A Novel Leaky-Wave Antenna Based on Spin Photonic Topological Metasurface

The article discusses a leaky-wave antenna that employs spin photonic topological insulators, aiming to achieve broadside radiation-an outcome that is usually challenging for these types of insulators. Spin photonic topological insulators represent a new class of metasurfaces that show potential for both guided and radiative applications. A notable feature of these structures is their ability to resist backscattering while navigating sharp turns in their propagation path. One configuration explored for these metasurfaces consists of hexagonal complementary unit cells. These unit cells reveal different properties depending on whether they are arranged in a zig-zag or armchair configuration. A new X-band leaky-wave antenna has been developed using the armchair arrangement, which offers several advantages over the zig-zag configuration. Additionally, research has focused on establishing proportional coupling between the topological structure and a classical transmission line. Despite the design featuring an unbalanced CRLH metasurface, it can effectively radiate in both backward and forward directions while maintaining robust performance at broadside. An evaluation of the leakage factor for this structure indicates that its exceptionally low value is responsible for its superior performance compared to other unbalanced CRLH metasurfaces, which do not display similar capabilities. This proposed low-profile antenna illuminates both sides of the structure symmetrically, offering a scanning range of 53 degrees and a bandwidth of 2.7 GHz.