JP2010226509A - Antenna device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multi-resonant antenna device, wherein a low-frequency antenna is downsized while maintaining the radiation efficiency of a high-frequency antenna. <P>SOLUTION: In the antenna device, an antenna element 10 includes a substantially rectangular parallelepiped substrate 11 comprising a dielectric substance and two radiating conductors (first radiating conductor 12 and second radiating conductor 13) which resonate at two types of resonance frequencies are arranged on the top of the substrate 11. A cavity 17 is arranged in the substrate 11. If the height of a first cavity 17a which is positioned under the first radiating conductor 12 is denoted by h<SB>1</SB>and the height of a second cavity 17b which is positioned under the second radiating conductor 13 is denoted by h<SB>2</SB>, then h<SB>1</SB><h<SB>2</SB>. Ends of one side of the first and second radiating conductors 12 and 13 are open ends. Both of the open ends are aligned on the ridge line of the end of the substrate 11 in the length direction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an antenna device, and more particularly to a structure of a multi-resonant antenna having a plurality of antenna resonance points.

  A multi-resonant antenna has attracted attention as one of surface-mounted antennas incorporated in wireless communication devices such as mobile phones (see, for example, Patent Document 1). A multi-resonant antenna is configured such that a plurality of radiating conductors are formed on a dielectric substrate, the feeding points of the radiating conductors are common, and the resonance frequencies are different. For example, one of the two radiating conductors is used for GPS. The antenna and the other can be used as a wireless LAN antenna. It is also possible to increase the resonance frequency bandwidth by slightly shifting the two resonance frequencies so that part of the frequency bands overlap.

  Patent Document 2 discloses an L-shaped substrate made of a dielectric, an inverted F antenna made up of a first radiation electrode, a first connection electrode, and a feeding electrode, and a second radiation electrode and a second connection. A microstrip antenna comprising electrodes is formed, the open end of the second radiating electrode of the microstrip antenna is brought close to the feeding electrode of the inverted F antenna, and a line connecting the open end of the first and second radiating electrodes and the ground end There is disclosed an antenna device that is arranged so as to intersect at approximately 90 degrees. According to this antenna device, the maximum area of the antenna becomes very large, but the radiation efficiency of the two antennas can be maintained.

  Patent Document 3 discloses an antenna structure in which a dielectric substrate is provided with a low-side feeding radiation electrode and a high-side feeding radiation electrode. In this antenna structure, in the low-side power supply radiation electrode, the power supply unit is connected to the wireless communication circuit directly or via a capacitance unit. At least one electrode edge portion on both sides of the power supply unit is grounded to the ground electrode via a reactance circuit having an inductance unit. In the high-side power supply radiation electrode, the power supply unit is connected to the wireless communication circuit via the inductance unit. In addition, at least one electrode edge portion on both sides of the power feeding unit is directly grounded to the ground electrode by the short electrode. According to this antenna structure, it is possible to easily cope with wireless communication in a plurality of frequency bands and to obtain satisfactory antenna matching conditions.

Japanese Patent No. 4044302 JP 11-31923 A Japanese Patent Laid-Open No. 2008-205991

  In general, the length of the radiation conductor constituting the antenna element is determined by the resonance wavelength. The lower the resonance wavelength, the longer the length of the radiation conductor, but when the wavelength shortening effect is enhanced by using a high dielectric constant substrate The length of the radiation conductor can be shortened. Therefore, also in the multi-resonance antenna, the length of the radiation conductor of the low-frequency side antenna can be shortened by increasing the dielectric constant of the base, and thereby the overall size of the multi-resonance antenna can be reduced.

  However, the multi-resonant antenna is formed by forming a low-frequency antenna operating at a relatively low resonance frequency and a high-frequency antenna operating at a higher resonance frequency on a common substrate. Since not only the low-frequency side antenna but also the high-frequency side antenna is formed on the upper side, there is a problem that the radiation conductor of the high-frequency side antenna becomes extremely small when a high dielectric constant substrate is simply used. Therefore, there is a problem that the radiation efficiency of the high frequency side antenna is greatly reduced.

  According to the conventional antenna device described in Patent Document 2, the radiation efficiency of the two antennas can be maintained, but there is a problem that the maximum area of the antenna becomes very large. Further, according to the conventional antenna structure described in Patent Document 3, it is possible to cope with wireless communication in a plurality of frequency bands, but the low-side radiation electrode provided on the edge side of the substrate is provided on the inner side of the substrate. Further, there is a possibility that the radiation of the high-side radiation electrode is inhibited and the radiation efficiency of the high-side radiation electrode is lowered.

