WO2008010354A1

WO2008010354A1 - Wireless communication device

Info

Publication number: WO2008010354A1
Application number: PCT/JP2007/061226
Authority: WO
Inventors: Hironori Hirata; Kazunari Taki
Original assignee: Brother Kogyo Kabushiki Kaisha
Priority date: 2006-07-18
Filing date: 2007-06-01
Publication date: 2008-01-24
Also published as: JP2008028450A

Abstract

It is an object to provide a wireless communication device configured to synthesize receiving signals received by a plurality of antenna elements with the least possible loss. An antenna (18) of a wireless tag communication device (12) or the like is comprised of a plurality of antenna elements (26), cancel circuits (66) corresponding to the antenna elements (26) to suppress detouring signals from a transmitting side and contained in a receiving signals receive by the antenna elements (26), receiving amplifiers (62) for amplifying the receiving signals applied by the cancel circuits (66), and a receiving signal synthesizing unit (28) for synthesizing output signals from the receiving amplifiers (62). Since the cancel circuit (66) is provided for every antenna element (26), the receiving amplifier (62) can be provided corresponding to each antenna element (26) and a loss at the receiving signal synthesizing unit (28) can be sufficiently reduced.

Description

Specification

Wireless communication device

Technical field

TECHNICAL FIELD [0001] The present invention relates to an improvement in a wireless communication apparatus having a cancel circuit for suppressing a sneak signal from a transmission side.

Background art

There is known a radio communication device having a transmission unit that transmits a predetermined transmission signal from a transmission antenna and a reception unit that receives a reply signal returned in response to the transmission signal by a reception antenna. . For example, an RFID (Radio Frequency Identification) system RFID tag communication device (interrogator) that reads information without contact from a small RFID tag (responder) in which predetermined information is stored. This RFID system can read the information stored in the RFID tag by communicating with the RFID tag communication device even when the RFID tag is dirty or invisible. Therefore, practical use is expected in various fields such as product management and inspection processes.

[0003] By the way, normally, the wireless tag communication device transmits a predetermined transmission signal to the wireless tag.

Transmits (interrogation wave) with antenna power and communicates information with the wireless tag by receiving a response signal (response wave) returned from the wireless tag that received the transmission signal. However, there is a case where a strong sneak signal (direct wave) from the transmission side is mixed in the received reply signal and the overall received signal strength is increased. As a result, the allowable input intensity of the amplifier is exceeded, so that the received signal cannot be sufficiently amplified. As a result, the response signal component from the wireless tag cannot be sufficiently amplified. There was a problem that the gnal-to-noise ratio decreased. In view of this, a cancel circuit for removing such a sneak signal from the transmitting side has been proposed. For example, this is the carrier phase noise suppression circuit described in Patent Document 1. According to this technique, a part of the transmission signal output from the transmission system is distributed, the phase and amplitude are controlled, a cancellation signal is generated and synthesized with the reception signal, and included in the reception signal. It is said that the sneak signal of the transmission side force can be suitably removed. [0004] Patent Document 1: Japanese Patent Laid-Open No. 10-62518

Disclosure of the invention

Problems to be solved by the invention

[0005] As an example of the wireless communication apparatus, an apparatus having an array antenna having a plurality of antenna element forces and performing directivity control such as PAA (Phased Array Antenna) processing is known. In this PAA process, the reception directivity can be controlled by controlling the phase of each of the received signals received by the plurality of antenna elements and then combining (adding) the signals through a multiplexer. Here, in the conventional technique as described above, the cancellation circuit is usually provided so as to remove the sneak signal of the transmission side force included in the synthesized signal synthesized by the multiplexer. By the way, when PAA processing is performed using the array antenna, there is a problem that a loss occurs in the multiplexer that combines the received signals respectively received by the plurality of antenna elements. In order to reduce this loss, it is conceivable that an amplifier such as an LNA (Low Noise Amplifier) is provided in the receiving circuit. In the configuration in which the cancel cell circuit is provided downstream of the multiplexer, On the upstream side, the sneak signal of the transmitting side is so large that it saturates, so an amplifier cannot be provided, and the loss in the multiplexer cannot be reduced sufficiently. That is, there has been a demand for the development of a wireless communication device that can reduce as much as possible the loss in combining received signals respectively received by a plurality of antenna elements.

[0006] The present invention has been made against the background of the above circumstances, and the object of the present invention is to reduce as much as possible the loss in combining received signals respectively received by a plurality of antenna elements. It is an object of the present invention to provide a wireless communication device.

Means for solving the problem

In order to achieve such an object, the gist of the present invention is that a transmission signal is transmitted from a transmission antenna and a reply signal returned from a communication object according to the transmission signal is used for reception. A wireless communication device that receives information from an antenna and communicates information with an object to be communicated, wherein the receiving antenna has a plurality of antenna element forces, and each of the plurality of antenna elements corresponds to each of the plurality of antenna elements. Cancel signal to suppress the sneak signal from the transmission side included in the received signal received by the antenna element. A cancel circuit to be generated, and an amplifying unit that amplifies a received signal to which the cancel signal generated by the cancel circuit is applied, and a combining unit that combines output signals from the plurality of amplifying units. It is characterized by being provided.

The invention's effect

According to this configuration, the reception antenna has a plurality of antenna element forces, and corresponds to each of the plurality of antenna elements, and includes a transmission side included in a reception signal received by the antenna element. A cancel circuit for generating a cancel signal for suppressing a sneak signal from the signal, and an amplifying unit for amplifying a received signal to which the cancel signal generated by the cancel circuit is applied, and the plurality of amplifying units Since there is a multiplexing unit for synthesizing the output signals from, a cancellation circuit is provided for each of the plurality of antenna elements, so that an amplification unit is provided for each antenna element. As a result, the loss in the multiplexing portion can be sufficiently reduced. That is, it is possible to provide a wireless communication device that can reduce loss as much as possible when combining received signals respectively received by a plurality of antenna elements.

[0009] Here, preferably, a phase shift unit for controlling a phase of an output signal from the amplification unit is provided corresponding to each of the plurality of antenna elements, and the multiplexing unit includes the phase shift unit. The output signal from is synthesized. In this way, it is possible to reduce as much as possible the loss when combining the received signals respectively received by the plurality of antenna elements in the array antenna that can control the reception directivity.

[0010] Preferably, a homodyne detection circuit for demodulating a reception signal received by the reception antenna is provided. In this way, in a wireless communication device equipped with a homodyne detection circuit that is greatly affected by the sneak signal from the transmission side, the loss when combining the received signals received by the multiple antenna elements is reduced as much as possible. It can be made.

[0011] Preferably, the cancel circuit includes a plurality of sets of attenuating units and phase shift units each having different characteristics in order to generate a cancel signal for suppressing a sneak signal from the transmission side. According to the carrier frequency of the transmission signal. Either one of the set of attenuation parts and phase shift parts is selectively used. In this way, the configuration of the cancel circuit can be made as simple as possible.

[0012] Preferably, the cancel circuit changes a variable attenuator and a phase shift amount that can change an attenuation factor in order to generate a cancel signal for suppressing a sneak signal from the transmission side. The variable phase shift section is obtained, and the attenuation factor and phase shift amount in the variable attenuation section and variable phase shift section can be controlled. In this way, by appropriately controlling the attenuation rate and the amount of phase shift, it is possible to suppress the sneak signal of the transmission side force as much as possible corresponding to each antenna element.

[0013] In addition, preferably, a transmission / reception shared antenna including the plurality of antenna elements is provided, which transmits the transmission signal and receives a return signal returned from a communication target according to the transmission signal. Is. In this way, the configuration of the apparatus can be made as simple as possible.

