Antenna device

Abstract

This antenna device includes: a ground element having a shape with a longitudinal direction and a lateral direction; a first antenna element having a first power feeding part, a first erected part formed so as to rise from the first power feeding part, and a first arm part extending along the longitudinal direction from the first erected part; and a first parasitic element connected to a first end part of the ground element in the lateral direction and extending along the longitudinal direction of the ground element. The first end part is located in the vicinity of the first power feeding part in a plan view.

Description

Antenna device

[0001] The present invention relates to an antenna device.

[0002] For example, Patent Document 1 discloses an antenna device including an antenna and a substrate.

[0003] JP 2009-267765 A

[0004] However, for example, when the frequency band supported by an antenna is widened, the size of the antenna device may become large.

[0005] One example of an object of the present invention is to reduce the size of an antenna device while widening the frequency range that the antenna can handle. Other objects of the present invention will become apparent from the description of this specification.

[0006] One aspect of the present invention is an antenna device comprising: a ground element having a shape having a longitudinal direction and a width direction; a first feed portion; a first standing portion formed to rise from the first feed portion; and a first arm portion extending from the first standing portion along the longitudinal direction; and a first parasitic element connected to a first end portion of the ground element in the width direction and extending along the longitudinal direction of the ground element, wherein the first end portion is located near the first feed portion in a planar view.

[0007] According to the above aspect of the present invention, it is possible to reduce the size of the antenna device while widening the frequency band that the antenna can handle.

[0008] 1. An exploded perspective view of the antenna device 10. An exploded perspective view of the antenna unit 22. A plan view of the antenna unit 22. A diagram for explaining details of the ground plate 30, the substrate 50, the substrate 52, the cable 51, and the cable 53. A diagram for explaining details of the ground plate 30, the first antenna element 70, and the second antenna element 71. A diagram for explaining the inside of the housing 20. A cross-sectional view taken along the line A-A in FIG. 1. A diagram showing frequency characteristics of VSWR of the first antenna element 70 and the second antenna element 71. A diagram showing frequency characteristics of VSWR of the first antenna element 70 and the second antenna element 71. A diagram showing frequency characteristics of the correlation coefficient of the first antenna element 70 and the second antenna element 71.

[0009] At least the following matters will become clear from the description of this specification and the accompanying drawings.

[0010] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The same or equivalent components, members, etc. shown in each drawing are designated by the same reference numerals, and redundant explanations will be omitted where appropriate.

[0011] ==Antenna Device 10== <<Definition of Directions, Etc.>> First, directions, etc. in the antenna device 10 will be defined with reference to FIGS. 1, 2, and 3. FIG.

[0012] Directions parallel to the ground plate 30 (described later) and perpendicular to each other are referred to as the "+X direction" and the "+Y direction." In this embodiment, as shown in FIGS. 1 and 2 , the +X direction is the direction from the first antenna element 70 (described later) to the second antenna element 71 (described later). The +Y direction is the direction in which the arm of the first antenna element 70 extends. The +Z direction is the normal direction to the ground plate 30, and is the direction from the surface of the ground plate 30 facing the cover 21 (described later) to the surface of the ground plate 30 facing the housing 20. The surface of a component such as the ground plate 30 facing in the +Z direction is referred to as the "front surface," and the surface facing in the -Z direction is referred to as the "rear surface."

[0013] The direction opposite to the +X direction (here, the direction from the second antenna element 71 toward the first antenna element 70) is referred to as the "-X direction." The term may refer to both the +X direction and the -X direction, or may simply refer to either the +X direction or the -X direction as the "X direction." Similarly to the -X direction and X direction relative to the +X direction, the "-Y direction" and "Y direction" relative to the +Y direction, and the "-Z direction" and "Z direction" relative to the +Z direction are also defined.

[0014] 1, 2, and 3, the +X direction, +Y direction, and +Z direction are each represented by a line segment with an arrow to facilitate understanding of directions and the like in the antenna device 10. Note that the intersection of these line segments with an arrow does not mean the origin of the coordinate system.

[0015] The antenna device 10 of this embodiment is disposed so that the +Z direction is the zenith direction. Therefore, in the following description, the +Z direction may be referred to as the "zenith direction" or "upward direction," and the -Z direction may be referred to as the "downward direction." Furthermore, the direction parallel to the XY plane (i.e., the direction parallel to the front surface) may be referred to as the "plane direction," and the Z direction may be referred to as the "up-down direction" or "height direction."

[0016] Furthermore, in the following description, "connected" is not limited to being physically connected, but also includes being electrically connected. Therefore, "connected" is not limited to being connected by a conductor, but also includes being connected via an electronic circuit, electronic component, etc.

[0017] <<Outline of Antenna Device 10 >> Next, an outline of the antenna device 10 of this embodiment will be described with reference to FIG.

[0018] FIG. 1 is an exploded perspective view of an antenna device 10. The antenna device 10 is a device used in, for example, a vehicle (not shown). The antenna device 10 is disposed, for example, inside the instrument panel of the vehicle. However, the location of the vehicle where the antenna device 10 is disposed can be changed as appropriate depending on environmental conditions such as the intended communication target. The antenna device 10 may be disposed in various locations, such as the roof of the vehicle, above the dashboard, an overhead console, a bumper, a license plate attachment portion, a pillar portion, or a spoiler portion. The antenna device 10 may also be an antenna device other than one for use in a vehicle.

