KR101063944B1 - A UHF RFID metal tag for long reading range using a cavity structure - Google Patents

Abstract

The present invention relates to a UHF RFID metal tag for long-range recognition using a cavity structure, wherein the dielectric body 20 and the dielectric film 20 formed on the upper surface of the cylindrical body 10 having a hollow portion inside the cylinder 10 are formed. A tag antenna formed of a metal film 30 formed at a central portion away from an edge of the c), a patterning part 40 in which the metal film 30 is patterned in a loop shape, and mounted at one end of the patterning part 40. A metal tag structure (A) made of a UHF RFID chip 50; Since the metal tag structure (A) is composed of a tag casing (B) embedded therein employs a cavity structure in the tag to increase the gain of the antenna can be recognized at a long distance, so the reader system does not require many readers It can reduce not only installation and maintenance costs, but also logistics costs, and can be recognized from a long distance, thereby improving reliability in managing metal equipment and equipment, and reducing management costs by managing metal materials and location tracking in real time. It is a useful invention with particular advantages.

Cavity Structure, Metal Tag, RFID, Reader, Logistics Management.

Description

AHH RFID metal tag for long reading range using a cavity structure

The present invention relates to a metal tag, and more particularly, a UHF RFID for long-range recognition using a cavity structure that can be recognized even at a long distance by employing a cavity structure in a tag to increase the gain of the antenna. It relates to a metal tag.

Ubiquitous refers to an information and communication environment in which a user can freely access a network regardless of a location without being aware of a network or a computer. For ubiquitous, Radio Frequency Identification (RFID) systems operate on a wide range of networks, such as the World Wide Web. RFID is a technology that aims to recognize a physical object and find out information about the object. The identification code assigned to each object is called a tag code and is encoded in an RFID tag. These codes are the basis for using information services for objects.

In general, RFID is one of Automatic Data Collection such as bar code. It consists of a transponder, a transceiver that receives signals from the outside and automatically returns signals, and a reader / controller that sends or reads these signals.

Compared to a general barcode system, the transponder is a barcode and the reader acts as a scanner. As a barcode scanner scans and reads a barcode label, an RF reader uses radio waves to transmit data. To read.

Barcodes are restricted from use because they can tear or contaminate labels, but transponders are semi-permanent in microchip form and are independent of the environment. Dirt or rain can quickly reduce the recognition rate of barcodes, but RFID is less intrusive to the environment.

Because of the use of radio frequency (RF), transponders and readers react in a non-contact manner, resulting in fast data reading. In addition, it can transmit and receive a large amount of information compared to bar codes.

It is used by many people because of its application to transportation cards, and is widely used in access control systems for company employees, residents, and visitors as it is applied to access control systems. In addition, it is applied to efficient logistics management, inventory management, and anti-theft field, which has significant productivity improvement and cost reduction effect, and has the advantage of identifying purchase, logistics, and sales in real time in connection with enterprise resource planning (ERP) system. .

Most of the appearance of the RFID tag currently used is plastic card, which can only be printed with offset or silk on the front and back. The plastic card type can be applied to clothing, fashion and logistics distribution products. Inappropriate. Because it is not suitable for hanging on products, and the price of RFID tags is high, printing images of brand products with short cycles is difficult to use for other brands of products. There are cumbersome problems to do.

1 is a conceptual diagram of a general RFID network, in which an RFID tag 1 attached to an object, a reader 2 for reading an RFID tag, and user information read through the reader 2 are sent to the server 4. It comprises a network (3) for providing, and a server (4) for receiving user information of the RFID tag (1) received through the network (3), searching and comparing with previously stored information. The reader 2 is naturally a concept including a reader antenna (not shown).

2 is a diagram illustrating a conventional RFID tag structure, in which a general RFID tag 1 is a chip 5 for storing information (data) of an object, and is connected to the chip 5 to transmit and receive data to and from a reader. And an antenna 6 for transmitting electromagnetic waves to or from the space. The RFID tag has various use frequency bands such as 125/134 Hz, 13.56 MHz, 433 MHz, 900 MHz, and the like, and the recognition distance from the reader may vary depending on the antenna type.

