  Conventional structural Luneburg lens is a symmetric circular gradient-index
lens with refractive indices decreasing from the centre along the radial
direction. In this paper, a flattened structural Luneburg lens (FSLL) based on
structural thickness variations is designed by using the quasi-conformal
transformation (QCT) technique. Through numerical simulations and experimental
studies, the FSLL is demonstrated to have excellent beam steering performance
for the manipulation of flexural wave propagation at desired angles.
