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: An antenna system includes: a plurality of antennas; a switching unit, having a plurality of switches, wherein each of the plurality of switches and the corresponding antenna are in a conducting state or in a non-conducting state; a communication unit, connected with each of the plurality of switches of the switching unit, and coupled with the antennas, wherein the communication unit receives a reference value group of the corresponding antenna from the switch in the conducting state; and a control unit, connected with the switching unit and the communication unit, wherein the control unit receives the reference value group from the communication unit, and compares the reference value group with an threshold, to determine whether the reference value group conforms to a pre-determined condition or not, and outputs a restarting instruction to restart the switching unit when the reference value group does not satisfy the pre-determined condition.

Abstract: An antenna system includes: a plurality of antennas; a switching unit, having a plurality of switches, wherein each of the plurality of switches and the corresponding antenna are in a conducting state or in a non-conducting state; a communication unit, connected with each of the plurality of switches of the switching unit, and coupled with the antennas, wherein the communication unit receives a reference value group of the corresponding antenna from the switch in the conducting state; and a control unit, connected with the switching unit and the communication unit, wherein the control unit receives the reference value group from the communication unit, and compares the reference value group with an threshold, to determine whether the reference value group conforms to a pre-determined condition or not, and outputs a restarting instruction to restart the switching unit when the reference value group does not satisfy the pre-determined condition.

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 includes a metal element. The metal element is disposed adjacent to an edge of the ground element. The metal element has a first connection point and a second connection point. A feeding point of the antenna element is coupled through an inductive element to the first connection point. A first feeding path is formed from the feeding point through the inductive element to the first connection point. The feeding point of the antenna element is further coupled through a capacitive element to the second connection point. A second feeding path is formed from the feeding point through the capacitive element to the second connection point. The feeding point of the antenna element is further coupled through a matching circuit to a signal source.

Abstract: A communication device including a ground element and an antenna element is provided. The antenna element includes a metal element. The metal element is disposed adjacent to an edge of the ground element. The metal element has a first connection point and a second connection point. A feeding point of the antenna element is coupled through an inductive element to the first connection point. A first feeding path is formed from the feeding point through the inductive element to the first connection point. The feeding point of the antenna element is further coupled through a capacitive element to the second connection point. A second feeding path is formed from the feeding point through the capacitive element to the second connection point. The feeding point of the antenna element is further coupled through a matching circuit to a signal source.