**Abstract**

A millimeter-wave (mmW) interferometric phase transmitarray for the multiple-input multiple-output (MIMO) system is proposed, and its phase distribution is the interference superposition of electromagnetic waves radiated by two patch antennas at different locations. Its characteristic is that when multiple EM waves illuminate the center of the array, the transmitted waves are formed into highdirectivity beams. In addition, when the plane wave illuminates the interference phase transmitarray vertically, the transmissive plane wave will be scattered and focused to two different positions. A novel MIMO system can be implemented based on the above two characteristics. Compared with the conventional lens MIMO, the advantage of the MIMO system integrated by the interferometric phase transmitarray is that multiple antennas can share one transmitarray, which is beneficial to the miniaturization of the MIMO transceiver. More critically, all channels can efficiently transmit information and increase channel capacity.

**Keywords:** interferometric phase, transmitarray, MIMO, miniaturization, channel capacity
