Objectives  In order to make the antenna performance meet the design requirements in required angle range, an optimized design method of cosecant square beam antenna is proposed, which analyzes the far-field performance of the antenna based on the physical optics theory and optimizes the reflector shape through the genetic algorithm.

  Methods  The phase distribution was adjusted by optimizing the shape of reflector, thus the problem of antenna pattern distortion can be resolved. The B-spline function was used to characterize the distortions of the surface and the gain of antenna at different angles on the elevation plane was set as optimization objective of genetic algorithms. Finally, a cosecant beam antenna was optimized and simulated by a self-designed program.

  Results  The simulation results show that the shape variable of the optimized reflector gradually increases with the increase of the x-axis direction of the antenna, but the shape variable of the optimized reflector is in the range of 0~0.12 m when compared with the standard paraboloid, and the deformation of the whole reflector is relatively smooth; after further optimization, the gain of the antenna is higher than the design index in the range of 0°~70°, and the gain of the antenna is about 1.2 dB higher than the previous design index in the range of 30°~60°.

  Conclusions  This design method is of great guiding significance, which can not only improve the machinability of the antenna, but also reduce the complexity of the system in engineering application.