Abstract: An antenna device includes a radiation part and a circuit board. The radiation part includes first to third sidewalls, an extension part and a protrusion part. The second and third sidewalls are connected to the first sidewall and opposite to each other. The extension part extends toward the third sidewall from the second sidewall. The protrusion part extends toward the first sidewall from the extension part. The circuit board includes a ground layer, a feed point, a clearance area, first metal and second metal sheets. The feed point is electrically connected to the radiation part. The clearance area is in a containing space formed by the first to third sidewalls. The first metal sheet is in the clearance area and extends from the ground layer. The second metal sheet is in the clearance area, connected to the first metal sheet and the protrusion part, and parallel to the extension part.

Abstract: An antenna device includes a radiation part and a circuit board. The radiation part includes first to third sidewalls, an extension part and a protrusion part. The second and third sidewalls are connected to the first sidewall and opposite to each other. The extension part extends toward the third sidewall from the second sidewall. The protrusion part extends toward the first sidewall from the extension part. The circuit board includes a ground layer, a feed point, a clearance area, first metal and second metal sheets. The feed point is electrically connected to the radiation part. The clearance area is in a containing space formed by the first to third sidewalls. The first metal sheet is in the clearance area and extends from the ground layer. The second metal sheet is in the clearance area, connected to the first metal sheet and the protrusion part, and parallel to the extension part.

Abstract: An antenna device and a communication device using the same are provided. The communication device includes a circuit board, a first antenna and a metal plate. The circuit board has a first feed point electrically connected to a high frequency unit. The first antenna has a first radiation part electrically connected to the first feed point. The metal plate is electrically connected to ground and is configured to correspond to a shape of the projection of the first radiation part. There is a space between the metal plate and the first radiation part. The area of the metal plate is bigger than or substantially equal to the area of the projection of the first radiation part.