Abstract: The Original Generalized Image Method can only deal with four aspect symmetric scattering body.On the basis of the original GIM,a developed method termed Extended GIM is proposed.The Extended GIM can save a great deal of calculation time and storage of computer when useing it for dealing with the scattering sturcture of higher symmetry than the four aspect symmetric one.A six-aspect symmetric example is also given.

Key words: Electromagnetic scattering, Extended boundary condition, Moment method