JP2006279515A - Antenna system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna system which has wide directivity while being small in size and simple in configuration and can transmit or receive radio waves of a plurality of wavelengths. <P>SOLUTION: An antenna 100 is equipped with dipole antennas A1 and A2 which are provided at an interval λ1/2 and can send and receive a radio wave of wavelength λ1 and dipole antennas A3 and A4 which are provided at an interval λ2/2 and can send and receive a radio wave of wavelength λ2. The dipole antennas A1 and A2 are fed in phase from feeders and the dipole antennas A3 and A4 are fed in phase from feeders, so that the antenna 100 can send and receive the radio waves of different wavelengths λ1 and λ2 and has bidirectionality along a Z axis. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an antenna device, and more particularly to an antenna device capable of transmitting and receiving a plurality of radio waves having different wavelengths.

  In recent years, wireless local area networks (LANs) have become widespread. Radio waves in the 2.4 GHz band and the 5.2 GHz band are used for the wireless LAN. Not only wireless LAN products compatible with the 2.4 GHz band, which has a high penetration rate, but also wireless LAN products compatible with the 5.2 GHz band and wireless compatible with both 2.4 GHz / 5.2 GHz bands. Many products for LAN are put on the market. In particular, recently, antennas that can be used in both the 2.4 / 5.2 GHz band have begun to be shipped.

As a multi-frequency shared antenna corresponding to a plurality of frequency bands, for example, in Japanese Patent Application Laid-Open No. 2003-309424 (Patent Document 1), a ground plane and layers for different frequencies are stacked above the ground plane at intervals. A plurality of patch antenna elements, a plurality of conductive indicating means for instructing the central portion of the patch antenna elements to a patch antenna element or a ground plane below the patch antenna elements, and a plurality of patch antenna elements connected to predetermined positions of the patch antenna elements A multi-frequency shared antenna comprising power feeding means is disclosed. This multi-frequency shared antenna is small in size and has a feature that radio waves of each frequency can be transmitted and received satisfactorily even if the difference between two frequencies to be transmitted and received is 1 GHz or more.
JP 2003-309424 A

  The antenna disclosed in Japanese Patent Application Laid-Open No. 2003-309424 (Patent Document 1) has a complicated structure in which patch antennas are stacked, so that it is not easy to manufacture and includes a large number of parts. have. Although this antenna has a single directivity, the antenna for a wireless LAN needs to receive a radio wave from various directions and transmit a radio wave in various directions, so a wide directivity is required. In some cases, a single directivity is disadvantageous.

  An object of the present invention is to provide an antenna device that has a wide directivity and can transmit or receive radio waves of a plurality of wavelengths while having a small and simple configuration.

  In summary, the present invention is an antenna device that includes a dielectric, a first feed line, a second feed line, and a pair of first dipole antennas. The dielectric has first and second major surfaces. The first feed line is provided on the first main surface and has a first feed point. The second feed line is provided on the second main surface in parallel with the first feed line, and is close to the first feed point when viewed from a predetermined direction perpendicular to the first main surface. The position has a second feeding point. The pair of first dipole antennas has a first wavelength on both sides of the axis on the first main surface passing through the first feeding point and perpendicular to the first feeding line when viewed from a predetermined direction. Are separated from each other and equidistant from the axis. The pair of first dipole antennas transmit or receive a first radio wave having a first wavelength that is fed by the first and second feed lines.

  Each of the pair of first dipole antennas is provided on the first main surface, and is arranged on one side with respect to the first feed line, and on the second main surface And a second dipole element disposed on the other side with respect to the first feed line when viewed from a predetermined direction.

  The antenna device further includes a pair of second dipole antennas. The pair of second dipole antennas are provided on both sides of the axis at a distance of half the second wavelength different from the first wavelength and equidistant from the axis when viewed from a predetermined direction. And transmitting or receiving a second radio wave having a second wavelength that is fed by the first and second feed lines.

  Each of the pair of second dipole antennas has a third dipole element disposed on the same side as the first dipole element with respect to the first feed line on the first main surface, and a second dipole antenna, A fourth dipole element provided on the main surface and disposed on the same side as the second dipole element with respect to the first feed line when viewed from a predetermined direction.

  Preferably, the line width of the first feed line and the line width of the second feed line are equal to each other.

  More preferably, each of the first to fourth dipole elements is a rectangle in which a long side is provided in the axial direction and a short side is provided in a direction along the first feed line.