  The present invention solves the above problems, and an object of the present invention is to provide a multi-resonance antenna capable of reducing the size of the low-frequency antenna while maintaining good radiation efficiency of the high-frequency antenna. To provide an apparatus.

In order to solve the above problems, an antenna device according to the present invention includes an antenna element and a printed circuit board on which the antenna element is mounted. The antenna element is formed on a base made of a substantially rectangular parallelepiped dielectric, on at least the upper surface of the base. A first radiation conductor that resonates at the formed first resonance frequency, and a second radiation that resonates at a second resonance frequency that is higher than the first resonance frequency formed on at least the upper surface of the substrate together with the first radiation conductor. And a base body is provided below the first radiation conductor, and is provided below the first radiation portion having a _first height h1 from the bottom surface of the base body and below the second radiation conductor. And a second cavity having a _second height h ₂ higher than the first height h ₁ from the bottom surface of the substrate, and the first and second radiation conductors are parallel to each other in a strip pattern And provided along the longitudinal direction of the substrate. One end of each of the first and second radiation conductors is connected to a power supply line provided on the printed circuit board, and the other end of each of the first and second radiation conductors is an open end. It is characterized by terminating at the ridge line position.

  According to the present invention, the base body includes the first cavity portion and the second cavity portion, the antenna element ANT1 having a lower resonance frequency is formed above the first cavity portion, and the second cavity portion Since the antenna element ANT2 on the higher resonance frequency side is formed above, the antenna element ANT2 on the higher resonance frequency side becomes too small, and the problem that the radiation characteristic is greatly deteriorated can be solved. That is, it is possible to realize a multi-resonant antenna that is small and has excellent radiation characteristics.

  The antenna mounting area where the antenna element is mounted is provided in contact with the edge of the printed circuit board, the first radiating conductor is located on the side close to the edge of the printed circuit board, and the second radiating conductor is the edge of the printed circuit board. It is preferable to be located on the side far from the center. According to this configuration, since the hollow portion is provided in the lower portion of the base body, the path of the radio wave radiated from the second radiation conductor is not easily obstructed by the base body. Therefore, the radiation efficiency of the second radiation conductor far from the edge can be improved.

In the present invention, the base of the antenna element has first and second legs provided at both ends of the base in the longitudinal direction, and is located on the open end side of the first and second radiation conductors. It is preferable that the width S1 of the _first leg is λg / 20 or more (λg is an effective wavelength of the second resonance frequency). The electric field concentrates at a position of approximately λg / 20 from the tips of the first and second radiation conductors, but if the width of the first foot is λg / 20 or more, the tips of the first and second radiation conductors The dielectric can be left to some extent immediately below the part, and a capacitance can be provided between the terminal electrode connected to the ground and the radiation conductor, so that the antenna element can be downsized.

In the present invention, the base of the antenna element has first and second legs provided at both ends in the longitudinal direction of the base, and is located on the feeding side of the first and second radiation conductors. It is preferable that the width S _{2 of the second} leg is not less than the first height h _{1 and not} more than the second height h ₂ . If the thickness of the dielectric changes drastically when the first and second radiating conductors are bent at right angles from the side surface to the upper surface of the substrate, current reflection occurs at the bent position, and the antenna characteristics deteriorate. there is a possibility. However, if the width S ₂ of the second leg is in the range of h _{1 to} h ₂ , good antenna characteristics can be obtained.

  According to the present invention, it is possible to reduce the size of the antenna element that operates on the low resonance frequency side while maintaining the radiation efficiency of the antenna element that operates on the high resonance frequency side. It is possible to provide a multi-resonance antenna device that has been realized.

1 is a schematic perspective view showing a structure of an antenna device 100 according to a first embodiment of the present invention. FIG. 2 is a schematic development view of the antenna element 10 shown in FIG. 1. FIG. 3 is a schematic cross-sectional view of the antenna element 10 along the line AA ′ in FIG. 2. (A) is the layout of the front surface of the printed circuit board 20, and (b) is the layout of the back surface of the printed circuit board 20. It is a schematic diagram showing a radiation path of radio waves from the first and second radiation conductors 12 and 13.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic perspective view showing the structure of an antenna device 100 according to a first embodiment of the present invention. FIG. 2 is a schematic development view of the antenna element 10 shown in FIG.

