KR20080050022A - Bow tie type antenna, radio frequency identification tag including the same and impedance matching method thereof - Google Patents

Abstract

A bow tie type antenna, a radio frequency identification tag including the same, and an impedance matching method using the same are provided to improve antenna design efficiency by flexibly dealing with impedance variation according to complex characteristic variation loss. A bow tie type antenna includes a pair of triangle pattern antennas(110,110'). The bow tie type antenna is provided in a radio frequency identification tag. The triangle pattern antennas include two sides and a bottom side. The triangle pattern antennas are opposed to each other. The triangle antenna patterns include one or more geometrical structures selected from slots(111,111'), a stub, and a patch. The slots are formed on the both sides of the triangle pattern antenna in concave and convex shapes arranged by regular intervals. The slots are arranged in a zigzag pattern.

Description

Bow tie type antenna, radio recognition tag having same and impedance matching method using same {Bow tie type antenna, Radio frequency identification tag including the same and Impedance matching method

The following drawings, which are attached to this specification, illustrate exemplary embodiments of the present invention, and together with the detailed description of the present invention, serve to further understand the technical spirit of the present invention. It should not be construed as limited to.

1 is a circuit diagram schematically showing a configuration of a rectenna including an antenna and a rectifier circuit according to the prior art.

FIG. 2 is a circuit diagram for describing impedance matching between an antenna and a chip of FIG. 1. FIG.

Figure 3 is a plan view showing the structure of a radio recognition tag having a bow tie antenna according to the prior art.

Figure 4 is a plan view showing a radio recognition tag having a bow-tie antenna with a slot formed in accordance with a preferred embodiment of the present invention.

5 and 6 are a plan view showing a radio recognition tag having a bow tie antenna having a stub according to a preferred embodiment of the present invention.

Figure 7 is a plan view showing a radio recognition tag having a bow-tie antenna with a patch formed in accordance with a preferred embodiment of the present invention.

8 and 9 are plan views illustrating radio recognition tags having a bow tie antenna with slots and stubs formed therein.

10 is a plan view illustrating a radio recognition tag having a bow tie antenna with a slot and a patch formed thereon.

<Description of Major Reference Marks in Drawing>

110 to 170, 110 'to 170' ... triangular pattern antenna

111, 111 ', 151, 151', 161, 161 ', 171, 171' ... slots

121, 121 ', 131, 131', 152, 152 ', 162, 162' ... stub

141, 141 ', 172, 172' ... Patch

200 ... tag chip

The present invention relates to a bow tie-type antenna, a radio recognition tag having the same, and an impedance matching method using the same. More particularly, the antenna of the antenna constituting the radio recognition tag can be stably used in a wider band. The present invention relates to a bowtie antenna having an improved geometry, a radio recognition tag having the same, and an impedance matching method using the same.

Radio Frequency IDentification (RFID) systems include tags, readers and readers that read and decipher, host computers, and network networks. It is a system that can read the data embedded in the chip of the radio tag.

In a radio recognition system, a tag includes a chip for storing data of an object and an antenna connected to the chip. Here, the tag and the reader operate by exchanging electromagnetic energy, and the antenna transmits and receives electromagnetic waves for transmitting and receiving data with the reader.

In addition, the tag is classified into an active tag that uses its own power supply and a passive tag that does not have its own power source. Since the passive tag does not have its own power supply unit, the tag can be reduced in size and weight at a lower cost than the active tag. It is suitable for wireless recognition systems that require multiple tags.

The passive tag converts the radio wave transmitted from the reader into electric power. A process of converting the electric wave into electric power will be described with reference to FIG. 1.

As shown in FIG. 1, a radio frequency (RF) signal 3 transmitted from a reader is received by the antenna 1, and the received radio frequency signal 3 is received by the rectifier circuit 2 by a direct current power source ( V _DC ), and the converted DC power is applied as a driving power to a chip (not shown). Accordingly, the passive tag may rectify a part of the radio waves transmitted from the reader without using a separate battery to reproduce the DC power source for driving the chip.