  More preferably, the first radio wave and the second radio wave are radio waves having different frequency bands.

  More preferably, the frequency band of the first radio wave is a 2.4 GHz band, and the frequency band of the second radio wave is a 5.2 GHz band.

  More preferably, the first radio wave and the second radio wave are radio waves in the same frequency band.

  According to the antenna device of the present invention, a pair of dipole antennas are provided corresponding to radio waves having a plurality of different wavelengths. The pair of dipole antennas are arranged with a distance of half the wavelength of the corresponding radio wave, and have bidirectional directivity by being fed in the same phase. Therefore, according to the antenna device of the present invention, an antenna device that can transmit and receive radio waves of a plurality of wavelengths and has a wide directivity can be realized.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

  FIG. 1 is a plan view of an antenna device of the present invention as viewed from the front. FIG. 2 is a plan view of the antenna device of the present invention as viewed from the back.

  Referring to FIGS. 1 and 2, antenna 100 is an antenna that is used in, for example, a wireless LAN and corresponds to both the 2.4 GHz band and the 5.2 GHz band. The antenna 100 includes a dielectric substrate 1 having a front surface and a back surface. In place of dielectric substrate 1, a dielectric film having a front surface and a back surface may be used.

  The antenna 100 further includes a feed line 2A provided on the front surface and having a feed point F1, and a feed line 2B provided on the back surface and parallel to the feed line 2A. The feed line 2B has a feed point F2 provided at a position close to the feed point F1 when viewed from the direction perpendicular to the surface of the dielectric substrate. 1 and 2, the direction along the feed lines 2A and 2B is taken as the X axis, the direction passing through the feed point F1 and perpendicular to the X axis is taken as the Y axis, and the direction perpendicular to the surface of the dielectric substrate 1 is taken as the Z axis. The direction. The feed lines 2A and 2B are parallel two lines having the same line width, and constitute a so-called Rehel line.

  Antenna 100 further includes dipole antennas A1 to A4. The dipole antennas A1 and A3 are provided on one side with respect to the Y axis when viewed from the Z axis, and the dipole antennas A2 and A4 are disposed on the other side with respect to the Y axis when viewed from the Z axis. Provided. That is, the dipole antennas A1 and A2 are provided on both sides of the Y axis. Similarly, dipole antennas A3 and A4 are provided on both sides of the Y axis.

  Each of the dipole antennas A1 to A4 is fed by feed lines 2A and 2B. Dipole antennas A1 and A2 are a pair of half-wave dipole antennas that transmit or receive a first radio wave having wavelength λ1, and dipole antennas A3 and A4 transmit or receive a second radio wave having a wavelength λ2 different from wavelength λ1. A pair of half-wave dipole antennas to receive. For example, it is assumed that the first radio wave is a 2.4 GHz band radio wave, and the second radio wave is a 5.2 GHz band radio wave. In this case, the wavelengths λ1 and λ2 are set to 120 mm and 60 mm, respectively.

  The dipole antennas A1 and A2 are provided at a distance of half the wavelength λ1 from each other and equidistant from the Y axis. Therefore, when λ1 = 120 mm, the distance D1 between the dipole antenna A1 and the dipole antenna A2 is 60 mm. Similarly, each of the dipole antennas A3 and A4 is provided at an equal distance from the Y-axis with a distance D2 that is half the wavelength λ2 from each other. If the wavelength λ2 is 60 mm, the distance D2 is 30 mm.

  Dipole antenna A1 includes dipole elements 11A and 11B. Dipole antenna A2 includes dipole elements 11C and 11D. The dipole elements 11A and 11C are provided on the surface of the dielectric substrate 1, and each end is connected to the feed line 2A. Dipole elements 11B and 11D are provided on the back surface of dielectric substrate 1, and each end is connected to feeder line 2B. The dipole elements 11A and 11C are arranged on the same side with respect to the feed line 2A, and the dipole elements 11B and 11D are arranged on the opposite side of the dipole elements 11A and 11C with respect to the feed line 2A when viewed from the Z-axis direction. .

