Transmission and reflection characteristics of slightly irregular wire-grids with finite conductivity for arbitrary angles of incidence and grid rotation

In the first half of this paper, an efficient method to calculate transmission and reflection characteristics of wire-grids consisting of periodic arrays of cylindrical conductors for arbitrary directions of incidence is presented by extending exact theory of wire-grids proposed by Yasumoto et al. In the latter half of this paper, an approximate calculation method for wire-grids with slight random irregularity in their spacings between wires is proposed by treating the irregularity as a small perturbation to the theory for regular grids. A comparison with preliminary measurements for actual wire-grids in millimeter- and submillimeter-wave regions demonstrated that this method is effectively applicable to wire-grids whose irregularity is not too much. Index Terms--Electromagnetic reflection, electromagnetic scattering by periodic structures, submillimeter wave devices, submillimeter wave measurements, wire grids.