For example, in the case of an RFID tag having a 13.56 MHz frequency band, a recognition distance with a reader can be largely divided into a short distance of 10 cm or less, a medium distance of about 30-40 cm, and a long distance of 40 cm or more. However, the RFID tag having a 13.56 MHz frequency band has a problem in that it can be applied only to a very limited field because the recognition distance from the reader is very short.

In addition, an active metal tag used at 433MHz as a long-range metal tag has been developed and used. However, the active metal tag has a recognition distance of 100m or more, but the price of the tag is not only expensive than the general passive tag, but also requires the use of its own power source. There is a costly disadvantage.

Accordingly, the present invention has been made to solve various problems caused by the above-described conventional tag, and an object of the present invention is to recognize the tag at a long distance by increasing the gain of the antenna by employing a cavity structure in the tag. Since it does not require many readers, it is provided to metal tag for long distance recognition using cavity structure that can reduce not only system installation and maintenance cost but also logistics cost.

Another object of the present invention is to provide a metal tag for long-range recognition using a cavity structure that can be recognized at a long distance by increasing the gain of the antenna by employing a cavity structure in the tag to increase the reliability in the management of metal equipment and equipment. have.

Another object of the present invention is to employ a cavity structure in the tag to increase the gain of the antenna can be recognized from a long distance, and to manage the metal material and location tracking in real time, and to reduce the cost of the cavity structure To provide a long-term recognition metal tag used.

Long-range recognition metal tag using the cavity structure of the present invention for achieving the above object is a dielectric body 20 and the dielectric film formed on the upper surface of the cylindrical body 10 and the cylindrical body 10 forming a hollow portion ( A tag antenna formed of a metal film 30 formed at a central portion away from an edge of 20, a patterned portion 40 in which the metal film 30 is patterned in a loop shape, and at one end of the patterned portion 40. A metal tag structure A comprising a chip 50 to be mounted; The metal tag structure (A) is characterized in that it is composed of a tag casing (B) embedded therein.

The present invention can be recognized at a long distance by increasing the gain of the antenna by employing a cavity structure in the tag, so that many readers are not required in the reader system, thereby reducing the installation and maintenance costs as well as the logistics cost. It can be recognized at a long distance, so it can increase reliability in the management of metal equipment and equipment, and there is a special advantage to reduce the management cost by enabling the management of metal materials and location tracking in real time.

Hereinafter, the metal tag for long-range recognition using the cavity structure of the present invention will be described in detail with the accompanying drawings and preferred embodiments.

3 is a trial of a long distance recognition metal tag structure using the present invention cavity structure,

4 is a plan view of a metal tag structure for long distance recognition using the cavity structure of the present invention;

5 is a plan view of a metal tag structure for long distance recognition using the cavity structure of the present invention;

6 is a perspective view of a tag casing according to the present invention, Figure 7 is a view showing a state in which the metal tag structure is built in the tag casing according to the present invention,

8 is a graph showing a reflection coefficient of a metal tag structure according to Experimental Example 1 of the present invention;

9A and 9B are graphs showing measured impedances with and without a metal tag structure A according to Experimental Example 1 of the present invention on a metal;

10A and 10B are diagrams showing the gain of the measured tag antenna when there is no metal plate on the lower surface of the metal tag structure A according to Experimental Example 1 of the present invention;

11A and 11B are diagrams showing the gain of the measured tag antenna when the metal plate is located on the lower surface of the metal tag structure A according to Experimental Example 1 of the present invention;

12 is a graph showing a reflection coefficient of a metal tag structure according to Experimental Example 2 of the present invention;

13A and 13B are graphs showing measured impedances with and without a metal tag structure A according to Experimental Example 2 of the present invention on a metal;

14A and 14B are diagrams showing the gain of the measured tag antenna when there is no metal plate on the bottom surface of the metal tag structure A according to Experimental Example 2 of the present invention;

15A and 15B are diagrams showing the gain of the measured tag antenna when the metal plate is located on the bottom surface of the metal tag structure A according to Experimental Example 2 of the present invention;

16A is a photograph of a metal tag structure A prepared according to Example 1 of the present invention;

Figure 16b is a photograph of the casing state of the metal tag structure (A) produced according to Example 1 of the present invention,

17A is a photograph of a metal tag structure A prepared according to Example 2 of the present invention;

Figure 17b is a photograph of the casing state of the metal tag structure (A) produced in accordance with Example 2 of the present invention,

18A is a graph showing measured recognition distances of Squiggle2 tags of Examples 1 and 2 of the present invention in a free space without metal;

18B is a graph illustrating measured recognition distances of Embodiments 1 and 2 tags of the present invention with metal attached to a lower surface of a metal tag;

19 is a graph showing the results of sensitivity measurement of the metal tag according to the present invention.

