侧馈偏置卡塞格伦天线的面赋形研究

Study of the shaping reflector for side-fed offset cassegrain antennas

为改善星载天线的宽角扫描特性,采用射线追踪的方法,通过优化的思想对侧馈偏置卡塞格伦(SFOC)天线的主反射面进行了面赋形设计.为增加反射面表达式的灵活性,设计时首先根据反射面的初始数据,以双三次B样条函数逼近其形状,然后以各馈源相位中心到与其对应的扫描口径面的路径等长为优化目标,通过Powell方法对样条函数的插值数据点进行调节,最终确定了反射面的形状.分析结果表明,面赋形工作有效降低了SFOC天线一维扫描和二维扫描过程中由相位误差带来的增益损失,改善了该天线系统的宽角扫描特性.

To improve the wide-angle scanning properties of the satellite antenna, we concentrate on the shaping of the main reflector of the Side-Fed Offset Cassegrain （SFOC） antenna by the method of the ray tracing and the idea of the optimization. In the process of reflector shaping, in order to enhance the flexibility of the expression for the reflector, a two-dlmensional cubic B-spline is used to approach the reflector surface according to the initial data, Then, taking the rays＇ paths wh/ch are equal from every feed to corresponding apertures as the optimization objective, the interprolation data points for the spline function are adjusted with Powell＇s direct method, and in this way, the shaped reflector surface is obtained. The analytical results indicate that the 1-D and 2-D gain degradations of the SFOC antenna due to the aberration are reduced remarkably, and thus the wide-angle scanning properties of the SFOC is improved.