WO2007017944A1

WO2007017944A1 - Antenna

Info

Publication number: WO2007017944A1
Application number: PCT/JP2005/014690
Authority: WO
Inventors: Hisao Tanabe
Original assignee: Hitachi, Ltd.
Priority date: 2005-08-10
Filing date: 2005-08-10
Publication date: 2007-02-15
Also published as: JPWO2007017967A1; WO2007017967A1; TW200707306A

Abstract

A technique for expanding the use range of an antenna for an RFID by extending the communication distance of the antenna. A two-element antenna (1) is constituted by placing an antenna (13) in parallel to or at an angle other than right angle to a dipole antenna (12) that is connected to an RFID chip (11) and is resonant to the communication carrier frequency. The dipole antenna (12) has a length in the range from λ/2 to λ/3, preferably λ/2.3 or thereabout. The antenna (13) has a length in the range from λ/2 to λ/4, preferably λ/2.8 or thereabout. Combination angle of the dipole antenna (12) and the antenna (13) is in the range from 45˚ to 85˚, preferably 80˚ or thereabout.

Description

Specification

Antenna

Technical field

[0001] The present invention relates to an antenna, and more particularly to a technique effective when applied to an antenna for RFID (Radio Frequency Identification).

Background art

[0002] As a technique examined by the present inventors, for example, the following techniques are conceivable in RFID.

[0003] A system using RFID will be described as an example of using a wireless communication device. A system using RFID is composed of an interrogator having a read or read / write function and a responder called a wireless tag. In recent years, batteryless tags that detect transmission radio waves from interrogators and use them as drive power have appeared, and various applications are being studied in many fields.

[0004] In addition, since a system using RFID can be easily configured, it can automatically manage or sort items such as product management in a production line or warehouse or store, automatic sorting of items, postal delivery, and home delivery. A wide range of distribution / distribution fields such as classification confirmation, etc. are being considered for application in these fields.

[0005] Further, Patent Document 1 discloses an article management system as shown in FIG. In this system, the common radio wave reflector 94 is separated from the wireless tag 93 by a distance L in parallel with the wireless tag 93 as a responder. As a result, the signal from the interrogator is reflected by the common radio wave reflector 94, thereby increasing the electric field strength of the radio wave to the radio tag 93 as the responder.

Patent Document 1: Japanese Patent Laid-Open No. 2004-250185

Disclosure of the invention

Problems to be solved by the invention

[0006] By the way, as a result of the study of the present inventors by the RFID technology as described above, the following has become clear. [0007] Wide range of distribution and logistics fields, such as product management in production lines or warehouses, stores, etc., automatic sorting of goods, automatic sorting of mail delivery and home delivery, etc. When a wireless tag is attached and used, the communication distance is often insufficient with a conventional wireless tag.

Accordingly, an object of the present invention is to provide a technology capable of extending the communication range and expanding the range of use in an RFID antenna.

[0009] The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

Means for solving the problem

[0010] Among the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

That is, the antenna according to the present invention has a shape in which a dipole antenna, which is a first antenna, is combined with a second antenna having an angle that is not parallel or perpendicular. The first antenna and the second antenna that are combined may be insulated or integrated.

[0012] In addition, the dipole antenna, which is the first antenna, is combined with a second antenna that is not parallel or at a right angle but a third antenna that is parallel to the first antenna. The first antenna, the second antenna, and the third antenna that are combined may be all insulated or may be partly or entirely integrated.

[0013] In addition, the first antenna that is a loop antenna and the second antenna that is not parallel or at a right angle but a certain angle are combined in a supply line on which RFID is mounted.

[0014] Further, a signal is supplied by providing a supply line on which RFID is mounted inside the loop antenna which is the first antenna.

The invention's effect

[0015] The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described as follows.

[0016] The communication distance of the antenna can be extended.

Brief Description of Drawings FIG. 1 is a plan view showing the shape of a two-configuration antenna according to Embodiment 1 of the present invention.

FIG. 2 is a diagram showing a measurement result of a two-configuration antenna according to Embodiment 1 of the present invention.

FIG. 3 is a plan view showing the shape of a three-configuration antenna according to Embodiment 2 of the present invention.

FIG. 4 is a diagram showing a measurement result of a three-configuration antenna according to Embodiment 2 of the present invention.

FIG. 5 is a plan view showing a shape of a modified loop antenna according to a third embodiment of the present invention.

