Fig. 1. Passive folded reflectarray metasurface prototype. (a) RCS reduction for CP wave^[38]; (b) RCS reduction for LP wave^[39]; (c) OAM beam generator^[40]; (d) Airy beam generator^[41]

Fig. 2. Passive folded transmitarray metasurface. (a) Circularly-polarized folded transmitarray metasurface^[42]; (b) Ⅱ-type folded transmitarray metasurface prototype^[46]

Fig. 3. Active folded metasurface. (a) Programmable folded metasurface for beam scanning^[48]; (b) Measured radiation pattern; (c) Active folded metasurface for OAM beam generation^[49]; (d) Near-field amplitude and phase distribution for l=+2; (e) Active folded metasurface for beam steering^[50]; (f) Simulated and measured normalized radiation patterns

Fig. 4. Passive F-P metasurface. (a) Low-scattering F-P coding metasurface^[51]; (b) F-P metasurface for RCS reduction^[52]; (c) F-P metasurface for 2D holographic imaging^[53]; (d) F-P metasurface for dual circularly polarized radiation^[54]

Fig. 5. Active F-P metasurface. (a) Frequency reconfigurable F-P metasurface^[55]; (b) Dual-band reconfigurable F-P metasurface^[56]; (c) F-P metasurface for in-band RCS reduction^[57]; (d) Reconfigurable scattering patterns F-P metasurface^[58]

Fig. 6. Passive leaky-wave metasurface. (a) Wide-angle uniform leaky-wave metasurface^[59]; (b) Multilayer uniform leaky-wave metasurface^[60]; (c) Dual-functional holographic metasurface^[66]; (d) Multiplexing tensor holographic metasurface^[67]

Fig. 7. Active leaky-wave metasurface. (a) Sideband-free leaky-wave metasurface^[68]; (b) Fundamental-frequency beam scanning; (c) Multi-harmonic independent control; (d) Dynamic near-field focusing holographic metasurface^[69]; (e) Dynamic beam holographic metasurface^[70]

Fig. 8. Passive radiation-type metasurface. (a) Integrated coding-metasurface^[75]; (b) Phase- and polarization-modulated radiation-type metasurface^[76]; (c) Amplitude-, phase- and polarization-modulated radiation-type metasurface^[77]; (d) Complex-amplitude modulated radiation-type metasurface^[79]

Fig. 9. Active radiation-type metasurface. (a) Programmable radiation-type metasurface^[80]; (b) Radiations and reflections integrated metasurface^[81]