Exact solution to the problem of the diffraction of an obliquely incident plane wave by a grating

An exact solution is obtained for the problem of the diffraction of a plane wave by a grating consisting of infinitely thin ideal conductors periodically arranged along a straight line. The length of the conductors is equal to the distance between them, and the angle of incidence is arbitrary. The problem is reduced to the Riemann matrix problem, and the spectrum of plane waves reflected from the diffraction grating is obtained.