Here, impedance matching should be considered in the design of a rectenna including an antenna and a rectifier circuit. Referring to FIG. 2, impedance matching between the antenna and the chip of FIG. 1 will be described as follows.

As shown in FIG. 2, the feed point impedance Z _a of the antenna 1 ′ and the input impedance Z _c of the chip 2 ′ have a resistance component and a reactance component satisfying Equation 1 below. If the impedance matching between the antenna 1 'and the chip 2' is not performed, the reflected wave is generated and the standing wave is loaded on the feed line. -jX) cancel each other to achieve impedance matching.

Although a separate matching circuit can be configured as a method for implementing the above-described impedance matching, it is difficult to embed coils and capacitors for the impedance matching on the chip, and the addition of the matching circuit leads to high cost and size increase. The antenna is designed to cancel the reactance component of the chip.

On the other hand, the antenna used for the tag has an impedance change almost independent of the frequency change, has a wider band characteristic than the broadband antenna, and includes an Equliangular Spiral antenna and Archimedes Spiral antenna. It is classified into a distributed antenna and a non-distributed antenna including a TEM horn antenna, a biconical antenna, and a bow-tie antenna.

In particular, the bowtie antenna has a simpler structure than other broadband antennas, and is easy to design to achieve impedance matching by canceling the reactance component of the chip. Referring to FIG. Referring to the impedance adjustment method according to the structure as follows.

As shown in FIG. 3, the RFID tag 10 includes a chip 11 and bow tie antennas 12 and 12 ′ electrically connected to the chip 11. Here, the bow tie antennas 12 and 12 'are a pair of triangular pattern antennas disposed to face each other and are electrically connected to the chip 11 by conducting wires connected to the vertices facing each other.

Here, the feed point impedance may be adjusted by adjusting the height h and the angle θ of the triangular pattern antenna, and the impedance matching may be implemented by canceling the input reactance of the chip 11 according to the adjustment of the feed point impedance. .

U.S. Patent No. 6,265,977 discloses a radio frequency identification tag having first and second antenna elements, the first and second antenna elements having a bowtie pattern, and Japanese Patent No. 3,359,608 discloses the energy of an electromagnetic field. Disclosed is a contactless IC card system having a bowtie antenna as a means of receiving the same.

However, the tag having the bow tie antenna according to the prior art has a problem in that it is not easy to implement impedance matching between the chip and the bow tie antenna without a separate matching circuit.

That is, when designing an antenna for impedance matching, the loss impedance caused by not only the target impedance of the chip but also a complex factor, for example, the loss impedance generated during the mounting process between the chip and the antenna and the antenna according to the change of frequency Its own loss impedance must be taken into account, and the adjustment of the cabinet or height of the bowtie antenna alone has a limitation in canceling the reactance component and the lossy reactance component of the chip due to complex characteristic variations.

In addition, the bow tie antenna according to the prior art has a limitation in improving the characteristics of the matching reference bandwidth according to the antenna structure, and it is difficult to flexibly respond to the change of impedance due to the complex loss, which requires a lot of time and effort in the design. There is a problem.

The present invention has been made to solve the above problems, by improving the bowtie antenna geometry having a wide bandwidth, it is easy to match the impedance with the chip, the bowtie antenna with improved bandwidth characteristics, An object of the present invention is to provide a radio recognition tag and an impedance matching method using the same.

Bow tie-type antenna according to the present invention for achieving the above object, in the bow tie antenna provided in the tag, a pair of triangular pattern antenna having two sides and the bottom side forming a predetermined vertex angle are arranged opposite to each other. The triangular pattern antenna is characterized in that it comprises any one or more geometrical structures selected from slots, stubs or patches.

In the present invention, the slots are formed in equally spaced irregularities along two sides of the triangular pattern antenna, and the slots provided on each of the two sides are arranged in a zigzag pattern.

According to the present invention, the stub extends from both sides to be parallel or perpendicular to the base of the triangular pattern antenna, and the patch extends from the base of the triangular pattern antenna.

