Shaping flattened scattering patterns in broadband using passive reconfigurable intelligent surfaces for indoor NLOS wireless signal coverage enhancement

A novel Passive Reconfigurable Intelligent Surface (PRIS) with 100 � 100 elements, which is shaped to scatter flattened patterns in broadband, is presented to enhance the signal coverage of the indoor Non-Line-of-Sight (NLOS) area for 5G millimeter wave (mmWave) wireless communications. The signal from the base station antenna as a primary source can be deflected to the NLOS area by the proposed PRIS with a flattened scattering pattern that is insusceptible to being blocked. The broadband meta-atom, realized by the framed four arrow branches, operates from 24 GHz to 30 GHz. The genetic algorithm is applied to optimize the phase shift distribution of PRIS for a shaped pattern. Combining full-wave simulation and 3D ray-tracing simulation, the signal coverage is computed in an indoor L-shaped corridor scenario for 5G mmWave wireless communications. To verify the design, the proposed PRIS is further manufactured and tested. The experimental results reveal that the signal enhancement in the NLOS area by the proposed PRIS with the flattened scattering pattern is superior to the conventional design.