基于遗传算法的余割平方波束天线优化设计

Optimization design of cosecant square beam antenna based on genetic algorithm

[目的]为了使天线性能在要求的角度范围内满足设计指标,提出一种基于物理光学理论分析天线远场性能以及采用遗传算法优化反射器形面的余割平方波束天线方法。[方法]首先,通过优化设计反射器形面来调整相位分布,解决天线方向图变形问题。然后,采用B样条函数来表征反射器的形变量,以天线在俯仰面不同角度的增益为优化目标,利用遗传算法来获得最优的设计结果。最后,采用自编程序对某个余割波束天线进行优化仿真。[结果]仿真结果表明,优化后反射器形面的形变量随天线x轴方向的增大而逐渐增大,但其相对标准抛物面的形变量都在0~0.12 m的范围内,且整个反射器形面的形变较光滑;经过进一步优化后,在0°~70°内天线增益均高于设计指标要求,在30°~60°内天线增益较之前最大提高了约1.2 dB。[结论]采用该优化设计方法不仅提高了天线的可加工性,还降低了系统的复杂度,在工程应用中具有重要的指导意义。

[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 farfield 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.