KR20100074541A - Rfid tag antenna - Google Patents

Abstract

PURPOSE: An RFID tag antenna is provided to control a resistance element of impedance by controlling the length width of first and second microstrip patches. CONSTITUTION: First and second microstrip patches(311,312) are arranged on the upper side of a dielectric(310). The first and second microstrip patches have a rectangular slot. The tag chip and the capacitor element are arranged between the first and second microstrip patches. A feeding terminal connects the tag chip to the first and second microstrip patches. A first ground plate(313) is vertically bended from one side of the first microstrip patch. A second ground plate(314) is vertically bended from one side of the second microstrip patch.

Description

RFID tag antenna {RFID TAG ANTENNA}

The present invention relates to an RFID (Radio Frequency IDentification) tag antenna, and more particularly, by constructing a plurality of microstrip patches facing each other so as to separate the tag chip and the capacitor element in parallel, thereby providing a small resistance component and a large capacitive reactance. The present invention relates to an RFID tag antenna that provides an efficient impedance matching to have a (capacitive reactance) component.

RFID tags are used in various fields, such as material management or security, with RFID readers or interrogatiors. In general, when an object with an RFID tag is placed in a read zone of the RFID reader, the RFID reader modulates an RF signal having a specific carrier frequency to transmit an interrogation signal to the tag. The RFID tag will respond to the reader's questions.

That is, the RFID reader modulates a continuous electromagnetic wave having a specific frequency to transmit a question signal to the tag, and the RFID tag emits electromagnetic waves from the reader in order to deliver its information stored in the internal memory to the reader. Return back to the reader by back-scattering modulation. Backscatter modulation is a method of transmitting information of a tag by modulating the magnitude and phase of the scattered electromagnetic wave when the tag scatters the electromagnetic wave sent from the reader and sends it back to the reader.

On the other hand, the passive RFID tag rectifies the electromagnetic wave transmitted from the reader and uses it as its operating power source. Therefore, in order for the passive tag to operate normally, the signal received by the tag should be greater than or equal to a certain threshold, and in order to improve the read range, the power of the reader should be increased.

However, the power output of the reader is not subject to large size because it is regulated by local regulations of each country including the US Federal Communication Commission (FCC).

In order to maximize the recognition distance for the power of a given reader, the tag antenna should efficiently receive the electromagnetic wave transmitted from the reader and transmit it to the RF front-end of the tag without loss. To this end, the tag antenna should be designed to have a high radiation efficiency and a conjugate match with the RF front end of the tag.

One method of improving the recognition distance of the RFID tag is to use a separate matching circuit between the antenna and the RF front end of the tag, but in general, the RFID tag includes an antenna, an RF front end, and a signal processing part. The RF front end and the signal processing part are made of one chip.

In addition, a method of using a matching circuit is a method of maximizing the strength of a signal transmitted from the antenna to the RF front end by conjugate matching the antenna and the RF front end through a separate matching circuit.

However, since a matching circuit composed of a combination of a capacitor and an inductor requires a large area in the chip, it is difficult to include it inside the chip in terms of miniaturization and cost.

The present invention has been made to solve the above problems, an object of the present invention is to provide a tag chip and a capacitor element provided between the first microstrip patch and the second microstrip patch in parallel, so that the tag chip is small It has a resistive component and a large capacitive reactance component to provide efficient impedance matching.

The RFID tag antenna according to the present invention for achieving the technical problem, the first microstrip patch is formed on the dielectric, the first microstrip patch to form a slot of the rectangular structure from one end to the inside is seated on the dielectric upper surface A second microstrip patch spaced apart from each other in the same structure as the first microstrip patch, a power supply terminal provided between the first microstrip patch and the second microstrip patch, and spaced in parallel with the power supply terminal in parallel with the first microstrip patch; A capacitor element provided between the microstrip patch and the second microstrip patch, a first ground plate that is bent vertically from the outer circumferential end surface of the first microstrip patch and grounded with the ground plane provided to allow the dielectric to be seated, and the second micro Bent vertically from the other end of the strip patch and grounded The board comprises a second ground.

