Wideband equivalent circuit for non-aligned 1-D periodic metal strips coupled gratings

Micro-structured metallic devices are used extensively to control the transmission and absorption of electromagnetic waves in the optical, infrared, THz, and microwave domains. The simplest geometry of this class consists of arrays of metal strips printed on a dielectric substrate. The combination of two closely spaced structures of this kind has been proposed to provide control using electrically ultra-thin devices. Models of this kind of structures have been developed for highly symmetrical configurations by means of equivalent circuits that include transmission lines to account for propagating waves and lumped elements to account for high-order diffracted fields. In this contribution we present a wideband equivalent-circuit model to describe the scattering of a set of two coupled non-aligned slit gratings printed on dielectric slabs of arbitrary thickness. The lack of a symmetry plane in such structures is the distinctive feature that has been incorporated in the present analytical model.