JP2003092509A - Antenna coil - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reduce the occupied area by downsizing and to prevent a decrease in receiving sensitivity due to a difference in the installation position of an antenna coil. SOLUTION: A first coil 5 and a second coil 6 are wound around a winding frame portion 3 of a ferrite core 2 so that respective winding axes are orthogonal to each other, and the first coil 5 and the second coil 6 are wound. The third coil 12 was wound around the outer periphery of the first coil 5 and the second coil 6 so as to have a winding axis orthogonal to the winding axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small antenna coil used in, for example, a keyless entry system for wirelessly opening and closing a door of a car and a receiver of a security device.

[0002]

2. Description of the Related Art Conventionally, an antenna coil used in a receiver of a keyless entry system or a security device of this type is often a bar antenna coil in which a rod-shaped ferrite core is wound along the long axis. It was

That is, the bar antenna coil having the above-described structure has the maximum receiving sensitivity to radio waves incident from the direction parallel to the long axis of the ferrite core, and is perpendicular to the long axis of the ferrite core. It has a directivity that minimizes the receiving sensitivity with respect to the incident radio wave, and the receiving sensitivity is extremely lowered depending on the installation direction of the bar antenna coil. For this reason, the bar antenna coil is rarely used alone, and normally, a plurality of bar antenna coils are arranged along the X axis and the Y axis of the circuit board of the receiving device to thereby obtain the receiving sensitivity of the entire antenna coil. Is trying to improve.

[0004]

However, when a plurality of bar antenna coils are arranged along the X-axis and the Y-axis of the circuit board of the receiving device, the area occupied by the antenna coil portion on the circuit board becomes large. Therefore, the size of the device itself in which the antenna coil is installed must be increased, which is against the miniaturization of the device. In addition, the individual bar antenna coils may interfere with each other and the desired reception sensitivity may not be obtained.

The present invention has been made in order to solve the problems of the conventional antenna coil as described above, and an object thereof is to provide an antenna coil which can be reduced in size and weight. Another object of the present invention is to provide an antenna coil capable of obtaining good reception sensitivity with less interference.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, according to the present invention, firstly, a winding frame portion of a core is provided with a first coil and a second coil such that their winding axes are orthogonal to each other. An antenna coil characterized by being wound. A second aspect of the present invention is that a third coil that surrounds the first coil and the second coil and that is wound so that a winding axis is orthogonal to the two coils is arranged. It has a feature. A third aspect of the present invention is characterized in that, in the second aspect, the third coil is wound around a winding frame having an insulating property. According to a fourth aspect of the present invention, the number of windings of each coil in the first to third aspects is adjusted so that the electric field strength or the magnetic field strength induced in each coil is substantially equal. Is characterized by. Furthermore, an antenna coil according to a fifth aspect of the present invention is a flat columnar base, a first coil wound so that the X-axis direction of the base is an axis, and a Y-axis of the base. A second coil wound so that the direction thereof is the axis, and a third coil wound so that the Z-axis direction of the base is the axis, and the first, second, and Each winding path for winding the coil of No. 3 is characterized in that at least a part thereof is a groove. In the antenna coil according to the sixth aspect of the present invention, the base portion has a flat and substantially rectangular parallelepiped shape,
An ear-shaped member is provided at an octagonal base of the rectangular parallelepiped, and a first side portion of the ear-shaped member is arranged so as to be a side wall of a first groove portion around which the first coil is wound. The second side portion of the ring-shaped member is arranged so as to be the side wall of the second groove around which the second coil is wound, and the portion sandwiched by the flat surfaces of the ear-shaped member is the third side. It is characterized in that the coil is arranged so as to be a side wall of the third groove around which the coil is wound. The antenna coil according to the seventh aspect of the present invention is characterized in that the planar shape of the ear-shaped member is formed into a fan shape of a quarter circle. In the antenna coil according to the eighth aspect of the present invention,
One of the end portions of each coil is connected to a common terminal, the remaining three end portions are connected to different terminals, and four terminals are provided. In an antenna coil according to a ninth aspect of the present invention, a winding end side end portion of the first coil, a winding start side end portion of the second coil, and a winding start side end portion of the third coil are provided. , And is connected to the common terminal.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to examples. 1 is a perspective view showing a first embodiment of an antenna coil of the present invention, FIG. 2 is a plan view of the antenna coil, FIG. 3 is a perspective view showing an example of the shape of a ferrite core used for the antenna coil, FIG. Is a perspective view showing a second embodiment of the antenna coil of the present invention, FIG. 5 is a plan view of FIG. 4, FIG. 6 is a perspective view showing the shape of the ferrite core used in FIGS. 4 and 5, and FIG. FIG. 8 is a perspective view showing a third embodiment of the antenna coil of the present invention, and FIG. 8 is an exploded perspective view of the embodiment of FIG. In each figure, the same components are designated by the same reference numerals, and duplicated description will be omitted. Further, the X axis, the Y axis, and the Z axis in the following description are axes of the orthogonal coordinate system.