In addition, one end is characterized in that the opposite surface end of the first microstrip patch and the second microstrip patch.

)가 유도성 리액턴스 성분(

)을 갖도록 유도하는 것을 특징으로 한다.In addition, the capacitor element is connected in parallel with the power supply terminal so that the impedance of the antenna (

) Is an inductive reactance component (

It is characterized by inducing to have.

The capacitor device may be a chip capacitor or a variable capacitor in the form of a multi-layer ceramic capacitor (MLCC).

In addition, when the first microstrip patch and the second microstrip patch are used in the 900 MHz band, the horizontal length is 5 mm to 50 mm, and the vertical widths 316 and 317 are 5 mm to 50 mm, preferably the horizontal length is 20 mm, the vertical width is It is characterized in that 20mm.

In addition, the slot is characterized in that the horizontal length is 1mm to 10mm, the vertical width is 0.5mm to 5mm, preferably the horizontal length is 3mm, the vertical width is 1mm.

In addition, the separation distance between the tag chip and the capacitor element is characterized in that 0mm to 50mm, preferably 2mm.

The first microstrip patch and the second microstrip patch may be any one of a quadrangular shape, a polygonal shape including a triangular shape, and a circular shape.

And at least one capacitor element is characterized by the above-mentioned.

On the other hand, RFID tag antenna according to another embodiment of the present invention, is provided in the shape of any one of a dielectric, a polygonal shape including a rectangular shape, a triangular shape, and a circular shape seated on the dielectric upper surface, A first microstrip patch forming a streamlined first long groove, and a second micro seated on the dielectric upper surface and spaced apart from each other in the same structure as the first microstrip patch, to form a streamlined second long groove therein. A power supply terminal provided between the strip patch, the first microstrip patch and the second microstrip patch, at least one capacitor element provided between the first microstrip patch and the second microstrip patch, and the first microstrip patch A first ground plate bent vertically from the outer circumference of the outer periphery of the ground and grounded with the ground plane, and the other end of the second microstrip patch And a second ground plate bent vertically from the stage and grounded with the ground plane.

In addition, the streamlined long groove has a radius of 5 mm to 50 mm of the outer circumference, 4 mm to 45 mm of the other inner circumference, and a width of the streamlined long groove of 0.5 mm to 5 mm, preferably 25 mm of the outer circumference, and a radius of the inner circumference. 24mm, and the width of the long groove is characterized in that 1mm.

According to the present invention as described above, by adjusting the vertical width of the first and second microstrip patches to adjust the resistance component of the antenna impedance, the horizontal length of the first and second microstrip patches, and the capacitance of the capacitor element By adjusting the reactance component of the antenna impedance by adjusting the position, and the shape and position of the slot, there is an effect of providing a small resistance component and a large capacitive reactance component to provide efficient matching of the tag chip and the RF front end.

Specific features and advantages of the present invention will become more apparent from the following detailed description based on the accompanying drawings. Prior to this, the terms or words used in the present specification and claims are defined in the technical spirit of the present invention on the basis of the principle that the inventor can appropriately define the concept of the term in order to explain his invention in the best way. It should be interpreted to mean meanings and concepts. It is to be noted that the detailed description of known functions and constructions related to the present invention is omitted when it is determined that the gist of the present invention may be unnecessarily blurred.

1 is a view showing the configuration of the RFID system 100 to be applied to the present invention, as shown is configured to include an RFID reader 110 and RFID tag 120.

Specifically, the RFID reader 110 transmits an RF signal to the RFID tag 120 through the RF transmitter 111 and the reader antenna 113, and the RFID tag 120 through the reader antenna 113 and the RF receiver 112. Receive an RF signal.

