中文摘要：

该文提出一种新的双尺度（Modified Two-Scale Model,MTSM）粗糙度地表微波散射模型,采用小波包变换的方法将面上的粗糙度（z（x,y））变换到频域进行处理,粗糙度频谱的低频部分代表大尺度分量,高频部分代表小尺度分量,然后分别用基尔霍夫近似和小扰动模型来分别模拟大小尺度的粗糙度,考虑到小尺度的粗糙度是叠于大尺度粗糙度之上,模型在计算小尺度粗糙度的后向散射贡献时还考虑了大尺度起伏造成的几何倾斜。MTSM的解为大尺度粗糙度的基尔霍夫解加上几何倾斜修正后的小尺度粗糙度的小扰动解。最后采用改进的积分方程模型（AIEM）对MTSM做了初步的验证,结果表明在入射角θi〈30°,粗糙度较小（ks=0.354）的时候,MTSM有比较好的精度。

英文摘要：

In this paper, we present a Modified Two-Scale Microwave（MTSM） scattering model to describe the scattering coefficient of naturally rough surfaces. The surface roughness is assumed to be Gaussian in the proposed model so that the surface height z（x, y） can be split into large- and small-scale components by the wavelet packet transform according to electromagnetic wavelength. We used the Kirchhoff Model（KM） and Small Perturbation Method（SPM） to estimate the backscattering coefficient of large- and small-scale roughness, respectively. The tilting effect caused by the slope of large-scale roughness was corrected when calculating the contribution of backscattering to small-scale roughness. The backscattering coefficient of the MTSM comprised the total backscattering contributions of surfaces with both scales of roughness. The MTSM was tested and validated using the Advanced Integral Equation Model（AIEM） for dielectric randomly rough surfaces. The accuracy of the MTSM showed favorable agreement with AIEM, both when the incident angle was less than 30°（θi〈30°） and when the surface roughness was small（ks=0.354）.