An RWG basis function based near- to far-field transformation for 2-D triangular-grid finite difference time domain method

A near- to far-field transformation (NTFT) based on the Rao-Wilton-Glisson (RWG) basis function is proposed for a 2-D triangular-grid FDTD method. The surface equivalence theorem is applied and the equivalent current density, J_z in the TM_z case or M_z in the TE_z case, on the radiation contour is interpolated by using RWG basis functions. The interpolation is valid for the NTFT in either the time or frequency domain. Formulations for the interpolation scheme and the NTFT are presented for the TM_z case. The scattering by an infinite dielectric circular cylinder due to an electric line source is simulated by using the triangular-grid FDTD as well as the proposed NTFT. Numerical results in both the time domain and frequency domain are demonstrated and verified by comparison with analytical solutions.