WO2011010440A1

WO2011010440A1 - Antenna device

Info

Publication number: WO2011010440A1
Application number: PCT/JP2010/004568
Authority: WO
Inventors: 堀内秀晃; 西山雅史
Original assignee: 三菱電線工業株式会社; 三菱マテリアル株式会社
Priority date: 2009-07-18
Filing date: 2010-07-14
Publication date: 2011-01-27
Also published as: JP2011024146A

Abstract

Disclosed is an antenna device which is compatible with a metallic body and with which miniaturization can be achieved, and which is subject to few restrictions regarding the installation location. An antenna device (1) installed on a metallic body comprises: a main antenna body (4) constituted by winding wire around a magnetic core formed of a magnetic material; a sealing body (5) accommodating the main antenna body; and a non-magnetic conductive sheet (6) that covers the surface of the sealing body (5) opposite the metallic body. In this way, by providing a space (sealing body (5)) between the non-magnetic conductive sheet (6) and the main antenna body (4), compared to when there is no such space (i.e. when the non-magnetic conductive sheet (6) is directly affixed to the main antenna body (4)), the main antenna body (4) is further away from the metallic body, so the Q value increases and the rate of frequency variation decreases, and, in addition, an "On Metal" (registered trademark) effect can be obtained.

Description

Antenna device

The present invention relates to an antenna device suitable for a keyless entry system or the like of a car.

In recent years, an electronic key system called a so-called smart keyless entry system or passive keyless entry (PKE) for locking / unlocking a vehicle door such as a car without key operation is becoming standard. In this PKE, door lock / unlock control can be performed by the operation of a sensor or switch of a vehicle using wireless communication without the operation of an electronic key (FOB) possessed by the owner of the vehicle.

In these electronic key systems, for example, a ferrite bar antenna in which a wire is wound around a ferrite bar is adopted as a small space-saving antenna for communication, but when attached to a metal body such as a center pillar of a car, a metal body Under the influence of Q, the communication distance becomes short, so it was installed away from the metal body. Thus, there is a disadvantage that the installation place of the antenna is restricted.

Therefore, conventionally, for example, in Patent Document 1, a magnetic path member in which an antenna for transmitting and receiving electromagnetic waves is configured by attaching an antenna coil to a magnetic core made of a magnetic body, an attachment portion of the magnetic path member and a magnetic path member A keyless entry system has been proposed that includes a nonmagnetic conductive sheet interposed therebetween.

In this keyless entry system, by arranging the ferrite bar antenna on the nonmagnetic metal, it is possible to concentrate the magnetic flux on the magnetic core, which corresponds to installation on a metal body such as a car door. In this ferrite bar antenna, a nonmagnetic conductive sheet is directly attached to the ferrite bar antenna adjusted to an arbitrary resonance frequency including a capacitor for resonance, thereby reducing the influence of the metal body and reducing the resonance frequency. We have suppressed the deviation and the drop in Q value.

This ferrite bar antenna has a Q value higher than when directly attached to a vehicle body by interposing a nonmagnetic metal, so that the influence of the vehicle body on the antenna can be suppressed by so-called on metal (registered trademark). This On Metal (registered trademark) reduces the influence of the metal body by interposing a nonmagnetic conductive sheet between the antenna body (the antenna body formed by winding a wire around the ferrite bar) and the metal body. Point to a technology (effect) or its structure capable of suppressing the shift of the resonance frequency and the decrease of the Q value.

JP 2008-252462 A (claims, FIG. 3)

However, the following problems still remain in the above-described conventional technology. That is, in the antenna corresponding to the conventional metal body, in order to attach a copper plate etc. as a nonmagnetic metal plate to the ferrite bar antenna, the Q factor is increased and the frequency change is reduced. There is a disadvantage that the nonmagnetic conductive sheet has to be set sufficiently large.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an antenna device capable of coping with a metal body, increasing the Q value, reducing the frequency change, and reducing the restriction on the installation location.

