| This dissertation presents the theoretical studies of electromagnetic (EM) scattering from the rough surface and the composite scattering from the rough surface with the target. Emphasis is put on studying the EM scattering from the single and layered random rough surface, the composite EM scattering from the buried and partially buried target at the rough surface, the hybrid method combining the moment of method (MOM) with the Kirchhoff approximation (KA) and the reciprocity theorem applied to the composite EM scattering from the target above the rough surface, as well as the investigation on the composite transient scattering from the rough surface and the target. The main works are as follows:1. The tapered incident wave is introduced into the classical KA to study the scattering from the 1- and 2-D randomly rough surface with the consideration of the shadowing effect. The numerical results are compared with those obtained by classical KA and MOM, which shows our results is in good agreement with those by MOM, and has a higher accuracy than the classical KA.2. MOM combining with KA considering the tapered incident wave for the analysis of the EM scattering from layered rough surface is investigated The scattered field from the upper rough surface is solved by MOM and the transmitted field from the lower rough surface into the free space is obtained by KA with neglecting the multiple scattering. The influence of the relative parameters on the bistatic scattering coefficient of Gaussian rough surface for different polarizations is discussed in detail.3. The formula for calculating the composite scattering coefficient of the buried and partially buried targets at 1-D dielectric random rough surface with lossy media is derived and solved by MOM with point matching. The effects of the root-mean-square height, the correlative length of the rough surface, the relative permittivity, the depth, as well as the size of the target on the bistatic scattering coefficient are also investigated.4. The hybrid method combining MOM with KA is proposed for the analysis of the bistatic composite EM scattering interaction between the 2-D infinitely long conducting target with arbitrary cross section and the 1-D random rough surface. The EM scattering region is divided into KA and MOM region. The computational time and memory requirements of the hybrid method mainly depend on the number of unknowns of the target. The numerical results are compared and verified with those obtained by MOM, which shows the higher accuracy and efficiency of the hybrid method than that of MOM. Finally, the influence of the surface roughness, the size and the height of the target on the bistatic scattering coefficient for different polarizations is examined.5. The reciprocity theorem used in the scattering between two adjacent targets is extended to solve the coupling field between the time-varying lossy dielectric ocean and a moving conducting plate. The backscattered field from the ocean is evaluated by the KA method. The surface electric and magnetic currents on the ocean, as well as the scattered field from the conducting plate, are evaluated by the Physical Optics method. Meanwhile, the coupling field between the ocean and the plate can be obtained by the reciprocity theorem. Finally, the characteristics and the Doppler spectrum of the composite backscattered field are discussed in detail.6. The Time-Domain-Integral-Equation method is proposed to study transient composite EM scattering from the 1-D perfect electric conducting (PEC) Gaussian rough surface and the 2-D infinitely long conducting target with an arbitrary cross section. Based on the electric field integral equation in time domain, the explicit and implicit solutions of Marching-on-Time (MOT) are presented. The current response at the center of the rough surface and the far electric field response with the time in the composite scattering model are calculated and analyzed. The numerical results are compared and verified with those obtained by conventional MOM-IDFT. Finally, the influence of the incident angle, the size and the location of the target on the current and the far electric field response is analyzed in detail.
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