Antenna and antenna device for vehicle

Abstract

An antenna is provided with a radiation plate having a radiation surface, a ground plate disposed on a side opposite to the radiation surface side of the radiation plate via a dielectric, and a passive element including a first passive conductor, a second passive conductor, and a third passive conductor, the first passive conductor, the second passive conductor, and the third passive conductor being configured so that the first passive conductor, the second passive conductor, and the third passive conductor are electrically connected to each other in a planar view of the radiation plate. The first passive conductor is disposed in a first direction with respect to the center of gravity of the radiant panel, the second passive conductor is disposed in a second direction opposite to the first direction with respect to the center of gravity of the radiant panel, and the third passive conductor is connected to the first passive conductor and the second passive conductor. The third passive conductor includes a portion that passes through a vicinity of a center of gravity of the radiant panel in a plan view of the radiant panel and extends in the first direction and the second direction.

Description

Technical Field

[0001] The present invention relates to an antenna and a vehicle antenna device. Background Art

[0002] In recent years, there has been a trend of expanding services using high-speed and large-capacity wireless communication systems that use microwave or millimeter wave bands, such as the transition from 4G LTE to 5G (sub6). The frequency band used tends to expand from the 3GHz band to the 5-6GHz band. In particular, in the field of vehicle antennas, as the level of autonomous driving improves, there is a tendency to install V2X (Vehicle to Everything) communication systems on vehicles that realize inter-vehicle communication and vehicle-to-road communication. For example, various safety-related external information can be obtained by transmitting and receiving narrowband radio waves in the 5.9GHz band. In this V2X communication system, an antenna (V2X antenna) that can transmit and receive vertically polarized radio waves in the frequency band (5.8GHz band (Japan) / 5.9GHz band (Europe and the United States) that meets the V2X communication standard with the desired gain is required.

[0003] The V2X antenna needs to be able to ensure the directivity of gain within a range of 180° from the vehicle's traveling direction (front or rear) to the ±90° left and right directions in the horizontal plane. As such a V2X antenna, in order to improve not only the directivity in the normal direction of the patch surface of the radiating element but also the directivity in the left and right directions (the vehicle width direction) of the patch surface, a patch antenna having passive elements on both sides of the radiating element is known (for example, see Patent Documents 1, 2, and 3). Prior art literature Patent Literature

[0004] Patent Document 1: Japanese Patent Application Publication No. 2019-075644 Patent Document 2: International Publication No. 2019 / 163521 Patent Document 3: International Publication No. 2019 / 208453 Summary of the invention Technical problem to be solved by the invention

[0005] However, since the passive elements on both sides of the radiating element are spaced apart from each other, their positions may deviate from each other. For example, even if one passive element is positioned correctly, if the other passive element deviates from the correct position, the directivity level of the entire antenna may deviate.

[0006] The present invention provides an antenna with improved arrangement accuracy of passive conductors arranged on both sides of a radiation plate and a vehicle antenna device having the antenna. Solution

[0007] A first aspect of the present disclosure provides an antenna including a radiation plate, a ground plate, and a passive element. The radiation plate has a radiation surface. The ground plate is arranged on the side of the radiation plate opposite to the radiation surface side via a dielectric. The passive element comprises a first passive conductor, a second passive conductor and a third passive conductor. In a top view of the radiation board, the first passive conductor is arranged in a first direction with the center of gravity of the radiation board as a reference, the second passive conductor is arranged in a second direction opposite to the first direction with the center of gravity of the radiation board as a reference, and the third passive conductor is connected to the first passive conductor and the second passive conductor. The third passive conductor includes a portion that passes through the vicinity of the center of gravity of the radiation board in a top view of the radiation board and extends along the first direction and the second direction.

[0008] The second mode is that in the antenna of the first mode, when the direction orthogonal to the first direction is set as the third direction, the width of the third passive conductor in the third direction is set as W, and the length of the first passive conductor or the second passive conductor in the third direction is set as L, W / L can satisfy W / L≦0.50.

[0009] A third aspect is the antenna of the second aspect, wherein an end of the third parasitic conductor may be connected to the first parasitic conductor or the second parasitic conductor at a position in a range of 30% to 70% inclusive when the length L is 100%.

[0010] The fourth mode is an antenna of any one of the first mode to the third mode, in which, in a top view of the radiation plate, a direction orthogonal to the first direction is set as a third direction, a direction opposite to the third direction is set as a fourth direction, the third direction relative to a reference line passing through the center of gravity of the radiation plate and parallel to the first direction is set as positive, the fourth direction relative to the reference line is set as negative, and the length of the radiation surface in the third direction is set as D. In a plan view of the radiation plate, the third passive conductor may overlap a range from the reference line to ±0.30×D.

[0011] A fifth aspect is the antenna according to any one of the first to fourth aspects, wherein the second parasitic conductor may have the same shape as the first parasitic conductor in a plan view of the radiation plate.

[0012] A sixth aspect is an antenna according to any one of the first to fifth aspects, wherein the outer edge of the radiation plate may be a substantially quadrilateral having a pair of sides parallel to the first direction and a pair of sides parallel to a direction orthogonal to the first direction when viewed from above the radiation plate. An extension conductor, i.e., a power supply line, connected to a power supply point of the radiation plate may be arranged on a plane parallel to the radiation surface.

