Abstract: A communication device is provided. The communication device comprises a metal back cover electrically connected to a system ground plane; a first antenna unit for generating a first operating frequency band of the communication device; a second antenna unit for generating a second operating frequency band of the communication device. The first antenna unit includes a first signal source electrically connected to a first metal frame via a first matching circuit. The second antenna unit includes a second signal source electrically connected to a second metal frame via a second matching circuit. The first matching circuit and the second matching circuit are configured to adjust bandwidths and frequency ratios of the first operating frequency band and the second operating frequency band.

Abstract: A communication device is provided. The communication device comprises a metal back cover electrically connected to a system ground plane; a first antenna unit for generating a first operating frequency band of the communication device; a second antenna unit for generating a second operating frequency band of the communication device. The first antenna unit includes a first signal source electrically connected to a first metal frame via a first matching circuit. The second antenna unit includes a second signal source electrically connected to a second metal frame via a second matching circuit. The first matching circuit and the second matching circuit are configured to adjust bandwidths and frequency ratios of the first operating frequency band and the second operating frequency band.

Abstract: A communication device including a ground element and an antenna element is provided. The antenna element is adjacent to an edge of the ground element. The antenna element has a projection on the edge of the ground element. The antenna element includes a radiation element, a feeding element, and a shorting element. The radiation element has a first end and a second end, and the second end is open. The radiation element has plural bends such that the second end is adjacent to the first end. One end of the feeding element is coupled through a capacitive element to a connection point on the radiation element, and the connection point is adjacent to or at the first end. Another end of the feeding element is coupled to a signal source. The feeding element includes a first segment which is substantially parallel to the edge of the ground element.

Abstract: A communication device including a ground element and an antenna element is provided. The antenna element is adjacent to an edge of the ground element. The antenna element has a projection on the edge of the ground element. The antenna element includes a radiation element, a feeding element, and a shorting element. The radiation element has a first end and a second end, and the second end is open. The radiation element has plural bends such that the second end is adjacent to the first end. One end of the feeding element is coupled through a capacitive element to a connection point on the radiation element, and the connection point is adjacent to or at the first end. Another end of the feeding element is coupled to a signal source. The feeding element includes a first segment which is substantially parallel to the edge of the ground element.

Abstract: A communication device including a first conductive plate and an antenna system is provided. The antenna system includes a first antenna, a second antenna, a ground plane, and an open slot. Both the first antenna and the second antenna operate in at least a first band and a second band. The ground plane substantially has an inverted-T shape, and includes a main ground plane and a protruded ground plane. The main ground plane is coupled to the first conductive plate. The protruded ground plane is substantially located between the first antenna and the second antenna. The open slot is formed on the ground plane, and an open end of the open slot is located at an edge of the protruded ground plane. The open slot increases the isolation between the first antenna and the second antenna in the first band and the second band.