Communication card and communication device

• US 20030144031A1
• Filed: 10/22/2002
• Published: 07/31/2003
• Est. Priority Date: 02/26/2001
• Status: Active Grant

• 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
• Granted Patent: US 7,043,269 B2
• Time in Patent Office: Days
• 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

This communication card or communication device includes: an antenna 101 for transmitting/receiving communication waves; a variable matching unit 102a which can vary a circuit parameter; a directional coupling unit 103 for extracting a reflected signal from the antenna 101; a detection unit 110 for extracting the amplitude of the reflected signal; a control unit 109 for outputting a control signal; an amplifier 104 for amplifying a high frequency signal at a RF band; a frequency converter 105 for converting an IF band signal into a RF band signal or a RF band signal into an IF band signal; a modulator/demodulator 106 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 107 for processing the baseband signal; and a card interface 108 for exchanging data with an information device. This communication card or communication device has a miniaturized part that protrudes from the body of the communication device as well as prevents deterioration of the antenna characteristics, and further makes the antenna portion hardly broken.

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 for receiving or outputting communication waves; and

an antenna matching means for establishing a conjugate match between an input impedance of the antenna and an output impedance of a matching circuit so as to have resistors 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 varying a circuit parameter as well as detecting a reflected signal from the antenna at transmission, and deciding the circuit parameter such that the reflected signal has a minimum amplitude at receiving.

2. The communication card of claim 1 wherein

the antenna matching means includes:

a variable matching unit which can vary the circuit parameter in accordance with a control signal;

a directional coupling unit for extracting the reflected signal from the antenna;

a detection unit for detecting the amplitude of the reflected signal that is extracted by the directional coupling unit; and

a control unit for outputting the control signal to the variable matching unit on the basis of the amplitude of the reflected signal that is detected by the detection unit.

3. The communication card of claim 2 wherein

the directional coupling unit includes:

two microstrip lines each having a length corresponding to a ¼

wavelength;

two coupling resistors; and

one end resistor, and

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

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

4. The communication card of claim 2 wherein

the variable matching unit includes:

plural capacitors and coils;

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

a first switch selector for controlling the first switches.

5. The communication card of claim 2 wherein

the 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 the first switches.

6. The communication card of claim 5 wherein

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

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

7. The communication card of claim 2 wherein

the control unit carries out:

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

a second step of deciding the circuit parameter of the 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.

8. The communication card of claim 7 wherein

in the second step,

one of a matching executing routine for executing matching of the antenna, and a matching monitoring routine for monitoring matching of the 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 the 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.

9. The communication card of claim 2 wherein

the variable matching unit includes:

one microstrip line;

two varactor diodes;

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

two capacitors;

two coils; and

two resistors.

10. The communication card of claim 9 wherein

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

the resistors and the variable power supplies are connected in series between connections of the coils and the varactor diodes which are connected in series, and grounding conductors, respectively.

11. The communication card of claim 2 wherein

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

12. The communication card of claim 11 wherein

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

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

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

13. The communication card of claim 12 wherein

the 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 the voltage variable phase shifter.

14. The communication card of claim 11 wherein

the variable phase shifter includes:

one hybrid coupler that uses a microstrip line; and

two varactor diodes.

15. The communication card of claim 1 wherein

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

a selectively switching means for selecting one of the plural antennas.

16. The communication card of claim 15 including:

an antenna switch as the selectively switching means.

17. The communication card of claim 15 wherein

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

18. The communication card of claim 15 wherein

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

19. The communication card of claim 15 wherein

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

20. The communication card of claim 15 wherein

the plural antennas having different polarized waves includes:

lines of a printed board;

a folded conductor plate; and

a PIN diode switch.

21. The communication card of claim 15 wherein

the 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.

22. The communication card of any of claims 15, 16, and 21 wherein

the 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 the waveguide antenna, and

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

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

23. The communication card of claim 15 wherein

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

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

24. The communication card of claim 15 wherein

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

25. 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 the antenna and an output impedance of a matching circuit so as to have resistors which are equal to each other and reactances which have opposite sings 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 varying a circuit parameter as well as detecting a reflected signal from the antenna at transmission, and deciding the circuit parameter such that the reflected signal has a minimum amplitude at the receiving.