Abstract Surface distortion reduces the astronomical observation efficiency of large radio telescopes. Based on even-odd phase expansion, we present a semi-analytical phase retrieval algorithm for antennas equipped with an active surface system to detect its surface distortion. In the method, the odd-part distortion is solved directly from the focused far-field pattern, and the even-part is solved by adding a defocused scanning. We propose a window-shape defocusing scheme that is superior to the conventional defocusing scheme of moving sub-reflector. When the antenna is slightly distorted (aperture phase aberration

中文翻译：

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基于奇偶相位展开的大型有源反射面天线表面检测方法

摘要 表面畸变降低了大型射电望远镜的天文观测效率。基于奇偶相位展开，我们提出了一种半解析相位检索算法，用于配备有源表面系统的天线来检测其表面畸变。该方法通过聚焦远场图直接求解奇数部分畸变，加上散焦扫描来求解偶数部分畸变。我们提出了一种优于传统移动副反射器散焦方案的窗形散焦方案。当天线轻微失真时（孔径相位畸变