[0019] The antenna device 10 includes a housing 20 , a cover 21 , and an antenna unit 22 .

[0020] The housing 20 and the cover 21 are members that form a housing space that houses the antenna unit 22. The housing 20 and the cover 21 are members that are molded from, for example, resin, as will be described in detail later.

[0021] The antenna unit 22 is a unit including a plurality of antennas, and as shown in Fig. 2, the antenna unit 22 has a ground plate 30, a first parasitic element 40, a second parasitic element 41, substrates 50 and 52, cables 51 and 53, a planar antenna 60, a first antenna element 70, a second antenna element 71, and tapes 80 and 81.

[0022] <Ground Plate> As shown in Fig. 1 , the ground plate 30 is disposed on the front surface of the cover 21, which is the surface on the +Z direction side, and functions as a ground for the antenna unit 22. The ground plate 30 shown in Fig. 2 is formed by processing a metal plate (sheet metal). Note that the ground plate 30 may be formed from a material other than a plate-shaped material as long as it functions as a ground for the antenna unit 22.

[0023] The ground plate 30 may be formed by freely combining metal and non-metallic members. For example, the ground plate 30 may include a metal plate and a resin insulator. The ground plate 30 may be formed of a single printed circuit board (PCB) on which a conductor pattern is formed, or may be formed of multiple boards.

[0024] 3, the ground plate 30 has a substantially rectangular main body 300, and extensions 321 and 322, a wall 323, a clamping portion 324, and protrusions 325a, 325b, and 325c located on the -X side of a central axis C (described below) of the main body 300. The ground plate 30 also has extensions 331 and 332, a wall 333, a clamping portion 334, and protrusions 335a, 335b, and 335c located on the +X side of the central axis C of the main body 300. Here, the Y direction of the ground plate 30 corresponds to the "longitudinal direction," and the X direction of the ground plate 30 corresponds to the "width direction."

[0025] 3, the main body 300 is a main part of the ground plate 30, which has a substantially rectangular shape in a plan view seen from the +Z direction. The width direction of the main body 300 is parallel to the X direction. The length direction of the main body 300 is parallel to the Y direction. "Substantially rectangular" refers to a shape consisting of four sides, including, for example, a square or a rectangle. For example, at least some of the corners may be cut out at an angle to the sides, or at least some of the corners may include a curve.

[0026] The main body 300 has a shape that is line-symmetrical with respect to a central axis C that passes through the geometric center (not shown) of the main body 300 and is parallel to the Y direction. Therefore, first, the extensions 321 and 322, wall 323, clamping portion 324, and protrusions 325a, 325b, and 325c that are located on the −X side of the central axis C of the main body 300 will be described.

[0027] The extension portion 321 is a portion that increases the electrical length of the ground plate 30 in the +Y direction. As shown in FIG. 4 , the extension portion 321 is formed on the front surface of the ground plate 30 so as to extend from the end of the main body 300 in the +Y direction in the +Z direction. The extension portion 321 is formed at one of the two ends of the ground plate 30 in the Y direction that is farther from the first power supply portion 701 (described later), thereby increasing the electrical length of the ground plate 30. Note that the extension portion 321 may also be formed so as to extend in the −Z direction.

[0028] The extension portion 322 is a portion provided to increase the area of ​​the ground plate 30 in order to improve the characteristics of the planar antenna 60 (described later). The extension portion 322 is formed to extend from the end of the main body 300 on the −X direction side toward the −X direction. As shown in FIG. 3 , the extension portion 322 is formed in the Y direction between the end of a first arm portion 703 (described later) of the first antenna element 70 and the end of an arm portion 401 of the first parasitic element 40.

[0029] 4, the wall portion 323 is a portion for determining the position of the cable 51 together with the clamping portion 324. The wall portion 323 is formed so as to extend in the +Z direction from the end portion on the −X direction side of the main body portion 300. The wall portion 323 is formed at the position where the extension portion 322 is formed at the end portion on the −X direction side of the main body portion 300.

[0030] 4, the clamping portion 324 is a portion that clamps the cable 51 together with the wall portion 323. The clamping portion 324 is formed on the main body portion 300 so as to face the wall portion 323 in the +Z direction.

[0031] 4, the protrusion 325a is inserted into a hole 520a (described later) of the substrate 50 to determine the position of the substrate 50 relative to the ground plate 30. The protrusion 325a is formed to extend in the +Z direction from the front surface of the ground plate 30. Note that the protrusions 325b and 325c have the same characteristics as the protrusion 325a, and therefore detailed description thereof will be omitted here.

[0032] Next, we will explain the extensions 331 and 332, wall 333, clamping portion 334, and protrusions 335a, 335b, and 335c located on the +X side of central axis C of main body 300. As shown in Fig. 3, extensions 331 and 332, wall 333, clamping portion 334, and protrusions 335a, 335b, and 335c are formed so as to be symmetrical with extensions 321 and 322, wall 323, clamping portion 324, and protrusions 325a, 325b, and 325c, respectively, with respect to central axis C.

[0033] That is, for example, when comparing extension portion 331 with extension portion 321, extension portion 331 is similar to extension portion 321 except that extension portion 331 is located on the +X side with respect to central axis C. Extension portion 332, wall portion 333, clamping portion 334, and protrusions 335a, 335b, and 335c are similar to extension portion 322, wall portion 323, clamping portion 324, and protrusions 325a, 325b, and 325c, and therefore detailed description thereof will be omitted here.

