Microstrip Array Antenna Research Based On Airborne Synthetic Aperture Radar

Airborne Synthetic Aperture Radar is a imaging radar with advantages of all-weather and all-day working, high resolution, and large coverage, which make this type of radar widely used. Antenna is one of the core subsystems of SAR, and determines the performance of several key parameters of SAR. Therefore, the design of the antenna has a high place in the research and development of the SAR system.Under such background, the antenna of SAR is researched. Microstrip antenna array, which is a hotspot in the research of the antenna of SAR-air, is used to implement a SAR antenna system with high performance of wide bandwidth, high gain, low side lobe, and great directivity.3 types of wide-bandwidth microstrip antennas with different structures, which are aperture-coupled stacked microstrip antenna, U-slot stacked microstrip antenna and half U-slot stacked microstrip antenna, are designed on center frequency. The relative bandwidth of the three types of microstrip antennas are all more than 15%, which can meet the requirement of wide bandwidth. Among them, the area of plane of half U-slot stacked microstrip antenna is nearly 50% smaller than that of U-slot stacked microstrip antenna, which is a new attempt of miniaturized antenna. Through the overall evaluation of the characteristics of bandwidth, directional diagram, and cross polarization, it is determined to use U-slot stacked microstrip antenna array in the design of antenna of SAR-air.Pattern synthesis is the major work of antenna array design. Evolutional algorithm is a novel and effective method to optimize the array weight of the array elements. The array weight of a 8×8 array is optimized ignoring the cross coupling, through a novel cultural algorithm platform. The pattern acquired has low side lobes and narrow half-power lobe width, which can meet the requirements. And the feasibility of the proposal is tested and verified theoretically.In order to examine the correctness of the theoretical derivation and the simulated optimization, an experimental 2×2 unit U-slot stacked microstrip antenna is processed. Both the near field and the far field characteristics acquired by actual measurement are contiguous to the results of the theoretical derivation and the simulated optimization.With the main line of the design of the SAR antenna, the developing flow, from the target index setting to the model selecting, evaluation, designing, testing, and the analyzing of the antenna, is introduced. A project both from the design of each unit to the pattern synthesis of the array, and from the software simulation to the actual testing is completed. The achievement can be used as a source of reference to both theoretical innovation and engineering practice.