[0014] Preferably, the transmitting antenna and the receiving antenna are individually provided. In this way, the configuration of the apparatus can be varied such that only the receiving antenna is an array antenna.

[0015] Preferably, each of the plurality of antenna elements has a distribution unit for distributing the transmission signal to each antenna element and a cancel circuit, and the distribution unit distributes the cancellation signal. The output to the circuit side is smaller than the output to the antenna element side. In this way, it is possible to reduce the amplification factor of the amplifier used when producing the transmission signal.

[0016] Preferably, the output to the cancel circuit side distributed by the distribution unit is 1Z10 or less of the output to the antenna element side. In this way, the loss in the distribution part of the transmission signal transmitted by the transmission antenna can be reduced, and the amplification factor of the amplifier used for generating the transmission signal can be reduced.

[0017] Preferably, in accordance with each of the plurality of antenna elements, an addition for adding the cancellation signal supplied by the cancellation circuit force and the reception signal received by the antenna element with a predetermined weight, respectively. And the weight of the cancel signal added in the adder is smaller than the weight of the received signal. If you do this The SN ratio in the reception process can be improved.

[0018] Preferably, the adder multiplexes and outputs a cancel signal supplied with the cancel circuit force and a received signal received by the antenna element at a predetermined ratio. The amount of transmission from the received signal input side to the output side is larger than the amount of transmission from the cancel signal input side to the output side. In this way, the loss of the received signal is reduced, while the loss of the cancel signal is relatively large. However, there is an advantage that it is not necessary to greatly attenuate.

[0019] Preferably, the weight of the cancel signal added in the adder is 1Z10 or less of the weight of the received signal. In this way, the signal-to-noise ratio in the reception process can be improved as much as possible.

[0020] Preferably, a ratio of a transmission amount from the cancel signal input side to the output side with respect to a transmission amount from the reception signal input side to the output side in the adding unit is equal to or less than lZio. In this way, the loss of the received signal is 10% or less, and the loss can be suppressed to a very small level.

[0021] Preferably, a signal strength detection unit that detects a signal strength of the received signal is provided, and the received signal strength detected by the signal strength detection unit corresponding to each of the plurality of antenna elements. A circuit switching unit that switches a circuit so that the received signal is input to the phase shift unit without passing through the amplification unit when the value is greater than or equal to a predetermined value. In this way, it is possible to suitably prevent the amplification unit from being saturated when the received signal is relatively large.

[0022] Preferably, when the received signal strength detected by the signal strength detection unit is less than a predetermined value corresponding to each of the plurality of antenna elements, the cancellation circuit generates the received signal strength. A second circuit switching unit that switches circuits so that the received signal is input to the phase shift unit without applying a cancel signal is provided. In this way, noise generation can be suitably suppressed when the received signal is relatively small and it is not necessary to apply a cancel signal.

[0023] Preferably, a second cancellation circuit for suppressing a sneak signal from the transmission side included in the output signal from the multiplexing unit is provided. This way, sending The sneak signal from the transmission side can be more suitably suppressed, and the SN ratio in the reception processing can be improved as much as possible.

[0024] Preferably, the wireless communication device transmits a predetermined transmission signal to a wireless tag that is a communication target through a transmission antenna, and responds to the transmission signal with the wireless tag power reply. The wireless tag communication device performs communication of information with the wireless tag by receiving the reply signal to be received by the receiving antenna. In this way, with regard to the RFID tag communication device that is particularly affected by the sneak signal of the transmitting side, the loss when combining the received signals respectively received by the plurality of antenna elements can be reduced as much as possible. Can do.

Brief Description of Drawings

FIG. 1 is a diagram for explaining a wireless tag communication system in which a wireless communication apparatus of the present invention is preferably used.

FIG. 2 is a diagram illustrating a configuration of a wireless tag communication device that is an embodiment of the wireless communication device of the present invention.

3 is a diagram illustrating in detail the configuration of a transmission / reception module provided in the RFID tag communication apparatus of FIG. 2.

4 is a diagram for explaining in detail the configuration of a cancel circuit provided in the transmission / reception module of FIG. 3. FIG.

FIG. 5 is a diagram showing an example of an attenuator circuit and a phase shift circuit in the cancel circuit of FIG.

FIG. 6 is a table provided for a directivity direction of 0 ° in a cancel circuit of a transmission / reception module provided corresponding to a predetermined antenna element in the RFID tag communication apparatus of FIG. 2.

7 is a tape glue provided for a directivity direction of 0 ° in a cancel circuit of a transmission / reception module provided corresponding to an antenna element different from that of FIG. 6 in the RFID tag communication apparatus of FIG.

[FIG. 8] Tape provided for a 10 ° directivity direction in the cancel circuit of the transmission / reception module provided corresponding to a predetermined antenna element in the RFID tag communication apparatus of FIG. It is le.

FIG. 9 is a table provided for a directivity direction of 10 ° in a cancel circuit of a transmission / reception module provided corresponding to an antenna element different from that of FIG. 8 in the RFID tag communication apparatus of FIG.

10 is a diagram illustrating a configuration of a wireless tag circuit element provided in a wireless tag that is a communication target of the wireless tag communication device in FIG. 2.

FIG. 11 is a diagram for explaining a difference in noise factor depending on a position where a reception amplifier is provided in a reception circuit, and a diagram illustrating a configuration without an LNA upstream from a multiplexing unit.

FIG. 12 is a diagram for explaining a difference in noise factor depending on a position where a receiving amplifier is provided in a receiving circuit, and a diagram illustrating a configuration provided with an LNA upstream from a multiplexing unit. FIG. 6 is a diagram for explaining the configuration of a wireless tag communication device that is another preferred embodiment of the wireless communication device.

14] FIG. 14 is a diagram for explaining in detail the configuration of a transmission / reception module provided in the RFID tag communication apparatus of FIG.

15 is a diagram for explaining in detail the configuration of another transmission / reception module provided in the RFID tag communication apparatus of FIG. 13.

FIG. 16 is a flowchart for explaining a main part of cancel table creation control by the wireless tag communication device of FIG.

FIG. 17 is a flowchart explaining the main part of RFID tag communication control by the RFID tag communication apparatus of FIG.

FIG. 18 is a diagram for explaining in detail the configuration of a transmission / reception module that is suitably provided in the wireless tag communication device of FIG.

[FIG. 19] A transmission / reception module equipped with a cancel circuit having a variable attenuation section capable of changing an attenuation factor and a variable phase shift section capable of changing a phase shift amount, which is preferably provided in the RFID tag communication apparatus of FIG. It is a figure explaining a structure in detail. Explanation of symbols

[0026] 10: wireless tag communication system, 12, 100: wireless tag communication device (wireless communication device), 14: wireless tag (communication object), 18: array antenna (transmitting / receiving antenna), 20: local oscillator, 22: Carrier amplifier 24, 102, 120, 130: Transmitter / receiver module 26: Antenna element 28: Received signal synthesizer (combining unit) 30: Cancel signal generator (second cancel circuit) 32: Cancel signal Synthesis unit, 34: Variable amplification unit, 36: Homodyne detection circuit, 38: AZD conversion unit, 40: Memory unit, 42: Response data interpretation unit, 44: Transmission data generation unit, 46: Cancel control unit, 48: Cancel Phase shift section, 50: Cancel amplifier, 52: Cancel attenuator, 54: Transmit phase shift section, 56: Transmit amplifier, 58: Filter, 60: Transmit / receive separation section, 62: Receive amplifier (amplifier section), 64: Receive Phase shifter, 66, 136: Cancel circuit, 68: Attenuator circuit (Attenuator) ), 70: Phase shift circuit (phase shift section), 72: Circuit switching section, 76: RFID circuit element, 78: Antenna section, 80: IC circuit section, 82: Rectifier section, 84: Power supply section, 86: Clock extraction unit, 88: Memory unit, 90: Modulation / demodulation unit, 92: Control unit, 94: Reception antenna, 96: Multiplexing unit, 98: LNA, 104: Signal strength detection unit, 106: First power bra ( (Distribution unit), 108: second force bra (addition unit), 110: first circuit switching unit, 112: second circuit switching unit, 114: third circuit switching unit, 116: fourth circuit switching unit, 11 8 : 5th circuit switching section, 122: Transmitting antenna element, 124: Transmitting filter, 126: Reception antenna element, 128: Reception filter, 132: Cancel phase shift section (variable phase shift section), 134: Cancel attest Neta (variable attenuation part)

