A Compact Antenna Test Range Based on a 4-bit Polarization Conversion Metasurface in Millimeter Wave Regime

In this paper, we propose a low-profile, transmissive, linearly polarized, 4-bit metasurface operating at 195 GHz. The meta-atom of the metasurface consists of three metal layers: a resonant ring aperture in the middle layer and metal grid arrays on the top and bottom layers, interconnected by dielectric substrates. By adjusting the inner diameter, ring width, and ring aperture angle, we generate sixteen meta-atoms with transmission coefficients exceeding 0.84 and a phase shift of 360°. Furthermore, a phase compensation array is designed based on the phase distribution provided by the actual feeding source, achieving a quiet zone (QZ) with ±1 dB amplitude variation and ±10° phase variation, as demonstrated through extensive simulations.