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为了使星载天线的远场方向图与服务区的形状相匹配,并在服务区内获得高的增益和交叉极化隔离度,通过雅可比-贝塞尔(Jacobi-Bessel)函数来表示反射面的形状,应用极小极大值(Minimax)算法对单偏置抛物反射面天线进行优化设计。在优化过程中,把表征反射面形状的展开系数作为优化参数,利用物理光学(PO)与物理绕射理论(PTD)相结合的方法来计算远场,同时考虑了天线的增益和交叉极化隔离度,并对反射面的形变量加以限制来保证最终优化得到的星载反射面天线能够应用现有技术和材料加工出来。最后以产生一个覆盖巴西全部领土的赋形波束为例进行了优化设计,数值仿真结果表明:在服务区内主极化增益都高于28.5 dBi,交叉极化隔离度都在21 dB以上。
In order to match the far-field pattern of the spaceborne antenna with the shape of the service area and obtain high gain and cross-polarization isolation within the service area, the reflection is represented by the Jacobi-Bessel function Surface shape, the Minimax algorithm is used to optimize the design of the single bias parabolic reflector antenna. In the optimization process, the expansion coefficient that characterizes the shape of the reflector is taken as the optimization parameter, and the far field is calculated by the method of physical optics (PO) and physical diffraction theory (PTD). The gain and cross polarization Isolation, and to limit the amount of deformation of the reflecting surface to ensure that the finally optimized spaceborne reflector antenna can be fabricated using current technology and materials. Finally, a beamforming beam covering the entire territory of Brazil is used as an example to optimize the design. The numerical simulation results show that the main polarization gains are both above 28.5 dBi and the cross-polarization isolation is above 21 dB in the service area.