Joint Optimization of UAV Height and Antenna Configuration for UAV-Mounted Movable Antenna

Movable antennas (MAs) have emerged as a transformative technology for dynamic wireless environments, enabling channel optimization through agile element repositioning. This letter proposes a spectrum sharing system utilizing UAV-mounted MA (UMA) arrays, which synergistically combines vertical UAV mobility with horizontal MA movement to create a versatile optimization framework. Our core objective is to maximize the minimum channel gain for secondary users (SUs) while strictly constraining interference to primary users (PUs) via joint optimization of UAV height and antenna configuration. The resulting problem is inherently non-convex due to coupled variables and phase-dependent gains. To address this challenge, we develop an alternating optimization algorithm that iteratively refines each variable while fixing the others, ensuring convergence to a near-optimal solution. Numerical results demonstrate the superiority of the proposed UMA scheme and validate that vertical mobility significantly enhances beamforming flexibility, contributing 46.9% of total channel gain at the height of 15m.