二维粗糙海面散射回波多普勒谱频移及展宽特征

基于二维线性海面模型及粗糙面电磁散射的一阶小斜率近似公式，研究了海面回波各阶多普勒谱的频移特性，得到了多普勒谱频移所对应的理论公式，与经典多普勒频移公式相比考虑到了风速、大尺度波浪轨道运动等因素对多普勒谱频移的影响；同时根据粗糙面的双尺度模型，基于多普勒谱频移的物理机理，给出了求解散射场多普勒谱展宽的理论公式.最后将理论公式计算所得结果与模拟结果及实测数据进行了比较，讨论了风速、入射波频率及入射角等因素对多普勒频移及多普勒谱展宽的影响.通过比较可以发现，给出的理论公式可以对多普勒谱频移和展宽进行一定程度的预测. 关键词： 粗糙海面 电磁散射 多普勒谱

Study on the Doppler shift and the spectrum widening of the scattered echoes from the 2-D rough sea surface

Based on the 2-D ocean-like surface of linear model and the first-order small slope approximation，the characteristic of Doppler shift for different order Doppler spectra of scattered echoes is investigated and the formula of Doppler shift is derived. Comparing with the conventional formula of Doppler shift，the influence of the wind speed and the orbit motion of the sea wave in large scale is considered in our result. By employing the two-scale model of rough surface and physical mechanism of Doppler shift，a formula of the spectrum widening for the scattered field from the oceanic surface is also presented. The numerical results evaluated by the formulae in this study are compared with the simulated and the measured data，the dependence of the Doppler shift and the spectrum widening on the parameters，such as the wind speed，the frequency of the incident wave and the incident angle, etc. are discussed. It is found that the formulae obtained in this research can be used to predict the Doppler shift and the spectrum widening.