Fig. 5.

A sub-wavelength dielectric rod waveguide with dual-layer metasurface coatings. Simulated and measured co-polarized (T _xx) and cross-polarized (T _yx) transmission between the transmitting and receiving probes for the inner coating layer a without and b with twisting perturbation. The insets show the configuration and the snapshots of the vector electric field distribution at 3.3 GHz in the x-y planes at two different positions along the axis of the rod when excited by an x polarized probe. c Measured state-of-polarization patterns of the Teflon rod waveguide with a dual-layer coating for the inner metasurface layer with and without twisting perturbation. d Measured rotation angle and the rotation angle per wavelength as a function of frequency