Research On Rigorous Modeling And High Efficient Algorithms For 3D EM Scattering By Large Body With Open Cavities

The problem of rigorous modeling and high efficient algorithm for the scattering by the electrically large complex body with open cavities has been studied in this dissertation. It has been divided into three sub problems: the first problem is to calculating the scattering by the outer surface of this body; the second problem is to solve the scattering by the cavities of this object; while the third problem is to couple the first problem with the second problem and then calculate the total scattering by the whole body. For the first problem, FMM and MLFMA with the complexity of O(N拁) and O(N log N) have been studied extensively in this paper. For the second problem, the Connecting Scheme (CS) has been described. For the last problem, a new technique-Generalize CFIE has been presented and applied to solve it successfully. At the beginning of the dissertation, the background, the meaning and the main contribution of the research work have been introduced. Subsequently, methods of frequency domain for electromagnetic scattering problems have been introduced roundly. At first, the crux techniques of the basic method for resolving the integral equation- Method of Moment have been studied. They are: geometrical modeling of the object, choosing of basis functions and testing functions, treatment of singularity of integral equations, and remediation of fake solution for the reason of the resonance of a closed body. Based on MoM, a series of methods for speeding up the solution of the Mono-static RCS have been inU~oduccd. They are: method of the basis wave exciting, matrix block-diagonal conditioned method and method of successive trial solution with phase conecting. By using these methods, the speed of Mono-static RCS solution has been radically accelerated. All these have laid the foundation for further research. Aimed at resolving the scattering by the outside surface (excluding the inner wall of cavities but including the aperture抯 surface of cavities) of the object containing cavities with high efficient solution, extensive study of the fast multipoLe method (FMM) and multilevel fast multipole algorithm (MLFMA) has been carried out. At first, the principles of FMM and MLFMA have been described. Where after, the complexity of calculating has been studied. Subsequently, V ? Ab~m~ the optimization for the calculating and staring of invanance terms has been implemented, and hence, the angle invariance characteristic of translation-terms has been presented here. For the sake of calculating the scattering by the cavities of the object, we have introduced a high efficient algorithm for cavit~?problems-Connecting Scheme (CS) based on boundary integral equation and generalized network principle. By using this method, the scattering effects by cavities with different shapes have been studied. Based on all the research works mentioned above, a new technique-Generalized CFIE has been derived and applied for the problem of the scattering by electrically large body with opening cavities. It has combined with MLFMA and CS and used to resolve this problem successfully. At last, as the extra research work of this dissertation, the parallel algorithm of MLFMA has been researched. All the numerical results listed in this dissertation have demonstrated the validity a...