  As shown in FIG. 1, the antenna device 100 according to the present embodiment includes an antenna element 10 and a printed board 20 on which the antenna element 10 is mounted. The antenna element 10 is one main surface (front surface) of the printed board 20. It is mounted in the antenna mounting area provided in

  As shown in FIGS. 1 and 2, the antenna element 10 is a multi-resonant antenna, and includes a base body 11 made of a dielectric and a plurality of conductor patterns formed on the base body 11. The base body 11 has a substantially rectangular parallelepiped shape in which the Y direction is the longitudinal direction, the X direction is the width direction, and the Z direction is the height direction. Among these, the upper surface 11a, the bottom surface 11b, and the two side surfaces 11c and 11d of the base body 11 are surfaces parallel to the Y direction, the side surfaces 11e and 11f are surfaces orthogonal to the Y direction, and the bottom surface 11b is mounted on the printed circuit board 20. Surface. The vertical direction of the antenna element 10 is defined with the surface of the printed circuit board 20 as a reference plane.

  Although it does not specifically limit as a material of the base | substrate 11, Ba-Nd-Ti type material (relative dielectric constant 80-120), Nd-Al-Ca-Ti type material (relative dielectric constant 43-46), Li—Al—Sr—Ti (relative permittivity 38 to 41), Ba—Ti based material (relative permittivity 34 to 36), Ba—Mg—W based material (relative permittivity 20 to 22), Mg—Ca— Ti-based materials (relative permittivity 19 to 21), sapphire (relative permittivity 9 to 10), alumina ceramics (relative permittivity 9 to 10), cordierite ceramics (relative permittivity 4 to 6), and the like can be used. . The substrate 11 is produced by firing these material powders using a mold.

What is necessary is just to select a dielectric material suitably according to the target frequency. As the relative permittivity ε _r increases, a greater wavelength shortening effect can be obtained, so that the length of the radiation conductor can be shortened, but the radiation efficiency decreases, so the relative permittivity ε _r does not necessarily have to be large. There is an appropriate value. Therefore, for example, when the target frequency is 2.4 GHz, it is preferable to use a material having a relative dielectric constant ε _r of about 5 to 40. According to this, it is possible to reduce the size of the substrate while ensuring sufficient radiation efficiency. Preferred examples of the material having a relative dielectric constant ε _r of about 5 to 40 include Mg—Ca—Ti dielectric ceramics. As the Mg—Ca—Ti dielectric ceramic, it is particularly preferable to use a Mg—Ca—Ti dielectric ceramic containing TiO ₂ , MgO, CaO, MnO, and SiO ₂ .

  As shown in FIG. 2, the conductor pattern of the antenna element 10 includes first and second radiation conductors 12 and 13 formed from the side surface 11e to the upper surface 11a of the base body 11, and terminals formed on the bottom surface 11b of the base body 11. Electrodes 14-16 are provided. These conductor patterns can be formed by applying an electrode paste material by a method such as screen printing or transfer and then baking under a predetermined temperature condition. Silver, silver-palladium, silver-platinum, copper, or the like can be used as the electrode paste material. In addition to this, the conductor pattern can also be formed by plating or sputtering.

  FIG. 3 is a schematic cross-sectional view of the antenna element 10 taken along the line AA ′ of FIG.

As shown in FIGS. 1 to 3, the schematic shape of the base 11 is a rectangular parallelepiped, but is not a complete rectangular parallelepiped, and the bottom of the center in the longitudinal direction of the base 11 is removed and penetrates in the width direction of the base 11. The cavity portion 17 is provided. Although details will be described later, the cavity 11 has a stepped shape, and the height of the cavity 11 changes stepwise. That is, the cavity 11 is provided below the first radiation conductor 12, and below the first cavity 17 a having the first height h ₁ from the bottom surface of the base 11 and the second radiation conductor 13. provided, and a second cavity portion 17b having a second height h ₂ greater than the height h ₁ from the bottom first substrate 11. For example, when the size of the base 11 is 12 × 3 × 3 mm, the height h ₁ of the first cavity 17 is set to 0.3 mm, and the height h ₂ of the second cavity 18 is set to 1.6 mm. can do.

