JP2008028450A - Radio communication equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide radio communication equipment in which loss caused at composing received signals received respectively by a plurality of antenna elements is reduced to the utmost extent. <P>SOLUTION: An array antenna 18 in radio tag communication equipment 12 or the like comprises the plurality of antenna elements 26, and the radio tag communication equipment 12 is provided with, in accordance with the respective antenna elements 26, cancel circuits 66 for suppressing sneak path signals from a transmission side included in the received signals from the antenna elements 26 and reception amplifiers 62 for amplifying the received signals to which the cancel circuit 66 are applied, and the radio tag communication equipment 12 is further provided with a received signal composite section 28 for composing output signals from the reception amplifiers 62, and since the cancel circuit 26 is provided for each of the antenna elements 26, the reception amplifier 26 can be provided in accordance with each antenna element 26, with the result that loss in the received signal composite section 28 can sufficiently be reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an improvement of a wireless communication apparatus having a cancel circuit for suppressing a sneak signal from a transmission side.

  2. Description of the Related Art A wireless communication device is known that includes 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 is capable of reading information stored in a wireless tag by communication with the wireless tag communication device even when the wireless tag is dirty or disposed at an invisible position. Therefore, practical use is expected in various fields such as merchandise management and inspection processes.

  By the way, normally, the wireless tag communication device transmits a predetermined transmission signal (question wave) from the antenna toward the wireless tag, and a reply signal (response wave) returned from the wireless tag that has received the transmission signal. Is received by the antenna, and information is communicated with the wireless tag. However, a strong sneak signal (direct wave) from the transmission side is mixed in the received reply signal, increasing the overall received signal strength. There is a case. As a result, the allowable input intensity of the amplifier is exceeded, so that the received signal cannot be sufficiently amplified, and as a result, the return signal component from the wireless tag cannot be sufficiently amplified. There was a problem that the to-noise ratio decreased. Therefore, a cancel circuit has been proposed that removes the sneak signal from the transmission side. 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 cancel signal is generated and synthesized with the reception signal, so that the transmission included in the reception signal is transmitted. The sneak signal from the side can be preferably removed.

JP-A-10-62518

  As an example of the wireless communication apparatus, an apparatus that includes an array antenna including a plurality of antenna elements and performs directivity control such as PAA (Phased Array Antenna) processing is known. In this PAA processing, the reception directivity can be controlled by combining (adding) in the multiplexer after controlling the phase of each of the reception signals received by the plurality of antenna elements. Here, in the conventional technique as described above, the cancellation circuit is usually provided so as to remove the sneak signal from the transmission side 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 a multiplexer that synthesizes reception signals respectively received by the plurality of antenna elements. In order to reduce this loss, it is conceivable to provide an amplifier such as an LNA (Low Noise Amplifier) in the receiving circuit. However, in the configuration in which the cancel circuit is provided on the downstream side of the multiplexer, the upstream side of the multiplexer is used. On the side, since the sneak signal from the transmission side is large, it is saturated, so that an amplifier cannot be provided, and the loss in the multiplexer cannot be sufficiently reduced. That is, there has been a demand for the development of a wireless communication device that can reduce loss as much as possible when combining received signals respectively received by a plurality of antenna elements.

  The present invention has been made in the background of the above circumstances, and the object of the present invention is to achieve wireless communication that can reduce loss when combining received signals respectively received by a plurality of antenna elements as much as possible. To provide an apparatus.

  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 return signal returned from a communication target according to the transmission signal is received by a reception antenna. A wireless communication device for communicating information with the communication target, wherein the receiving antenna is composed of a plurality of antenna elements, and each of the antenna elements corresponds to the antenna element. A cancel circuit for generating a cancel signal for suppressing a sneak signal from the transmission side included in the received signal received by the receiver, and an amplifying unit for amplifying the received signal to which the cancel signal generated by the cancel circuit is applied And having a multiplexing unit for synthesizing output signals from the plurality of amplification units. .

  According to this configuration, the receiving antenna is composed of a plurality of antenna elements, and corresponding to each of the plurality of antenna elements, the wraparound from the transmission side included in the received signal received by the antenna element. A cancel circuit that generates a cancel signal for suppressing the signal, and an amplifying unit that amplifies a reception signal to which the cancel signal generated by the cancel circuit is applied, and outputs from the plurality of amplifying units Since it is provided with a multiplexing unit that synthesizes signals, a cancel circuit is provided corresponding to each of the plurality of antenna elements, so that an amplification unit can be provided corresponding to 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 apparatus that can reduce loss when combining received signals respectively received by a plurality of antenna elements as much as possible.

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

  Preferably, a homodyne detection circuit for demodulating a reception signal received by the reception antenna is provided. In this way, in a wireless communication apparatus equipped with a homodyne detection circuit that is greatly influenced by the sneak signal from the transmission side, the loss when combining the received signals respectively received by the plurality of antenna elements is reduced as much as possible. Can be made.

  Preferably, 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 from the transmission side. Any one of the plurality of sets of attenuation units and phase shift units is selectively used according to the frequency of the carrier wave of the transmission signal. In this way, the configuration of the cancel circuit can be made as simple as possible.

  Preferably, the cancel circuit includes a variable attenuator that can change an attenuation factor and a variable phase shift that can change a phase shift amount in order to generate a cancel signal for suppressing a sneak signal from the transmission side. And a damping rate and a phase shift amount in the variable attenuating unit and the variable phase shifting unit can be controlled. In this way, by appropriately controlling the attenuation factor and the amount of phase shift, it is possible to suppress the sneak signal from the transmission side as much as possible corresponding to each antenna element.

