A new pattern reconfigurable 2×2 array antenna is proposed. The antenna has two modes of operation, Array Mode and Multiple-Input-Multiple-Output (MIMO) Mode. The single element antenna used is a pattern reconfigurable U-slot antenna with four pattern configurations. An average efficiency of 80%, a peak gain of 9.4 dB, and an overlapped −10 dB impedance bandwidth of 200 MHz around the resonant frequency 3.65 GHz are achieved. The size of the proposed antenna is 140×140×21 mm3 , which is suitable for small cell base-stations. For the MIMO Mode, the antenna has a maximum ECC of 0.06 between the four patterns and a minimum isolation of 12.9 dB between the four ports. For the array Mode, the antenna has a peak gain of 12.5 dB, and steering angles for 0 ◦ ≤ θ ≤ 30◦ in the planes at φ = 0◦ and φ = 90◦ Pattern reconfigurability is achieved using electrical switching. The used substrate is FR-4 with a dielectric constant of Epsilon_r = 4.4, and a loss tangent of tan δ = 0.02.