Guided-Wave Properties of Slow-Wave Substrate-Integrated Waveguide Patterned with Non-Uniform Metasurface Unit Cells with Various Degrees of Rotation

A novel slow-wave waveguide structure is proposed, the guided-wave properties of which can be controlled by the rotation of nonuniform metasurface elements loaded on the surface of the substrate-integrated waveguide. The proposed nonuniform metasurface unit cell can exhibit anisotropic guided-wave parameters of interest, i.e., equivalent permittivity and permeability along the transverse direction that are different from those along the longitudinal direction. Such characteristics suggest different propagation behaviors along different directions. Therefore, the equivalent permittivity and permeability change as the proposed nonuniform cross-unit cell rotates through various angles, which would modify the guided-wave properties as well. In this way, the cutoff frequency and phase constant of the proposed anisotropic SW-SIW can be controlled flexibly by rotating the patterned metasurface unit cells over different angles. Several SW-SIW experimental prototypes with different rotation angles are implemented, and their respective measured results are in good agreement with their simulated counterparts. Thereby, the proposed method can provide more flexibility for designing and controlling an anisotropic SW-SIW.