Wireless communication terminal and antenna switching control method

• US 20050245207A1
• Filed: 04/29/2005
• Published: 11/03/2005
• Est. Priority Date: 04/30/2004
• Status: Active Grant

• Current Assignee: Kyocera Corporation
• Original Assignee: Kyocera Corporation
• Inventors: Watanabe, Kunihiko, Suzuki, Tadashige
• Granted Patent: US 8,014,817 B2
• Time in Patent Office: Days
• US Class Current: 455/101
• CPC Class Codes: H04B 1/18 Input circuits, e.g. for coupling to an antenna or a transmission line coupling networks between antennas or lines and receivers independent of the nature of the receiver H03H
• CPC Class Codes: H04B 7/0871 using different reception schemes, at least one of them being a diversity reception scheme

Abstract

A wireless communication terminal able to change a resonance frequency of a sub antenna, able to reduce interference to a main antenna, and able to suppress deterioration performance in a dual terminal compatible with a plurality of transmission systems, wherein, in a wireless communication unit, at the time of a CDMA2000 1xEVDO mode, a first receiver circuit, a second receiver circuit, and a transmitter circuit are in an operative state, and, in the second receiver circuit, an input impedance is held at the 50 ohm input impedance of a LNA by an impedance control unit, while at the time of a CDMA2000 1x mode, the first receiver circuit and the transmitter circuit are in the operative state, the second receiver circuit is in an inoperative state, and, in the second receiver circuit, the input impedance is controlled so as to be shifted from the 50 ohm input impedance of the LNA by the impedance control unit, and an antenna switching control method for the same.

Claims

1. A wireless communication terminal able to selectively communicate by a first transmission system without use of a diversity method and a second transmission system with use of a diversity method and having a reception function of a frequency band where the frequency bands of the transmission systems interfere with each other, comprising:

a main antenna,

a sub antenna, and

a signal processing unit,

wherein the signal processing unit communicates by only the main antenna when the first transmission system is used for communication and combines the signals received by the main antenna and sub antenna when the second transmission system is used for communication and

makes an impedance from a reception unit to the sub antenna a first impedance able to be matched with in the frequency band used when the second transmission system is used for communication and changes the impedance to a value different from the first impedance when the first transmission system is used for communication.

2. A wireless communication terminal as set forth in claim 1, further comprising a transmission unit for transmission by the first transmission system between the main antenna and the signal processing unit.

3. A wireless communication terminal as set forth in claim 1, wherein

the terminal comprises a switch between the sub antenna and the reception unit, and

the signal processing unit separates the sub antenna from the reception unit by the switch when the first transmission system is used for communication.

4. A wireless communication terminal as set forth in claim 1, wherein the signal processing unit changes the impedance of the sub antenna to a value different from the first impedance even in a standby state.

5. A wireless communication terminal as set forth in claim 1, the signal processing unit specifies a reception slot or a non-reception slot of its own terminal at the time of reception along with the second transmission system by communication with the base station, and, even during communication by the second transmission system, changes the impedance of the sub antenna to a value different from the first impedance in a non-reception slot.

6. An antenna switching control method of a wireless communication terminal having a main antenna and a sub antenna, able to selectively communicate by a first transmission system without use of a diversity method and a second transmission system with use of a diversity method, and having a reception function of a frequency band where the frequency bands in the transmission systems interfere with each other, comprising the steps of:

communicating by only the main antenna when the first transmission system is used for communication and combining signals received by the main antenna and sub antenna when the second transmission system is used for communication and

making an impedance from a receiving means to the sub antenna a first impedance able to be matched with in a frequency band used when the second transmission system is used for communication and changing the impedance to a value different from the first impedance when the first transmission system is used for communication.