JP5834987B2 - ANTENNA DEVICE AND WIRELESS COMMUNICATION DEVICE - Google Patents

Description

  The present invention relates to an antenna apparatus adapted to a plurality of frequency bands and a radio communication apparatus including the antenna apparatus.

  In recent years, wireless communication devices such as mobile phone terminals are equipped with systems using various frequency bands (HF band, UHF band, etc.) such as NFC (Near Field Communication), GPS, and Bluetooth (registered trademark). In such a wireless communication device using a plurality of frequency bands, it is necessary to provide an antenna corresponding to each frequency band, but it is necessary to secure a space for installing a large number of antennas in a wireless communication device that is becoming smaller in size. Is getting more and more difficult.

  Patent Document 1 discloses an antenna device adapted to a plurality of frequency bands. The antenna device described in Patent Document 1 is an antenna having a spiral-shaped antenna (coil antenna) and a folded dipole structure. This antenna is set to a line length that allows communication at two frequencies of the HF band and the UHF band, and acts as a coil antenna in the HF band and as a dipole antenna in the UHF band.

Japanese Patent No. 4529786

  However, in the antenna device described in Patent Document 1, since one spiral conductor pattern is used for both the HF band and the UHF band, the antenna device acts as a coil antenna in the HF band, and a dipole antenna in the UHF band. It is necessary to optimize the conductor pattern to act as Also, depending on the relationship between the two frequency bands, optimization may not be possible in the first place. That is, since the conductor pattern suitable for the HF band and the conductor pattern suitable for the UHF band are inherently different, if one conductor pattern is used as both the radiation element for the HF band and the radiation element for the UHF band, usually either one of them is used. Characteristics are sacrificed.

  In order to increase the radiation efficiency for the HF band, the size of the radiating element needs to be relatively large. However, if there is a limit to the space for installation, the antenna for the HF band that also serves as the radiating element for the UHF band As the gain will decrease more and more.

  Therefore, an object of the present invention is applicable to two frequency bands, the first frequency band and the second frequency band, and an antenna device having a high gain in any frequency band without increasing its size, and a radio communication including the same To provide an apparatus.

(1) An antenna device according to the present invention is an antenna device that is also used for two frequency bands, a first frequency band and a second frequency band,
A planar conductor having a notch that spans two feed points to which a signal in the second frequency band is fed (between the feed points);
It has a coil conductor wound in a spiral shape or a loop shape so as to have a conductor opening on the inside, and is disposed at a position where the conductor opening of the coil conductor overlaps at least partly with the notch portion in plan view, A feeding coil to which a feeding circuit of the first frequency band is connected;
An additional circuit connected to at least one of the two feeding points of the planar conductor and substantially short-circuited in the first frequency band and substantially short-circuited in the second frequency band;
The planar conductor is electromagnetically coupled to the feeding coil in the first frequency band and acts as a radiation assist element, and acts as a radiation element in the second frequency band.

  According to this configuration, the notch is substantially open in the first frequency band. For this reason, at the time of communication in the first frequency band, the current flowing along the peripheral edge or the notch of the planar conductor does not flow toward the power feeding unit due to the edge effect. Therefore, the planar conductor functions as a so-called booster antenna that expands the radiation range of the magnetic field generated by the feeding coil in the first frequency band. In addition, since the additional circuit is substantially short-circuited in the second frequency band, power feeding from the power feeding circuit in the second frequency band is not hindered by the additional circuit. Therefore, it acts as a radiating element of the dipole antenna in the second frequency band. Thereby, the planar conductor acts as a radiating element of the dipole antenna corresponding to the second frequency band.

  Thus, instead of using the spiral conductor pattern as a radiation element in two frequency bands, the planar conductor functions as a radiation auxiliary element in the first frequency band and functions as a radiation element in the second frequency band. Therefore, the antenna device can be used as a high gain antenna device in any frequency band. Further, since the radiation efficiency is high even in the first frequency band, the overall size does not increase.

(2) For example, the second frequency band is a higher frequency band than the first frequency band, and the additional circuit includes a capacitive element.

(3) The capacitive element may have a capacitance value in which a resonance frequency determined by an inductance of the planar conductor when being fed from the feeding coil is the first frequency band.