[0013] A seventh aspect is the antenna according to any one of the first to sixth aspects, wherein at least one of the first parasitic conductor and the second parasitic conductor may not overlap with the radiation plate in a plan view of the radiation plate.

[0014] An eighth aspect is the antenna according to any one of the first to seventh aspects, wherein at least one of the first parasitic conductor and the second parasitic conductor may not overlap with the ground plate in a plan view of the radiation plate.

[0015] A ninth aspect is the antenna according to any one of the first to eighth aspects, wherein the parasitic element may be point-symmetrical in shape.

[0016] A tenth aspect is the antenna of the ninth aspect, wherein the center of gravity of the passive element may overlap with the center of gravity of the radiation plate in a top view of the radiation plate.

[0017] An eleventh aspect is the antenna according to any one of the first to tenth aspects, wherein the first parasitic conductor and the second parasitic conductor may be arranged on a side opposite to the ground plate side with respect to the radiation plate.

[0018] A twelfth aspect is the antenna according to any one of the first to eleventh aspects, wherein the first parasitic conductor and the second parasitic conductor may be arranged on a plane different from the radiation surface.

[0019] A thirteenth aspect is the antenna according to any one of the first to twelfth aspects, wherein the third parasitic conductor may have a bridge shape extending in a direction different from a direction parallel to the radiation surface and crossing the radiation surface.

[0020] A fourteenth aspect is the antenna of any one of the first to thirteenth aspects, wherein the first parasitic conductor and the second parasitic conductor may be arranged on the same plane as the radiation surface without overlapping the radiation plate in a plan view of the radiation plate.

[0021] A fifteenth aspect is the antenna according to any one of the first to fourteenth aspects, further comprising a connector for connection to a coaxial cable, the connector being disposed on the side opposite to the radiation surface with respect to the ground plate.

[0022] A sixteenth aspect is the antenna according to any one of the first to fifteenth aspects, wherein the third parasitic conductor can be fixed by a dielectric.

[0023] The seventeenth aspect is the antenna according to the sixteenth aspect, wherein the first parasitic conductor and the second parasitic conductor may be in contact with air except for a portion connected to the third parasitic conductor.

[0024] Furthermore, one aspect of the present invention provides a vehicle antenna device including the antenna.

[0025] An eighteenth aspect is a vehicle antenna device comprising a vehicle window glass and the antenna according to any one of the first to seventeenth aspects. The radiation surface of the antenna is arranged to face the window glass, The radiation surface is inclined at an angle within ±15° relative to a vertical plane that is at right angles to the horizontal plane.

[0026] The nineteenth aspect is that in the vehicle antenna device of the eighteenth aspect, on the radiation plane, a straight line connecting the center of gravity of the radiation plate and the power supply point of the radiation plate can be inclined at an angle within ±15° relative to a vertical plane perpendicular to the horizontal plane. The frequency band of the radio wave received by the antenna can include a 5.8 GHz band or a 5.9 GHz band.

[0027] The twentieth aspect is the vehicle antenna device of the eighteenth aspect or the nineteenth aspect, wherein the antenna may be a V2X antenna. Effects of the Invention

[0028] According to one aspect of the present invention, it is possible to provide an antenna having improved arrangement accuracy of parasitic conductors arranged on both sides of a radiation plate and a vehicle antenna device including the antenna. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a partially enlarged view illustrating a vehicle antenna device including the antenna according to the present embodiment from a side view. Figure 2 The diagram shows the antenna of this embodiment in a plan view. Figure 3 It is a longitudinal sectional view of the antenna according to this embodiment. Figure 4 It is a top view of a modified example of the radiation plate. Figure 5 It is a perspective view of a modified example of a passive component. Figure 6 This is a perspective view of an antenna with a connector. Figure 7 This is a diagram showing an example of simulation results of antenna directivity. DETAILED DESCRIPTION

[0030] The present embodiment is described below with reference to the accompanying drawings. In addition, for ease of understanding, the scales of the various parts in the accompanying drawings are sometimes different from the actual ones. Parallel, right angles, orthogonal, horizontal, vertical, up and down, left and right directions, as well as the same and equal terms allow deviations to the extent that the functions and effects of the embodiments are not impaired. The shape of the corner is not limited to a right angle, and can also be arched with rounded corners. Overlapping includes the meaning of partial overlap. The X-axis direction, the Y-axis direction, and the Z-axis direction respectively represent the direction parallel to the X-axis, the direction parallel to the Y-axis, and the direction parallel to the Z-axis. The X-axis direction, the Y-axis direction, and the Z-axis direction are orthogonal to each other. The XY plane, the YZ plane, and the ZX plane respectively represent an imaginary plane parallel to the X-axis direction and the Y-axis direction, an imaginary plane parallel to the Y-axis direction and the Z-axis direction, and an imaginary plane parallel to the Z-axis direction and the X-axis direction.

[0031] The antenna of this embodiment can be applied to, for example, V2X communication systems, fifth-generation mobile communication systems (so-called 5G), vehicle-mounted radar systems, etc., but the applicable systems are not limited to these. As an example of a V2X communication system, there is an ETC system. The antenna of each embodiment of the present disclosure is suitable for use in a frequency band below 6 GHz (sub6) in the frequency band used by 5G, and is suitable for transmitting and receiving (one or both of transmitting and receiving) radio waves such as 5.8 GHz band or 5.9 GHz band. However, the antenna of this embodiment is not limited to the frequency band used by 5G (above 3.3 GHz), and can also be used in 4G LTE or millimeter wave bands (30 GHz to 300 GHz) or microwaves.

