JP2002015288A - RFID multi-purpose interrogator - Google Patents

Abstract

(57) [Summary] [PROBLEMS] An R with high individual identification processing capability that avoids interference with a foreign wave and performs multiple communications with a plurality of transponders having different frequencies.
Provide FID interrogator. The interrogator includes a control unit for controlling the whole.
A data conversion unit 11, a transmission / reception data switching unit 12,
The transmitting unit 13, the receiving unit 14, and the composite antenna unit 16 are main components. The inquiry message of the parallel digital signal generated by the control unit 10 modulates the carrier of the transmission unit 13 via the data conversion unit 11 and the transmission / reception data switching unit 12, and transmits the modulated signal from the composite antenna unit 16. The response message received by the composite antenna unit 16 is demodulated by the receiving unit 14 and input to the control unit 10 via the transmission / reception data switching unit 12 and the data conversion unit 11 to perform individual identification processing. The receiving unit 14 intercepts an extraneous wave, and the transmitting unit 13 transmits a plurality of frequencies not affected by the extraneous wave from the composite antenna unit 16 and performs multiplex communication with a plurality of transponders having different frequencies.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an RFID device for non-contact identification using an electromagnetic wave as a medium.

[0002]

2. Description of the Related Art An interrogator receives an electromagnetic wave of a question transmitted by an interrogator, receives an electromagnetic wave to which information such as an attribute returned from the transponder is added, and the interrogator receives the electromagnetic wave. (Radio frequency ide
An apparatus has been developed. The frequencies of electromagnetic waves that can be used in this RFID device (hereinafter abbreviated as the device) are dispersed in a long wave to short wave band and a microwave band.

Generally, an interrogator is fixed to a facility on the ground, and a transponder is attached to a mobile object such as a person, an object, a vehicle, an animal, etc., which is an object of individual identification. The interrogator is connected to a higher-level external processing device such as a computer, and is often subjected to transmission / reception control and individual identification processing. Further, many of the interrogator functions have a function of supplying power to the transponder in addition to the communication with the transponder, and others have a function of writing information to the transponder.

[0004] The device is also called a non-contact data carrier, the interrogator is also called a reader / writer or controller, and the transponder is also called an ID card or ID tag.

First, the basic operation of the conventional device using a long wave band or short wave band will be outlined with reference to FIG. Next, the basic operation of the conventional device using the microwave band will be described with reference to FIG.

FIG. 3 is a configuration diagram of the device using a long wave band or a short wave band. In the figure, reference numeral 1y denotes an interrogator.
Reference numerals 11, 13 to 15 denote 10 a control unit, 11 a data conversion unit, 13 a transmission unit, 131 a modulation amplification circuit housed in the transmission unit 13, 132 an oscillation circuit housed in the transmission unit 13,
Reference numeral 14 denotes a receiving unit, 141 denotes an amplification / demodulation circuit accommodated in the receiving unit 14, 15 denotes an antenna unit, and 15y denotes a long wave band to short wave band antenna element housed by the antenna unit 15.

FIG. 3 shows a transponder 2y. The transponders 2y are classified into 20 to 24 according to main functions, 20 is a data memory unit, 21 is a data conversion unit, 22 is a transmission unit,
21 is a modulation / amplification circuit accommodated in the transmission unit 22, 222 is an oscillation circuit accommodated in the transmission unit 22, 23 is a reception unit, 231 is an amplification / demodulation circuit accommodated in the reception unit 23, 24 is an antenna unit, and 24y is an antenna unit 24 1 shows a long-wave band to short-wave band antenna element to be accommodated. Reference numeral 3 in FIG. 3 denotes an external processing device connected to the device.

Referring to FIG. 3, the interrogator 1y will be described first, and then the transponder 2y will be described. The control unit 10 constituting the interrogator 1y sends an inquiry message of a parallel digital signal generated by a built-in microprocessor or a higher-order external processing device 3 to the data conversion unit 11.

[0009] The data conversion unit 11 converts the inquiry message of the parallel digital signal sent from the control unit 10 into a serial digital signal and transfers it to the transmission unit 13. The modulation and amplification circuit 131 of the transmission unit 13 modulates the serial digital signal from the data conversion unit 11 into a predetermined modulation method using the output of the oscillation circuit 132 as a carrier, amplifies the power, and feeds the power to the antenna unit 15.

