Abstract: The integration of UAVs' high maneuverability with the electronic beam-scanning capability of phased array antennas enables rapid target tracking, multi-task parallel processing, and stable communication in complex environments, significantly enhancing radar detection and communication performance. This paper systematically classifies the fundamental design aspects of UAV-mounted phased array antennas, encompassing element selection and array configuration, while summarizing their design principles. Addressing the unique application scenarios and constraints of UAV platforms, we focus on key technical challenges in phased array antenna design, including core technologies such as conformal antenna design, wideband and wide-angle scanning techniques, low-cost and lightweight implementations, and beamforming optimization. Finally, we discuss the application prospects and future development trends of UAV-based phased array antennas in communication and radar detection systems, aiming to provide valuable references for the design and application of such antennas.