The metal tag for long-range recognition using the cavity structure of the present invention has a central portion spaced apart from an edge of the dielectric layer 20 and the dielectric layer 20 formed on the upper surface of the cylindrical body 10 having a hollow portion inside. A tag antenna formed of a metal film 30 formed on the metal film 30, a patterning part 40 having the metal film 30 patterned in a loop shape, and a chip 50 mounted at one end of the patterning part 40. A metal tag structure (A) formed; It consists of the tag casing B in which the said metal tag structure A is built.

The cylinder 10 is a metal having a dielectric film 20 formed on an upper surface thereof and forming a hollow portion therein, and the metal film 30 is formed on the dielectric film 20 by any one of printing, silk screen, and etching methods. ), A cylindrical body 10, a dielectric film 20, and a metal film 30 form a tag antenna.

The patterning part 40 is a portion in which the metal film 30 is removed and the dielectric film 20 is patterned in the form of a "T" shaped closed loop. At one end, the chip 50 is mounted in a die bonding method or a strap method. It is.

The tag casing (B) is formed of ABS, polyester (PE), or polycarbonate (PC), or a mixture of at least two or more, or a non-conductive material that can protect all non-conductive plastic materials or circuits. It is made of a material, the body 61 having an opening in one side and the opening side both ends extending horizontally so as to embed the metal tag structure (A), the fastening portion 62 integrally with the body 61 And; Consists of a fastening hole 63 formed through the central portion of the fastening portion 62.

Experimental Example

As an embodiment of the present invention, a metal tag for long-range recognition using a cavity structure was designed as follows and the reflection coefficient and gain of the metal tag were measured through simulation.

The simulation tool is designed using CST Microstudio 2008. The chip impedance is designed using the impedance of Alien Higgs strap, and the center frequency of the metal tag is 910MHz.

Dielectric constant (ε) of 4.6 FR4 is used as the dielectric film 20 having the pattern of the metal tag structure (A), and styrofoam having a dielectric constant (ε) of 1.01 is used as the cylinder 10 to fix the height of the cavity. did.

The height of the cylindrical body 10 was adjusted in the state which fixed the thickness of the dielectric film 20 at 2 mm.

Starting the design of the cavity, that is, the hollow part inside the cylinder 10 at 0.25λ (82 mm), perform impedance matching, and reduce the overall height of the metal tag structure A by lowering the cavity height. Two efficient metal tags were designed.

One of the produced metal tags is a metal tag (Experimental Example 1) having a height of 0.003λ (10 mm), and the other is a metal tag (Experimental Example 2) having a height of 0.091λ (30 mm).

Experimental Example  One

In Experimental Example 1, the measured reflection coefficients of the metal tag structure A on the metal and the absence of the metal tag structure A were compared in FIG. 8, and the measured impedances were shown in FIGS. 9A and 9B, respectively. .

As shown in FIG. 8, when the metal tag structure A is on the metal at 904 MHz, the reflection coefficient is -13.2 dB, and the reflection coefficient is -10 dB in free space where the metal tag structure A is not on the metal. It can be seen that the performance of the tag antenna is better when the metal tag structure (A) is on the metal.

9A and 9B, respectively, the impedance is calculated as 23.16 + j132Ω in free space where the metal tag structure A is not on the metal, and the power transmission coefficient is 0.9, and the metal tag structure A is on the metal phase. The power transfer coefficient calculated as 18.76 + j132.99Ω is 0.95, and it can be seen that the metal tag structure (A) is better matched with the metal.

The above equation is obtained from the following power transmission coefficient calculation formula.

τ: power transfer coefficient (0≤τ≤1)

Za: Tag antenna impedance (Za = Ra + jXa)

Zc: chip impedance (Zc = Rc + jXc)

10A, 10B, 11A, and 11B are compared with the measured tag antenna gains in the case where there is no metal plate on the lower surface of the metal tag structure A. FIG.