The antenna section 15 generates an induced electromagnetic field in the antenna element 15y based on the output of the modulation amplification circuit 131, and transmits the generated electromagnetic field to the transponder 2y. Antenna element 15y
Is a loop antenna commonly used for transmission and reception, and FIG. 3 schematically shows this.

The response message of the transponder 2y captured by the antenna unit 15 induces a weak high-frequency current in the antenna element 15y, and is guided to the receiving unit 14 of the interrogator 1y. The amplification / demodulation circuit 141 of the reception unit 14 amplifies the reception current from the antenna unit 15, demodulates the current into a serial digital signal, and sends the serial digital signal to the data conversion unit 11.

The data converter 11 converts an input serial digital signal into a parallel digital signal and transfers it to the controller 10.

The control unit 10 processes the response message input to the data conversion unit 11 by a built-in microprocessor, and identifies the individual of the transponder 2y. The processing of the response message can be deciphered and processed by the control unit 10, or can be entrusted to the external processing device 3 connected to the interrogator 1y.

Next, the basic operation of the transponder 2y will be described. In FIG. 3, the antenna unit 24 of the transponder 2y has an interrogator 1y.
Received the question message issued by the antenna element 24y
To the receiving unit 23. The amplification / demodulation circuit 231 of the reception unit 23 amplifies a weak reception current from the antenna unit 24, demodulates the signal into a serial digital signal, and sends the serial digital signal to the data conversion unit 21.

[0015] The data conversion unit 21 that has received the demodulated inquiry message converts the inquiry message into a parallel digital signal and sends it to the data memory unit 20. Information and the like necessary for individual identification of the transponder 2y are written in the data memory unit 20 in advance.

The inquiry message from the data conversion unit 21 starts a memory read operation of the data memory unit 20 and specifies a predetermined read address. Data memory unit 2
0 sends the read memory output to the data conversion unit 21 as a parallel digital signal response message.

The data conversion unit 21 includes a data memory unit 20
The response message of the parallel digital signal input from
The signal is converted into a serial digital signal and transferred to the transmission unit 22.

The transmission section 22 composed of the modulation amplification circuit 221 and the oscillation circuit 222 modulates and amplifies the output of the oscillation circuit 222 with the response message from the data conversion section 21 by the modulation amplification circuit 221, and then sends it to the antenna section 24. I do.

The antenna element 24y of the antenna unit 24
The induction electromagnetic field generated by the output of the modulation amplification circuit 221 is emitted to the communication space. As the antenna element 24y, besides a loop antenna that is formed in accordance with the shape of the transponder 2y and is small in size and light in weight and easy to transmit and receive, there is also a type in which an antenna coil is wound around a core.

The basic operation of the device using the microwave band will be described with reference to FIG. The figure shows the configuration of the device in the microwave band, but there is no difference in basic operation from the device in the long wave band or short wave band except for the antenna section even in a different frequency band. Therefore, a 1z interrogator, a 2z transponder and 15
Except for the z and 24z antenna elements, the same reference numerals as in FIG.

In the device using the microwave band, since the wavelength of the electromagnetic wave is sufficiently shorter than the transmission distance between the interrogator 1z and the transponder 2z, the communication between the two uses a radiated electromagnetic field (radio wave) with the medium. It will be. Devices in the microwave band are susceptible to reflection from nearby conductors, and nearby devices can cause mutual interference.

To avoid this, an antenna having enhanced directivity is required. At the same time, in order to reduce the size and weight of the antenna sections 15 and 24, patch antennas formed by printed wiring are arranged on the antenna elements 15z and 24z in a plane. Array antennas are often used. The antenna element 15z of the interrogator 1z and the antenna element 24z of the responder 2z in FIG.
Schematically shows an array antenna.

[0023]

As described above, as an overview of the conventional device, the device is an application of wireless communication technology. The frequency to be used is selected according to the use of the device, is specified by the transmission distance between the interrogator and the transponder, and the individual device is operated.

For example, a vehicle approaching an area in the vicinity of tens of meters is automatically identified by the device using a microwave band, and a passenger in a vehicle within an area within 1 meter is automatically identified by the device using a long wave band. It is not advisable to install and operate interrogators individually for each frequency band. In addition, an unnecessary external wave arriving in the communication space may cause an error in identification.

