JP6089446B2 - Antenna device and communication terminal device - Google Patents

Description

  The present invention relates to an antenna device that is used for non-contact communication and includes at least a coil antenna and a booster antenna, and a communication terminal device including the antenna device.

  Hereinafter, a conventional antenna device described in Patent Documents 1 and 2 will be described with reference to FIG. In FIG. 16, the antenna device 51 is used for non-contact communication (NFC (Near Field Communication) or FeliCa) of 13.56 MHz band, for example, and includes a coil antenna 52 and a booster antenna 53 provided above the coil antenna 52. The coil antenna 52 is connected in parallel to the integrated circuit together with a capacitor (not shown), and includes at least a magnetic core 54 and a first coil conductor 55. The booster antenna 53 includes at least a second coil conductor 56.

  In the coil antenna 52, the magnetic core 54 has a substantially rectangular parallelepiped shape and has a circumferential surface F75 parallel to the first winding axis A61. The first coil conductor 55 is formed on the peripheral surface F75 so as to be spirally wound around the first winding axis A61.

  In the booster antenna 53, the second coil conductor 56 is a planar coil conductor provided, for example, on an insulating sheet material so as to be wound around the second winding axis A62 in a spiral shape. Such a second coil conductor 56 forms a parallel resonance circuit with a capacitor (not shown).

  The coil antenna 52 is disposed below the second coil conductor 56 so that the first and second winding axes A61 and A62 are substantially orthogonal to each other. During data communication, a high frequency signal (13.56 MHz band carrier wave modulated by transmission data) is applied to the coil antenna 52 from the integrated circuit, and a high frequency current flows. As a result, a magnetic field interlinking with the second coil conductor 56 is generated in the vicinity of the coil antenna 52. By this magnetic field coupling, an induced current flows through the second coil conductor 56, and the second coil conductor 56 also induces a magnetic field. The magnetic field of the second coil conductor 56 is magnetically coupled to the communication partner antenna, thereby performing data communication.

JP 2008-306869 A Japanese Patent No. 4325621

  However, as shown in FIGS. 17A and 17B, both antennas 52 and 53 overlap when viewed from above. Both antennas 52 and 53 are capacitively coupled by stray capacitance (parasitic capacitance) generated in the overlap portion. Due to the influence of this capacitive coupling, the resonance frequencies of both antennas 52 and 53 are shifted, and their antenna characteristics are degraded.

  Further, due to the recent thinning of mobile phones, both antennas 52 and 53 are arranged close to each other, so that a large stray capacitance is likely to occur. Therefore, for example, if the positional relationship between the two antennas 52 and 53 changes depending on the mounting accuracy of the coil antenna 52 as shown in FIGS. There is a case.

  As can be seen from the above, the antenna characteristics of the conventional antenna device may vary greatly due to the influence of stray capacitance. Note that this problem is not limited to a mobile phone, and may occur in a communication terminal device (for example, a tablet terminal) provided with the antenna device.

  Therefore, an object of the present invention is to provide an antenna device capable of suppressing variations in antenna characteristics and a communication terminal device including the antenna device.

  In order to achieve the above object, one aspect of the present invention provides an antenna device, which includes a coil antenna including a reference surface and a first coil conductor wound around a surface facing the reference surface, and a winding on the main surface. A booster antenna including a second coil conductor to be rotated.

  In the coil antenna and the booster antenna, a portion of the first coil conductor on the reference surface is opposed to the second coil conductor through a space, and the facing portion is planar from the normal direction of the reference surface. When viewed, the current direction of the second coil conductor and the direction of current flowing through the portion on the reference plane in the first coil conductor are not parallel or perpendicular to each other.

  The antenna device is mounted on, for example, a communication terminal device.

  According to the above aspect, even if the mounting accuracy of the coil antenna or the booster antenna varies, it is possible to suppress the variation in the area of the overlap portion between the first coil conductor and the second coil conductor in the plan view. Thereby, the characteristic dispersion | variation for every antenna apparatus can be suppressed.