[0032] Examples of vehicle window glass to which the present embodiment is applied include a windshield glass mounted on the front of a vehicle, a rear window glass mounted on the rear of a vehicle, and side window glass mounted on the sides of a vehicle.

[0033] Figure 1 This is a partially enlarged view illustrating a vehicle antenna device including the antenna according to the present embodiment from a side view. Figure 1 The antenna device 101 shown is an example of a vehicle antenna device, and includes a window glass 70 and an antenna 111 .

[0034] The window glass 70 is a vehicle window glass, for example, a windshield installed on the front side of the vehicle 80. The window glass 70 is attached to a window frame on the front side of the vehicle 80 at a predetermined installation angle θ relative to a horizontal plane. In this example, the horizontal plane is parallel to the ZX plane.

[0035] The antenna 111 is installed on the inner side of the window glass 70 via a frame or other components, for example, it is installed near the central part of the upper area of ​​the window glass 70. The number of antennas 111 installed on the window glass 70 can be one or more. The antenna 111 is used, for example, as a V2X antenna for transmitting and receiving radio waves including the 5.8 GHz band or the 5.9 GHz band. The antenna 111 includes a structure of a patch antenna, and the patch antenna includes a radiation plate 20 with a radiation surface 29 as a patch surface. In this example, the antenna 111 includes a ground plate 10, a radiation plate 20, a dielectric substrate 60 and a passive element 50. The ground plate 10, the radiation plate 20, the dielectric substrate 60 and the passive element 50 can be housed in a frame such as an outer frame of the antenna 111, for example, fixed to the inside of the frame. The frame such as the outer frame is a component with a dielectric such as resin as a main component.

[0036] The ground plane 10 is generally a planar conductive layer whose surface is parallel to the XY plane, and functions as a ground for the antenna 111. The ground plane 10 is a plate-shaped or film-shaped conductor. As the material of the conductor used for the ground plane 10, for example, silver, copper, etc. can be cited, but the material is not limited thereto. In addition, the shape of the ground plane 10 is, for example, a square, but it can also be a polygon other than a square, and can also be other shapes such as a circle.

[0037] In addition, the “plate-like or film-like” is not limited to a two-dimensional shape, but may include a three-dimensional shape, such as a convex shape, a concave shape, or a wavy shape. The “plate-like or film-like” is not limited to the shape of the ground plate 10, but may also be applied to the shape of the radiation plate 20, the dielectric substrate 60, or the passive element 50.

[0038] The radiation plate 20 is a plate-shaped or film-shaped conductor arranged opposite to the ground plate 10 in the Z-axis direction, and is generally designed to be narrower than the ground plate 10 in a top view. The radiation plate 20 is a planar conductive layer whose surface is parallel to the XY plane, and functions as a radiation element of the antenna 111. As the material of the conductor used for the radiation plate 20, for example, silver, copper, etc. can be cited, but the material is not limited thereto. In addition, the shape of the radiation plate 20 is, for example, a square, but it can also be a rectangle, a polygon other than a square, or other shapes such as a circle. The radiation plate 20 has a radiation surface 29 facing the normal direction of the ground plate 10 (in this example, the positive side of the Z-axis direction).

[0039] The radiation plate 20 is arranged to be separated from the ground plate 10. The medium between the ground plate 10 and the radiation plate 20 includes at least one of space and a dielectric substrate. The antenna 111 shows a case where the medium between the ground plate 10 and the radiation plate 20 is composed only of the dielectric substrate 60. In addition, when the medium is space (air), the radiation plate 20, the ground plate 10 and the passive element 50 can be fixed by a frame not shown as needed.

[0040] The dielectric substrate 60 is a plate-shaped or film-shaped dielectric layer having a dielectric as a main component. The dielectric substrate 60 has a first surface 61 and a second surface 62 on the opposite side to the first surface 61. The surfaces 61 and 62 are parallel to the XY plane. The radiation plate 20 is provided on the surface 61 which is one surface of the dielectric substrate 60, and the ground plate 10 is provided on the surface 62 which is the other surface of the dielectric substrate 60. The ground plate 10 is arranged on the side of the radiation plate 20 opposite to the radiation surface 29 side via the dielectric substrate 60.

[0041] The dielectric substrate 60 may be, for example, a dielectric substrate such as a glass epoxy substrate, or a dielectric sheet. The dielectric material used for the dielectric substrate 60 may be, for example, glass such as quartz glass, ceramics, fluorine resins such as polytetrafluoroethylene, liquid crystal polymers, cycloolefin polymers, etc., but the material is not limited thereto.

[0042] Figure 2 The figure shows the antenna of this embodiment from a top view. The top view refers to the viewpoint from the positive side in the Z-axis direction. When the antenna 111 is mounted on the vehicle, Figure 2 A front view of the antenna 111 is shown. Figure 3 It is a longitudinal sectional view of the antenna according to this embodiment. Figure 3 It is a cross-sectional view taken along the YZ plane passing through the center of gravity 21 of the radiation plate 20. The power supply unit 30 and the radiation plate 20 are connected via a connection conductor 40 passing through the inside of the dielectric substrate 60 in the Z-axis direction.