The present invention has been made in order to solve the above-mentioned problem, and it is possible to avoid an individual identification error due to interference with an unnecessary extraneous wave and integrate a plurality of interrogators having different frequencies into one. The purpose of the present invention is to provide an RFID multi-purpose interrogator capable of responding to the above transponder.

[0026]

SUMMARY OF THE INVENTION An RFID multi-purpose interrogator according to the present invention is a control unit, a data conversion unit, a transmission / reception data switching unit, a transmission unit, and a reception unit in an RFID device which communicates via electromagnetic waves to perform individual identification. And a complex antenna unit as a main component, the control unit controls the operation of the interrogator, and converts the parallel digital signal interrogation message generated by the control unit into a serial digital signal in the data conversion unit. Converting, modulating a plurality of radio frequencies generated by the transmission unit via the transmission / reception data switching unit, transmitting the radio frequency to the communication space by the composite antenna unit, and transmitting a response message by the plurality of radio frequencies received by the composite antenna unit. , Demodulates to a serial digital signal at the receiving unit, passes through the transmission / reception data switching unit, enters the data conversion unit, converts it to a parallel digital signal, and the control unit Performing another, characterized by multiple communication with multiple transponders using a plurality of radio frequencies.

In multiplex communication with a plurality of transponders using a plurality of radio frequencies, a mode in which transmission is suspended and an external wave is intercepted, and a frequency in which the external wave is not intercepted in the mode in which the external wave is intercepted are simultaneously transmitted and received. And a mode in which a frequency in which the external wave is not intercepted in the mode in which the external wave is intercepted is sequentially switched and transmitted and received, and automatic external wave detection in a communication space and multiple communication with a plurality of transponders are provided. It is characterized by.

The composite antenna section of the RFID multi-purpose interrogator is characterized by a composite antenna in which a plurality of antenna elements shared for transmission and reception are accommodated in one antenna section.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows R using two frequency bands.
FIG. 2 illustrates a configuration diagram of an FID multi-purpose interrogator (hereinafter abbreviated as the interrogator), and also schematically illustrates communication between the interrogator, a conventional transponder, and the like. FIG. 2 schematically shows the transition of the transmission / reception mode according to the second aspect. In FIG. 1, parts corresponding to those in FIGS. 3 and 4 are denoted by the same reference numerals.

In FIG. 1, reference numeral 1a denotes the interrogator. The interrogator 1a classified according to its main functions includes 10 control units, 11 data conversion units, 12 transmission / reception data switching units,
13 transmitting sections, 14 receiving sections, 16 composite antenna sections,
And 17 power supply units.

The transmitting unit 13 includes a transmitting unit 13a for generating an electromagnetic wave in a long-wave band or a short-wave band, and a transmitting unit 13b for generating an electromagnetic wave in a microwave band. The transmitting unit 13a includes a modulation amplification circuit 13a1 and an oscillation circuit 13a2. The transmission unit 13b contains a modulation amplification circuit 13b1 and an oscillation circuit 13b2.

Similarly, the receiving section 14 comprises a receiving unit 14a for receiving electromagnetic waves in the long-wave band or short-wave band and a receiving unit 14b for receiving electromagnetic waves in the microwave band. The receiving unit 14a houses an amplification / demodulation circuit 14a1. , The receiving unit 14b houses an amplification / demodulation circuit 14b1.

The composite antenna section 16 is a composite antenna having a transmitting / receiving long-wave band or short-wave band antenna element 16a and a microwave band antenna element 16b. These antenna elements 16a and 16b are covered with a radome (not shown). Have been done.

2y and 2z are conventional transponders, 2y is a transponder in the long-wave band to short-wave band, and 2z is a transponder in the microwave band. These transponders 2y and 2z are the conventional transponders. It belongs and its explanation is omitted. Reference numeral 3 denotes an external processing device connected to the interrogator 1a.

First, a transmission / reception mode cycle showing transition of the transmission / reception mode which is a feature of the present invention will be described with reference to FIG. Next, with reference to FIG. 1, a transmission / reception operation with a transmission / reception mode cycle as a background will be described.