[0034] Note that, like the above-described extension portion 331, the portion located on the +X side of the central axis C of the main body portion 300 does not necessarily have to be formed so as to be line-symmetrical with the portion located on the −X side of the central axis C of the main body portion 300. For example, the extension portion 331 may be located in a different position from the extension portion 321 as long as it has the same function as the extension portion 321. Furthermore, the extension portion 331 may have a different shape from the extension portion 321 as long as it has the same function as the extension portion 321.

[0035] 3, the first parasitic element 40 is an element that, when connected to the ground plate 30, widens the frequency band that can be supported by the first antenna element 70. The first parasitic element 40 is connected to a first end 302, which is one of the ends of the ground plate 30 in the −X direction and is located near a first feeding part 701 (described later).

[0036] Here, the "first end 302 located near the first feeding portion 701 (described later)" refers to, for example, a portion including a point where the outer edge on the -X side of the ground plate 30 intersects with an axis (not shown) in the X direction that passes through the first feeding portion 701 (here, hole 501 (described later) in the substrate 50 into which the first feeding portion 701 is inserted) in the plan view shown in Fig. 3. As a result, the first parasitic element 40 connected at the first end 302 essentially functions as a ground extending from the first feeding portion 701 of the first antenna element 70.

[0037] In this embodiment, the first end 302 is the portion of the -X side end of the ground plate 30 that includes the above-mentioned point, but is not limited to this. Specifically, it is sufficient that the first parasitic element 40 is connected to a position of the -X side end of the ground plate 30 that substantially functions as a ground extending from the first feeding portion 701 of the first antenna element 70. The first parasitic element 40 has a connecting portion 400 and an arm portion 401.

[0038] The connecting portion 400 is a portion of the first parasitic element 40 that is connected to the main body portion 300. The connecting portion 400 is formed so as to extend from the first end portion 302 in the −X direction.

[0039] Arm 401 is a portion that extends in the +Y direction from connection portion 400. As will be described in detail later, in this embodiment, the length from first feeding portion 701 to the Y-direction tip of ground plate 30, i.e., the Z-direction end of extension portion 321, is different from the length from first feeding portion 701 to the tip of first parasitic element 40, i.e., the Y-direction end of arm 401. This makes it possible to widen the frequency band supported by first antenna element 70 in this embodiment.

[0040] 3, the second parasitic element 41 is an element that, when connected to the ground plate 30, widens the number of bands that can be supported by the second antenna element 71. The second parasitic element 41 is connected to a second end 303 that is located near a second feed portion 711 (described below) among the +X-direction ends of the ground plate 30. The second parasitic element 41 has a connection portion 410 and an arm portion 411.

[0041] Next, the connecting portion 410 and the arm portion 411 located on the +X side of the central axis C of the main body portion 300 will be described. Here, the connecting portion 410 and the arm portion 411 are formed so as to be linearly symmetrical with the connecting portion 400 and the arm portion 401, respectively, with respect to the central axis C.

[0042] That is, for example, when comparing connection portion 410 with connection portion 400, connection portion 410 is similar to connection portion 400 except that connection portion 410 is located on the +X side with respect to central axis C and is connected to second end portion 303, which is the end portion of ground plate 30 in the +X direction. Furthermore, arm portion 411 has the same characteristics as arm portion 401, and therefore a detailed description thereof will be omitted here.

[0043] Note that the connecting portion 410 and the arm portion 411 located on the +X side of the central axis C of the main body portion 300 do not necessarily have to be formed so as to be line-symmetrical with the connecting portion 400 and the arm portion 401 located on the −X side of the central axis C of the main body portion 300. For example, the connecting portion 410 may be located in a different position from the connecting portion 400 as long as it has the same function as the connecting portion 400. Furthermore, the connecting portion 410 may have a different shape from the connecting portion 400 as long as it has the same function as the connecting portion 400.

[0044] <Substrate> The substrate 50 is an electronic component on which a conductive pattern (not shown) is formed and on which circuit elements are mounted. As shown in Fig. 4, the substrate 50 of this embodiment has a conductive pattern formed thereon that connects the cable 51 and the first antenna element 70. The substrate 50 has holes 500a, 500b, and 500c into which the protrusions 325a, 325b, and 325c formed on the ground plate 30 are inserted, respectively, and a hole 501 into which a first feeding portion 701 (described later) of the first antenna element 70 is inserted.

[0045] The substrate 50 is positioned such that the protrusions 325a, 325b, and 325c are inserted into the three holes 500a, 500b, and 500c, respectively, as viewed from the +Z direction. Thereafter, the protrusions 325a, 325b, and 325c are fixed to the substrate 50 with solder or the like so that the substrate 50 is fixed to the ground plate 30.

[0046] Next, the substrate 52, which is disposed on the +X side of the central axis C of the main body 300, will be described. The substrate 52 is formed so as to be symmetrical to the substrate 50 with respect to the central axis C. The substrate 52 also has holes 520a, 520b, 520c, and a hole 521. Comparing the substrate 52 with the substrate 50, the substrate 52 has the same characteristics as the substrate 50 except that it is located on the +X side of the central axis C, and therefore a detailed description thereof will be omitted here.

