KR101117112B1 - Broadband rfid metal tag antenna using uhf band and attachable to metal surface - Google Patents

Abstract

The present invention relates to a UHF band RFID tag antenna that can be attached to a metal and to secure a recognition distance in a wide band, and is electrically connected to a ground part, a dielectric part, a ground part, and a short pin that ground the signal of the antenna formed on the metal surface. It relates to a UHF band wideband metal tag antenna, which is formed of a radiator part connected to a feed line connected to the radiator part, and is composed of a double U slot designed to exhibit broadband characteristics based on an RFID tag recognition distance.
Therefore, the present invention forms a double U-slot on the radiator so that even if it is attached to metal in the worldwide UHF band RFID frequency band 860 ~ 960 ㎒, it can be used without changing the antenna performance and the recognition distance of the RFID tag antenna can be improved. Can be.

Description

  BROADBAND RFID METAL TAG ANTENNA USING UHF BAND AND ATTACHABLE TO METAL SURFACE}

The present invention relates to a UHF (Ultra-High Frequency) band RFID-Radio-Frequency IDentification (RFID) metal tag antenna that can be attached to a metal and to secure a recognition distance at a broadband. Folded u-slot designed to reduce the change of recognition distance due to frequency fluctuations and not to affect the performance of RFID tag due to frequency fluctuations and to show broadband characteristics based on RFID tag recognition distance. It relates to a wideband RFID metal tag antenna of the UHF band.

As is known, the structure of an RFID tag antenna attached to a metal generally has an antenna having an inverted L-type structure or a Planar Inverted-F Antenna (PIFA) antenna structure. A representative example of an RFID tag antenna attached to such a metal is Korean Patent Publication No. 10-0819196 (Invention name: UHF band RFID tag antenna which can be attached to a metal; hereinafter referred to as 'quotation invention'), which is shown in FIG. As shown, the ground portion 10 for grounding the signal of the tag antenna 100, the first dielectric portion 20 formed on the upper layer of the ground portion 10, and the first dielectric portion 20 The metal part 30 formed on the upper layer, the second dielectric part 40 formed on the upper layer of the metal part 30 and the upper layer of the second dielectric part 40 have one side with the metal part 30. It consists of a radiating portion 50 formed of a radiating feed line 51 electrically connected to the electrically connected feed line 51 and the radiator 52 connected to the other side of the curved feed line 51, the L-shaped slot 54 in the radiator 52 ).

The cited invention has the effect of reducing the size of the entire tag antenna by forming the L-shaped slot 54 in the radiator 52 and resonating at 1 / 2λ, and the metal part (between the radiating part 50 and the feeding part) 30) is formed in a multi-layered structure, and the maximum and minimum points of the electric field are simultaneously formed in the radiator 50 to reduce the amount of current induced in the ground 10, thereby reducing antenna performance even when the tag antenna is attached at any position. It can be used without change.

However, the structure of such an antenna is close to the distance between the dielectric materials 20 and 40 having a dielectric constant and the radiator 52, and the frequency bandwidth is narrow due to the antenna structure of the cited invention having an L-shaped slot 54. RFID metal tag is recognized only in the bandwidth of about 40 MHz or less, and also has a problem that the recognition distance is shortened to 5 m or less due to low radiation efficiency.

Republic of Korea Patent Publication No. 10-0819196

The object of the present invention is to solve the above problems, while widening the frequency bandwidth of the RFID tag antenna attached to the metal is recognized in more than 80 ㎒ bandwidth of the entire frequency band of the RFID, and also in the 80 ㎒ frequency band is more than 6 m long distance It provides a UHF band wideband RFID metal tag antenna that can be recognized and attached to a metal.

In order to achieve the above object, the present invention provides a grounding part attached to a metal surface, a dielectric part formed on an upper layer of the grounding part, an electric wire path connected by a shorting pin to an upper layer of the dielectric part, and a radiator around the electric wire path. In the metal tag antenna consisting of a radiating portion, a double U-slot (Foled u-Slot) of two U-shaped slots are formed on the radiator formed in the radiating portion, the length of the U-shaped slot (L) And width (W) to adjust the real and imaginary components of the impedance according to the frequency of the RFID tag antenna, and the two radiating parts based on the 900 MHz to 920 MHz frequency interval, which is the center of the 860 MHz to 960 MHz frequency interval The U-shaped slot of one of the U-shaped slots adjusts the impedance component of the high frequency section, and the other U-shaped slot is of the low frequency section. It provides a wide band RFID tag antenna provided with a second metal of the U-slot for adjusting the residence component.

In this way, the present invention forms a double U-slot on the radiator and can be used without change in antenna performance even when attached to metal in the UHF band RFID frequency of 860 to 960 ㎒ worldwide and improves the recognition distance of the RFID tag antenna. It works.