[0043] The power supply unit 30 is a part that supplies power in a contact or non-contact manner, and is a part to which one end of a power supply line (not shown) is connected or in close proximity. Specific examples of the power supply line include transmission lines such as coaxial cables, microstrip lines, strip lines, coplanar lines, and slot lines. The other end of the power supply line is connected to a communication device that communicates with the outside of the vehicle using an antenna 111. The power supply unit 30 is located on the side where the ground plate 10 is arranged relative to the radiation plate 20.

[0044] Figure 3 , the connection conductor 40 is not in contact with the ground plate 10. One end of the connection conductor 40 is connected to the power supply portion 30, and the other end is connected to the radiation plate 20 at the power supply point 22. The power supply point 22 is offset from the center of gravity 21 of the radiation plate 20, and in the case shown in the figure, it is located on the negative side of the Y-axis direction relative to the center of gravity 21. The power supply point 22 overlaps with a reference line 28 passing through the center of gravity 21 and parallel to the Y-axis direction in a top view of the radiation plate 20. In the case where the radiation plate 20 is a symmetrical figure such as a square, the center of gravity 21 is equivalent to the center of the symmetrical figure. In addition, the antenna 111 can transmit and receive polarized waves in the direction of the straight line connecting the center of gravity 21 and the power supply point 22, especially in a direction like Figure 1When the antenna 111 is arranged in that way, vertically polarized waves can be transmitted and received, and it can be suitably used as a V2X antenna.

[0045] Specific examples of the connection conductor 40 include a conductor formed by penetrating the inside of the through hole of the dielectric substrate 60 in the Z-axis direction, a core wire of a coaxial cable, a conductor pin formed in a pin shape, etc., but the connection conductor 40 is not limited to these. In addition, when the dielectric between the ground plate 10 and the radiation plate 20 includes a space, specific examples of the connection conductor 40 include a core wire of a coaxial cable or a conductor pin, etc., but the connection conductor 40 is not limited to these.

[0046] From the perspective of the radiation plate 20 side relative to the ground plate 10, the center of gravity 21 of the radiation plate 20 overlaps with the center of gravity 11 of the ground plate 10, which is preferable from the perspective of improving the antenna gain of the antenna 111 in the direction from the ground plate 10 side toward the radiation plate 20 side. In this example, the perspective from the radiation plate 20 side relative to the ground plate 10 means the viewpoint from the positive side in the Z-axis direction, and the direction from the ground plate 10 side toward the radiation plate 20 side means the direction toward the positive side in the Z-axis direction.

[0047] The passive element 50 is disposed apart from the radiation plate 20 and is located on the positive side in the Z-axis direction of the radiation surface 29. The passive element 50 is a passive conductor that is not connected to the power supply unit 30.

[0048] Figure 2 In the embodiment, the passive element 50 includes a first passive conductor 51, a second passive conductor 52, and a third passive conductor 53. The first passive conductor 51 is a portion arranged in a first direction Xp (in this example, the positive side of the X-axis direction) with the center of gravity 21 of the radiation board 20 as a reference in a top view of the radiation board 20. The second passive conductor 52 is a portion arranged in a second direction Xn (in this example, the negative side of the X-axis direction) opposite to the first direction Xp with the center of gravity 21 of the radiation board 20 as a reference in a top view of the radiation board 20. The third passive conductor 53 is a portion connected to the first passive conductor 51 and the second passive conductor 52.

[0049] In a top view of the radiation plate 20, the first passive conductor 51 is arranged in the first direction Xp with the center of gravity 21 as a reference, and the second passive conductor 52 is arranged in the second direction Xn with the center of gravity 21 as a reference. By arranging the first passive conductor 51 and the second passive conductor 52 in this way, when the antenna 111 is mounted on the vehicle, they are located at positions spaced apart from each other on both sides of the radiation plate 20 in the vehicle width direction (in the case of the figure, the X-axis direction of the vehicle width direction). Since the first passive conductor 51 and the second passive conductor 52 are located at positions spaced apart from each other on both sides of the radiation plate 20 in the vehicle width direction, the antenna gain of the antenna 111 in the vehicle width direction in the horizontal plane is improved.

[0050] Assuming that the antenna 111 is arranged facing the windshield but does not include the passive element 50 (the first passive conductor 51, the second passive conductor 52, and the third passive conductor 53), in the horizontal plane, the antenna gain in the direction of travel (of the vehicle) perpendicular to the vehicle width direction is large, while the antenna gain in the vehicle width direction is relatively small. However, by providing the antenna 111 with the first passive conductor 51 and the second passive conductor 52, in the horizontal plane, the antenna gain in the direction of travel is appropriately dispersed in the antenna gain in the vehicle width direction. As a result, it is possible to obtain directivity that ensures the antenna gain within a range of 180° from the vehicle's direction of travel (front or rear) to the ±90° left and right directions in the horizontal plane.

[0051] In addition, since the first passive conductor 51 and the second passive conductor 52 are connected by the third passive conductor 53, the respective configuration positions of the first passive conductor 51 and the second passive conductor 52 are not easily deviated. Thus, the positional relationship between the first passive conductor 51 and the second passive conductor 52, the positional relationship between the first passive conductor 51 and the radiation plate 20, and the positional relationship between the second passive conductor 52 and the radiation plate 20 are not easily deviated. Therefore, the respective configuration accuracy of the first passive conductor 51 and the second passive conductor 52 of the antenna 111 is improved, thereby suppressing deviation in directivity that ensures antenna gain within a range of 180° from the vehicle's traveling direction (front or rear) to at least ±90° to the left and right in the horizontal plane.