According to the present invention, the impedance of the triangular pattern antenna is adjusted according to the combination of the above geometric structures, the vertical distance from the base to the vertex, and the vertex angle.

According to another aspect of the present invention, a bow tie antenna having a pair of triangular pattern antennas having two sides and a bottom side constituting a predetermined angle is opposed to each other; And a tag chip electrically connected to the bowtie antenna, wherein the triangular pattern antenna includes at least one geometrical structure selected from slots, stubs, or patches so that the bowtie antenna can achieve impedance matching with the tag chip. It provides a radio recognition tag having a bow tie antenna, characterized in that.

Preferably, the impedance of the triangular pattern antenna is adjusted according to the combination of the geometry, the vertical distance from the base to the vertex, and the vertex angle, and the reactance component of the impedance cancels out from the reactance component of the tag chip.

According to another aspect of the present invention, a impedance matching method between a bow tie antenna having a pair of triangular pattern antennas having two sides and a bottom side forming a predetermined vertex and opposed to each other, and a tag chip electrically connected to the bow tie antenna (A) calculating an input impedance of a tag chip; And (B) adjusting a feed point impedance of the bowtie antenna so that the reactance component of the input impedance is cancelled, wherein the adjustment of the feed point impedance is a slot, stub or patch on the triangular pattern antenna. It provides an impedance matching method using a bow tie antenna, characterized in that it comprises one or more selected geometric structures.

In the present invention, the feed point impedance is adjusted according to the width, length, number and equal spacing of the slots formed in the shape of the unevenness at equal intervals along the two sides of the triangular pattern antenna.

In addition, the feed point impedance is adjusted according to the width and length of the stub extending from both sides to be parallel or perpendicular to the base of the triangular pattern antenna.

In addition, the feed point impedance is adjusted according to the area of the patch extending from the base of the triangular pattern antenna.

In addition, the feed point impedance is adjusted according to the vertical distance and the vertex angle from the base of the triangular pattern antenna to the vertex.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the present specification and claims should not be construed as being limited to the common or dictionary meanings, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, which can be replaced at the time of the present application It should be understood that there may be various equivalents and variations.

The bow tie antenna according to the present invention has a structure in which a slot, stub, or patch is selectively employed in a conventional bow tie antenna as shown in FIG. 3. Referring to 10, a bowtie-type antenna and a radio recognition tag including the bowtie-type antenna will be described.

First, a radio recognition tag having a bow tie antenna having a slot will be described with reference to FIG. 4.

As shown in FIG. 4, the RFID tag according to the first embodiment of the present invention includes a pair of triangular pattern antennas 110 and 110 ′ having slots 111 and 111 ′, and the triangular pattern antenna 110. And a tag chip 200 electrically connected to the 110 '.

Each of the triangular pattern antennas 110 and 110 ′ is electrically connected to a tag chip 200 that stores data about an object by a conductive wire. That is, one end forming one pole of the conductive wire is connected to the triangular pattern antenna 110 on one side, and the other end forming the other pole of the conductive wire is connected to the triangular pattern antenna 110 'on the other side.

The triangular pattern antennas 110 and 110 ′ have two sides and a bottom side constituting a predetermined vertex angle α, and slots 111 and 111 ′ are formed in equally spaced irregularities along the two sides.

In addition, the slots 111 and 111 ′ have a predetermined width, length, and number, and slots formed on one side of each of the triangular pattern antennas 110 and 110 ′ and slots formed on the other side are arranged in a zigzag pattern. Preferably, but not limited to.

In the first embodiment of the present invention, the impedance matching between the triangular pattern antennas 110 and 110 'and the tag chip 200 is made by canceling their mutual reactance, which is the triangular pattern antennas 110 and 110'. ), That is, by adjusting the width, length, number and equal spacing of the slots 111 and 111 'formed in the triangular pattern antennas 110 and 110'.