First radiating conductor 12, which functions as the first antenna element ANT1 that resonates at first resonant frequency _{f 1,} while in contact with the long side 11h of the vertical side 11g and the upper surface 11a of the side surface 11e of the base 11 It is the elongate strip | belt-shaped conductor pattern formed continuously. The second radiation conductor 13 functions as a second antenna element ANT2 that resonates at a _second resonance frequency f ₂ (f ₂ > f ₁ ) that is higher than the first resonance frequency f _1. This is an elongated strip-like conductor pattern continuously formed in contact with the vertical side 11i of the side surface 11e and the long side 11j of the upper surface 11a. One end of each of the first and second radiating conductors 12 and 13 is connected to the terminal electrode 15, and the other end extends to the short side 11 k of the upper surface 11 a of the base 11 and becomes an open end. Although not particularly limited, when the width of the base 11 is 3 mm, the width of the first and second radiation conductors 12 and 13 can be set to 0.8 mm.

Since the resonance frequency f ₁ of the first antenna element ANT ₁ is lower than the resonance frequency f ₂ of the first antenna element ANT ₂ , the length of the first radiation conductor 12 is usually longer than that of the second radiation conductor 13. However, in this embodiment, the lengths of the first radiating conductor 12 and the second radiating conductor 13 are the same. That is, the open ends of the first and second radiation conductors 12 and 13 are aligned with the ridge line (short side 11k) at one end in the longitudinal direction of the base 11. This is due to the fact that the cavity portion 17 whose height changes stepwise is formed at the bottom of the base body 11, and the wavelength shortening effect of the base body 11 with respect to the first and second radiation conductors 12 and 13 is thereby different. .

  In order to increase the resonance frequency of the antenna element, it is only necessary to lengthen the radiation conductor, and in order to decrease the resonance frequency, it is only necessary to shorten the radiation conductor. Therefore, the length of the radiation conductor is made shorter than the length of the substrate. Conversely, it is also possible to extend to the side surface 11f of the base 11. That is, it can be considered that the lengths of the first and second radiation conductors 12 and 13 are not uniform. However, when the tips are uneven, not only the surface area of the base 11 cannot be used effectively, but also the positions where the electric field concentrates at the tips of the radiation conductors are different from each other, so that the antenna characteristics can be very adjusted. It becomes difficult. However, according to the present embodiment, since the open ends of the first and second radiation conductors 12 and 13 are aligned with the ridge line at one end in the longitudinal direction of the base 11, the surface area of the base 11 is utilized to the maximum. Therefore, the antenna design can be facilitated.

  The terminal electrodes 14 and 15 are formed on one end side in the longitudinal direction of the bottom surface 11b of the base 11, and the third terminal electrode 16 is formed on the other end side. One end of each of the first and second radiation conductors 12 and 13 is connected to the second terminal electrode 15. The terminal electrodes 14 and 15 are strip-like patterns extending in the width direction of the base 11, and both face each other with a gap g having a predetermined width, and capacitive coupling occurs between them. When the antenna element 10 is mounted on the printed circuit board 20, the terminal electrode 14 is connected to a feed line on the printed circuit board 20.

As shown in FIG. 2, the cavity 17 is formed at the bottom in the longitudinal center of the base 11, so that the legs 18 a and 18 b are formed at both ends in the longitudinal direction of the base 11. The foot portions 18 a and 18 b are portions having a bottom surface that comes into contact with the printed circuit board 20. Here, when the effective wavelength of the resonance frequency on the high frequency side is λg, the width S ₁ of the first foot 18a located on the open end side is preferably λg / 20 or more. This is because the electric field concentrates at a position of approximately λg / 20 from the tips of the first and second radiating conductors 12 and 13, so that if the width of the first leg 18 a is λg / 20 or more, Since the dielectric can be left to some extent directly under the tips of the second radiation conductors 12 and 13, and a capacitance can be provided between the terminal electrode 16 connected to the ground and the radiation conductors 12 and 13, This is because the antenna element can be downsized.

On the other hand, the width _{S 2} of the second leg portion 18b on the opposite of the feed side to the open end side is preferably at _{h 1} more _{h 2 below, S 2 = (h 1 + h} 2) / 2 It is particularly preferred. This is because if the thickness of the dielectric changes drastically when the first and second radiating conductors 12 and 13 are bent at a right angle from the side surface 11e to the upper surface 11a of the base 11, current reflection occurs at the bent position. This is because the antenna characteristics deteriorate. However, the width S ₂ of the foot portion 18b is as long as h ₁ to h _2, not the antenna characteristics are deteriorated, it is possible to obtain good antenna characteristics.

