KR100812061B1 - Rfid antenna, rfid tag and rfid system - Google Patents

Abstract

An RFID(Radio Frequency IDentification) antenna, an RFID tag, and an RFID system are provided to increase the utilization of the RFID tag by performing communication in dual frequency bands by the RFID antenna. An RFID tag(100) includes an IC chip(101) and an RFID antenna(140). The RFID tag communicates with different readers in dual frequency bands. The RFID antenna includes first and second electric conductors(105,107) and first and second conductors(120,121) having an open slot structure on both surfaces of a supporter(110). The supporter is realized in a rectangular structure so as to irradiate an RF(Radio Frequency) signal. The IC chip is electrically connected between the first and second electric conductors. The first and second electric conductors supply a current fed by the IC chip at a feeding point to the conductors. A slot(130) is formed between the first and second conductors.

Description

Rfid antenna, rfid tag and rfid system {RFID antenna, RFID tag and RFID system}

1 is a block diagram showing a conventional radio frequency identification tag.

Figure 2 is a front perspective view showing an RFID tag according to the present invention.

3 is a rear perspective view of FIG. 2;

4A and 4B show an example of mounting an IC chip.

(A) (b) of FIG. 5 is a diagram showing an example of surface current according to power feeding in an RFID tag.

6 is a view showing the surface current according to the power supply in the RFID tag according to an embodiment of the present invention.

Figure 7 (a) (b) is a view showing the surface current and the radiation pattern by the first resonant frequency in the RFID tag according to an embodiment of the present invention.

8A and 8B are diagrams illustrating surface currents and their radiation patterns according to a second resonance frequency in an RFID tag according to an exemplary embodiment of the present invention.

9 is a view showing a first resonant frequency band in an RFID tag according to an embodiment of the present invention.

10 is a view showing a second resonance frequency band in an RFID tag according to an embodiment of the present invention.

11 is a view showing a change in the resonant frequency according to the change in length between the conductor and the slot in the RFID tag according to an embodiment of the present invention.

12 is a diagram illustrating an RFID system to which RFID is applied according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

100: RFID tag 101: IC chip

105,107 conductor 110 support

120121: conductor 140: antenna

200,300: Leader

The present invention relates to a radio frequency identification (RFID) antenna, an RFID tag, and an RFID system.

In general, radio frequency identification (RFID) is a technology for non-contact recognition or recording of information held by a tag using radio frequency, and recognizes and tracks a tagged object, the same person, or the like. , Technology that can be managed. Such an RFID system has a unique identification information and includes a tag (tag or transponder) attached to an object or animal, and a reader (reader or interrogator) for reading or recording the identification information of the tag.

1 is a diagram illustrating a conventional radio frequency identification tag.

Referring to FIG. 1, an RFID recognition tag 10 includes an IC chip 20 and an antenna 30. The IC chip 20 includes an RF transmission / reception circuit, a control logic and a memory, and an antenna 30. Transmit and receive radio frequency through.

The RFID tag 10 reflects a signal of a specific RF band transmitted from a reader (not shown) and modulates information including identification information in the reflected RF signal and transmits the information to the reader.

The antenna 30 used for the RFID tag 10 has a form of a dipole antenna printed on a film. That is, the characteristics of the antenna applied to the RFID tag 10 are designed in the form of a radiation pattern of the dipole antenna.

In addition, the existing RFID tag has been used separately for each frequency, there is a problem that can not use the RFID reader in the other reader. To this end, the development of a dual band RFID tag is required.

The present invention provides an RFID antenna and an RFID tag having the same.

The present invention provides an antenna resonating in a dual frequency band and an RFID tag having the same.

The present invention provides an RFID tag and an RFID system using the RFID tag having an antenna having a conductor and an open slot conductor on both sides of the support to communicate with different readers.

RFID antenna according to an embodiment of the present invention support; First and second conductors formed on the support for power feeding; First and second conductors formed for grounding under the support; And a slot formed between the first and second conductors.

In addition, the RFID tag according to an embodiment of the present invention, a conductor having a conductor and an open slot structure on both sides of the dielectric is formed, the RFID antenna operating in a dual resonant frequency band; And an IC chip electrically connected to a feed point of the conductor.

In addition, the RFID system according to an embodiment of the present invention, the RFID tag including a conductor having a conductor and an open slot on both sides of the dielectric, and an antenna that operates in a dual frequency band, and an IC chip connected to the feed point of the antenna; And first and second RFID readers respectively communicating through a dual frequency band of the RFID tag.

Hereinafter, with reference to the accompanying drawings as follows.