Also, the RFID tag 120 converts the received RF signal into a DC voltage to supply the power necessary for the signal processor 122 to operate, and extracts the baseband signal from the received RF signal. .

Since the configurations of the RFID reader 110 and the RFID tag 120 are well known in the art, detailed descriptions thereof will be omitted.

On the other hand, look at the operation of the RFID system 100 according to the present invention.

First, the RFID reader 110 modulates an RF signal having a specific carrier frequency and transmits an interrogation to the RFID tag 120, and the RF generated by the RF transmitter 111 of the RFID reader 110. The signal transmits the question to the outside through the reader antenna 113 in the form of the electromagnetic wave 130.

Subsequently, the tag antenna 123 transmits the electromagnetic wave 130 transmitted from the RF transmitter 111 to the RF front end 121, and the RF front end 121 transmits the received RF signal size of the RFID to the RFID. If the minimum required power for the operation of the tag 120, the RFID tag 120 backscatters the electromagnetic wave 130 transmitted from the RFID reader 110 to answer the question of the RFID reader 110.

In this case, in order to improve the recognition distance of the RFID system 100, the electromagnetic wave 130 transmitted from the tag antenna 123 to the RF front end 121 should efficiently transmit with minimal loss. The impedance of the antenna 123 and the impedance of the RF front end 121 should be conjugated.

) 및 안테나 임피던스(

)로 구성되고, RF 전단부(121)의 등가회로는 RF 전단부 임피던스(

)로 구성된다.2 is an equivalent circuit diagram of a tag antenna 123 and an RF front end 121 of the RFID system 100 applied to the present invention. The equivalent circuit of the tag antenna 123 is a voltage source (

) And antenna impedance (

) And the equivalent circuit of the RF front end portion 121 has an RF front end impedance (

It is composed of

)는 저항(resistance) 성분(

)과 리액턴스(reactance) 성분(

)을 가진다. RF 전단부의 임피던스 역시 저항 성분(

)과 리액턴스 성분(

)을 가진다.Antenna impedance (

) Is the resistance component (

) And reactance components (

) The impedance of the RF front end is also the resistance component (

) And reactance component (

)

)와 RF 전단부의 임피던스(

)를 공액 정합시키면, 태그 안테나(123)로부터 RF 전단부(121)에 최대 전력이 전달된다. 여기서, 공액 정합이란, 두 복소(complex) 임피던스에 대해, 임피던스의 절대값의 크기가 같고, 위상이 서로 반대 부호를 갖도록 하는 것이다. 즉,

이고,

가 되도록 태그 안테나(123)의 임피던스 또는 RF 전단부(121)의 임피던스를 조정하면 태그 안테나(123)로부터 RF 전단부(121)에 최대 전력이 전달된다.In general, the antenna impedance (

) And the impedance of the RF front end (

) Conjugately transfers maximum power from the tag antenna 123 to the RF front end 121. Here, conjugate matching means that the magnitudes of the absolute values of the impedances are the same for the two complex impedances, and the phases have opposite signs. In other words,

ego,

When the impedance of the tag antenna 123 or the impedance of the RF front end 121 is adjusted to be, the maximum power is transmitted from the tag antenna 123 to the RF front end 121.

)과 큰 용량성(capacitive) 리액턴스 성분(

)을 가진다.In addition, the RF front end 121 of the passive or semi-passive RFID tag chip is composed of a rectification and detection circuit using a diode, and does not include a separate matching circuit to reduce the area of the chip. Therefore, the impedance of the RF front end 121 has a complex impedance different from that of the usual 50 Hz, and due to the characteristics of the rectifying and detecting circuit, a small resistance component in the UHF band (

) And a large capacitive reactance component (

)

)는 작은 저항 성분(

)과 큰 유도성(inductive) 리액턴스 성분(

)을 가져야 한다.Antenna impedance for conjugate matching

) Is a small resistance component (

) And large inductive reactance components (

Must have

Hereinafter, referring to the RFID tag antenna 300 according to an embodiment of the present invention with reference to FIG. 3, the first microstrip patch 311 is provided to be seated on the upper surface of the dielectric 310, from one end to the inside. A slot 322 having a rectangular structure is formed, and the second microstrip patch 312 is seated on the dielectric upper surface, and is spaced apart to face the first microstrip patch in the same structure, and forms the slot 323. Here, the slots 322 and 323 can adjust the fine impedance of the antenna impedance according to the size.

