中文摘要：

采用指数型分布粗糙面模拟实际的粗糙地面，运用 FDTD 方法研究了超宽带高斯脉冲电磁波入射粗糙地面时的宽带前向电磁散射问题；通过数值计算得到前向散射系数随频率的变化曲线，并与时谐场源激励下的结果进行了对比；分析了不同的粗糙地面高度起伏相关长度、均方根高度，土壤湿度和入射角下前向散射系数随频率的变化关系，得到了指数型分布粗糙地面的宽带前向电磁散射特性。数值计算结果表明各参数的变化对前向电磁散射系数的影响比较明显，入射波不同极化方式下的前向散射系数也有显著变化。

英文摘要：

The actual rough land surface is simulated with the exponential type distribution rough surface,the wide-band forward electromagnetic scattering from rough land surface under UWB Gaussian pulse electromagnetic wave incidence is studied using FDTD.The curves of forward electromagnetic scattering coefficient varied with frequency are obtained by numerical calculation,and compared with result under harmonic field source.The forward electromagnetic scattering coefficient varying with frequency is analyzed under the difference of the correlation length and the root-mean-square of rough land height fluctuation,the moisture capacity of soil,the incidence angle.The characteristics of the wide-band forward electromagnetic scattering from rough land surface are obtained.The numerical results show that the influence of various parameters on the forward electromagnetic scattering coefficient is obvious.Moreover,forward scattering coefficient with the changes of the incident polarization modes is also significantly different.