Fig. 1. Schematic configuration of the proposed intelligent metasurface.

Fig. 2. The proposed meta-atom and its symmetric operation mode. (a) Top view and (b) perspective view. In this work, the following parameters are: w=0.8, R=3.6, b=1.5, r=1.2, P=9 (all in millimeters), and α=21°, β=160°. (c) and (d) are the surface current distributions under x- and y-polarized wave illumination, respectively.

Fig. 3. The reflection characteristics of the meta-atom. Simulation reflection coefficients versus frequency for orientation angle (a) α=0° and (b) α=45° shined by LP plane wave excitations. Amplitude and phase of the reflected coefficient (c) rxx and (d) ryy as functions of parameter α at 14 GHz. (e), (f) Amplitude and phase difference of the rxx and ryy as a function of α and frequency.

Fig. 4. Full-polarization metasurface for double beam deflection. (a) Configured 1-bit coding elements working independently for phase control of linear and circular polarizations. (b) Required phase distribution. (c) The theoretical and simulated 2D normalized scattering patterns under the x-polarized wave in the yoz plane at 14 GHz.

Fig. 5. Poincaré sphere representation of some exemplary states from A to E, corresponding to RCP, EP, x-LP, LCP, and y-LP, respectively. The simulated far-field radiation patterns represent the co-polarized beam under the normal incidence of the full-polarization metasurface with the SOP from (a) to (e).

Fig. 6. Sensing module for the incident polarization detection. Prototype and measured output DC voltages to (a)–(c) LPDA and (d)–(f) CPDA, respectively.

Fig. 7. Intelligent metasurfaces achieve different EM functions for different polarized incidences. The phase distribution of function and its simulated results for (a) beam scanning under x-polarization, (b) specular reflection under y-polarization, (c) diffuse scattering under LCP, and (d) vortex beams under the RCP incident wave. The columns i and ii are phase distributions and simulated 3D scattering patterns. The column iii contains 2D scattering patterns and the phase patterns of the vortex beam. The column iv shows the simulated normalized E-field patterns on the yoz plane and the monostatic RCS reductions from 8 to 24 GHz.

Fig. 8. The experimental setup in an anechoic chamber. (a) Photograph of the fabricated sample. The inset of the picture shows a single meta-atom whose ground plane is removed for a clear view. (b) Photograph of the measurement setup in the microwave anechoic chamber.

Fig. 9. Experiments with the fabricated intelligent metasurface. Measured and simulated 2D normalized scattering patterns in the yoz plane for (a) x-LP, (c) y-LP, (f) RCP incidence at 14 GHz, and (d) LCP incidence at 19 GHz. (b) The normalized 2D pattern within 8–24 GHz in the yoz plane for x-LP incidence. (e) Comparison of the measured and simulated RCS reductions for LCP incidence.

Fig. 10. Three-dimensional radiation patterns at the different frequencies of 9 GHz, 15 GHz, and 21 GHz for (a) x-LP, (b) y-LP, (c) LCP, (d) RCP, and (e) EP incident waves.

Fig. 11. Basic structure of the LPDA. (a) Top view of the antenna, (b) bottom view of the antenna. The optimized parameters are a1=4.9, b1=5.3, l1=40, and w1=25.5, all in the unit of millimeters.

Fig. 12. The basic structure of the CPDA. (a) Top view of the antenna, (b) bottom view of the antenna. (c) Equivalent circuit models of the PIN diodes in the OFF and ON states. (d) Simulated S11 of the CPDA. (e) Phase difference of the two parts. The optimized parameters are a2=4.8, b2=9.1, n=13.7, m=16.35, l2=55, w2=19.7, r=5.44, all in the unit of millimeters, and β=28.2°.

Fig. 13. Scattering patterns of the designed vortex beam generator at (a) 9 GHz, (b) 13 GHz, (c) 17 GHz, and (d) 21 GHz under RCP incidence, respectively. The left panels show the amplitude of the scattering patterns while the right panels show the phase patterns of each vortex beam.

Fig. 14. Measured results of the near-field intensity distribution, phase distribution, and mode spectra of OAM beams with mode (a) l=1 and (b) l=−1.