FIG. 6 is a diagram showing a measurement result of the modified loop antenna according to the third embodiment of the present invention.

FIG. 7 is a plan view showing the shape of a supply antenna in a loop antenna according to a fourth embodiment of the present invention.

[Fig. 8] Fig. 8 is a diagram showing a measurement result of a supply antenna in a loop antenna according to a fourth embodiment of the present invention.

FIG. 9 is a diagram showing a basic configuration of an RFID system to which an antenna according to the present invention is applied.

FIG. 10 is a perspective view showing an antenna configuration of the article management system disclosed in Patent Document 1.

[FIG. 11] (1) to (5) are diagrams showing a manufacturing method of a two-configuration antenna having an insulating structure in the first embodiment of the present invention.

[FIG. 12] (1) to (3) are diagrams showing a method for manufacturing an integral two-component antenna in the first embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.

FIG. 9 shows a basic configuration of a system using RFID to which the antenna according to the present invention is applied. The system using RFID includes an interrogator 91, an antenna 92, and a wireless tag (RFID tag) 93 using a dipole antenna. The signal from the interrogator 91 is transmitted as a radio wave from the antenna 92 connected to the interrogator 91. The signal transmitted from the antenna 92 is received by the antenna of the wireless tag 93 existing in the radio wave area. The radio tag 93 detects the received signal, operates the RFID internal circuit as an internal power source, Information written inside is transmitted as radio waves. The signal transmitted from the wireless tag 93 is received by the antenna 92 of the interrogator 91, and the HD information is demodulated.

[0020] The wireless tag 93 is also configured with force such as an RFID chip and an antenna. The antenna applied to this wireless tag will be described below.

[0021] (Embodiment 1)

FIG. 1 is a plan view showing the shape of a two-configuration antenna according to the first embodiment of the present invention, and FIG. 2 is a diagram showing the measurement results of the two-configuration antenna according to the first embodiment.

[0022] First, an example of the configuration of a two-configuration antenna according to Embodiment 1 will be described with reference to FIG. The two-configuration antenna 1 of the first embodiment is, for example, an RFI D antenna that transmits and receives circularly polarized radio waves, and includes a dipole antenna (first antenna) 12 and an antenna (second antenna) 13. The force is composed.

In FIG. 1, a two-configuration antenna 1 has a shape in which an antenna 13 is arranged at an angle other than parallel or perpendicular to a dipole antenna 12 connected to an RFID chip 11 and resonating with a communication carrier frequency. At this time, the dipole antenna 12 and the antenna 13 may be insulated or may be integrated. The material of the dipole antenna 12 and the antenna 13 is aluminum, copper or the like.

The antenna 13 serves as a director in the Yagi antenna. When a conductor is placed in an electromagnetic field, current is induced and radiated without direct power supply. This is called a non-powered element and is practically used as a director or reflector. The director has a conductor that is shorter than half the wavelength of the communication carrier frequency. A current with a phase lag is excited in this conductor, and the current that is also emitted from this conductor is in phase with the initial current.

[0025] The antenna of the present invention uses circularly polarized waves. When circularly polarized waves are fed to two orthogonal antennas with a phase difference of 90 degrees, both electromagnetic waves and electric fields change with time. This is called circular polarization because the locus of the electric field is a circle. The operation when the direction of rotation of the circularly polarized wave, which is also transmitted by the interrogator antenna, is clockwise is explained. The circularly polarized signal 14 transmitted from the interrogator antenna is amplified by the antenna 13, and the amplified signal wave 14a is received by the dipole antenna 12. Become.

[0026] Antenna force on the interrogator side This is implemented when the direction of rotation of the transmitted circularly polarized wave is counterclockwise The same function can be achieved by arranging the two-configuration antenna 1 according to the form 1 in the inside out. Therefore, when adopting the antenna of the present invention, it is only necessary to prepare two types of tags, face up and inside out, and decide which one to use depending on the rotation direction of the circular polarization of the interrogator used.

[0027] The length (L) of the dipole antenna 12 is preferably around λ / 2.3 in the range of λΖ2 to λ / 3, assuming the wavelength of the communication carrier. This is determined by the shortening rate due to the effect of the dielectric constant of the film because the dipole antenna is deposited on the film, and λ Ζ2 when an epoxy resin composition film with a dielectric constant of 1.96 is adopted. . 3 Therefore, for example, when an RFID chip having a chip size of 0.5 mm square or less is used, the length of the dipole antenna 12 is 52 mm.

