ABSTRACT To address the severe path loss degradation in the millimeter‐wave band and its consequential significant reduction in received signal‐to‐noise ratio, high‐gain antennas supporting 2‐D beam scanning are critically required. This letter proposes a sliding‐aperture 2‐D beam‐scanning transmitarray (TA) solution. The proposed TA comprises 21 × 41 unit cells, and each unit cell integrates a four‐layer metallic Jerusalem cross‐slot structure, achieving transmission amplitude within 1.3 dB and