The determination of the effective radius of a filamentary source in the FDTD mesh

This paper proposes a rigorous method for determining the effective radius, r(eff), of a single axial field component, E-z or H-z, in a two-dimensiona l (2-D) TMz or TEz FDTD grid, respectively. The method is based upon matchi ng FDTD results for a filamentary field source with the analytical Green's function in two dimensions. We find that r(eff) approximate to 0.2 grid cel ls over a wide range of grid resolutions. Further, our findings vividly dem onstrate the nondissipative nature of the Yee algorithm even for very coars e grid resolutions.