Numerical solution of the horn antenna with complex structure

The integral equation method and the mode matching method has been used as a combined numerical algorithm to simulate the horn antenna with complex structure and electronically large size. The mode matching method is used to depict the excitation and the integral equation method is used to solve the equavalence surface sources. The multilevel fast multipole algorithm(MLFMA) have been used to speed up the matrix-vector multiplication and reduce the memory requirement. The sparse approximate inverse(SAI) preconditioning technique were used to reduce the number of the iteration steps. It has been demonstrated that the method proposed by this paper is able to provide the efficient and accurate numerical solutions for the horn antenna with arbitrary shape and electronically large size.