  4A and 4B are schematic plan views showing a pattern layout on the printed circuit board 20 on which the antenna element 10 is mounted. FIG. 4A is a layout of the front surface 20a of the printed circuit board 20, and FIG. 4B is a layout of the back surface 20b of the printed circuit board. It is. In particular, (b) shows the layout of the back surface 20b transparently from the front surface 20a side.

  As shown in FIG. 4, the printed circuit board 20 has a conductive pattern formed on the front and back surfaces of the insulating substrate 21. In particular, one side of the printed circuit board 20 has a longitudinal direction (Y The antenna mounting area 23 is provided in a substantially rectangular shape in contact with the edge 20 e in the direction and having the other three sides defined by the ground pattern 22. The antenna mounting area 23 is, in principle, a rectangular insulating area from which the ground pattern 22 is excluded, but three lands 24 to 26 are provided in the antenna mounting area 23. Since the lands 25 and 26 are connected to the surrounding ground pattern 22, strictly speaking, it is not an area where the ground pattern 22 is excluded. As shown in the figure, when the antenna mounting area 23 is provided at the corner portion of the printed circuit board 20, the two directions are free spaces where the printed circuit board (ground pattern) does not exist as viewed from the antenna element. Efficiency can be increased.

  The lands 24 to 26 are connected to the terminal electrodes 14 to 16 of the antenna element 10, respectively. The land 24 is connected to the power supply line 27, and the lands 25 and 26 are connected to the adjacent ground pattern 22. A floating land 29 is provided in the antenna mounting area 23, and a lead portion 29 a of the floating land 29 is connected to the adjacent ground pattern 22 via a frequency adjusting element 30 such as a chip inductor. The feeder line 27 is connected to the adjacent ground pattern 22 via an impedance adjusting element 31 such as a chip inductor.

  The back surface 20b of the printed circuit board 20 is also provided with a ground clearance region 28 that is an insulating region having substantially the same shape in plan view as the antenna mounting region 23 on the front surface 20a side. Since various mounting components are not mounted in the ground clearance region 28 on the back surface 20b side, no conductor pattern such as a land is formed. When the printed board 20 is a multilayer board, it is necessary to form such a ground clearance region 28 not only on the back surface 20b but also on the inner layer. That is, it is necessary that the insulating region in which the ground pattern is cut out extends directly below the antenna mounting region 23. Such a mounting structure is referred to as a “ground clearance type”, whereas a structure in which a portion immediately below the antenna mounting region 23 is covered with a ground pattern is referred to as an “on-ground type”.

  The antenna element 10 is mounted in an antenna mounting area 23 wider than a chip antenna formed by removing a part of the ground pattern 22 on the printed circuit board 20. In the case of the ground clearance type, nothing can be mounted under the antenna element 10, so that the board area is widely occupied. However, since the ground plane does not exist at all, the antenna itself (base body) can be reduced in height. On the other hand, in the case of the on-ground type, since the ground surface is provided in the mounting surface and the lower region, the antenna element is taller than the ground clearance type. For example, the surface of the multilayer board is used as the antenna mounting surface. By making the inner layer a ground pattern layer, the back surface of the multilayer board can be used as a component mounting region.

As shown in FIG. 1, when the antenna element 10 is mounted on the printed circuit board 20, one end of each of the first and second radiation conductors 12 and 13 is connected to the feed line 27 via capacitive coupling between the lands 24 and 25. Connected. Since capacitive coupling due to the gap g exists between the feed line and the first and second radiation conductors 12 and 13, impedance matching is facilitated. The first and second radiation conductors 12 and 13 are supplied with a feeding current from a feeding line 27, and the feeding current is radiated from the first or second radiation conductor. Here, when the feeding current is a signal having the first frequency f ₁ , it is radiated as an electromagnetic wave from the first radiation conductor 12, and when the feeding current is a signal having the second frequency f ₂ , the second radiation is emitted. Radiated as electromagnetic waves from the conductor 13.

  FIG. 5 is a schematic diagram showing a radiation path of radio waves from the first and second radiation conductors 12 and 13.

