The effects of the backscattering enhancement on signals of rain radar

点击翻译按钮获取中文摘要

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.