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

Example

FIG. 1 is a diagram illustrating a radio tag communication system 10 in which the radio communication apparatus of the present invention is preferably used. The RFID tag communication system 10 includes an RFID tag communication device 12 which is an embodiment of the RFID communication device of the present invention, and one or more (single in FIG. 1) communication targets of the RFID tag communication device 12. This is a so-called RFID (Radio Frequency Identification) system composed of a wireless tag 14, wherein the wireless tag communication device 12 functions as an interrogator of the RFID system, and the wireless tag 14 functions as a responder. That is, the interrogation wave F (transmission signal) is transmitted from the wireless tag communication device 12 toward the wireless tag 14. Once trust, the question wave F is modulated in the wireless tag 14 that has received the interrogation wave F _e a predetermined command (transmission data), as a response wave F (response signal) to the radio tag communications unit 12 Information is communicated between the wireless tag communication device 12 and the wireless tag 14 by returning the response. The wireless tag communication system 10 is used, for example, for management of articles in a predetermined communication area, and the wireless tag 14 is preferably attached to an article to be managed, for example. And are provided integrally.

FIG. 2 is a diagram illustrating the configuration of the wireless tag communication device 12. As shown in FIG. 2, the RFID tag communication apparatus 12 of the present embodiment includes a local oscillator 20 that generates a predetermined local signal corresponding to a carrier wave, and a carrier wave amplification that amplifies the carrier wave output from the local oscillator 20 Unit 22 and a plurality of (three in FIG. 2) processing received signals received by the antenna element 26 and transmitted from the corresponding antenna element 26 based on the carrier wave supplied from the carrier amplifier 22 ) Transmission / reception modules 24a, 24b, 24c (hereinafter simply referred to as transmission / reception module 24 unless otherwise specified), and transmission / reception shared antenna elements 26a provided for each transmission / reception module 24a, 24b, 24c, 26b, 26c (hereinafter simply referred to as the antenna element 26 unless otherwise distinguished) and a multiplexing unit that combines (adds) the reception signals supplied from the plurality of transmission / reception modules 24. A received signal combining unit 28, a cancel signal generating unit 30 for generating a cancel signal for suppressing a sneak signal from the transmission side based on the carrier wave supplied from the local oscillator 20, and the received signal combining unit 28 A cancel signal combining unit 32 that combines (adds) the combined received signal supplied from the cancel signal generating unit 30 and the cancel signal supplied from the cancel signal generating unit 30, and a combined signal supplied from the cancel signal combining unit 32. A variable amplifying unit 34 for amplifying, a homodyne detection circuit 36 for homodyne detection of the combined signal supplied from the variable amplification unit 34, and an AZD conversion unit 38 for digitally converting the detection result output from the homodyne detection circuit 36; The memory unit 40 for storing the signal digitally converted by the AZD conversion unit 38, and the signal stored in the memory unit 40 are read out to A response data interpretation unit 42 for interpreting response data included in a response signal from the line tag 14, a transmission data generation unit 44 for generating transmission data to be carried on a carrier in the transmission / reception module 24, and the cancel signal Cancel signal generated by generator 30 And a cancel control unit 46 for controlling. In the RFID tag communication apparatus 12 of this embodiment, the antenna elements 26a, 26b, and 26c constitute an array antenna 18 that is shared for transmission and reception, and the array antenna 18 functions as a transmitting antenna and a receiving antenna. .

[0030] The cancel signal generation unit 30 includes a cancel phase shift unit 48, which is a variable phase shifter for controlling the phase of the carrier wave supplied from the local oscillator 20 as a cancel cell signal, and the cancel phase shift unit 30. The cancel amplifier 50, which is a variable gain amplifier for amplifying the cancel signal output from the unit 48, and the variable attenuation for attenuating the cancel signal output from the cancel amplifier 50 and supplying it to the cancel signal combining unit 32 A cancel attenuator 52 as a container. The cancel control unit 46 outputs a phase control signal for controlling the phase of the cancel signal generated by the cancel signal generation unit 30, and the cancel phase shift unit 48 includes the cancel control unit 48. The phase (phase shift amount) of the carrier wave is controlled according to the phase control signal supplied from 46. The cancel control unit 46 outputs an amplitude control signal for controlling the amplitude of the cancel signal generated by the cancel signal generating unit 30, and the cancel attenuator 52 controls the cancel control. The amplitude (attenuation) of the carrier wave is controlled according to the amplitude control signal supplied from the unit 46. In the wireless tag communication device 12 of the present embodiment, the cancel signal generation unit 30 is a second for suppressing the sneak signal from the transmission side included in the output signal from the reception signal synthesis unit 28. It functions as a cancel cell circuit.

FIG. 3 is a diagram for explaining the configuration of the transmission / reception module 24 in detail. As shown in FIG. 3, the transmission / reception module 24 includes a transmission phase shifter 54 that is a variable phase shifter for controlling the phase of the carrier wave supplied from the carrier wave amplification unit 22, and its transmission phase shift. 54 A transmission amplifier 56 that is a variable gain amplifier for modulating the output carrier wave with predetermined transmission data and outputting the transmission signal, and a signal transmission path between the transmission amplifier 56 and the antenna element 26 And a transmission signal output from the transmission amplifier 56 is supplied to the antenna element 26 through the filter 58, and is received by the antenna element 26 and supplied through the filter 58. Received signal The transmission / reception separation unit 60 supplied to the reception amplifier 62, the reception amplifier 62 which is a variable gain amplifier for amplifying the reception signal supplied from the transmission / reception separation unit 60, and the reception signal output from the reception amplifier 62 A reception phase shifter 64, which is a variable phase shifter for controlling the phase, a signal transmission path between the transmission amplifier 56 and the transmission / reception separation unit 60, and between the transmission / reception separation unit 60 and the reception amplifier 62; And a cancel circuit 66 connected between the signal transmission paths.

The transmission data generation unit 44 generates transmission data such as a command corresponding to transmission information and supplies the transmission data to the transmission amplifier 56. The transmission amplifier 56 receives the transmission data from the transmission data generation unit 44. The carrier wave is modulated by the supplied transmission data to form a transmission signal, which is supplied to the antenna element 26. Further, the transmission phase shift section 54 controls the phase (phase shift amount) of the transmission signal in accordance with a phase control signal supplied from a phase control section (not shown). The reception phase shifter 64 controls the phase (phase shift amount) of the received signal in accordance with a phase control signal supplied from a phase controller (not shown).