[0052] The passive element 50 (the first passive conductor 51, the second passive conductor 52, and the third passive conductor 53) may be composed of one member or a plurality of members. In addition, part or all of the passive element 50 (the first passive conductor 51, the second passive conductor 52, and the third passive conductor 53) may be formed by stamping or the like from a metal plate such as a steel plate, or may be formed by molding, but it is preferred that all of them are formed in one piece because productivity is improved.

[0053] In addition, the third passive conductor 53 includes a portion extending along the first direction Xp and the second direction Xn (i.e., the direction parallel to the ZX plane) passing through the vicinity of the center of gravity 21 of the radiation plate 20 in a top view of the radiation plate 20. The vicinity of the center of gravity 21 refers to a portion at a distance from the center of gravity 21, and is a range close to the center of gravity 21 to a degree that does not impair the function and effect of the present embodiment. On the other hand, since the power supply point 22 is offset from the center of gravity 21 in the Y-axis direction on the radiation surface 29, the antenna 111 transmits and receives the electric wave of the linear polarized wave whose polarization wave plane is parallel to the YZ plane through the radiation surface 29. Therefore, even if the third passive conductor 53 includes a portion extending along the first direction Xp and the second direction Xn (the direction parallel to the ZX plane), it will hardly affect the transmission and reception of the electric wave of the linear polarized wave whose polarization wave plane is parallel to the YZ plane. That is, the third parasitic conductor 53 can suppress a decrease in the antenna gain of the antenna 111 when the polarization wave plane is a linearly polarized wave parallel to the YZ plane (for example, a vertically polarized wave when the ZX plane is parallel to the horizontal plane).

[0054] The third parasitic conductor 53 can be fixed by, for example, a fixing member mainly composed of a dielectric by press-fitting or the like. This can suppress a reduction in antenna gain and a deviation in directivity of the antenna 111 caused by a positional deviation of the third parasitic conductor 53. As a specific example of the fixing member, a snap fit formed inside a frame such as an outer frame of the antenna 111 can be cited.

[0055] When the third passive conductor 53 is fixed by a dielectric such as the above-mentioned fixing member, the first passive conductor 51 and the second passive conductor 52 may include an exposed portion in contact with the air in addition to the portion connected to the third passive conductor 53. Thereby, compared with a form in which the first passive conductor 51 and the second passive conductor 52 are in contact with a dielectric having a higher relative dielectric constant than air, the antenna gain near the X-axis direction in the ZX plane is improved. For example, the exposed portion is exposed so as to be visible from the outside of the outer frame of the antenna 111.

[0056] In addition, the radiation surface 29 is preferably inclined at an angle within ±15° relative to the vertical plane at right angles to the horizontal plane. Thereby, the antenna gain of the antenna 111 in the direction parallel to the horizontal plane is improved. In particular, on the radiation surface 29, when the straight line (reference line 28) connecting the center of gravity 21 and the power supply point 22 is inclined at an angle within ±15° relative to the vertical plane at right angles to the horizontal plane, the antenna gain of the antenna 111 in the case of vertically polarized waves is improved. On the other hand, if the radiation surface 29 is inclined at an angle exceeding ±15° relative to the vertical plane at right angles to the horizontal plane, the balance of the antenna gain in the direction parallel to the horizontal plane may be destroyed, that is, the difference between the gain in the direction of travel of the vehicle and the gain in the vehicle width direction may increase.

[0057] From the perspective of improving the antenna gain in the direction parallel to the horizontal plane, the radiating surface 29 is preferably inclined at an angle within ±10°, more preferably within ±5°, relative to a vertical plane perpendicular to the horizontal plane.

[0058] In a top view of the radiation plate 20, a direction perpendicular to the first direction Xp is set as a third direction Yp (in this example, the positive side of the Y-axis direction), and a direction opposite to the third direction Yp is set as a fourth direction Yn (in this example, the negative side of the Y-axis direction). Furthermore, the third direction Yp relative to a reference line 27 passing through the center of gravity 21 and parallel to the first direction Xp is set as positive, the fourth direction Yn relative to the reference line 27 is set as negative, and the length of the radiation surface 29 in the third direction is set as D.

[0059] At this time, when the third parasitic conductor 53 overlaps the range from the reference line 27 to ±0.30×D in the top view of the radiation plate 20, the antenna gain of the antenna 111 can be ensured in the case of a linearly polarized electric wave whose polarization wave plane is parallel to the YZ plane. In terms of ensuring the antenna gain of the antenna 111, the third parasitic conductor 53 preferably overlaps the range from the reference line 27 to ±0.25×D in the top view of the radiation plate 20, and more preferably overlaps the range from the reference line 27 to ±0.20×D. In terms of ensuring the antenna gain of the antenna 111, the third parasitic conductor 53 more preferably overlaps the range from the reference line 27 to ±0.15×D in the top view of the radiation plate 20, particularly preferably overlaps the range from the reference line 27 to ±0.10×D, and most preferably overlaps the range from the reference line 27 to ±0.05×D.