The present invention adopts the following configuration in order to solve the problems. That is, the antenna device of the present invention is an antenna device installed on a metal body, and the antenna body on which a wire is wound, a housing body for housing the antenna body, and the metal body of the housing body And a nonmagnetic conductive sheet covering the opposite surface.

In this antenna device, since the nonmagnetic conductive sheet covers the surface of the storage body facing the metal body, by providing a space (storage body) between the nonmagnetic conductive sheet and the antenna main body, In addition to the fact that the antenna body is further from the metal body and the Q value becomes larger and the frequency change rate becomes smaller than when the space is not provided (when the nonmagnetic conductive sheet is directly attached to the antenna body) It is possible to obtain the effect of making it a trademark.

Further, in the antenna device of the present invention, the nonmagnetic conductive sheet covers not only the surface of the storage body facing the metal body but also a part of the outer periphery of the storage body adjacent to the surface. It features. That is, in this antenna device, the nonmagnetic conductive sheet covers not only the surface of the storage body facing the metal body but also a part of the outer periphery of the storage body adjacent to the surface. In this case, a nonmagnetic conductive sheet such as a copper foil or a copper plate is attached not only to the installation surface facing the metal body but also to the side surface of the storage body to be bent as a whole. Similar effects of on-metalization can be obtained. That is, by adopting the on-metal (registered trademark) structure by the nonmagnetic conductive sheet disposed up to a part of the outer periphery of the storage body, the influence of the metal body (resonance frequency shift, reduction of Q value, etc.) It becomes possible to suppress. Therefore, even on metal, the Q value is high, the frequency change is small, and miniaturization is possible. If the mounting area is approximately the same as the mounting surface of the storage body, mounting is possible, and there are few restrictions on the mounting location. Moreover, the change of the frequency and Q value by the change of input electric power can also be suppressed by this nonmagnetic electroconductive sheet.

Further, in the antenna device of the present invention, the nonmagnetic conductive sheet is composed of a plurality of members separated from each other. That is, in this antenna device, since the nonmagnetic conductive sheet is composed of a plurality of separate bodies, it is necessary to attach different shapes corresponding to the surface shape and the mounting location of the storage body, etc. As a result, the mounting operation and the like are facilitated, and materials of different characteristics can be attached correspondingly to the surface, and the characteristics can be further improved.

Further, the antenna device of the present invention is characterized in that the antenna main body includes a magnetic core formed of a magnetic material on which the wire is wound. That is, in this antenna device, the antenna main body includes the magnetic core formed of the magnetic material on which the wire is wound, so that the characteristics can be further improved.

Further, the antenna device of the present invention is characterized in that the nonmagnetic conductive sheet covers the outer periphery of the storage body to the same height as the lower end of the antenna main body in the storage body. That is, in this antenna device, since the nonmagnetic conductive sheet covers the outer periphery of the storage body to the same height as the lower end of the antenna main body in the storage body, the magnetic flux emitted laterally and upward from the antenna main body is stored Interference with the nonmagnetic conductive sheet on the outer periphery of the body can be suppressed, and good communication characteristics can be obtained.

Further, the antenna device of the present invention is characterized in that the antenna main body is stored close to the side opposite to the surface of the storage body facing the metal body. That is, in this antenna device, since the antenna main body is stored close to the side opposite to the surface of the housing facing the metal body, the antenna main body is moved away from the metal body to be attached. Can be reduced as much as possible.

Further, the antenna device of the present invention is characterized by including an electronic component for resonance frequency adjustment which is housed in the housing and connected to the wire. That is, in this antenna device, since the electronic component for resonance frequency adjustment stored in the storage body and connected to the wire is provided, the antenna main body and the electronic component are integrally stored in the storage body, and the number of mounting steps and the mounting space Can be reduced.

