EP4685997A1 - Antenna device and installation method for antenna device - Google Patents

Antenna device and installation method for antenna device

Info

Publication number
EP4685997A1
EP4685997A1 EP23928720.4A EP23928720A EP4685997A1 EP 4685997 A1 EP4685997 A1 EP 4685997A1 EP 23928720 A EP23928720 A EP 23928720A EP 4685997 A1 EP4685997 A1 EP 4685997A1
Authority
EP
European Patent Office
Prior art keywords
antenna
radio wave
transmissive body
wave transmissive
windshield
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP23928720.4A
Other languages
German (de)
French (fr)
Inventor
Bunpei Hara
Yusuke Yokota
Kazuki Yamada
Tomohiro Kato
Koki Kubo
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Honda Motor Co Ltd
Yokowo Co Ltd
Original Assignee
Honda Motor Co Ltd
Yokowo Co Ltd
Yokowo Mfg Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Honda Motor Co Ltd, Yokowo Co Ltd, Yokowo Mfg Co Ltd filed Critical Honda Motor Co Ltd
Publication of EP4685997A1 publication Critical patent/EP4685997A1/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/27—Adaptation for use in or on movable bodies
    • H01Q1/32—Adaptation for use in or on road or rail vehicles
    • H01Q1/325—Adaptation for use in or on road or rail vehicles characterised by the location of the antenna on the vehicle
    • H01Q1/3283—Adaptation for use in or on road or rail vehicles characterised by the location of the antenna on the vehicle side-mounted antennas, e.g. bumper-mounted, door-mounted
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q21/00—Antenna arrays or systems
    • H01Q21/28—Combinations of substantially independent non-interacting antenna units or systems

Definitions

  • the present invention relates to an antenna device and a method of mounting an antenna device.
  • the V2X antenna includes a square radiating element and parasitic elements that are disposed outside two opposing sides of the radiation element and have elongated rectangular shapes along the two opposing sides.
  • the V2X antenna is disposed on at least one of a windshield or a rear window of a vehicle such as an automobile.
  • Patent Document 1 International Publication No. WO2019/073667
  • Some communications should be able to provide stable communications in any of front, rear, left, and right directions of the vehicle.
  • the antenna system for some communications should be omnidirectional.
  • the antenna may be disposed on the windshield and the rear window.
  • the antennas may be added to both left and right sides of the vehicle.
  • adding antennas to both left and right sides of the vehicle may require extra antennas and processing units, which would increase costs.
  • An example of the object of the present invention is to ensure directivity over a wide range with a small number of antennas.
  • Other objects of the present invention will become apparent from the description of the present specification.
  • An aspect of the present invention is an antenna device including:
  • Another aspect of the present invention is a method of mounting an antenna device, including:
  • the directivity can be ensured over a wide range with a small number of antennas.
  • the X direction, the Y direction, and the Z direction are defined to describe directions.
  • the Z direction is a direction parallel to a vertical direction.
  • the X direction is one of horizontal directions perpendicular to the Z direction.
  • the Y direction is one of the horizontal directions perpendicular to the Z direction and the X direction.
  • the X direction is a front-rear direction
  • the Y direction is a left-right direction
  • the Z direction is an up-down direction.
  • directions indicated by arrows of each of the X-axis, the Y-axis, and the Z-axis are defined as a front direction, a left direction, and an upper direction, respectively.
  • the white circle with the black dot indicating the X-axis, the Y-axis, or the Z-axis indicates that the arrow indicated by the white circle points to the front side of the paper surface.
  • FIG. 1A is a top view of a vehicle 50 on which an antenna device 1 according to the embodiment is mounted.
  • FIG. 1B is a view of a windshield 510 and its surroundings of a vehicle 50 on which the antenna device 1 according to the embodiment is mounted as viewed from the left direction of the vehicle 50.
  • FIG. 1C is a view of a rear window 520 and its surroundings of the vehicle 50 on which the antenna device 1 according to the embodiment is mounted as viewed from the left direction of the vehicle 50.
  • FIG. 1A shows the mounting position of the antenna device 1 according to the embodiment on the vehicle 50.
  • descriptions with reference to FIGS. 1A to 1C are related not only to the antenna device 1 according to the embodiment but also to a method of mounting the antenna device 1 according to the embodiment.