  Dipole antenna A3 includes dipole elements 12A and 12B, and dipole antenna A4 includes dipole elements 12C and 12D. The dipole elements 12A and 12C are provided on the surface of the dielectric substrate 1, and their respective ends are connected to the feed line 2A. Dipole elements 12B and 12D are provided on the back surface of dielectric substrate 1, and each end is connected to feeder line 2B. Each of dipole elements 12A and 12C is arranged on the same side as dipole elements 11A and 11C with respect to feed line 2A, and dipole elements 12B and 12D are arranged on the same side as dipole elements 11B and 11D with respect to feed line 2A.

  Each of the dipole elements 11A to 11D and the dipole elements 12A to 12D has a rectangular shape in which a long side is provided in a direction perpendicular to the feed line and a short side is provided in a direction along the feed line. Specifically, the dipole elements 11A, 11C, 12A, and 12C are provided with long sides along the positive direction of the Y axis and with short sides along the X axis. The dipole elements 11B, 11D, 12B, and 12D have long sides along the negative direction of the Y axis and short sides along the X axis direction.

  The number of dipole elements that can be connected to the feed line 2A and the feed line 2B depends on the maximum width (the maximum length in the X-axis direction) of the dipole elements connected to the feed line. Therefore, if the shape of the dipole element is a trapezoid whose width extends in the X-axis direction, the number of dipole elements that can be connected to the feed line is smaller than that of the antenna device of the present invention. Since the antenna device of the present invention can arrange many dipole elements in the feed line, it can transmit or receive radio waves with more wavelengths than the conventional antenna device.

  The length of the long side of each of the dipole elements 11A to 11D and the dipole elements 12A to 12D, that is, the length of the dipole element is set to about ¼ wavelength. Since each of the dipole antennas A1 to A4 is a half-wave dipole antenna, the length of the dipole element is essentially equal to ¼ wavelength. However, since the dipole element is provided on the dielectric substrate 1 in the antenna device of the present invention, the length of the dipole element depends on the dielectric constant of the dielectric substrate 1 and is shorter than ¼ wavelength.

  The antenna 100 is fed by the feeding cable 4. The feeding cable 4 is a coaxial cable, for example. The antenna 100 is further provided on the front surface of the dielectric substrate 1, and is provided on the back surface of the dielectric substrate 1 corresponding to the conductive line 6A to which the coaxial line of the feeder cable 4 is connected, and the conductive line 6A. A transmission line 6B having the same line width as the line 6A is provided. An outer conductor of the feeder cable 4 is connected to the conductive line 6B. The conductive line 6A and the conductive line 6B constitute a Rehel line.

  1 and 2, the coaxial line of the feeding cable 4 is shown as being connected to the conduction line 6A. However, the coaxial line of the feeding cable 4 is connected to the conduction line 6B, and the external conductor is connected to the conduction line 6A. May be. The characteristics of the antenna 100 in this case are the same as the characteristics when the coaxial line is connected to the conductive line 6A. Hereinafter, the coaxial line of the feeding cable 4 is described as being connected to the conductive line 6A.

  The antenna 100 further includes a transformer 8A provided between the conduction line 6A and the feed line 2A, and a transformer 8B provided between the conduction line 6B and the feed line 2B. The transformers 8A and 8B have the same line width and constitute a Rehel line. Here, the transformer 8A and the transformer 8B are provided in order to match the impedance of the feeding cable connected to one end of the conduction line 6A and the conduction line 6B. The length of each of the transformers 8A and 8B in the Y-axis direction is set to an optimum length for impedance matching.

  Each of dipole antennas A1 to A4, feed lines 2A and 2B, conductive lines 6A and 6B, and transformers 8A and 8B are coated with a photoresist on, for example, metal foil provided on the front and back surfaces of dielectric substrate 1. Then, each shape is transferred to a photoresist by a mask process, and then etched to form a predetermined shape.

  Hereinafter, the operation of the antenna 100 will be described. The dipole antennas A1 and A2 are provided at equal intervals from the feed points F1 and F2, and the interval between these dipole antennas is ½ of the wavelength λ1, which is the radiation wavelength. When power is supplied to the feeding points F1 and F2, the dipole antennas A1 and A2 are excited with the same phase and equal amplitude, and radiate a radio wave having a wavelength λ1. In this case, for example, regarding the radio wave radiated from one of the dipole elements 11A and 11C and the radio wave radiated from the other element, the electric field components in the X-axis direction have opposite phases and are canceled out. The electric field components in the Z-axis direction that are equidistant from each of the dipole elements 11A and 11C intensify in the same phase, so that strong radiation is generated in the Z-axis direction, and the directivity becomes bi-directional (8-shaped). The same applies to the dipole elements 11B and 11D. The electric field components in the X-axis direction are reversed in phase with each other, cancel out strongly, generate strong radiation in the Z-axis direction, and have directivity of bi-directionality (eight-shape).

