Various embodiments relate to an apparatus. The apparatus may include: a first printed circuit board including a first ground layer having one or more openings formed therein and a wiring layer on which a signal wire is disposed; a second printed circuit board including a second ground layer having one or more openings formed therein; a first area and a third area in which the first printed circuit board and the second printed circuit board are connected to each other via an insulating layer; and a second area, which extends from the first area to the third area, and in which the first printed circuit board and the second printed circuit board are spaced apart from each other, with an air layer interposed therebetween. Various other embodiments may be possible.