  • the antenna device 1 includes a front antenna 10A and a rear antenna 10B.
  • the front antenna 10A can ensure the directivity in front and both left and right directions of the vehicle 50 and the rear antenna 10B can ensure the directivity in rear and both left and right directions of the vehicle 50.
  • the front antenna 10A and the rear antenna 10B are positioned on opposite sides to each other in the X direction.
  • the antenna device 1 can have an omnidirectional directivity by the front antenna 10A and the rear antenna 10B. That is, the directivity can be ensured over a wide range, as compared with the case where only one of the front antenna 10A and the rear antenna 10B is used.
  • the antenna device 1 may not include both the front antenna 10A and the rear antenna 10B and may include only one of the front antenna 10A or the rear antenna 10B.
  • the antenna device 1 may further include an additional antenna corresponding to the front antenna 10A or the rear antenna 10B, in addition to at least one of the front antenna 10A or the rear antenna 10B.
  • the additional antenna may be disposed in glass different from the windshield 510 and the rear window 520, such as a side glass or a rear quarter glass or a component of the vehicle 50, such as a spoiler, a bumper, a pillar, or a roof 502, for example.
  • the glass on which the additional antenna is disposed is a dielectric such as a radio wave transmissive body or a light transmissive body.
  • the additional antenna is disposed from the viewpoint of design of the vehicle 50, preventing obstruction of the field of view from the inside of the vehicle 50, and so on.
  • the front antenna 10A and the rear antenna 10B are vehicle-to-everything (V2X) antennas.
  • the front antenna 10A and the rear antenna 10B may be other antennas such as dedicated short range communications (DSRC), electronic toll collection (ETC), WiFi (registered trademark), Bluetooth (registered trademark), global navigation satellite system (GNSS), fifth generation mobile communication system (5G), and long term evolution (LTE).
  • DSRC dedicated short range communications
  • ETC electronic toll collection
  • WiFi registered trademark
  • GNSS global navigation satellite system
  • 5G fifth generation mobile communication system
  • LTE long term evolution
  • At least one of transmission or reception of radio waves of the front antenna 10A is performed by antenna elements covered by a front antenna case 110A, for example, which will be described later with reference to FIG. 2 .
  • the front antenna 10A and the rear antenna 10B are the same antenna.
  • the directivity characteristics, the angle at half maximum, the supported frequency, and the supported medium of the front antenna 10A are the same as the directivity characteristics, the angle at half maximum, the supported frequency, and the supported medium of the rear antenna 10B.
  • the directivity characteristics, the angle at half maximum, the supported frequency, and the supported medium of the front antenna 10A and the directivity characteristics, the angle at half maximum, the supported frequency, and the supported medium of the rear antenna 10B may be different from each other.
  • the front antenna 10A and the rear antenna 10B are schematically illustrated as antenna cases having a generally rectangular parallelepiped shape that accommodates antenna elements such as patch antennas.
  • the front antenna 10A and the rear antenna 10B are schematically illustrated as antenna cases having a generally rectangular parallelepiped shape.
  • the antenna cases having a generally rectangular parallelepiped shape of the front antenna 10A and the rear antenna 10B have the same configuration as a front antenna case 110A described later with reference to FIG. 2 , for example.
  • the vehicle 50 according to the embodiment is a sedan type automobile.
  • the vehicle 50 may be any type of automobile.
  • the vehicle 50 may be an automobile other than a sedan type, such as a van type or a sport utility vehicle (SUV) type.
  • SUV sport utility vehicle
  • the vehicle 50 according to the embodiment will be described as a sedan type automobile.
  • the vehicle 50 includes a body 500, a windshield 510, and a rear window 520.
  • the body 500 has a roof 502, a hood 504, and a trunk lid 506.
  • the roof 502 is not particularly limited, but is, for example, a steel plate roof, a glass roof, a resin roof, a carbon roof, or a combination thereof.
  • the hood 504 and the trunk lid 506 are, for example, conductive sheet metals made of materials such as aluminum and steel. However, a part of the hood 504 and the trunk lid 506 may be made of a resin part. A hatchback may be used instead of the trunk lid 506.
  • the roof 502 is positioned generally at the central portion of the body 500 in the X direction as viewed in the Z direction.
  • the hood 504 is positioned at the front portion of the body 500 in the X direction as viewed in the Z direction.
