| Reflector antenna is widely used in satellite communications due to its advantages of wide beam coverage,high gain,and simple structure.Beamshaping based on reflector antenna is studied in this thesis.Two methods are applied to realize the beamshaping of reflector antenna,including optimization of the reflector antenna surface and the optimization of the reflector antenna feed array..The control technique of reflector based on Zernike polynomial is introduced.The influence of Zernike polynomial expansion coefficients on the shape and radiation pattern of the reflector antenna is discussed.The hummingbird optimization algorithm is applied to optimize the shape of reflector antenna to improve beam performance.Two single-offset parabolic antennas are designed.The approximate circular symmetry shaping method is adopted to ensure that the beams of reflector antenna are approximately circularly symmetric and do not generate dents,and at the same time,the deformation of the reflector is small.The strategy of preferentially optimizing the gain and then optimizing the interference ration is adopted.Finally the beams with good performance are realized.The beamshaping of the reflector antenna based on feed array optimization is discussed.The uniform linear array,square array and hexagonal array are introduced.The influence of the element spacing and the number of elements on the radiation pattern of reflector antenna is analyzed.The beam performance of the reflector antenna is improved by optimizing the feed excitation coefficients to achieve beamshaping.Three single-beam array-fed parabolic antennas were designed to realize beamshaping in circular,square and irregular regions.Two multibeam array-fed parabolic antennas were designed to achieve high-gain multibeam to cover designated areas. |
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