Conservative High-Order Modified FDTD (2,4) Method for Electromagnetic Scattering

In this article, we develop the conservative high-order modified finite-difference time-domain (FDTD) (2,4) (CM24) method to solve electromagnetic scattering of objects for the first time. We first establish the CM24 update equations for the electric and magnetic field components near the total-field/scattered-field (TF/SF) boundaries, respectively. In order to inject an incident plane wave into the TF region without leakage, the CM24-based discrete plane wave (CM24-DPW) scheme is proposed. The six 1-D auxiliary grids employed in the CM24-DPW have the same numerical dispersion relationship as the 3-D CM24 grids. Moreover, interpolation errors of field components mapping from six 1-D auxiliary grids to 3-D CM24 grids are eliminated. The field leakage in the SF region simulated by the proposed method is measured at the level of −300 dB. Subsequently, CM24 update equations for the convolutional perfectly matched layer (CPML) are derived. Radar cross sections (RCSs) of the metal sphere and cubic object are calculated to show the higher accuracy of the CM24 method for electromagnetic scattering calculations.