Abstract: A communication device including a ground element and an antenna element is provided. The antenna element is disposed adjacent to an edge of the ground element, and a loop structure is formed by the antenna element and the edge of the ground element. The antenna element includes a first and a second metal portions, and a first and second switches. When the first switch is turned on and the second switch is turned off, the first metal portion, the second metal portion, a shorting metal portion and the first switch form a loop antenna with the ground element. When the second switch is turned on and the first switch is turned off, an inverted-F antenna is formed by the second metal portion.

Abstract: A communication device including a ground element and an antenna element is provided. The antenna element is disposed adjacent to an edge of the ground element, and a loop structure is formed by the antenna element and the edge of the ground element. The antenna element includes a first and a second metal portions, and a first and second switches. When the first switch is turned on and the second switch is turned off, the first metal portion, the second metal portion, a shorting metal portion and the first switch form a loop antenna with the ground element. When the second switch is turned on and the first switch is turned off, an inverted-F antenna is formed by the second metal portion.

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 at or adjacent to an edge of the ground element. The metal element is substantially perpendicular to the ground element. The metal element has a projection on the ground element, and the whole projection is in the internal of the ground element. The antenna element has a first feeding point and a second feeding point. The first and second feeding points are away from each other. The first and second feeding points are substantially positioned at two ends of the metal element, respectively. The first feeding point is coupled through a first switch and a first matching circuit to a communication module. The second feeding point is coupled through a second switch and a second matching circuit to the communication module.

Abstract: A communication device includes a ground element and an antenna element. The antenna element includes a loop metal element and a branch metal element. The loop metal element is adjacent to an edge of the ground element. The loop metal element has a feeding end and a grounding end. The grounding end is coupled to the ground element. The feeding end is coupled through a capacitive element and a first inductive element to a signal source. A closed region is enclosed by the loop metal element and the edge of the ground element. The branch metal element is coupled through a second inductive element to a connection point on the loop metal element. The connection point is at the front-half portion of the loop metal element. The front-half portion includes the feeding end. The branch metal element substantially extends along an outer periphery of the loop metal element.

Abstract: A communication device includes a ground element and an antenna element. The antenna element includes a loop metal element and a branch metal element. The loop metal element is adjacent to an edge of the ground element. The loop metal element has a feeding end and a grounding end. The grounding end is coupled to the ground element. The feeding end is coupled through a capacitive element and a first inductive element to a signal source. A closed region is enclosed by the loop metal element and the edge of the ground element. The branch metal element is coupled through a second inductive element to a connection point on the loop metal element. The connection point is at the front-half portion of the loop metal element. The front-half portion includes the feeding end. The branch metal element substantially extends along an outer periphery of the loop metal element.

Abstract: A communication device including a ground element and an antenna element is provided. The antenna element is disposed adjacent to an edge of the ground element, and a loop structure is formed by the antenna element and the edge of the ground element. The antenna element includes a first and a second metal portions. The first metal portion has a first and a second ends. The first end is a first feeding point of the antenna element and connected to a communication module through a capacitive element. The second metal portion has a third end connected to the second end through a first switch and a fourth end connected to the ground element through a shorting metal portion. The second metal portion further has a second feeding point connected to the communication module through a second switch and disposed away from the third end and close to the fourth end.

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 at or adjacent to an edge of the ground element. The metal element is substantially perpendicular to the ground element. The metal element has a projection on the ground element, and the whole projection is in the internal of the ground element. The antenna element has a first feeding point and a second feeding point. The first and second feeding points are away from each other. The first and second feeding points are substantially positioned at two ends of the metal element, respectively. The first feeding point is coupled through a first switch and a first matching circuit to a communication module. The second feeding point is coupled through a second switch and a second matching circuit to the communication module.

Abstract: A communication device including a ground element and an antenna element is provided. The antenna element includes a first portion and a second portion. The first portion has a first end and a second end. The first end is used as a first feeding point of the antenna element. The second portion has a third end and a fourth end. The third end is used as a second feeding point of the antenna element, and the fourth end is open. A first switch is coupled between the second end of the first portion and the third end of the second portion. The first switch is further coupled through the first portion and a first reactive circuit to a communication module. A second switch is coupled to the third end of the second portion. The second switch is further coupled through a second reactive circuit to the communication module.

Abstract: A communication device including a ground element and an antenna element is provided. The ground element has a first edge and a second edge, wherein the first edge is substantially perpendicular to the second edge. The antenna element is disposed adjacent to the first edge of the ground element. The ground element is coupled to a circuit module. The circuit module includes at least two reactive circuits, such that the antenna element is selectively operated in a first band or a second band. The antenna element and the ground element form an unsymmetrical dipole antenna structure. The longest current path length of the antenna element is less than 0.3 times the length of the second edge.