[0047] Note that the substrate 52 located on the +X side of the central axis C of the main body 300 does not necessarily have to be formed so as to be line-symmetrical with the substrate 50 located on the −X side of the central axis C of the main body 300. For example, the substrate 52 may be located in a different position from the substrate 50 as long as it has the same function as the substrate 50. Furthermore, the substrate 52 may have a different shape from the substrate 50 as long as it has the same function as the substrate 50.

[0048] 3, the cable 51 is a cable connected to the first antenna element 70 arranged on the substrate 50. In this embodiment, the inner conductor of the cable 51 is connected to the first power supply part 701, and the outer conductor of the cable 51 is connected to a ground (not shown) formed on the substrate 50.

[0049] 3 , the cable 53 is a cable connected to the second antenna element 71 disposed on the substrate 52. In this embodiment, the inner conductor of the cable 53 is connected to the second power supply portion 711, and the outer conductor of the cable 53 is connected to a ground (not shown) formed on the substrate 50.

[0050] <Planar Antenna> The planar antenna 60 is an antenna that supports radio waves in a frequency band for the Global Navigation Satellite System (GNSS), for example. Note that the communication standard and frequency band of radio waves supported by the planar antenna 60 are not limited to GNSS, and other communication standards and frequency bands may be used. For example, the planar antenna 60 may support radio waves in a frequency band for the Satellite Digital Audio Radio Service (SDARS) or a frequency band for V2X.

[0051] The planar antenna 60 may be compatible with a desired circularly polarized wave, or may be compatible with a desired linearly polarized wave such as a vertically polarized wave or a horizontally polarized wave. As shown in Figures 2, 3, and 6, the planar antenna 60 has a substrate 601, a radiating element 602, a dielectric 603, and a shield case 604.

[0052] The substrate 601 is a component on which the dielectric 603 is disposed. A conductive pattern that functions as a ground is formed on the front surface of the substrate 601 on the +Z side. A conductive pattern to which a circuit element (not shown) of the cable 55 is connected is formed on the back surface of the substrate 601 on the -ZZ side. The substrate 601 may also be configured by forming a conductive pattern on a resin material using MID (Molded Interconnect Device) technology.

[0053] The radiating element 602 is a conductive member disposed on the front surface of the dielectric 603. As shown in FIG. 4 , the outer diameter of the radiating element 602 is a quadrilateral in plan view when viewed from the +Z direction. In this embodiment, the outer diameter of the radiating element 602 is a square with equal vertical and horizontal lengths, but it may be rectangular, circular, elliptical, polygonal, or the like. Furthermore, the outer diameter of the radiating element 602 may have a notch (concave portion) or a protrusion (convex portion) formed thereon.

[0054] The radiating element 602 has two power feed points 605, 606. The planar antenna 60 of this embodiment employs a two-feed system. The inner conductors (not shown) of the two cables 55 are connected to the two power feed points 605, 606 via a circuit (not shown). The circuit may be a distribution circuit, an amplifier circuit, a combiner circuit, a phase adjustment circuit, or the like. If no circuit is included, the inner conductor of one cable 55 may be connected to the two power feed points 605, 606.

[0055] The power feeding method of the planar antenna 60 is not limited to the two-feed method. The planar antenna 60 may employ, for example, a four-feed method. In the planar antenna 60 employing the four-feed method, four feed points are formed in the radiating element 602. The planar antenna 60 may employ, for example, a single-feed method. In the planar antenna 60 employing the one-feed method, one feed point is formed in the radiating element 602.

[0056] The dielectric 603 is a member made of a dielectric material such as ceramic. The outer diameter of the dielectric 603 is a quadrilateral in a plan view when viewed from the +Z direction. The outer diameter of the dielectric 603 is not limited to a quadrilateral, and may be, for example, a circle, an ellipse, a polygon, or the like. The radiating element 602 is disposed on the upper side of the dielectric 603. A conductor pattern that functions as a ground conductor film (or ground conductor plate) (not shown) is formed on the back side of the dielectric 603.

[0057] The shield case 604 is a metal member that protects the conductive patterns formed on the back side of the substrate 601 and the electronic components mounted thereon from physical interference with other components and electrically shields them from external noise, etc. The shield case 604 is attached to the back side of the substrate 601. As shown in Figures 2 and 6, the shield case 604 is located between the substrate 601 and the ground plate 30.

[0058] <Antenna Element> As shown in Figures 1 to 5, the first antenna element 70 is a wideband antenna based on a monopole antenna. For the sake of explanation, Figure 5 only shows the ground plate 30, the first parasitic element 40, the second parasitic element 41, the first antenna element 70, and the second antenna element 71. The first antenna element 70 of this embodiment is compatible with radio waves in the 699 MHz to 5000 MHz range for GSM, UMTS, LTE, and 5G, for example. The first antenna element 70 shown in Figure 5 has a first feeding portion 701, a first standing portion 702, a first arm portion 703, and a first extension portion 704.

[0059] 5, the first feeding section 701 is a conductive section including a feeding point. The feeding point is a section that feeds power to the first antenna element 70. The first feeding section 701 is inserted into a hole 501 in the substrate 50 and is connected to a conductive pattern formed on the substrate 50 by soldering or the like.

[0060] The first standing portion 702 is a portion that corresponds to at least the high frequency band of the radio wave frequency band that is supported by the first antenna element 70. In this embodiment, the first standing portion 702 is formed to improve the characteristics of the first antenna element 70 in the high frequency band, particularly in the high frequency band (e.g., 2500 MHz to 5000 MHz). For this reason, the first standing portion 702 is formed to have a length and width that correspond to the wavelength used in the high frequency band, particularly in the high frequency band.