  As shown in FIG. 5, radio waves (electromagnetic waves) radiated from the first radiating conductor 12 and the second radiating conductor 13 pass through the substrate 11 and are radiated to the outside. Here, since the second radiating conductor 13 is farther from the edge 20e of the substrate 20 than the first radiating conductor 12, the radio wave passes through the base 11 and reaches the free space outside the edge 20e. The route becomes longer. In the case of the antenna element 10 in the present embodiment, the path of the radio wave radiated from the second radiating conductor 13 is not easily obstructed by the base 11 due to the hollow portions 17 a and 17 b. Therefore, the radiation efficiency of the second radiation conductor 13 on the side far from the edge 20e of the printed circuit board 20 can be improved.

  As described above, the antenna device 100 according to the present embodiment has a relatively large cavity (second cavity 17b) immediately below the base 12 on which the high-frequency antenna element ANT2 is formed. A relatively small cavity (first cavity 17a) is provided immediately below the base 11 on which the antenna element T1 on the side is formed. Therefore, even if a high-frequency side antenna having a high resonance frequency is configured using a high dielectric constant substrate, it is not necessary to significantly shorten the antenna length, and a reduction in radiation efficiency of the high-frequency side antenna can be prevented. . That is, when the thickness of the high dielectric constant substrate is reduced on the high frequency side, the antenna length can be made relatively long even when a high resonance frequency is to be obtained. Therefore, the high frequency side antenna element is not downsized more than necessary, and the radiation characteristics of the high frequency side antenna element can be improved.

  The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention, and it goes without saying that these are also included in the present invention. .

For example, in the above-described embodiment, the first and second radiation conductors 13 and 14 and the terminal electrodes 14 to 16 are formed on the base 11, but other conductor patterns may be formed. Further, in the above embodiment that although the case having two antenna elements having a resonant frequencies f _1, f _2, and the present invention is not limited to such a case, the number of antenna elements May be three or more. In that case, the height of the cavity is further stepped.

  Moreover, in the said embodiment, as long as said conductor pattern is formed in each surface of a base | substrate, the corner part may be notched. Further, the conductor pattern formed on the surface of the substrate is not limited to the radiation conductors 12 and 13 and the terminal electrodes 14 to 16, and other conductor patterns may be additionally formed.

DESCRIPTION OF SYMBOLS 10 Antenna element 11 Base | substrate 12 1st radiation conductor 13 2nd radiation conductor 14,15,16 Terminal electrode 17a, 17b Cavity part 20 Board | substrate 22 Ground pattern 23 Antenna mounting area 24, 25, 26 Land 27 Feed line 28 Ground clearance Area 100 Antenna device

Claims (4)

An antenna element and a printed circuit board on which the antenna element is mounted;
The antenna element is
A substrate made of a substantially rectangular parallelepiped dielectric,
A first radiation conductor that resonates at a first resonance frequency formed on at least the upper surface of the substrate;
A second radiation conductor that resonates at a second resonance frequency higher than the first resonance frequency formed on at least the upper surface of the base together with the first radiation conductor;
The substrate is
A first cavity provided below the first radiation conductor and having a first height from the bottom surface of the base;
A second cavity provided below the second radiation conductor and having a second height higher than the first height from the bottom surface of the base body;
The first and second radiation conductors are strip-like patterns parallel to each other and are provided along the longitudinal direction of the base body.
One ends of the first and second radiation conductors are connected to a power supply line provided on the printed circuit board,
The antenna device characterized in that the other ends of the first and second radiation conductors are open ends, and the open ends both end at the ridge line position of the base. The antenna mounting area where the antenna element is mounted is provided in contact with the edge of the printed circuit board,
The first radiation conductor is located on a side near the edge of the printed circuit board, and the second radiation conductor is located on a side far from the edge of the printed circuit board. Antenna device. The base has first and second feet provided at both ends in the longitudinal direction of the base, and the first foot located on the open end side of the first and second radiation conductors. The antenna device according to claim 1, wherein a width S ₁ of the antenna is λg / 20 or more (λg is an effective wavelength of the second resonance frequency). The base has first and second feet provided at both ends in the longitudinal direction of the base, and the width of the second foot located on the power feeding side of the first and second radiation conductors. the antenna device according to any one of claims 1 to 3, characterized in that S ₂ is equal to or less than the first height above the second height.

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