[0060] In the top view of the radiation board 20, the width of the third passive conductor 53 in the third direction Yp is set to W, and the length of the first passive conductor 51 or the second passive conductor 52 in the third direction Yp is set to L. At this time, when W / L satisfies W / L≦0.50 When the polarization wave plane is parallel to the YZ plane, the antenna gain of the antenna 111 can be ensured. From the perspective of ensuring the antenna gain of the antenna 111, W / L preferably satisfies W / L≦0.40, more preferably satisfies W / L≦0.30, further preferably satisfies W / L≦0.20, and particularly preferably satisfies W / L≦0.15.

[0061] The lower limit of W is not particularly limited, but from the perspective of maintaining stable rigidity, it can be, for example, above 0.1 mm, above 0.3 mm, above 0.5 mm, or above 1.0 mm. In addition, the lower limit of W / L is not particularly limited, and can be above 0.01, above 0.02, or above 0.03.

[0062] In addition, the third passive conductor 53 may have at least one of a portion where the width W between the two ends gradually increases and a portion where the width W gradually decreases toward the extension direction (length direction). Furthermore, the extension direction between the two ends of the third passive conductor 53, more specifically, the line formed by connecting the centers of the width W is not limited to a straight extension shape, and may have a partially curved portion or a partially wavy portion.

[0063] When the end of the third parasitic conductor 53 is connected to the first parasitic conductor 51 or the second parasitic conductor 52 at a position in the range of 30% to 70% when the length L is 100%, the antenna gain of the antenna 111 can be ensured in the case of a linearly polarized electric wave whose polarization plane is parallel to the YZ plane. In terms of ensuring the antenna gain of the antenna 111, the end of the third parasitic conductor 53 is preferably connected to the first parasitic conductor 51 or the second parasitic conductor 52 at a position in the range of 35% to 65%, and preferably connected to the first parasitic conductor 51 or the second parasitic conductor 52 at a position in the range of 40% to 60%. In addition, when the third parasitic conductor 53 is within the above range, the extension direction (length direction) may be arranged to be inclined with respect to the X-axis. When arranged to be inclined with respect to the X-axis, the third parasitic conductor 53 is preferably arranged to overlap with the center of gravity 21 of the radiation plate 20 when the radiation plate 20 is viewed from above. Furthermore, when the third parasitic conductor 53 is within the above range, the extending direction (length direction) of the third parasitic conductor 53 may be arranged substantially parallel to the X-axis, and is preferably arranged parallel to the X-axis.

[0064] When the second passive conductor 52 has the same shape as the first passive conductor 51 in a top view of the radiation plate 20, the antenna gain of the antenna 111 can be ensured in the case of a linearly polarized electric wave whose polarization wave plane is parallel to the YZ plane. However, when the radiation plate 20 is viewed from a top view, the second passive conductor 52 may not have the same shape as the first passive conductor 51.

[0065] A part or the whole of at least one of the first parasitic conductor 51 and the second parasitic conductor 52 may or may not overlap with the radiation plate 20 in a plan view of the radiation plate 20 . Figure 2 The case where both the first parasitic conductor 51 and the second parasitic conductor 52 overlap with the radiation plate 20 in a plan view of the radiation plate 20 is illustrated.

[0066] At least one of the first parasitic conductor 51 and the second parasitic conductor 52 may or may not overlap with the ground plate 10 in a plan view of the radiation plate 20 . Figure 2The example shows a case where both the first passive conductor 51 and the second passive conductor 52 overlap with the ground plate 10 in a plan view of the radiation plate 20. The configuration where both the first passive conductor 51 and the second passive conductor 52 do not overlap with the ground plate 10 means that the first passive conductor 51 and the second passive conductor 52 are arranged outside the outer edge of the ground plate 10.

[0067] Passive element 50 has a point-symmetrical shape with centroid 54 as the center of symmetry. Centroid 54 indicates the center of gravity of passive element 50. Figure 2 An H-shaped shape that is point-symmetrical with the center of gravity 54 as the center of symmetry is illustrated. However, the passive element 50 may also be a shape that is not point-symmetrical. The so-called point-symmetrical shape includes, for example, a shape in which the lengths L of the first passive conductor 51 and the second passive conductor 52 are different, a shape in which the first passive conductor 51 and the second passive conductor 52 are at different distances from the center of the third passive conductor 53, and the like. In addition, in the case where the passive element 50 is a point-symmetrical (flat) shape of an H-shape, it is preferred that the length direction of the first passive conductor 51 is parallel to the length direction of the second passive conductor 52, and the length direction of the third passive conductor 53 is orthogonal to the length directions of the first passive conductor 51 and the second passive conductor 52. For example, in the case where the passive element 50 is such an H-shaped shape, it is not necessary to align the front and back sides or ( Figure 2 The rotation position on the XY plane in the image is managed to improve productivity.

[0068] When the center of gravity 54 of the passive element 50 overlaps with the center of gravity 21 of the radiation plate 20 in a top view of the radiation plate 20, the antenna gain of the antenna 111 can be ensured in the case of a linearly polarized radio wave whose polarization plane is parallel to the YZ plane. However, the center of gravity 54 may not overlap with the center of gravity 21.