  Preferably, the transmission / reception antenna includes a transmission / reception shared antenna including the plurality of antenna elements that transmits the transmission signal and receives a reply signal returned from a communication target according to the transmission signal. In this way, the configuration of the apparatus can be made as simple as possible.

  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.

  Preferably, each of the plurality of antenna elements has a distribution unit for distributing the transmission signal to each antenna element and the cancel circuit, and the distribution unit distributes the transmission signal to the cancel circuit side. The output 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.

  Preferably, the output to the cancel circuit side distributed by the distribution unit is 1/10 or less of the output to the antenna element side. In this way, the loss in the distribution unit of the transmission signal transmitted from the transmission antenna is reduced, and the amplification factor of the amplifier used when generating the transmission signal can be reduced.

  Preferably, an adder that adds a cancellation signal supplied from the cancellation circuit and a reception signal received by the antenna element with a predetermined weight corresponding to each of the plurality of antenna elements. The weight of the cancel signal added in the adding unit is smaller than the weight of the received signal. In this way, the SN ratio in the reception process can be improved.

  Preferably, the adding unit is a high-frequency coupler that combines a cancellation signal supplied from the cancellation circuit and a reception signal received by the antenna element at a predetermined ratio, and outputs the combined signal. The amount of transmission from the 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, but there is an advantage that it is not necessary to greatly attenuate.

  Preferably, the weight of the cancellation signal added by the adding unit is 1/10 or less of the weight of the reception signal. In this way, the SN ratio in the reception process can be improved as much as possible.

  Preferably, a ratio of a transmission amount from the cancel signal input side to the output side to a transmission amount from the reception signal input side to the output side in the addition unit is 1/10 or less. In this way, the loss of the received signal is 10% or less, and the loss can be kept very small.

  Preferably, a signal strength detection unit that detects the 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 is equal to or greater than a predetermined value. In this case, a circuit switching unit that switches circuits so as to input the received signal to the phase shift unit without going through the amplifying unit is provided. In this way, it is possible to suitably prevent the amplification unit from being saturated when the received signal is relatively large.

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

  Preferably, a second cancel circuit for suppressing a sneak signal from the transmission side included in the output signal from the multiplexing unit is provided. In this way, the sneak signal from the transmission side can be more suitably suppressed, and the SN ratio in the reception process can be improved as much as possible.

  Preferably, the wireless communication apparatus transmits a predetermined transmission signal to a wireless tag that is a communication target using a transmission antenna, and a reply signal returned from the wireless tag in response to the transmission signal. Is a wireless tag communication device that communicates information with the wireless tag by receiving the signal with the receiving antenna. In this way, with respect to the RFID tag communication apparatus that is particularly affected by the sneak signal from the transmission side, it is possible to reduce as much as possible the loss when combining the received signals respectively received by the plurality of antenna elements. .

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

FIG. 1 is a diagram illustrating a wireless tag communication system 10 in which a wireless communication device of the present invention is preferably used. The wireless tag communication system 10 includes a wireless tag communication device 12 that is an embodiment of the wireless communication device of the present invention and a single or multiple (single in FIG. 1) wireless communication target of the wireless tag communication device 12. The RFID tag is a so-called RFID (Radio Frequency Identification) system. The RFID tag communication device 12 functions as an interrogator of the RFID system, and the RFID tag 14 functions as a responder. That is, when the interrogation wave F _c (transmission signal) is transmitted from the radio tag communication device 12 toward the radio tag 14, a predetermined command (transmission data) is received in the radio tag 14 that has received the interrogation wave F _c. As a result, the interrogation wave F _c is modulated and sent back to the RFID tag communication apparatus 12 as a response wave F _r (reply signal), so that information is transmitted between the RFID tag communication apparatus 12 and the RFID tag 14. Communication takes place. The wireless tag communication system 10 is used, for example, for managing articles in a predetermined communication area. 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 according to the present embodiment includes a local oscillator 20 that generates a predetermined local signal corresponding to a carrier wave, and a carrier wave amplifier that amplifies the carrier wave output from the local oscillator 20 22 and a plurality of (three in FIG. 2) transmission / reception for transmitting a transmission signal based on the carrier wave supplied from the carrier wave amplification unit 22 from the corresponding antenna element 26 and processing a reception signal received by the antenna element 26 Modules 24a, 24b, and 24c (hereinafter simply referred to as transmission / reception module 24 unless otherwise distinguished) and antenna elements 26a, 26b, and 26c for transmission / reception provided corresponding to the transmission / reception modules 24a, 24b, and 24c ( Hereinafter, the antenna elements 26 are simply referred to unless otherwise distinguished) and the plurality of transmission / reception modules 24 are referred to. A reception signal synthesis unit 28 that is a multiplexing unit that synthesizes (adds) the reception signals supplied from the transmitter, and a cancel signal for suppressing a sneak signal from the transmission side based on the carrier wave supplied from the local oscillator 20. A cancel signal generating unit 30 to generate, a cancel signal combining unit 32 that combines (adds) the combined received signal supplied from the received signal combining unit 28 and the cancel signal supplied from the cancel signal generating unit 30; A variable amplification unit 34 that amplifies the combined signal supplied from the cancel signal combining unit 32, a homodyne detection circuit 36 that detects the combined signal supplied from the variable amplification unit 34, and the homodyne detection circuit 36. An A / D converter 38 for digitally converting the detection result to be digitally converted by the A / D converter 38 A memory unit 40 for storing signals, a response data interpreting unit 42 for reading the signals stored in the memory unit 40 and interpreting response data included in a reply signal from the wireless tag 14, and a carrier wave in the transmission / reception module 24. The transmission data generating unit 44 for generating transmission data to be placed on the mobile station and the cancel control unit 46 for controlling the cancel signal generated by the cancel signal generating unit 30 are provided. In the RFID tag communication apparatus 12 of the present 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 transmission antenna and a reception antenna.

