关键词: 时域有限差分方法/
宽带复合电磁散射/
大地土壤表面/
多目标
English Abstract
Wide-band composite electromagnetic scattering from the earth soil surface and multiple targets shallowly buried
Ren Xin-Cheng1,Zhu Xiao-Min1,
Liu Peng2
1.School of Physics and Electronic Information, Yanan University, Yan'an 716000, China;
2.Key Laboratory for Information Science of Electromagnetic Waves(MoE), Fudan University, Shanghai 200433, China
Fund Project:Project supported by the National Natural Science Foundation of China (Grant No. 61379026), the Science and Technology Research and Development Program Project in Shaanxi Province (Industrial Research), China (Grant No. 2014K05-61), the Foundation of Construction of High-level University Project in Shaanxi Province, China (Grant No. 2015SXTS02), and the Open Foundation of Fudan University Key Laboratory for Information Science of Electromagnetic Waves (MoE), China (Grant No. EMW201502).Received Date:15 March 2016
Accepted Date:22 July 2016
Published Online:05 October 2016
Abstract:Wide-band electromagnetic scattering from multiple objects shallowly buried beneath rough earth soil surfaces has been an important research topic in recent years because of its extensive applications in detecting the buried objects such as mines, pipes, and tunnels. Due to the advantages of finite-difference time-domain (FDTD) method in simulating wide-band electromagnetic scattering from rough surface in the presence of multiple objects, the FDTD method under Gaussian differential pulse wave incidence is utilized in the present study to analyze the frequency response of rough soil surfaces with shallowly buried objects, which serves as a basis for the detection and discrimination of objects buried below rough soil surfaces. The Topp equation model that can predict the dielectric constant of soil-water mixture is adopted in the present study to properly describe the dielectric property of earth soil with water. The actual rough land surface is modeled as the realization of a Gaussian random process with exponential spectrum by using Monte Carlo method. Simulation results show that the variation of composite scattering coefficient with frequency is oscillatory. It is also shown that the composite scattering coefficient versus frequency increases with the increase of root-mean-square of soil surface, water ratio of soil, the target section height, and the separation distance of target. However, simulation results indicate that the composite scattering coefficient versus frequency decreases with the increase of target section width. In summary, the variation of wide-band scattering coefficient is very complicated and is very sensitive to the incidence angle of electromagnetic wave. However, the wide-band scattering coefficient under Gaussian differential pulse wave incidence is less sensitive to the correlation length of rough soil surface, the depth of buried objects, and the dielectric constant of target. These qualitative results relating to the frequency response of rough soil surfaces in the presence of multiple objects are potentially valuable for detecting and discriminating the objects buried below rough soil surfaces by utilizing a wide-band ground penetrating radar system, although the present study is limited to one-dimensional rough soil surface due to the severe computational burden encountered in the large-scale Monte Carlo simulations. In addition, compared with frequency-domain numerical methods, the FDTD method has significant advantages in calculating wide-band composite scattering from rough surfaces in the presence of multiple objects, and thus has extensive applications in radar imaging simulation of multiple objects below or above rough surfaces, which goes beyond the scope of this paper.
Keywords: finite-difference time-domain/
wide-band composite electromagnetic scattering/
the earth soil surface/
multiple targets