On the other hand, when adjusting the geometric structure, the impedance H is adjusted by adjusting the height H of the triangular pattern antennas 110 and 110 ', that is, the vertical distance from the base to the vertex, or by adjusting the vertex angle α. Although possible, it is obvious that the structural change of the slots 111 and 111 ′ is more advantageous in terms of the efficiency according to the manufacturing process and the design efficiency of the antenna.

In the first embodiment of the present invention, the triangular pattern antennas 110 and 110 'transmit and receive electromagnetic waves (RF) for transmitting and receiving data, and the electromagnetic wave received by the triangular pattern antennas 110 and 110' The rectifier circuit (not shown) converts the power into a DC power source, a predetermined voltage V _DC is applied across the conductive line, and the tag chip 200 is driven by the predetermined voltage.

Here, the feed point reactance component (+ jX) of the triangular pattern antennas 110 and 110 'is mutually canceled with the input reactance component (-jX) of the tag chip 200, and the triangular pattern antenna and the tag chip are canceled by the offset. Impedance matching is implemented between the two and transitions to the resonant frequency operating state according to the input electromagnetic waves.

In this case, the resonance frequency of the triangular pattern antennas 110 and 110 'may be adjusted by adjusting the geometric structure including the width, length, number and equal intervals of the slots 111 and 111', and adjusting the resonance frequency. According to the present invention, a miniaturized bow tie antenna can be implemented.

In addition, the adjustment of the geometric structure of the slots 111 and 111 ′ is easy to adjust the inductive reactance, so that the triangular pattern antennas 110 and 110 ′ in which the slots 111 and 111 ′ are formed are maintained in a wide band while maintaining miniaturization. It provides a stable bandwidth that does not affect impedance changes for wireless identification (RFID) systems.

Next, a radio recognition tag according to another embodiment of the present invention will be described with reference to FIGS. 5 and 10. In order to clarify the gist of the present invention in another embodiment of the present invention, the description overlapping with the above-described configuration and operation will not be described again, but a bowtie antenna including any one or more geometric structures selected from slots, stubs or patches. This section focuses on.

5 and 6 are plan views illustrating a radio recognition tag having a bow tie antenna having a stub according to a preferred embodiment of the present invention.

As shown in FIG. 5, the RFID tag according to the second embodiment of the present invention includes a pair of triangular pattern antennas 120 and 120 ′ having stubs 121 and 121 ′, and the triangular pattern antenna 120. , 120 ') and the tag chip 200 electrically connected thereto.

The triangular pattern antennas 120 and 120 ′ have stubs 121 and 121 ′ extending from two sides so as to be parallel to the base side, and the tag chip 200 is adjusted by adjusting the geometry of the stubs 121 and 121 ′. Impedance matching with can be achieved.

At this time, the geometric adjustment including the length, position and width of the stubs (121, 121 ') is easy to adjust the capacitive reactance, it is possible to adjust the resonant frequency of the triangular pattern antenna (120, 120'), According to the adjustment of the resonant frequency, a miniaturized bow tie antenna can be realized.

On the other hand, the radio recognition tag according to the third embodiment of the present invention shown in Figure 6 is a variation of the stub according to the second embodiment, the radio recognition tag is perpendicular to the base of the triangular pattern antenna (131, 131 ') Stubs 131 and 131 'are formed to extend in a shape surrounding both sides from both ends of the bottom side.

In the foregoing second and third embodiments, stubs are preferably opposed pairs, but not limited thereto. For example, a plurality of stubs spaced at equal intervals from two sides may be extended to be parallel or perpendicular to the base of the triangular pattern antenna.

FIG. 7 is a plan view illustrating a radio recognition tag having a bow tie antenna having a patch according to an exemplary embodiment of the present invention.

As shown in FIG. 7, the RFID tag according to the fourth embodiment of the present invention includes a pair of triangular pattern antennas 140 and 140 ′ having patches 141 and 141 ′, and the triangular pattern antenna 140. 140 ') and the tag chip 200 electrically connected thereto.