  The cancel signal generation unit 30 is output from a cancel phase shift unit 48, which is a variable phase shifter for controlling the phase using the carrier wave supplied from the local oscillator 20 as a cancel signal, and the cancel phase shift unit 48. A cancel amplifier 50 which is a variable gain amplifier for amplifying the cancel signal to be amplified, and a cancel attenuator which is a variable attenuator for attenuating the cancel signal output from the cancel amplifier 50 and supplying the same to the cancel signal combining unit 32 52. 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 receives from the cancel control unit 46. The phase (phase shift amount) of the carrier wave is controlled in accordance with the supplied phase control signal. 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. The cancel attenuator 52 is supplied from the cancel control unit 46. The amplitude (attenuation amount) of the carrier wave is controlled in accordance with the supplied amplitude control signal. In the RFID tag communication apparatus 12 of the present embodiment, the cancel signal generation unit 30 functions as a second cancellation circuit for suppressing a sneak signal from the transmission side included in the output signal from the reception signal synthesis unit 28. To do.

  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 the transmission phase shifter 54. Provided in a signal transmission path between the transmission amplifier 56 and the antenna element 26, and a transmission amplifier 56 which is a variable gain amplifier for modulating the carrier wave output from the transmission data with predetermined transmission data and outputting the transmission signal. The filter 58 and the transmission signal output from the transmission amplifier 56 are supplied to the antenna element 26 through the filter 58, and are received by the antenna element 26 and supplied through the filter 58. Transmission / reception separating unit 60 for supplying the signal to the receiving amplifier 62 and a variable gain amplifier for amplifying the received signal supplied from the transmission / reception separating unit 60 A reception amplifier 62, a reception phase shifter 64, which is a variable phase shifter for controlling the phase of a reception signal output from the reception amplifier 62, and the transmission amplifier 56 and the transmission / reception separation unit 60. And a cancel circuit 66 connected between the signal transmission path and the signal transmission path between the transmission / reception separating unit 60 and the reception amplifier 62.

  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 transmits the transmission data supplied from the transmission data generation unit 44. The carrier wave is modulated by data to be a transmission signal and supplied to the antenna element 26. The transmission phase shifter 54 controls the phase (phase shift amount) of the transmission signal in accordance with a phase control signal supplied from a phase control unit (not shown). The reception phase shift unit 64 controls the phase (phase shift amount) of the reception signal in accordance with a phase control signal supplied from a phase control unit (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 includes attenuator circuits 68a, 68b, 68c, and 68d (hereinafter, unless otherwise distinguished) that are a plurality of (four in FIG. 4) attenuators having different attenuation factors. Simply referred to as an attenuator circuit 68) and phase shift circuits 70a, 70b, 70c and 70d which are plural (four in FIG. 4) phase shift portions provided corresponding to the respective attenuator circuits 68. (Hereinafter, simply referred to as the phase shift circuit 70 unless otherwise distinguished) and a pair of circuit switching units 72 that switch the circuits by operating in conjunction with each other. 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 corresponding circuits (attenuator circuit 68a and phase shift circuit 70a, attenuator circuit 68b and phase shift circuit 70b, attenuator circuit 68c and phase shift circuit 70c, The attenuator circuit 68d and the phase shift circuit 70d correspond to each other) and are an electric circuit composed of a resistor, a coil, a capacitor, and the like that are connected in series. Attenuation amount and phase shift amount (frequency characteristics). For example, the circuit switching unit 72 corresponds to the frequency of the carrier wave output from the local oscillator 20 and the reception directivity direction, that is, the amount of phase shift of the reception phase shift unit 64 provided in each transmission / reception module 24. And any one of 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, the attenuator circuit 68d and the phase shift circuit 70d are arranged between the transmission amplifier 56 and the transmission / reception separating unit 60. The circuit is switched so as to be connected between the signal transmission path and the signal transmission path between the transmission / reception separating unit 60 and the reception amplifier 62. 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 by a predetermined attenuation amount, and the phase is controlled by the predetermined phase shift amount, and the circuit on the receiving side. As a result, 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 wireless 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, and the circuit switching unit of the cancel circuit 66. 72 switches the circuit based on the frequency and directivity direction of the carrier wave from the cancel circuit setting table. Here, FIG. 6 is a table provided for a directivity direction of 0 ° 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 / or reception. This is used when the directivity direction determined by the phase shift unit 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 circuits 70a, f (m + 1) to In the case of f (n), the circuit 2, that is, the attenuator circuit 68b and the phase shift circuit 70b, and in the case of f (n + 1) to f (o), the circuit 3, that is, the attenuator circuit 68c and the 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. The transmission phase shift unit 54 and / or the reception shift is shown in FIG. Used when the directivity direction determined by the phase part 64 is 0 °. In the cancel circuit 66 of the transmission / reception module 24b, based on this table, when the carrier frequency is f (1) to f (q), the circuit 1, that is, the attenuator circuit 68a and the phase shift circuits 70a, f (q + 1) to In the case of f (r), the circuit 2, that is, the attenuator circuit 68b and the phase shift circuit 70b, and in the case of f (r + 1) to f (s), the circuit 3, that is, the attenuator circuit 68c and the phase shift circuit 70c, f (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. An equivalent table is also provided for the cancel circuit 66 of the transmission / reception module 24c provided corresponding to the antenna element 26c, and the cancellation circuit 66 of each transmission / reception module 24 is switched according to each table. The sneak signal from the transmission side included in the reception signal received by the antenna element 26 is suitably suppressed on the upstream side of the reception amplifier 62.