[0061] The first upright portion 702 is formed to rise relative to the front surface of the ground plate 30. In this embodiment, the first upright portion 702 is formed to rise upward (in the +Z direction) from the first power supply portion 701 relative to the front surface of the ground plate 30, as shown in Fig. 5 . In other words, the first upright portion 702 is formed to rise in the normal direction to the front surface 301. Note that the first upright portion 702 is not limited to rising upward relative to the front surface 301, and may be inclined at a predetermined angle relative to the normal direction to the front surface 301.

[0062] The first standing portion 702 has a self-similar shape. Here, a self-similar shape refers to a shape that remains similar even when the scale (size ratio) is changed. This allows the length and width to be set in various ways according to the wavelength used in the radio wave frequency band supported by the first antenna element 70, making it possible to achieve a wider bandwidth. Note that the first standing portion 702 does not have to have a self-similar shape.

[0063] The first arm 703, together with the first parasitic element 40, is a portion that corresponds to at least the low frequency band of the radio wave frequency band that the first antenna element 70 corresponds to. In this embodiment, the first arm 703 is formed to improve the characteristics of the first antenna element 70 in the low frequency band, particularly in the low frequency band (e.g., 700 MHz to 900 MHz). For this reason, the first arm 703 is formed to have a length and width that correspond to the wavelength used in the low frequency band, particularly in the low frequency band.

[0064] The first arm 703 is formed to extend in the +Y direction from the upper end of the first standing portion 702. In this embodiment, as shown in Fig. 5, the first arm 703 is formed to extend in the +Y direction from the end of the first standing portion 702 on the -Y direction side as a starting point. The first arm 703 is connected to the -X direction side of the upper end of the first standing portion 702. Therefore, the first arm 703 is located on the -X direction side of the main body portion 300 in a plan view seen from the +Z direction.

[0065] The first extension portion 704 is formed to improve the bandwidth of the first antenna element 70 in the low frequency band, particularly in the low frequency band (for example, 700 MHz to 900 MHz).

[0066] The first extension portion 704 is formed so as to extend in the -Z direction from the entire region of the end portion on the -X direction side of the first arm portion 703 extending in the Y direction. The first extension portion 704 may be formed so as to extend in the +Z direction. The first extension portion 704 may also be formed in only a portion of the entire region of the end portion on the -X direction side of the first arm portion 703 extending in the Y direction. Even in such a case, the first extension portion 704 can improve the bandwidth of the first antenna element 70 in the low frequency band.

[0067] The second antenna element 71 has a second feeding portion 711 , a second standing portion 712 , a second arm portion 713 , and a second extension portion 714 .

[0068] In this embodiment, the second antenna element 71 has the same characteristics as the first antenna element 70. Furthermore, the second antenna element 71 is formed so as to have a shape that is axisymmetric to the first antenna element 70 with respect to an axis parallel to the X direction in a plan view seen from the +Z direction, and therefore the second feeding portion 711, the second standing portion 712, the second arm 713, and the second extension portion 714 of the second antenna element 71 have the same characteristics as the corresponding first feeding portion 701, the first standing portion 702, the first arm 703, and the first extension portion 704 in the first antenna element 70, and therefore description thereof will be omitted.

[0069] <Housing> The housing 20 shown in FIG. 6 has a main body 200, holding portions 201a to 201d, and first convex portions 202a and 202b.

[0070] The main body 200 is a box-shaped member having an opening on the −Z direction side and a recess inside which the antenna unit 22 can be housed.

[0071] Each of the holding portions 201a to 201d is a portion that holds the planar antenna 60. The holding portion 201a is formed to extend in the −Z direction from the rear surface, which is the inner surface of the main body portion 200. The holding portion 201a also has a support portion 203a and a claw portion 204a.

[0072] The support portion 203a is a portion that supports the substrate 601 of the planar antenna 60. The support portion 203a is formed so as to extend from the rear surface of the main body portion 200 in the −Z direction.

[0073] The claw portion 204a is a portion that holds the substrate 601 of the planar antenna 60 together with the support portion 203a. The claw portion 204a is formed from a resin or the like and is elastically deformable. The claw portion 204a is formed to extend from the back surface of the main body portion 200 in the -Z direction so as to be longer than the support portion 203a. The claw portion 204a protrudes so that its tip overlaps the support portion 203a in a plan view seen from the -Z direction.

[0074] In this embodiment, each of the holding portions 201b to 201d has the same characteristics as the holding portion 201a. Therefore, the support portions 203b to 203d have the same characteristics as the support portion 203a, and the claw portions 204b to 204d have the same characteristics as the claw portion 204a, and therefore, the description thereof will be omitted.

[0075] As shown in FIG. 6 , the planar antenna 60 is disposed near the holders 201a-d so that the surface on which the dielectric 603 is disposed faces the back surface of the main body 200. The planar antenna 60 is then pushed in the +Z direction until the substrate 601 comes into contact with the support portions 203a-d of the holders 201a-d. At this time, because the claw portions 204a-d are elastically deformable, the substrate 601 climbs over the claw portions 204a-d and comes into contact with the support portions 203a-d, becoming sandwiched between the support portions 203a-d and the claw portions 204a-d. In this manner, the holders 201a-d hold the planar antenna 60. In this embodiment, the planar antenna 60 is further fixed to the housing 20 with screws.