Here, the shape of the first and second microstrip packages 311 and 312 may be any one of a rectangular shape, a polygonal shape including a triangle shape, and a circular shape.

When used in the 900 MHz band, the horizontal lengths 318 and 319 of the first microstrip patch and the second microstrip patch are 5 mm to 50 mm, and the vertical widths 316 and 317 are 5 mm to 50 mm, preferably the horizontal length 318. 319 is 20mm, the vertical width (316, 317) is characterized in that 20mm, the width of the slot is 1mm to 10mm, the vertical width is 0.5mm to 5mm, preferably the horizontal length is 3mm, the vertical width is 1mm However, the present invention is not limited thereto.

The tag chip 330 is provided between the first microstrip patch 311 and the second microstrip patch 312, and the capacitor element 321 is spaced in parallel with the tag chip 330 so as to space the first microstrip patch. It is provided between the 311 and the second microstrip patch 312, the power supply terminals 331, 332 connects the tag chip 330 with the first microstrip patch and the second microstrip patch, respectively.

)가 유도성 리액턴스 성분(

)을 갖도록 유도하게 된다. 이때, 태그 칩(330)과 커패시터 소자(321)간의 이격 거리는 0mm 내지 50mm, 바람직하게는 2mm인 것을 특징으로 하나, 본 발명이 이에 국한되는 것은 아니다.That is, as the tag chip 330 is connected in parallel with the capacitor element 321, the impedance of the antenna (

) Is an inductive reactance component (

Will be induced to have At this time, the separation distance between the tag chip 330 and the capacitor element 321 is characterized in that 0mm to 50mm, preferably 2mm, but the present invention is not limited thereto.

In addition, the capacitor device 321 is characterized in that the chip capacitor (chip capacitor) or a variable capacitor of the MLCC (Multi Layer Ceramic Capacitor) type, the capacitor device 321 of the present invention is not limited thereto. It is provided with at least one.

Dielectric 310 seats first and second microstrip patches 311 and 312 on its top surface, and dielectric 310 sits on top of ground plane 315.

The first ground plate 313 is bent vertically from the outer circumferential end surface of the one microstrip patch 311 to be grounded with the ground plane 315, and the second ground plate 314 is the outer circumference of the two microstrip patches 312. It is bent vertically from the longitudinal section and grounded with the ground plane 315.

Here, the first and second ground plates 313 and 314 are not limited to those having the same area as the outer peripheral end surfaces of the first and second microstrip patches 311 and 312, and may include a plurality of shorting pins. Through the configuration, the left and right microstrip patches 311 and 312 and the ground plane 315 can be shorted.

)에 대한 저항 성분(

)과, 안테나 임피던스(

)에 대한 리액턴스 성분(

)에 대해 살핀다.Hereinafter, the antenna impedance of the RFID tag antenna 300 according to an embodiment of the present invention (

Resistance to)

) And antenna impedance (

Reactance component for

Look at).

)의 저항 성분(

)은 상기 제1 및 제2 마이크로스트립 패치(311, 312)의 세로 폭(316, 317)에 의해 결정되며, 이는, 제1 및 제2 마이크로스트립 패치(311, 312)의 개방단의 세로 폭에 의하여 안테나의 복사 저항(radiation resistance)이 크게 달라지기 때문이다.Given the thickness and dielectric constant of dielectric 310, antenna impedance (

Resistance component of

) Is determined by the longitudinal widths 316, 317 of the first and second microstrip patches 311, 312, which are the longitudinal widths of the open ends of the first and second microstrip patches 311, 312. This is because the radiation resistance of the antenna varies greatly.

