Abstract: Research on UWB（Ultra-Wideband） ground echo provides simulation supports for designs of UWB devices.For the sake of reliability of calculation，the dispersion of soil and fluctuation of ground surface should be taken into account.FDTD（Finite Difference of Time Domain） algorithms applied in ground echo calculation at present have the disadvantages of slow speed or large errors.By using CPML（Convolutional Perfectly Matched Layer） as absorbtion boundary condition，and multi-pole Debye model as soil complex dielectric coefficients，a CPML-FDTD algorithm is derived in multi-pole Debye media.Simulation is carried out under different conditions，and comparison with non-PML FDTD algorithm proves the validity and efficiency of the proposed algorithm.

Key words: Finite Difference of Time Domain（FDTD）, Convolutional Perfectly Matched Layer（CPML）, Ultra-Wideband（UWB） signal, ground echo, multi-pole Debye model

摘要： 研究地面的超宽带回波特性，能够为超宽带无线电系统设计提供仿真支持。为保证计算结果的可信性，需要考虑土壤的色散特性和地面起伏对回波的影响。目前在超宽带地面回波计算中所使用的FDTD（时域有限差分）算法计算量较大或者存在较大误差。使用卷积完全匹配层（CPML）作为吸收边界，多极点Debye模型描述土壤介质特性，在FDTD算法基础上推导出了多极点Debye介质的CPML-FDTD算法。对不同条件地面的回波进行了仿真计算，与未使用PML（完全匹配层）的FDTD算法计算结果进行比较分析，表明文中使用的算法结果正确且效率较高。

关键词: 时域有限差分, 卷积完全匹配层, 超宽带信号, 地面回波, 多极点Debye模型