Wideband/Wide-Angle Planar Single-Layer Retroreflector Using Double Gradient Metasurfaces

In this paper, a new type of metasurface called Double Gradient Metasurface (DGM) is proposed, which can be used to implement a planar and low-profile retroreflector with a continuous wide incident angle range or a wide frequency width. The proposed structure consists of a set of supercells with a number of unitcells embedded into them. The design is performed based on the array factor method, taking into account the periodicity gradient of supercells and the phase gradient of unitcells. To validate the proposed method, two retroreflector prototypes with a thickness approximately equal to
$0.04\lambda _{\text {o}}$
are designed and fabricated. The first prototype is designed for a continuous wide incident angle view from 15° to 50° at 10 GHz. The second prototype is designed for a wide frequency range from 9GHz to 11 GHz at an incident angle of 20°.