It is a schematic diagram which shows the structure of the communication terminal device which concerns on one Embodiment of this invention. It is an equivalent circuit diagram of a feed circuit and a booster antenna. It is a perspective view of the coil antenna of FIG. FIG. 4 is an exploded view of the coil antenna of FIG. 3. It is a perspective view which shows the core which consists of a some magnetic body layer. It is a schematic diagram which shows the detailed structure of the booster antenna of FIG. (A), (b) is a schematic diagram which shows the effect by the presence or absence of the magnetic body sheet material of the booster antenna of FIG. (A) is a top view of the antenna apparatus of FIG. 1, and (b) is a top view of the antenna apparatus when the mounting position of the coil antenna is shifted. It is a side view of the antenna apparatus of FIG. (A), (b) is a schematic diagram which shows the even mode and odd mode in an antenna apparatus. It is a top view which shows the 1st modification of the antenna apparatus of FIG. (A) is a perspective view of the 2nd modification of the antenna apparatus of FIG. 1, (b) is a side view of the figure (a), (c) is a 3rd modification of the antenna apparatus of FIG. It is a side view. It is a perspective view which shows the modification of a coil antenna. It is an exploded view of the coil antenna of FIG. (A)-(c) is a figure which shows the other modification of a booster antenna. It is a schematic diagram which shows the structure of the conventional antenna apparatus. It is a top view which shows the problem of the antenna device of FIG.

(Embodiment)
Prior to description of an antenna device and a communication terminal device according to an embodiment of the present invention, first, the X-axis, Y-axis, and Z-axis shown in FIGS. 1 to 10 are defined as follows. The X-axis, Y-axis, and Z-axis indicate the left-right direction (lateral direction), front-rear direction (vertical direction), and vertical direction (height direction or thickness direction) of the coil antenna shown in FIG.

(Configuration of communication terminal device)
First, the configuration of the communication terminal device 1 according to the present embodiment will be described. FIG. 1 shows an internal configuration of the housing 5 when the housing cover 3 of the communication terminal device 1 is opened. The communication terminal device 1 is a mobile phone or the like, and includes at least a printed wiring board 7 and an antenna device 9 and an integrated circuit 11 for non-contact communication using NFC or the like in addition to the housing cover 3 and the housing 5. Prepare. The antenna device 9 includes at least a coil antenna 13 and a booster antenna 15. In addition to the above, the communication terminal device 1 is mounted with integrated circuits, electronic components, battery packs, etc. for voice calls in high density. Is omitted.

  The printed wiring board 7 is provided inside the housing 5, and at least the integrated circuit 11 and the coil antenna 13 are mounted on the printed wiring board 7. In the printed wiring board 7, the size in the X-axis direction is about 110 mm, for example, and the size in the Y-axis direction is about 50 mm, for example.

  As shown in FIG. 2, a coil antenna 13 and a capacitor 17 (not shown in FIG. 1) are connected to the integrated circuit 11 in parallel. The integrated circuit 11, the coil antenna 13, and the capacitor 17 constitute a power feeding circuit 19. Here, assuming that the inductance value of the coil antenna 13 is L1 and the capacitance value of the capacitor 17 is C1, the resonance frequency of the parallel resonance circuit is substantially determined by L1 and C1. FIG. 2 also shows the capacitive component of the coil antenna 13. In addition, a matching circuit may be connected between the coil antenna 13 and the integrated circuit 11 as necessary.

  Reference is now made to FIGS. The coil antenna 13 includes a magnetic core 131, a first coil conductor 133, an insulator layer 135, a first external electrode 137a, a second external electrode 137b, a first via electrode 139a, and a second via electrode 139b. And.

