Design Of Regional Coverage Multiple Beam Satellite Antennas And Multiband Terminal Printed Antennas

Communication satellites represent one of the most significant applications of space technology. Today, the applications of communication satellites reach approximately 200 countries, territories, and ocean areas for communication services of all types to both large and small terminals on land, on ships, and on aircraft. Recently,the multi-beam antenna technology was considered for communication satellites to improve the directivity. It can increase the antenna gain substantially in the designated area by using spot beam instead of global beam along with the effective isotropic radiated power and G/T, thus can support the small satellite terminals. And frequencies can be reused between different spot beams, which improve the frequency utilization and the system capacity. Meanwhile, the architectural design of satellite communications payloads has benefited from the adoption of Multiport Power Amplifiers(MPA). In terms of the terminal antenna, multiband printed antenna are now arousing more and more interest in transportable satellite communication terminal devices and wireless mobile terminal devices, because of its attractive characteristics including small size, low profile and low cost, etc. Based on the practical requirements of commercial and military communication system technologies, the fast analysis and synthesis of regional coverage for multiple beam satellite antenna and the novel design of multiband printed antennas have been studied intensively in this dissertation. The author’s major work and conclusions are as follows:1. Regional coverage for multiple beam satellite antenna is investigated. In order to meet the demand of covering given area seamlessly, a type of honeycombs structure of beam distribution is designed according to the locations of service area and the zone of coverage. During the optimum design, a hybrid differential evolution is applied to solve two types of the optimization model in order to reduce the difficulty in system-level optimization. The pattern of the spot beam and C/I are provided and the coverage performances of the design are verified. The optimized 62-beam coverage pattern can cover given area seamlessly, and satisfies the requirement of edge of coverage level and C/I.2. To solve the combinatorial optimization problems, particularly permutation-based integer combinatorial problems, a combinatorial differential evolution algorithm is developed. The proposed method combines the differential evolution algorithm with the differential list of movements and the dual points swap to optimize the discrete optimization problems. Synthesis examples are compared to thesmall-scale combinatorial optimization problem. Numerical result demonstrates that the algorithm is superior in terms of the high quality solutions, relatively small computational cost and fast convergence speed.3. The connection relationship between the feeds and Multiport Power Amplifiers is researched. Firstly, the principle of Multiport Power Amplifiers in the multi-feed,multi-beam antenna system is expounded. Secondly, the important of the design in connection relationship between the feeds and Multiport Power Amplifiers is illustrated.Then the combinatorial differential evolution algorithm is employed for the connection relationship design between the feeds and multiport power amplifiers. Numerical result demonstrates that connection relationship can be optimized efficiently to satisfy the requirements of engineering.4. Multiband antennas are investagated. In order to realize multiband operation and miniaturization, three methods are proposed for antenna designs, including the following:(1) Branch folded. By folding the multiple straight radiation elements, the size can be reduced on the basis of the original antenna.(2) A U-shape compact RF choke. Based on the slot structure, a novel U-shape loaded slots pair has been successfully applied in a multiband log-periodic antenna designs.(3) Asymmetric method. Asymmetric method used in the CPW-fed antenna is able to reduce the antenna size. Measured results show reasonable agreements with simulated results, which confirm the manifesting high reliability and validity of the aforementioned approaches.