FIG. 4 is a diagram for explaining in detail the configuration of the cancel circuit 66 provided in the transmission / reception module 24. As shown in FIG. 4, the cancel circuit 66 has attenuator circuits 68a, 68b, 68c, 68d (hereinafter, unless otherwise distinguished), which are a plurality of attenuation units (four in FIG. 4) each having a different attenuation rate. Is simply referred to as an attenuator circuit 68), and phase shift circuits 70a, 70b, and 70c, which are plural phase shift portions (four in FIG. 4) provided for each of the attenuator circuits 68, each having a different amount of phase shift. , 70d (hereinafter simply referred to as phase shift circuit 70 unless otherwise specified) and a pair of circuit switching units 72 that operate in conjunction with each other to switch circuits. FIG. 5 is a diagram illustrating an example of the attenuator circuit 68 and the phase shift circuit 70. As shown in FIG. 5, the attenuator circuit 68 and the phase shift circuit 70 correspond to the corresponding circuits (the attenuator circuit 68a and the phase shift circuit 70a, the attenuator circuit 68b and the phase shift circuit 70b, the attenuator circuit 68c and the phase shift circuit 70c, An attenuator circuit 68d and a phase shift circuit 70d correspond to each other). These are electric circuits composed of resistors, coils, capacitors, etc., connected in series, depending on the resistance, the number of coils, the capacitance of the capacitors, etc. And have a predetermined amount of attenuation and phase shift (frequency characteristics)! / Speak. The circuit switching unit 72 is, for example, the frequency of the carrier wave output from the local oscillator 20 and the directionality of reception directivity. That is, the attenuator circuit 68a and the phase shift circuit 70a, the attenuator circuit 68b and the phase shift circuit 70b, the attenuator circuit 68c and the phase shift circuit 70c according to the phase shift amount of the reception phase shift unit 64 provided in each transmission / reception module 24. Any one of the attenuator circuit 68d and the phase shift circuit 70d is connected between the signal transmission path between the transmission amplifier 56 and the transmission / reception separation unit 60 and the signal transmission path between the transmission / reception separation unit 60 and the reception amplifier 62. Switch the circuit to connect to. As a result, the carrier wave as a cancel signal output from the transmission amplifier 56 is attenuated by the attenuator circuit 68 and the phase shift circuit 70 with a predetermined attenuation amount, and the phase is controlled with the predetermined phase shift amount and received. By being applied to the circuit on the side, the sneak signal from the transmission side included in the reception signal received by the antenna element 26 is suitably suppressed.

6 and 7 are diagrams illustrating a cancel circuit setting table provided for switching the circuit of the cancel circuit 66. FIG. Preferably, the RFID tag communication device 12 is provided with a plurality of cancel circuit setting tables as shown in FIGS. 6 and 7 corresponding to each transmission / reception module 24. The switching unit 72 performs circuit switching based on the cancel circuit setting table power carrier frequency and directivity direction. Here, FIG. 6 is a table provided for the directivity direction 0 ° in the cancel circuit 66 of the transmission / reception module 24a provided corresponding to the antenna element 26a. Used when the directivity direction determined by the phase shifter 64 is 0 °. Based on this table, in the cancel circuit 66 of the transmission / reception module 24a, when the carrier frequency is f (1) to f (m), the circuit 1, that is, the attenuator circuit 68a and the phase shift circuit 70a, f (m + If it is 1) to f (n), it is circuit 2, that is, an attenuator circuit 68b and a phase shift circuit 70b, and if it is f (n + 1) to f (o), it is circuit 3, that is, an attenuator circuit 68c and a phase shift circuit 70c. , F (o + 1) to f (end), the circuit is switched so that the circuit 4, that is, the attenuator circuit 68d and the phase shift circuit 70d are connected. FIG. 7 is a table provided for a directivity direction of 0 ° in the cancel circuit 66 of the transmission / reception module 24b provided corresponding to the antenna element 26b, and the transmission phase shift unit 54 and Z or the reception shift. Used when the directivity direction determined by the phase section 64 is 0 °. The transmission / reception module In the cancellation circuit 66 of the module 24b, based on this table, when the carrier frequency is f (l) to f (q), the circuit 1, that is, the attenuator circuit 68a and the phase shift circuit 7 Oa, f (q + 1) to If f (r), circuit 2 or attenuator circuit 68b and phase shift circuit 70b, and if f (r + 1) to f (s), circuit 3 or attenuator circuit 68c and phase shift circuit 70c, f ( In the case of s + 1) to f (end), the circuit is switched so that the circuit 4, that is, the attenuator circuit 68d and the phase shift circuit 70d are connected. A similar table is provided for each cancel circuit 66 of the transmission / reception module 24c provided corresponding to the antenna element 26c, and the cancel circuit 66 of each transmission / reception module 24 is provided for each table. Accordingly, the sneak signal from the transmission side included in the reception signal received by the antenna element 26 is suitably suppressed upstream of the reception amplifier 62.

Further, the RFID tag communication device 12 is preferably provided with a plurality of cancel cell circuit setting tables corresponding to the directivity directions, and the circuit switching unit 72 of the cancel circuit 66 includes the plurality of cancel cells. In the circuit setting table, the circuit is switched based on the frequency of the cancel circuit setting table force carrier wave corresponding to the directivity direction determined by the transmission phase shifter 54 and Z or the reception phase shifter 64. FIG. 8 is a table provided for a directivity direction of 10 ° in the cancel circuit 66 of the transmission / reception module 24a provided corresponding to the antenna element 26a, and the transmission phase shift unit 54 and Z or reception phase shift. Used when the directivity direction determined by part 64 is 10 °. Based on this table, the cancel circuit 66 of the transmission / reception module 24a uses the circuit 1, that is, the attenuator circuit 68a and the phase shift circuits 70a, f (t +) when the carrier frequency is f (l) to f (t). l) to f (u), circuit 2 or attenuator circuit 68b and phase shift circuit 70b, and f (u + 1) to f (V), circuit 3 or attenuator circuit 68c and phase shift circuit. In the case of the circuit 70c, f (v + 1) to f (end), the circuit is switched so that the circuit 4, that is, the attenuator circuit 68d and the phase shift circuit 70d are connected. FIG. 9 is a table provided for a directivity direction of 10 ° in the cancel cell circuit 66 of the transmission / reception module 24b provided corresponding to the antenna element 26b. When the directivity direction determined by the phase shifter 64 is 10 ° Used in conjunction. In the cancel circuit 66 of the transmission / reception module 24b, based on this table, when the carrier frequency is f (l) to f (w), the circuit 1, that is, the attenuator circuit 68a and the phase shift circuit 70a, f (w + 1) to f (X), circuit 2, that is, an attenuator circuit 68b and a phase shift circuit 70b, and f (x + 1) to f (y), circuit 3 or an attenuator circuit 68c and In the case of the phase shift circuit 70c, f (y + 1) to f (end), the circuit is switched so that the circuit 4, that is, the attenuator circuit 68d and the phase shift circuit 70d are connected. A similar table is also provided for the cancel circuit 66 of the transmission / reception module 24c provided corresponding to the antenna element 26c, and the cancel circuit 66 of each transmission / reception module 24 switches according to each table. By doing so, the sneak signal from the transmission side included in the reception signal received by the antenna element 26 is suitably suppressed. Preferably, the cancellation circuit setting table is provided for each directivity angle of 10 °, for example, for directivity directions of 20 °, 30 °, and 40 °. Included in the received signal received by the antenna element 26 by performing the circuit switching based on the cancellation circuit setting table corresponding to the directivity direction determined by the unit 54 and Z or the reception phase shift unit 64. The sneak signal from the transmission side is suitably suppressed according to the directivity direction.