  The magnetic core 131 is made of, for example, a magnetic material having a predetermined permeability μa (for example, about 100). The magnetic core 131 has a substantially rectangular parallelepiped shape, and more specifically, a circumferential surface Fs substantially parallel to the first winding axis A1 parallel to the Y axis and orthogonal to the first winding axis A1. It consists of a front end face and a rear end face. The peripheral surface Fs includes a reference surface F11, a facing surface F12, a left side surface F13, and a right side surface F14. In the present embodiment, the reference surface F11 is an upper surface, the opposing surface F12 is a lower surface, and these are opposed in the vertical direction. The magnetic core 131 has a size of about 2.0 mm to 3.0 mm in the X axis direction, about 3.2 mm to 6.0 mm in the Y axis direction, and about 0.7 mm to 1.0 mm in the Z axis direction. .

  The magnetic core 131 may be manufactured as a block body having the above size from the beginning without being stacked, but may be manufactured by stacking a plurality of magnetic layers 131a as shown in FIG. I do not care. In FIG. 5, for the sake of convenience, only the two magnetic layers are denoted by reference numeral 131a. Further, the thicknesses of the magnetic layers 131a may be the same as each other or not. Thus, by comprising with the some magnetic body layer 131a, the height of the magnetic body core 131 can be adjusted easily, and also brittleness can be suppressed.

  Reference is again made to FIG. 3 and FIG. The first coil conductor 133 is made of a conductive material (for example, silver) and constitutes a helical coil. Specifically, the first coil conductor 133 is formed on the circumferential surface Fs so as to wind around the first winding axis A1. The number of turns is 4, for example. More specifically, the first coil conductor 133 includes first to fourth conductor patterns 133a to 133d for each turn. The first conductor pattern 133a is formed on the facing surface F12, and the third conductor pattern 133c is formed on the reference surface F11. The second and fourth conductor patterns 133b and 133d are formed on the right side surface F14 and the left side surface F13. For convenience of illustration, reference numerals 133a to 133d are attached only to the first to fourth conductor patterns for one turn.

  The first conductor pattern 133a of each turn is substantially perpendicular to the first winding axis A1 in a plan view from the normal direction of the reference plane F11, and the third conductor pattern 133c of each turn is the same plane. It is formed so as not to be orthogonal to the first winding axis A1 when viewed. In other words, each first conductor pattern 133a has a non-parallel positional relationship with each third conductor pattern 133c in the same plan view. Moreover, each 3rd conductor pattern 133c has a positional relationship parallel to the 3rd conductor pattern 133c of the turn adjacent to self.

  The insulator layer 135 is made of an insulating material and has at least a joint surface F21 and a back surface F22. A magnetic core 131 on which the first coil conductor 133 is formed is laminated on the bonding surface F21. The back surface F22 faces the joint surface F21 in the up-down direction. A first external electrode 137a and a second external electrode 137b are formed on the front end portion and the rear end portion of the back surface F22. The coil antenna 13 and the integrated circuit 11 (see FIG. 1 and the like) are electrically connected by using the first and second external electrodes 137a and 137b.

  In the insulator layer 135, a through hole penetrating from the back surface F22 to the bonding surface F21 is formed above the first external electrode 137a, and a first via electrode 139a is formed in the through hole. Similarly, a second via electrode 139b is formed in the insulator layer 135 immediately above the second external electrode 137b. One end and the other end of the first coil conductor 133 are connected to the first and second via electrodes 139a and 139b.

  Reference is again made to FIG. The booster antenna 15 is attached to the inside of the housing cover 3, for example. As shown in FIG. 6, the booster antenna 15 includes an insulating sheet material 151 made of an insulating material, two second coil conductors 152 and 153, and a magnetic sheet material 154.

  Each of the second coil conductors 152 and 153 is made of a conductive material (for example, silver) and forms a so-called planar spiral coil. The second coil conductors 152 and 153 have a size of about 38 mm in the X-axis direction, about 40 mm in the Y-axis direction, and about 0.05 mm in the Z-axis direction. The line width is about 0.2 mm to 1.0 mm, and the distance between the lines is 1.0 mm. The number of turns of the second coil conductors 152 and 153 is three.