  In this configuration, the electromagnetic coupling between the feeding coil and the planar conductor can be strengthened, and the radiation efficiency in the first frequency band can be improved.

(4) For example, the first frequency band is an HF band, and the second frequency band is a UHF band.

  For example, it can be used as an antenna for NFC communication using the HF band and W-LAN (Wireless LAN), GPS or Bluetooth (registered trademark) using the UHF band.

(5) It is preferable that the notch has an opening formed in the planar conductor and a slit extending from an outer edge of the planar conductor to the opening.

  In this configuration, the power feeding coil and the opening can be brought close to each other over, for example, four sides, and the degree of coupling between the power feeding coil and the planar conductor can be increased.

(6) The additional circuit may be a circuit that matches at a plurality of frequencies in the second frequency band.

  With this configuration, communication in a plurality of frequency bands is possible without increasing the number of radiating elements.

  According to the present invention, since the planar conductor functions as a radiation assisting element in the first frequency band and functions as a radiation element in the second frequency band, it can be used as a high-gain antenna device in any frequency band. Further, since the radiation efficiency is high even in the first frequency band, the overall size does not increase. In addition, when using a different frequency in the second frequency band, for example, when using both a UHF GPS and a Bluetooth (registered trademark) antenna, the communication frequency in the second frequency band can be changed by adjusting the power supply unit. Therefore, communication at a different frequency in the second frequency band is possible without changing the shape or the like of the planar conductor.

FIG. 1 is an exploded perspective view of an antenna device 101 according to the first embodiment. FIG. 2 is a circuit diagram of the antenna device 101 in which the UHF band feeding circuit and the additional circuit are represented by equivalent circuits. FIG. 3 is a diagram illustrating an example of a path of current flowing through the coil conductor 21 and the ground conductor 11 of the power feeding coil 2. FIG. 4 is a diagram showing how the ground conductor 11 acts as a radiating element of a dipole antenna. FIG. 5 is a diagram illustrating a first example of an additional circuit in the antenna device of the second embodiment. FIG. 6 is a diagram illustrating a second example of the additional circuit in the antenna device according to the second embodiment. FIG. 7 is a diagram illustrating a first shape of a notch in the antenna device of the third embodiment. FIG. 8 is a diagram showing a second shape of the notch in the antenna device of the third embodiment. FIG. 8 is a diagram showing a third shape of the notch in the antenna device of the third embodiment. FIG. 10 is a circuit diagram of the antenna device 104 according to the fourth embodiment, in which the UHF band feeding circuit and the additional circuit are represented by equivalent circuits. FIG. 11 is a cross-sectional view of a wireless communication apparatus according to the fifth embodiment. FIG. 12 is a cross-sectional view of a wireless communication device 206 according to the sixth embodiment. FIG. 13 is an exploded perspective view showing a state of power feeding to the planar conductor in the wireless communication device 206.

  In the following embodiments, an antenna device according to the present invention and a mobile phone terminal including the antenna device will be described. The antenna device according to each embodiment performs communication in the HF band (first frequency band of the present invention) and the UHF band (second frequency band of the present invention). Communication in the UHF band is, for example, GPS, Bluetooth (registered trademark), W-LAN or the like. Communication in the HF band is, for example, NFC.

<< First Embodiment >>
FIG. 1 is an exploded perspective view of an antenna device 101 according to the first embodiment. FIG. 2 is a circuit diagram of the antenna device 101 in which the UHF band feeding circuit and the additional circuit are represented by equivalent circuits.

  As shown in FIG. 1, the antenna device 101 includes a substrate 9 in which a ground conductor 11 corresponding to a planar conductor of the present invention is formed on a base material 10. The ground conductor 11 has a notch formed by a conductor opening 112 and a slit 111. The slit 111 extends from the outer edge of the ground conductor 11 to the conductor opening 112.

  On the substrate 9, the additional circuit 3 is connected so as to sandwich the slit 111. As will be described in detail later, the additional circuit 3 acts as a simple high-impedance element in the HF band, as a loading capacitor, or as a resonance capacitor, and in the UHF band as a connection path to the UHF band feeding circuit or in the UHF band. Acts as a matching circuit.