10A and 10B are tag antenna gains when there is no metal plate on the bottom surface of the metal tag structure A, and FIGS. 11A and 11B are tag antenna gains when there is a metal plate on the back surface of the metal tag structure A. FIG.

As shown in FIGS. 10A and 10B, the tag antenna gain was 4.452 dB, the radiation efficiency was 67%, and the half power beamwidth was 132.4 ° in the free space without the metal plate on the lower surface of the metal tag structure A. FIG. On the other hand, as shown in FIGS. 11A and 11B, when a metal plate is present on the bottom surface of the metal tag structure A, the tag antenna gain is 5.311 dB, and the tag antenna gain is 0.859 dB higher than that without the metal plate. Was 60.5%, 7% lower than without the plate, and the half-power beamwidth was 99.5 °, 32.9 ° narrower than without the plate. Therefore, it can be seen that the tag antenna gain is higher when the metal plate is present on the lower surface of the metal tag structure A having a narrow beam width.

When the recognition distance is calculated using the Friis transfer equation, the recognition distance is 13.24 m in free space without a metal plate on the lower surface of the metal tag structure A, and 15.05 m with a metal plate on the lower surface of the metal tag structure A. Came out. As described above, in the state where the metal plate is located on the lower surface of the metal tag structure A, the recognition distance was found to be about 2m more than the free space without the metal plate.

Experimental Example 2

In Experimental Example 2, the measured reflection coefficients of the metal tag structure A and the metal tag structures A and 3 in the above Experimental Example were compared, and the measured impedances were shown in FIGS. 13A and 13B, respectively. .

As shown in FIG. 12, when the metal tag structure A is on the metal at 918 MHz, the reflection coefficient is -8.53 dB, and the reflection coefficient is -8.17 in the free space in which the metal tag structure A is not on the metal. In dB, there was no significant difference in the reflection coefficient, so the performance of the tag antenna was not different between the metal tag structure A and the metal.

In addition, the impedance is shown as shown in Figs. 13A and 13B, respectively, and the power transfer coefficient calculated as 26.3 + j128.96Ω in free space where the metal tag structure A is not on the metal is 0.85, and the metal tag structure A is The power transfer coefficient calculated as 25.16 + j128.59Ω for the metal phase is 0.86, which shows that the metal tag structure A is better matched with the metal phase.

In addition, the measured tag antenna gains in the case where there is no metal plate and under the metal tag structure A are compared and shown in FIGS. 14A, 14B, 15A, and 15B, respectively.

14A and 14B are tag antenna gains when there is no metal plate on the lower surface of the metal tag structure A, and FIGS. 15A and 15B are tag antenna gains when there is a metal plate under the metal tag structure A. FIG.

As shown in FIGS. 14A and 14B, the tag antenna gain was 5.45 dB, the radiation efficiency was 83%, and the half power beamwidth was 128 ° in the free space without the metal plate under the metal tag structure A. FIG. Meanwhile, as shown in FIGS. 15A and 15B, when the metal plate is under the metal tag structure A, the gain of the tag antenna 40 is 5.932, indicating that the tag antenna gain is 0.5 dB higher than that without the metal plate. The efficiency was 80%, 3% lower than without the plate, and the half-power beamwidth was 108.2 °, which was 19.8 ° narrower than without the plate. Therefore, it can be seen that the tag antenna gain is higher when the metal plate is present on the lower surface of the metal tag structure A having a narrow beam width.

When the recognition distance was calculated using the Friis transfer equation, the recognition distance was about 15 m in the free space without the metal plate and the metal plate on the lower surface of the metal tag structure (A).

Next, in consideration of the results obtained through the above experimental example, a metal tag for long-range recognition using a cavity structure was actually manufactured as in the following example, and the recognition distance and sensitivity of the manufactured metal tag were measured.

In order to form a cavity structure, the inside of the cylinder 10 was made of styrofoam so as to form a hollow portion, and the outside of the cylinder 10 and the dielectric film 20 was covered with copper tape.

FR4 having a dielectric constant? Of 4.6 is used as the dielectric film 20, and the Alien Higgs strap is bonded with silver paste using the metal film 30 to form a patterning portion 40 having a 0.2 μm tag pattern, and the chip 50 ) With a strap, covered with silicone to prevent the strap from peeling off.

