A low-profile coding metasurface for broadband radar cross section reduction via beam diffusion and absorption

A low-profile coding metasurface based on beam diffusion and absorption is proposed, which can be applied for broadband Radar Cross section (RCS) reduction. Through inserting resistors into the polarization conversion element, the proposed unit cell can convert a portion of the electromagnetic wave to ohmic loss as well as retain polarization conversion. Subsequently, the power loss and surface current were used to explain the mechanism of absorption and polarization conversion, and the arrangement of the elements was optimized using a simulated annealing algorithm. Furthermore, both the simulated and measured results have shown that the RCS reduction is greater than 10 dB at 6.7-19.3 GHz (the relative bandwidth is 96.9%), and the metasurface still maintains great characteristics at 45 degrees incidence. Thanks to the proposed metasurface offer advantages such as fewer resistors, a wider bandwidth for RCS reduction, an ultra-thin profile (0.066 lambda L, where lambda L represents the longest wavelength), a stable incident angle, and a more uniform scattering of energy, it can be used in electromagnetic stealth for large targets.