  The RFID tag communication device 12 is preferably provided with a plurality of cancel circuit setting tables corresponding to directivity directions, and the circuit switching unit 72 of the cancel circuit 66 includes the plurality of cancel circuits. The circuit is switched based on the frequency of the carrier wave from the cancel circuit setting table corresponding to the directivity direction determined by the transmission phase shifter 54 and / or the reception phase shifter 64 in the setting table. 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 section 54 and / or the reception phase shift section. This is used when the directivity direction determined by 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 circuit 70a, f (t + 1) to f (t) when the carrier frequency is f (1) to f (t). In the case of f (u), the circuit 2, that is, the attenuator circuit 68b and the phase shift circuit 70b, and in the case of f (u + 1) to f (v), the circuit 3, that is, the attenuator circuit 68c and the phase shift 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 circuit 66 of the transmission / reception module 24b provided corresponding to the antenna element 26b, and the transmission phase shift unit 54 and / or the reception shift. It is used when the directivity direction determined by the phase part 64 is 10 °. Based on this table, the cancel circuit 66 of the transmission / reception module 24b uses the circuit 1, that is, the attenuator circuit 68a and the phase shift circuits 70a, f (w + 1) to f (1) to f (1) to f (w). In the case of f (x), the circuit 2, that is, the attenuator circuit 68b and the phase shift circuit 70b, and in the case of f (x + 1) to f (y), the circuit 3, that is, the attenuator circuit 68c and 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. An equivalent table is also provided for the cancel circuit 66 of the transmission / reception module 24c provided corresponding to the antenna element 26c, and the cancellation circuit 66 of each transmission / reception module 24 is switched according to each table. The sneak signal from the transmission side included in the reception signal received by the antenna element 26 is preferably suppressed. Preferably, the cancellation circuit setting table is provided for every 10 ° directivity angle, for example, for the directivity direction 20 °, 30 °, 40 °,... Transmission included in the received signal received by the antenna element 26 by performing the circuit switching based on the cancel circuit setting table corresponding to the directivity direction determined by the unit 54 and / or the reception phase shift unit 64. The sneak signal from the 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 performs processing of signals received by the antenna unit 78 and an antenna unit 78 for transmitting and receiving signals to and from the RFID tag communication device 12. And an IC circuit unit 80 for this purpose. The IC circuit unit 80 rectifies the interrogation wave F _c received from the RFID tag communication device 12 received by the antenna unit 78 and the energy of the interrogation wave F _c rectified by the rectification unit 82. Functions as a power supply unit 84 for storing, 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 via 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 functionally includes a control unit 92 for controlling the operation. The control unit 92 performs control for storing the predetermined information in the memory unit 88 by communicating with the RFID tag communication device 12, and the modulation / demodulation unit 90 receives the interrogation wave F _c received by the antenna unit 78. Then, basic control such as control for reflecting and returning the response wave _Fr as the response wave _Fr is executed based on the information signal stored in the memory unit 88.

  When communicating with the wireless tag 14 by the wireless tag communication device 12, it is preferable that the cancel circuit 66 or the second cancel circuit provided in each transmission / reception module 24 is firstly processed by the processing as described above. After the setting of the signal generation unit 30 is performed and the sneak signal from the transmission side is sufficiently suppressed, the wireless tag 14 is processed according to the transmission processing of the transmission signal including the command and the transmission signal as described above. Substantial communication such as processing of a reply signal returned from is performed. That is, 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 as transmission signals from the plurality of antenna elements 26 via the transmission / reception module 24. In addition, the return signals returned in response to the transmission signals are received by the plurality of antenna elements 26, and the reception 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 circuit 36 performs homodyne detection and stores it 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. Communication takes place.

  FIGS. 11 and 12 are diagrams for explaining the difference in noise factor depending on the position where the receiving amplifier is provided in the receiving circuit. The receiving antenna 94 is connected to the antenna element 26 in the RFID tag communication apparatus 12 and a multiplexing unit. Reference numeral 96 corresponds to the reception signal combining unit 28 in the wireless tag communication apparatus 12, and LNA 98 corresponds to the reception amplifier 62 in the wireless 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. 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 111 as shown in the following Equation 1. This value corresponds to 20.4 (dB) and is a relatively large value, which is due to a large loss in the multiplexing unit 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. 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 synthesis of the signal 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 on the upstream side 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 according to the present embodiment, since each transmission / reception module 24 includes the cancel circuit 66, the reception amplifier 62 can be provided on the upstream side of the reception signal combining unit 28. As a result, the noise factor is reduced. Thus, it is possible to reduce as much as possible the loss when combining the reception signals respectively received by the plurality of antenna elements 26.

(Formula 1)
F = f ₀ + (f ₁ −1) / g ₀ + (f ₂ −1) / g ₀ g ₁ + (f ₃ −1) / g ₀ g ₁ g ₂ + (f ₄ −1) / g ₀ g ₁ g ₂ g ₃ + ...
= 1 + (1-1) /0.1+ (1.2-1) /0.01+ (10-1) /0.1
= 111

(Formula 2)
F = f ₀ + (f ₁ −1) / g ₀ + (f ₂ −1) / g ₀ g ₁ + (f ₃ −1) / g ₀ g ₁ g ₂ + (f ₄ −1) / g ₀ g ₁ g ₂ g ₃ + ...
= 1 + (1.2-1) /0.1+ (1-1) / 1 + (10-1) /0.1
= 93