  In addition, the antenna device 101 includes a power feeding coil 2 in which a coil conductor 21 wound in a spiral shape or a loop shape so as to have a coil opening portion CW is formed on a flexible base material 22. This feeding coil is arranged at a position where the coil opening CW overlaps at least partially with the notch (particularly the conductor opening 112) in plan view. A connecting portion 2A for connecting an HF band feeding circuit to the coil conductor 21 of the feeding coil 2 is provided. The connector 2A may be provided with a connector for connecting to the power feeding circuit.

  As shown in FIG. 2, the additional circuit 3 is electrically connected to the ground conductor 11 at two points (hereinafter referred to as a UHF band feeding point) sandwiching the slit 111. In this example, the additional circuit 3 is a capacitor C1. The UHF band feeding circuit 4 feeds power to the UHF band feeding point via the capacitor C1.

  Here, the operation of the antenna device 101 shown in FIGS. 1 and 2 as an HF band antenna will be described. FIG. 3 is a diagram illustrating an example of a path of current flowing through the coil conductor 21 and the ground conductor 11 of the power feeding coil 2. The broken line arrows in FIG. 3 indicate the direction of current flowing through the coil conductor 21. However, the coil conductor 21 is simplified in FIG.

  In the HF band, the impedance of the capacitor C1, which is the additional circuit 3, is sufficiently high, and it can be considered that the slit 111 is equivalently opened in the HF band.

  Since the coil opening CW of the coil conductor 21 overlaps the conductor opening 112 in plan view, the coil conductor 21 is electromagnetically coupled to the conductor opening 112 of the ground conductor 11. Therefore, a current is induced in the conductor opening 112 of the ground conductor 11 in a direction (solid arrow) opposite to the direction of the current flowing through the coil conductor 21 of the power feeding coil 2 (broken arrow). The current that flows along the edge of the conductor opening 112 flows along the outer periphery of the ground conductor 11 through the edge of the slit 111 due to the edge effect. In plan view, the current flowing along the periphery of the ground conductor 11 is in the same direction as the current flowing in the coil conductor 21. For this reason, a magnetic field in the same direction as the magnetic field generated from the coil conductor 21 is generated from the ground conductor 11. The ground conductor 11 has a larger area than the coil conductor 21, and a current flowing through the ground conductor 11 generates a magnetic field that spreads over a wide range, thereby extending the communication distance.

  In particular, when the conductor opening 112 and the coil opening CW have substantially the same size in plan view and are brought close to the coil conductor 21 on the four sides of the conductor opening 112, the coil conductor 21 is seen in the conductor opening 112 in plan view. Therefore, the electromagnetic field coupling between the edge of the conductor opening 112 of the ground conductor 11 and the coil conductor 21 is increased. Therefore, a larger current flows through the ground conductor 11, and the ground conductor 11 can efficiently radiate the magnetic field generated by the feeding coil 2.

  Note that the capacitor C1 of the additional circuit 3 may constitute a resonance circuit together with the ground conductor 11 (radiation auxiliary element). In other words, an LC resonance circuit whose resonance frequency is an operating frequency in the HF band may be configured by the inductance of the ground conductor 11 and the capacitance of the capacitor C1 as a radiation auxiliary element. This resonant operation will be shown in another embodiment later.

  Next, the operation of the antenna device 101 shown in FIGS. 1 and 2 as a UHF band antenna will be described. FIG. 4 is a diagram showing how the ground conductor 11 acts as a radiating element of a dipole antenna. The length L of the ground conductor 11 shown in FIG. 4 is the length of one side of the substrate 9 shown in FIG. 1 (dimension in the direction across the slit 111) L, and the use frequency in the UHF band is represented by λ. For example, L = λ / 2. The UHF band power supply circuit 4 includes a power supply unit 41 and a balun transformer 42. The balun transformer 42 converts the unbalanced current I ′ from the power feeding unit 41 into a pair of balanced currents I and −I. These balanced currents I and -I are respectively fed to the feeding point of the ground conductor 11 via the additional circuit 3. Here, since the capacitor C1 has a low impedance in the UHF band, power is supplied in the same manner as when the balun transformer 42 is directly connected. As a result, balanced currents I and -I having equal amplitude and opposite phase flow through the ground conductor 11, so that the current I flows from one end to the other end of the ground conductor 11, and the ground conductor 11 serves as a radiating element of the dipole antenna. Works.

