Research On The Techniques Of Large Antennas For Deep-space TT & C And Communication

Deep-space exploration is one of the three space activities in the new century. Deep-space telemetry, tracking & command (TT&C) and communication system is to complete the TT&C and communication for Deep-space spacecraft. Related tightly to the pre-research project entitled"S/Ka TT&C and Communication System Research", this dissertation presents a systematic investigation into the technique of large antennas for deep-space TT&C and communication, which started with capturing spacecraft using narrow beam-width large antenna under a rough orbit forecast in little time. The major contributions of the dissertation on this subject can be summarized as follows:①The software package for calculating the radiation field of large reflector antenna using Matlab is developed, which based on physical optics. After a brief review of several computational electromagnetic methods and the corresponding commercial software commonly used in antenna design, the method of antenna analysis in this dissertation is addressed. The software package based on physical optics for calculating the radiation field of large reflector antenna is developed with Matlab. The accuracy comparison is carried out between our package and commercial software-General Reflector Antenna Software Package (GRASP). These simulation results show the accuracy of our software package is consistent with commercial software. This package provides the basis for follow-up research.②The performance of reflector antenna system using a focal-plane array, such as sensitivity, efficiency and noise, was analyzed. The antenna performance in terms of efficiency, sentivity and field of view, using a focal-plane array in place of a standard single-mode feed, can be greatly improved. Numerical simulations were performed to compare the large reflector antenna performance between the utilization of an electrically small horn array and an electrically large horn array when beam steering. These simulation results show that the reflector antenna using focal-plane array of electrical-small horn has wider field of view and higher aperture efficiency, comparing with electrically large horn array.③A novel multi-beam spiral scanning method of antennas in deep-space TT&C and communication is proposed. Physical optics was used to compute the far pattern of the antenna for excitation of the individual array elements in focal-plane array. Multiple closely overlapping beams were synthesized with indirect conjugate field matching technique. The simulation results show that, combined with spiral scanning method, the multi-beam reflector antenna can accomplish the desired area scanning in less time under raw obit forecast and the array gain in multi-beam reflector antenna can extend the range of deep-space exploration.④Particle swarm optimization (PSO) is used to synthesis the pattern of the parabolic reflector antenna using a focal-plane array in deep-space exploration. Physical optics was used to compute the far pattern of the reflector antenna for excitation of the individual array elements in focal-plane array, and then stored. Various scanning patterns were synthesized for deep-space TT&C and communication with PSO. These simulated results show that the patterns synthesized with PSO have wider scanning ability, more accurate direction, and lower side lobe, comparing with conjugate field match method.⑤After a detail review of large antennas and array technique in deep-space TT&C and communication, a new computationally efficient algorithm based propagator method for two-dimensional (2-D) direction-of-arrival (DOA) estimation is proposed, which uses two parallel uniform linear arrays. The algorithm takes advantage of the special structure of the array which enables 2-D DOA estimation without pair matching. Simulation results show that the proposed algorithm achieves very accurate estimation at lower computational cost. It's desired in real time and huge planar array DOA application.⑥The array feed technology for large reflector antenna is investigated. A hexagonal feed array of microstrip antenna with EBG is proposed. A horn with choke was designed. Simulated and experimental results show that the choke structure can improve the horn with a flatter main lobe, a steeper edge and a symmetrical pattern. Taking it combining array, mutual coupling can be smaller. After an in-depth study of EBG structure to suppress mutual coupling between antennas, a hexagonal feed array of microstrip antenna with EBG for reflector antenna was designed. A seven elements array was tested. The results show that the EBG structure can suppress the antenna array mutual coupling between elements, as well as improving the matching and circular polarization performance of antenna. The hexagonal array with EBG is competent for the focal-plane of reflector antenna.