Abstract: A communication device includes a ground element, an antenna structure, a first reflector, a second reflector, a first tuning element, and a switch element. The first reflector is disposed adjacent to the antenna structure. The second reflector is disposed adjacent to the antenna structure. The second reflector is separate from the first reflector. The switch element is coupled to the first tuning element. When the switch element is enabled, the switch element couples the first tuning element to the first reflector or the second reflector. When the switch element is disabled, the first tuning element is separate from the first reflector and the second reflector.

Abstract: A communication device includes a ground element, an antenna structure, a first reflector, a second reflector, a first tuning element, and a switch element. The first reflector is disposed adjacent to the antenna structure. The second reflector is disposed adjacent to the antenna structure. The second reflector is separate from the first reflector. The switch element is coupled to the first tuning element. When the switch element is enabled, the switch element couples the first tuning element to the first reflector or the second reflector. When the switch element is disabled, the first tuning element is separate from the first reflector and the second reflector.

Abstract: An antenna system includes at least a first tunable antenna. The first tunable antenna includes a first radiation element, a second radiation element, a transmission line, and a switch circuit. The transmission line includes a first segment, a second segment, and a phase-adjustment segment. The first radiation element is coupled through the first segment to a first feeding point. The second radiation element is coupled through the second segment to a second feeding point. The switch circuit is configured to switch between the first feeding point and the second feeding point, so that the first feeding point or the second feeding point is arranged for receiving a feeding signal. The phase-adjustment segment has a first end and a second end. The first feeding point is positioned at the first end of the phase-adjustment segment. The second feeding point is positioned at the second end of the phase-adjustment segment.

Abstract: An antenna system includes at least a first tunable antenna. The first tunable antenna includes a first radiation element, a second radiation element, a transmission line, and a switch circuit. The transmission line includes a first segment, a second segment, and a phase-adjustment segment. The first radiation element is coupled through the first segment to a first feeding point. The second radiation element is coupled through the second segment to a second feeding point. The switch circuit is configured to switch between the first feeding point and the second feeding point, so that the first feeding point or the second feeding point is arranged for receiving a feeding signal. The phase-adjustment segment has a first end and a second end. The first feeding point is positioned at the first end of the phase-adjustment segment. The second feeding point is positioned at the second end of the phase-adjustment segment.