Dual RIS-Assisted Monostatic L-Band Radar Target Detection in NLoS Scenarios

Abstract: The use of a single Reconfigurable Intelligent Surface (RIS) to boost the signal-to-noise ratio (SNR) at the radar offers significant improvement in detecting targets, especially in non-line-of-sight (NLoS) scenarios. However, there are scenarios where no path exists between the radar and the target, even with a single RIS-assisted radar, due to other present obstacles. This paper derives an expression for SNR in target detection scenarios where dual RISs assist a monostatic radar in NLoS situations. We calculate the power received at the radar through a dual RIS configuration. We show that the SNR performance of RIS-assisted radars can improve with known locations of the radar and RISs. Our results demonstrate that the required accuracy in target localization can be achieved by controlling the number of RISs, the number of unit cells in each RIS, and properly selecting the locations of RISs to cover the desired region. The performance of dual RIS-assisted radar systems can surpass that of single RIS-assisted radar systems under favourable alignment and sufficiently large RIS sizes.