In FIGS. 1 to 3, reference numeral 1 denotes a small antenna coil, which is formed as a rectangular plate-shaped winding portion 3 and protruding from four corners of the winding portion 3, and is provided with a winding stopper and an electrode. The ferrite core 2 integrally formed with the protrusions 4a, 4b, 4c, and 4d that also serve as the parts, and the two opposing sides of the winding part 3 so that the winding axis is parallel to the X axis of the ferrite core 2. It is composed of a wound first coil 5 and a second coil 6 wound around the other two sides of the winding portion 3 so that the winding axis is parallel to the Y axis of the ferrite core 2. There is. In other words, the winding axis of the first coil 5 and the winding axis of the second coil 6 are orthogonal to each other on the horizontal plane. Also,
Each winding start end and each winding end end of the first coil 5 and the second coil 6 are electrodes formed by a metal terminal plate or solder attached to the protrusions 4a, 4b, 4c, 4d of the ferrite core 2, respectively. The circuit board (not shown) of the electronic device is connected via the section 7.

The second embodiment shown in FIGS. 4 and 5 shows an example in which the shape of the ferrite core 2 is formed in a cross shape, and a portion 3-1 extending in the X-axis direction of the winding portion 3 is formed. The first coil 5 is wound, and its winding start end and winding end end are connected to the electrode portions 7 formed on the protrusions 4e and 4g, respectively. The second coil 6 is wound around the portion 3-2 of the winding portion 3 extending in the Y-axis direction, and the winding start end and the winding end end thereof are electrodes formed on the protrusions 4f and 4h, respectively. It is connected to the section 7.

FIGS. 7 and 8 show a third embodiment different from the above two embodiments. Reference numeral 8 is a winding frame made of an insulating resin or the like, in which a hole or a recess 9 is formed in the central portion. Yes,
Collar part 11a that juts out parallel to the upper and lower four circumferences of the wall part 10.
And 11b are formed. A third winding wire 12 is wound around the outer periphery of the wall portion 10 of the winding frame 8 so that the winding axis is parallel to the Z axis.
Of the coil. Then, in the hole or the recess 9 of the winding frame 8, the first antenna coil portion 13 similar to that of the embodiment shown in FIG. 1 is horizontally arranged. That is, the first antenna coil portion 13 has a ferrite core 2 integrally formed with a rectangular plate-shaped winding portion and projecting portions 4a, 4b, 4c, and 4d that serve as winding stoppers, and the winding axis is the X-axis. First winding on the two opposite sides of the winding part of the ferrite core 2 so as to be parallel to
2 and a second coil 6 wound around the other two sides of the winding portion so that the winding axis is parallel to the Y axis. In addition, the first antenna coil unit 13 of the first
The winding start end and the winding end end of the coil 5 and the second coil 6 and the winding start end and the winding end end of the third coil 12 forming the second antenna coil are respectively wound on the winding frame 8
Are connected to the electrodes 7 disposed on the opposite sides of the collar portions 11a and 11b. Therefore, the third coil 12 forming the second antenna coil portion is arranged so as to surround the first antenna coil portion 13 via the wall portion 10 of the winding frame 8,
In addition, the winding axis is arranged so as to be orthogonal to the first coil 5 and the second coil 6.