  In the present embodiment, the second coil conductor 152 is formed on the first main surface (front surface) of the insulating sheet material 151, and the second coil conductor 153 is formed on another first main surface (back surface) of the insulating sheet material 151. . The second coil conductors 152 and 153 are formed to wind in opposite directions. More specifically, the second coil conductors 152 and 153 are wound around a second winding axis A2 parallel to the Z axis. The second coil conductor 153 has a symmetrical shape with the second coil conductor 152 with respect to the longitudinal center plane Fv. The vertical center plane Fv includes the second winding axis A2 and is a plane parallel to the ZX plane.

  The magnetic sheet material 154 is made of a magnetic material having a predetermined magnetic permeability μb (for example, about 130), and is attached to the back surface of the insulating sheet material 151. The size in the X-axis direction and the Y-axis direction is, for example, about 40 mm, and the size (thickness) in the Z-axis direction is, for example, about 0.1 mm.

  When this magnetic sheet material 154 is not present, the magnetic flux (dotted arrow) from the communication partner collides with the printed wiring board 7 as shown in FIG. As a result, an eddy current is generated in the printed wiring board 7, or magnetic flux is unnecessarily coupled to the electronic components mounted on the printed wiring board 7. As a result, the communication characteristics of the communication terminal device 1 deteriorate. On the other hand, when the magnetic sheet material 154 is present, the magnetic flux passes through the inside of the magnetic sheet material 154 and does not reach the printed wiring board 7 as shown in FIG. Thereby, the deterioration of the communication characteristics of the communication terminal device 1 as described above can be prevented.

  Further, a line capacitance is generated between the second coil conductors 152 and 153. Therefore, as shown in the equivalent circuit diagram of FIG. 2, the second coil conductors 152 and 153 are equivalently connected via the capacitors 155 and 156. Here, assuming that the inductance values of the second coil conductors 152 and 153 are L2 and L3, and the capacitance values of the capacitors 155 and 156 are C2 and C3, the resonance frequency of the booster antenna 15 is substantially L2, L3, C2, and so on. Determined by C3.

(Detailed arrangement relationship between coil antenna and booster antenna)
The coil antenna 13 and the booster antenna 15 are disposed so as to satisfy at least the following conditions (1) to (3).
Condition (1): At the time of data communication, as shown in FIG. 8A, in the plan view from the normal direction of the reference plane F11, the direction of the current flowing through the third conductor pattern 133c, the second coil conductor 152, The direction of the current flowing through 153 is not orthogonal or parallel.
Condition (2): As shown in FIG. 9, the second coil conductors 152 and 153 and the third conductor pattern 133c are opposed to each other through a space.
Condition (3): As shown in FIG. 9, the coil antenna 13 is mounted on the printed wiring board 7 so that the facing surface F <b> 12 is close to the printed wiring board 7.

(Operation of contactless communication device)
First, data transmission to a communication partner will be described. The integrated circuit 11 (see FIG. 2) modulates a 13.56 MHz carrier wave with data to be transmitted (baseband signal) to generate a high-frequency signal. The resonance frequency of the parallel resonance circuit of the power feeding circuit 19 is set to 13.56 MHz, and the integrated circuit 11 applies the generated high-frequency signal (high-frequency current) to the coil antenna 13 and the capacitor 17 to resonate. When transmitting data, the coil antenna 13 induces a magnetic field (indicated by a one-dot chain line in FIG. 9) in the vicinity of the coil antenna 13 by a high-frequency current from the integrated circuit 11. The magnetic field from the coil antenna 13 links the booster antenna 15. As a result, the coil antenna 13 and the booster antenna 15 are magnetically coupled, and an induced current flows through the second coil conductors 152 and 153. Due to this induced current, the booster antenna 15 generates a magnetic field (indicated by a two-dot chain line in FIG. 9). Here, since the size of the booster antenna 15 is larger than that of the coil antenna 13, the magnetic field generated by the booster antenna 15 has a large strength, and thus the communication distance is secured as the antenna device 9. .