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

  FIG. 13 is a diagram illustrating the configuration of a wireless tag communication device 100 that 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 transmission / reception modules 102a, 102b, and 102c (hereinafter referred to as FIG. 14), which will be described later, as an alternative to the transmission / reception module 24 in the RFID tag communication apparatus 12 described above. If not particularly distinguished, they are simply referred to as transmission / reception modules 102) corresponding to each antenna element 26. Further, a signal strength detection unit 104 that detects the signal strength of the reception signal supplied from each transmission / reception 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 coupler 106 that is a distribution unit that distributes a transmission signal output from the transmission amplifier 56 to the transmission / reception separation unit 60 and a cancel circuit 66, and the transmission / reception module. A first coupler that switches a signal transmission path in the transmission / reception module 102, and a second coupler 108 that adds and outputs a reception signal supplied from the separation unit 60 and a cancellation signal output from the cancellation circuit 66 110, second circuit switching unit 112, third circuit switching unit 114, fourth circuit switching unit 116, and the received output of the transmission / reception module 102 is one of the signal strength detection unit 104 and the multiplexing unit 28. On the other hand, the fifth circuit switching unit 118 that selectively supplies the signal to the multiplexing unit 28 at the terminal 1 and the signal strength detection unit 104 at the terminal 2; , It is equipped.

  For example, the first coupler 106 distributes a signal so that an output to the cancel circuit 66 side is smaller than an output to the antenna element 26 side. For example, a 10: 1 coupler or the like that distributes the signal so that the output to the antenna element 26 side with respect to the output 1 is 10 or more is used. For example, a 3 dB coupler is used as the second coupler 108. As another configuration, one shown in FIG. 15 may be considered, and a 3 dB coupler may be provided as the first coupler 106 and a 10: 1 coupler may be provided as the second coupler 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 added with a predetermined weight in the second coupler 108 which is an adder. 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 by the second coupler 108 is 1/10 to the weight of the reception signal. Is less than that. The second coupler 108 is a high frequency coupler that multiplexes and outputs the cancel signal supplied from the cancel circuit 66 and the received signal received by the antenna element 26 at a predetermined ratio. The amount of transmission from the signal input side to the output side is larger than the amount of transmission from the cancel signal input side to the output side. 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 second coupler 108 is 1/10 or less.

  The first circuit switching unit 110 sends the signal supplied from the transmission / reception separating unit 60 to one of the second coupler 108 and the third circuit switching unit 114 (in the terminal 1, the terminal is connected to the second coupler 108. 2, the circuit is switched so as to be selectively supplied to the third circuit switching unit 114. In addition, the second circuit switching unit 112 sends the signal supplied from the second coupler 108 to one of the reception amplifier 62 and the third circuit switching unit 114 (in the terminal 1, to the reception amplifier 62, in the terminal 2). The circuit is switched so as to be selectively supplied to the third circuit switching unit 114. In addition, 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 at the terminal 1 and from the second circuit switching unit at the terminal 2). 112), 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 a signal is selectively input to the reception phase shifter 64. In normal operation, the first circuit switching unit 110 is connected to the terminal 1, the second circuit switching unit 112 is connected to the terminal 1, the fourth circuit switching unit 116 is connected to the terminal 1, and the fifth circuit switching unit 118 is connected to the terminal 1. Signals connected to the terminals 1 and output from the transmission / reception separator 60 are input to the reception phase shifter 64 via the second coupler 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, the third circuit switching unit 114, and the fourth circuit according to the signal strength detected by the signal strength detection unit 104. Switching of the 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. 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 coupler 108 is supplied to the reception phase shifter 64 while avoiding the reception amplifier 62. As described above, when the reception signal is input to the reception phase shifter 64 without passing through the reception amplifier 62, the reception amplifier is used when a sneak signal from the transmission side included in the reception signal is relatively strong. It is possible to suitably prevent 62 from being saturated. Further, as described later with reference to the flowchart of FIG. 16, the signal strength detected by the signal strength detection unit 104 is compared while switching between the attenuator circuit 68 and the phase shift circuit 70 in the cancel circuit 66, and the signal strength is compared. By setting the lowest circuit, the cancel circuit 66 can set the sneak signal from the transmission side as much as possible. Further, by performing such processing in advance and storing the result as a table, the cancellation table as shown in FIGS. 6 to 9 can be created.

  In the transceiver module 102, preferably, when the received signal strength detected by the signal strength detector 104 is less than a predetermined value, the cancel signal generated by the cancel circuit 66 is not applied. The circuit is switched so that the reception signal is input to the reception phase shifter 64. 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 The two couplers 108 and the reception amplifier 62 are avoided and supplied to the reception phase shifter 64. In this case, the second circuit switching unit 112 may be connected to either of the terminals 1 and 2. In this way, by inputting the reception signal to the reception phase shifter 64 without applying the cancellation signal generated by the cancellation circuit 66, the reception signal is relatively small and it is not necessary to apply the cancellation signal. In such a case, 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, and is repeatedly executed at a predetermined cycle.