)의 저항 성분(

)이 커지고, 상기 유전체(310)의 유전 손실(dielectric loss)이 증가할수록 안테나 임피던스(

)의 저항 성분(

)이 증가한다.That is, as the vertical widths 316 and 317 of the first and second microstrip patches 311 and 312 increase, the antenna impedance (

Resistance component of

) Increases, and as the dielectric loss of the dielectric 310 increases, antenna impedance (

Resistance component of

) Increases.

)의 리액턴스 성분(

)은 상기 제1 및 제2 마이크로스트립 패치(311, 312)의 세로 폭(316, 317)과 가로 길이(318, 319)에 의해 결정된다.On the other hand, given the thickness and dielectric constant of the dielectric 310, the antenna impedance (

Reactance component of

) Is determined by the vertical widths 316 and 317 and the horizontal lengths 318 and 319 of the first and second microstrip patches 311 and 312.

The horizontal lengths 318 and 319 of the first and second microstrip patches 311 and 312 do not exceed 0.25 times the wavelength corresponding to the antenna operating frequency, where the antenna is inductive reactance. Has

)의 리액턴스 성분(

)의 크기가 커며, 제1 및 제2 마이크로스트립 패치(311, 312)의 세로 폭(316, 317) 및 가로 길이(318, 319)는 각각 서로 다르게 형성될 수 있다.Also, the longer the lateral lengths 318 and 319 of the first and second microstrip patches 311 and 312 for the longitudinal widths 316 and 317 of the given first and second microstrip patches 311 and 312, the longer the antenna. impedance(

Reactance component of

) Is large, and the vertical widths 316 and 317 and the horizontal lengths 318 and 319 of the first and second microstrip patches 311 and 312 may be formed differently from each other.

)을 얻을 수 없다.In addition, in order to downsize the RFID tag antenna 300, there are cases where the vertical widths 316 and 317 and the horizontal lengths 318 and 319 of the first and second microstrip patches 311 and 312 are limited. In this case, the desired reactance component can be adjusted by simply adjusting the widths 318 and 319 and the widths 316 and 317 of the first and second microstrip patches 311 and 312.

Can't get)

In such a case, it is easy to think that a short-length microstrip patch and slot can be configured to obtain a desired reactance component. However, as the size of the slot increases, unnecessary radiation increases in the slot. reveals a significant decrease in the radiation efficiency.

This problem is solved by adding the capacitive reactance by attaching the capacitor elements 321 in parallel to the power supply terminals 331 and 332 provided for connecting the tag chip 330 as described above.

)의 유도성 리액턴스 성분(

)의 크기를 증가시킬 수 있다. 다만, 커패시터 소자(321)의 커패시턴스를 너무 크게 하면, RFID 태그 안테나(300) 임피던스(

)는 용량성 리액턴스를 가지게 된다.In other words, if the capacitance of the capacitor element 321 is gradually increased, the impedance of the RFID tag antenna 300 according to the embodiment of the present invention (

Inductive reactance component of

) Can increase the size. However, if the capacitance of the capacitor element 321 is too large, the impedance of the RFID tag antenna 300 (

) Has a capacitive reactance.

)는 용량성 리액턴스 성분(

)을 가지므로, 공액 정합을 위해 RFID 태그 안테나(300) 임피던스(

)는 유도성 리액턴스 성분(

)을 가지도록 상기 커패시터 소자(321)의 커패시턴스를 조정할 수 있다.In addition, the input impedance of the tag chip 330 (

) Is the capacitive reactance component (

), The impedance of the RFID tag antenna 300 for conjugate matching

) Is the inductive reactance component (

It is possible to adjust the capacitance of the capacitor element 321 to have.

