引言在卡塞格伦天线中,付反射面、支杆对辐射电磁波都有阻挡。它们在主口径面上形成的阻挡阴影通常用几何光学方法计算。(而阻挡场对天线效率、旁瓣电平的影响就是照射函数对阻挡阴影的“加权”面积)实际上射频阴影比光学阴影宽,所以光学阴影仅是一种近似。如果频率很高,支杆宽度2ηo≥λ,那么几何光学方法就可以得到充分的应用。 Introduction In the Cassegrain antenna, pay the reflective surface, the strut on the radiation electromagnetic waves are blocked. The blocking shadow they form on the primary aperture is usually calculated using the method of geometrical optics. (The influence of the blocking field on the antenna efficiency and the sidelobe level is the “weighted” area of ​​the blocking shadow by the illumination function.) The RF shadow is actually wider than the optical shadow, so the optical shadow is only an approximation. If the frequency is high, the strut width 2ηo ≥ λ, then the method of geometrical optics can be fully applied.