  Next, data reception from a communication partner will be described. When the magnetic field generated on the communication partner side links the booster antenna 15, an induced current flows through the second coil conductors 152 and 153. Due to this induced current, the booster antenna 15 generates a magnetic field. The magnetic field of the booster antenna 15 links the first coil conductor 133. As a result, the coil antenna 13 and the booster antenna 15 are magnetically coupled, and an induced electromotive force is generated between the first and second external electrodes 137a and 137b (see FIG. 3) of the coil antenna 13, and the integrated circuit 11 A high-frequency current (high-frequency signal) flows through. The integrated circuit 11 performs data reproduction by demodulating the received high-frequency signal.

(Operation and effect of the embodiment)
17A and 17B, when the mounting position of the coil antenna 52 is changed, the conductor portion adjacent to the second coil conductor 56 in the first coil conductor 55 in plan view from above. Enters between the lines of the second coil conductor 56 or overlaps the second coil conductor 56. Therefore, the change in the area of the overlap portion between the coil conductors 55 and 56 is relatively large.

  On the other hand, in the present embodiment, during data communication, each coil antenna 13 can be moved in parallel on the printed wiring board 7 as shown by lattice hatching in FIGS. 8 (a) and 8 (b). The third conductor pattern 133c of the turn does not completely enter between the lines of the second coil conductors 152 and 153. Therefore, the change in the area of the overlap portion between the third conductor pattern 133c and the second coil conductors 152 and 153 can be made smaller than in the conventional case. In other words, even if the positional relationship between the antennas 13 and 15 varies due to the mounting accuracy of the coil antenna 13, the variation in the area change of the overlap portion is reduced. Therefore, a large difference does not occur in the stray capacitance generated during data communication for each antenna device 9. As a result, variations in antenna characteristics can be suppressed.

  Further, even mode or odd mode occurs in the antenna device 9 during data communication. More specifically, in the even mode, as shown in FIG. 10A, the current I1 that flows through the coil antenna 13 and the current I2 that flows through the booster antenna 15 with reference to the stray capacitance (that is, the capacitive coupling portion) Cs. And maintain a symmetrical relationship. In this case, since a potential difference does not occur between the stray capacitances Cs, the stray capacitance Cs does not substantially affect the resonance frequency of the power feeding circuit 19 and the resonance frequency of the booster antenna 15.

  On the other hand, in the odd mode, as shown in FIG. 10B, the current I1 flowing through the coil antenna 13 and the current I2 flowing through the booster antenna 15 are asymmetric with respect to the stray capacitance Cs. In this case, since a potential difference is generated between the stray capacitances Cs, the resonance frequency of the power feeding circuit 19 and the resonance frequency of the booster antenna 15 are greatly affected. The odd mode occurs due to complex factors such as the feeding circuit 19, the booster antenna 15, and the resonance frequency of the communication counterpart. In other words, we do not know when the odd mode occurs. Therefore, as in this embodiment, by suppressing the variation in stray capacitance, the influence of stray capacitance on each resonance frequency in the odd mode can be suppressed as much as possible.

  As for the first conductor pattern 133a, as shown in FIG. 8 (a) and FIG. 8 (b), the change in the area of the overlapping portion with the second coil conductors 152 and 153 is shown by hatching. Is relatively large. However, the magnetic field from the first conductor pattern 133a does not radiate into the space compared to the magnetic field from the third conductor pattern 133c due to the influence of the printed wiring board 7 having a large non-permeability. Further, the distance between the first conductor pattern 133a and the second coil conductors 152 and 153 is relatively large. Further, the first conductor pattern 133a is close to the ground. From the above, the influence of stray capacitance that can occur between the second coil conductors 152 and 153 and the first conductor pattern 133a is relatively small.