One of the metal tags thus produced produced a metal tag structure (A).

Example 1

A metal tag having a size of 176 mm x 52 mm x 12 mm was produced in the same manner as described above. The produced metal tag structure A is as shown in Fig. 16A, and the metal tag structure A is cased with the tag casing B as shown in Fig. 16B.

Example 2

A metal tag having a size of 176 mm x 61 mm 31 mm was manufactured in the same manner as described above. The manufactured metal tag structure A is as shown in FIG. 17, and the metal tag structure A was cased with the tag casing B as shown in FIG.

The recognition distance and sensitivity were measured in the state of attaching the metal tags manufactured in Examples 1 and 2 to the free space and the metal, and compared with the general commercial tag Alien Squiggle2.

The recognition distance was measured using Alien's ALR-9800 with 1W reader, and the antenna of the reader was Alien's ALR-9610 with 6dBi linear polarization, and 10m chamber of Songdo u-IT Cluster Support Center. Although the recognition distance was measured in the radio wave reflection chamber, the recognition was measured at 10 m or more and the power of the reader system was reduced, and the results are shown in FIGS. 18A and 18B.

FIG. 18A is a graph showing measured recognition distances of Squiggle2 tags of Examples 1 and 2 of the present invention in a free space without metal, and FIG. 18B is a diagram showing the implementation of the present invention with metal attached to the bottom surface of a metal tag. Example 1 and 2 are graphs showing the measured recognition distances of tags.

In FIG. 18A, the result of measuring the power of the reader by 0.5 W (-3 dB) is also shown in the case of the second embodiment of the present invention. The recognition calculated by using the Friis transmission equation is shown in FIG. 18A. The distance was 8m, Example 2 was 11m, Example 2 was Squiggle2 of 5.5m Alien's Squiggle2 was found to be recognized in the free space without metal in the case of Example 2 of the present invention 10m or more 11m.

In the case of attaching a metal on the bottom surface of the metal tag, Example 1 of the present invention showed a recognition distance of 10 m or more, thereby reducing the power of the reader to 0.5 W (-3 dB) and measuring the power of the reader to 0.5 W. Even if the measurement was reduced to (-3dB), the recognition distance was more than 10m and the power of the reader was further reduced to 0.25W (-6B), and the result is shown in FIG. 18B.

When the recognition distance of the metal tag shown in FIG. 18B was calculated using the Friis transmission equation, it was confirmed that Example 1 was recognized at 11m and Example 2 at 15m.

As such, when the metal tags of Examples 1 and 2 of the present invention were attached to the metal plate, the recognition distance of the metal tags was increased by about 2 to 4 m or more than when the metal plate was not attached, and when the metal plate was attached, the embodiment of the present invention Both metal tags of 1 and 2 could be confirmed that can be recognized at more than 10m.

The sensitivity was measured in a 10m chamber (non-radio reflecting chamber) of the Songdo u-IT Cluster Support Center using a 2600A tester manufactured by TESCOM, and the results are shown in FIG. 19.

As shown in FIG. 19, the sensitivity of Example 1 of the present invention was confirmed to be maintained at -10 dB from 890 MHz regardless of whether metal was attached or not, and the sensitivity of Example 2 was -10 dB or less when attached to metal. This widening was confirmed, and the two metal tags of Examples 1 and 2 were found to be not significantly changed sensitivity regardless of the metal attached.

In Table 1 summarizes the recognition distance of the metal tag measured in the above embodiment is shown in Table 1.

Measured recognition distance by tag            Type of tag  Recognition distance of measured tag      Remarks Alien Squiggle2   Free space          5.5m Invention
(Example 1)   Free space          8m  Attach to metal          11m Size of metal:
320mm × 320mm Invention
(Example 2)   Free space          11m  Attach to metal          14m Size of metal:
320mm × 320mm

It can be seen from Table 1 that the metal tag for long distance recognition using the cavity structure of the present invention can be recognized even at a long distance of 10m.

While the present invention has been described as a preferred embodiment, the present invention is not limited thereto, and various modifications can be made without departing from the gist of the invention.