The triangular pattern antennas 140 and 140 ′ have patches 141 and 141 ′ extending from the bottom, and adjust the area of the patches 141 and 141 ′ to achieve impedance matching with the tag chip 200. Can be.

At this time, the geometrical adjustment including the areas of the patches 141 and 141 'is easy to adjust the inductive reactance.

8 and 9 are plan views illustrating a radio recognition tag including a bow tie antenna having slots and stubs formed therein.

As shown in FIGS. 8 and 9, the RFID tag according to the fifth and sixth embodiments of the present invention includes slots 151, 151 ′, 161, 161 ′ and stubs 152, 152 ′, 162 and 162. A pair of triangular pattern antennas 150, 150 ′, 160, 160 ′, and a tag chip 200 electrically connected to the triangular pattern antennas 150, 150 ′, 160, 160 ′. .

The triangular pattern antennas 150, 150 ′, 160, 160 ′ are slots 151, 151 ′, 161, 161 ′ formed at equal intervals along two sides, and stubs extending from two sides so as to be parallel or perpendicular to the base side. (152, 152 ', 162, 162') at the same time, and the tag chip by adjusting the geometry of the slots (151, 151 ', 161, 161') and stubs (152, 152 ', 162, 162') Impedance matching with 200 may be achieved.

At this time, the geometrical adjustment of the slots 151, 151 ', 161, 161' and the stubs 152, 152 ', 162, and 162' makes it easy to adjust the inductive and capacitive reactances.

FIG. 10 is a plan view illustrating a radio recognition tag having a bow tie antenna having a slot and a patch formed therein. FIG.

As shown in FIG. 10, the RFID tag according to the seventh embodiment of the present invention includes a pair of triangular pattern antennas 170 and 170 ′ in which slots 171 and 171 ′ and patches 172 and 172 ′ are formed. And a tag chip 200 electrically connected to the triangular pattern antennas 170 and 170 '.

The triangular pattern antennas 170 and 170 'are provided with slots 171 and 171' formed at equal intervals along two sides and patches 172 and 172 'extending from the bottom side. 171 ') and the stubs 172 and 172' can be adjusted to achieve impedance matching with the tag chip.

At this time, the geometrical adjustment of the slots 171 and 171 'and the stubs 172 and 172' makes it easy to adjust the inductive reactance.

As described above, the triangular pattern antenna of the radio recognition tag according to the first to seventh embodiments of the present invention includes any one or more geometric structures selected from slots, stubs, or patches, and the tag according to the structural adjustment of the geometric structures. Impedance matching with a chip may be implemented. Referring to the fifth embodiment shown in FIG. 8, the impedance matching method between the bow tie antenna and the tag chip will be described as follows.

Referring to FIG. 8, first, an input impedance of the tag chip 200 is calculated. In this case, it is obvious that the loss impedance including the process loss is considered in addition to the input impedance of the tag chip 200 when calculating the input impedance.

Next, in order to cancel the inductive and capacitive reactance components of the input impedance, the geometry of the slots 151 and 151 'and the stubs 152 and 152' formed in the triangular pattern antennas 150 and 150 'are adjusted. do.

In more detail, the width, length, number and equal intervals of the slots 151 and 151 'are adjusted, or the length and width of the stubs 152 and 152' are adjusted, and the triangular pattern according to the adjustment is performed. The feed point reactance component (+ jX) of the antennas 150 and 150 'is offset by the input reactance component (-jX) of the tag chip 200.

In this case, when the inductive reactance component of the input reactance component is large, the geometry of the slots 151 and 151 'is adjusted, and when the capacitive reactance component is large, the geometry of the stubs 152 and 152' is adjusted. Impedance matching is implemented between the triangular pattern antennas 150 and 150 ′ and the tag chip 200.

As described above, the bow tie antenna according to the embodiment of the present invention is improved in its geometry, and it is possible to reduce the size and the size of the radio recognition tag without adjusting the cabinet and height, and to maintain the weight and size of the radio recognition tag with the tag chip. It facilitates impedance matching and enables stable resonance frequency operation without affecting impedance changes in wideband.