1 is a perspective view showing the structure of the cited invention;
Figure 2 is a block diagram showing the overall configuration of a specific embodiment of a broadband RFID metal tag antenna attachable to metal according to the present invention.
3 and 4 are graphs showing characteristics of a specific embodiment of a broadband RFID metal tag antenna attachable to metal according to the present invention.
5, 6 is an EPC global static test system configuration diagram.
Fig. 7 is a seal photograph of a wideband RFID metal tag attachable to metal according to the present invention attached to a metal plate for EPC global static testing.
8 to 11 are graphs of measurement results.
Fig. 12 is a seal photograph inside a wideband RFID metal tag antenna attachable to metal according to the present invention.

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

The overall configuration of a specific embodiment of a broadband RFID metal tag antenna attachable to metal according to the present invention is shown in FIG.

As can be seen from the above, the present invention is a ground portion (2) attached to the metal surface (1) to ground the signal, a dielectric portion (3) formed on the upper layer of the ground portion 2, and the dielectric In the upper layer of the part 3, an electric wire path 4 electrically connected to the short circuit pin 5, an RFID tag chip is bonded to the electric wire path 4, and placed in an isolated circumference of the electric wire path 4; The U-shaped slots 71 and 72 may be formed of a radiator 6 formed of a radiator 7 etched in an overlapped form.

If you explain this in more detail for each component,

The above-described grounding part 2 and the wire path 4 are electrically connected to each other by using a short circuit pin 5 by drilling a hole in the dielectric, and at the point where the wire path 4 and the radiator 7 are connected, the RFID tag is connected. The chip is laser bonded, and the RFID tag chip is most preferably composed of the Alix Higgs-3 chip, and the impedance of the RFID tag chip is preferably about 20-197 Ω.

In addition, the above-described radiator 7 of the radiator 6 is provided with a double U-slot in which two U-shaped slots 71 and 72 having different sizes surround the RFID tag chip, and the radiator 6 The dielectric material of the lower layer is FR4 (Flame Retardant Type4), and a metal body is directly attached to the ground plane of the ground portion 2.

Here, the two overlapping U-shaped slots 71 and 72 of the above-mentioned radiator 6 adjust the length L and the width W, respectively, so that the real and imaginary components of impedance according to the frequency of the RFID tag antenna are imaginary. The component can be adjusted, the first U-shaped slot (u-slot 1) 71 of the two U-shaped slots (71, 72) adjusts the impedance component of the high frequency based on 860 ~ 960 MHz, the large second U The slot (u-slot2) 72 controls the low frequency impedance component based on 860 to 960 MHz, so that the antenna performance does not change even if it is attached to metal in the UHF band RFID frequency of 860 to 960 MHz. It can be used without and can improve the recognition distance of RFID tag antenna. That is, the grounding part 2 is directly attached to the metal surface 1, and generally, the size of the metal surface 1 has an optimum recognition distance characteristic at 200 * 200 mm and other characteristics are inferior in the present invention. By changing only the length and width of the two U-shaped slots 71 and 72 of the wideband RFID metal tag antenna, it can be used without any change in the antenna performance even if attached to any position on the metal surface (1).

More specifically illustrating a specific embodiment of the wideband RFID metal tag antenna attachable to the metal according to the present invention, the wideband RFID metal tag antenna size is 90 × 50 × 3.2 megahertz (90 (L1) × 50 (W1 in FIG. 2). ) × 3.2 (W5)), the shorting pin (5) consists of a 1 mm hole, the first U-shaped slot 71 is 45 mm (L3) in length, 24 mm (W3) in width, slot width is 2 mm, 2 U-shaped slot 72 has the characteristics as shown in Figs. 3 and 4 when the length is 75 mm (L2), width 40 mm (W2), the slot width is 2mm.

3 and 4 are simulation results of the tag antenna of the present invention considering the metal plane. 3 and 4 show the return loss of the tag antenna and the Smith chart of the tag antenna, respectively. As shown in FIGS. 3 and 4, it can be seen that the impedance change is insensitive to frequency.

1. Also, in order to measure the characteristics / performance of the wideband RFID metal tag antenna, as shown in FIGS. 5 and 6, two signal generators, an RFID emulator, and a spectrum analyzer ( Spectrum Analyzer) and an interface box for interfacing them, and a broadband RFID metal tag comprising a broadband RFID metal tag antenna according to the present invention is installed at a height of 1.6m from the bottom of a shielded room where reflected waves are blocked. A measurement environment was established by installing a transmitter and a receiver for transmitting and receiving through the interface box at a distance of 0.93m from the wideband RFID metal tag.

At this time, the broadband RFID metal tag was attached to the metal surface (1) of 200 × 200mm ² size in consideration of the real environment, and then the EPC global static test was performed. Center frequency).

The read range measurement procedure for such a wideband RFID metal tag is

1) Emits fixed frequency and phase revered-amplitude shift keying (PR-ASK) signals

2) The signal is emitted at the minimum EIRP to receive the tag response.