[0076] The first protrusion 202a is a portion that sandwiches the first parasitic element 40 together with the second protrusion 211a (described later) of the cover 21. The first protrusion 202a is formed inside the main body 200 so as to protrude in the +X direction from the −X side surface of the main body 200 that extends in the Y direction.

[0077] The first protrusion 202b is a portion that sandwiches the second parasitic element 41 together with the second protrusion 211b (described later) of the cover 21. The first protrusion 202b is formed inside the main body 200 so as to protrude in the −X direction from the +X side surface of the main body 200 extending in the Y direction.

[0078] 1 is a member that closes the opening of the main body 200 of the housing 20. When the cover 21 is attached to the housing 20, it forms an accommodation space inside the housing 20 that accommodates the antenna unit 22. The cover 21 has a main body 210 and second protrusions 211a and 211b.

[0079] The main body 210 is a plate-like member that is larger than the opening of the main body 200 of the housing 20 .

[0080] The second protrusion 211a, together with the first protrusion 202a, sandwiches the first parasitic element 40. The second protrusion 211a is formed on the front surface of the main body 210 facing the +Z direction. The second protrusion 211a is formed so as to protrude from the front surface of the main body 210 in the +Z direction.

[0081] The second protrusion 211b, together with the first protrusion 202b, sandwiches the second parasitic element 41. The second protrusion 211b has the same characteristics as the second protrusion 211a, and therefore a description thereof will be omitted.

[0082] As shown in Fig. 7 , the first protrusion 202a and the second protrusion 211a sandwich the first parasitic element 40 from above and below. The first protrusion 202b and the second protrusion 211b sandwich the second parasitic element 41 from above and below. The enlarged view of Fig. 7 shows the second parasitic element 41 sandwiched between the first protrusion 202b and the second protrusion 211b from above and below. The first protrusion 202b presses the arm 411 of the second parasitic element 41 from above. Meanwhile, the second protrusion 211b supports the arm 411 from below. The first protrusion 202a and the second protrusion 211a sandwich the arm 401 from above and below, similar to the first protrusion 202b and the second protrusion 211b. As a result, the first parasitic element 40 and the second parasitic element 41 are fixed in the accommodation space, and can be kept in a stable state.

[0083] 1 , 6 and 7 , the tape 80 is a member that fixes the first antenna element 70 to the back surface of the main body 200 of the housing 20. The tape 80 is disposed between the front surface on the +Z side of the first arm 703 of the first antenna element 70 and the back surface of the main body 200 of the housing 20. The tape 80 is, for example, a double-sided tape having adhesive surfaces on both sides.

[0084] The tape 81 is a member that fixes the second antenna element 71 to the back surface of the main body 200 of the housing 20. The characteristics of the tape 81 are similar to those of the tape 80, and therefore a description thereof will be omitted. In this embodiment, the tapes 80 and 81 are used to fix the first antenna element 70, the second antenna element 71, and the housing 20, but an adhesive material, for example, may also be used.

[0085] 5 , in the first antenna element 70, the length La1 from the first feeding part 701 to the end of the first arm 703 in the +Y direction corresponds to the wavelength of the low frequency band (700 MHz to 900 MHz) of the first antenna element 70. The length of the ground plate 30 corresponding to the length La1 is La2, which is the sum of the length from the vicinity of the first feeding part 701 of the main body 300 to the end of the main body 300 in the +Y direction and the length of the extension part 321 in the Z direction.

[0086] Here, the length from the vicinity of the first feeding portion 701 of the main body 300 to the end of the main body 300 in the +Y direction is shorter than La1. Furthermore, the length of the main body 300 in the +Y direction cannot be made longer due to product constraints of the antenna device 10. Therefore, by forming the extension portion 321 to extend in the +Z direction from the end of the main body 300 in the +Y direction, the length La2 is made closer to the length La1. As will be described in detail later, this makes it possible to improve the characteristics of the first antenna element 70 for radio waves in the low frequency band.

[0087] Furthermore, in the antenna device 10 of this embodiment, the first parasitic element 40 is connected to the ground plate 30, and therefore the first parasitic element 40 functions as part of the ground plate 30. Here, the length La3 from the first feed portion 701 to the end of the arm portion 401 of the first parasitic element 40 in the +Y direction is shorter than the lengths La1 and La2. This improves the characteristics of the first antenna element 70 with respect to radio waves corresponding to the length La3. As will be described in detail later, the first antenna element 70 of this embodiment is provided with the first parasitic element 40, thereby enabling it to widen the band in the intermediate frequency range (1700 MHz to 2000 MHz), which is a band higher than the low frequency range.

[0088] As described above, the second antenna element 71, the extension 331, and the second parasitic element 41 are symmetrical about the central axis C that passes through the geometric center of the main body 300 and is parallel to the Y direction. Therefore, the second antenna element 71, the extension 331, and the second parasitic element 41 have similar features to the first antenna element 70, the extension 321, and the first parasitic element 40.

[0089] 4, the cable 51 is sandwiched between the wall portion 323 and the clamping portion 324. This fixes the position of the cable 51 on the front surface of the ground plate 30. Therefore, when removing the cable 51 from the ground plate 30, the cable 51 is pulled out along the wall portion 323. As a result, the cable 51 is easily removed from the ground plate 30. Note that the cable 51 sandwiched between the wall portion 333 and the clamping portion 334 has the same characteristics as the cable 51, and therefore a description thereof will be omitted.