Although the present invention has been described above by means of limited embodiments and drawings, the present invention is not limited thereto and will be described below by the person skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of the claims.

As described above, according to the present invention, by selectively employing slots, stubs or patches in the bowtie antenna to improve its geometric structure, impedance matching between the chip and the antenna is easy, an appropriate bandwidth can be secured, and separate matching is possible. There is an advantage that can contribute to the miniaturization of the radio tag without a circuit.

In addition, the present invention can flexibly respond to the change in impedance due to the complex characteristic deviation loss can improve the design efficiency of the antenna.

Claims (17)

In the bow tie antenna provided in the radio tag, A pair of triangular pattern antennas having two sides and a bottom side forming a predetermined vertex are arranged opposite to each other, wherein the triangular pattern antenna comprises at least one geometric structure selected from slots, stubs or patches. The method of claim 1, The slot is a bow tie-type antenna, characterized in that formed along the two sides of the triangular pattern antenna in the shape of irregularities of equal intervals. The method of claim 2, Slots provided on each of the two sides are bow tie-type antenna, characterized in that arranged in a zigzag pattern. The method of claim 1, The stub extends from two sides to be parallel or perpendicular to the base of the triangular pattern antenna. The method of claim 1, The patch is a bow tie antenna, characterized in that formed extending from the base of the triangular pattern antenna. The method of claim 1, Bow tie type antenna, characterized in that the impedance of the triangular pattern antenna is adjusted according to the combination of the geometric structure, the vertical distance from the base to the vertex, and the vertex angle. A bow tie antenna in which a pair of triangular pattern antennas having two sides and a bottom side forming a predetermined vertex are disposed to face each other; And Including a tag chip electrically connected to the bow tie antenna, And the triangular pattern antenna includes one or more geometric structures selected from slots, stubs, or patches so that the bowtie antenna can achieve impedance matching with a tag chip. The method of claim 7, wherein The impedance of the triangular pattern antenna is adjusted according to the combination of the geometric structure, the vertical distance from the base to the vertex, and the vertex angle, and the reactance component of the impedance is canceled from the reactance component of the tag chip. Wireless identification tag provided with tena. The method of claim 7, wherein The slot is a radio recognition tag, characterized in that formed in the irregular shape of the equal intervals (따라) along the two sides of the triangular pattern antenna. The method of claim 9, Slots provided on each of the two sides is a radio recognition tag having an ultra-wideband antenna, characterized in that arranged in a zigzag pattern. The method of claim 7, wherein The stub extends from both sides to be parallel or perpendicular to the base of the triangular pattern antenna, the RFID tag. The method of claim 7, wherein The patch is a radio recognition tag, characterized in that extending from the base of the triangular pattern antenna. A impedance matching method between a bow tie antenna having a pair of triangular pattern antennas having two sides and a bottom side forming a predetermined vertex opposite to each other, and a tag chip electrically connected to the bow tie antenna, (A) calculating the input impedance of the tag chip; And (B) adjusting a feed point impedance of the bowtie antenna such that the reactance component of the input impedance is cancelled; Adjusting the feed point impedance is impedance matching method using a bow tie antenna, characterized in that the triangular pattern antenna including any one or more of the geometric structure selected from the slot, stub or patch. The method of claim 13, The feed point impedance is adjusted according to the width, length, number and equal intervals of the slots formed in the irregular shape of the equal interval along the two sides of the triangular pattern antenna impedance matching method using a bow tie-type antenna. The method of claim 13, The feed point impedance is adjusted according to the width and length of the stub extending from the two sides to be parallel or perpendicular to the base of the triangular pattern antenna impedance matching method using a bow tie antenna. The method of claim 13, The feed point impedance is impedance matching method using a bow tie antenna, characterized in that adjusted according to the area of the patch extending from the base of the triangular pattern antenna. The method of claim 13, The feed point impedance is adjusted according to the vertical distance from the bottom of the triangular pattern antenna to the vertex and the vertex angle, impedance matching method using a bow tie antenna.

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