FIG. 10 is a diagram for explaining the configuration of the RFID circuit element 76 provided in the RFID tag 14. As shown in FIG. 10, the RFID circuit element 76 has an antenna unit 78 for transmitting and receiving signals to and from the RFID tag communication device 12, and processes a signal received by the antenna unit 78. And an IC circuit unit 80 for performing the above operation. The IC circuit unit 80 stores the rectification unit 82 that rectifies the interrogation wave F received from the RFID tag communication device 12 received by the antenna unit 78, and the energy of the interrogation wave F rectified by the rectification unit 82. Functions as a power supply unit 84, a clock extraction unit 86 that extracts a clock signal from the carrier wave received by the antenna unit 78 and supplies the clock signal to the control unit 92, and an information storage unit that can store a predetermined information signal The RFID circuit element 76 is connected to the memory unit 88, the modulation / demodulation unit 90 connected to the antenna unit 78 to modulate and demodulate signals, the rectification unit 82, the clock extraction unit 86, the modulation / demodulation unit 90, and the like. And a control unit 92 for controlling the operation of the apparatus. The control unit 92 communicates with the wireless tag communication device 12. Control for storing the predetermined information in the memory unit 88 by performing the above, and the interrogation wave F received by the antenna unit 78 based on the information signal stored in the memory unit 88 in the modem unit 90, Then, basic control such as control for reflecting the response wave F back from the antenna unit 78 is executed.

[0037] When the wireless tag communication device 12 communicates with the wireless tag 14, it is preferable that the cancel circuit 66 or the second cancel provided in each transmission / reception module 24 is first processed by the processing described above. After the cancel signal generator 30 that is a circuit is set and the sneak signal from the transmission side is sufficiently suppressed, the transmission signal including the command is transmitted according to the transmission process and the transmission signal as described above. Thus, substantial communication such as processing of a reply signal returned from the wireless tag 14 is performed. In other words, the transmission data generated by the transmission data generation unit 44 is put on a carrier wave in the transmission amplifier 56 of the transmission / reception module 24 and transmitted from the plurality of antenna elements 26 via the transmission / reception module 24 as transmission signals. In addition, the return signals returned in response to the transmission signals are received by the plurality of antenna elements 26, and the received signals are received by the transmission / reception modules 24, the reception signal synthesis unit 28, the cancel signal synthesis unit 32, and the variable amplification unit 34. Then, the homodyne detection is performed by the homodyne detection circuit 36 and stored in the memory unit 40. Then, the detection result stored in the memory unit 40 is read at any time and processed by the response data interpretation unit 42, whereby the response data of the wireless tag 14 is interpreted and the wireless tag 14 is exchanged with the wireless tag 14. Communication takes place.

FIGS. 11 and 12 are diagrams for comparing the difference in noise factor depending on the position where the receiving amplifier is provided in the receiving circuit, and the receiving antenna 94 is connected to the antenna element 26 in the RFID tag communication apparatus 12. The multiplexing unit 96 corresponds to the reception signal combining unit 28 in the RFID tag communication apparatus 12, and the LNA 98 corresponds to the reception amplifier 62 in the RFID tag communication apparatus 12. As shown in FIG. 11, in the receiving circuit for processing the received signal received by the receiving antenna 94, the LNA 98 is not provided on the upstream side of the multiplexing unit 96, but is provided on the downstream side. Then, the gain and noise factor (NF) in each part are as shown in the figure, and the noise factor F of the entire circuit is calculated as 11 1 as shown in the following Equation 1. This value is equivalent to 20.4 (dB), which is a relatively large force. This is because there is a large loss in the multiplexing section 96. On the other hand, as shown in FIG. 12, in the configuration in which the LNA 98 is provided on the upstream side of the multiplexing unit 96, the gain and noise factor (NF) in each unit are as shown in FIG. F is calculated as 93 as shown in Equation 2 below. This value corresponds to 19.7 (dB), and the received signal is sufficiently amplified by the LNA 98 prior to the signal synthesis in the multiplexing unit 96, so that the noise factor of the entire circuit is larger than the configuration shown in FIG. Is kept low! As shown in FIG. 11, when the LNA 98 is provided upstream of the multiplexing unit 96, it is necessary to suppress the sneak signal from the transmission side so that the LNA 98 is not saturated. In the RFID tag communication apparatus 12 of the present embodiment, each transmission / reception module 24 includes the cancel circuit 66, so that the reception amplifier 62 can be provided on the upstream side of the reception signal synthesis unit 28. As a result, the noise factor is reduced. Thus, it is possible to reduce as much as possible the loss when the received signals received by the plurality of antenna elements 26 are combined.

[0039] (Formula 1)

F = f + (f -l) / g + (f -l) / gg + (f -l) / ggg + (f -D / gggg +

0 1 0 2 0 1 3 0 1 2 4 0 1 2 3

= l + (l-l) /0.1+ (1.2-D / O.01 + (10-l) /0.1

= 111

[0040] (Formula 2)

F = f + (f -l) / g + (f -l) / gg + (f -l) / ggg + (f -D / gggg +

0 1 0 2 0 1 3 0 1 2 4 0 1 2 3

= 1+ (1.2-D / O. L + (l-l) / l + (10-l) /0.1

= 93

[0041] Next, another preferred embodiment of the present invention will be described in detail with reference to the drawings. In the following description, portions common to the embodiments are denoted by the same reference numerals and description thereof is omitted.

FIG. 13 is a diagram for explaining the configuration of a wireless tag communication device 100 which is another preferred embodiment of the wireless communication device of the present invention. As shown in FIG. 13, the RFID tag communication apparatus 100 according to the present embodiment includes the transmission / reception modules 102a, 102b, and 102 shown in FIG. 14 described later as an alternative to the transmission / reception module 24 in the RFID tag communication apparatus 12 described above. 102c (hereinafter simply referred to as transceiver module 102 unless otherwise specified) corresponds to each antenna element 26. Is provided. In addition, a signal strength detection unit 104 that detects the signal strength and carrier level of the received signal supplied from each transceiver module 102 is provided.

FIG. 14 is a diagram for explaining in detail the configuration of the transmission / reception module 102 provided in the RFID tag communication apparatus 100 of the present embodiment. As shown in FIG. 14, the transmission / reception module 102 includes a first force bra 106 that is a distribution unit that distributes the transmission signal output from the transmission amplifier 56 to the transmission / reception separation unit 60 and the cancel circuit 66. A second power bra 108 that is an addition unit that outputs the reception signal supplied from the transmission / reception separation unit 60 and the cancellation signal output from the cancellation circuit 66, and a signal transmission path in the transmission / reception module 102. The first circuit switching unit 110, the second circuit switching unit 112, the third circuit switching unit 114, the fourth circuit switching unit 116, and the reception output of the transmission / reception module 102 are combined with the signal strength detection unit 104 and the combination. A fifth circuit switching unit 118 that selectively supplies one of the wave units 28 (to the multiplexing unit 28 at the terminal 1 and to the signal intensity detection unit 104 at the terminal 2) is provided.

[0044] The first force bra 106, for example, distributes the signal so that the output to the cancel circuit 66 side is smaller than the output to the antenna element 26 side. For example, a 10: 1 force bra is used to distribute the signal so that the output to the antenna element 26 side is 10 or more with respect to the output 1 to the Yancell circuit 66 side. In addition, as the second coupler 108, for example, a 3 dB coupler or the like is used. As another configuration, the one shown in FIG. 15 may be considered, and a 3: 1 force bra force may be provided as the first force bra 106 and a 10: 1 force bra may be provided as the second force bra 108. In such a configuration, the cancel signal output from the cancel circuit 66 and the received signal received by the antenna element 26 are respectively added with a predetermined weight in the second force bra 108 which is a calorie calculating unit. Here, the weight of the cancellation signal to be added is smaller than the weight of the reception signal. Preferably, the weight of the cancellation signal added in the second force bra 108 is 1/10 of the weight of the reception signal. Or less. The second force bra 108 is a high-frequency coupler that combines and outputs a cancel signal supplied from the cancel circuit 66 and a received signal received by the antenna element 26 at a predetermined ratio. The transmission amount from the reception signal input side to the output side is the transmission amount from the cancellation signal input side to the output side. It is bigger. Preferably, the ratio of the amount of transmission from the cancel signal input side to the output side to the amount of transmission from the reception signal input side to the output side in the second force bra 108 is 1Z10 or less.

