An Ultra-Wide-Angle Mechanically Steered Reflectarray Antenna (RA) Based on Non-Specular Reflection

This paper presents a non-specular reflection-based mechanically steered reflectarray antenna (RA) that achieves ultra-wide beam steering up to 80° while preserving mainlobe integrity. Conventional mechanically steered RAs are fundamentally constrained by specular reflection, where the reflection angle follows the incident angle symmetrically. Consequently, large scan angles inherently require extreme incident angles, which exacerbate aperture projection loss, element angular instability, and beam distortion. To overcome this limitation, an asymmetric reflection phase distribution is engineered to decouple the reflection angle from the incident angle, thereby relaxing the incident angle requirement for wide-angle beam steering. By mitigating extreme angular excitation of the unit cells, the proposed approach enhances angular stability and improves beam robustness at large scan angles. Full-wave simulation and measurement demonstrate stable radiation patterns without mainlobe splitting up to a scan angle of 80°. Although a gain reduction of approximately 6 dB is observed at the maximum steering angle due to intrinsic aperture projection effects, the mainlobe characteristics remain well preserved. The proposed approach provides a physically grounded and practical pathway toward ultra-wide-angle beam steering in mechanically steered RAs.