In the first embodiment shown in FIGS. 1 and 2 and the second embodiment shown in FIGS. 4 and 5, the electric field intensity induced in each of the first coil 5 and the second coil 6 is The number of windings of each coil is adjusted so that they are substantially equal, and the first coil 5 and the second coil 6 form independent tuning circuit paths, and each tuning circuit is connected to the high frequency amplifier circuit. When the high-frequency amplifier circuit selectively amplifies the stronger one of the output signals of the tuning circuits, the electric field strength induced in the first coil 5 with respect to the radio wave incident from the X-axis direction of the antenna coil 1. Alternatively, since the magnetic field strength increases, the tuning signal of the tuning circuit on the first coil 5 side is amplified by the high frequency amplifier circuit. Further, since the electric field strength or the magnetic field strength induced in the coil 6 becomes strong with respect to the radio wave incident from the Y-axis direction of the antenna coil 1, the tuning signal of the tuning circuit on the second coil 6 side is generated by the high frequency amplifier circuit. It will be amplified. As described above, in the two embodiments shown in FIGS. 1, 2 and 4 and 5, the X-axis and the Y-axis of the antenna coil 1 are used.
It is possible to improve the reception sensitivity with respect to radio waves in a direction horizontal to the surface formed by the axis.

Further, in the third embodiment shown in FIGS. 7 and 8, similarly to the above, the first coil 5, the second coil 6 and the second antenna coil forming the first antenna coil portion 13 are formed. The number of windings of each coil is adjusted so that the electric field strength or the magnetic field strength induced in each of the third coils 12 forming the part becomes substantially equal, and the first coil 5 and the second coil When the coil 6 and the third coil 12 each form an independent tuning circuit, each tuning circuit is connected to a high frequency amplifier circuit, and the high frequency amplifier circuit selectively amplifies the stronger one of the output signals of each tuning circuit. The high-frequency amplifier circuit selectively amplifies the output signal of the tuning circuit formed by the first coil 5 for radio waves incident from the X-axis direction, and first amplifies the output signal of the tuning circuit formed by the first coil 5. Tuning formed by two coils 6 Selectively amplifies the output signal of the road, also for waves incident from Ζ axial selectively amplifies the output signal of the tuning circuit in which the third coil 12 is formed. Thus, in the present embodiment, the antenna coil 1 has good reception sensitivity not only in the direction horizontal to the plane formed by the X axis and the Y axis but also in the radio waves incident from the Z axis direction orthogonal to the horizontal plane. To

9 to 11 show an antenna coil according to the fourth embodiment. In this antenna coil,
The first coil 5 is attached to the base 20 having a flat columnar shape,
The second coil 6 and the third coil 12 are wound. The first coil 5 is wound so that the X-axis direction of the base is the axis, the second coil 6 is wound so that the Y-axis direction of the base is the axis, and the third coil 12 is the base. It is wound so that the Z-axis direction is the axis. The base 20 is made of ferrite.

The base 20 has a flat and substantially rectangular parallelepiped shape, and an ear-shaped member 21 is provided at each of the eight corners of the base 20 which is a rectangular parallelepiped. The planar shape of the ear-shaped member 21 is formed into a fan shape of a quarter circle. On the surface of the base 20, the base 2
A second groove portion 22 that is deepest in the X-axis direction when 0 is installed in a flat state is formed, and the second coil 6 is wound around the second groove portion 22. Second side 21 of ear 21
b is arranged so as to be the side wall of the second groove portion 22.

A first groove portion 23 is formed on the surface of the base portion 20 in the Y-axis direction when the base portion 20 is installed in a flat state, and the first coil 5 is wound around the first groove portion 23. It The first side portion 21 a of the ear-shaped member 21 has a first groove portion 23.
It is arranged so that it will be the side wall of. The base portions of the two ear-shaped members 21 arranged such that the flat portions face each other are
The third groove 24 is formed, and the portion 21c sandwiched by the flat surfaces of the ear-like member 21 is oriented so as to be the side wall of the groove 24 of h3 around which the third coil 12 is wound.

The second coil 6 is wound around the base portion 20 having the above-described structure, and then the first coil 5 is wound in a direction orthogonal to the second coil 6, and the third coil 6 is wound. The coil 12 is wound along the peripheral surface. The antenna coil in this state is set in a resin case 30 as shown in FIG.

The case 30 has a shape in which a flat, generally quadrangular prism is placed flat and a disk-shaped hole is formed from the upper surface, for example. The hole has a size such that the antenna coil shown in FIG. 10 can be installed. Further, in the two pairs of facing side surfaces of the flat rectangular prism, the side surface central portion is cut out. At the four corners of the flat rectangular column, one end side of the plate-shaped terminals 31a to 31d provided on the back surface of the case 30 is embedded so as to project, and the other end side is attached to the side surface of the case 30. ing.

