Communication card and communication device

• US 7,043,269 B2
• Filed: 02/26/2002
• Issued: 05/09/2006
• Est. Priority Date: 02/26/2001
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Kirino, Hideki, Shinabe, Munehiro, Ono, Yasushi
• Primary Examiner(s): Milord, Marceau
• Application Number:
  US10/258,168
• Publication Number:
  US 20030144031A1
• Time in Patent Office: 1,533 Days
• Field of Search: 455/41.1, 455/41.2, 455/557, 455/558, 455/556.1, 455/556.2, 455/90.1, 340/572.1, 340/572.7, 342/357.09, 342/357.1
• US Class Current: 455/558
• CPC Class Codes: H03J 2200/10 Tuning of a resonator by means of digitally controlled capacitor bank
• 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

Abstract

A communication card or communication device is provided that includes an antenna for transmitting/receiving communication waves; a variable matching unit which can vary a circuit parameter; a directional coupling unit for extracting a reflected signal from the antenna; a detection unit for extracting the amplitude of the reflected signal; a control unit for outputting a control signal; an amplifier for amplifying a high frequency signal at a RF band; a frequency converter for converting an IF band signal into a RF band signal or a RF band signal into an IF band signal; a modulator/demodulator for modulating an IF signal to obtain a baseband signal at the transmission and demodulating an IF signal to obtain a baseband signal at the receiving; a baseband processor for processing the baseband signal; and a card interface for exchanging data with an information device.

Claims

1. A communication card as a card-shaped communication device that is used being inserted into a card slot of an information device,

said communication card including:

an antenna operable to receive or output communication waves; and

an antenna matching means for establishing a conjugate match between an input impedance of said antenna and an output impedance of a matching circuit so as to have resistances which are equal to each other and reactances which have opposite signs but equal absolute values,

said antenna being placed to be electromagnetically coupled with a metallic body which constitutes the information device, via an internal wall of the card slot, and

said antenna matching means comprising;

a variable matching unit operable to vary a circuit parameter in accordance with a control signal;

a directional coupling unit operable to extract a reflected signal from said antenna;

a detection unit operable to detect an amplitude of the reflected signal that is extracted by said direction coupling unit; and

a control unit operable to output the control signal to said variable matching unit on the basis of the amplitude of the reflected signal that is detected by said detection unit.

2. The communication card of claim 1,

wherein said directional coupling unit includes:

two microstrip lines each having a length corresponding to a ¼

wavelength;

two coupling resistors; and

one end resistor,

wherein both ends of the two microstrip lines are connected with each other by the two coupling resistors, respectively, and

wherein an end of one of the two microstrip lines and a grounding conductor are connected by the end resistor.

3. The communication card of claim 1,

wherein said variable matching unit includes:

plural capacitors and coils;

first switches for making effective an arbitrary capacitor and coil among said plural capacitors and coils; and

a first switch selector for controlling said first switches.

4. The communication card of claim 1,

wherein said variable matching unit includes one microstrip line, plural capacitors, first switches for making effective an arbitrary capacitor among the plural capacitors, and a first switch selector for controlling said first switches.

5. The communication card of claim 4,

wherein said plural capacitors included in said variable matching unit are connected to said microstrip line and a grounding conductor at predetermined intervals on said microstrip line, and

wherein said microstrip line is connected between an input terminal of said antenna and an input terminal of said variable matching unit.

6. The communication card of claim 1,

wherein said control unit carries out:

a first step of extracting the reflected signal from said antenna;

a second step of deciding the circuit parameter of said variable matching unit according to the amplitude of the reflected signal that is extracted in the first step; and

a third step of generating the control signal on the basis of the circuit parameter that is decided in the second step, repeatedly in this order.

7. The communication card of claim 6, wherein

in the second step,

one of a matching executing routine for executing matching of said antenna, and a matching monitoring routine for monitoring matching of said antenna is selected, and

the selected routine is executed so that, in the matching executing routine, random circuit parameters are generated to decide a circuit parameter at which the reflected signal from said antenna is minimized, and

in the matching monitoring routine, start of the conjugate match is decided when a deterioration degree of the conjugate match exceeds a threshold from viewpoints of a level and time.

8. The communication card of claim 1,

wherein the variable matching unit includes:

one microstrip line;

two varactor diodes;

two variable voltage devices generating voltages which are to be applied to said two varactor diodes;

two capacitors;

two coils; and

two resistors.

9. The communication card of claim 8,

wherein said capacitors, said coils, and said varactor diodes are connected in series between both ends of said microstrip line included in said variable matching unit, and grounding conductors, respectively, and

said resistors and said variable voltage devices are connected in series between connections of said coils and said varactor diodes which are connected in series, and grounding conductors, respectively.