  The capacitor C1 of the additional circuit 3 may be used as a matching element between the balun transformer 42 and the ground conductor 11 (radiating element).

  As described above, the planar conductor is electromagnetically coupled with the feeding coil 2 in the HF band and acts as a radiation assist element (booster antenna) in the HF band, and acts as a direct radiation element in the UHF band in the UHF band. To do. Therefore, the antenna device 101 can be used as an antenna for the HF band by feeding by the feeding coil 2 and can be used as an antenna for the UHF band by feeding by the feeding circuit 4 for the UHF band. For this reason, a wireless communication device such as a mobile phone terminal in which the antenna device 101 is mounted does not require radiating elements corresponding to HF band communication and UHF band communication, and space saving and cost reduction can be realized.

<< Second Embodiment >>
The second embodiment shows two examples in which the configuration of the additional circuit is different from that of the first embodiment.

  In the antenna device 102A shown in FIG. 5, the additional circuit 3A further includes a capacitor C2 in addition to the capacitor C1. The additional circuit 3A is connected to the first point of the feeding point of the ground conductor 11 via the capacitor C1, and is connected to the second point of the feeding point of the ground conductor 11 via the capacitor C2. In the first embodiment, in the HF band communication, one feeding point of the ground conductor 11 and the additional circuit 3 are substantially cut off. However, in the example of FIG. The point can be substantially cut off from the additional circuit 3A. For this reason, it is less likely to be affected by the additional circuit 3A and the UHF band feeding circuit 4 when used as an HF band antenna.

  In the antenna device 102B shown in FIG. 6, the additional circuit 3B includes capacitors C3, C4, C5 and two inductors L1, L2. The inductor L1 is connected to the UHF band power supply circuit 4, and the inductor L2 is connected to the capacitors C4 and C5, respectively. The inductors L1 and L2 constitute a transformer. The capacitor C4 is connected to the first point of the feeding point of the ground conductor 11, and the capacitor C5 is connected to the second point of the feeding point of the ground conductor 11. Capacitor C3 is connected in parallel to capacitors C4 and C5 and inductor L2. Capacitors C4 and C5 have high impedance in the HF band and low impedance in the UHF band, similarly to capacitors C1 and C2 in FIG. The capacitor C3 forms an LC resonance circuit with the inductor L2, and functions as a matching circuit in the UHF band.

<< Third Embodiment >>
In the third embodiment, another example of the cutout portion of the ground conductor 11 is shown.

  In the antenna device 103 </ b> A shown in FIG. 7, the ground conductor 11 </ b> A has a rectangular notch 113 formed at the end of the slit 111 opposite to the conductor opening 112 in addition to the slit 111 and the conductor opening 112. Yes. Thereby, it becomes easy to mount the circuit element on the portion where the notch 113 is formed. In the ground conductor 11A, two points sandwiching the notch 113 are UHF band feeding points, and the additional circuit 3 and the UHF band feeding circuit 4 are connected to the feeding point. Thus, for example, when the additional circuit 3 is connected to the feeding point of the ground conductor 11A, the notch 113 may be formed to facilitate the connection of the additional circuit 3 to the feeding point of the ground conductor 11A. . Further, since the length of the radiating element of the ground conductor 11A that acts as a radiating element of the dipole antenna varies depending on the width of the notch 113, the radiating element length of the dipole antenna is appropriately determined by determining the width of the notch 113. May be.

  In the antenna device 103B shown in FIG. 8, the ground conductor 11B includes a ground conductor formation region in which the ground conductor 11B extends in a planar shape and other non-ground regions, and has a line shape parallel to the non-ground region from the ground conductor formation region. Conductive patterns 115 and 116 are formed to extend. A non-ground region surrounded by the ground conductor 11B and the conductor patterns 115 and 116 is a notch.

