Design of Non-Uniform Metasurface-Based Phased-Array Antenna for Grating Lobes Mitigation

Grating lobes pose significant limitations to antenna array directivity and radiation efficiency, affecting the performance of wireless communication systems. This paper introduces a novel 2 × 2 phased microstrip patch antenna array integrated with a non-uniform metasurface acting as a Partially Reflective Surface (PRS) for grating lobe suppression. The non-uniform metasurface, composed of 11 × 11 unit cells, is placed above the array to form a Fabry–Perot Cavity (FPC), enabling constructive interference in the main beam direction and attenuation of undesired lobes. The non-uniform metasurface design, inspired by current-density tapering, offers a novel approach to grating-lobe problems. With an element spacing of 1.04 at 12.5 GHz, rigorous design optimization shows Grating Lobe Levels (GLLs) of -20.22 dB and peak gain increases from 10.3 dB to 19.1 dB, highlighting the design's effectiveness. This design offers a simple, low-profile solution for 5G base stations, radar, and satellite applications.