Research On Integral Equation Method And Its Key Techniques For EM Scattering By Three-Dimensional Objects In Multilayered Media

Numerical analysis methods for electromagnetic radiation and scattering by objects in planar multilayered media have urgent need in many applications such as integrated modeling of radar targets and environments, geophysics exploration, remote sensing, microstip antenna and circuit simulation and signal integrality analysis and so on. This dissertation studies the integral equation method and its key techniques for three-dimensional scattering problems in multilayered media.In the first, the multilayered media mixed potential integral equation (MM-MPIE) method is discussed in a general sense. The proper integral equation and corresponding Green's functions (GFs) are formulated for objects arbitrarily located in multilayered media background and for overcoming the complexity resulted from the case of object penetrating the interfaces. Due to the importance of Green's functions for multilayered media problems, the dissertation has independently derived out the spectral representations of the GFs, by which the efficient algorithms for free space problems can be easily extended to multilayered media case. The derivations lay a good foundation for the efficient evaluation of GFs and the fast solving of scattering problems by the method of moments (MoM).As key techniques for solving the multilayered media problems by integral equation method, the methods to evaluate the Sommerfeld integrals for GFs are investigated in details, including the direct integration method, the fast integration method along the steepest decent path (SDP), the discrete complex images method (DCIM) and so on. These techniques guarantee the realization and fast solving of the electromagnetic scattering by complex objects in multilayered media. A novel and efficient method for GFs evaluation is proposed, which is based on integrating the Sommerfeld integrals along SDP on angular spectrum plane. In addition, another efficient approach, namely the spatial tabulation and interpolation, for GFs evaluation are introduced into MoM solving.Based on the efficient evaluation methods of GFs, the MoM procedure based on the RWG basis functions are used to solve the MM-MPIE and the pivotal techniques are investigated, including calculation of incident field, treatment of singular integral,...