FDTD method for the scattered-field equation to calculate the radar cross-section of a three-dimensional target

摘要

A discrete finite-difference time-domain (FDTD) method based on Maxwell's equations is proposed to solve the scattered-field equation for dispersive media. The equations for the scattered field in a plasma medium are first derived, then used to calculate the radar cross-section (RCS) of three-dimensional targets, viz. a plasma sphere and a rectangular plate. When using such an FDTD method to compute the far-field scattering characteristics of a target, the near- to far-field transformation technique is generally required, which involves artificial setting a connection boundary between the total and scattered field in the computational space in order to calculate the latter and thereby the RCS of the target. This connection boundary must be set separately and appropriate computational grids added. However, by discretizing the Maxwell's equations describing the scattered field, the resulting field in the computational space is already the scattered field and can be used directly to calculate the far-field properties of the target. In this way, the additional processing for the edge of the scattered field and computational space is avoided. Numerical calculations herein show that this FDTD approach for the scattered field is universal to some extent, being suitable for not only homogeneous but also dispersive media.