Fast PO-MM Techniques And Their Applications To The Analyses Of Wire Antennas On Complex Electrically-large Platforms

Fast algorithms combined with the hybrid physical optics -method of moments (PO-MM) and their applications are investigated in this dissertation. In recent years, the analyses of radiation of wire antennas mounted on electrically-large and complex shaped PEC platforms and the related electromagnetic compatibility (EMC) problems have aroused much attention in the community of EM Engineering. Hybrid PO-MM algorithm is suitable to solve such problems. Firstly, based on the spectrum characteristics of matrix equation deduced from PO-MM, a new kind of near-field precondition method is adopted to amend the condition of the matrix which can enhance the convergence speed greatly when it is combined with GMRES to obtain the solution of the matrix equation. Secondly, considering that the value of impedance matrix elements varies slowly with frequency, a kind of rational interpolation method is implemented into PO-MM, by which the impedance matrix in all other frequency sample points can be rapidly calculated out with the impedance matrix elements only in a few frequency sample points in a given frequency band. When PO-MM is used to handle wide-band electromagnetic problems, this impedance-matrix-interpolation technique can improve the efficiency greatly, which is significant in practical engineering applications. At last, on the basis of the modified fast PO-MM mentioned above, fast far field approximation is applied to calculate the discrete current in PO area. In this way, the computation efficiency has also been improved apparently. Many examples are presented in this thesis and the numerical results verified the accuracy and efficiency of the proposed fast PO-MM techniques.