2 and 3 are front and rear perspective views of the RFID tag according to the present invention.

2 and 3, the RFID tag 100 includes an IC chip 101 and an RFID antenna 140, and may simultaneously communicate with different readers in a dual frequency band.

The RFID antenna 140 includes first and second conductors 120 and 121 having first and second conductors 105 and 107 and open slots 130 on both sides of the support 110.

The support 110 includes a dielectric substrate (eg FR-4) or an insulator (eg insulation film). In the case where the dielectric substrate is used, copper foils on both surfaces of the dielectric substrate may be etched to form a conductor shape having a desired conductor shape and an open slot structure. The present invention will be described using a support as a dielectric for convenience of description. At this time, the capacitive reactance of the RFID antenna may be changed according to the dielectric constant of the dielectric (for example, 3.5 to 4.7).

In addition, the insulating film is, for example, polypropylene with PET film, polyimide (PI), polyethylene naphtharate (PEN), polyvinyl chloride (PVC), paper, acetate, polyester, polyethylene, polypropylene, calcium carbonate Acrylonitrile butadiene styrene (ABS) or plastics. The selection of the material of such a film member may be made of one or two or more of the above materials, or a combination of the above materials. Conductors and conductors can be printed and formed on both sides of the insulating film, respectively.

In addition, the support 110 may be implemented in a rectangular structure, such as square or rectangular for the radiation of the RF signal.

The first and second conductors 105 and 107 are formed on both sides of the feed point at a predetermined width (about 0.8 to 1.2 mm) along the feed direction on the support 110, and the first and second conductors ( An IC chip is electrically connected between 105 and 107.

In addition, the first and second conductors 105 and 107 are lines through which electric current flows, and may be formed as micro strip lines along the feeding direction on the support 110, and may be formed by the IC chip 101 at the feeding point. It delivers the electric current supplied to the conductors (120, 121).

The first and second conductors 120 and 121 are formed in an asymmetrical size under the support 110, and a slot 130 is formed between the first and second conductors 120 and 121. Here, the formation positions of the conductors and the conductors formed on both sides of the support 110 may be changed.

The first and second conductors 120 and 121 are formed on the entire bottom surface of the support 110 and serve as a ground of the RFID antenna 140. Here, the conductors 105 and 107 and the conductors 120 and 121 operate in an open circuit stub structure.

In addition, the first and second conductors 120 and 121 are formed in an asymmetrical structure with respect to the slot 130 at the bottom of the support, and the first conductor 120 is formed to have a length L1 larger than that of the second conductor 121. Can be formed and vice versa.

The slot 130 formed between the first and second conductors 120 and 121 is formed perpendicular to the feeding directions of the first and second conductors 105 and 107. That is, when the first and second conductors 105 and 107 are formed in the left / right direction (or the x-axis direction) on the support, the slot 130 is positioned between the first and second conductors under the support. It is formed in the rear direction (or y-axis direction), and both ends are formed in an open structure.

In addition, the slot 130 may be formed at one side or the other side under the support, centering on the IC chip 101. That is, since the IC chip 101 operates without polarity, the feed current flows in both directions along the conductors 105 and 107 and the second conductors 120 and 121, so that the position of the slot 130 is also the first conductor 120. It may be formed at the front or end portion of the.

The width of the slot 130 is determined according to the capacitance by the slot 130 and the characteristic impedance of the conductors 105 and 107, and the position of the slot 130 is determined by the length L1 of the first conductor 120. It may be changed according to the resonance position of the first frequency determined accordingly.

Here, the RFID antenna 140 may be manufactured in various sizes (eg, λ / 4) according to the application to which the RFID tag 100 is applied. For example, the support 110 may have a predetermined size (A * B). = 8 * 8 cm), the support thickness t is about 1 mm, and the conductors 105 and 107 formed on the support may be formed to have a width of 1 mm and a thickness of 0.5 mm. In this case, the widths, thicknesses, and feeding lengths of the first and second conductors 105 and 107 may be the same or different.

The IC chip 101 may have a built-in RF transmission / reception circuit, a control logic, a memory, and the like, and transmits / receives an RF frequency in a dual frequency band through the RFID antenna 140. The RF signal of the IC chip 101 flows through the conductors 105 and 107 and the conductors 120 and 121, and the conductors 105 and 107 provide the received RF signal to the IC chip 101. At this time, the RF frequency is emitted little by little in the form of an electric field (E Field), a magnetic field (H Field) in the form of electromagnetic waves on the lines of the conductors (105, 107). Accordingly, a coupling (eg, inductive coupling) phenomenon in which signal energy of the conductors 105 and 107 flows into the conductors 120 and 121 is generated. The IC chip 101 is electrically connected between the first and second conductors 105 and 107, and may have no directivity with respect to the electrical polarity (+,-) (+,-).

