JP2011049935A - Antenna device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna device having proper communication performance, regardless of the distance between an antenna and a metallic body. <P>SOLUTION: The antenna device includes a loop-like antenna 1, a metallic body 6 prepared on one surface of an opening surface of the loop-like antenna 1, and a coil 2 inserted into a line of the loop-like antenna 1. The coil axis of the coil 2 is characterized in that it is parallel to the opening surface of the loop-like antenna 1, but non-parallel to the direction of current flowing through front and back of a section where the coil 2 is inserted into the line of the loop-like antenna 1. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an RF-ID, that is, a wireless communication medium processing apparatus that performs communication with a wireless communication medium such as an IC card or an IC tag, or an antenna apparatus used for the wireless communication medium itself.

  In recent years, mobile terminals such as mobile phones that have built-in RF-ID wireless tags and those that have a function of reading non-contact IC cards and IC tags have become widespread. An antenna device in which a magnetic sheet is bonded (the coil axis of a loop-shaped antenna is perpendicular to the magnetic sheet) is often used.

  However, when the metal body is close to the back surface of the antenna, the communication performance is likely to deteriorate, and if the magnetic sheet is thickened to prevent this, the miniaturization / thinning of the portable terminal is hindered.

  In view of this, an antenna device using a coil having a coil axis horizontal to an adjacent metal surface has been devised, such as (Patent Document 1) focusing on the magnetic field distribution in the vicinity of the metal body.

JP 2008-048376 A

  However, since the structure of (Patent Document 1) uses a coil having a coil axis that is horizontal to the metal surface, the communication performance when not close to the metal body is magnetic on the opening surface of the loop antenna. It is inferior compared with the thing using the conventional antenna which bonded the body sheet. For this reason, if the planned antenna mounting location is changed due to a design change, etc., the same antenna cannot be used, resulting in problems such as the need to redo the selection of the antenna, which hinders development. There is a fear.

  In view of the above problems, an object of the present invention is to provide an antenna device having good communication performance regardless of the distance between the antenna and the metal body.

In order to solve the above problems, the present invention includes a loop-shaped antenna and a coil inserted in a line of the loop-shaped antenna, and the coil has a coil axis that is an opening surface of the loop-shaped antenna. And an antenna device characterized by being non-parallel to the direction of the current flowing through the portion before and after the loop antenna line coil is inserted.

  ADVANTAGE OF THE INVENTION According to this invention, the antenna apparatus which has favorable communication performance can be provided irrespective of the distance of an antenna and a metal body.

The conceptual diagram of the antenna apparatus in the Example of this invention The conceptual diagram of the antenna apparatus in the Example of this invention The conceptual diagram of the antenna apparatus in the Example of this invention Conceptual diagram of the present invention when transmitting from an antenna when a metal object is in a distance Conceptual diagram of the present invention when the antenna is subjected to a magnetic field from the outside when the metal body is far away Conceptual diagram of the present invention when transmitting from an antenna when a metal body is in the vicinity Conceptual diagram of the present invention when an antenna receives a magnetic field from the outside when a metal body is in the vicinity Conceptual diagram of a conventional example when transmitting from an antenna when a metal body is in the vicinity Conceptual diagram of a conventional example when a metal body is in the vicinity and the antenna receives a magnetic field from the outside Conventional view when placed close to a metal body Conceptual diagram of an embodiment of the present invention Perspective view when the mobile terminal is disassembled Conceptual diagram of conventional antenna device Experiment result graph of distance to substrate and magnetic field strength Experimental result graph of angle and magnetic field strength Conceptual diagram of the antenna device of the present invention in an experiment Conceptual diagram of conventional example in experiment Image of communication between terminals Result graph of winding number experiment Conceptual diagram of an embodiment of the present invention

  According to the invention described in claim 1 of the present invention, it is provided with a loop-shaped antenna and a coil inserted into a line of the loop-shaped antenna, and the coil has a coil axis that is a loop-shaped antenna. The antenna device is characterized by being parallel to the opening surface of the antenna and being non-parallel to the direction of the current flowing through the portion before and after the loop antenna line coil is inserted. An antenna device having good communication performance can be provided regardless of the distance of the body.

  According to the invention described in claim 2 of the present invention, in the antenna device according to claim 1, by providing a plurality of coils in the loop-shaped antenna, an eddy current generated in the metal body by the plurality of coils arranged can be reduced. Since it can be used efficiently, an antenna device having good communication performance can be provided even when the metal body is close.

