Glide-Shifted Dielectric Gratings for Independent Leakage and Phase Tuning in Leaky-Wave Antennas

This paper presents a comprehensive analysis of grounded glide-shifted dielectric periodic structures and their application to the design of leaky-wave antennas (LWAs). A modified Rigorous Coupled Wave Analysis (RCWA) framework has been developed to calculate the dispersion characteristics of these periodic structures (containing glide-shifted layers) and decrease the computational complexity. A method for solving the derived dispersion equation is discussed that enables differentiation between proper and improper radiating modes. The proposed unit cell geometry, featuring a grounded two-layer dielectric grating (identical gratings with glide-shift between them) demonstrates intriguing dispersion characteristics governed by the ratio of the thicknesses of the two layers. These characteristics include the first stopband closure and the possibility of precise control over the leakage rate while maintaining minimal variation in the phase constant. Numerical validation using the Legume-GME package and CST Eigenmode Solver confirms the accuracy of the method. Building on this analysis, the framework is applied to design LWAs with tapered aperture illumination, with a dielectric Mikaelian lens used as a surface wave launcher. This work underscores the critical role of glide symmetry and analytical modeling in advancing periodic structures, with LWAs emerging as a practical outcome for tailored microwave and millimeter-wave applications.