The first coil 5, the second coil 6 and the third coil
Is exposed in a state in which the base 20 around which the coil 12 is wound is arranged in the hole of the case 30 (in FIG. 11, the coil is not wound but is actually wound). A lid 32 made of resin is attached to the four ear-shaped members 21. The lid 32 is substantially the same in planar shape as the ear-like member 21, and is provided with a flat plate-shaped terminal 33.

Any one of the terminal ends of the first coil 5, the second coil 6 and the third coil 12 is wound around the predetermined one terminal 33, and the remaining three terminals are wound. The remaining end portion of the first coil 5, the remaining end portion of the second coil 6, and the remaining end portion of the third coil 12 are entwined with the terminal 33 in a one-to-one correspondence. The end of the coil is wound and the terminals 32 and the protruding portions of the corresponding terminals 31a to 31d are soldered to obtain an electrical connection. The invisible back surface of the case 30 in FIG. 11 is soldered and mounted on the circuit board, and the invisible surface is the upper surface.

12 and 13 show the third and third aspects of the present invention.
A configuration example of a receiving circuit configured using the antenna coil according to the fourth embodiment is shown. In the following description, the suffix “S” will be the winding start side end of the coil and the suffix “F” will be the winding end side end of the coil. First, the configuration example of FIG. 12 will be described. Second
The winding end side XF of the coil 6, the winding start side terminal YS of the first coil 5 and the winding start side terminal ZS of the third coil 12 are connected to the common terminal COM, and the winding start side of the second coil 6 is started. Each of the side end XS, the winding end YF of the first coil 5 and the winding end ZF of the third coil 12 is connected to a separate terminal. The common terminal COM is grounded.

Amplifiers 41a to 41c are provided, and one of the input ends of the amplifiers 41a to 41c is grounded. The non-grounded input end of the amplifier 41a is connected to the winding start side end XS of the second coil 6. The non-grounded input end of the amplifier 41b is connected to the winding end YF of the first coil 5. The non-grounded input end of the amplifier 41c is connected to the winding end ZF of the third coil 12.

Capacitors C are connected between the ground-side input ends and the non-ground-side input ends of the amplifiers 41a to 41c, respectively. The output terminals of the amplifiers 41a to 41c are connected to the reception selection means 42 such as a wireless device. The reception selection means 42 selects the largest signal from the signals output from the output terminals of the amplifiers 41a to 41c.

Also in the fourth embodiment, the number of windings of each coil is adjusted, and the first coil 5, the second coil 6 and the third coil 12 form independent tuning circuits. However, each tuning circuit is a high frequency amplifier circuit (amplifier 41a
To 41c), the high-frequency amplifier circuit amplifies and selectively selects a stronger output signal of each tuning circuit. The high-frequency amplifier circuit amplifies and selects the output signal of the tuning circuit formed by the first coil 5 for radio waves entering from the X-axis direction,
The output signal of the tuning circuit formed by the second coil 6 is amplified and selected for the radio wave entering from the Y-axis direction, and the third coil 12 forms the radio wave entering from the Z-axis direction. Amplify and select the output signal of the tuning circuit. Thus, also in the fourth embodiment, the antenna coil has the X axis,
It is possible to improve the reception sensitivity even with respect to the radio waves incident from the Y axis and Z axis directions.

Next, the configuration example of FIG. 13 will be described. In the configuration example of FIG. 12, the capacitor C is the amplifier 4
1a to 41c are respectively connected between the ground-side input ends and the non-ground-side input ends, but in the configuration example of FIG. 13, the capacitor C is connected in parallel to the second coil 6, The capacitor C is connected in parallel to the first coil 5,
The capacitor C is connected in parallel with the third coil 12.

The respective input ends of one of the amplifiers 41a to 41c are commonly connected and grounded, and the end XF on the winding end side of the second coil 6, the end YS on the winding start side of the first coil 5 and the third end. The winding start side end ZS of the coil 12 is a common terminal COM.
Is connected to the common connection terminal of the amplifiers 41a to 41c. With this configuration as well, similar to the configuration of FIG. 12, the antenna coil can selectively improve the reception sensitivity with respect to the radio waves incident from the X-axis, Y-axis, and Z-axis directions.

