An electronic device may reduce influence of the housing formed of a dielectric substance upon radiating a millimeter wave signal. For example, the electronic device may allow a radiation pattern of the millimeter wave signal to have directivity in a target direction and may reduce distortion of the radiation pattern due to the housing, thereby improving the communication performance of electronic device.

According to an embodiment, an electronic device may include a housing including a front surface, a rear surface facing away from the front surface, and a side member surrounding a space between the front surface and the rear surface, a rigid printed circuit board disposed inside the housing and including a first ground, a flexible printed circuit board including a second ground and extended toward the side surface from one end of the rigid printed circuit board, a plurality of antenna elements mounted on the flexible printed circuit board and radiating a millimeter wave signal, a support member fixing the flexible printed circuit board to be at a predetermined angle with the rear surface, and a communication circuit electrically connected to the plurality of antenna elements and communicating using the millimeter wave signal. The first ground and the second ground may allow a radiation pattern of the millimeter wave signal to have directivity in a direction of the side surface, by shielding a component, which is radiated toward at least part of the front surface or the rear surface, of a millimeter wave signal radiated from the plurality of radiators. The front surface may be formed of a dielectric substance having first permittivity and the rear surface is formed of a dielectric substance having second permittivity.

According to an embodiment, the plurality of antenna elements may be spaced at a specified interval and mounted on the flexible printed circuit board.