The Study Of Wide-band Electromagnetic Scattering From The Land Surface And Wide-band Composite Scattering From The Land Surface With Target

The study of characteristics of wide-band electromagnetic(EM) scattering from the land surface and wide-band composite scattering from the land surface with target has an important significance and practical value in a number of important research areas, such as clutter suppression, jungle perspective, radio fuse, target detection and identification,the remote sensing, pavement detection, wireless communication, as well as surface optics. In this thesis, the theory of wide-band EM scattering from the land surface and wide-band composite scattering from the land surface with target and finite-difference time-domain(FDTD) method are introduced, EM scattering from the land surface and composite scattering from the land surface with target under pulsed wave excitations are investigated systematically. Firstly, the wide-band EM scattering from the land surface with a medium is studied. Secondly, the actual highway pavement system, for example,the characteristics of wide-band backward EM scattering from highway pavement is researched. Finally, the wide-band composite scattering from the land surface with triangle target and multiple rectangular targets are examined separately. The main works and results are listed as follows:1. The two pulse wave sources are given, the four-component model of dielectric constant of soil that J.R. Wang and T.J. Schmugge set up is introduced, and the actual land surface is simulated by Monte Carlo method and fractal function, the wide-band EM scattering from exponential type distribution land surface and fractal land surface under Gaussian pulse wave irradiation is studied using FDTD, the distribution curves of forward and backward scattering coefficient with frequency are obtained, the influence of roughness parameters of land surface, the permittivity of land surface and incident angle on forward and backward scattering coefficient are analyzed.2. Highway pavement structure model are introduced, the natural highway pavement of layered medium is simulated by exponential rough surface, and the EM scattering model from asphalt concrete pavement of FDTD is established. Thecharacteristics of wide-band EM scattering from asphalt concrete pavement systems and disease pavement systems under differential Gaussian pulse wave irradiation are studied using FDTD, and the frequency response curves of backward scattering coefficient are obtained, the influence of roughness parameters of highway pavement, depth and permittivity of surface course, depth and permittivity of base course, the incident angle,and disease parameters on backward scattering coefficient are analyzed.3. The natual land surface is simulated employed by Monte Carlo method, and the EM scattering FDTD models from land surface with two dimensional triangle target above it and multiple rectangular target buried partly are established. The characteristics of wide-band EM scattering from the two models under Gaussian pulse wave irradiation is investigated using FDTD. The curves of backward composite scattering coefficient varied with frequency are obtained, and the dependence of backward composite scattering coefficient on roughness values of land surface, soil moisture, the size of targets, distance between the target and the rough surface, tilt angle of target, and permittivity of target are discussed.