The effects of the backscattering enhancement on signals of rain radar

研究了毫米波雷达测雨信号的后向散射增强。这种效果很难在向后方向的非常小的角度内以高分辨率观察到。然后在30GHz下对大型球形散射体的极化雷达参数进行了实验室测量，以研究入射极化状态的依赖性。测量的线和圆退偏比与理论计算吻合良好，表明由于多次散射的圆偏振的交叉极化水平是非常大的相比，线偏振。利用50GHz散射计对脉冲后向散射波进行了分析，以区分多次散射过程和接收脉冲波形。结果表明，散射过程被证实是分离的时间分辨率为3纳秒。在利用机载雷达测量降雨率时，雷达信号中包含了来自海面的回波。为了评估这一点，在实验室实验中检查了平坦和粗糙边界附近散射体的散射。边界粗糙度对接收脉冲波形有影响，尤其是在散射体与粗糙边界之间的二阶散射中。

The backscattering enhancement in rain radar signals at millimeter waves was examined. This effect was difficult to observe with high resolution within a very small angle in the backward direction. Laboratory measurements of polarimetric radar parameters for large spherical scatterers were then performed at 30GHz to study the dependence on incidence polarization states. The measured linear and circular depolarization ratios were in good agreement with theoretical calculations, showing the cross-polar level of circular polarization due to multiple scattering is very large compared with that of linear polarization. The backscattered pulse wave using the 50GHz scatterometer was also analyzed to distinguish the multiple scattering process from the received pulse shape. The results indicated that the scattering process was confirmed to be separated with the time resolution of 3 nsec. In measuring the rain rate by the air-born radar, the echo from sea surfaces was included in radar signals. To evaluate this, the scattering.from scatterers near flat and rough boundaries was examined in laboratory experiments. The surface roughness of the boundaries was found to affect the received pulse shape, especially in the second order scattering between scatterers and rough boundary.