Application of curvilinear basis functions and MLFMA for radiation and scattering problems involving curved PEC structures

The curvilinear surface and wire basis functions have been applied to solve radiation and scattering problems of various shapes of curved metallic structures with the method of moments. However, a suitable form of junction basis function that can connect the curvilinear wire and the curvilinear Rao-Wilton-Glisson (RWG) surface basis functions has not been found. We present a novel curvilinear junction basis function that can fill the gap. The convergence tests reveal that the curvilinear junction basis function, in conjunction with curvilinear wire and surface basis functions, can reduce the radar cross section (RCS) error by one order of magnitude more than their reduced linear forms for a curved structure. The curvilinear basis functions are applied to solve the radiation from wire antennas attached to curved surfaces. We will demonstrate that the curvilinear basis functions with the multilevel fast multipole algorithm can significantly reduce the computational resources for simulating electrically large objects with curved features.