  Note that when the dipole antennas A1 and A2 receive radio waves, they are the same as when radio waves are transmitted, radio waves that arrive from the Z-axis direction can be strongly received, and the directivity becomes bi-directional.

  Furthermore, the same phenomenon occurs when the dipole antennas A3 and A4 transmit or receive radio waves with the wavelength λ2 as when the dipole antennas A1 and A2 transmit or receive radio waves with the wavelength λ1.

  In summary, the antenna 100 is provided at an interval of λ1 / 2, and is provided at an interval of λ2 / 2 with dipole antennas A1 and A2 capable of transmitting and receiving an electromagnetic wave of wavelength λ1, and transmits and receives an electric wave of wavelength λ2. Possible dipole antennas A3 and A4 are provided. Since the dipole antennas A1 and A2 are fed in phase from the feed lines 2A and 2B and the dipole antennas A3 and A4 are fed in phase from the feed lines 2A and 2B, the antenna 100 transmits and receives radio waves having different wavelengths λ1 and λ2. Becomes possible, and it can have bidirectionality in the Z-axis direction. Therefore, the antenna device of the present invention can transmit or receive radio waves of a plurality of wavelengths and can have a wide directivity.

  As described above, the antenna 100 can be used as a multi-frequency shared antenna that can transmit and receive radio waves in different frequency bands, but the wavelengths λ1 and λ2 may be wavelengths in the same frequency band. In this case, since the antenna 100 can transmit and receive radio waves having different wavelengths in the same frequency band, the radio wave can be transmitted or received over a wide frequency range in the same frequency band.

  Furthermore, the antenna device of the present invention is not limited to an antenna for a wireless LAN, and can be used in various frequency bands. For example, the antenna device of the present invention may be an antenna that transmits or receives radio waves in the UHF (Ultra High Frequency) band. However, the wavelength of the UHF band radio wave is longer than that of the 2.4 GHz band radio wave. In order to use the antenna device of the present invention as an antenna for the UHF band, it is necessary to set the distance D1 to, for example, 300 mm. Therefore, if the installation space is sufficient, the antenna device of the present invention can be used for transmission or reception of radio waves in the UHF band.

  FIG. 3 is a diagram illustrating the gain of the antenna 100 of FIG. With reference to FIG. 3, the antenna gain in each band of 2.4 GHz band and 5.2 GHz band is shown. In FIG. 3, bands B1 and B2 indicate bands that are actually used for wireless LANs or the like currently in the 2.4 GHz band and the 5.2 GHz band, respectively. The frequency range indicated by the band B1 is 2.45 ± 0.05 GHz, and the frequency range indicated by the band B2 is 5.2 ± 0.05 GHz.

  As the dielectric substrate 1 of the antenna 100, a glass epoxy substrate having a thickness of 0.8 mm is used. Moreover, since the transformers 8A and 8B perform impedance matching in both the 2.4 GHz band and the 5.2 GHz band, the length of each transformer is intermediate between the 2.4 GHz band and the 5.2 GHz band. It was set to 1/4 of the center wavelength (about 80 mm) in the 8 GHz band. As shown in FIG. 3, the gain of the antenna is about 6.3 dBi in the 2.4 GHz band, and is about 7.7 dBi at 5.2 GHz.

  FIG. 4 is a diagram showing the VSWR (voltage standing wave ratio) of the antenna 100 of FIG. Referring to FIG. 4, the value of VSWR in each frequency band of 2.4 GHz band and 5.2 GHz band is shown. In FIG. 4, bands B1 and B2 correspond to bands B1 and B2 in FIG. 3, respectively. A lower value of VSWR indicates that there is less power loss when power is supplied from the transmission circuit to the antenna. As shown in FIG. 4, VSWR is 1.5 or less in each of the 2.4 GHz band and the 5.2 GHz band.

