Novel Buffa-Christiansen Functions for Improving CFIE With Impedance Boundary Condition

A novel kind of Buffa-Christiansen (BC) functions is developed for improving the surface combined field integral equation with impedance boundary condition (CFIE-IBC) from three-dimensional imperfectly conducting objects. With difference from the original BC function in wide use, the novel BC function is dimensionless as the RWG function, which makes the L and K components of the resulting matrix element from the CFIE-IBC dimensionally homogeneous. As a result, the eigenvalue condition number of the matrix is very low, which leads to a fast-convergence solution whether the surface impedance is low or high. The CFIE-IBC with the novel BC function is combined with the overlapped domain decomposition method for reducing the memory requirement. In its application to the multilevel fast multipole algorithm, the far-field interactions can be simplified for reducing the computational cost.