As shown in FIG. 2, the transmission / reception mode cycle starts from the setting routine of step 100 and proceeds to step 101.
3 shows the transition of the transmission / reception mode for processing the automatic detection of an extraneous wave in the communication space and the multiplex communication from the silent mode to the scramble mode in step 102 or the hopping mode in step 103.

When the interrogator 1a is started, the control unit 10 starts a setting routine (step 100). The setting routine selects either the transmission / reception mode of the scramble mode or the hopping mode, and sets the silent time and the contact time.

Selection of the transmission / reception mode is performed by setting a switch (not shown) of the control unit 10. The setting of the silent time, which is the duration of the silent mode, and the contact time, which is the duration of the scramble mode and the hopping mode, are performed by operating two switches (not shown) of the control unit 10. After this initialization, the transmission / reception mode cycle shifts to the silent mode.

In the silent mode (step 101),
In this mode, transmission of the inquiry message is paused to listen to an extraneous wave, and the arrival of an unnecessary extraneous wave that causes an error in individual identification is detected. The silent mode continues until the silent time set in the setting routine is reached. When the silent time ends, the transmission / reception mode cycle shifts to the scramble mode or the hopping mode.

Scramble mode (step 102)
Is a mode in which a plurality of frequencies in which a foreign wave is not intercepted in the silent mode are simultaneously transmitted and received. Interrogator 1a
Transmits a plurality of interrogation messages at the same time, receives response messages from the plurality of transponders 2y and 2z, and performs individual processing in parallel.

The scramble mode starts after the silent mode when the scramble mode is selected in the setting routine, and continues transmission / reception until a predetermined time is reached as a contact time.

The hopping mode (step 103)
This is a mode in which a frequency in which an external wave is not intercepted in the silent mode is sequentially switched to transmit and receive. The interrogator 1a transmits an interrogation message at a single frequency, receives a message from the transponder 2y or 2z according to the interrogation message, and sequentially processes individual identification for each transmission frequency.

In the hopping mode, when the hopping mode is selected in the setting routine, the hopping mode is started following the silent mode, and transmission / reception is continued until a predetermined time is reached as the contact time.

When the interrogator 1a is started, the microprocessor as the internal circuit of the control unit 10 and the built-in program advance the transmission / reception mode cycle of FIG. The setting routine (step 100) is started, the transmission / reception mode of the scramble mode or the hopping mode is selected, and when the silent time and the contact time are set, the mode shifts to the silent mode (step 101).

The control unit 10 instructs the two transmission units 13a and 13b of the transmission unit 13 to stop transmitting the inquiry message, instructs the reception unit 14 to receive an extraneous wave, and executes the silent mode. I do. Receiving unit 14
a and 14b transmit an interference warning to the control unit 10 when an external wave in the reception band is received.

The control unit 10 monitors the interference warning during the silent time. Thereafter, the transmission / reception mode cycle shifts from the silent mode to one of the scramble mode and the hopping mode.

In FIG. 2, when the transmission / reception mode cycle shifts to the scramble mode (step 102),
The control unit 10 instructs the transmission unit 13 to perform simultaneous transmission of a frequency without interference warning, and instructs the reception unit 14 to receive this frequency. For example, the receiving units 14a and 1
4b, the transmission unit 13
a and 13b transmit two frequencies simultaneously, and the receiving units 14a and 14b receive the two frequencies in parallel.

In FIG. 2, when the transmission / reception mode cycle shifts to the hopping mode (step 103), the control unit 10 instructs the transmission unit 13 to perform transmission by sequentially switching frequencies without interference warning, and instructs the reception unit 14. Instruct the reception corresponding thereto. For example, if there is no interference alarm in any of the receiving units 14a and 14b, the transmitting units 13a and 13b and the receiving units 14a and 14b perform transmission and reception on one frequency, and then perform transmission and reception on the other remaining frequency. .

In either the scramble mode (step 102) or the hopping mode (step 103), the frequency at which the interference warning occurs is stopped to intercept foreign waves. Even if there is only one transmittable frequency, the set transmission / reception mode is maintained. When the incoming foreign wave disappears, the reception unit releases the interference warning, and the control unit 10 starts transmission to the corresponding transmission unit. And the set transmission / reception operation is continued.

When the contact time, which is the communication time with the transponder, reaches a preset value, the control unit 10 switches the scramble mode (step 102) or the hopping mode (step 103) to the initial setting routine (step 100). One cycle of the return transmission / reception mode cycle is completed.