[0069] The outer edge of the radiation plate 20 is a substantially quadrilateral having a pair of sides 25, 26 parallel to the first direction Xp and a pair of sides 23, 24 parallel to a direction orthogonal to the first direction Xp when viewed from above the radiation plate 20. Figure 4 As shown in the example, the outer edge of the radiation plate 20 may be defined as a substantially quadrilateral as long as it is a quadrilateral as a whole, even if a part of the side is notched or the like.

[0070] Figure 4 It is a top view of a modified example of the radiation plate. Figure 4 The edge 25 of the radiation plate 20 is provided with a cutout. Figure 4 The power supply line 31 is shown extending so as to cross the side 25 . The power supply line 31 is an extended conductor connected to the power supply point 22 , and is arranged on a plane parallel to the radiation surface 29 . Figure 4In the embodiment, the power supply line 31 is formed on the same surface as the radiation surface 29. Furthermore, the power supply line 31 extends from the power supply line end 33 to the back side of the dielectric substrate 60 and is connected to a transmission line such as a coaxial cable (not shown).

[0071] Figure 1 to Figure 3 The case where the first passive conductor 51 and the second passive conductor 52 are arranged on the side opposite to the ground plate 10 side with respect to the radiation plate 20 is illustrated. Figure 1 to Figure 3 The first parasitic conductor 51 and the second parasitic conductor 52 are arranged on an XY plane different from the XY plane on which the radiation surface 29 is arranged. However, the first parasitic conductor 51 and the second parasitic conductor 52 may be arranged on the same XY plane as the radiation surface 29 (for example, the first surface 61 of the dielectric substrate 60).

[0072] Figure 5 : is a perspective view of a modified example of a passive element. It illustrates a case where the first passive conductor 51 and the second passive conductor 52 are arranged on the same XY plane (the first surface 61 of the dielectric substrate 60) as the radiation surface 29 without overlapping with the radiation plate 20 when viewed from above. Figure 5 The third parasitic conductor 53 is exemplified as extending in a direction different from the direction parallel to the radiation surface 29 and having a bridge shape crossing the radiation surface 29 so as to form a gap between the third parasitic conductor 53 and the radiation surface 29. The third parasitic conductor 53 overlaps the radiation surface 29 in the XY plane.

[0073] Figure 6 1 is a perspective view of an antenna having a connector. The antenna 111 may include a connector 55 for connecting to the coaxial cable 32, which is arranged on the side opposite to the radiation surface 29 relative to the ground plate 10. The connector 55 is a female connector in which a female connector is inserted into a male connector provided at the front end of the coaxial cable 32. By inserting the male connector provided at the front end of the coaxial cable 32 into the connector 55, the internal conductor (signal line) of the coaxial cable 32 is electrically connected to the power supply point 22 of the radiation surface 29, and the external conductor (shield) of the coaxial cable 32 is electrically connected to the ground plate 10. In particular, when the antenna 111 includes the connector 55, as shown in FIG. Figure 4 As in the modified example of the radiation plate 20 shown in the figure, the core wire tip of the coaxial cable 32 can be arranged near the rear side of the power supply line end 33 , so it is easy to ensure a space for fixing the connector 55 on the rear side of the radiation plate 20 .

[0074] Figure 7 This is a diagram showing an example of simulation results of directivity on the ZX plane of the antenna 111 under the condition of vertically polarized waves with a frequency of 5.88 GHz. "Without third passive conductor" represents an embodiment of the antenna 111, and "without third passive conductor" represents a structure after removing the third passive conductor 53 from the antenna 111 (comparative example). Figure 7 In FIG. 1 , the direction of 90° is the normal direction of the radiation surface 29 , which is the direction in which the vehicle is assumed to be traveling.

[0075] like Figure 7 As shown, the result that the directivity pattern hardly changes is obtained regardless of whether the third passive conductor 53 is present or not.

[0076] In addition, Figure 7 During the simulation, the conditions of each part of the antenna 111 are as follows: Ground plate 10: 19 mm long x 19 mm wide Dielectric substrate 60: 20 mm in length × 20 mm in width Radiating surface 29: 12.7 mm long x 12.7 mm wide Length L of the first passive conductor 51 and the second passive conductor 52: 14 mm The third passive conductor 53 has a width W of 1.5 mm. The third passive conductor 53 length: 27 mm Position of the power supply point 22: offset 2 mm from the center of gravity 21 in the Y-axis direction. Both ends of the third passive conductor 53 are connected to the first passive conductor 51 and the second passive conductor 52 at positions of 50% of their respective lengths L, and the center of the width W of the third passive conductor 53 is arranged to overlap with the center of gravity of the radiation surface 29. Furthermore, under this condition, in a plan view of the radiation plate 20, the first passive conductor 51 and the second passive conductor 52 are arranged so as not to overlap with the radiation plate 20 and the ground plate 10.

[0077] The embodiments are described above, but the above embodiments are disclosed only as examples, and the above embodiments do not limit the present invention. The above embodiments can be implemented in various other ways, and various combinations, omissions, substitutions, changes, etc. can be performed without departing from the scope of the invention. These embodiments and their variations are included in the scope or spirit of the invention, and are included in the invention described in the claims and their equivalents.

[0078] For example, the antenna is not limited to the case where the radiation surface is arranged to face the vehicle window glass, and may be installed on a vehicle surface such as a roof of the vehicle.