In addition, the first circuit switching unit 110 sends the signal supplied from the transmission / reception separating unit 60 to one of the second force bra 108 and the third circuit switching unit 114 (the second signal at the terminal 1). The circuit is switched so as to be selectively supplied to the power bra 10 8 and to the third circuit switching unit 114 at the terminal 2. Further, the second circuit switching unit 112 sends the signal supplied from the second force bra 108 to one of the receiving amplifier 62 and the third circuit switching unit 114 (in the terminal 1, the receiving amplifier 62 is connected to the terminal In 2, the circuit is switched so as to be selectively supplied to the third circuit switching unit 114. Further, the third circuit switching unit 114 is connected to either the first circuit switching unit 110 or the second circuit switching unit 112 (from the first circuit switching unit 110 for terminal 1 and to the second circuit switching unit for terminal 2). 11 2) The circuit is switched so that the input signal is selectively input to the fourth circuit switching unit 116. The fourth circuit switching unit 116 is input from either the reception amplifier 62 or the third circuit switching unit 114 (from the reception amplifier 62 at the terminal 1 and from the third circuit switching unit 114 at the terminal 2). The circuit is switched so that the received signal is selectively input to the reception phase shifter 64. In a normal operation, the first circuit switching unit 110 is at terminal 1, the second circuit switching unit 112 is at terminal 1, the fourth circuit switching unit 116 is at terminal 1, and the fifth circuit switching unit 118 is at Signals connected to the terminals 1 and output from the transmission / reception separating unit 60 are input to the reception phase-shifting unit 64 via the second force bra 108 and the reception amplifier 62.

Here, in the transmission / reception module 102, the first circuit switching unit 110, the second circuit switching unit 112, and the third circuit switching according to the signal strength and the carrier level detected by the signal strength detection unit 104. Switching of the unit 114 and the fourth circuit switching unit 116 is controlled. Preferably, when the received signal strength detected by the signal strength detection unit 104 is equal to or greater than a predetermined value, the received signal is input to the reception phase shift unit 64 without passing through the reception amplifier 62. Switch the circuit to. That is, the first circuit switching unit 110 is connected to the terminal 1, the second circuit switching unit 112 is connected to the terminal 2, the third circuit switching unit 114 is connected to the terminal 2, and the fourth circuit switching unit 116 is connected to the terminal 2. The output from the second force bra 108 is supplied to the reception phase shifter 64 while avoiding the reception amplifier 62. Thus, the reception By inputting the reception signal to the reception phase shifter 64 without passing through the amplifier 62, the reception amplifier 62 is saturated when a sneak signal from the transmission side included in the reception signal is relatively strong. It can prevent suitably. Also, as will be described later with reference to the flowchart of FIG. 16, the carrier level detected by the signal strength detection unit 104 is compared while switching the attenuator circuit 68 and the phase shift circuit 70 in the cancellation circuit 66, and the signal strength is compared. By setting the lowest circuit, the cancel circuit 66 can be set so that the sneak signal of the transmitting side is suppressed as much as possible. Further, by executing such processing in advance and storing the result as a table, the cancellation table as shown in FIGS. 6 to 9 described above can be created.

[0047] In addition, in the transmission / reception module 102, preferably, when the reception carrier level detected by the signal strength detection unit 104 is less than a predetermined value, a cancellation signal generated by the cancellation circuit 66 is generated. The circuit is switched so that the received signal is input to the received phase shifter 64 without being applied. That is, the first circuit switching unit 110 is connected to the terminal 2, the third circuit switching unit 114 is connected to the terminal 1, the fourth circuit switching unit 116 is connected to the terminal 2, and the output from the transmission / reception separating unit 60 is connected. Is supplied to the reception phase shifter 64 while avoiding the second force bra 108 and the reception amplifier 62. In this case, the second circuit switching unit 112 may be connected to either terminal 1 or 2. In this way, by inputting the reception signal to the reception phase shifter 64 without applying the cancellation signal generated by the cancel circuit 66, it is necessary to apply the cancellation signal so that the reception signal is relatively small. When there is no noise, the generation of noise can be suitably suppressed.

FIG. 16 is a flowchart for explaining a main part of cancel table creation control by the RFID tag communication apparatus 100, which is repeatedly executed at a predetermined cycle.

[0049] First, in step (hereinafter, step is omitted), SA1 is! /, And X that designates the transmission / reception module 102 is set to a. Next, in SA2, the fifth circuit switching unit 118 (SW5) of the transmission / reception module 102x is connected to the terminal 2, and the other fifth circuit switching unit 118 (SW5) of the transmission / reception module 102 is connected to the terminal 1. Next, in S A3, the first circuit switching unit l lO (SWl) is connected to the terminal 1, the second circuit switching unit 112 (SW2) is connected to the terminal 2, and the third circuit switching unit 114 (SW3) is connected to the terminal 2. 4th circuit switching unit 116 (SW4) is connected to terminal 2 respectively. The Next, in SA4, the transmission frequency, that is, the frequency of the carrier wave output from the local oscillator 20 is set. Next, in SA5, the circuit switching unit 72 is switched so that any one of a plurality of sets of attenuator circuits 68 and phase shift circuits 70 provided in the cancel circuit 66 is connected. Next, in SA6, a carrier wave of a predetermined frequency is generated from the local oscillator 20, a transmission signal is transmitted from the antenna element 26 via the transmission / reception module 102, and a reception signal corresponding to the transmission signal is transmitted. Is received by the antenna element 26. Here, the transmission signal transmitted from the antenna element 26 may be transmitted with a carrier wave that does not necessarily include transmission data and does not include a command. Next, in SA7 corresponding to the operation of the signal strength detector 104,

The received carrier level of the combined signal output from the received signal combining unit 28 is detected.

The detection result is stored in a memory unit (not shown). Next, at SA8, it is determined whether or not the received carrier level is stored for all types of the attenuator circuit 68 and the phase shift circuit 70 provided in the cancel circuit 66. If the determination of SA8 is negative, in SA9, the circuit switching unit is connected so that any other set of the attenuator circuit 68 and the phase shift circuit 70 provided in the cancel circuit 66 is connected. If the determination of SA8 is affirmed after 72 is switched, the combination of the attenuator circuit 68 and the phase shift circuit 70 with the lowest stored reception carrier level is determined in SA10. After the frequency is set for the current frequency, it is determined in SA11 whether or not the cancel circuit setting table is filled (completed) for all frequencies. If the determination of SA11 is negative, then in SA12, after the frequency of the carrier wave output from the local oscillator 20 is set to another value, the determination of the force SA11 is performed so that the processing below SA4 is executed again. If so, it is determined in SA13 whether 102x is 102c. If this SA13 decision is denied, the process after SA2 is repeated after the character in X of 102x is replaced with the next alphabet in SA14, but the judgment of SA13 is affirmed. Then, this routine is terminated.