1 is a conceptual diagram of a general RFID network,

2 is a view showing a conventional RFID tag structure;

3 is a perspective view of a metal tag structure for long distance recognition using the present invention cavity structure,

4 is a plan view of a metal tag structure for long distance recognition using the cavity structure of the present invention;

5 is a plan view of a metal tag structure for long distance recognition using the cavity structure of the present invention;

6 is a perspective view of a tag casing according to the present invention;

7 is a view showing a state in which a metal tag structure is built in the tag casing according to the present invention;

8 is a graph showing a reflection coefficient of a metal tag structure according to Experimental Example 1 of the present invention;

9A and 9B are graphs showing the measured impedance when the metal tag structure A according to Experimental Example 1 of the present invention is on or without metal,

10A and 10B are diagrams showing the gain of the measured tag antenna when there is no metal plate on the lower surface of the metal tag structure A according to Experimental Example 1 of the present invention;

11A and 11B are diagrams showing the gain of the measured tag antenna when the metal plate is located on the lower surface of the metal tag structure A according to Experimental Example 1 of the present invention;

12 is a graph showing a reflection coefficient of a metal tag structure according to Experimental Example 2 of the present invention;

13A and 13B are graphs showing measured impedances with and without metal tag structures according to Experimental Example 2 of the present invention;

14A and 14B are diagrams illustrating a gain of a measured tag antenna when there is no metal plate on a bottom surface of a metal tag structure according to Experimental Example 2 of the present invention;

15A and 15B are diagrams illustrating the gain of a measured tag antenna when a metal plate is present on a bottom surface of a metal tag structure according to Experimental Example 2 of the present invention;

16a is a photograph of a metal tag structure manufactured according to Example 1 of the present invention;

16b is a photograph of a casing state of a metal tag structure manufactured according to Example 1 of the present invention;

17a is a photograph of a metal tag structure manufactured according to Example 2 of the present invention;

17b is a photograph of a casing state of a metal tag structure manufactured according to Example 2 of the present invention;

18A is a graph showing measured recognition distances of Squiggle2 tags of Examples 1 and 2 of the present invention in a free space without metal;

18B is a graph illustrating measured recognition distances of Embodiments 1 and 2 tags of the present invention with metal attached to a lower surface of a metal tag;

19 is a graph showing the results of sensitivity measurement of the metal tag according to the present invention.

<Explanation of symbols for main parts of drawing>

10: cylinder 20: dielectric film

30 metal film 40 patterning part

50: chip 61: body

62: fastening portion 63: fastening hole

A: Metal tag structure B: Tag casing

Claims (5)

A tag antenna including a cylinder 10 having a hollow portion, a dielectric film 20 formed on an upper surface of the cylinder 10, and a metal film 30 formed at a central portion away from an edge of the dielectric film 20; And a metal tag structure A including the patterning part 40 in which the metal film 30 is patterned in a “T” shaped closed loop, and a chip 50 mounted at one end of the patterning part 40. ; Long-range recognition metal tag using a cavity structure, characterized in that consisting of a tag casing (B) in which the metal tag structure (A) is embedded. The method of claim 1, wherein the cylindrical body 10 is a metal having a dielectric film 20 formed on an upper surface thereof and forming a hollow portion therein, and any one of printing, silkscreen, and etching methods on the dielectric film 20 is formed. Metal tag for long-range recognition using a cavity structure, characterized in that the metal film 30 is formed by the method. 3. The metal tag for long distance recognition using a cavity structure according to claim 2, wherein the cylinder (10), the dielectric film (20) and the metal film (30) form a tag antenna. The method of claim 1, wherein the patterning portion 40 is a portion in which the metal film 30 is removed and the dielectric film 20 is patterned in the form of a "T" shaped closed loop. Long distance recognition metal tag using a cavity structure, characterized in that the chip 50 is mounted. The method of claim 1, wherein the tag casing (B) is formed of any one of ABS, polyester (PE), polycarbonate (PC), or a mixture of at least two or more, or to protect the non-conductive plastic material or circuit. It is made of a non-conductive material, the body 61 having an opening in one side so as to embed the metal tag structure (A); A fastening part 62 in which both ends of the opening side extend horizontally to be integral with the body 61; Long distance recognition metal tag using a cavity structure, characterized in that consisting of a fastening hole (63) formed through the central portion of the fastening portion (62).

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