  The feeding coil 2 is arranged such that the coil opening CW overlaps at least a part of the conductor patterns 115 and 116 and the ground conductor 11B and the notch in a plan view. Further, the end portions of the conductor patterns 115 and 116 are used as feeding points, and the additional circuit 3 and the UHF band feeding circuit 4 are connected to the feeding points.

  In the antenna device 103 </ b> C shown in FIG. 9, the ground conductor 11 </ b> C has a rectangular notch at one rectangular corner. The feeding coil 2 is arranged so that the coil opening CW partially or entirely overlaps with the notched portion of the ground conductor 11C in plan view. Further, two points sandwiching the rectangular cutout portion as diagonals are set as feeding points, and the additional circuit 3 and the UHF band feeding circuit 4 are connected to the feeding points.

  As described above, the notches formed in the ground conductors (11A, 11B, 11C) can take various shapes. Further, when the ground conductor acts as a radiating element of the dipole antenna, the substantial radiating element length of the dipole antenna can be adjusted according to the shape of the notch. Further, the shape of the ground conductor can be appropriately changed according to the arrangement of the circuit elements mounted on the base material 10.

<< Fourth Embodiment >>
In the fourth embodiment, an antenna device applied to a communication system using two frequencies in the UHF band and a communication system using the HF band is shown.

  FIG. 10 is a circuit diagram of the antenna device 104 according to the fourth embodiment, in which the UHF band feeding circuit and the additional circuit are represented by equivalent circuits.

  As in the first embodiment, the antenna device 104 includes a ground conductor 11, a feeding coil 2, a connecting portion 2A for connecting a feeding circuit to the feeding coil 2, an HF band feeding circuit 25, and the like. Further, the antenna device 104 includes an additional circuit 3C connected to the feeding point of the ground conductor 11 and UHF band feeding circuits 4A and 4B. The additional circuit 3C includes a capacitor C1 and a switch element SW that connects the capacitor C1 to one of the UHF band power supply circuits 4A and 4B.

  For example, the power feeding circuit 4A is a GPS signal receiving circuit, and the power feeding circuit 4B is a Bluetooth (registered trademark) transmission / reception circuit. The feeding points of the feeding circuits 4A and 4B are different. In this example, when the switch element SW of the additional circuit 3C is connected to the power supply circuit 4A side, the ground conductor 11 resonates with the inductance generated particularly in the notch and the capacitance of the capacitor C1, and the ground conductor 11 is for GPS. Acts as a radiating element. On the other hand, when the switch element SW of the additional circuit 3C is connected to the power feeding circuit 4B side, resonance occurs due to the inductance generated in the notch portion of the ground conductor 11 and the capacitance of the capacitor C1, and the ground conductor 11 is Bluetooth (registered trademark). It acts as a radiating element.

  The operation of the ground conductor 11 as a booster antenna in the HF band is the same as that of the embodiments shown so far.

  As described above, the additional circuit 3C is a circuit that matches at a plurality of frequencies in the UHF band, for example, a circuit that resonates at a frequency of λ / 4 and 3λ / 4, thereby allowing communication at different frequencies even in the same UHF band. Even if the types of communication increase, there is no need to provide an antenna device for each communication. A matching capacitor or the like may be further provided at least between the power feeding circuits 4A and 4B and the switch element SW.

  In the antenna device disclosed in Patent Document 1, for example, when changing the frequency in the UHF band, it is necessary to change the shape (size) of the coil antenna, and it is difficult to change the communication frequency. Although there is a problem that it is difficult to establish a plurality of resonances, the configuration as in this embodiment of the present invention can be applied to a communication system using a plurality of frequencies in the second frequency band (UHF band).

<< Fifth Embodiment >>
FIG. 11 is a cross-sectional view of a wireless communication apparatus according to the fifth embodiment.

  A substrate 9 is accommodated in the housing 30 of the wireless communication device 205. Ground conductors 11 and 12 and other wiring patterns are formed on the base material 10 of the substrate 9. A plurality of electronic components 10A are mounted.