[0090] <Frequency Characteristics> Fig. 8A is a diagram showing the VSWR frequency characteristics of each of the first antenna element 70 and the second antenna element 71. Fig. 8B is a diagram showing the VSWR frequency characteristics of each of the first antenna element 70 and the second antenna element 71, particularly from 600 MHz to 1000 MHz. In Figs. 8A and 8B, the horizontal axis represents frequency, and the vertical axis represents voltage standing wave ratio (VSWR). The value for the first antenna element 70 is shown by a solid line, and the value for the second antenna element 71 is shown by a dashed line.

[0091] 8A, the VSWR values ​​of the first antenna element 70 and the second antenna element 71 in the range from 1700 MHz to 2000 MHz are smaller than 4. This indicates that the first parasitic element 40 and the second parasitic element 41 described above widen the band in the intermediate frequency range.

[0092] 9 is a diagram showing the frequency characteristics of the correlation coefficient between the first antenna element 70 and the second antenna element 71. As shown in Fig. 9, the correlation coefficient between the first antenna element 70 and the second antenna element 71 is smaller than 0.5 in the range from 600 MHz to 5000 MHz. In other words, it can be seen that the isolation between the first antenna element 70 and the second antenna element 71 in the antenna device 10 is good.

[0093] Summary According to the present specification, there is provided an antenna device having the following aspects.

[0094] (Aspect 1) Aspect 1 includes a ground plate 30 having a shape having a longitudinal direction and a width direction, a first antenna element 70 having a first feeding portion 701, a first standing portion 702 formed to stand up from the first feeding portion 701, and a first arm portion 703 extending along the longitudinal direction from the first standing portion 702, and a first parasitic element 40 connected to a first end portion 302 in the width direction of the ground plate 30 and extending along the longitudinal direction of the ground plate 30, wherein the first end portion 302 is located near the first feeding portion 701 in a plan view.

[0095] According to the above-described aspect, it is possible to reduce the size of the antenna device while widening the frequency range of the antenna. Note that the Y direction in this embodiment corresponds to the "longitudinal direction," and the X direction corresponds to the "width direction." Furthermore, the ground plate 30 corresponds to the "ground element."

[0096] (Aspect 2) In aspect 2, the first antenna element 70 has a first extension 704 in the first arm 703 that extends from the end in the width direction toward the ground plate 30 side.

[0097] According to the above-described aspect, by extending the first extension portion 704 from the first arm portion 703, the low frequency band of the first antenna element 70 can be widened without widening the width of the first arm portion 703.

[0098] (Aspect 3) In aspect 3, there is provided a second antenna element 71 having a second power supply portion 711, a second standing portion 712 formed to stand up from the second power supply portion 711, and a second arm portion 713 extending longitudinally from the second standing portion 712, and a second parasitic element 41 connected to a second end portion 303 in the width direction of the ground plate 30 and extending longitudinally of the ground plate 30, wherein the second end portion 303 is located near the second power supply portion 711 in a plan view.

[0099] According to the above-described embodiment, the size of the antenna device 10 can be reduced while widening the frequency band supported by the two antenna elements 70 and 71.

[0100] (Example 4) In Example 4, the second antenna element 71 has a second extension 714 in the second arm 713 that extends from the end in the width direction toward the ground plate 30 side.

[0101] According to the above-described aspect, by extending the second extension portion 714 from the second arm portion 713, the low frequency band of the second antenna element 71 can be widened without widening the width of the second arm portion 713.

[0102] (Aspect 5) In aspect 5, the ground plate 30 has a main body portion 300 having a shape with a longitudinal direction and a width direction, and an extension portion 321 extending from the end of the main body portion 300 on the tip side of the first arm portion 703 in a direction intersecting the main body portion 300.

[0103] According to the above-described aspect, it is possible to increase the electrical length of the ground plate 30 without increasing the size of the ground plate 30 in a plan view. Note that the extensions 321 and 331 in this embodiment each correspond to a “third extension.”

[0104] (Aspect 6) Aspect 6 includes a planar antenna 60 located on the front side of the ground plate 30, and the ground plate 30 has an extension 322 extending in the width direction, and the extension 322 is located between the tip of the first arm 703 and the tip of the first parasitic element 40 in a planar view.

[0105] According to the above-described aspect, the area of ​​the ground plate 30 in a plan view can be increased, thereby improving the characteristics of the planar antenna 60. Note that each of the extensions 322 and 332 in this embodiment corresponds to a "fourth extension."

[0106] (Aspect 7) In aspect 7, the housing 20 is provided, and the housing 20 has a holder 201 for holding the planar antenna 60 inside the housing 20.

[0107] According to the above-described aspect, since the housing 20 has the holding portion 201, the planar antenna 60 can be easily held in the housing 20.

[0108] (Eighth Aspect) In an eighth aspect, a tape 80 is provided that is positioned between the front surface of the first antenna element 70 and the inner surface of the housing 20 and fixes the first antenna element 70 and the housing 20 together.

[0109] According to the above-described aspect, the first antenna element 70 is fixed to the housing 20 by the tape 80. Therefore, when fixing the first antenna element 70 to the housing 20, thermal welding or fixing with screws is not required, and therefore the first antenna element 70 can be easily fixed to the housing 20. Note that each of the tapes 80 and 81 in this embodiment corresponds to a "fixing member."

