Fig. 1. Schematic diagram of the proposed full-space programmable CP metasurface capable of independent control of copolarized reflection for RCP incident waves and cross-polarized transmission for LCP incident waves in real time.

Fig. 2. Geometric shape and structural parameters of the meta-atom. (a) Perspective view of the meta-atom and the equivalent circuit model of PIN diode in ON and OFF states. (b)–(g) Detailed structure and geometric parameters of the meta-atom.

Fig. 3. Simulated surface current distribution with PIN 1 OFF, PIN 2 OFF, and PIN 3 ON. The surface current distribution on the (a) receiver patch and (b) transmitter patch under RCP incidence. The surface current distribution on the (c) receiver patch and (d) transmitter patch under LCP incidence.

Fig. 4. Simulated surface current distribution when PIN diodes are in different working states. The surface current distribution on the receiver patch when (a) PIN 1 is OFF and (b) PIN 1 is ON under the RCP incidence. The surface current distribution on the transmitter patch when (c) PIN 2 and PIN 3 are in ON and OFF states, and (d) PIN 2 and PIN 3 are in OFF and ON states under the LCP incidence.

Fig. 5. Simulated amplitude and phase responses of the meta-atom under different CP incident waves. Reflected (a) amplitude and (b) phase responses of the meta-atom when PIN 2 is in OFF state and PIN 3 is in ON state under RCP incidence. Reflected (c) amplitude and (d) phase responses of the meta-atom when PIN 2 is in ON state and PIN 3 is in OFF state under RCP incidence. Transmitted (e) amplitude and (f) phase responses of the meta-atom when PIN 1 is in OFF state under LCP incidence. Transmitted (g) amplitude and (h) phase responses of the meta-atom when PIN 1 is in ON state under LCP incidence.

Fig. 6. Phase coding patterns and corresponding simulated far-field radiation patterns at 10 GHz. Reflection and transmission phase codes for (a) θr=10° and θt=190°, (b) θr=−20° and θt=180°, and (c) θr=−30° and θt=210° in the yoz plane. (d), (e), (f) Far-field radiation patterns corresponding to the phase coding codes in (a), (b), and (c), respectively. (g) Reflection and transmission phase codes of one reflected beam (θr=0°, φr=0°) and two transmitted beams (θt1=205°, φt1=0° and θt2=205°, φt2=90°), (h) two reflected beams (θr1=25°, φr1=0° and θr2=35°, φr2=225°) and one transmitted beam (θt=205°, φt=45°) under the incidence of feeding horn antenna. (i) Reflection and transmission codes of two reflected beams (θr1=−32°, φr1=0° and θr2=32°, φr2=0°) and two transmitted beams (θt1=165°, φt1=0° and θt2=195°, φr2=0°) under the incidence of plane waves. (j), (k), (l) Far-field radiation patterns corresponding to phase codes in (d), (e) and (f), respectively, in which u=sinθcosφ and v=sinθsinφ.

Fig. 7. Measured far-field radiation patterns in yoz plane at 10 GHz. (a) θr=10° and θt=190°, (b) θr=−20° and θt=180°, (c) θr=−30° and θt=210° under the incidence of feeding horn antenna. (d) (θr1=−32°, φr1=0° and θr2=32°, φr2=0°) and (θt1=165°, φt1=0° and θt2=195°, φr2=0°) under the incidence of plane waves. The scanning pattern in the (e) reflection space and (f) transmission space under the incidence of feeding horn antenna. [Angles in panels (a)–(d) are in degrees.]

Fig. 8. Schematic diagram of the full-space communication system.

Fig. 9. Received constellations and recovered images in reflected and transmission spaces at 10 GHz. (a) The simulated radiation directions of the reflected dual beams are ±15°, while the transmitted beams are 148° and 212°. (b) The QPSK constellation diagram and demodulated images received in the reflection and transmission spaces when the metasurface is working normally. (c) The QPSK constellation diagram and demodulated images received in the reflection and transmission spaces when the metasurface is not working.

Fig. 10. Bias network of the metasurface. (a) Top view (receiver patch layer). (b) Bias network of PIN 1 (layer 3). (c) Bias network of PIN 2/PIN 3 (layer 4).

Fig. 11. Fabricated prototype and measurement results. (a) Top view of the fabricated prototype. (b) Bottom view of the fabricated prototype. (c) Experimental setup of the full-space radiation patterns in an anechoic chamber. The reflected far-field radiation patterns in yoz plane at (d) 9.6 GHz, (e) 10 GHz, and (f) 10.4 GHz. The transmitted far-field radiation patterns in yoz plane at (g) 9.6 GHz, (h) 9.8 GHz, and (i) 10 GHz. The reflected far-field radiation patterns in xoz plane at (j) 9.6 GHz, (k) 10 GHz, and (l) 10.4 GHz. The transmitted far-field radiation patterns in xoz plane at (m) 9.6 GHz, (n) 9.8 GHz, and (o) 10 GHz.

Fig. 12. Workflow diagram and experimental setup of wireless communication systems. (a) Schematic diagram of communication system. (b) Photograph of experimental setup in microwave anechoic chamber (the red dashed box outlines a locally magnified photo and the required experimental equipment is marked with white arrows one by one).