Fig. 1. Pathloss analysis for reflection and transmission RIS^[40]： (a) Tx and Rx are on the same side of the RIS; (b) Tx and Rx are on opposite sides of the RIS; (c) RIS-assisted wireless communication system^[41-42]; Free-space path loss measurement system for measuring the amount of power reflected from the RIS for different configurations of , , and ^[41-42]: (d) Diagram; (e) Photograph 具备反射和透射功能的信息超表面路径损耗分析^[40]：（a）发射机和接收机在信息超表面的同一侧；（b）发射机和接收机在信息超表面的两侧；（c）信息超表面辅助的无线通信系统^[41-42]；用于测量不同 ， ， ，和 配置下自由空间路径损耗的测量统^[41-42]：（d）原理图；（e）实测照片

Fig. 2. (a) Equivalent transmission line model for the unit cell of the RIS^[43]; (b) Angle-dependent phase shifter model for the unit cell of the RIS^[44]

Fig. 3. End-to-end mutual-coupling-aware communication model^[45]

Fig. 4. (a) The aluminium cavity experimental setup incorporating RIS coated on the wall in order to enrich multipath scattering in a LoS MIMO wireless communication link at the WiFi frequency 2.47 GHz^[52]; (b) The evolution of the effective rank of the LoS channel matrix (red for , blue for , and orange for ) over the number of algorithmic steps. Benchmarks for Rayleigh fading and perfect channel orthogonality are also included^[52]; (c) Distributed RISs-assisted strong LoS mmWave communication systems^[53]（a）信息超表面覆盖的铝腔实验装置，用于增强LoS MIMO无线通信链路在2.47 GHz WiFi频率下的多径散射^[52]；（b） LoS MIMO（红线表示 ，蓝线表示 ，橙线表示 ）的有效秩随着算法迭代步骤的演进。图中包含瑞利衰落信道和完美正交信道作为比较基准^[52]；（c）分布式信息超表面辅助的强视距毫米波通信系统^[53]

Fig. 5. Non-periodic coding metasurfaces and their far-field patterns^[63]. (a) Symmetric coding; (b) random coding, and (c) the relationship between the geometrical and physical entropies; (d) Schematic of information relation between the metasurface and its radiation pattern^[64]

Fig. 6. (a) Experimental scenario of the BFSK wireless communication system based on information metasurface with transmission process described on the right^[54]; (b) The received messages by the BFSK wireless communication system; (c) The instantaneous experimental results for the receiving spectrum.; (d) The relation diagram between the bit error rate and the transmitting power of the feed antenna at different communication distances and incident angles

Fig. 7. (a) Photograph of the QPSK wireless communication system based on the information metasurface^[55]; (b) The dependence of the measured constellation diagram of the QPSK wireless communication system on the message transmission rate at receiving terminal; (c) Photograph of the 8 PSK wireless communication system based on the information metasurface^[56]; (d) The signal-to-noise ratio (SNR) and the corresponding BER at the receiver of the 8 PSK transmitter and the conventional SDR-based transmitter

Fig. 8. (a) The measured constellation diagrams for QPSK, 8 PSK and 16 QAM^[57]; (b) Photograph of the mmWave 256 QAM wireless communication system based on the information metasurface^[58]. The 256 QAM constellation diagrams with a frequency interval of 78.125 kHz at (c) f_c=27 GHz, (d) 28 GHz, and (e) 29 GHz, respectively

Fig. 9. (a) The schematic diagram of transmitting digital message directly via the farfield change of the information metasurface^[59]; (b) The original image to be transmitted for testing the performance of the prototype system; (c)-(e) The received image: (c) without barrier in the channel, (d) with barrier in the channel; (e) The received image after running the self-adaption program with barrier in the channel

Fig. 10. (a) The direct transmitted 8 phase codes in three channels and (b) corresponding near-field patterns^[60]; (c) Schematic of the experimental setup of the metasurface-assisted massive backscatter wireless communication^[61]; (d) Amplitude distributions of the 8 coding patterns in the metasurface-assisted massive backscatter wireless communication; (e) BPSK constellation results of single-channel, double-channel and three-channel; (f) Individual monochrome and synthesized full-color images transmitted from Alice to Bobs

Fig. 11. (a) Experimental scenario of the dual-channel wireless communication system based on information metasurface^[62]; (b) Measured radiation patterns of the four coding patterns for dual-channel direct information transmissions