[0079] The present international application claims the benefit of priority based on Japanese Patent Application No. 2022-109313 filed on July 6, 2022, the entire contents of which are incorporated herein by reference. Explanation of symbols

[0080] 10 Ground plate 11 Center of Gravity 20 Radiant Panels 21 Center of gravity 22 power supply points 23~26 sides 27,28 Baseline 29 Radiating surface 30 Power Supply Department 31 Power supply lines 32 coaxial cable 33 Power supply line end 40 Connecting conductor 50 Passive components 51 First passive conductor 52 second passive conductor 53 Third passive conductor 54 Center of Gravity 55 Connectors 60 Dielectric substrate 70 Window Glass 80 vehicles 101 Antenna Device 111 antenna.

Claims

1. An antenna comprising a radiation plate, a ground plate and a passive element, The radiation plate has a radiation surface. The ground plate is arranged on the side of the radiation plate opposite to the radiation surface side via a dielectric. The passive element comprises a first passive conductor, a second passive conductor and a third passive conductor. In a top view of the radiation board, the first passive conductor is arranged in a first direction with the center of gravity of the radiation board as a reference, the second passive conductor is arranged in a second direction opposite to the first direction with the center of gravity of the radiation board as a reference, and the third passive conductor is connected to the first passive conductor and the second passive conductor. The third passive conductor includes a portion that passes through the vicinity of the center of gravity of the radiation board in a top view of the radiation board and extends along the first direction and the second direction.

2. The antenna according to claim 1, wherein: In a top view of the radiation board, when a direction orthogonal to the first direction is set as a third direction, a width of the third passive conductor in the third direction is set as W, and a length of the first passive conductor or the second passive conductor in the third direction is set as L, W / L satisfies W / L≦0.

50.

3. The antenna according to claim 2, wherein: The end of the third passive conductor is connected to the first passive conductor or the second passive conductor at a position in a range of 30% to 70% inclusive when the length L is 100%.

4. The antenna according to any one of claims 1 to 3, wherein: In a top view of the radiation plate, a direction perpendicular to the first direction is set as a third direction, a direction opposite to the third direction is set as a fourth direction, the third direction relative to a reference line passing through the center of gravity of the radiation plate and parallel to the first direction is set as positive, the fourth direction relative to the reference line is set as negative, and the length of the radiation surface in the third direction is set as D, The third passive conductor overlaps a range from the reference line to ±0.30×D in a plan view of the radiation plate.

5. The antenna according to any one of claims 1 to 3, wherein: In a top view of the radiation board, the second passive conductor has the same shape as the first passive conductor.

6. The antenna according to any one of claims 1 to 3, wherein: The outer edge of the radiation plate is a substantially quadrilateral having a pair of sides parallel to the first direction and a pair of sides parallel to a direction orthogonal to the first direction when viewed from above the radiation plate. An extended conductor, ie, a power supply line, connected to a power supply point of the radiation plate is arranged on a plane parallel to the radiation surface.

7. The antenna according to any one of claims 1 to 3, wherein: At least one of the first passive conductor and the second passive conductor does not overlap with the radiation plate in a plan view of the radiation plate.

8. The antenna according to any one of claims 1 to 3, wherein: At least one of the first passive conductor and the second passive conductor does not overlap with the ground plate in a plan view of the radiation plate.

9. The antenna according to any one of claims 1 to 3, wherein: The passive element has a point-symmetrical shape.

10. The antenna according to claim 9, wherein: In a top view of the radiation board, the center of gravity of the passive element overlaps with the center of gravity of the radiation board.

11. The antenna according to any one of claims 1 to 3, wherein: The first passive conductor and the second passive conductor are arranged on a side of the radiation plate opposite to the ground plate side.

12. The antenna according to any one of claims 1 to 3, wherein: The first passive conductor and the second passive conductor are arranged on a plane different from the radiation surface.

13. The antenna according to any one of claims 1 to 3, wherein: The third passive conductor has a bridge shape extending in a direction different from a direction parallel to the radiation surface and crossing the radiation surface.

14. The antenna according to claim 13, wherein: The first parasitic conductor and the second parasitic conductor are arranged on the same plane as the radiation surface so as not to overlap with the radiation plate in a plan view of the radiation plate.

15. The antenna according to any one of claims 1 to 3, wherein: A connector for connecting to a coaxial cable is provided and is arranged on the side opposite to the radiation surface with respect to the ground plate.

16. The antenna according to any one of claims 1 to 3, wherein: The third passive conductor is fixed by a dielectric.

17. The antenna according to claim 16, wherein: The first passive conductor and the second passive conductor are in contact with air except for portions connected to the third passive conductor.

18. A vehicle antenna device comprising a vehicle window glass and the antenna according to any one of claims 1 to 3, The radiation surface of the antenna is arranged to face the window glass, The radiation surface is inclined at an angle within ±15° relative to a vertical plane that is at right angles to the horizontal plane.

19. The vehicle antenna device according to claim 18, wherein: On the radiation surface, a straight line connecting the center of gravity of the radiation plate and the power supply point of the radiation plate is inclined at an angle within ±15° relative to a vertical plane perpendicular to the horizontal plane. The radio wave frequency band received by the antenna includes a 5.8 GHz frequency band or a 5.9 GHz frequency band.

20. The vehicle antenna device according to claim 18, wherein: The antenna is a V2X antenna.

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