2-D Artificial Media With Forced Refraction

This letter investigates the propagation of guided waves along two identical metal gratings symmetrically lying on both sides of a dielectric substrate. Previously, investigations of the properties of such waves had been restricted to odd waves, equivalent to waves in a grounded dielectric substrate. Averaged equivalent boundary conditions (EBCs) for the fields at the grating are used to simplify the analysis. Even waves equivalent to waves in a substrate grounded by a perfect magnetic wall are the focus of this letter. The dominant even wave is studied with the help of an electromagnetic Ansys HFSS simulation and EBCs. EBC analysis is referred to strip gratings in the homogenization limit (i.e., with a subwavelength period). Both methods demonstrate that the investigated structure in some frequency range has the properties of a two-dimensional medium with forced refraction. The results have the potential for applications in microwave and millimeter-wave planar quasi-optical lens antennas.