Half-space Electromagnetic Scattering And Its Fast And Efficient Algorithm To Study

Numerical analysis methods for electromagnetic radiation and scattering by objects in half-space have important need in many applications such as integrated modeling of radar targets and environments, rader sensing of scattering from a target situated above or below the ground,such as vehicles near the ground, mines and unexploded ordnance(UXO).Usually, the half-space is treated as one kinds of boundary condition in numerical analysis methods, such as FDTD method and FEM method. As known to all, the computation precision becomes hard to assure because of the boundary condition and the discreate of space steps leads to huge number of unknowns which need more computer resource. Since the integral equation methods can conquer such difficults. The fast multipole method (FMM) and multi-level fast multipole algorithm (MLFMA) is used to analysis of electromagnetic scattering property for electrically large objects broadly. The basis of the two methods is the expansion of Green function, but the Green function is half-space is different from the Green function in free space. This difference leads to the aggregation, translation, and disaggregation become different from the items in half-space. However we can utilize the ideas of FMM and MLFMA in free-space to develop the algorithm in half-space.The Dyadic Green function in half-space is discussed firstly in this paper as the Dyadic Green function is the foundation of integral equation methods. Then the matrix forms of EFIE and MFIE in half-space are given. As the most important parts of this paper, the fast multipole method (FMM) and multi-level fast multipole algorithm (MLFMA) in half-space are given. Further more, the Local Iteration in MLFMA is dicussed as the final parts.The correctness and accuracy of FMM and MLFMA in half-space are studied in this paper. The numerical results in this paper agree well with the the results of the third part business software. This work supports an efficient solution scheme for electromagnetic scattering of large scale targets.