  According to a third aspect of the present invention, in the antenna device according to the first aspect, the number of turns of the conductor constituting the coil is approximately half or more than an integral multiple, so that the coil terminal is Since it can be provided at both ends of the coil, it can be easily inserted into the line constituting the loop antenna.

  According to a fourth aspect of the present invention, in the antenna device according to the third aspect, the number of conductors wound around the metal body side surface of the coil is opposite to the metal body side surface. Since the number of conductors wound on the surface of the coil is smaller than the number of conductors, the coil can efficiently create a magnetic field and can efficiently capture the magnetic field.

  According to the fifth aspect of the present invention, in the antenna device according to the second aspect, the coil is inserted into the two opposite sides of the loop-shaped antenna, so that the terminal can be It is possible to easily balance the communication distance.

  According to a sixth aspect of the present invention, in the antenna device according to the first aspect, when the loop-shaped antenna is arranged close to the metal body, the coil is at the end of the metal body. With such a configuration, a portion having a high eddy current density of the metal body can be used, and thus an antenna device having good communication performance can be provided.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a conceptual diagram of an antenna device according to an embodiment of the present invention.

  The loop-shaped antenna 1 provides a path through which current flows from the antenna input / output terminal 4 (or 5) to the other antenna input / output terminal 5 (or 4). It is defined that a signal is transmitted and received by a current generated by a magnetic field from. Further, a surface surrounded by the line of the loop-shaped antenna 1 is defined as an opening surface of the loop-shaped antenna 1.

  In other words, in this embodiment, the loop antenna 1 is adjusted so that, for example, RFID (13.56 MHz) radio waves can be transmitted and received.

  In this embodiment, two places are inserted together with the core 3 around which the coil portion 2 is wound in the middle of the line constituting the loop-shaped antenna 1. Assuming that the coil axis of one coil part 2 is A, the arrangement of the coil part 2 is such that the coil axis A is parallel to the opening surface of the loop antenna 1 and the coil of the line of the loop antenna 1 is It is perpendicular to the direction of current flowing through the inserted front and rear portions (in this embodiment, the direction of C in FIG. 1).

  In this embodiment, the coil axis A is perpendicular to the C direction, but must be parallel.

  In the present embodiment, the coil portion 2 is disposed so as to be perpendicular to the end surface B of the metal body 6 disposed at a distance D. Although the distance D can be considered from 0 mm to ∞, as will be described later, in any case, the antenna device has good communication performance.

  In addition, the magnetic material used for the core 3 can be increased because the magnetic flux passing through the coil portion 2 can be increased, and the communication performance is improved when a metal body is in close proximity. It may be composed of.

  In FIG. 1, the case where there are two coil portions 2 is shown, but the present invention is not limited to two. Moreover, although the coil part 2 is inserted in two sides which face each other in FIG. 1, this arrangement is preferable because the communication distance on the left and right of the terminal can be balanced, for example.

  Further, in FIG. 1, the two coil portions 2 have the same shape, but the shape, the number of windings, and the like may be different. However, it is preferable to use the coil portion 2 having the same shape because an attachment error at the time of mass production and a reduction of parts types can be achieved.

  In addition, in this embodiment, the number of windings of the conductor of the coil portion 2 is illustrated with about 1.5 turns, and the number of conductors wound on the surface of the core 3 facing the metal body (the surface of the core 3 facing the metal body). The number of conductors wound on the surface when the conductor is wound around the core 3 is less than the number of conductors wound on the surface opposite to the surface facing the metal body of the core 3. Yes.

  By comprising in this way, it can be set as an efficient antenna device with few winding times.

  Here, the results of the winding number experiment are shown in FIG. The horizontal axis plotted the number of windings, and the vertical axis plotted the values normalized by the magnetic field strength at 0.5 windings. The coil part 2 used in the experiment uses 21 mm × 4 mm × 0.2 mm ferrite for the core 3, and a 0.1 mm-thick copper thin plate is changed from 1 mm to 0.6 mm in width according to the number of turns. did. Coil portion 2 is placed close to the end of the metal body, 50Ω is matched at 13.56 MHz, a 20 dBm sine wave signal is input from the signal generator to the antenna at 13.56 MHz, and the main surface of the metal body is The magnetic field strength in the sky 30 mm was measured.