  First, in step (hereinafter, step is omitted) SA1, x specifying 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 SA3, the first circuit switching unit 110 (SW1) is connected to the terminal 1, the second circuit switching unit 112 (SW2) is connected to the terminal 2, the third circuit switching unit 114 (SW3) is connected to the terminal 2, Four-circuit switching unit 116 (SW4) is connected to terminal 2 respectively. 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 Received by the antenna element 26. Here, the transmission signal transmitted from the antenna element 26 does not necessarily need to carry transmission data, and a carrier wave not including a command may be transmitted. Next, in SA7 corresponding to the operation of the signal strength detection unit 104, the signal strength (reception carrier level) of the combined signal output from the reception signal combining unit 28 is detected, and the detection result is stored in a memory unit (not shown). Remembered. Next, at SA8, it is determined whether or not the received carrier level is stored for all types of attenuator circuits 68 and phase shift circuits 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 circuits 68 and the phase shift circuit 70 provided in the cancel circuit 66 is connected. After switching 72, the processing below SA5 is executed again. However, if the determination at SA8 is affirmative, at SA10, the stored attenuator circuit 68 having the lowest received carrier level and the phase shift circuit 70 are After the set is set for the frequency at that time, 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, the SA4 and subsequent processes are executed again after the frequency of the carrier wave output from the local oscillator 20 is set to another value in SA12. If YES is determined, it is determined in SA13 whether 102x is 102c. When the determination of SA13 is negative, the process after SA2 is repeated after the character in x of 102x is replaced with the next alphabet in SA14, but when the determination of SA13 is positive, This routine is then terminated.

  FIG. 17 is a flowchart for explaining a main part of the RFID tag communication control by the RFID tag communication apparatus 100, and is repeatedly executed at a predetermined cycle.

  First, in SB1, the fifth circuit switching unit 118 (SW5) is switched to the terminal 2. Next, in SB2, the first circuit switching unit 110 (SW1) is connected to the terminal 2, the second circuit switching unit 112 (SW2) is connected to the terminal 1, the third circuit switching unit 114 (SW3) is connected to the terminal 1, Four-circuit switching unit 116 (SW4) is connected to terminal 2 respectively. Next, in SB3, the transmission frequency, that is, the frequency of the carrier wave output from the local oscillator 20 is set, and the phase shift amount (voltage) of the transmission phase shifter 54 and / or the reception phase shifter 64 in each transmission / reception module 24 is set. ) Is set. Next, in SB4, the cancel circuit 66 in each transmission / reception module 24 selects and connects a predetermined attenuator circuit 68 and phase circuit 70 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, a transmission signal including a command is transmitted from the antenna element 26 via the transmission / reception module 102, and the transmission signal includes the transmission signal according to the transmission signal. A reply signal returned from the wireless tag 14 is received by the antenna element 26. Next, in SB6 corresponding to the operation of the signal strength detection unit 104, the signal strength (reception 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 at SB7 is negative, at SB9, after the fifth circuit switching unit 118 (SW5) is connected to the terminal 1 and re-transmission and re-reception of the reply signal are performed, this routine is executed. If the determination of SB7 is affirmed, in SB8, the first circuit switching unit 110 (SW1) is connected to the terminal 1 and the fourth circuit switching unit 116 (SW4) is connected to the terminal 1, respectively. After the connection, in SB9, the transmission signal is retransmitted to the wireless tag 14 and the return signal is re-received, 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 corresponds to each of the plurality of antenna elements 26. The cancel circuit 66 for generating a cancel signal for suppressing the sneak signal from the transmission side included in the reception signal received by the antenna element 26 and the cancel signal generated by the cancel circuit 66 are applied. A receiving amplifier 62 that is an amplifying unit that amplifies the received signal, and a reception signal combining unit 28 that is a combining unit that combines output signals from the plurality of receiving amplifiers 62. Since the cancel circuit 66 is provided corresponding to each of the plurality of antenna elements 26, each antenna Corresponding to the child 26 may be provided with a receiving amplifier 62, and by extension can be sufficiently reduced loss in the received signal synthesizing unit 28. In other words, it is possible to provide the wireless tag communication device 12 that can reduce loss as much as possible when combining received signals respectively received by the plurality of antenna elements 26.

  In addition, corresponding to each of the plurality of antenna elements 26, it has 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 includes the reception phase shift unit 64. Since the output signals from the antennas are combined, the loss when combining the reception signals respectively received by the plurality of antenna elements 26 in the array antenna 18 capable of controlling the reception directivity can be reduced as much as possible. it can.

  In addition, since a homodyne detection circuit 36 that demodulates a reception signal received by the array antenna 18 is provided, in the wireless communication apparatus including the homodyne detection circuit 36 that has a large influence of a sneak signal from the transmission side, Loss when combining the received signals respectively received by the antenna elements 26 can be reduced as much as possible.

  The cancel circuit 66 generates a cancel signal for suppressing a sneak signal from the transmitting side, and a plurality of sets of attenuator circuits 68 having different characteristics and a phase shift circuit serving as a phase shift unit. 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. It can be as simple as possible.

  In addition, since the transmission signal is transmitted and the return signal returned from the communication target according to the transmission signal is received, the transmission / reception shared array antenna 18 including the plurality of antenna elements 26 is provided. The configuration of the apparatus can be made as simple as possible.

  Further, the output to the cancel circuit 66 side for distributing the transmission signal to each antenna element 26 and the cancel circuit 66 corresponding to each of the plurality of antenna elements 26 is more than the output to the antenna element 26 side. Since the first coupler 106, which is a small distribution unit, is provided, the amplification factor of the transmission amplifier 56 used when generating the transmission signal can be reduced.

  Further, since the output to the cancel circuit 66 side distributed by the first coupler 106 is 1/10 or less of the output to the antenna element 26 side, the first coupler of the transmission signal transmitted from the array antenna 18 is used. The loss in 106 is reduced, and the amplification factor of the transmission amplifier 56 used when generating the transmission signal can be reduced.

  A second coupler that is 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. 108, and the weight of the cancellation signal added in the second coupler 108 is smaller than the weight of the reception signal, so that the SN ratio in the reception processing can be improved.

