Wide-angle-insensitive reflective 1-bit metasurface for multi-functional polarization conversion

Although polarisation conversion is widely studied, its combination with 1-bit coding metasurfaces is still underexplored, especially for wide-angle robustness, multi-frequency, multi-polarisation incidence, and angular reciprocity. This paper proposes an angle-insensitive 1-bit coding metasurface that realises multi-frequency, multi-functional polarisation conversion. It maintains stable 1-bit responses under 0°-60° oblique X/Y-polarised incidence. At the 5.8 GHz WLAN band, reflected right-hand circularly polarised (RHCP) and left-hand circularly polarised (LHCP) waves exhibit an accurate 180° phase difference with reflection loss below 0.39 dB. Its 8×8 finite array supports flexible wavefront shaping within 45° elevation. Dual-channel polarisation conversion is also observed under circular-polarised incidence with low losses and satisfactory gains, including a 1-bit co-polarised reflection band covering 5.56-5.67 GHz and the cross-polarised reflection band spanning 6.29-6.50 GHz, yielding maximum reflection losses below 1.2 dB, with realised gains exceeding 6.23 dBi and 8.41 dBi, respectively. It shows promising prospects in cloaking, diffuse reflection and secure communication.