According to the present invention, the following effects are achieved. According to the antenna device of the present invention, since the nonmagnetic conductive sheet covers the surface of the housing facing the metal body, the Q value is high even on metal, and the change in frequency is small and the on metal (registered trademark) is formed. You can get the effect. Therefore, it can be applied to a metal body such as a center pillar of an automobile, has less restriction on the installation position, and is suitable as an antenna device used for a keyless entry system or the like.

It is a perspective view showing a 1st embodiment of an antenna device concerning the present invention. In 1st Embodiment, it is a top view which shows an antenna apparatus. FIG. 3 is a cross-sectional view taken along line AA of FIG. It is a sectional view showing a 2nd embodiment of an antenna device concerning the present invention. It is a sectional view showing a 3rd embodiment of an antenna device concerning the present invention. It is sectional drawing which shows 4th Embodiment of the antenna apparatus which concerns on this invention. In the Example of the antenna apparatus which concerns on this invention, it is a graph which shows the relationship of the width and Q value from the center to the side end of the nonmagnetic electroconductive sheet at the time of installing on a metal body. In the Example of the antenna device which concerns on this invention, it is a graph which shows the relationship of the width | variety from the center to the side end of a nonmagnetic conductive sheet at the time of installing on a metal body, and a frequency change. It is a graph which shows the frequency change rate to input electric power in the case of the conventional example installed on free space and a metal body, and the antenna apparatus of a present Example. It is a graph which shows Q value change rate to input electric power in the case of the conventional example installed on free space and a metal body, and the antenna apparatus of a present Example. It is sectional drawing which shows the other example in 1st Embodiment of the antenna apparatus which concerns on this invention.

Hereinafter, a first embodiment of an antenna device according to the present invention will be described with reference to FIGS. 1 to 3.

The antenna device in the present embodiment is, for example, an LF (Low Frequency) band antenna used for a passive keyless entry system mounted on a vehicle such as an automobile, and directly or close to a metal body near the door as an outdoor antenna. It will be installed in the state.

The antenna device 1 includes an antenna main body 4 which is a ferrite bar antenna in which a wire 3 is wound around a ferrite bar (magnetic core) 2 made of a magnetic material as shown in FIGS. 1 to 3 and the antenna main body A sealed body (housing body) 5 for sealing and storing 4, a nonmagnetic conductive sheet 6 provided on the installation surface of the sealed body 5, and the sealed body 5 for sealing And a resonance capacitor (an electronic component for adjusting a resonance frequency) 8 connected to the wire 3 through a wire 7.

The LF band in the present embodiment is 30 kHz to 300 kHz, and specifically, 125 kHz band and 134 kHz to 135 kHz band. The ferrite bar 2 is formed of, for example, a Ni--Zn magnetic material. Moreover, the insulated wire which coat | covered the polyurethane resin on the outer periphery of the copper wire, for example is employ | adopted for the said wire 3, and it connects to the wiring 7. FIG.

The sealing body 5 is a rectangular parallelepiped shape extending in the extending direction of the antenna main body 4 and is made of a material such as resin or rubber and seals the antenna main body 4 by a known method (injection molding or the like). In addition, as a thing other than the above-mentioned mode of closure object 5, there is a thing formed by combination (combination of antenna main part 4 and a case made of resin or rubber (the antenna main part 4 is stored in a case)). The antenna main body 4 is preferably sealed and housed in the sealing body 5 at a position close to the side opposite to the surface (installation surface) of the sealing body 5 facing the metal body.

The nonmagnetic conductive sheet 6 is a part of the side from the installation surface of the sealing body 5, that is, the sealing body 5 adjacent to the surface in addition to the surface (installation surface) of the sealing body 5 facing the metal body. It also covers a part (side) of the outer circumference of the. More specifically, as shown in FIG. 3, the nonmagnetic conductive sheet 6 covers the side surface of the sealing body 5 to the same height as the lower end of the antenna main body 4 in the sealing body 5. The nonmagnetic conductive sheet 6 is, for example, a copper foil with an adhesive layer, and is attached to the installation surface and the side surface of the sealing body 5 in a U-shape.

