Anomalous Reflectors Using 2-Bit Coding Metasurfaces Under Oblique Incidence for Millimeter-Wave Applications

This paper presents the design, simulation, and experimental validation of six passive anomalous reflectors using 2-bit digital coding metasurfaces (DCMs) that can enable quasi-continuous single-beam steering for 5G n257 mm-wave applications. The design starts with a square-shaped meta-atom illuminated by a plane wave under an oblique incidence of −45°, enabling four discrete reflection phases with 90° phase increments. Each metasurface is constructed using identical meta-atoms in one direction and specific coding sequences in the orthogonal direction. Each supercell may contain equal or unequal numbers of meta-atoms per phase state, achieving anomalous reflections in the desired directions. As a demonstration, the design goals are six passive anomalous reflectors that produce six beams directed at −32°, −17°, −7°, +7°, +17°, and +32°. An expanded angular range with a minimal step size is also achieved by varying the frequency of the incident oblique beam. The full-wave simulations show good agreement with the analytical predictions. The far-field received power is measured across 27.5–29.5 GHz and compared to that of a perfect electric conductor (PEC). The measured frequency responses closely match those of the simulations, confirming the effectiveness of the proposed structures. These results are intended to facilitate a practical solution for wide-angle single-beam steering for mm-wave wireless communications with obstructed line-of-sight (LOS).