Microwave Surface-Wave Nonreciprocity Using Low-Profile Ferrite Metasurfaces

This letter presents a metasurface-based approach to achieve nonreciprocal control of surface wave propagation using compact and integrable structures. Two configurations are investigated: a 3D asymmetric metasurface employing biased ferrite elements, and a low-profile configuration combining ferrite with an electromagnetic bandgap (EBG) array. Full-wave simulations and experimental measurements confirm that both structures exhibit direction-dependent surface wave suppression around 6.5 GHz, corresponding to the gyrotropic response of the ferrite. The experimental model, constructed with planar unit cells and verified using a curved-surface measurement jig, demonstrates strong agreement with the simulation results. Unlike conventional nonreciprocal structures requiring bulky geometries or complex biasing, the proposed metasurfaces offer simple, versatile designs suited for integration into dense platforms such as UAVs and aircraft, where minimizing surface wave crosstalk between antennas is critical. The demonstrated method provides a new pathway for low-profile, frequency-tunable nonreciprocal surface wave control using classical gyrotropic media.