The next transmission / reception mode cycle starts automatically. If there is a change in the switching between the scramble mode and the hopping mode, and the setting of the silent time and the contact time, the setting is taken in the setting routine (step 100) and executed in the silent mode and the scramble mode or the hopping mode.

The transmission / reception operation of the interrogator 1a will be described with reference to FIG. 1 in the context of a transmission / reception mode cycle. When the antenna unit 16 captures a foreign wave in the silent mode, the high-frequency current induced in the antenna elements 16a and 16b is guided to the receiving unit 14.

The receiving units 14a and 14b of the receiving unit 14
Amplifies a weak reception current by the amplification and demodulation circuits 14a1 and 14b1, which are internal circuits, and tests the strength of the external wave. If the amplified output has reached a predetermined level, an interference warning is sent to the control unit 10 as a harmful external wave.

When the silent time ends, the control unit 10 shifts to either the scramble mode or the hopping mode, generates an inquiry message by the built-in microprocessor, and sends it to the data conversion unit 11. Further, the generation of the question message can be entrusted to the external processing device 3.

The data conversion unit 11 converts the parallel digital signal inquiry message sent from the control unit 10 into a serial digital signal, and transfers the serial digital signal to the transmission / reception data switching unit 12. Further, it converts a serial digital signal from the receiving unit 14 via the transmission / reception data switching unit 12 into a parallel digital signal and transfers it to the control unit 10.

The transmission / reception data switching unit 12 transmits the serial digital signal of the inquiry message transferred from the data conversion unit 11 to the transmission unit (the transmission units 13a and 13b or one of the transmission units 13b and 13b) of the transmission unit 13 instructed by the control unit 10. )
To send out. A receiving unit (both or one of the receiving units 14a and 14b) specified by the control unit 10
Is sent to the data converter 11.

The modulation and amplification circuit 13a1 of the transmission section 13 uses the output of the oscillation circuit 13a2 as a carrier wave for the data conversion section 11a1.
Is modulated into a predetermined modulation method, and thereafter, the power is amplified and supplied to the antenna unit 16.

Similarly, the modulation and amplification circuit 13b1 modulates the serial digital signal from the data conversion section 11 into a predetermined modulation method using the output of the oscillation circuit 13b2 as a carrier wave, and thereafter performs power amplification to supply power to the antenna section 16. I do.

The antenna element 16a of the antenna section 16
The induction electromagnetic field generated by the output of the modulation amplification circuit 13a1 is transmitted to the communication space. Similarly, the antenna element 16b
Transmits the radiated electromagnetic field generated by the output of the modulation amplification circuit 16b1 to the communication space.

The antenna section 16 of FIG. 1 schematically shows a structure of a composite antenna in which a phased array antenna as an antenna element 16b in a microwave band is arranged at the center of a loop antenna as an antenna element 16a in a long wave band. Is shown.

The response message generated by the transponder 2y induces a weak high-frequency current in the antenna element 16a of the antenna unit 16 and is guided to the corresponding receiving unit 14a of the receiving unit 14. An amplification / demodulation circuit 14a1, which is an internal circuit of the receiving unit 14a, amplifies the high-frequency current from the antenna unit 16 and demodulates it into a serial digital signal. The same applies to the response message issued by the transponder 2z, which is captured by the antenna element 16b of the antenna unit 16 and demodulated into a serial digital signal by the amplification / demodulation circuit 14b1.

The received signal demodulated to a serial digital signal is transmitted via a transmission / reception data switching unit 12 to a data conversion unit 11.
Is input to The data converter 11 converts a serial digital signal into a parallel digital signal and sends it to the controller 10. The control unit 10 processes the parallel digital signals input from the amplification and demodulation circuits 14a1 and 14b1, and performs individual identification of the transponders 2y and 2z. Further, the individual identification processing performed by the control unit 10 can be entrusted to the external processing device 3.

The power supply unit 17 converts an external commercial power supply into a predetermined DC voltage and supplies power to each unit of the interrogator 1a.
The power supply unit is based on the conventional technology, and the description is omitted.

