Design of multi-beam reflectarray using mushroom-like structure

Improving the propagation environment using a reflectarray has recently been proposed to eliminate blind zones or to improve the capacity of line of sight (LOS) multi-input and multi-output (MIMO) technology, which is a more significant factor at higher frequencies. For this purpose, the reflectarray must be able to scatter an arbitrary oblique incident wave (θi, φi) in an arbitrary oblique direction (θr, φr) in order to establish the reflectarray within a limited space outdoors. Moreover, a Fresnel zone multi-beam reflectarray is desired to achieve a large coverage area and high received level. This paper utilizes the fact that multiple in-phase surfaces are generated when a periodic mushroom structure is employed and proposes a novel multi-beam reflectarray using this characteristic. The design method is described and simulation and measured results are presented.