As the nonmagnetic conductive sheet 6, metal plates such as aluminum, aluminum alloy, copper alloy, stainless steel, magnesium alloy, bronze, brass, etc. can be adopted in addition to copper foil, and among them, it is possible to conduct electricity. Gold, silver, copper, aluminum or their alloys are preferred in terms of large rates, and copper, aluminum, copper alloys, aluminum alloys are optimal in terms of cost.

In addition, although the thickness of the nonmagnetic conductive sheet 6 is generally preferably large, the effect (the effect of reducing the rate of change in frequency) is not significantly improved if the thickness is too large. In the case of sticking to the stopper 5, it is sufficient if it is 0.1 mm or less, preferably, the frequency change rate is suppressed, and an adhesive or the like is applied to one surface of the nonmagnetic conductive sheet 6 Copper having a preferred thickness of 0.02 mm to 0.08 mm and good conductivity, in that it can be attached along the shape of (5) (the shape of the portion / surface to be bonded to the sealing body 5); It is more preferable if it is aluminum.

The nonmagnetic conductive sheet 6 may have a thickness greater than 0.1 mm, and the shape of the sealing body 5 by punching, pressing, etc. (the shape of the place or surface attached to the sealing body 5) , And may be affixed to the sealing body 5 via an adhesive or fixed to the sealing body 5 with a bolt or the like. It is also possible to use a nonmagnetic conductive sheet (plate) such as punching or pressing as it is as an attachment to an article.

In addition, the installation surface of the sealing body 5 is a surface facing the metal body when installed on the metal body, and may be attached to a predetermined location by adhesion or the like on the surface opposite to the installation surface. Absent. That is, the antenna device 1 may not only be fixed to the metal body, but may be fixed to another member or the like in a state of being in proximity to the metal body. For example, a multilayer ceramic chip capacitor is employed as the resonance capacitor 8.

As described above, in the antenna device 1 of the present embodiment, the nonmagnetic conductive sheet 6 covers the surface (placement surface) of the sealing body 5 facing the metal body, and thus the nonmagnetic conductive sheet 6 and the antenna Since the space (the sealing body 5) is provided between the main body 4 and the case where the space is not provided (the case where the nonmagnetic conductive sheet 6 is directly attached to the antenna main body 4), the antenna main body 4 In addition to the longer distance and the higher the Q value and the lower the frequency change rate, the effect of on metal (registered trademark) can be obtained.

Further, since the nonmagnetic conductive sheet 6 covers not only the surface (placement surface) facing the metal body of the sealing body 5 but also a part (side surface) of the outer periphery of the sealing body adjacent to the surface, copper foil A nonmagnetic conductive sheet 6 such as a copper plate or the like is bent to the side of the sealing body 5, and the same on-metal (registered trademark) effect as a large flat copper plate can be obtained.

That is, by adopting the on-metal (registered trademark) structure of the nonmagnetic conductive sheet 6 disposed on the side surface, it is possible to further suppress the influence of the metal body (resonance frequency shift, Q value decrease, etc.). Therefore, even on metal, the Q value is high, the frequency change is small, and miniaturization is possible. If the mounting area is approximately the same as the mounting surface of the sealing body 5, mounting is possible, and there are few restrictions on the mounting location. Further, the nonmagnetic conductive sheet 6 can also suppress changes in frequency and Q value due to changes in input power.

In addition, since the nonmagnetic conductive sheet 6 covers the side surface of the sealing body 5 to the same height as the lower end of the antenna main body 4 in the sealing body 5, the nonmagnetic conductive sheet 6 is emitted sideward and upward from the antenna main body 4 It is possible to suppress the magnetic flux from being disturbed by the nonmagnetic conductive sheet 6 on the side, and good communication characteristics can be obtained.

