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We propose and implement a novel 1-bit coding metasurface that is capable of focusing and steering beam for enhancing power transfer efficiency of the electromagnetic (EM) wave-based wireless power transfer systems. The proposed metasurface comprises 16 × 16 unit cells which are designed with a fractal structure and the operating frequency of 5.8 GHz. One PIN diode is incorporated within each unit cell and enables two states with 180 ° phase change of the reflected signal at the unit cell. The two states of the unit cell correspond to the ON and OFF states of the PIN diode or “0” and “1” coding in the metasurface. By appropriately handling the ON/OFF states of the coding metasurface, we can control the reflected EM wave impinged on the metasurface. To verify the working ability of the coding metasurface, a prototype metasurface with a control board has been fabricated and measured. The results showed that the coding metasurface is capable of focusing beam to desired direction. For practical scenarios, we propose an adaptive optimal phase control scheme for focusing the beam to a mobile target. Furthermore, we prove that the proposed adaptive optimal phase control scheme outperforms the random phase control and beam synthesis schemes.

Recently, the fifth generation of cellular mobile communications (5G) network has been deployed and become pervasive. 5G offers a significant increase in terms of bandwidth and data rate compared to the previous generations. In addition, new technologies such as millimeter-wave (mmWave) technology and massive MIMO (mMIMO), have been proposed to meet the demand. However, some inevitable challenges still exist. In mmWave frequency, path loss and shadowing become more severe due to the radio electromagnetic (EM) wave characteristics. In this paper, we propose the utilization of reconfigurable intelligent surface (RIS) to aid wireless communications to overcome path loss and shadowing issues, by using a compressive sensing-based adaptive beamforming algorithm. To validate the theory, hypothesis, and simulation results, we have designed, fabricated, and conducted experiments with a 1-bit RIS testbed. The results show that the bit error rate (BER) and signal-to-noise ratio (SNR) of the received signal are significantly improved when the proposed RIS is employed. Further, we have also demonstrated a video streaming application aided by the proposed RIS as one of the potential RIS deployment scenarios. The video clip for the video streaming by using the RIS can be seen in [1].

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