A Novel Method to Analyze Electromagnetic Scattering of Complex Objects

TLDR

The authors propose using the finite‑difference time‑domain (FD‑TD) method to accurately compute electromagnetic scattering from arbitrarily shaped, highly complex metal or dielectric objects illuminated by a plane wave. They first compute near total fields inside a rectangular volume enclosing the object with FD‑TD, then apply the electromagnetic‑field equivalence principle at a virtual surface to convert the tangential near‑scattered fields into far‑field results, and validate the approach on two canonical 2‑D objects by comparing surface currents, near/far scattered fields, and radar cross sections. The FD‑TD approach achieves current and field magnitudes within ±2.5 % and phase within ±30° of method‑of‑moments predictions at virtually every point, including shadow regions.

Abstract

The finite-difference time-domain (FD-TD) method is proposed as a means of accurately computing electromagnetic scattering by arbitrary-shaped extremely complex metal or dielectric objects excited by an external plane wave. In the proposed method, one first uses the FD-TD method to compute the near total fields within a rectangular volume which fully encloses the object. Then, an electromagnetic-field equivalence principle is invoked at a virtual surface of this rectangular volume to transform the tangential near scattered fields to the far field. To verify the feasibility of this method, the surface currents, near scattered fields, far scattered fields, and radar cross section of two canonical two-dimensional objects are presented. For these cases, it is shown that the FD-TD method provides magnitude of current and field predictions which are within ± 2.5 percent and further phase values within ± 30 of values predicted by the method of moments ( MOM) at virtually every point including in shadow regions.