[0028] The length (L) of the antenna 13 is preferably about λ / 2.8 in the range of λΖ2 to λ 前後 4.

2

Therefore, for example, when an RFID chip having a chip size of 0.5 mm square or less is used, it is 40 mm.

[0029] The combined angle (Θ) of the dipole antenna 12 and the antenna 13 is in the range of 45 to 85 degrees, and is preferably around 80 degrees. The basis for these numbers is explained using Figure 2.

FIG. 2 shows a measurement result when an RFID chip having a feature that the chip size of the two-configuration antenna 1 according to the first embodiment is 0.5 mm square or less is used. The communication distance 26, which is the measurement result of the two-component antenna in a configuration in which the dipole antenna 12 and the antenna 13 are insulated, represents the distance from the antenna on the interrogator side to the wireless tag (two-component antenna 1), and the unit is cm (centimeter). Angle 27 indicates the angle (Θ) between the dipole antenna 12 and the antenna 13, and the left force is 90 degrees, 80 degrees, 70 degrees, 60 degrees, 50 degrees, and 40 degrees.

[0031] The unit characteristic 21 shows the result of measuring the dipole antenna 12 alone. From the scale of the communication distance 26, the performance of the dipole antenna 12 alone is 68cm.

[0032] Antenna length 50 mm (millimeter) Characteristic 22 is that the length (L) of the antenna 13 is λ / 2.

2

= Shows the measurement result when 50mm. From this result, the length (L) of the antenna 13 is When λ / 2.4 = 50 mm, the communication distance force is 92 cm between the angle (0) and 80 degrees, indicating that the characteristics are good.

[0033] Similarly, in the antenna length (L) 45mm characteristic 23, the point where the angle (0) is 80 degrees is 98cm,

twenty one

For antenna length (L) 40mm characteristic 24, the point where the angle (Θ) is 80 degrees shows the maximum value of 98cm.

twenty one

In the case of antenna length (L) 35mm characteristic 25, the point where the angle (Θ) is 80 degrees is 82cm.

twenty one

The separation is falling.

[0034] Due to the above, the length (L) of the antenna 13 is 45mm (Z2.7) force 40mm (Z

2

In 3), the combination angle (Θ) between the dipole antenna 12 and the antenna 13 should be around 80 degrees.

FIG. 11 shows a manufacturing method of the two-configuration antenna 1 when the dipole antenna 12 and the antenna 13 are insulated. The two-configuration antenna 1 is manufactured in the following order of steps (1) to (5).

(1) The dipole antenna 12 is deposited on the film 15. (2) Connect the RFID chip 11 to the dipole antenna 12. (3) Apply the insulating film 16 to the dipole antenna 12. (

4) The antenna 13 is deposited. (5) The insulating film 17 is applied to the antenna 13 to complete. In the case of this method, the manufacturing unit price increases due to the increased number of processes. If you want to manufacture at a low cost, the communication distance will be slightly reduced, but it is desirable to have an integrated structure.

FIG. 12 shows a manufacturing method of the two-component antenna 1 when the dipole antenna 12 and the antenna 13 are manufactured in an integral structure. The two-piece antenna 1 with a single structure has the following (1) to (3

) In the order of processes.

(1) A monolithic antenna 18 of a dipole antenna 12 and an antenna 13 is deposited on the film 15. (2) —Connect RFID chip 11 to body structure antenna 18. (3) —The insulating film 19 is applied to the body structure antenna 18 to complete.

Therefore, according to the antenna of the first embodiment, a communication distance of about 1.4 times that of the conventional antenna can be obtained.

[0040] (Embodiment 2)

FIG. 3 is a plan view showing the shape of the three-configuration antenna according to the second embodiment of the present invention, and FIG. 4 is a diagram showing the measurement results of the three-configuration antenna according to the second embodiment. First, referring to FIG. 3, an example of the configuration of a three-configuration antenna according to the second embodiment will be described. The three-configuration antenna 3 of the second embodiment is, for example, an RFI D antenna that transmits and receives circularly polarized radio waves, and includes a dipole antenna (first antenna) 12 and an antenna (second antenna) 13. The parallel antenna (third antenna) 31 is configured.