  As shown in FIG. 19, the magnetic field strength increases as the number of turns increases. However, considering the rate of increase, it can be seen that when the number of windings increases from an integer by a half turn, it greatly increases. Although the conductor on the side not facing the metal body 6 is less affected by the eddy current on the surface of the metal body 6, the conductor of the coil portion 2 on the side facing the metal body 6 is affected by the eddy current on the surface of the metal body 6. Since a current in the direction of cancellation is generated, it can be estimated that the increase in magnetic field strength is small when the number of turns is an integral multiple.

  Here, the experiment of FIG. 19 was performed in a state where the loop-shaped antenna 1 was not formed. However, even when the loop-shaped antenna 1 is formed, the influence of the coil portion 2 from the metal body 6 is considered similarly. Therefore, it can be said that the coil unit 2 inserted in the loop-shaped antenna 1 can be an efficient antenna device with a small number of turns.

  However, the number of turns is not limited, and the number of turns may be more or less than about 1.5 turns shown in FIG.

  It should be noted that increasing or decreasing the number of windings by about 0.5 turns from the integral multiple is because both ends of the coil portion 2 (connection portions with the loop-shaped antenna 1) can be formed on both sides with the core 3 interposed therebetween. It becomes easy to insert the antenna 1.

  That is, since it can be inserted in such a way as to replace the straight portion of a normal loop antenna, it becomes easier to insert.

  Moreover, about the winding method of the coil part 2, it may be right-handed or left-handed, and can be suitably selected according to the position to arrange | position.

  Further, the connection between the coil portion 2 and the conductor of the loop-shaped antenna 1 can be performed by a commonly used connection method such as connection by solder or a connector. Alternatively, the coil portion 2 and the loop-shaped antenna 1 may be formed by a single connected conductor. As is generally known, the antenna input / output terminals 4 and 5 are connected to the matching circuit and the input / output terminals of the IC, and the connection method is contact or soldering with a pin or a spring, connection with a connector, or the like. A commonly used connection method can be used.

  FIG. 2 is a conceptual diagram of an antenna device according to an embodiment of the present invention. In the above embodiment, the coil axis of the coil part 2 is parallel to the short side of the core 3, but in FIG. 2, the coil axis of the coil part 2 is parallel to the long side of the core 3. The shape of the coil part 2 and the core 3 is different. That is, as shown in FIG. 2, the shapes of the coil portion 2 and the core 3 can be freely selected according to desired characteristics and mounting space.

  FIG. 3 is a conceptual diagram of an antenna device according to an embodiment of the present invention.

  A loop-shaped antenna 1, a coil portion 2, a core 3, and antenna input / output terminals 4, 5 are arranged in the vicinity of the metal body 6. The coil portion 2 is disposed so as to be positioned at the end portion of the metal body 6. When a magnetic field in a direction perpendicular to the opening surface of the loop antenna 1 comes from the outside, an eddy current is generated on the surface of the metal body 6. Since the density of the eddy current is higher at the end of the metal body 6, the eddy current flowing on the surface of the metal body 6 is most efficiently arranged by placing the coil portion 2 at the end of the metal body 6. It is preferable because it can be used well. Moreover, since the density of the eddy current is low in the quadruple portion of the metal body 6, it is preferable to avoid the arrangement of the coil portion 2 in the quadruple portion.

  FIG. 3 assumes a mobile terminal in which it is difficult to secure a gap between the antenna device and the metal body 6. In this case, the metal body 6 is a substrate in the mobile terminal, for example. A liquid crystal display panel or the like may be used. The conductor constituting the loop-shaped antenna 1 may be composed of a coated copper wire or the like, but may be an electrode pattern or the like formed on the metal body 6. The coil unit 2 and the magnetic core 3 may also be mounted on the metal body 6. Although not shown, other components such as a camera module, a speaker, an RF module, an antenna for other frequencies, and the like can be mounted in a vacant space inside the loop of the loop antenna 1.

  Next, the operation concept of the antenna device of the present invention will be described with reference to FIGS.

