A multilevel fast multipole algorithm(MLFMA),based on fast multipole method(FMM),is implemented with aggregation,translation and disaggregation stages to optimize computational complexity.Local interpolations are required in aggregation and disaggregation stages of MLFMA in order to match sampling rates of radiated and incoming fields in consecutive levels.A conventional one-step method is decomposed into two one-dimensional interpolations applied successively.Due to significant acceleration in processing time,the proposed two-step method is especially useful for large-scale objects discretized with millions of unknowns.

A hybrid method of physical optics and time domain integral equation(PO-TDIE) is presented to analyze antenna electromagnetic compatibility(EMC) on electrically large platform.General formulation and computational complexity are deduced in detail.Numerical results show that the computational cost is reduced obviously compared with classical marching-on in time(MOT) solver.The hybrid method could be effectively applied in EMC analysis.