FIG. 17 is a flowchart for explaining a main part of the RFID tag communication control by the RFID tag communication apparatus 100, which is repeatedly executed at a predetermined cycle. [0051] First, in SB1, the fifth circuit switching unit 118 (SW5) is switched to the terminal 2. Next, in SB2, the first circuit switching unit l lO (SWl) is in terminal 2, the second circuit switching unit 112 (SW2) is in terminal 1, and the third circuit switching unit 114 (SW3) is in terminal 1. Fourth circuit switching unit 1 16 (SW4) is connected to terminal 2 respectively. Next, in SB 3, the transmission frequency, that is, the frequency of the carrier wave output from the local oscillator 20 is set, and the transmission phase shift section 54 and Z or the reception phase shift section 64 in each transmission / reception module 24 is shifted. The phase amount (voltage) is set. Next, in SB4, a set of predetermined attenuator circuit 68 and phase circuit 70 is selected and connected in cancel circuit 66 in each transmission / reception module 24 according to the transmission frequency and directivity set in SB3. Next, in SB5, a carrier wave of a predetermined frequency is generated from the local oscillator 20, and a transmission signal including a command is transmitted from the antenna element 26 via the transmission / reception module 102, and according to the transmission signal. A reply signal returned from the wireless tag 14 is received by the antenna element 26. Next, in S B6 corresponding to the operation of the signal strength detecting unit 104, the signal strength (received signal level) of the combined signal output from the received signal combining unit 28 is detected. Next, in SB7, it is determined whether or not the received signal strength detected in SB6 is smaller than a predetermined threshold value. If the determination of SB7 is negative, then in SB9, the fifth circuit switching unit 118 (SW5) is connected to terminal 1 to perform retransmission and re-reception of the reply signal, and then this routine is executed. If the determination of SB7 is affirmed, the first circuit switching unit l lO (SWl) is connected to terminal 1 and the fourth circuit switching unit 116 (SW4) is connected to terminal 1 in SB8. After the connection, the transmission signal to the wireless tag 14 is retransmitted and the return signal is received again at SB9, and then this routine is terminated.

Thus, according to the present embodiment, the array antenna 18 as a receiving antenna in the RFID tag communication device 12 or the like is composed of a plurality of antenna elements 26, and the plurality of antenna elements 26 corresponding to each of the cancel circuit 66 for generating a cancel signal for suppressing the sneak signal from the transmission side included in the received signal received by the antenna element 26, and the cancel circuit 66 A receiving amplifier 62 that is an amplifying unit for amplifying the received signal to which the cancel cell signal is applied. Since the reception signal combining unit 28, which is a combining unit that combines the output signals from the plurality of reception amplifiers 62, is provided, a cancel circuit 66 is provided for each of the plurality of antenna elements 26. Therefore, the receiving amplifier 62 can be provided corresponding to each antenna element 26, and the loss in the received signal combining unit 28 can be sufficiently reduced. That is, it is possible to provide the RFID tag communication apparatus 12 that can reduce as much as possible the loss in combining the received signals respectively received by the plurality of antenna elements 26.

[0053] Further, in correspondence with each of the plurality of antenna elements 26, there is a reception phase shift unit 64 that controls the phase of the output signal from the reception amplifier 62, and the reception signal synthesis unit 28 receives these signals. Since the output signal from the phase shifter 64 is combined, the loss in combining the received signals received by the multiple antenna elements 26 in the array antenna 18 that can control the reception directivity is as much as possible. Can be reduced.

[0054] Further, since the homodyne detection circuit 36 that demodulates the reception signal received by the array antenna 18 is provided, wireless communication including the homodyne detection circuit 36 that is greatly influenced by the sneak signal of the transmission side force. In the apparatus, it is possible to reduce as much as possible the loss when the received signals received by the plurality of antenna elements 26 are combined.

[0055] Further, the cancellation circuit 66 generates an attenuator circuit 68 and a phase shift unit which are a plurality of sets of attenuating units each having different characteristics in order to generate a cancel signal for suppressing a sneak signal on the transmission side. The phase shift circuit 70, and one of the plural sets of attenuator circuits 68 and phase shift circuits 70 is selectively used according to the frequency of the carrier wave of the transmission signal. The configuration of the circuit 66 can be made as simple as possible.

[0056] In addition, a transmission / reception shared array antenna 18 including the plurality of antenna elements 26 is provided, which transmits the transmission signal and receives a reply signal returned from a communication target according to the transmission signal. Therefore, the configuration of the apparatus can be made as simple as possible.

[0057] Further, the transmission signal is transmitted to each antenna corresponding to each of the plurality of antenna elements 26. Since the first force bra 106, which is a distribution unit for distributing to the element 26 and the cancel circuit 66, the output to the cancel circuit 66 side is smaller than the output to the antenna element 26 side is provided. It is possible to reduce the amplification factor of the transmission amplifier 56 used when generating the transmission signal.

[0058] Further, since the output to the cancel circuit 66 side distributed by the first force bra 106 is 1Z10 or less of the output to the antenna element 26 side, the transmission signal transmitted from the array antenna 18 Loss in the first power bra 106 is reduced, and the amplification factor of the transmission amplifier 56 used when generating the transmission signal can be reduced.

[0059] Further, an adder that adds a cancellation signal supplied from the cancellation circuit and a reception signal received by the antenna element 26 with a predetermined weight, corresponding to each of the plurality of antenna elements 26. Since the weight of the cancel signal added by the second force bra 108 is smaller than the weight of the received signal! /, The SN ratio in the reception processing is reduced. Can be improved.

In addition, the second force bra 108 combines a cancel signal supplied from the cancel circuit 66 and a received signal received by the antenna element 26 at a predetermined ratio and outputs the combined signal. The received signal input side force is transmitted to the output side larger than the amount transmitted from the cancel signal input side to the output side, so the loss of the received signal is reduced while canceling. The loss of the signal is relatively large, but there is an advantage that it is not necessary to attenuate it greatly.

[0061] Further, since the weight of the cancellation signal added in the second force bra 108 is 1Z10 or less of the weight of the reception signal, the SN ratio in the reception processing can be improved as much as possible.

[0062] Further, since the ratio of the amount of transmission from the cancel signal input side to the output side to the amount of transmission from the reception signal input side to the output side in the second force bra 108 is 1Z10 or less, the reception signal Loss is less than 10%, and the loss can be kept very small.

[0063] In addition, the signal strength detection unit 10 4 (SA7, SB6) for detecting the signal strength and the carrier level of the received signal has a signal corresponding to each of the plurality of antenna elements 26. A second circuit that switches the circuit so that the received signal is input to the reception phase shifter 64 without passing through the reception amplifier 62 when the received signal strength detected by the intensity detector 104 is equal to or greater than a predetermined value. Since the switching unit 112 and the fourth circuit switching unit 116 are provided, it is possible to suitably prevent the reception amplifier 62 from being saturated when the reception signal is relatively large.

[0064] In addition, when the reception carrier level detected by the signal strength detection unit 104 is less than a predetermined value corresponding to each of the plurality of antenna elements 26, a cancellation signal generated by the cancellation circuit 66 is provided. Since the first circuit switching unit 110 and the fourth circuit switching unit 116 that switch the circuit so that the received signal is input to the reception phase shift unit 64 without applying the signal, the reception carrier level is Noise generation can be suitably suppressed when it is not necessary to apply a relatively small cancel cell signal.

[0065] In addition, since it includes a cancel signal generation unit 30 that is a second cancellation circuit for suppressing the sneak signal from the transmission side included in the output signal from the reception signal synthesis unit 28, The sneak signal of the transmitting side can be suppressed more suitably, and the SN ratio in the reception process can be improved as much as possible.

