Shape‐Adaptive Flexible 3D Air‐Gap Phased‐Array Antennas via Mechanically Guided Assembly

ABSTRACT 3D architectures in flexible electronics provide an effective route to decouple mechanical compliance from functional performance, which is particularly important for shape‐adaptive radio‐frequency systems on curved platforms. However, flexible radio‐frequency devices remain susceptible to deformation‐induced variations in resonant frequency, impedance matching, and radiation efficiency. Here, we present a mechanically guided assembly strategy for flexible 3D air‐gap phased arrays that integrates conformal adaptability with deformation‐stable electromagnetic performance. Buckling‐guided assembly and a shape‐locking scheme form freestanding 3D air‐gap patch antennas on multilayer flexible printed circuit boards through vertical interconnection, providing strain‐isolated radiators with locally tunable stiffness. The air‐gap dielectric reduces dielectric loading and loss, while the out‐of‐plane geometry helps preserve radiator planarity and mitigate deformation‐induced variations in resonant frequency and impedance matching. The resulting antenna elements exhibit stable impedance characteristics under different bending directions and curvatures, with good agreement between full‐wave simulations and measurements. At the array level, integrated inertial measurement units enable shape reconstruction of the deformed aperture, and phase compensation recovers planar‐like beamforming under convex, concave, and hyperbolic deformations. This mechanically and electromagnetically co‐designed architecture provides a potential route toward lightweight, conformal, and shape‐adaptive flexible phased arrays for future wireless systems.