  FIG. 4 is a conceptual diagram of the present invention when transmitting from an antenna when the metal body is far away. A current 7 flows through the loop antenna 1 due to a signal input to the antenna input / output terminals 4 and 5, and a magnetic field 8 is generated. Since the magnetic field 13 generated by the coil unit 2 is orthogonal to the magnetic field 8, there is no influence on the magnetic field 8. Although an eddy current 9 is generated in the metal body 6 in a direction that cancels the magnetic field 8 caused by the current 7, it does not have a great influence because it is far away. Therefore, when the metal body 6 is far away, communication is performed in the same manner as a conventional loop antenna, so that the antenna device of the present invention can obtain a good communication state even when the metal body is far away.

  FIG. 5 is a conceptual diagram of the present invention when the metal body is far away and the antenna receives a magnetic field from the outside. The magnetic field 10 from the outside and the magnetic field 11 passing through the loop-shaped antenna 1 have a relationship according to the distance. A current 7 is induced in the loop-shaped antenna 1 by the magnetic field 11, and the antenna input / output terminals 4, 5 are connected. Go out through. Since the coil axis of the coil portion 2 is orthogonal to the magnetic field 11, the current 7 is not affected. An eddy current 9 due to the magnetic field 10 is generated in the metal body 6 and a magnetic field 12 in the opposite direction is formed, but the influence is small because it is far away. Therefore, when the metal body 6 is far away, communication is performed in the same manner as a conventional loop antenna, so that the antenna device of the present invention can obtain a good communication state even when the metal body is far away.

  That is, in this embodiment, the coil portion 2 is arranged so that a current is generated in a direction that cancels the eddy current 9.

  FIG. 6 is a conceptual diagram of the present invention when transmitting from an antenna when a metal body is in the vicinity. A current 7 flows through the loop antenna 1 due to a signal input to the antenna input / output terminals 4 and 5, and a magnetic field 8 is generated. An eddy current 9 is generated in the metal body 6 in a direction that cancels the magnetic field 8 caused by the current 7. As a result, the magnetic field 8 should be reduced and the communication performance of the antenna should be deteriorated. A magnetic field 13 penetrating the coil portion 2 is generated, and an electric current 14 is generated in the metal body 6 by the magnetic field 13. Since the current 14 is opposite to the eddy current 9 and cancels out, the magnetic field 8 is less affected by the eddy current 9 as a result. Therefore, even when the metal body 6 is in the vicinity, the antenna device of the present invention can obtain a good communication state.

  FIG. 7 is a conceptual diagram of the present invention when the metal body is in the vicinity and the antenna receives a magnetic field from the outside. A current 7 is generated in the loop antenna 1 and an eddy current 9 is generated in the metal body 6 by the magnetic field 10 from the outside. Since the metal body 6 and the loop-shaped antenna 1 are close to each other, the magnetic field 11 passing through the loop-shaped antenna 1 is reduced by the magnetic field 12 in the opposite direction due to the eddy current 9, and as a result, the current 7 should be reduced. However, when the magnetic field generated by the eddy current 9 passes through the coil part 2, a current that creates the magnetic field 13 flows through the coil part 2, and as a result, the current 7 does not decrease. Therefore, even when the metal body 6 is in the vicinity, the antenna device of the present invention can obtain a good communication state.

  As a comparative example, FIG. 8 is a conceptual diagram of a conventional example in the case of transmitting from an antenna when a metal body is in the vicinity. When away from the metal body, of course, it is not affected by the metal body. However, as shown in FIG. 8, a current 7 flows to the loop-shaped antenna 101 by a signal input to the antenna input / output terminals 4 and 5. A magnetic field 8 is generated. An eddy current 9 is generated in the metal body 6 in a direction that cancels the magnetic field 8 caused by the current 7. As a result, the magnetic field 8 becomes smaller and the communication performance of the antenna deteriorates. Therefore, when the metal body 6 is in the vicinity, sufficient communication performance cannot be obtained with the conventional loop antenna 101.

  FIG. 9 is a conceptual diagram of a conventional example when the metal body is in the vicinity and the antenna receives a magnetic field from the outside. A current 7 is generated in the loop antenna 101 and an eddy current 9 is generated in the metal body 6 by the magnetic field 10 from the outside. Since the metal body 6 and the loop-shaped antenna 101 are close to each other, the magnetic field 11 passing through the loop-shaped antenna 101 is reduced by the magnetic field 12 in the opposite direction due to the eddy current 9, and as a result, the current 7 is decreased. Therefore, when the metal body 6 is in the vicinity, sufficient communication performance cannot be obtained with the conventional loop antenna 101.

