| In recent years, the electronic scanning microstrip antennas have been developed rapidly. Comparing with the conventional microstirp antenna, the antenna beam of the electronic scanning microstrip antenna can scan at some area. It provides a lot of advantages on the radar systems. Based on the requirements of engineering, some researches on the microstrip leaky-wave antenna and digital beam forming antenna have been proposed in this thesis. The main contents and contributions of the thesis are listed below:1. Design a DBF microstrip antenna array. Firstly, the arrangement of the whole antenna array has been investigated to accommodate the requirements of the engineering specifications. Through comparing the performances of several array arrangements, the sub-array consisted of 4X4 elements has been applied in the design. The matching stub has been considered in the design of sub-array to improve the yield of antenna. Furthermore, a calibrating port has also been designed in each sub-array. Through this calibrating port, the energy coupled from the antenna array can be given to the calibrating network. Finally, the arrays have manufactured and measured. From the measured results, it shows that the bandwidth of the antenna is 500M and the maximum gain is 17dBi. The pass-rate is 100%. In addition, a novel air cavity backed patch 2x2 sub-arrays have been investigated. Comparing with the convention 4X4 subarray, this array can achieve the flat gain curve in the bandwidth.2. Design a microstrip leaky-wave beam-scanning antenna. It can achieve the high efficient and frequency scanning performances. The feed structure, antenna size and dielectric thickness have been optimized to achieve the best performances. Then, a microstrip leaky-wave antenna array have been designed and measured. From the measured results, the maximum gain of the antenna is 20.4dBi and its beam scanned 40deg with 2GHz bandwidth. |
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