[0066] In addition, the wireless communication apparatus according to the present embodiment transmits a predetermined transmission signal to the wireless tag 14 that is a communication target by the array antenna 18 as a transmission antenna, and responds to the transmission signal. Since the wireless tag communication device 12 communicates information with the wireless tag 14 by receiving the return signal returned from the wireless tag 14 by the array antenna 18 as a receiving antenna, With regard to the RFID tag communication device 12 that is particularly affected by the sneak signal, the loss when combining the received signals respectively received by the plurality of antenna elements 26 can be reduced as much as possible.

As described above, the preferred embodiment of the present invention has been described in detail with reference to the drawings. The present invention is not limited to this, and may be implemented in still another aspect.

[0068] For example, in the above-described embodiment, the transmission signal is transmitted and the transmission / reception shared by the plurality of antenna elements 26 that receives a return signal returned from the wireless tag 14 in response to the transmission signal. The present invention is applied to a wireless communication apparatus having an array antenna 18 However, the present invention is not limited to this example. For example, as shown in FIG. 18, the transmitting antenna element 122 for transmitting the transmission signal and the transmission signal The present invention may also be applied to a wireless communication apparatus having a transmission / reception module 120 each having a reception antenna element 126 for receiving a reply signal returned in response. In the configuration shown in FIG. 18, the transmission signal output from the transmission amplifier 56 is transmitted from the transmission antenna element 122 via the transmission filter 124 and received by the reception antenna element 126. The signal is supplied to the reception amplifier 62 through the reception filter 128. In this way, since the transmitting antenna 122 and the receiving antenna 126 are individually provided, for example, only the receiving antenna is used as an array antenna. Things to do.

In the above-described embodiment, the cancel circuit 66 provided in each transmission / reception module 24 includes an attenuator circuit 68 that is a plurality of sets of attenuation units having different characteristics and a phase shift circuit 70 that is a phase shift unit. And selectively using one of the plural sets of attenuator circuits 68 and phase shift circuits 70 depending on the carrier frequency of the transmission signal. For example, as shown in FIG. Cancellation phase shifter 1 32 as a variable phase shifter that can change the phase shift amount of the cancel signal based on the carrier wave supplied from amplifier 56, and cancel attenuator 134 as a variable attenuation unit that can change the attenuation factor A transmission / reception module 130 in which a cancellation circuit 136 having the above is provided as an alternative to the cancellation circuit 66 may be applied to the wireless communication apparatus of the present invention. In this configuration, the wraparound signal from the transmission side is suppressed as much as possible corresponding to each antenna element 26 by appropriately controlling the attenuation rate and the phase shift amount in the cancel phase shift section 132 and the cancel attenuator 134. be able to.

In the above-described embodiment, the example in which the present invention is applied to the RFID tag communication device 12 that is an interrogator of the RFID system has been described. However, the present invention is not limited to this. The present invention can be widely applied to a radio communication apparatus having a cancel circuit for suppressing a sneak signal from a transmission side based on a carrier wave component of a transmission signal transmitted from an antenna. Further, in the above-described embodiment, the wireless tag communication device 12 or the like has a power for controlling a cancel signal prior to communication with the wireless tag 14. It is also possible to control the cancel signal in real time during communication.

[0072] In addition, although not illustrated one by one, the present invention is implemented with various modifications without departing from the spirit of the present invention.

Claims

The scope of the claims

[1] A radio that transmits a transmission signal from a transmission antenna and receives a return signal returned from a communication target according to the transmission signal by the reception antenna and performs information communication with the communication target A communication device,

The reception antenna is composed of a plurality of antenna elements, and suppresses a sneak signal from the transmission side included in a reception signal received by the antenna element corresponding to each of the plurality of antenna elements. A cancel circuit for generating a cancel signal and an amplifying unit for amplifying a received signal to which the cancel signal generated by the cancel circuit is applied, and combining output signals from the plurality of amplifying units A wireless communication apparatus comprising a multiplexing unit.

[2] Corresponding to each of the plurality of antenna elements, there is a phase shift unit that controls the phase of the output signal from the amplification unit, and the multiplexing unit combines the output signals from the phase shift unit The wireless communication device according to claim 1, wherein

3. The wireless communication apparatus according to claim 1, further comprising a homodyne detection circuit that demodulates a reception signal received by the reception antenna.

[4] The cancel circuit includes a plurality of sets of attenuation units and phase shift units each having different characteristics in order to generate a cancel signal for suppressing a sneak signal on the transmission side. 4. The wireless communication device according to claim 1, wherein any one of the plurality of sets of attenuating units and phase shifting units is selectively used according to the frequency of the carrier wave.

[5] The cancel circuit includes a variable attenuation unit that can change an attenuation factor and a variable phase shift unit that can change a phase shift amount in order to generate a cancel signal for suppressing a sneak signal of a transmission side force. 4. The wireless communication device according to claim 1, wherein the wireless communication device is capable of controlling an attenuation factor and a phase shift amount in the variable attenuation unit and the variable phase shift unit.

[6] The antenna according to claim 1, further comprising: a transmission / reception shared antenna having a plurality of antenna element powers for transmitting the transmission signal and receiving a return signal returned from a communication target according to the transmission signal. The wireless communication device according to any one of 5.

[7] The transmitting antenna and the receiving antenna are individually provided. The wireless communication device according to claim 1.

[8] An adder that adds the cancel signal supplied by the cancel circuit force and the received signal received by the antenna element with a predetermined weight corresponding to each of the plurality of antenna elements, 8. The wireless communication device according to claim 1, wherein the weight of the cancellation signal added to the unit is smaller than the weight of the reception signal.

[9] The adder unit is a high-frequency coupler that multiplexes and outputs a cancel signal to which the cancel circuit power is also supplied and a reception signal received by the antenna element at a predetermined ratio, and the reception signal input side 9. The wireless communication apparatus according to claim 8, wherein a transmission amount from the output side to the output side is larger than a transmission amount from the cancel signal input side to the output side.

10. The wireless communication apparatus according to claim 8, wherein the weight of the cancel signal added by the adding unit is 1 Z10 or less of the weight of the received signal.

[11] The ratio of the amount of transmission from the cancel signal input side to the output side to the amount of transmission from the reception signal input side to the output side in the adder is 1Z10 or less. Wireless communication device.

[12] A distribution unit for distributing the transmission signal to each antenna element and a cancel circuit corresponding to each of the plurality of antenna elements, and an output to the cancel circuit side distributed by the distribution unit 7. The wireless communication device according to claim 6, wherein is smaller than an output to the antenna element side.

13. The radio communication apparatus according to claim 12, wherein the output to the cancel circuit side distributed by the distribution unit is 1Z10 or less of the output to the antenna element side.

[14] A signal strength detector that detects the signal strength of the received signal, and the received signal strength detected by the signal strength detector corresponding to each of the plurality of antenna elements is a predetermined value or more. 14. The wireless communication device according to claim 1, further comprising a circuit switching unit that switches a circuit so that the received signal is input to the phase shift unit without passing through the amplification unit.

[15] When the received signal strength detected by the signal strength detection unit is less than a predetermined value corresponding to each of the plurality of antenna elements, the cancel circuit generates the received signal strength. 15. The wireless communication according to any one of claims 1 to 14, further comprising a second circuit switching unit that switches a circuit so that the received signal is input to the phase shift unit without applying a cancel signal that is generated. apparatus.

16. The wireless communication device according to claim 1, further comprising a second cancel circuit for suppressing a sneak signal from the transmission side included in the output signal of the combined force.

[17] The wireless communication device transmits a predetermined transmission signal to a wireless tag to be communicated by a transmission antenna, and receives a reply signal returned from the wireless tag in response to the transmission signal. 17. The wireless communication device according to claim 1, wherein the wireless communication device is a wireless tag communication device that communicates information with the wireless tag by being received by a wireless antenna.