[0042] In Fig. 3, the three-configuration antenna 3 is configured such that an antenna 13 is disposed at an angle not parallel or perpendicular to a dipole antenna 12 connected to the RFID chip 11 and resonating with a communication carrier frequency. The shape consists of a parallel antenna 31 parallel to the dipole antenna 12. At this time, the dipole antenna 12, the antenna 13, and the parallel antenna 31 may be insulated or partially integrated. Here, the partially integrated structure means that the dipole antenna 12 and the antenna 13 or the antenna 13 and the parallel antenna 31 are integrated.

[0043] In the case of insulation, the manufacturing method of the three-component antenna 3 is the same as that of the two-component antenna according to the first embodiment, in which a dipole antenna 12 is vapor-deposited on a substrate or a film and an insulating film is applied. Then, the antenna 13 is vapor-deposited, and then an insulating film is applied, and then the parallel antenna 31 is vapor-deposited. In this case, since the number of processes increases, the manufacturing unit price increases. Therefore, if you want to manufacture at a low cost, the communication distance will be slightly reduced, but it is desirable to have an integrated structure. In the case of an integrated structure, the dipole antenna 12 and the antenna 13, or the antenna 13 and the parallel antenna 31 are combined, or the dipole antenna 12, the antenna 13 and the parallel antenna 31 are combined. Vapor deposition may be performed on a substrate or a film.

The length (L) of the dipole antenna 12 is preferably about λ / 2.3 in the range of λ 2 to λ 3. This is determined by the shortening rate due to the influence of the dielectric constant of the film because the dipole antenna is deposited on the film. When an epoxy resin composition film with a dielectric constant of 1.96 is used, λ Ζ2 . 3

[0045] The length (L) of the antenna 13 is preferably in the range of λ Ζ2 to λ Ζ4 and around λ /2.8. Yo

2

[0046] The combination angle (Θ) between the dipole antenna 12 and the antenna 13 ranges from 55 degrees to 85 degrees. Around 80 degrees is desirable. The values of the length of dipole antenna 12 (L and the length of antenna 13 (L), and the combined angle of dipole antenna 12 and antenna 13 (Θ))

The basis for 2 1 is the same as the explanation using Figure 2 above.

[0047] The three-component antenna of the second embodiment is a combination of the two-component antenna and a parallel antenna 31. The length (L) of the parallel antenna 31 is in the range of λ Ζ2 to λ Ζ3

Three

Therefore, around λ 前後 2.4 is desirable. The rationale for this figure is explained using Figure 4.

FIG. 4 shows a measurement result when an RFID chip having a feature that the chip size of the three-configuration antenna 3 of the second embodiment is 0.5 mm square or less is used. This is a measurement result of a three-component antenna in a configuration in which a dipole antenna 12, an antenna 13, and a parallel antenna 31 are insulated. The communication distance 26 represents the distance from the interrogator antenna to the wireless tag (3 antennas 3), and the unit is cm. The unit characteristic 21 shows the measurement result of the dipole antenna 12 alone. From the scale of the communication distance 26, the performance of the dipole antenna 12 alone is 68 cm. The dual antenna characteristic 41 shows the optimum value with the dual antenna described in FIG. 2, and is 98 cm from the scale of the communication distance 26.

[0049] The length (L) 44 of the parallel antenna 31 is of two types, L = 50mm and L = 45mm. Horizontal

3 3 3

A position (Dx) 45 indicates a lateral distance between the dipole antenna 12 and the parallel antenna 31. A vertical position (Dy) 46 indicates a vertical distance between the dipole antenna 12 and the parallel antenna 31. The parallel antenna 50mm characteristic 42 indicates that the length (L) of the parallel antenna 31 is

Three

The measurement result at 50 mm is shown. From this measurement result, the position of the parallel antenna 31 from the dipole antenna 12 is 30 mm and 40 mm in the horizontal direction (Dx), and the communication distance force is 104 cm at the position of the vertical position (Dy) force S 30 mm. The parallel antenna 45 mm characteristic 43 shows the measurement result when the length (L) of the parallel antenna 31 is 45 mm. This measurement

Three

The results show that the parallel antenna 31 has a length (L) force of S50mm and a lateral (Dx) force of S30mm and 40mm.

Three

In mm, the vertical position (Dy) is 30 mm.

[0050] Therefore, according to the antenna of the second embodiment, a communication distance of about 1.5 times that of the conventional antenna can be obtained.

[0051] (Embodiment 3) FIG. 5 is a plan view showing the shape of the modified loop antenna according to the third embodiment of the present invention, and FIG. 6 is a diagram showing the measurement results of the modified loop antenna according to the third embodiment.

