Antenna impedance adjuster

• US 6,526,263 B1
• Filed: 08/16/1999
• Issued: 02/25/2003
• Est. Priority Date: 08/28/1998
• Status: Expired due to Term

• Current Assignee: Lenovo Innovations Ltd Hong Kong (Lenovo Group Ltd.)
• Original Assignee: NEC Corporation
• Inventors: Saito, Tetsuya
• Primary Examiner(s): Trost, William
• Assistant Examiner(s): Nguyen, Simon
• Application Number:
  US09/374,656
• Time in Patent Office: 1,289 Days
• Field of Search: 455/78, 455/83, 455/553, 455/562, 455/97, 455/107, 455/121, 455/193.1, 455/90, 343/702
• US Class Current: 455/78
• CPC Class Codes: H01Q 1/242 specially adapted for hand-held use
• CPC Class Codes: H03H 7/38 Impedance-matching networks
• CPC Class Codes: H04B 1/0458 Arrangements for matching and coupling between power amplifier and antenna or between amplifying stages matching circuits in general H03H
• 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 1/48 in circuits for connecting transmitter and receiver to a common transmission path, e.g. by energy of transmitter H04B1/46 takes precedence

Abstract

There is provided an antenna impedance adjuster including (a) an antenna through which radio signals are received and transmitted, (b) a radio signal receiver which receives radio signals having been received through the antenna, (c) a radio signal transmitter which transmits radio signals through the antenna, (d) an adjuster which matches an impedance between the antenna and the radio signal receiver in radio signal receiving band and an impedance between the antenna and the radio signal transmitter in radio signal transmitting band, (e) a first switch which electrically connects the adjuster to one of the radio signal receiver and the radio signal transmitter, and (f) a controller which controls an operation of the first switch when a radio signal is received or transmitted. The antenna impedance adjuster reduces transmission loss to be generated between an antenna and internal circuits to thereby enhance output-load characteristic in a radio signal transmitting circuit, and prevents degradation of sensitivity in a radio signal receiving circuit.

Claims

1. An antenna impedance adjuster comprising:

(a) an antenna through which radio signals are received and transmitted;

(b) a radio signal receiver which receives radio signals having been received through said antenna;

(c) a radio signal transmitter which transmits radio signals through said antenna;

(d) an adjuster which matches an impedance between said antenna and said radio signal receiver in radio signal receiving band and an impedance between said antenna and said radio signal transmitter in radio signal transmitting band, wherein said adjuster is designed to have a variable circuit structure;

(e) a first switch which electrically connects said adjuster to one of said radio signal receiver and said radio signal transmitter; and

(f) a controller which controls an operation of said first switch when a radio signal is received or transmitted,

whereby a circuit structure of said adjuster is varied when a radio signal is received or transmitted; and

wherein said adjuster includes;

(d1) a first adjuster which matches an impedance between said antenna and said radio signal receiver in radio signal receiving band;

(d2) a second adjuster which matches an impedance between said antenna and said radio signal transmitter in radio signal transmitting band, when electrically connected to said first adjuster; and

(d3) a second switch which disconnects said second adjuster from said first adjuster when a radio signal is to be received, and electrically connects said second adjuster to said first adjuster when a radio signal is to be transmitted.

2. The antenna impedance adjuster as set forth in claim 1, wherein said controller transmits a control signal to said second switch, and said second switch makes its operation in accordance with said control signal.

3. The antenna impedance adjuster as set forth in claim 1, wherein said first adjuster is comprised of:

(d11) an inductance electrically connected in series to said antenna through one end thereof, and electrically connected to said second switch through the other end thereof; and

(d12) a first capacitor electrically connected to said other end of said inductance at one end thereof, and grounded at the other end thereof,

said second adjuster is comprised of a second capacitor electrically connected at one end thereof to a point at which said first capacitor is connected to said inductance, and grounded at the other end thereof, and

said second switch is comprised of a switching device which turns said second capacitor off when a radio signal is to be received, and turns said second capacitor on when a radio signal is to be transmitted.

4. The antenna impedance adjuster as set forth in claim 3, wherein said controller transmits a control signal to said second switch, and said second switch makes its operation in accordance with said control signal.

5. The antenna impedance adjuster as set forth in claim 3, further comprising an on-off controller for controlling said switching device to turn on or off in accordance with a control signal transmitted from said controller.

6. The antenna impedance adjuster as set forth in claim 1, wherein said first adjuster is comprised of:

(d11) a first inductance electrically connected in series to said antenna through one end thereof, and electrically connected to said second switch through the other end thereof; and

(d12) a first capacitor electrically connected to said other end of said inductance at one end thereof, and grounded at the other end thereof,

said second adjuster is comprised of a second inductance electrically connected at one end thereof to a point at which said first capacitor is connected to

said first inductance, and grounded at the other end thereof, and said second switch is comprised of a switching device which turns said second inductance off when a radio signal is to be received, and turns said second inductance on when a radio signal is to be transmitted.

7. The antenna impedance adjuster as set forth in claim 6, wherein said controller transmits a control signal to said second switch, and said second switch makes its operation in accordance with said control signal.

8. The antenna impedance adjuster as set forth in claim 6, further comprising an on-off controller for controlling said switching device to turn on or off in accordance with a control signal transmitted from said controller.

9. The antenna impedance adjuster as set forth in claim 6, wherein said first adjuster is comprised of:

(d11) a first inductance electrically connected in series to said antenna through one end thereof, and electrically connected to said second switch through the other end thereof; and

(d12) a second inductance electrically connected to said other end of said first inductance at one end thereof, and grounded at the other end thereof,

said second adjuster is comprised of a third inductance electrically connected at one end thereof to a point at which said first inductance is connected to said second inductance, and grounded at the other end thereof, and

said second switch is comprised of a switching device which turns said third inductance off when a radio signal is to be received, and turns said third inductance on when a radio signal is to be transmitted.

10. The antenna impedance adjuster as set forth in claim 9, wherein said controller transmits a control signal to said second switch, and said second switch makes its operation in accordance with said control signal.

11. The antenna impedance adjuster as set forth in claim 9, further comprising an on-off controller for controlling said switching device to turn on or off in accordance with a control signal transmitted from said controller.

12. The antenna impedance adjuster as set forth in claim 1, wherein said first adjuster is comprised of:

(d11) a first inductance electrically connected in series to said antenna through one end thereof, and electrically connected to said second switch through the other end thereof;

(d12) a second inductance electrically connected to said other end of said first inductance at one end thereof, and electrically connected to a later mentioned third inductance at the other end thereof; and

(d13) a third inductance electrically connected to said second inductance at one end thereof, and grounded at the other end thereof, said second switch is comprised of a switching device which short-circuits said third inductance to a ground when a radio signal is to be transmitted.

13. The antenna impedance adjuster as set forth in claim 12, wherein said controller transmits a control signal to said second switch, and said second switch makes its operation in accordance with said control signal.

14. The antenna impedance adjuster as set forth in claim 12, further comprising an on-off controller for controlling said switching device to turn on or off in accordance with a control signal transmitted from said controller.

15. The antenna impedance adjuster as set forth in claim 1, wherein said second switch is a GaAs semiconductor element switch.