Furthermore, by storing the antenna main body 4 close to the side opposite to the mounting surface of the sealing body 5, the influence of the metal body can be reduced as much as possible by separating the antenna main body 4 from the metal body to be attached. it can. In addition, since the resonance capacitor 8 housed in the sealing body 5 and connected to the wire 3 is provided, the antenna main body 4 and the resonance capacitor 8 are integrally housed in the sealing body 5, and the number of mounting steps and mounting Space can be reduced.

Next, second to fourth embodiments of the antenna device according to the present invention will be described below with reference to FIGS. 4 to 6. In the following description of each embodiment, the same components as those described in the above embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

The difference between the second embodiment and the first embodiment is that in the first embodiment, the sealing body 5 having a rectangular cross section is adopted, and the nonmagnetic conductor sheet 6 is attached to a part of the installation surface and the side surface On the other hand, in the antenna device 21 of the second embodiment, as shown in FIG. 4, the sealing body 25 having a hexagonal cross section is adopted, and not only the installation surface 25a facing the metal body but also the installation surface The nonmagnetic conductor sheet 26 is attached to the whole of the lower surface 25b of the outer periphery adjacent to 25a and a part of the upper surface 25c adjacent to the lower surface 25b.

Further, the third embodiment is different from the first embodiment in that in the first embodiment, the sealing body 5 having a rectangular cross section is employed, whereas in the antenna device 31 of the third embodiment, As shown in FIG. 5, a sealing body 35 having a circular cross section is employed, and not only the lower surface 35a opposed to the metal body but also a part of the upper surface 35b adjacent to the surface 35a is nonmagnetic conductive The point is that the body sheet 36 is attached.

As in the

antenna devices

21 and 31 of the second embodiment and the third embodiment, even when the shapes of the sealing

bodies

25 and 35 are changed according to the attachment location and the like, the

nonmagnetic conductor sheets

26 and 36 are used. By covering not only the surface facing the metal body but also a part of the outer periphery of the sealing

body

25 and 35 adjacent to the surface, the Q value similar to that of a large flat copper plate or the like as in the first embodiment. It is possible to obtain the suppression effect of the reduction and the frequency change.

The difference between the fourth embodiment and the first embodiment is that in the first embodiment, one nonmagnetic conductor sheet 6 is bent and attached to part of the installation surface and the side surface of the sealing body 5 On the other hand, in the antenna device 41 of the fourth embodiment, as shown in FIG. 6, the first nonmagnetic conductor sheet 46a attached to the installation surface of the sealing body 5 and the second nonmagnetic conductor attached to the side surface. The magnetic conductive sheet 46b is different from the nonmagnetic conductive sheet 46b.

That is, in the antenna device 41 of the fourth embodiment, the first nonmagnetic conductor sheet 46a is formed to conform to the shape of the installation surface of the sealing body 5, and the second nonmagnetic conductor sheet 46b is sealed. It is formed according to the pasting part shape of the side of body 5. The first nonmagnetic conductor sheet 46a and the second nonmagnetic conductor sheet 46b may be formed of the same material, but may be formed of different materials. For example, the first nonmagnetic conductive sheet 46a is formed of copper, the second nonmagnetic conductive sheet 46b is formed of a copper alloy, and the first nonmagnetic conductive sheet 46a is formed of aluminum, and The nonmagnetic conductor sheet 46b may be made of copper.

Thus, in the fourth embodiment, since the nonmagnetic conductive sheet is composed of a plurality of first nonmagnetic conductive sheet 46a and second nonmagnetic conductive sheet 46b which are separate from each other, Different shapes can be attached to correspond to the surface shape and attachment location of the sealing body 5, etc., and the attachment work and the like can be facilitated, and materials of different characteristics can be attached corresponding to the surface. It becomes possible to further improve the characteristics.

Next, an antenna device according to the present invention will be specifically described with reference to FIGS. 7 to 10 according to an embodiment.