  In this example, the ground conductors 11 and 12 are formed on both surfaces of the base material 10, and the conductor opening 112 and the slit 111 as shown in FIG. 1 in the first embodiment are formed on the upper surface of the ground conductor 11. Is formed. The ground conductor 12 is formed with a conductor opening 122 and a slit having the same pattern as the conductor opening 112 and the slit 111 of the ground conductor. Such a ground conductor may be formed in the inner layer of the substrate 10. The ground conductors 11 and 12 may be formed on a part of the plane of the base material 10.

  On the upper surface of the substrate 9, a feeding coil 2 for HF band is provided. The configuration of the feeding coil 2 is the same as that shown in FIG. 1 in the first embodiment. The power supply coil 2 is affixed on the substrate 9 by, for example, a double-sided pressure-sensitive adhesive sheet 2B (or adhesive). The feeding coil 2 is connected to, for example, an HF band RFIC, which is a HF band feeding circuit mounted on the substrate 9, via a connector serving as a connection portion 2A. The HF band RFIC circuit includes a power supply unit that supplies power to the power supply coil 2 and a capacitor (not shown) connected in parallel to the power supply coil 2. The resonance frequency is determined by the inductance determined by the coil conductor 21 of the feeding coil 2 and the capacitance of the capacitor. For example, when the HF band having a center frequency of 13.56 MHz is used in NFC communication, the resonance frequency is set to 13.56 MHz.

  The capacitor C1 shown in FIG. 2 and the like is designed to have a high impedance or a low impedance depending on the frequency band, but has a capacitance value that resonates with the inductance formed by the ground conductor 11 during HF band communication. It may be designed. Specifically, the capacitance of the capacitor C1 is designed to resonate with the inductance of the ground conductor 11 when flowing along the notch and the outer peripheral edge of the ground conductor 11 at the communication frequency in the HF band. To do.

  Here, when the capacitance of the capacitor C1 is represented by C, the inductance of the ground conductor 11 in the HF band (that is, when current flows along the edge of the ground conductor 11) is represented by L, and the communication frequency f1 in the HF band. , F1 = 1 / (2π√ (LC)). Since the capacitor C1 and the ground conductor 11 resonate in this manner, the electromagnetic coupling between the feeding coil 2 and the ground conductor 11 can be further strengthened, and the radiation efficiency of the magnetic field by the ground conductor 11 can be increased. As a result, a communication distance in HF band communication can be secured even when a relatively small ground conductor is used.

<< Sixth Embodiment >>
FIG. 12 is a cross-sectional view of a wireless communication device 206 according to the sixth embodiment. FIG. 13 is an exploded perspective view schematically showing a state of power feeding to the planar conductor.

  In the first to fifth embodiments, the ground conductor 11 of the substrate 9 is caused to act as a radiating element for the booster antenna and the dipole antenna. However, in the sixth embodiment, the metal plate 13 which is a separately provided planar conductor is used as the booster. It acts as a radiating element for the antenna and dipole antenna.

  The substrate 9 includes the additional circuit 3 and the HF band power supply circuit 25 similar to those shown in the first embodiment. A plurality of electronic components 10A, a camera module 10B, and the like are mounted.

  The metal plate 13 may be provided along a housing of a wireless communication device such as a mobile phone terminal, or may be a metal plate of the housing. In the example shown in FIG. 12, the metal plate 13 disposed along the housing 30 is caused to act as a radiating element of an HF band booster antenna and a UHF band dipole antenna.

  The metal plate 13 is disposed along the back surface (or front surface) of the housing 30 of the wireless communication device such as a mobile phone terminal, and faces the substrate 9. In order to arrange the metal plate 13 along the casing 30, a part thereof may be bent as shown in FIG. The metal plate 13 is formed with a slit 131 along the longitudinal direction from one end in the longitudinal direction of the housing and a rectangular opening 132 communicating with the outer edge via the slit 131.

  The metal plate 13 is provided with the feeding coil 2 so that the opening 132 and the coil opening CW overlap when viewed in plan. In the present embodiment, the feeding coil 2 further includes a magnetic sheet 23, and the magnetic sheet 23 is laminated on the flexible base material 22 so as to be on the substrate 9 side. The magnetic sheet 23 is, for example, ferrite formed into a sheet shape. The magnetic sheet 23 acts as a magnetic shield for preventing the magnetic field generated from the power feeding coil 2 from reaching other electronic components 10A and the like included in the mobile phone terminal device and so on.