  Further, as described above, in recent years, the coil antenna 13 and the booster antenna 15 are arranged close to each other. Thereby, the first coil conductor 133 and the second coil conductors 152 and 153 are strongly inductively coupled. Also by inductive coupling, the resonance frequency of the feeding circuit 19 or the booster antenna 15 varies greatly depending on the mounting accuracy of the coil antenna 13. However, by arranging the coil antenna 13 and the booster antenna 15 as in the condition (1), variations in these inductive couplings can be suppressed.

(First modification of antenna device)
In the above embodiment, in the antenna device 9, the third conductor pattern 133c on the coil antenna 13 side is not orthogonal to the first winding axis A1. However, the present invention is not limited thereto, and as shown in FIG. 11, the third conductor pattern 133c on the reference plane F11 may be orthogonal to the first winding axis A1. In this case, the booster antenna 15 is arranged such that the second coil conductors 152 and 153 are not parallel or orthogonal to the third conductor pattern 133c in plan view from the Z-axis direction.

(Second modification of antenna device)
In the above embodiment, in the antenna device 9, the second coil conductors 152 and 153 are formed as flat spiral coils on one and the other of the first main surfaces of the insulating sheet material 151. However, the present invention is not limited to this. For example, the second coil conductor 152 may be formed on the first main surface F41 and the second main surface F42 as shown in FIGS. 12 (a) and 12 (b). Here, the second main surface F42 shares at least one side and intersects with the first main surface F41. The same applies to the second coil conductor 153. In the example of FIGS. 12A and 12B, the second main surface F42 is bent by 90 ° in the direction of the printed wiring board 7 with respect to the first main surface F41. In this case, as shown in FIG. 12B, the coil antenna 13 may be arranged such that the reference plane F11 faces the second main surface F42. However, as in the above embodiment, the third conductor pattern 133c and the second coil conductors 152 and 153 on the second main surface F42 are not parallel or perpendicular to each other in plan view from the normal direction of the reference plane F11. In addition, the coil antenna 13 and the booster antenna 15 are arranged.

  Moreover, as shown in FIG.12 (c), the 2nd main surface F42 may be bent at an angle other than 90 degrees in the direction of the printed wiring board 7 on the basis of the 1st main surface F41. Further, the insulating sheet material 151 may be curved.

(First modification of coil antenna)
Further, the coil antenna 13 may be configured as shown in FIGS. 13 and 14. In FIG. 13 and FIG. 14, the coil antenna 13 has a magnetic core 231, a first coil conductor 233, a base material layer 235, and a magnetic core 131 instead of the magnetic core 131 and the first coil conductor 133. The third coil conductor 237 is different in that the third coil conductor 237 is provided. Since there is no difference other than that, in FIG. 13 and FIG. 14, the thing equivalent to the structure of FIG. 3 and FIG. 4 is attached with the same referential mark, and each description is abbreviate | omitted.

  The magnetic core 231 is made of a magnetic material having a relatively high magnetic permeability μc (for example, about 130). As such a magnetic material, there is Ni—Zn—Cu based ferrite. Similarly to the magnetic core 131, the magnetic core 231 has a peripheral surface Fs including a reference surface F51, a facing surface F52, a left side surface F53, and a right side surface F54. Further, the sizes of the magnetic core 231 in the X-axis, Y-axis, and Z-axis directions may be the same as or different from those of the magnetic core 131.

  The first coil conductor 233 has first to fourth conductor patterns 233a to 233d for each turn, like the first coil conductor 133.

