Abstract: The fast mutipole method (FMM) and multilevel fast-multipole algorithm(MLFMA) are investigated first for analyzing the radar cross section from large and complex structure objects fast and effectively. And the incomplete LU factorization (ILU) method is employed to reduce the iterative times while the fast algorithms are used. The fast algorithms combine with the ILU to make the simulation speed improve largely. Then the emphasis was put on simulating and studying the RCS from a aircraft of special structure. Theoretical results are very useful for investigating this type of aircraft.

Key words: electromagnetic scattering, method of moment, fast mutipole method(FMM)