Circular polarization ratio (CPR) was regarded as an important index for detecting water ice in the permanently shaded region (PSR) of the Moon poles. However, many studies have intuitively described that the double‐bounce scatte ring caused by dihedral consisting of rock facets and the lunar rough surface may yield high CPR. Under a large local incidence angle, single scattering is reduced. Double‐bounce scattering of the dihedral governs the echoes and leads to an enhanced CPR. In this paper, a numerical model of the lunar rough surface with discrete scatterers, for example, rock bodies, is developed. The bidirectional analytic ray tracing (BART) method is applied to numerically solve high‐order scattering of this surface/rocks model. The lunar surface is modeled by the Digital Elevation Model (DEM) data from Lunar Reconnaissance Orbiter (LRO) Lunar Orbiter Laser Altimeter (LOLA). This paper quantitatively analyzes how the surface topography, rocks, radar local incidence, etc, affect the CPR. It is found that at a small local incident angle, the single scattering is usually dominant and results in a small CPR. When the local incident angle becomes large, the radar wave reflected in the specular direction is more likely to be reflected again and increases the CPR.

中文翻译：

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离散RF散射的粗糙表面CPR数值模型

圆极化率（CPR）被认为是检测月极永久阴影区（PSR）中水冰的重要指标。但是，许多研究直观地描述了由岩石面和月球粗糙表面组成的二面体所造成的双反弹散射环可能会产生较高的CPR。在较大的局部入射角下，减少了单次散射。二面体的双反弹散射控制回波并导致增强的CPR。本文建立了具有离散散射体（例如岩石体）的月球粗糙表面的数值模型。双向分析射线追踪（BART）方法用于数值求解该表面/岩石模型的高阶散射。月球表面由来自月球侦察轨道器（LRO）的月球轨道激光高度计（LOLA）的数字高程模型（DEM）数据建模。本文定量分析了表面地形，岩石，雷达局部入射等如何影响心肺复苏。发现在小的局部入射角处，单个散射通常是主要的并且导致小的CPR。当局部入射角变大时，在镜面方向上反射的雷达波更有可能再次被反射并增加CPR。