Evaluation of Fourier cosine/sine transforms using exponentially positioned samples

Abstract

Abstract The digital filter technique using exponentially positioned samples has been widely used in evaluating Hankel transforms. However it is not so widely used in evaluating Fourier transforms (FT). Published actual filters for FT evaluation are rather limited. We therefore present filters in lengths: 21, 61 and 101, which may be useful in evaluating FT for calculating e.g., the electromagnetic fields from a line source and from a dipole source, etc. It is shown that the filter technique can be more efficient (i.e., using fewer samples) than using digital Fourier transform (DFT) in evaluating FT related to 2D and 3D Green's functions.