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 theLandKcomponents 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.