Design of QR-coded metasurfaces for RCS reduction at mmWave

This article presents the design of 1-bit metasurfaces for radar cross section (RCS) reduction over wide frequency band from 60 GHz to 120 GHz. The proposed 1-bit metasurfaces can be designed without the need for any complicated optimization algorithms such as genetic algorithms (GA) or particle swarm algorithms (PSO), or time-consuming simulations to achieve the optimized phase distribution map. The phase distribution maps required for more than 10-dB RCS reduction of the proposed metasurfaces were generated using two-dimensional (2D) quick response (QR) 1-bit generator in MATLAB which are fast and efficient. After we carefully studied several metasurfaces with various 2D QR codes, it was found that the QR coded metasurfaces are very powerful in achieving more than 10-dB RCS reduction with low-level diffusive scattering patterns. Two metasurfaces with their unit cells phase distributions being exactly the same as the QR codes of the words “IEEE” and “Metasurface” were designed and their RCS reduction characteristics were investigated. For off-normal or oblique incidence, more than 10-dB RCS reduction is preserved up to incident angles of 60° over the entire frequency band. The simulation and measured results show the proposed QR coded metasurfaces reduce the backscattered energies and RCS by more than 10-dB for different polarizations over the frequency range from 60 GHz to 120 GHz yielding a fractional bandwidth of 66.7%. The proposed approach is powerful and fast and makes the realization of coding metasurface much easier.