this method, feeding network of the array becomes simple and compact. Effectiveness of the proposed method is validated by comparing the simulation results obtained in this letter to those reported in the state-of-the-art literature.

Study of Stepped Amplitude Distribution Taper for Microwave Power Transmission for SSPS

A novel stepped amplitude distribution (SAD) taper for microwave power transmission for space solar power satellite is proposed in this paper. The SAD taper is described by the summation of the Heaviside step functions. Through optimizing the “height” and “radius” of each step of the descriptive function, the maximal beam collection efficiency (BCE) with and without constraints on the radiation levels can be obtained. A large set of numerical experiments on continuous apertures and discrete antenna arrays are carried out. The results show that the obtained BCEs can be close to or even higher than those of the 10-dB Gaussian ones, which shows the superiority of the method. In addition, only several kinds of amplifiers are required in this method, and therefore, the cost and complexity of the system can be greatly reduced.

Uniform-tension form-finding design for asymmetric cable-mesh deployable reflector antennas

Space antennas with high gain and high directivity are in great demand for future communication and observation applications. Deployable cable-mesh reflector antennas are required to be tensioned in a self-equilibrated state through form-finding design. In order to ensure the cable-mesh reflector antennas’ high performances, both surface accuracy requirements and tension uniformity should be considered in the form-finding design process. To effectively implement the form-finding design for asymmetric cable-mesh antennas, a two-step uniform-tension form-finding approach is presented. In step 1, with the cable tension and membrane stress being considered simultaneously, an iterative design technique which combines force density method and surface stress density method is presented. In step 2, considering the asymmetry between the rear and front nets, the nodal z-coordinates and cable tensions of the rear net are designed with the combination of the equilibrium matrix method and force density method. Finally, an offset AstroMesh antenna is designed using the proposed method. For the obtained antenna, the cable tension and membrane stress of the front net are completely uniform, and the maximum tension ratio of the rear cable net is 1.06, which are very satisfactory.

Shape pre-adjustment of deployable mesh antennas considering space thermal loads

On-orbit space deployable antennas withstand periodic thermal loads, which will degrade the antenna surface accuracy. Thus, it is necessary to preliminarily adjust the antenna before launch to make it adapt to the space temperature environment as much as possible. Aiming at this problem, a pre-adjustment method based on min-max concept is presented in this study. First, according to the force equilibrium equation of the cable element, the incremental equilibrium equation of the cable mesh antenna is derived, and the incremental expressions of the reflectors surface displacement and cable tension with respect to cable length variation and element temperature variation are also developed. Then, the optimization model for shape pre-adjustment is established using min-max method, and the pre-adjustment process is implemented by sequence planning strategy. Finally, an AstroMesh antenna is employed to demonstrate the validity of the method.

A Novel Contoured Beam Synthesis Method for AstroMesh Reflectors Based on Integrated Electromagnetic-Structural Design

The self-equilibrium characteristic of the tensioned AstroMesh reflector antennas leads to the result that the concave–convex reflector surface for contoured beams cannot be realized by AstroMesh reflector antennas. To realize the contoured beam synthesis for AstroMesh reflector antennas, a novel contoured beam synthesis technology based on integrated electromagnetic-structural design is presented, and the corresponding optimization model is established. In the model, with all the force densities being constrained to be positive, force densities of the AstroMesh reflector antennas are designed to realize the desired far-field pattern. Moreover, the tension uniformity of the AstroMesh reflector antenna is additionally chosen as an objective function to ensure that the shaped AstroMesh reflectors have excellent engineering practicability with good tension uniformity. Finally, a shaped AstroMesh reflector antenna is designed to produce a contoured beam covering the continental United States (CONUS), which verified the effectiveness of the proposed method.