On the other hand, commercially available values of capacitor elements are not continuous and have discrete values (eg, 3.3 pF, 3.6 pF, and 3.9 pF, etc.).

Therefore, in order to finely adjust the impedance of the RFID tag antenna 300 according to the present invention, the distance 324 between the tag chip 330 and the capacitor element 321 is adjusted or the first and second microstrips are adjusted. The sizes of the slots 322 and 323 formed in a rectangular structure inward from one end of the patches 311 and 312 are adjusted.

At this time, the larger the size of the slots (322, 323) can increase the capacitive reactance, but because the total radiation efficiency may be lowered due to unnecessary radiation in the slots (322, 323) the capacitor element 321 It is desirable to adjust the reactance of the impedance in a large range by using the design, and to design the slots 322 and 323 to have the smallest possible size for fine adjustment.

On the other hand, the slots 322 and 323 according to an embodiment of the present invention shown in Figure 3 is composed of a straight rectangular insertion groove, as shown in (a) and (b) of Figure 4, the present invention According to another embodiment of the RFID tag antenna, a rectangular long groove (401, 402, 403, 404) is formed in the rectangular interior of the first and second microstrip patches (311, 312) not limited to a specific position. Fine impedance of the antenna impedance can be adjusted.

At this time, the streamlined long grooves 401, 402, 403, 404, the radius of the outer circumference 5mm to 50mm, the radius of the other inner circumference is 4mm to 45mm, and the width of the streamlined long groove is 0.5mm to 5mm, preferably the outer The radius of the circumference is 25mm, the radius of the inner circumference is 24mm, and the width of the long groove is characterized in that 1mm.

In addition, the capacitor element 321 shown in FIG. 3 is configured to be connected to the first and second microstrip patches 311 and 312 in a single piece, but as shown in FIG. By connecting the capacitor element 410 with the first and second microstrip patches 311 and 312, the antenna efficiency may be increased by increasing the quality factor Q of the entire capacitor.

)의 저항성분(

)을 조정하고, 제1 및 제2 마이크로스트립 패치(311, 312)의 가로 길이(318, 319)와, 커패시터 소자(321, 410)의 커패시턴스와 구비되는 위치, 및 슬롯(322, 323)과 유선형 장홈(401, 402, 403, 404)의 모양 및 위치를 조정하여 안테나 임피던스의 리액턴스 성분(

)을 조정할 수 있으므로, 작은 저항 성분과 큰 용량성 리액턴스 성분을 제공하여 태그 칩(330)과 RF 전단부(121)의 효율적인 정합이 가능하다.As described above, the RFID tag antenna 300 according to the present invention adjusts the vertical widths 316 and 317 of the first and second microstrip patches 311 and 312 to adjust the antenna impedance (

Resistance component of

And the widths 318 and 319 of the first and second microstrip patches 311 and 312, the capacitance of the capacitor elements 321 and 410, and the slots 322 and 323. Adjust the shape and position of the streamlined long grooves 401, 402, 403, 404 to adjust the reactance component of the antenna impedance (

), A small resistance component and a large capacitive reactance component can be provided to enable efficient matching of the tag chip 330 and the RF front end 121.

As described above and described with reference to a preferred embodiment for illustrating the technical idea of the present invention, the present invention is not limited to the configuration and operation as shown and described as described above, it is a deviation from the scope of the technical idea It will be understood by those skilled in the art that many modifications and variations can be made to the invention without departing from the scope of the invention. Accordingly, all such suitable changes and modifications and equivalents should be considered to be within the scope of the present invention.

1 is a view showing the configuration of an RFID system 100 applied to the present invention.

2 is an equivalent circuit diagram modeling the tag antenna 123 and the RF front end 121 of the RFID system 100 applied to the present invention.

3 is a block diagram showing an RFID tag antenna 300 according to an embodiment of the present invention.

4 is a view illustrating a capacitor device provided with a plurality of slots and a changed position of the RFID tag antenna 300 according to an embodiment of the present invention.