The RFID multi-purpose interrogator according to the present invention, which monitors an external wave arriving in the communication space and performs multiple communication with a plurality of transponders using a plurality of frequencies unaffected by the external wave, is described above. It is as follows.

[0065]

According to the present invention, the transmission / reception function, which is a basic function of the RFID interrogator, is effectively developed. That is, the communication periodically pauses for a short period of time, monitors an external wave in the reception band during this pause, and interrupts communication with the transponder when an external wave exceeding a predetermined intensity is detected. According to the method, an error in individual identification due to interference with a foreign wave can be eliminated. Further, the transmission / reception function that handles a plurality of frequencies enables a single RFID interrogator to perform multiplex communication with transponders having different frequencies, thereby improving the processing capability of individual identification. In addition, a composite antenna in which a plurality of antenna elements are accommodated in one
The interrogator can be made small, and the area occupied by the installation and the construction cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a transition diagram of a transmission / reception mode according to an embodiment of the present invention.

FIG. 3 shows a conventional RF using a long wave band or a short wave band.
It is a block diagram of an ID device.

FIG. 4 is a conventional RFID using a microwave band.
It is a block diagram of an apparatus.

[Explanation of symbols]

1a RFID multi-purpose interrogator 1y Interrogator of RFID device using long wave band or short wave band 1z Interrogator of RFID device using microwave band 10 Control unit 11 Data conversion unit 12 Transmission / reception data switching unit 13 Transmission unit 131 Modulation amplification Circuit 132 Oscillation circuit 13a Long wave band to short wave band transmission unit 13a1 Modulation amplification circuit of long wave band to short wave band transmission unit 13a2 Transmission circuit of long wave band to short wave band transmission unit 13b Microwave band transmission unit 13b1 Microwave band transmission unit Modulation amplification circuit 13b2 Transmitting circuit of microwave band transmitting unit 14 Receiver 141 Amplifying and demodulating circuit 14a Receiving unit of long wave band or short wave band 14a1 Amplifying and demodulating circuit of long wave band or short wave band receiving unit 14b Receiving unit of microwave band 14b1 Microwave Band receiving unit Width demodulation circuit 15 Antenna part 15y Antenna element for long wave band or short wave band 15z Antenna element for microwave band 16 Composite antenna part 16a Antenna element for long wave band or short wave band 16b Antenna element for microwave band 17 Power supply part 2y Long wave band to short wave band transponder 2z Microwave band transponder 20 Data memory unit 21 Data conversion unit 22 Transmission unit 221 Modulation amplification circuit 222 Oscillation circuit 23 Receiving unit 231 Amplification demodulation circuit 24 Antenna unit 24y For long wave band or short wave band Antenna element 24z Antenna element for microwave band 3 External processing device

Claims (3)

[Claims] 1. An interrogator having a control unit, a data conversion unit, a transmission / reception data switching unit, a transmission unit, a reception unit, and a composite antenna unit in an RFID device that performs individual identification by communicating via an electromagnetic wave. The control unit controls the operation of the interrogator, converts the interrogation message of the parallel digital signal generated by the control unit into a serial digital signal by the data conversion unit, and generates the transmission message via the transmission / reception data switching unit. Modulates a plurality of radio frequencies, sends out the radio frequencies to the communication space by the composite antenna section, demodulates the response messages by the plurality of radio frequencies received by the composite antenna section into serial digital signals in the receiving section, and switches transmission / reception data. A plurality of transponders using a plurality of radio frequencies, which are input to a data conversion unit through a unit and converted into parallel digital signals, and perform individual identification of the transponders in a control unit. RFID multi-purpose interrogator characterized by multiple communications. 2. A multiplex communication with a plurality of transponders using a plurality of radio frequencies according to claim 1, wherein a mode of suspending transmission and intercepting an extraneous wave, and an extraneous wave in a mode of intercepting the extraneous wave are provided. A mode for simultaneously transmitting and receiving frequencies that are not intercepted, and a mode for sequentially transmitting and receiving frequencies that are not intercepted by the external waves in the mode for intercepting the external waves, and automatically detects external waves in the communication space. RF characterized by multiple communications with multiple transponders
ID multi-purpose interrogator. 3. The multi-purpose RFID interrogator according to claim 1, wherein the composite antenna unit includes a composite antenna in which a plurality of antenna elements shared for transmission and reception are accommodated in one antenna unit.