A two-dimensional time-domain near-zone to far-zone transformation

A 2D version of a time-domain transformation useful for extrapolating 3D near-zone finite-difference time-domain (FDTD) results to the far zone is outlined. While the 3D transformation produced a physically observable far-zone time-domain field, this is not convenient for the 2D case. However, a representative, 2D far-zone time-domain result can be obtained directly. This result can then be transformed to the frequency domain using a fast Fourier transform, corrected with a simple multiplicative factor, and used, for example, to calculate the complex wideband scattering width of a target. If an actual time-domain far zone result is required, it can be obtained by inverse Fourier transform of the final frequency-domain result