  The connecting portion of the coil conductor 21 of the power feeding coil 2 is electrically connected to the HF band power feeding circuit 25 of the substrate 9 by contact pins 141 and 142. Further, the metal plate 13 has two points sandwiching the slit 131 as feed points, and the feed points are connected to the additional circuit 3 and the UHF band feed circuit 4 by contact pins 151 and 152.

  In addition, when the metal plate 13 or the like is an obstacle to the installation of the element mounted on the substrate 9, for example, the camera module 10 </ b> B, the element such as the camera module 10 </ b> B or the like The structure inserted in the part CW may be sufficient.

C1-C5: Capacitor CW ... Coil opening L1, L2 ... Inductor SW ... Switch element 2 ... Feed coil 2A ... Connection part 2B ... Double-sided adhesive sheet 3, 3A, 3B, 3C ... Additional circuit 4, 4A, 4B ... UHF band Power feeding circuit 9 ... Substrate 10 ... Base material 10A ... Electronic component 10B ... Camera modules 11, 12 ... Ground conductors 11A, 11B, 11C ... Ground conductor 13 ... Metal plate 21 ... Coil conductor 22 ... Flexible base material 23 ... Magnetic material sheet 25 ... HF band feeding circuit 30 ... Case 41 ... Feeding section 42 ... Balance transformer 101 ... Antenna devices 102A, 102B ... Antenna devices 103A, 103B, 103C ... Antenna device 104 ... Antenna device 111 ... Slits 112, 122 ... Conductor openings Part 115, 116 ... Conductor pattern 131 ... Slit 132 ... Opening part 141, 142 ... Contact Pin 151, 152 ... contact pins 205, 206 ... wireless communication device

Claims (7)

An antenna device that is also used for two frequency bands, a first frequency band and a second frequency band,
A planar conductor having a notch spanning two feeding points to which a signal in the second frequency band is fed;
A coil conductor wound in a spiral shape or a loop shape so that the inside becomes a coil opening portion, and the coil opening portion is disposed at a position overlapping at least partly with the notch portion in plan view; A power supply coil to which a power supply circuit in a frequency band is connected;
An additional circuit connected to at least one of the two feeding points of the planar conductor and substantially short-circuited in the first frequency band and substantially short-circuited in the second frequency band;
The planar conductor is electromagnetically coupled to the feeding coil in the first frequency band and acts as a radiation assist element, and acts as a radiation element in the second frequency band. The second frequency band is a higher frequency band than the first frequency band;
The antenna device according to claim 1, wherein the additional circuit includes a capacitive element.   The antenna device according to claim 2, wherein the capacitive element has a capacitance value in which a resonance frequency determined by an inductance of the planar conductor when being fed from the feeding coil is the first frequency band.   The antenna device according to claim 2 or 3, wherein the first frequency band is an HF band, and the second frequency band is a UHF band.   5. The antenna device according to claim 1, wherein the notch has an opening formed in the planar conductor and a slit extending from an outer edge of the planar conductor to the opening.   The antenna device according to claim 1, wherein the additional circuit is a circuit that matches at a plurality of frequencies in the second frequency band. In a radio communication apparatus provided with an antenna device that is also used in two frequency bands, a first frequency band and a second frequency band, and a power feeding circuit that feeds power to the antenna apparatus,
The antenna device is
A planar conductor having a notch spanning two feeding points to which a signal in the second frequency band is fed;
A coil conductor wound in a spiral shape or a loop shape so that the inside becomes a coil opening portion, and the coil opening portion is disposed at a position overlapping at least partly with the notch portion in plan view; A power supply coil to which a power supply circuit in a frequency band is connected;
An additional circuit connected to at least one of the two feeding points of the planar conductor and substantially short-circuited in the first frequency band and substantially short-circuited in the second frequency band;
The planar conductor is electromagnetically coupled to the feeding coil in the first frequency band and acts as a radiation assist element, and acts as a radiation element in the second frequency band.

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