  The second coupler 102 is a high-frequency coupler that combines a cancellation signal supplied from the cancellation circuit 66 and a reception signal received by the antenna element 26 at a predetermined ratio, and outputs the combined signal. Since the transmission amount from the signal input side to the output side is larger than the transmission amount from the cancellation signal input side to the output side, the loss of the reception signal is reduced, while the loss of the cancellation signal is relatively large. On the contrary, there is an advantage that it is not necessary to greatly attenuate.

  Further, since the weight of the cancellation signal added in the second coupler 108 is 1/10 or less of the weight of the reception signal, the SN ratio in the reception process can be improved as much as possible.

  Further, since the ratio of the transmission amount from the cancel signal input side to the output side to the transmission amount from the reception signal input side to the output side in the second coupler 108 is 1/10 or less, the loss of the reception signal is reduced. It becomes 10% or less, and the loss can be suppressed very small.

  The signal strength detection unit 104 (SA7, SB5) for detecting the signal strength of the received signal has a received signal strength detected by the signal strength detection unit 104 corresponding to each of the plurality of antenna elements 26. Is equal to or greater than a predetermined value, the second circuit switching unit 112 and the fourth circuit switching unit 116 are configured to switch circuits so that the reception signal is input to the reception phase shift unit 64 without passing through the reception amplifier 62. Since it is provided, it is possible to suitably prevent the reception amplifier 62 from being saturated when the reception signal is relatively large.

  In addition, when the received signal strength detected by the signal strength detection unit 104 is less than a predetermined value corresponding to each of the plurality of antenna elements 26, the cancel signal generated by the cancel circuit 66 is applied. Since the first circuit switching unit 110 and the fourth circuit switching unit 116 for switching the circuit so that the received signal is input to the reception phase shift unit 64 without being received, the received signal is relatively small and the cancel signal The generation of noise can be suitably suppressed when it is not necessary to apply.

  Further, since the cancel signal generation unit 30 that is a second cancel circuit for suppressing the sneak signal from the transmission side included in the output signal from the reception signal synthesis unit 28 is provided, The sneak signal can be further suitably suppressed, and the SN ratio in the reception process can be improved as much as possible.

  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 to the wireless tag 14. Since the wireless tag communication device 12 communicates information with the wireless tag 14 by receiving the return signal returned from the array antenna 18 as a receiving antenna, the influence of the sneak signal from the transmission side With regard to the RFID tag communication device 12 having a particularly large value, loss when combining the reception signals respectively received by the plurality of antenna elements 26 can be reduced as much as possible.

  The preferred embodiments of the present invention have been described in detail with reference to the drawings. However, the present invention is not limited to these embodiments, and may be implemented in other modes.

  For example, in the above-described embodiment, the transmission / reception shared array antenna 18 composed of the plurality of antenna elements 26 that transmits the transmission signal and receives a reply signal returned from the wireless tag 14 according to the transmission signal. However, the present invention is not limited to this, for example, as shown in FIG. 18, for transmission for transmitting the transmission signal. The present invention may be applied to a wireless communication apparatus having a transmission / reception module 120 that individually includes an antenna element 122 and a receiving antenna element 126 for receiving a return signal returned in response to the transmission signal. Absent. 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 the reception signal received by the reception antenna element 126 is 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, the configuration of the apparatus can be varied, for example, only the receiving antenna is an array antenna. be able to.

  Further, 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. One of the attenuator circuit 68 and the phase shift circuit 70 is selectively used depending on the frequency of the carrier wave of the transmission signal. For example, as shown in FIG. A cancel circuit 136 having a cancel phase shifter 132 as a variable phase shifter capable of changing the phase shift amount of a cancel signal based on a carrier wave, and a cancel attenuator 134 as a variable attenuator capable of changing the attenuation factor. A transmission / reception module 130 provided as an alternative to the cancel 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 amount of phase shift in the cancel phase shift unit 132 and the cancel attenuator 134. Can do.

  In the above-described embodiment, the example in which the present invention is applied to the RFID tag communication device 12 or the like that is an interrogator of the RFID system has been described. However, the present invention is not limited to this, and from the transmitting antenna. The present invention can be widely applied to a radio communication apparatus having a cancel circuit for suppressing a sneak signal from the transmission side based on a carrier wave component of a transmission signal to be transmitted.

  In the above-described embodiment, the wireless tag communication device 12 or the like controls the cancel signal prior to the communication with the wireless tag 14, but during the communication with the wireless tag 14. The cancel signal may be controlled in real time.

  In addition, although not illustrated one by one, the present invention is implemented with various modifications within a range not departing from the gist thereof.

It is a figure explaining the radio | wireless tag communication system with which the radio | wireless communication apparatus of this invention is used suitably. It is a figure explaining the structure of the radio | wireless tag communication apparatus which is one Example of the radio | wireless communication apparatus of this invention. It is a figure explaining in detail the structure of the transmission / reception module with which the RFID tag communication apparatus of FIG. 2 was equipped. It is a figure explaining in detail the structure of the cancellation circuit with which the transmission / reception module of FIG. 3 was equipped. FIG. 5 is a diagram illustrating an example of an attenuator circuit and a phase shift circuit in the cancel circuit of FIG. 4. 3 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. 7 is a table 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. 3 is a table provided for a directivity direction of 10 ° in a cancel circuit of a transmission / reception module provided corresponding to a predetermined antenna element in the RFID tag communication apparatus of 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. It is a figure explaining the structure of the RFID circuit element with which the RFID tag which is a communication object of the RFID tag communication apparatus of FIG. 2 was equipped. It is a figure explaining the difference of the noise factor by the position which provides a receiving amplifier in a receiving circuit, and is a figure which illustrates the structure which is not provided with LNA upstream from a multiplexing part. It is a figure explaining the difference of the noise factor by the position which provides a receiving amplifier in a receiving circuit, and is a figure which illustrates the structure provided with LNA upstream from a multiplexing part. It is a figure explaining the structure of the radio | wireless tag communication apparatus which is another suitable Example of the radio | wireless communication apparatus of this invention. It is a figure explaining the structure of the transmission / reception module with which the RFID tag communication apparatus of FIG. 13 was equipped in detail. It is a figure explaining in detail the structure of the other transmission / reception module with which the RFID tag communication apparatus of FIG. 13 was equipped. It is a flowchart explaining the principal part of cancellation table creation control by the radio | wireless tag communication apparatus of FIG. It is a flowchart explaining the principal part of the RFID tag communication control by the RFID tag communication apparatus of FIG. FIG. 3 is a diagram illustrating in detail a configuration of a transmission / reception module that is suitably provided in the RFID tag communication apparatus of FIG. The configuration of a transmission / reception module including a cancel circuit having a variable attenuation unit that can change the attenuation factor and a variable phase shift unit that can change the amount of phase shift, which is preferably provided in the RFID tag communication apparatus of FIG. FIG.