** Description of symbols for the main parts of the drawing **

100: RFID system 110: RFID reader

111: RF transmitter 112: RF receiver

113: reader antenna 120: RFID tag

121: RF front end 122: signal processing unit

123: tag antenna 130: electromagnetic waves

300: RFID tag antenna 310: dielectric

311: first microstrip patch 312: second microstrip patch

313: first ground plate 314: second ground plate

315: ground plane

316, 317: longitudinal width of the first and second microstrip patches

318, 319: transverse length of the first and second microstrip patches

321, 410: capacitor element

322, 323: slot

324: spacing between tag chip and capacitor element

330: tag chip

331, 332: feed terminal

401, 402, 403, 404: streamlined long groove

Claims (11)

RFID tag antenna, dielectric; A first microstrip patch seated on the dielectric upper surface to form a slot of a rectangular structure inwardly from one end thereof; A second microstrip patch seated on the dielectric upper surface and spaced apart from each other in the same structure as the first microstrip patch; A power supply terminal provided between the first microstrip patch and the second microstrip patch; A capacitor device spaced apart in parallel with the feed terminal and disposed between the first microstrip patch and the second microstrip patch; A first ground plate bent vertically from an outer circumferential end surface of the first microstrip patch and grounded with a ground plane provided to seat the dielectric; And A second ground plate bent vertically from the other end of the second microstrip patch and grounded with the ground plane; RFID tag antenna comprising a. The method of claim 1, The one end is, And an opposite end of the first microstrip patch and the second microstrip patch. The method of claim 1, The capacitor device, Is connected in parallel with the feed terminal to

) Is an inductive reactance component (

RFID tag antenna characterized in that it has a). The method of claim 1, The capacitor device, RFID tag antenna characterized in that the chip capacitor (chip capacitor) or variable capacitor (MLCC) type of multi-layer ceramic capacitor. The method of claim 1, The first microstrip patch and the second microstrip patch, When used in the 900MHz band, the RFID tag antenna, characterized in that 5mm to 50mm in width, 5mm to 50mm in width, preferably 20mm in width, 20mm in width. The method of claim 1, The slot is, When used in the 900MHz band, the RFID tag antenna, characterized in that 1mm to 10mm in width, 0.5mm to 5mm in width, preferably 3mm in width, 1mm in width. The method of claim 1, The separation distance between the tag chip and the capacitor element is an RFID tag antenna, characterized in that 0mm to 50mm, preferably 2mm. The method of claim 1, The first microstrip patch and the second microstrip patch, RFID tag antenna, characterized in that any one of a rectangular shape, a polygonal shape including a triangular shape, and a circular shape. The method of claim 1, The capacitor device, RFID tag antenna, characterized in that provided with at least one or more. RFID tag antenna, dielectric; A first microstrip patch seated on the dielectric upper surface and provided in any one of a quadrangular shape, a polygonal shape including a triangular shape, and a circular shape, and forming a first long groove in a streamline; A second microstrip patch seated on the dielectric upper surface and spaced apart from each other in the same structure as the first microstrip patch, and having a streamlined second long groove therein; A power supply terminal provided between the first microstrip patch and the second microstrip patch; At least one capacitor device disposed between the first microstrip patch and the second microstrip patch; A first ground plate bent vertically from an outer circumferential end surface of the first microstrip patch and grounded with a ground plane provided to seat the dielectric; And A second ground plate bent vertically from the other end of the second microstrip patch and grounded with the ground plane; RFID tag antenna comprising a. The method of claim 10, The streamlined long groove, Radius of outer circumference 5mm to 50mm, radius of other inner circumference is 4mm to 45mm, and width of linear linear groove is 0.5mm to 5mm, preferably radius of the outer circumference is 25mm, radius of inner circumference is 24mm, and long groove RFID tag antenna, characterized in that the width of 1mm.

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