  In the situation shown in FIGS. 8 and 9, it is common to use the magnetic sheet 115 as shown in FIG. 10 in order to reduce the influence of the metal body 6, but the antenna occupation area and thickness increase, and the antenna It becomes difficult to reduce the size of a mobile phone or the like equipped with.

  In the state of FIGS. 6 and 7 as the present embodiment, it can be said that the metal body 6 is used as an antenna by utilizing the current flowing through the metal body 6. Since a metal body in a mobile terminal is often larger than an antenna device, it can be considered that the use of a large metal body as an antenna device with an antenna having a small occupied area can greatly contribute to the future miniaturization and thinning of the mobile terminal.

  In each of the above drawings, the loop-shaped antennas 1 and 101 are drawn in one turn, but the number of turns is not limited to one turn, and may be a plurality of turns. In the case of a plurality of turns, only a part of the outermost line of the loop antenna 1 is configured by the coil part 2 or is inserted into the line of each turn so that the coil axis of each coil part 2 is common. Such an arrangement is preferable because deterioration in communication performance when a metal body is in close proximity is reduced. Further, although shown by one line, it is for simplification of the drawing, and actually has a width and thickness.

  FIG. 14 shows the results of experiments using the antenna apparatus of the present invention and a comparative antenna configured with a conventional structure as shown in FIG. The horizontal axis shows the distance between the metal body and the antenna, and the vertical axis shows the magnetic field strength measured 30 mm above the antenna when the antenna is matched to 50Ω at 13.56 MHz and a 13.56 MHz, 20 dBm sine wave signal is input. Are plotted.

  The antenna device of the present invention used for the experiment has a loop outer shape of 40 mm × 25 mm, two 25 mm sides, a 21 mm × 4 mm × 0.2 mm magnetic core with a line width of 1 mm and a thickness of 0.1 mm. A prototype was produced with the configuration as shown in Example 1 of FIG. 1, in which a copper thin plate was used to replace each coil wound by 1.5 turns. A comparative antenna having a conventional structure was prototyped with the same configuration as shown in FIG. 13, which had the same external dimensions of 40 mm × 25 mm, and was configured with one turn using a copper thin plate having a line width of 1 mm and a thickness of 0.1 mm. A solid substrate having a size assumed to be a 40 mm × 110 mm portable terminal was used as the metal body.

  As can be seen from FIG. 14, the magnetic field strength is less than 1/10 when the conventional one is approaching compared to when it is away from the metal body, whereas the communication characteristics cannot be maintained. In the antenna device of the present invention, the deterioration of the magnetic field strength is small even when the metal body approaches, and the communication characteristics can be maintained even when the metal body is close. Therefore, it can be said that the present invention can provide an antenna device having good communication performance regardless of the distance between the antenna and the metal body.

  Next, the communication range of the present invention will be described with reference to FIGS.

  FIG. 15 shows the result of measuring the magnetic field strength from 0 ° to 90 ° at a distance of 30 mm from the side surface of the antenna by arranging the antenna used in the experiment of FIG. 14 as shown in FIGS. As the substrate 27, a solid substrate of 40 mm × 110 mm size imitating a portable terminal is used. In the measurement of the comparative antenna of the conventional configuration, the magnetic field strength in the 0 ° direction is almost the same as that in FIG. As shown, a 41 mm × 26 mm × 0.2 mm magnetic sheet is inserted between the loop antenna 101 and the substrate 27.

  As can be seen from FIG. 15, the antenna device of the present invention has a magnetic field strength in the 90 ° direction that is stronger than the comparative antenna of the conventional configuration. This is thought to be because the magnetic field in the 90 ° direction was strengthened because the coil axis was parallel to the substrate.

  That is, conventionally, the coil axis of the loop antenna is perpendicular to the substrate, so that the communication characteristics can be maintained in the direction perpendicular to the substrate (that is, the 0 ° direction), but in the case of the 90 ° direction. However, in this embodiment, the coil axis of the coil portion coincides with the direction of the magnetic field in the case of the 90 ° direction, since the coil axis of the loop antenna is perpendicular to the direction of the magnetic field. Therefore, communication characteristics can be maintained.

