RIS Assisted Near Field Communication in Sub-6 GHz Band: Experimental Perspective

A testbed for a reconfigurable intelligent surface (RIS) assisted communication system is implemented and optimized for near-field scenarios in the sub-6 GHz band. The RIS features a 400-element reflectarray, measuring 508 mm $\times 508$ mm (aperture diameter 718.3 mm, approximately $8.97\lambda \times 8.97\lambda $ at 5.3 GHz), built with low-cost FR-4 material and PIN diodes to achieve 1-bit phase control. Operating within the near-field region (Fraunhofer distance $d_{F}\approx 18.2$ m), the system manipulates spherical wavefronts to enable precise beam steering and signal enhancement significantly in indoor environments. Experiments demonstrate a 12-15 dB gain in received power, stable beamforming at multiple angles, and wireless communication with a peak throughput of 36.70 Mbps and signal-to-interference-plus-noise ratio (SINR) of 27.22 dB.