  • the windshield 510 is positioned between the front end of the roof 502 and the rear end of the hood 504 in the X direction as viewed in the Z direction.
  • the windshield 510 is a dielectric.
  • the windshield 510 is a radio wave transmissive body that transmits radio waves between the interior of the vehicle 50 and the space in front of the vehicle 50.
  • the windshield 510 is also a light transmissive body that transmits light such as visible light between the interior of the vehicle 50 and the space in front of the vehicle 50.
  • the trunk lid 506 is positioned at the rear portion of the body 500 in the X direction as viewed in the Z direction.
  • the rear window 520 is positioned between the rear end of the roof 502 and the front end of the trunk lid 506 in the X direction as viewed from the Z direction.
  • the rear window 520 is a dielectric.
  • the rear window 520 is a radio wave transmissive body that transmits radio waves between the inside of the vehicle 50 and the space behind the vehicle 50.
  • the rear window 520 is also a light transmissive body that transmits light such as visible light between the vehicle interior of the vehicle 50 and the space behind the vehicle 50.
  • the front antenna 10A is disposed such that the radiation surface, from which radio waves of the front antenna 10A are radiated, is directed forward the vehicle 50.
  • the radiation surface of the front antenna 10A is a front surface of the front antenna 10A.
  • the type of the antenna of the front antenna 10A is not particularly limited.
  • the front antenna 10A may be a patch antenna, a dipole type antenna or any other type of antenna.
  • the windshield 510 is disposed in front of the radiation surface of the front antenna 10A. That is, the front antenna 10A is disposed behind the windshield 510. Accordingly, the front antenna 10A is disposed on the inside of the vehicle with respect to the windshield 510.
  • the front antenna 10A radiates radio waves toward the windshield 510.
  • the hood 504 is positioned on the lower front side of the front antenna 10A.
  • the front antenna 10A is fixed to the rear surface of the windshield 510.
  • the rear surface of the windshield 510 is a surface of the windshield 510 on the inside of the vehicle.
  • the front antenna 10A may be disposed above or inside a dashboard positioned between the lower end of the windshield 510 and the rear end of the hood 504.
  • the front antenna 10A may be disposed while it is covered with a resin cover along with other electrical equipment.
  • a portion of the windshield 510 that overlaps with the projected image of the front antenna 10A in the X direction is referred to as a front overlapping portion 510a.
  • the image of the front antenna 10A is formed by projecting the antenna case of the front antenna 10A having a generally rectangular parallelepiped shape toward the windshield 510 in parallel with the X direction.
  • the two broken lines for indicating the front overlapping portion 510a extend from the upper surface and the lower surface of the front antenna 10A toward the front.
  • the front overlapping portion 510a is a portion of the windshield 510 positioned between the two broken lines. The same applies to the front overlapping portion 510a shown in FIG. 6A , FIG. 6B , FIG. 8 , FIG. 11 , and FIG. 13 which will be described later.
  • the front overlapping portion 510a is positioned generally at the central portion of the windshield 510 in the left-right direction as viewed from the Z direction.
  • the front overlapping portion 510a may be at a position deviated in the Y direction from generally the center of the windshield 510 in the left-right direction if other electrical equipment such as a wiper, a sensor, and a drive recorder, or black ceramic is present near the front antenna 10A.
  • the windshield 510 is inclined at a predetermined angle with respect to the X direction between the lower end portion and the upper end portion of the windshield 510 as viewed from the Y direction.
  • the windshield 510 is inclined obliquely upward from the rear end of the hood 504 toward the front end of the roof 502. Accordingly, the lower end portion of the windshield 510 is displaced forward with respect to the upper end portion of the windshield 510 in the X direction and the upper end portion of the windshield 510 is displaced backward with respect to the lower end portion of the windshield 510 in the X direction as viewed from the Y direction.
  • the front overlapping portion 510a is displaced to a side where the lower end portion of the windshield 510 is positioned with respect to the central portion between the upper end portion and the lower end portion of the windshield 510. Specifically, the front overlapping portion 510a is positioned at the lower end portion of the windshield 510. However, the front overlapping portion 510a may be at a position deviated from the lower end portion of the windshield 510 as appropriate if other electrical equipment such as a wiper, a sensor, and a drive recorder, or black ceramic is present near the front antenna 10A.
