An antenna module is provided to reduce the radio waves radiated toward a back lobe of the antenna module, and includes a printed circuit board (PCB) including at least one insulating layer, at least one antenna array disposed on an upper surface of the PCB, and at least one metal structure disposed on the upper surface of the PCB configured to shift a phase of radio waves radiated by the at least one antenna array and flowing along the upper surface of the PCB. The radio wave whose phase is shifted by passing through the metal structure is in a destructive interference relationship with a radio wave which is not affected by the metal structure thereby reducing the radio waves radiated toward a back lobe of the antenna module.