In the antenna device 1 according to the first embodiment, the width W1 from the center to the side end of the nonmagnetic conductive sheet 6 is changed to produce an example, and the respective Q values when installed on a metal body are measured. The results are shown in FIG. In addition, the installation surface width W0 of the sealing body 5 was set to 14 mm (7 mm from the center to the side end), and the side height T of the sealing body 5 was set to 8 mm. Moreover, the lower end height of the antenna main body 4 in the sealing body 5 is set to 2 mm from the installation surface.

From this result, the Q value increases even if the width W1 from the center to the side end of the nonmagnetic conductive sheet 6 exceeds 7 mm (corresponding to the position on the installation surface side end of the sealing body 5) Recognize. In addition, the Q value is 9 mm in width W1 from the center to the side end of the nonmagnetic conductive sheet 6 (the position of the side height of the sealing body 5 is 2 mm, which corresponds to the height of the lower end of the antenna main body 4) Shows the maximum value. That is, the highest Q value is obtained when the nonmagnetic conductive sheet 6 covers the side surface of the sealing body 5 up to the reverse of the height of the lower end of the antenna main body 4.

Next, in the above embodiment in which the width W1 from the center to the side edge of the nonmagnetic conductive sheet 6 is changed, the results of measurement of changes in the respective resonant frequencies when installed on a metal body are shown in FIG. Show. From this result, it is understood that the frequency change becomes smaller as the width W1 from the center to the side end of the nonmagnetic conductive sheet 6 is larger. That is, the width W1 from the center to the side end of the nonmagnetic conductive sheet 6 exceeds 7 mm (corresponding to the position of the installation surface side end of the sealing body 5), and the side surface of the sealing body 5 is covered more The frequency change is smaller. As described above, by covering not only the installation surface but also the side surface of the sealing body 5 with the nonmagnetic conductive sheet 6, it is possible to improve the Q value and reduce the frequency change.

Next, the results of measurement of the frequency change rate and the Q value change rate with respect to the input power are shown in FIG. 9 and FIG. Generally, in the case of an LF antenna, the frequency and the Q value change depending on the input power (current flowing in the wound wire (winding)), but from the results of the above measurements, it has been found that In the antenna device, as shown in FIG. 9, it is understood that the frequency change rate is almost the same as in the antenna device 1 of the present embodiment, while the frequency change rate is almost the same.

In addition, with regard to the rate of change of the Q value, as shown in FIG. 10, the antenna device 1 of this embodiment is smaller than the conventional antenna devices installed on free space and on a metal body. Recognize. As described above, in the antenna device 1 of the present embodiment, it is possible to suppress changes in the frequency and the Q value according to changes in the input power.

In addition, this invention is not limited to said each embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.

For example, in the first embodiment, as described above, the outer periphery of the sealing body 5 adjacent to the nonmagnetic conductive sheet 6 in addition to the surface (placement surface) facing the metal body of the sealing body 5 It is preferable to cover a part (side surface) of the nonmagnetic conductive sheet 6 as another example, as shown in FIG. It may be attached so as to cover only the installation surface). Even in the case of the antenna device 51 in this case, a space is not provided by providing a space (the sealing body 5) between the nonmagnetic conductive sheet 56 and the antenna main body 4 (nonmagnetic conductive sheet in the antenna main body 4 In addition to the fact that the antenna main body 4 moves away from the metal body and the Q value becomes larger and the frequency change rate becomes smaller, the effect of on metal (registered trademark) can be obtained.

Moreover, in each said embodiment, although the antenna apparatus of this invention was employ | adopted as an antenna for signal transmission / reception of a keyless entry system, you may apply as an antenna of another use. In particular, the antenna device is suitable for installation on a metal body or in proximity to the metal body. For example, RFIDs for metal bodies that can be installed in various metal pipes or metal bodies such as gas pipes, water supplies, sewers, cable pipes, optical fiber pipes, oil transport pipes, chemical liquid transport pipes, etc. and wirelessly communicate identification information It can also be adopted as an antenna device for Radio Frequency Identification) elements.