  • the rear antenna 10B is disposed such that the radiation surface, from which radio waves of the rear antenna 10B are radiated, is directed backward the vehicle 50.
  • the radiation surface of the rear antenna 10B is a rear surface of the rear antenna 10B.
  • the type of the antenna of the rear antenna 10B is not particularly limited.
  • the rear antenna 10B may be a patch antenna, a dipole type antenna or any other type of antenna.
  • the rear window 520 is disposed behind the radiation surface of the rear antenna 10B. That is, the rear antenna 10B is disposed in front of the rear window 520. Accordingly, the rear antenna 10B is disposed on the inside of the vehicle with respect to the rear window 520.
  • the rear antenna 10B radiates radio waves toward the rear window 520.
  • the trunk lid 506 is positioned on the lower rear side of the rear antenna 10B.
  • the rear antenna 10B is fixed to the front surface of the rear window 520.
  • the front surface of the rear window 520 is a surface of the rear window 520 on the inside of the vehicle.
  • the rear antenna 10B may be disposed above or inside a rear parcel shelf positioned between the lower end of the rear window 520 and the front end of the trunk lid 506.
  • the rear antenna 10B may be positioned while it is covered with a resin cover along with other electrical equipment.
  • a portion of the rear window 520 that overlaps with the projected image of the rear antenna 10B in the X direction is referred to as a rear overlapping portion 520a.
  • the image of the rear antenna 10B is formed by projecting the antenna case of the rear antenna 10B having a generally rectangular parallelepiped shape toward the rear window 520 in parallel with the X direction.
  • the two broken lines for indicating the rear overlapping portion 520a extend backward from the upper surface and the lower surface of the rear antenna 10B.
  • the rear overlapping portion 520a is a portion of the rear window 520 positioned between the two broken lines. The same applies to a rear overlapping portion 520a shown in FIG. 10A and FIG. 10B which will be described later.
  • the rear overlapping portion 520a is positioned generally at the central portion of the rear window 520 in the left-right direction as viewed from the Z direction.
  • the rear overlapping portion 520a may be at a position deviated in the Y direction from generally the center of the rear window 520 in the left-right direction if other electrical components such as a wiper, a sensor, and a drive recorder, or black ceramic is present near the rear antenna 10B.
  • the rear window 520 is inclined at a predetermined angle with respect to the X direction between the lower end portion and the upper end portion of the rear window 520 as viewed from the Y direction.
  • the rear window 520 is inclined obliquely upward from the front end of the trunk lid 506 toward the rear end of the roof 502. Accordingly, the lower end portion of the rear window 520 is displaced backward with respect to the upper end portion of the rear window 520 in the X direction and the upper end portion of the rear window 520 is displaced forward with respect to the lower end portion of the rear window 520 in the X direction as viewed in the Y direction.
  • the rear overlapping portion 520a is displaced to a side where the lower end portion of the rear window 520 is positioned with respect to the central portion between the upper end portion and the lower end portion of the rear window 520. Specifically, the rear overlapping portion 520a is positioned at the lower end portion of the rear window 520. However, the rear overlapping portion 520a may be at a position deviated from the lower end portion of the rear window 520 as appropriate if other electrical equipment such as a wiper, a sensor, and a drive recorder, or black ceramic is present near the rear antenna 10B.
  • FIG. 2 is a perspective view showing a configuration example of the front antenna 10A according to the embodiment.
  • the descriptions regarding the front antenna 10A using FIG. 2 can also be applied to the rear antenna 10B.
  • the configurations of the front antenna 10A and the rear antenna 10B are not limited to the configuration example shown in FIG. 2 .
  • the front antenna 10A includes a front antenna case 110A and a front cable 120A.
  • the front antenna case 110A has a generally rectangular parallelepiped shape.
  • the front antenna case 110A covers the antenna element, not illustrated in FIG. 2 .
  • This antenna element is a patch antenna, for example.
  • the antenna covered by the front antenna case 110A is not limited to the patch antenna.
  • the front antenna case 110A is radio wave transmissive.
  • the front antenna case 110A is made of a resin, for example.
  • the front antenna case 110A is provided with an attachment structure.
  • the front antenna case 110A is fixed to a fixing structure such as a bracket provided to the vehicle 50 via the mounting structure.
  • the front cable 120A is drawn from the front antenna case 110A.
