Diffraction of electromagnetic waves by a two-dimensional periodic waveguide-dielectric array

An analysis is presented of electromagnetic-wave diffraction by a two-dimensional periodic waveguide array covered by several layers of an inhomogeneous dielectric. For the case of quasi-periodic excitation of the array, the solution is obtained by the method of projection field matching in planes of junctions of longitudinally homogeneous regions. An orthonormal system of eigenvector functions of the transversely inhomogeneous Floquet channel is used as the basis in the two-dimensional periodic dielectric structure. The effectiveness of the proposed algorithm is demonstrated by a calculation of the coefficient of reflection of an incident wave from the aperture of an array of circular waveguides, matched with free space via stepwise dielectric rods. It is shown that the use of stepwise dielectric rods for the matching of waveguide antenna arrays is more effective than the use of dielectric cylinders jutting from the waveguides.