  FIG. 5 is a diagram illustrating the horizontal plane directivity of the antenna 100 of FIG. The horizontal plane refers to FIGS. 1 and 2XZ plane. Referring to FIG. 5, the horizontal plane directivity of antenna 100 when the frequency band is 2.4 GHz band is shown. In FIG. 5, the direction of 0 degrees indicates the positive direction of the Z axis in the antenna 100 of FIG. 1, and the direction of -180 degrees indicates the negative direction of the Z axis. As shown in FIG. 5, the antenna 100 has bi-directionality (eight-shaped directivity) that radiates radio waves strongly in the front-rear direction, that is, in the 0-degree direction and the −180-degree direction.

  FIG. 6 is another diagram showing the horizontal plane directivity of the antenna 100 of FIG. Referring to FIG. 6, the horizontal plane directivity of antenna 100 when the frequency band is the 5.2 GHz band is shown. The directions of 0 degrees and −180 degrees shown in FIG. 6 are the same as the directions of 0 degrees and −180 degrees shown in FIG. As shown in FIG. 6, even in the 5.2 GHz band, the antenna 100 has bi-directionality that radiates radio waves strongly in the 0 degree direction and the -180 degree direction.

  Note that the antenna device of the present invention can also be applied when transmitting and receiving radio waves of three or more different wavelengths.

  FIG. 7 is a plan view of a first modification of the antenna device of the present invention as seen from the table. FIG. 8 is a plan view of the first modification of the antenna device of the present invention as seen from the back. Referring to FIGS. 7 and 8, antenna 100A is different from antenna 100 of FIG. 1 in that it further includes dipole antennas A5 and A6 that can transmit or receive a radio wave of wavelength λ3, which is the third wavelength. Since the configuration of the other part of antenna 100A is the same as the configuration of the corresponding part of antenna 100, the following description will not be repeated.

  The dipole antenna A5 and the dipole antenna A6 are fed by feed lines 2A and 2B, and are separated from each other by a distance D3 that is a distance half the wavelength λ3. The distance D3 corresponds to, for example, a 3.8 GHz band that is an intermediate frequency band between the 2.4 GHz band and the 5.2 GHz band, and is set to about 40 mm.

  Dipole antenna A5 includes dipole elements 13A and 13B, and dipole antenna A6 includes dipole elements 13C and 13D. The dipole elements 13A and 13C are provided on the surface of the dielectric substrate 1, and their respective ends are connected to the feed line 2A. Dipole elements 13B and 13D are provided on the back surface of dielectric substrate 1, and each end is connected to feeder line 2B. Each of dipole elements 13A and 13C is arranged on the same side as dipole elements 11A, 11C, 12A and 12C with respect to feed line 2A. The dipole elements 13B and 13D are arranged on the same side as the dipole elements 11B, 11D, 12B, and 12D with respect to the feed line 2B.

  The antenna 100A can transmit and receive radio waves in each frequency band of 2.4 GHz band, 3.8 GHz band, and 5.2 GHz band. Further, the antenna 100A has bidirectionality in the Z-axis direction in each frequency band.

  Currently, there is no need for wireless communication using radio waves in the 3.8 GHz band, but the antenna 100A can easily cope with wireless communication in the 3.8 GHz band in the future. If the distance D3 is half the wavelength λ2 and the distance D2 is set shorter than the distance D3, there is a need for communication using radio waves in a frequency band higher than the 5.2 GHz band. Even if it occurs in the future, the antenna 100A can easily cope with it.

  FIG. 9 is a plan view of a second modification of the antenna device of the present invention as seen from the table. FIG. 10 is a plan view of the second modification of the antenna device of the present invention viewed from the back. Referring to FIGS. 9 and 10, antenna 100B differs from antenna 100 of FIG. 1 in that dipole element groups 31A and 31B are provided on feed line 2A, and dipole element groups 31C and 31D are provided on feed line 2B. . Since the configuration of other parts of antenna 100B is the same as that of antenna 100 in FIG. 1, the following description will not be repeated.

  Each of dipole element groups 31A to 31D includes nine dipole elements. The configurations of dipole element groups 31A to 31D are equal to each other. Hereinafter, the configuration of dipole element group 31A will be described as a representative, and the configuration of each of dipole element groups 31B to 31D will not be repeated.

  Dipole element group 31A includes dipole elements 11A to 19A. The dipole element 11A is a dipole element that constitutes a dipole antenna that supports transmission and reception of radio waves in the 2.4 GHz band. The dipole element 12A is a dipole element that constitutes a dipole antenna that can transmit and receive a 5.2 GHz band radio wave. Seven dipole elements having different lengths are provided between the dipole element 11A and the dipole element 12A.