First, an example of the configuration of the modified loop antenna according to the third embodiment will be described with reference to FIG. The modified loop antenna 5 of the third embodiment is, for example, an RFID antenna that transmits and receives circularly polarized radio waves, and includes a loop antenna (first antenna) 51, an antenna (second antenna) 52, and a supply line. It is composed of 53 forces.

In FIG. 5, the modified loop antenna 5 is connected by a supply line 53 that connects a loop antenna 51 that resonates with a communication carrier frequency and an antenna 52 that is arranged at an angle that is not parallel or perpendicular to the RFID chip 11. It has a shape. The size of the loop antenna 51 is λ 横 6 in the horizontal (Lx) and λΖ4 in the vertical (Ly). The length (L) of the antenna 52 is λ

4 Ζ

In the range of 2 to λ Ζ3, around λ Ζ2.4 is desirable. In addition, the angle (Θ) between the supply line 53 and the antenna 52 is in the range of 30 to 60 degrees, and a position of 40 degrees or 60 degrees from the 35 degrees force is desired.

2

Good. The basis for this angle will be explained with reference to FIG.

FIG. 6 shows the measurement results of the modified loop antenna of the third embodiment. The communication distance 26 represents the distance from the antenna on the interrogator side to the wireless tag (modified loop antenna 5), and the unit is cm. The unit characteristic 21 shows the result of measurement with the dipole antenna 12 alone, and the communication distance is 68 cm. The angle (Θ) 62 depends on the supply line 53 and the key

2

The angle of the antenna 52 was shown, and the 30 degree force was also measured in the 60 degree range. However, since measurement data was not obtained at the 30 degree position, the 35 degree position was measured and tracked. At this time, the loop antenna 51 and the antenna 52 overlap each other at a position of 30 degrees. From the measurement result 61 of this deformed loop antenna, the angle (Θ) is 35 degrees, force is 40 degrees, or 60 degrees.

2

The communication distance is 94cm, which is the best point.

[0055] Therefore, according to the antenna of the third embodiment, a communication distance of about 1.4 times that of the conventional antenna can be obtained.

[Embodiment 4]

FIG. 7 is a plan view showing the shape of the antenna supplied in the loop antenna according to the fourth embodiment of the present invention, and FIG. 8 is a diagram showing the measurement result of the antenna supplied in the loop antenna according to the fourth embodiment. First, an example of the configuration of the supply antenna in the loop antenna according to the fourth embodiment will be described with reference to FIG. The supply antenna 7 in the loop antenna according to the fourth embodiment is, for example, an RFID antenna that transmits and receives circularly polarized radio waves, and includes a force such as a loop antenna (first antenna) 51 and a supply line 72. Yes.

In FIG. 7, the supply antenna 7 in the loop antenna has a shape in which a supply line 72 attached with the RFID chip 11 is connected to the inside of the loop antenna 71. The vertical length (Ly) is fixed at 60mm, which is λΖ2, but the horizontal length (Lx) is in the range of λΖ6 to λΖ3. Adjust line position (L) 73

6 Supply line position (L) 73 is in the range of λ Ζ2.4 to λ Ζ3, for example,

6

When using an RFID chip whose size is less than 0.5 mm square, a position of 42.5 mm around λ Ζ2.8 is desirable. The rationale for this figure is explained using Figure 8.

[0059] FIG. 8 shows the measurement results when the RFID chip having the feature that the chip size of the antenna supplied in the loop antenna of the fourth embodiment is 0.5 mm square or less is used. The communication distance 26 represents the distance from the antenna on the interrogator side to the wireless tag (supplied antenna 7 in the loop antenna), and its unit is cm. The unit characteristic 21 shows the result of measurement with the dipole antenna 12 alone, and the communication distance is 68 cm. The supply line position 82 indicates the measured position of the supply line position (L) 73 shown in FIG. loop

6

From the antenna measurement result 81 in the antenna, the position of the supply line (L) is about 42.5 mm.

6

It can be seen that the communication distance force at the place is 112cm, the highest point.

[0060] Therefore, according to the antenna of the fourth embodiment, a communication distance of about 1.6 times that of the conventional antenna can be obtained.

[0061] While the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. It's possible that it's possible!

[0062] For example, in the above-described embodiment, the force described for RFID is not limited to this, and can be applied to antennas of other communication systems.