4 is a diagram illustrating an example of mounting an IC chip in an RFID tag according to an embodiment of the present invention.

Referring to FIG. 4, the ICs 101 are mounted to feed the conductors 105 and 107 of the IC chip 101, and the IC chips 101 are electrically conductive using the conductive pads 102 as shown in (a). It is mounted on the lead 125 or is electrically connected to the conductors 105 and 107 using the wire 103 of the IC chip 101 as shown in (b). As such, the electrical connection between the IC chip 101 and the conductors 105 and 107 can be variously changed by flip chip bonding or wire bonding, depending on the application.

5A and 5B are diagrams illustrating an example of an operation of an RFID tag according to an exemplary embodiment of the present invention.

Referring to FIG. 5, the currents I11 and I12 output from the IC chip 101 flow through the first and second conductors 120 and 121 along the first and second conductors, thereby providing a first frequency f1 band. Resonance occurs. In addition, when current flows along the first and second conductors 120 and 121, coupling occurs between the first and second conductors 120 and 121, so that a part I13 of the feed current flows along the slot 130. The resonance occurs in the second frequency f2 band.

The RFID tag 100 generates resonance in a first frequency f1 band between the conductors 105 and 107 and the conductors 120 and 121 by the RF signal supplied from the IC chip 101, and the slot between the plurality of conductors. At 130, resonance occurs in the second frequency f2 band. That is, the RFID antenna 140 may induce double resonance through offset feeding of the slot 130 using an open circuit stub. In this case, a ratio f1 / f2 of the resonance frequency may be determined according to the position and width of the slot 130 in the conductors 120 and 121. Here, the first frequency f1 is lower than the second frequency f2.

Here, the first frequency f1 band covers the 850 to 1015 MHz band and satisfies all the European RFID (865 to 868 MHz), North American RFID (902 to 928 MHz), and Korean RFID (908.5 to 915 MHz) frequency bands. The second resonant frequency (f2) band is 2.319 ~ 2.516GHz to satisfy all of the active (RF) RFID frequency band. That is, the RFID tag 100 may provide a dual band RFID device by performing resonance in the first frequency band of the UHF band and the second frequency band of the microwave band.

FIG. 6 is a diagram illustrating surface currents in a conductor and a slot according to a power supply in an RFID tag according to an exemplary embodiment of the present invention. As shown in the drawing, the feed currents I11 and I12 flow in both directions along the conductor, and coupling occurs in the slot 130 to cause some feed current I13 to flow along the slot 130. As a result, resonance occurs in the dual frequency band.

7A and 7B illustrate a surface current distribution and a radiation pattern according to a first resonance frequency in an RFID tag according to an embodiment of the present invention, and FIGS. 8A and 8B illustrate an embodiment of the present invention. Figure 2 shows the surface current distribution and its radiation pattern by the second resonant frequency in the RFID tag according to the present invention. Here, the radiation pattern of the RFID tag is a value measured while the reader is sequentially moved from 0 to 90 degrees in the angle (θ, Φ) in each axis direction.

9 and 10 are diagrams illustrating bandwidths BW1 and BW2 of a first resonance frequency and a second resonance frequency of an RFID tag according to an exemplary embodiment of the present invention, respectively. At this time, the standing wave ratio was 2.0, and the gain (dB) was measured at -10 dB in the S parameter (S1.1).

As shown in FIG. 9, the first resonance frequency is resonance at 0.85041 MHz to 1.0154 GHz, and the first bandwidth BW1 at that time is obtained as 0.16497 GHz, as shown in FIG. 10. Resonance occurs at 2.3194 to 2.5359 GHz, and the second bandwidth BW2 at this time is found to be 0.21649 GHz.

FIG. 11 is a frequency and gain distribution diagram (as seen from S11) according to the length (L1 of FIG. 3) of the first conductor formed under the support in the RFID tag according to the present invention. As shown in the drawing, the length L1 of the first conductor is increased to 10 mm, 20 mm, 30 mm, 40 mm, and 50 mm, and thus the length resonating in the dual frequency band can be found. At this time, the length measurement interval of the first conductor may be changed to 5 mm or the like.