  As shown in FIG. 18, this is advantageous in communication between terminals (peer-to-peer) in which terminals 28 and 29 are arranged side by side while exchanging data while looking at the screen. The present invention can be said to be very effective because it is compatible with communication in the direction of the back of the terminal such as a ticket gate (0 ° direction in FIG. 15).

  In this embodiment, a loop antenna is used. However, as shown in FIG. 11, the terminal 16 of the coil portion 2 mounted on the metal body 6 is connected to the ground of the metal body 6. You may make it a shape.

  In this case, considering the case where the terminals 16 are connected to each other by the coated copper wire in close contact with the metal body 6, there is no current induced by the copper wire in this portion, so the potentials of the terminals 16 may be equal. Recognize.

  Accordingly, the terminal 16 can be connected to the metal body 6, and the antenna input / output terminal 4 passes through the coil portion 2 and the terminal 16, passes through the metal body 6, and passes through the other terminal 16 and the coil portion 2. A loop path leading to the output terminal 5 is formed. By doing so, a part of the conductor of the loop antenna 1 can be omitted, and the terminal design can be simplified.

  Next, the case where the antenna device of the present invention is mounted on a portable terminal will be described in detail. FIG. 12 is a perspective view when the portable terminal in the embodiment of the present invention is disassembled.

  The portable terminal 20 includes a liquid crystal panel 21, operation buttons 22, a casing 25 and a casing 26, a substrate 23 accommodated therein, a battery 24, and the like. The loop-shaped antenna 1, the coil portion 2, the core 3, and the antenna input / output terminals 4 and 5 according to the present invention are formed inside the housing 26. The loop-shaped antenna 1 line and antenna input / output terminals 4 and 5 are formed by sheet metal, metal foil tape, printing, or the like, and the coil portion 2 is attached to a predetermined place by sticking with an adhesive tape or fixing with a screw. . The connection of the loop-shaped antenna 1 line and the coil portion 2 is performed by contact connection such as a connector or crimping, or soldering or welding, and the connection between the antenna input / output terminals 4 and 5 and the IC is made by pin contact. In addition, connector connection, soldering of conductive wires, etc. are conceivable. Components such as an RF-ID IC, a matching circuit, an antenna for other frequencies, a camera unit, a speaker, and an RF module are arranged in the space formed between the housing 26 and the substrate 23. These components and the loop-shaped antenna 1 are arranged. And good communication can be performed even if the coil part 2 and the core 3 are in contact or separated.

  1 to 3, the end surface of the metal body 6 is formed with a flat surface, and the coil portion 2 is also formed with a straight conductor, but the end surface of the metal body 6 may be a curved surface as shown in FIG. 20. The coil part 2 may also be formed in a curved shape that matches the curved surface of the metal body 6.

  According to the antenna device of the present invention, since the communication characteristics of the antenna can be maintained regardless of the distance between the antenna and the metal body in the casing on which the antenna is mounted, the antenna of various electronic devices such as mobile phones can be maintained. Useful as.

DESCRIPTION OF SYMBOLS 1 Loop-shaped antenna 2 Coil part 3 Core 4, 5 Terminal for antenna input / output 6 Metal body 7, 14 Current 8, 10, 11, 12, 13 Magnetic field 9 Eddy current 16 Terminal 20 Mobile terminal 21 Liquid crystal panel 22 Button 23 Substrate 24 Battery 25, 26 Case 27 Board

Claims (6)

A loop antenna,
A coil inserted in the loop-shaped antenna line,
In the coil, the coil axis of the coil is parallel to the opening surface of the loop-shaped antenna,
And the antenna apparatus characterized by being non-parallel to the direction of the electric current which flows through the part before and after the said coil of the said loop-shaped antenna track | line was inserted. The antenna device according to claim 1, wherein a plurality of the coils are provided in the loop-shaped antenna. 2. The antenna device according to claim 1, wherein the number of windings of the conductor constituting the coil is greater or less than an integral multiple by approximately a half turn. A metal body provided on one surface of the opening surface of the loop-shaped antenna is provided, and the number of the conductors wound around the metal body side surface of the coil is a surface opposite to the metal body side surface. The antenna device according to claim 3, wherein the number is less than the number of the conductors wound around. 3. The antenna device according to claim 2, wherein the coil is inserted into two opposite sides of the loop-shaped antenna. 2. The antenna device according to claim 1, wherein the coil is located at an end of the metal body when the loop-shaped antenna is arranged close to the metal body.

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