Edge currents on metal strip gratings

We present a rigorous analysis of current distribution induced on metal strip grating by an incident plane wave. The grating is characterized by a complex permittivity, with a large imaginary part to account for the finite conductivity of the metal strips. Such a scattering problem is formulated by the method of mode matching to determine the scattered fields everywhere, so that the volume distribution of the current within a metal strip can be explicitly obtained. In particular, in the case of TE-mode incidence, edge currents on the metal strips are examined, with respect to the conductivity and thickness of the grating as well as the incident wavelength. Our results agree well with those of the quasi-static approximation in the low-frequency limit, while noticeable deviations are observed in the high-frequency end.