3) Record the EIRP at the point where the success read rate is 50% by increasing the effective isotropically radiated power (EIRP) in 0.25dB increments.

4) Record the EIRP at the point where the read success rate is 50% or more while increasing the EIRP of 3) by 1 dB and decreasing it by 0.25 dB.

In the formula above, r = distance from the transmitter stage to the tag

Mean (EIRP _TX ) = 3) and 4) Calculate the mean of the results

Was measured in order of the read range, the tag sensitivity alignment tolerance (Orientation Tolerance) measurement procedures for the (Tag sensitivity) determined according to the orientation of the tag antenna is

6) The reading range is obtained through 1) to 5). Azimuth angle and elevation angle are 0 °

2. 7) EIRP is calculated for both azimuth angles by turning the azimuth angle counterclockwise sequentially from 10, 20, 30 to 90 degrees.

8) Find EIRP for negative azimuth.

9) Obtain EIRP for both elevation angles (upward rotations).

10) Obtain EIRP for the sound elevation.

And so on. As a result, a recognition distance graph according to the direction of the tag antenna as shown in FIG. 8 may be obtained.

In addition, the frequency tolerance measurement procedure to find the tag sensitivity

11) Obtain the reading range from 1) to 5) at 860MHz.

12) Obtain the reading range up to 960 MHz in 5 MHz increments (21 total).

13) The result obtained in 12) is displayed as shown in FIG. 9.

14) Find the frequency tolerance (%) using the formula below.

The frequency tolerance can be obtained by proceeding in the order of.

Looking at the measurement results of the broadband UHF band RFID metal tag antenna attachable to the metal according to the present invention by such a measurement procedure,

The measurement result of reading range is maximum recognition distance 8.32 m and Korea frequency recognition distance 7.60 m (@ 911.25 ㎒).

3. Orientation Tolerance measurement result is shown in the table shown in Fig. 10, the maximum recognition distance of the orientation tolerance measurement result is 7.87 m,

As a result of the azimuth measurement, the beam width of the wide-band metal tag was -20 ° to 50 ° based on the recognition distance of 6m and was about 70 °.

The elevation angle measurement result shows that the wide metal tag beam width has a good beam width of -30 ° to 30 ° based on a recognition distance of about 60 °.

Based on the measurement of orientation tolerance, the developed wideband metal tag can recognize more than 6m of recognition distance up to about 60 ° up and down and about 70 ° from side to side.

In addition, looking at the frequency tolerance measurement results, as shown in the table shown in Figure 11, the frequency tolerance measurement result of the broadband metal tag bandwidth of 80 ㎒ (based on 6 m recognition distance) It can be confirmed that it has the recognition distance performance, and the broadband metal tag bandwidth is 880 ~ 960 ㎒, which is the highest performance in the world.

As described above, the present invention is not limited to the above-described embodiments, but can be variously changed within the spirit and concept of the present invention.

1: metal surface 2: ground portion 3: dielectric portion
4: Cable line 5: Short circuit pin 6: Radiator
7: radiator 71: first U-shaped slot 72: second U-shaped slot

Claims (5)

delete In a metal tag antenna consisting of a ground portion attached to a metal surface, a dielectric portion formed on the upper layer of the ground portion, an electric wire path connected to the upper layer by a short circuit pin, and a radiator formed around the electric wire path in a radiator. ,
A double u-slot having a form in which two U-shaped slots are superposed on the radiator formed on the radiating part is provided,
Adjusting the length (L) and width (W) of the U-shaped slot to adjust the real and imaginary components of the impedance according to the frequency of the RFID tag antenna,
The U-shaped slot of one of the two U-shaped slots of the radiator adjusts the impedance component of the high frequency section based on the 900 MHz to 920 MHz frequency section that is the center of the 860 MHz to 960 MHz frequency sections. The slot is a metal attachable broadband RFID metal tag antenna using a HH band characterized in that to adjust the impedance component of the low frequency section based on the 900MHz to 920MHz frequency section of the center of the 860MHz to 960MHz frequency section. The method of claim 2,
The size of the first U-shaped slot, which is one of the two overlapping U-shaped slots of the radiator, is 45 mm long, 24 mm wide, and the slot width is 2 mm, and the size of the second U-shaped slot which is the other is 75 mm long. A metal attachable broadband RFID metal tag antenna using the HHF band, wherein the width is 40 mm and the slot width is 2 mm. The method of claim 2,
The small first U-shaped slot of the two overlapping U-shaped slots of the radiator adjusts the impedance component of the high frequency section based on the 900 MHz to 920 MHz frequency section, which is the center of the 860 MHz to 960 MHz frequency section, and the size. The second large U-shaped slot is a metal attachable broadband RF band using the H. F band which adjusts the impedance component of the low frequency section based on the 900 MHz to 920 MHz frequency which is the center of the 860 MHz to 960 MHz frequency sections. ID metal tag antenna.
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