On the formulation of characteristic mode theory with fast multipole algorithms

To enhance the capability of the characteristic mode analysis (CMA) for electrically large problems, fast multipole algorithms (FMAs) are incorporated into this increasingly popular technique in antenna community. In this communication, an improvement formulation of CMA with FMAs is presented and studied. Numerical results show that the proposed formulation has a better convergence behavior than the previous formulation when it is used for electrically large antenna platforms.