An electronic device is provided. The electronic device includes a housing that includes a front surface, a rear surface facing away from the front surface, and a side surface surrounding a space between the front surface and the rear surface, wherein the front surface includes a dielectric substance having a first permittivity and the rear surface includes a dielectric substance having a second permittivity, an antenna array that is positioned adjacent to the side surface, radiates a millimeter wave signal, the antenna array including at least one antenna element, a communication circuit that is electrically connected with the antenna array and communicates by using the millimeter wave signal, and an electrical element that is positioned to be spaced from the antenna array by a specified distance such that a radiation pattern of the millimeter wave signal radiated from the antenna array has a directivity toward the side surface.