10. The communication card of claim 1,

wherein said variable matching unit includes a variable phase shifter which can vary a phase amount of a signal that passes through the shifter itself.

11. The communication card of claim 10,

wherein assuming that said variable matching unit employs two of said variable phase shifters, and one of said variable phase shifters is a first variable phase shifter and the other is a second variable phase shifter,

said first variable phase shifter is connected between an input terminal of said antenna and an input terminal of said variable matching unit, and

said second variable phase shifter is connected between said input terminal of said variable matching unit and a grounding conductor.

12. The communication card of claim 11,

wherein said variable phase shifter is a voltage variable phase shifter in which passed phase amounts vary with voltages, and

includes a variable power supply that generates a voltage that is applied to said voltage variable phase shifter.

13. The communication card of claim 10,

wherein said variable phase shifter includes:

one hybrid coupler that uses a microstrip line; and

two varactor diodes.

14. The communication card of claim 1,

wherein plural antennas having different polarized waves are included as said antenna, and

wherein a selectively switching means is provided for selecting one of said plural antennas.

15. The communication card of claim 14, further including:

an antenna switch as said selectively switching means.

16. The communication card of claim 14,

wherein said plural antennas having different polarized waves are two rectangular loop antennas which employ lines of a printed board.

17. The communication card of claim 14,

wherein said plural antennas having different polarized waves are antennas which generate two elliptical polarized waves having opposite rotations.

18. The communication card of claim 14,

wherein said plural antennas having different polarized waves are two dipole antennas which are placed orthogonally with each other.

19. The communication card of claim 14,

wherein said plural antennas having different polarized waves includes:

lines of a printed board;

a folded conductor plate; and

a PIN diode switch.

20. The communication card of claim 14,

wherein said plural antennas having different polarized waves generate three electric fields having different polarized waves by controlling electric fields which are generated by a waveguide antenna and a ½

-wavelength linear antenna.

21. The communication card of claim 14,

wherein said plural antennas having different polarized waves include:

a waveguide antenna that is constituted by lines of a printed board and a folded conductor plate; and

one linear antenna having a length corresponding to a ½

wavelength in the vicinity of an opening surface of said waveguide antenna,

wherein the linear antenna is placed so as to generate an electric field that is perpendicular to an electric field which is generated by said waveguide antenna, and

wherein an opening wall of the waveguide antenna and the linear antenna are connected via a switch.

22. The communication card of claim 14,

wherein an antenna switch button as said selectively switching means is provided on an end surface of said communication card, and

wherein one of said plural antennas having different polarized waves is selected when said switch button is pushed.

23. The communication card of claim 14,

wherein one of said plural antennas having different polarized waves is selected by software included in an information device that is capable of using said communication card.

25. The communication card of claim 15,

wherein said plural antennas having different polarized waves include:

a waveguide antenna that is constituted by lines of a printed board and a folded conductor plate; and

one linear antenna having a length corresponding to a ½

wavelength in the vicinity of an opening surface of said waveguide antenna,

wherein said linear antenna is placed so as to generate an electric field that is perpendicular to an electric field which is generated by said waveguide antenna, and

wherein an opening wall of said waveguide antenna and said linear antenna are connected via a switch.

26. The communication card of claim 20,

wherein said plural antennas having different polarized waves include:

a waveguide antenna that is constituted by lines of a printed board and a folded conductor plate; and

one linear antenna having a length corresponding to a ½

wavelength in the vicinity of an opening surface of said waveguide antenna,

wherein said linear antenna is placed so as to generate an electric field that is perpendicular to an electric field which is generated by said waveguide antenna, and

wherein an opening wall of said waveguide antenna and said linear antenna are connected via a switch.

24. An information device that is used being attached to a connector of an information device,

said information device including:

an antenna for receiving or outputting communication waves;

an antenna matching means for establishing a conjugate match between an input impedance of said antenna and an output impedance of a matching circuit so as to have resistances which are equal to each other and reactances which have opposite signs but equal absolute values,

said antenna being placed to be electromagnetically coupled with a metallic body which constitutes the information device, and

said antenna matching means comprising;

a variable matching unit operable to vary a circuit parameter in accordance with a control signal;

a directional coupling unit operable to extract a reflected signal from said antenna;

a detection unit operable to detect an amplitude of the reflected signal that is extracted by said direction coupling unit; and

a control unit operable to output the control signal to said variable matching unit on the basis of the amplitude of the reflected signal that is detected by said detection unit.