As shown in FIGS. 12 and 13, the end of each coil is connected to the common terminal COM on the antenna coil side. In this case, in the examples shown in FIGS. 12 and 13, the winding end side end XF of the second coil 6, the winding start side end YS of the first coil 5 and the winding start side end ZS of the third coil 12 are set. It was connected to the common terminal COM. Terminals that can be connected to the common terminal are terminal XF terminal XS in the second coil 6, terminal YF and terminal YS in the first coil 5, and terminal ZF in the third coil 12.
There is a terminal ZS. As shown in FIGS. 12 and 13, when the terminal XF, the terminal YS, and the terminal ZS are selected and the suffix is expressed as FSS, any terminal is 3
There are 2 3 = 8 combinations of combinations.

When describing the above eight types with suffixes, SSS, FFF, FFS, FSF, FS
S, SFF, SFS, and SSF. A test of which of the eight types has the preferable reception sensitivity characteristic is performed by measuring the frequency characteristic.
As shown in the above, FSS, which is an example in which the terminal XF, the terminal YS, and the terminal ZS are selected, is most preferable.

That is, the left side shows the frequency characteristic for the radio wave incident from the X-axis direction, the center shows the frequency characteristic for the radio wave incident from the Y-axis direction, and the right side shows the frequency characteristic for the radio wave incident from the Z-axis direction. In the case of the FSS, as shown in FIG. 14, the impedance value at the resonance frequency, which is the peak portion of the graph, is the highest and stable, and the frequency characteristics are almost the same in any axial direction. It can be seen that the reception sensitivity becomes good. In each chart, the vertical axis is impedance, one scale is 50 KΩ, and the horizontal axis is frequency.
Center of the horizontal axis is 134.2 KHz, width of the horizontal axis is 30 KHz
Is. The number of turns of each coil is 400, and the base 2
Has a diameter of 9 mm and the thinnest part has a thickness of 0.9
Mm, the thickness of the thickest part including the ear-like member 21 is 2.8 mm, and the capacitance of the capacitor C is 200 p.
It was set to F.

In contrast to the above, for example, in the case of FFS, as shown in FIG. 15, there are variations in the resonance frequency and the impedance value in the X-axis direction, the Y-axis direction, and the Z-axis direction. Inappropriate characteristics such as crushing of a peak portion caused by interference with other coils are observed in the direction and the Z-axis direction. Examples of common connections other than FFS except FSS were almost the same as FFS, and it was difficult to obtain characteristics aligned in the three-axis directions and inappropriate frequency characteristics were observed.

In the above description, an example in which the ear-shaped member 21 is provided on the base 20 has been shown, but basically, the bobbin 50 shown in FIG. 16 can be used. That is, the bobbin 50 includes a base portion 51 having a flat columnar shape, a first groove 52 provided for winding the first coil so that the X-axis direction of the base portion 51 serves as an axis, and The second groove 53 is provided for winding the third coil so that the Z axis direction of the base portion 51 serves as an axis. The four rod-shaped members 54 extending in a long shape in the Y-axis direction of the base portion 51 form the base portion 5.
It is provided along the four sides of 1. The second coil is wound so as to cross the rod-shaped member 54. That is, the second coil is wound so that the winding axis direction becomes the Y axis. In FIG. 16, the first, second and third coils are not shown. With the antenna coil having such a configuration, the same effect as that of the antenna coil according to the fourth embodiment can be obtained. Further, the ferrite core 2 in each of the above embodiments may be changed to, for example, a resin core, and the material of the base portions 20 and 51 is not limited to ferrite, and a resin or the like can be used.

[0031]

As described above, according to the antenna coil of the present invention, the coil is wound in the X-axis Y-axis direction of one core or base, or in the X-axis Y-axis and Z-axis directions. Therefore, compared to the case where a plurality of bar antenna coils are assembled to form an antenna coil, the size can be made smaller, and the receiving sensitivity to the radio waves incident from three orthogonal directions can be selected, so that the antenna coil can be installed at the installation position. Regardless, it is possible to make the reception sensitivity suitable. Furthermore,
Connect one of the terminals of the three coils in common,
It is possible to improve the reception sensitivity.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of an antenna coil of the present invention.

FIG. 2 is a plan view of the first embodiment of the antenna coil of the present invention.

FIG. 3 is a perspective view showing an example of the shape of a ferrite core used in the antenna coil according to the first embodiment of the present invention.

FIG. 4 is a perspective view showing a second embodiment of the antenna coil of the present invention.

FIG. 5 is a plan view of a second embodiment of the antenna coil of the present invention.

FIG. 6 is a perspective view showing an example of the shape of a ferrite core used in the second embodiment of the antenna coil of the present invention.