The base material layer 235 is made of, for example, an insulating material. The magnetic permeability μd of the insulator is close to the magnetic permeability μ ₀ in vacuum or air, and is smaller than the magnetic permeability μc of the magnetic core 231. The base material layer 235 is laminated on the reference plane F31 on which the first coil conductor 233 is formed, and has a predetermined thickness in the vertical direction. This thickness is sufficiently small with respect to the height of the magnetic core 231 and is, for example, 100 μm to 1000 μm. The size of the base material layer 235 in the X-axis direction and the Y-axis direction is substantially the same as that of the magnetic core 131.

  As clearly shown in FIG. 14, the base material layer 235 has a joint surface F61, an upper surface F62, a left side surface F63, and a right side surface F64. The joint surface F61 and the upper surface F62 are substantially parallel to the XY plane. The joining surface F61 is in contact with the reference surface F51, and the upper surface F62 is opposed to the joining surface F61 in the vertical direction. The left side surface F63 and the right side surface F64 are surfaces that are substantially parallel to the YZ plane and connect the joint surface F61 and the upper surface F62.

  The base material layer 235 is not limited to an insulating material, and may be made of a dielectric material or a magnetic material having a magnetic permeability lower than the magnetic permeability μc. Further, the base material layer 235 may be made of a material having a relative permeability smaller than that of the magnetic core 231 at a use temperature (for example, 25 ° C.). Here, when the base material layer 235 is made of a magnetic material, Ni—Zn—Cu based ferrite is used in the same manner as the magnetic core 231. In this case, in order to reduce the magnetic permeability, a predetermined additive is mixed when the base material layer 235 is produced.

  The third coil conductor 237 is made of a conductive material such as silver, and includes first to third conductor patterns 237a to 237c corresponding to the number of turns of the first coil conductor 233. The first conductor pattern 237a is substantially parallel to the third conductor pattern 233c of the first coil conductor 233, and is formed on the upper surface F62 so as to overlap the third conductor pattern 233c in plan view from the normal direction of the reference plane F51. .

  The second and third conductor patterns 237b and 237c are formed on the left side surface F63 and the right side surface F64 so that one end and the other end of the first conductor pattern 237a are connected to one end and the other end of the third conductor pattern 233c. It is formed.

(Production method of this modification)
Next, an example of the manufacturing method of the coil antenna will be described. This manufacturing method includes the following steps (1) to (6).
(1) For example, the calcined ferrite powder is mixed with a binder, a plasticizer and the like by a ball mill so that a desired magnetic permeability μ can be obtained after sintering. The slurry obtained in this manner is molded so as to have a predetermined size during sintering by a doctor blade method or the like, and a first sheet material based on the magnetic core 231 is obtained.

  (2) In the first sheet material obtained in (1) above, through holes for the conductor patterns 233b and 233d are formed using a laser or a punching press, and an electrode made of, for example, silver is formed in the through holes. The paste is filled. Furthermore, electrode paste is screen printed on the surface of the first sheet material, and as a result, conductor patterns 233a and 233c are formed. A desired number of such first sheet materials are laminated.

  (3) Moreover, in order to produce the base material layer 235 and the insulator layer 135, the calcined ferrite powder is mixed with a binder, a plasticizer, and the like by a ball mill. The resulting slurry is molded by a doctor blade method or the like, and as a result, a second sheet material serving as a basis for the base material layer 235 and the insulator layer 135 is obtained.

  (4) The through holes for the first and second via electrodes 139a and 139b are formed in the second sheet material obtained in (3) above. The through holes are filled with an electrode paste to form the first and second via electrodes 139a and 139b. Further, the second sheet material on which the first and second via electrodes 139a and 139b are formed is sequentially pressure-bonded so as to have a desired thickness after sintering. Thereby, the insulator layer 135 is produced.

  (5) In addition, the second sheet material obtained in the above (3) is formed with through holes for the second and third conductor patterns 237b and 237c, and the through holes are filled with an electrode paste. Further, in the second sheet material, the first conductor pattern 237a is formed by screen-printing the electrode paste on the surface forming the upper surface F32. Such a second sheet material is sequentially pressed. Thereby, the base material layer 235 is produced.

