Abstract: To gain a precise radar cross section (RCS) scattering from three-dimensional objects efficiently and stably, the convergence algorithm is adopted which integrates conjugate grads (CG) algorithm combined field integral equation (CFIE) and multilevel fast multipole algorithm (MLFMA). Based on traditional MLFMA, the effect on calculation precision caused by node number used in the two-dimensional Lagrange interpolation is investigated in detail, and interpolation method is improved which chooses different node number at different levels. This article presents a method that adopted different precision control at different levels for truncation number calculation. The impact of symmetry of sparse matrix on the memory used in calculation is analyzed, and the selection of iterative initial value for magnetic field integral equation (MFIE) is discussed. The improvementscan enhance the precision and efficiency of calculation notably and reduce memory, as illustrated by the numerical results. They can meet the algorithm requirements of electromagnetic scattering for complex three-dimensional targets.

Key words: electromagnetic scattering, multilevel fast multipole algorithm(MLFMA), Lagrange interpolation, truncation number, radar cross section (RCS)