That is, the farther the position of the slot 130 shown in FIGS. 2 and 3 toward the end of the first conductor 120, the lower the resonant frequency, which becomes longer as the length of the first conductor 120 becomes longer. ) Is a phenomenon that occurs as the wavelength of the energy transmitted to the slot 130 by the forced condition from the longer. On the other hand, the closer to the center of the slot 130 in the first conductor (120, 121), the single resonance is dominant, and the greater the degree of offset away from the center of the slot 130, the greater the degree of double resonance and the ratio of the two frequencies increases.

12 is a block diagram showing an RFID system according to the present invention. As shown in FIG. 12, the RFID tag 100 and the reader 200 and 300 simultaneously communicate in bands of different short-range radio frequencies f1 and f2. Here, the different wireless communication bands are, for example, bands of 860 to 1015 MHz and 2.319 to 2.536, and can simultaneously communicate with the reader in two bands.

Here, the RFID tag provides identification information recorded through communication with the first and second readers 200 and 300, and is passively operated by receiving energy from a radio signal of a reader without an active or internal power source including a battery. Can be. The RFID tag of the present invention may also function as an RFID reader.

 Although the present invention has been described above with reference to the embodiments, these are only examples and are not intended to limit the present invention, and those skilled in the art to which the present invention pertains may have an abnormality within the scope not departing from the essential characteristics of the present invention. It will be appreciated that various modifications and applications are not illustrated.

For example, each component shown in detail in the embodiment of the present invention may be modified. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

By communicating in a dual frequency band by the RFID antenna according to the present invention, it is possible to increase the usability of the RFID tag.

In addition, it is possible to simultaneously communicate with different readers through a single RFID tag, there is an effect that does not have to have a different RFID tag.

Claims (25)

Support; First and second conductors formed on the support for power feeding; First and second conductors formed for grounding under the support; RFID slot comprising a slot formed between the first and second conductors. The method of claim 1, And the slots are formed perpendicular to the feeding directions of the first and second conductors. The method of claim 1, And the first and second conductors are asymmetrically sized. The method according to claim 1 or 3, The slot is an RFID antenna having a structure in which both ends are open between the first and second conductors. The method of claim 1, The support is an RFID antenna made of either a dielectric or an insulating member. An RFID antenna comprising a dielectric, a conductor formed over the dielectric, and a conductor having an open slot structure formed below the dielectric, the RFID antenna operating in a dual resonant frequency band; And an IC chip electrically connected to a feed point of the conductor. The method of claim 6, And the conductor includes first and second conductors electrically connected to an IC chip over a dielectric. The method of claim 6, And wherein the conductor comprises first and second conductors formed below ground in the dielectric and having open slots therebetween. The method of claim 8, And the first and second conductors are formed in an asymmetric size with respect to the slot. The method of claim 6, The slot is an RFID tag formed on one side or the other side of the dielectric based on the feeding point. The method of claim 6, The slot is an RFID tag formed in a direction perpendicular to the feed direction. The method of claim 6, RFID tag resonates in the first frequency band by the conductor and the conductor according to the feeding of the IC chip, and resonates in the second frequency band by the slot and the open slot therebetween. The method of claim 12, The first frequency band is 850 ~ 1015MHz, The second frequency band is RFID tag, characterized in that 2.319 ~ 2.536GHz. The method of claim 6, The dielectric tag is formed of a square or rectangular RFID. The method of claim 6, The dielectric is an RFID tag formed to a thickness of 1mm. The method of claim 6, At least one of the conductor or conductor is formed to a thickness of 0.5mm. The method of claim 6, The conductor is an RFID tag formed to a width of 1mm. The method of claim 6, And said dielectric has at least one side quarter wavelength. An RFID tag comprising a dielectric, a conductor formed on the dielectric, and a conductor having an open slot structure formed below the dielectric, the antenna operating in a dual resonant frequency band, and an IC chip connected to a feeding point of the antenna; And a first and a second RFID reader each communicating over a dual frequency band of the RFID tag. The method of claim 19, And the conductor is separated into first and second conductors in an asymmetrical size relative to the slot. The method of claim 19, And the slot is formed at one side or the other side under the dielectric with respect to the feeding point. The method of claim 19, And the slot is formed in a direction perpendicular to the feeding direction. The method of claim 19, RFID system resonates in a first frequency band by the conductor and the conductor according to the feeding of the IC chip, and resonates in the second frequency band by the open slot structure therebetween. The method of claim 23, wherein The first frequency band is 850 ~ 1015MHz, The second frequency band is 2.319 ~ 2.536GHz RFID system, characterized in that. The method of claim 19, And the RFID tag is active or passive.

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