[0110] (Aspect 9) In aspect 9, the ground plate 30 has a wall portion 323 formed to rise from the ground plate 30 at the position where the extension portion 322 extends from the ground plate 30, and a clamping portion 324 that, together with the wall portion 323, clamps the cable 51 connected to the first antenna element 70.

[0111] According to the above-described embodiment, the cable 51 is sandwiched between the wall portion 323 and the clamping portion 324, so that the cable 51 can be easily removed.

[0112] (Aspect 10) In aspect 10, a cover 21 is provided that, together with the housing 20, forms an accommodation space for accommodating the ground plate 30, the first antenna element 70, and the first parasitic element 40. The housing 20 has a first convex portion 202 that extends toward the cover 21 on the inside of the housing 20, and the cover 21 has a second convex portion 211 that, together with the first convex portion 202, sandwiches the first parasitic element 40.

[0113] According to the above-described aspect, first parasitic element 40 is sandwiched between first protrusion 202 and second protrusion 211, so that first parasitic element 40 can be fixed within the accommodation space.

[0114] (Aspect 11) In aspect 11, a substrate 50 on which the first antenna element 70 is arranged is provided, and holes 500a, 500b, and 500c are formed in the substrate 50, and the ground plate 30 has protrusions 325a, 325b, and 325c that are inserted into the holes 500a, 500b, and 500c.

[0115] According to the above-described aspect, the position of the substrate 50 is determined by inserting the protrusions 325a, 325b, and 325c into the holes 500a, 500b, and 500c, respectively, thereby facilitating the positioning of the substrate 50. Furthermore, when the substrate 50 is correctly positioned, the protrusions 325a, 325b, and 325c protrude from the holes 500a, 500b, and 500c, facilitating visual confirmation.

[0116] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. Furthermore, the present invention may be modified or improved without departing from the spirit thereof, and the present invention includes equivalents thereof.

[0117] DESCRIPTION OF SYMBOLS 10 Antenna device, 20 Housing, 21 Cover, 30 Ground plate (ground element) 40 First parasitic element, 41 Second parasitic element, 50 Substrate, 60 Planar antenna 70 First antenna element, 71 Second antenna element, 80 Tape (fixing member) 201 Holding portion, 202a, 202b First protrusion, 211a, 211b Second protrusion 300 Main body, 321, 331 Extension portion (third extension portion), 322, 332 Extension portion (fourth extension portion), 323, 333 Wall portion 324, 334 Clamping portion, 325a, 325b, 325c Protrusion 500a, 500b, 500c Hole, 701 First feeding portion, 702 First standing portion 703 First arm portion, 704 First extension portion, 711: Second power supply portion, 712: Second standing portion, 713: Second arm portion, 714: Second extension portion

Claims

1. An antenna device comprising: a ground element having a shape with a longitudinal direction and a width direction; a first antenna element having a first power supply section, a first standing section formed to rise from the first power supply section, and a first arm section extending from the first standing section along the longitudinal direction; and a first parasitic element connected to a first end of the ground element in the width direction and extending along the longitudinal direction of the ground element, wherein the first end is located near the first power supply section in a planar view.

2. The antenna device according to claim 1, wherein the first antenna element has a first extension portion in the first arm that extends from the end in the width direction toward the ground element.

3. An antenna device as described in claim 1 or claim 2, comprising: a second antenna element having a second feed section, a second standing section formed to stand up from the second feed section, and a second arm section extending from the second standing section along the longitudinal direction; and a second parasitic element connected to a second end of the ground element in the width direction and extending along the longitudinal direction of the ground element, wherein the second end is located near the second feed section in a planar view.

4. The antenna device according to claim 3, wherein the second antenna element has a second extension portion in the second arm that extends from the end in the width direction toward the ground element.

5. An antenna device as claimed in any one of claims 1 to 4, wherein the ground element has: a main body portion having a shape having the longitudinal direction and the width direction; and a third extension portion extending from an end of the main body portion on the tip side of the first arm portion in a direction intersecting the main body portion.

6. An antenna device according to any one of claims 1 to 4, comprising a planar antenna located on the front side of the ground element, the ground element having a fourth extension portion extending in the width direction, the fourth extension portion being located between the tip of the first arm portion and the tip of the first parasitic element in a planar view.

7. The antenna device according to claim 6, comprising a housing, the housing having a holding portion for holding the planar antenna inside the housing.

8. The antenna device according to claim 7, further comprising a fixing member positioned between the front surface of the first antenna element and the inner surface of the housing, for fixing the first antenna element and the housing.

9. The antenna device described in claim 6, wherein the ground element has: a wall portion formed to rise from the ground element at a position where the fourth extension portion extends from the ground element; and a clamping portion that, together with the wall portion, clamps a cable connected to the first antenna element.

10. An antenna device as described in claim 7, further comprising a cover which, together with the housing, forms a storage space for accommodating the ground element, the first antenna element, and the first parasitic element, the housing having a first convex portion extending toward the cover on the inside of the housing, and the cover having a second convex portion which, together with the first convex portion, sandwiches the first parasitic element.

11. An antenna device according to claim 1 or claim 2, comprising a substrate on which the first antenna element is arranged, a hole formed in the substrate, and the ground element having a protrusion that is inserted into the hole.

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