Advancing RIS Beamforming Efficiency: Moving Beyond Diagonal Matrix Techniques

Optimizing wireless propagation channels is essential for advancing future communication technologies, particularly in dynamic vehicular environments where high vehicle mobility is a challenge. This paper introduces a novel practical implementation of reconfigurable intelligent surfaces (RIS) that achieve highly efficient beamforming, significantly surpassing the limitations of the conventional diagonal phase shift approach. We expand the theoretical and optimization framework based on the discrete impedance model to accommodate practical design scenarios. We validate our approach by fabricating an RIS prototype and conducting experimental measurements using the parallel plate waveguide technique. The experimental results confirm the superior performance of our approach, demonstrating at least a 30% improvement in efficiency over diagonal matrix methods, thereby enhancing signal quality and coverage. This ensures seamless communication and ubiquitous connectivity, improving the quality of service by boosting the received signal.