FIG. 7 is a perspective view of a third embodiment of the antenna coil of the present invention.

FIG. 8 is a perspective view of a third embodiment of the antenna coil of the present invention.

FIG. 9 is a perspective view showing a base portion of an antenna coil according to a fourth embodiment.

FIG. 10 is a perspective view showing a base portion around which a coil of an antenna coil according to a fourth embodiment is wound.

FIG. 11 is a perspective view showing a state in which a base portion around which the coil of the antenna coil according to the fourth embodiment is wound is set in a case.

FIG. 12 is a configuration diagram of a receiving circuit configured using the antenna coil according to the fourth embodiment.

FIG. 13 is a configuration diagram of a receiving circuit configured using the antenna coil according to the fourth embodiment.

FIG. 14 is a diagram showing a frequency characteristic when the antenna coil according to the fourth embodiment has the best connection when one predetermined end of each coil is commonly connected.

FIG. 15 is a diagram showing frequency characteristics when the antenna coil according to the fourth embodiment has a connection other than the best connection when a predetermined one end of each coil is commonly connected.

FIG. 16 is a perspective view showing a base portion of the antenna coil according to the fifth embodiment.

[Explanation of symbols]

1 antenna coil 2 Ferrite core 3 winding part 4a to 4h protrusion 5 First coil 6 Second coil 7 Electrode part 8 reels 9 holes (or recesses) 10 walls 11a, 11b collar part 12 Third coil 13 1st antenna coil part 20 base 21 ear members 22 Second groove 23 First Groove 24 Third groove 30 cases 31a to 31d terminals 32 lid 33 terminals 41a-41c amplifier 42 Receiving means 50 bobbins 51 base 52 first groove 53 Second groove 54 Bar-shaped member

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01Q 21/28 H01Q 21/28 (72) Inventor Ryumi Nishino 3-3 Nihonbashi Ningyocho, Chuo-ku, Tokyo No. 6 Sumida Technologies Co., Ltd. F-term (reference) 2E250 AA21 BB08 BB38 CC20 FF23 FF24 FF27 FF36 HH01 JJ00 JJ03 KK03 5E070 AA01 AB01 CA12 CA13 CA20 5J021 AA02 AA03 AA12 AB04 CA06 DB05 FA26 FA31 GA03 HA06 HA06 HA10 HA06 HA10

Claims (9)

[Claims] 1. An antenna coil, wherein a first coil and a second coil are wound around a winding frame portion of a core so that their winding axes are orthogonal to each other. 2. A third coil is arranged so as to surround the first coil and the second coil, and to wind the winding coil so that the winding axis is orthogonal to the two coils. The antenna coil according to Item 1. 3. The antenna coil according to claim 2, wherein the third coil is wound around a winding frame having an insulating property. 4. The number of windings of each coil is adjusted so that the electric field strength or the magnetic field strength induced in each coil is substantially equal. The antenna coil according to claim 1. 5. A base having a flat columnar shape, a first coil wound so that the X-axis direction of the base becomes an axis, and a Y-axis direction of the base is wound as an axis. A second coil that is wound, and a third coil that is wound so that the Z-axis direction of the base is an axis, and each winding that winds the first, second, and third coils The road is
An antenna coil, characterized in that at least a part thereof is formed as a groove. 6. The base portion has a flat and substantially rectangular parallelepiped shape, and an ear-shaped member is provided at an octagonal corner of the base portion of the rectangular parallelepiped body, and the first side portion of the ear-shaped member is wound by the first coil. The second side part of the ear-shaped member is arranged so as to be the side wall of the first groove part that is wound, and the second side part of the ear-shaped member is arranged so as to be the side wall of the second groove part where the second coil is wound. The antenna coil according to claim 5, wherein the portion sandwiched by the flat surfaces of the ear-shaped member is oriented so as to be a side wall of a third groove around which the third coil is wound. 7. The planar shape of the ear-shaped member is formed into a fan shape of a quarter circle.
Antenna coil according to. 8. One of the end portions of each coil.
The antenna coil according to any one of claims 1 to 7, wherein one terminal is connected to a common terminal, the remaining three ends are connected to different terminals, and four terminals are provided. 9. A winding end side end portion of the first coil, a winding start side end portion of the second coil, and a winding start side end portion of the third coil are connected to the common terminal. The antenna coil according to claim 8, wherein the antenna coil is formed.