Industrial applicability

[0063] A system using RFID to which the antenna according to the present invention is applied has a simple configuration. Wide range of distribution and logistics fields such as product management, automatic sorting of goods, automatic sorting of mail delivery and home delivery, etc., or confirmation of sorting classification in production lines or warehouses and stores! Application in the field is being considered!

Claims

The scope of the claims

[1] a linear first antenna;

A linear second antenna that is shorter than the first antenna,

An angle formed by the first antenna and the second antenna is not parallel or perpendicular.

[2] The antenna according to claim 1,

The antenna is an RFID antenna used for RFID communication, wherein the first antenna has a shape that resonates with the RFID communication carrier frequency.

[3] The antenna according to claim 2,

The antenna is characterized in that the first antenna and the second antenna are non-contact.

[4] The antenna according to claim 2,

The antenna characterized in that the first antenna and the second antenna have an integral structure.

[5] The antenna according to claim 2,

The length of the first antenna is λ Ζ3 or more and λ Ζ2 or less with reference to the wavelength of the RFID communication carrier wave,

The length of the second antenna is λ Ζ4 or more and λ Ζ2 or less,

An angle between the first antenna and the second antenna is 45 degrees or more and 85 degrees or less.

[6] The antenna according to claim 2,

The length of the first antenna is approximately λ / 2.3 based on the wavelength of the RFID communication carrier wave,

The length of the second antenna is approximately λΖ2.8.

An angle between the first antenna and the second antenna is approximately 80 degrees.

[7] The antenna according to claim 1, The antenna further comprises a linear third antenna arranged parallel to the first antenna and shifted in the longitudinal direction.

[8] The antenna according to claim 7,

The antenna is an RFID antenna used for RFID communication, wherein the first antenna and the second antenna have a shape that resonates with the RFID communication carrier frequency.

[9] The antenna according to claim 8,

The antenna, wherein the first antenna, the second antenna, and the third antenna are non-contact with each other.

[10] The antenna according to claim 8,

At least two or more of the first antenna, the second antenna, and the third antenna have an integral structure.

[11] The antenna according to claim 8,

The length of the second antenna is λ Ζ4 or more and λ Ζ2 or less,

The length of the third antenna is not less than λΖ3 and not more than λλ2.

An angle between the first antenna and the second antenna is 55 degrees or more and 85 degrees or less.

[12] The antenna according to claim 8,

The length of the second antenna is approximately λΖ2.8.

The length of the third antenna is approximately λΖ2.4.

[13] a loop-shaped first antenna;

A linear second antenna; An antenna having a supply line connecting the first antenna and the second antenna, and an angle formed by the first antenna and the second antenna is not parallel or perpendicular. .

[14] The antenna of claim 13,

The antenna is an RFID antenna used for RFID communication, and the first antenna and the second antenna have a shape that resonates with a communication carrier frequency of the RFID,

An antenna, wherein an RFID chip is mounted on the supply line.

[15] The antenna of claim 14,

The length of the first antenna is approximately λΖ6 in the horizontal direction and approximately λΖ4 in the vertical direction with reference to the wavelength λ of the RFID communication carrier wave,

The length of the second antenna is λλ3 or more and λΖ2 or less,

An angle between the supply line and the second antenna is 30 degrees or more and 60 degrees or less.

[16] The antenna of claim 14,

The length of the second antenna is approximately λΖ2.4.

An angle between the supply line and the second antenna is 35 degrees or more and 60 degrees or less.

[17] a loop-shaped first antenna;

A supply line connected to the first antenna;

The antenna, wherein the supply line is inside the first antenna.

[18] The antenna of claim 17,

The antenna is an RFID antenna used for RFID communication, and the first antenna has a shape resonating with the RFID communication carrier frequency, and an RFID chip is mounted on the supply line An antenna characterized by that.

[19] The antenna of claim 18, The length of the first antenna is λ Ζ6 or more and λ 搬送波 3 or less in the horizontal direction and λ Ζ2 in the vertical direction based on the wavelength λ of the communication carrier wave of the RFID,

The antenna is characterized in that the position of the supply line is such that the distance from the upper end of the first antenna is λλ3 or more and λ / 2.4 or less.

The antenna of claim 18,

The length of the first antenna is λ Ζ6 or more and λ Ζ3 or less in the horizontal direction and λ Ζ2 in the vertical direction based on the wavelength λ of the communication carrier wave of the RFID,

The antenna is characterized in that the position of the supply line is approximately λΖ2.8 from the upper end of the first antenna.