基于对称性时域近场物理光学法的大口径抛物面电磁散射特性分析

Analysis of the electromagnetic scattering characteristics oflarge-aperture parabolic surface based on symmetrical timedomainnear-field physical optics method

射电望远镜具有极高的灵敏性,干扰信号经由大口径抛物面结构反射后会对观测系统产生较大影响,其电磁兼容分析是一个不容忽视的研究问题.针对大口径抛物面近场耦合分析面临的电大尺寸问题,本文提出了一种基于空间对称性的时域近场物理光学法,解决了大口径抛物面近场电磁散射计算问题.阐述了物理光学近似法建立抛物面近场电磁散射模型的原理,利用局部格林函数近似法简化了计算过程,采用高斯数值积分方法进行面元积分,得到了焦点处近场散射场强.在此基础上,结合抛物面结构和应用场景,提出了基于空间对称性的高效计算方法.最后基于矩形金属板和小口径抛物面模型验证了算法的准确性和高效性,并对25 m大口径抛物面天线近场散射特性进行了计算分析.本文提出的基于对称性时域近场物理光学法为大型射电望远镜近场耦合分析提供了一种技术途径.

Radio telescopes are highly sensitive, and the interference signals reflected by the large aperture paraboloid have asignificant influence on the observing system. Further, electromagnetic compatibility analysis of radio telescopes is aresearch problem that cannot be ignored. To address the issue of electric-large target in the near-field coupling analysis ofthe large-diameter paraboloid, a spatial symmetry-based time-domain near-field physical optics method is proposedherein. The principle of establishing the near-field electromagnetic scattering model of the paraboloid by physical opticsapproximation is described. The local Green’s function approximation method was employed to simplify the calculationprocess, and the surface element integration was performed by the Gaussian numerical integration method. On this basis,combined with paraboloid structure and application scenarios, an efficient spatial symmetry-based calculation method isproposed. Finally, the accuracy and efficiency of the algorithm were evaluated based on a rectangular metal plate and asmall-aperture parabolic, and the near-field scattering characteristics of the large-diameter (25 m) paraboloid antennawere analyzed. The proposed symmetric time-domain near-field physical optics method offers a technical approach forthe near-field coupling analysis of large radio telescopes.