Abstract: In order to solve EMC problems for multiple antennas mounted on airborne platforms with limited computer resources, a multilevel fast multipole algorithm (MLFMA) with adaptive number of levels is implemented based on Electric Field Integral Equation(EFIE). For the analysis of coupling between antennas, more reasonable arbitrary isolation is adopted instead of traditional isolation. BiCGStab(l) combined with near-field preconditioner is employed which improves efficiency of the MLFMA. Radiation pattern and isolation of ultra-shortwave antennas on a full-scale Boeing 747 aircraft model are obtained and discussed.