  Thus, by providing as many dipole elements with different lengths as possible within the limitation of the length of the feed line, the antenna device of the present invention can transmit and receive radio waves in a wider band. The antennas 100A and 100B may be used as antennas for transmitting and receiving radio waves in a certain frequency band (for example, UHF band and 2.4 GHz band) by appropriately setting the length of the dipole element.

  As described above, according to the embodiment of the present invention, a pair of dipole antennas operating in the same frequency band are arranged with a distance half the center wavelength of the frequency band, and are fed in phase from the feed line. Thus, bidirectional directivity can be obtained. Further, according to the embodiment of the present invention, it is possible to transmit / receive radio waves of a plurality of wavelengths by providing a plurality of pairs of dipole antennas for transmitting / receiving radio waves of different wavelengths on the feed line. Therefore, according to the antenna device of the present invention, a wide directivity can be obtained and a radio wave having a plurality of wavelengths can be transmitted and received while having a small and simple configuration.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is the top view which looked at the antenna apparatus of this invention from the table | surface. It is the top view which looked at the antenna apparatus of this invention from the back. It is a figure explaining the gain of the antenna 100 of FIG. It is a figure which shows VSWR (voltage standing wave ratio) of the antenna 100 of FIG. It is a figure which shows the horizontal surface directivity of the antenna 100 of FIG. It is another figure which shows the horizontal surface directivity of the antenna 100 of FIG. It is the top view which looked at the 1st modification of the antenna apparatus of this invention from the table | surface. It is the top view which looked at the 1st modification of the antenna apparatus of this invention from the back. It is the top view which looked at the 2nd modification of the antenna apparatus of this invention from the table | surface. It is the top view which looked at the 2nd modification of the antenna apparatus of this invention from the back.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Dielectric substrate, 2A, 2B feeder line, 4 feeder cable, 6A, 6B conduction line, 8A, 8B transformer, 11A-11D, 12A-12D, 13A-13D, 14A-19A dipole element, 31A-31D dipole element Group, 100, 100A, 100B antenna, A1-A6 dipole antenna, B1, B2 band, D1-D3 distance, F1, F2 feed point.

Claims (6)

An antenna device,
A dielectric having first and second major surfaces;
A first feed line provided on the first main surface and having a first feed point;
The second main surface is provided in parallel with the first power supply line, and when viewed from a predetermined direction perpendicular to the first main surface, the second main surface is in a position close to the first power supply point. A second feed line having two feed points;
When viewed from the predetermined direction, a distance of half of the first wavelength is set on both sides of the axis on the first main surface passing through the first feeding point and perpendicular to the first feeding line. A pair of first dipoles that are spaced apart and equidistant from the axis and that are fed by the first and second feed lines to transmit or receive a first radio wave having the first wavelength With an antenna,
Each of the pair of first dipole antennas is
A first dipole element provided on the first main surface and disposed on one side with respect to the first feed line;
A second dipole element provided on the second main surface and disposed on the other side with respect to the first feeder line when viewed from the predetermined direction;
The antenna device is
When viewed from the predetermined direction, they are provided on both sides of the axis at a distance of half the second wavelength different from the first wavelength and equidistant from the axis. A pair of second dipole antennas for transmitting or receiving a second radio wave having the second wavelength fed by a second feeder line;
Each of the pair of second dipole antennas is
A third dipole element disposed on the same side as the first dipole element with respect to the first feed line on the first main surface;
A fourth dipole element provided on the second main surface and disposed on the same side as the second dipole element with respect to the first feed line when viewed from the predetermined direction; Including an antenna device.   The antenna device according to claim 1, wherein a line width of the first feed line and a line width of the second feed line are equal to each other.   The shape of each of the first to fourth dipole elements is a rectangle in which a long side is provided in the axial direction and a short side is provided in a direction along the first feed line. Antenna device.   4. The antenna device according to claim 1, wherein the first radio wave and the second radio wave are radio waves having different frequency bands. 5. The frequency band of the first radio wave is a 2.4 GHz band,
The antenna device according to claim 4, wherein a frequency band of the second radio wave is a 5.2 GHz band.   The antenna device according to any one of claims 1 to 3, wherein the first radio wave and the second radio wave are radio waves in the same frequency band.

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