A High Gain Switchable Beam Reflectarray Antenna for Sub-6 GHz MIMO Applications

In this paper, the design of a high gain switchable beam reflectarray antenna for 5.8 GHz MIMO applications is presented. A three-port microstrip patch MIMO antenna which operates at a center frequency of 5.8 GHz, is used to excite the reflectarray surface for switching the radiation beam in the xz-plane. The unit cells of the reflectarray have an overall volume of 0.49λ x 0.49λ x 0.13λ (λ is the wavelength at a frequency of 5.8 GHz). The reflectarray consists of 19 x 19 1-bit phase quantized unit cells. The switchable beam reflectarray has a focal to dimension ratio of 0.23. The feed antenna elements have a center-to-center distance of λ/2 between each other, and mutual coupling of less than 22 dB is obtained at 5.8 GHz. The reflectarray antenna can tilt the beam in ±5° along the x direction. The antenna shows gain of 18.2dB in port-1 with a scanning loss of 0.5dB in the two offset radiation beams. The radiation beams in the xz-plane have a half power beamwidth of 5°. The antenna can be used in sub-6 GHz radar systems and cellular and satellite communications. The antenna prototype is fabricated, and performance parameters are measured.