This paper designs an ultra-wideband (UWB) circularly polarized antenna based on Angle of Arrival (AOA) positioning technology. The antenna element adopts a rectangular dual-feed microstrip patch structure, and realizes right-hand circular polarization (RHCP) radiation through a 90° feeding network, which effectively suppresses vehicle multipath interference and polarization mismatch problems; a compact L-shaped three-antenna array is built based on the elements, and the array layout and feeding network are optimized to ensure phase and amplitude consistency. The simulation analysis results show that the operating frequency band of the antenna element can completely cover 6.24~8.24 GHz, with a return loss of ≤ -10 dB and an axial ratio of ≤ 3.0 dB within this band; the isolation between ports is ≤ -21dB, the gain is stable at 3.55–5.05 dBi, and the AOA positioning error is ≤ 1.4° (positioning distance 0.5–5 m). The overall size is controlled at 42mm × 30mm × 2mm, which fully meets the application requirements of automotive digital keys for miniaturization, high precision, and anti-interference. It can be directly integrated into digital key terminals, improving the reliability of contactless unlocking and the security of anti-theft authentication.