In each of the above embodiments, although the antenna body and the electronic component are connected by wiring and sealed together in the sealing body, the antenna body itself is an electronic component for adjusting the resonance frequency connected to the wire. It does not matter if it has. For example, a capacitor or an inductor may be provided on a ferrite bar as an electronic component for adjusting a resonance frequency connected to a wire, and the integrated component may be resin-sealed.

Furthermore, the antenna main body and the electronic component for adjusting the resonance frequency may be connected via the lead frame, and in this state, they may be molded and integrated with a sealing body. In addition, although it is preferable to mold-mold by a sealing body and to protect an antenna main body, you may accommodate an antenna main body and an electronic component in housings (storage bodies), such as a storage case. In this case, the same Q as in the above embodiment can be obtained by providing the nonmagnetic conductive sheet so as to cover the nonmagnetic conductive sheet from the installation surface to the side surface of the housing.
The effect of suppressing the value reduction and the frequency change can be obtained.

Moreover, although the antenna main body of said each embodiment winds a wire directly on a ferrite bar, it may wind a wire on a bobbin-like thing and insert a ferrite bar in the center. In addition, although the LF band is adopted as the frequency as described above, the HF band is also effective.

Furthermore, a magnetic sheet may be interposed between the antenna main body and the nonmagnetic conductive sheet. As the magnetic sheet, for example, a sheet formed by dispersing soft magnetic powder such as an amorphous alloy or soft magnetic flake in plastic or rubber can be adopted. Thus, by interposing the magnetic sheet between the antenna main body and the nonmagnetic conductive sheet, the magnetic sheet is electromagnetically shielded, and the magnetic flux passes through the inside of the magnetic sheet without magnetic loss, thereby approaching the metal body. Even if the characteristics are more stable.

As described above, in order to improve the characteristics, it is preferable to adopt the antenna main body in which the wire is wound around the ferrite bar which is the magnetic core, but the magnetic core is not inserted and the coiled (helical) state You may employ | adopt the antenna main body made into resin or the inside of a wire rod.

1, 21, 31, 41, 51 ... antenna device, 2 ... ferrite bar (magnetic core), 3 ... wire rod, 4 ... antenna body, 5, 25, 35 ... sealed body (housing body), 6, 26, 36, 46, 56 ... nonmagnetic conductive sheet, 7 ... wiring, 8 ... capacitor for resonance (electronic component for adjusting resonance frequency) 46a ... first nonmagnetic conductive sheet, 46b ... second nonmagnetic conductive Sheet

Claims

An antenna device installed on a metal body, comprising: an antenna main body on which a wire is wound; a storage body for storing the antenna main body; and a nonmagnetic conductive body covering a surface of the storage body facing the metal body. An antenna device comprising: a sexing sheet.
The antenna device according to claim 1, wherein the nonmagnetic conductive sheet covers not only the surface of the storage body facing the metal body but also a part of the outer periphery of the storage body adjacent to the surface. An antenna device characterized by
The antenna device according to claim 1, wherein the nonmagnetic conductive sheet is composed of a plurality of members separated from one another.
The antenna device according to any one of claims 1 to 3, wherein the antenna main body includes a magnetic core formed of a magnetic material around which the wire is wound.
The antenna device according to any one of claims 1 to 4, wherein the nonmagnetic conductive sheet covers the outer periphery of the storage body to the same height as the lower end of the antenna main body in the storage body. An antenna device characterized by
The antenna device according to any one of claims 1 to 5, wherein the antenna main body is stored close to the side opposite to the surface of the storage body facing the metal body. apparatus.
The antenna device according to any one of claims 1 to 6, further comprising: an electronic component for adjusting a resonance frequency which is housed in the housing and connected to the wire.