An internal antenna for attaching to a terminal housing is disclosed. The antenna includes: a perpendicular structure formed in a perpendicular direction to a substrate and positioned in contact with an inner wall of a housing; a first conductive member electrically connected to a power feed and joined to the perpendicular structure to extend in a perpendicular direction to the substrate; and a second conductive member electrically connected to a ground, joined to the perpendicular structure, and separated by a particular distance from the first conductive member to extend in a perpendicular direction to the substrate. The first conductive member is joined to the inner wall of the housing to extend in a first direction orthogonal to the perpendicular direction, and the second conductive member is joined to the inner wall of the housing to extend in the first direction at a particular distance from the first conductive member.