Explanation of symbols

12, 100: RFID tag communication device (wireless communication device)
14: Wireless tag (communication target)
18: Array antenna (transmitting / receiving antenna)
26: Antenna element 28: Received signal combining unit (multiplexing unit)
30: Cancel signal generator (second cancel circuit)
36: homodyne detection circuit 62: receiving amplifier (amplifying unit)
64: reception phase shifter 66, 136: cancel circuit 68: attenuator circuit (attenuator)
70: Phase shift circuit (phase shift section)
104: Signal strength detection unit 106: First coupler (distribution unit)
108: Second coupler (adder)
110: first circuit switching unit 112: second circuit switching unit 114: third circuit switching unit 116: fourth circuit switching unit 122: transmitting antenna element 126: receiving antenna element 132: cancel phase shifting unit (variable phase shifting unit) Part)
134: Cancel attenuator (variable attenuation unit)

Claims (17)

A wireless communication apparatus that transmits a transmission signal from a transmission antenna and receives a reply signal returned from a communication target according to the transmission signal by a reception antenna and communicates information with the communication target. And
The receiving antenna is composed of a plurality of antenna elements, and suppresses a sneak signal from the transmitting side included in a received 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 reception signal to which the cancel signal generated by the cancel circuit is applied, and combining the output signals from the plurality of amplifying units A wireless communication apparatus comprising a unit.   Corresponding to each of the plurality of antenna elements, it has a phase shift unit that controls the phase of the output signal from the amplification unit, and the multiplexing unit synthesizes the output signals from these phase shift units. The wireless communication apparatus according to claim 1.   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.   The cancel circuit has 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 from the transmission side, and the frequency of the carrier wave of the transmission signal 4. The wireless communication device according to claim 1, wherein any one of the plurality of sets of attenuation units and phase shift units is selectively used according to the frequency.   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 from the transmission side. The wireless communication apparatus according to any one of claims 1 to 3, wherein the attenuation rate and the amount of phase shift in the variable attenuation unit and the variable phase shift unit can be controlled.   6. The antenna according to claim 1, further comprising: a transmission / reception shared antenna including the plurality of antenna elements that transmits the transmission signal and receives a reply signal returned from a communication target according to the transmission signal. Wireless communication device.   6. The wireless communication apparatus according to claim 1, wherein the transmitting antenna and the receiving antenna are individually provided.   Corresponding to each of the plurality of antenna elements, an adder that adds a cancel signal supplied from the cancel circuit and a received signal received by the antenna element with a predetermined weight is added in the adder. The wireless communication apparatus according to claim 1, wherein a weight of the cancel signal is smaller than a weight of the received signal.   The adding unit is a high-frequency coupler that outputs a cancellation signal supplied from the cancellation circuit and a reception signal received by the antenna element at a predetermined ratio, and outputs from the reception signal input side to the output side The wireless communication device according to claim 8, wherein a transmission amount to the transmission signal is larger than a transmission amount from the cancel signal input side to the output side.   The wireless communication apparatus according to claim 8 or 9, wherein the weight of the cancellation signal added by the adding unit is 1/10 or less of the weight of the reception signal.   11. The wireless communication device according to claim 8, wherein a ratio of a transmission amount from the cancel signal input side to the output side to a transmission amount from the reception signal input side to the output side in the adder is 1/10 or less. .   Corresponding to each of the plurality of antenna elements, it has a distribution unit for distributing the transmission signal to each antenna element and cancellation circuit, and the output to the cancellation circuit side distributed by the distribution unit is directed to the antenna element side The wireless communication apparatus according to claim 6, wherein the output is smaller than   The wireless communication apparatus according to claim 12, wherein the output to the cancel circuit side distributed by the distribution unit is 1/10 or less of the output to the antenna element side.   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 greater than or equal to a predetermined value; The wireless communication apparatus 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 going through an amplification unit.   Corresponding to each of the plurality of antenna elements, when the received signal strength detected by the signal strength detector is less than a predetermined value, the received signal is not applied without applying the cancel signal generated by the cancel circuit. The wireless communication device according to claim 1, further comprising a second circuit switching unit that switches a circuit so as to be input to the phase shift unit.   16. The radio communication apparatus according to claim 1, further comprising a second cancel circuit for suppressing a sneak signal from a transmission side included in an output signal from the multiplexing unit.   The wireless communication device transmits a predetermined transmission signal to a wireless tag that is a communication target by a transmission antenna, and transmits a reply signal returned from the wireless tag in response to the transmission signal by the reception antenna. 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 receiving the information.

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