  (6) The above-described insulator layer 135, magnetic core 231 and base material layer 235 are pressure-bonded together and baked at, for example, 900 ° C. for 2 hours, and then diced. As a result, the coil antenna 13 according to the modified example is obtained.

  In the present modification, the coil antenna 13 has been described as having a double coil conductor, but the present invention is not limited to this, and the coil antenna 13 may have a triple or more coil conductor.

(Appendix)
In the said embodiment, the booster antenna 15 was comprised so that it might resonate using the two 2nd coil conductors 152 and 153 and these line capacitances. However, the present invention is not limited to this, and the booster antenna 15 may be as shown below.

(Variations of booster antennas)
First, as shown in FIG. 15A, the booster antenna 15 may be one in which capacitor elements 253 are connected to both ends of one second coil conductor 251. Further, as shown in FIG. 15B, the booster antenna 15 has a second insulating sheet material 255 attached on the second coil conductor 152 and a third second coil conductor 257 formed thereon. It doesn't matter. Note that the number of the second coil conductors 257 may be any number. Further, as shown in FIG. 15C, the booster antenna 15 is not provided inside the housing cover 3, but the second coil conductors 259 and 261 are provided on the front and back surfaces of the housing cover 3 using the MID method or the like. May be drawn one by one to realize the booster antenna 15.

  The antenna device and the communication terminal device according to the present invention can reduce deterioration in characteristics of surrounding electronic components, and mainly at frequencies below the VHF band, such as a communication terminal device on which a non-contact communication system is mounted or a small radio. Suitable for small radios used.

DESCRIPTION OF SYMBOLS 1 Communication terminal device 9 Antenna apparatus 11 Integrated circuit 13 Coil antenna 131,231 Magnetic body core 131a Magnetic body layer 133,233 First coil conductor 235 Base material layer 237 Third coil conductor 15 Booster antenna 151 Insulation sheet material 152,153 251, 257, 259 Second coil conductor 154 Magnetic sheet material 255 Second insulating sheet material 19 Feed circuit A1 First winding axis A2 Second winding axis Fs Peripheral surface F11, F51 Reference surface F12, F52 Opposing surface

Claims (5)

A coil antenna including a reference surface and a first coil conductor wound around the reference surface;
A booster antenna including a second coil conductor wound on the main surface,
When the portion of the first coil conductor on the reference surface is opposed to the second coil conductor through a space, and the facing portion is viewed in plan from the normal direction of the reference surface, the second coil conductor The coil antenna and the booster antenna are arranged such that the current direction of the first coil conductor and the direction of current flowing through the portion on the reference plane in the first coil conductor are not parallel or perpendicular to each other.   2. The antenna according to claim 1, wherein the first coil conductor is wound so that a portion on the reference surface and a portion on the facing surface are not parallel when viewed in plan from the normal direction. apparatus.   The antenna device according to claim 1, wherein the coil antenna further includes a magnetic core having the reference surface and the facing surface.   The antenna device according to claim 3, wherein the magnetic core is formed by stacking a plurality of magnetic layers. An integrated circuit that generates a high-frequency signal modulated by transmission data or reproduces data from a received high-frequency signal;
A high frequency signal generated by the integrated circuit, or a coil antenna that outputs a received high frequency signal from space to the integrated circuit;
A booster antenna provided in the vicinity of the coil antenna;
The coil antenna includes a first coil conductor wound around a reference surface and a surface facing the reference surface,
The booster antenna includes a second coil conductor wound on a main surface;
In the coil antenna and the booster antenna, a portion of the first coil conductor on the reference surface is opposed to the second coil conductor through a space, and the facing portion is planar from the normal direction of the reference surface. The communication terminal device is arranged such that when viewed, the current direction of the second coil conductor and the direction of current flowing through the portion on the reference plane in the first coil conductor are not parallel or perpendicular to each other.

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