A higher-order finite element method for computing the radar cross section of bodies of revolution

The finite element method (FEM) is used to compute the radar cross section (RCS) of bodies of revolution (BORs). The FEM described here uses scalar basis functions for the &phis; component of the field and vector basis functions for the transverse component of the field. Higher-order basis functions are used to improve the performance of the FEM code. The mesh is truncated using two methods. The first method is the perfectly matched layer (PML). This method has a number of parameters that must be optimized to obtain good results. Furthermore, the PML must be kept a reasonable distance away from the scatterer, which causes the number of unknowns to be relatively high. To decrease the number of unknowns the iterative absorbing boundary condition (IABC) is proposed. In this method an absorbing boundary condition (ABC) is used as the starting point for the mesh truncation, and then the fields at the mesh truncation are updated by propagating the fields from another surface in the computational domain to the mesh truncation boundary. The IABC allows the mesh truncation to be moved much closer to the scatterer without corrupting the final results. A comparison is given between the results of the PML and the IABC, and it is determined that using higher-order basis functions with the IABC is more efficient in terms of the number of unknowns and the CPU time than the PML.