Oblique incidence on electromagnetic gradient surface

In recent years, a new type of electromagnetic surface, called an electromagnetic gradient surface (EGS), has been developed that is characterised by having electromagnetic gradient. Although it is geometrically flat, it reflects electromagnetic waves towards a steered angle. Unlike existing surfaces with homogeneity in reflection phase, this surface allows a reflection phase to be linear along the surface. Based on a fundamental theory of the EGS, reflection properties for oblique incidence are investigated in this work. To accurately predict the reflection properties of the surface, the wave vector approach, Huygens' approximation and a plane wave model are used with exploring phenomena of the reflected wave. For electromagnetic waves obliquely impinging on the surface, the relation between incident and reflection angles are presented and then experimentally verified.