  • the front cable 120A is electrically connected to the antenna element covered by the front antenna case 110A.
  • a signal obtained from the antenna element covered by the front antenna case 110A is output through the front cable 120A.
  • the method of outputting the signal obtained from the antenna element is not limited to the method using the front cable 120A.
  • a substrate such as a printed circuit board (PCB) on which the antenna element is mounted and a connector such as a coaxial connector may be electrically connected to each other. When the substrate and the connector are electrically connected to each other, a signal obtained from the antenna element is output via the substrate and the connector.
  • PCB printed circuit board
  • FIG. 3A is a directivity gain diagram in a horizontal plane when the antenna device 1 according to a first example is mounted on the vehicle 50.
  • FIG. 3B is a directivity gain diagram in a horizontal plane when the antenna device 1K according to a comparative example is mounted on the vehicle 50.
  • FIG. 4 is a top view of a vehicle 50 on which an antenna device 1K according to the comparative example is mounted.
  • the horizontal plane is a plane perpendicular to the Z direction.
  • the antenna device 1 according to the first example is an example of the antenna device 1 according to the embodiment.
  • the front overlapping portion 510a is positioned at the lower end portion of the windshield 510.
  • the rear overlapping portion 520a is positioned at the lower end portion of the rear window 520.
  • the front antenna 10A and the rear antenna 10B are the same antenna. That is, the angle at half maximum of the single characteristic of the front antenna 10A and the angle at half maximum of the single characteristic of the rear antenna 10B are the same.
  • the antenna device 1K according to the comparative example will be described with reference to FIG. 4 .
  • the antenna device 1K according to the comparative example is the same as the antenna device 1 according to the first example except for the following points.
  • the front antenna 10A according to the first example and the front antenna 10A according to the comparative example are the same antenna.
  • the front overlapping portion 510aK according to the comparative example is positioned at the central portion of the windshield 510 in the left-right direction in the same way as the front overlapping portion 510a according to the first example as viewed in the Z direction.
  • the front overlapping portion 510aK according to the comparative example differs from the front overlapping portion 510a according to the first example in that it is positioned at the central portion between the upper end portion and the lower end portion of the windshield 510 as viewed in the Y direction.
  • the rear antenna 10B according to the first example and the rear antenna 10B according to the comparative example are the same antenna.
  • the rear overlapping portion 520aK according to the comparative example is positioned at the central portion of the rear window 520 in the left-right direction in the same way as the rear overlapping portion 520a according to the first example as viewed in the Z direction.
  • the rear overlapping portion 520aK according to the comparative example differs from the rear overlapping portion 520a according to the first example in that it is positioned in the central portion between the upper end portion and the lower end portion of the rear window 520 as viewed in the Y direction.
  • the directivity gain in the horizontal plane of the antenna device 1 according to the first example and the antenna device 1K according to the comparative example will be described with reference to FIGS. 3A and 3B .
  • the numbers attached to the outer periphery of the gain diagrams of FIGS. 3A and 3B indicate directions (unit: °).
  • the numbers from the center to 270° direction of the gain diagrams of FIGS. 3A and 3B indicate gains (unit: dBi).
  • 0° direction is the front side of the vehicle 50
  • 180° direction is the rear side of the vehicle 50
  • 90° direction is the left side of the vehicle 50
  • 270° direction is the right side of the vehicle 50.
  • the solid line pattern in FIG. 3A shows the directivity gain in the horizontal plane of the front antenna 10A according to the first example.
  • the broken line pattern of FIG. 3A shows the directivity gain in the horizontal plane of the rear antenna 10B according to the first example.
  • the solid line pattern in FIG. 3B shows the directivity gain in the horizontal plane of the front antenna 10A according to the comparative example.
  • the broken line pattern in FIG. 3B shows the directivity gain in the horizontal plane of the rear antenna 10B according to the comparative example.
  • the gain of the front antenna 10A according to the first example in the 90° direction is -1.58 dBi.
  • the gain of the front antenna 10A according to the comparative example in the 90° direction is -12.15 dBi. Accordingly, it can be seen that the gain of the front antenna 10A according to the first example in the 90° direction is significantly increased as compared with the gain of the front antenna 10A according to the comparative example in the 90° direction.
  • the width at half maximum of the front antenna 10A can be widened and the gain of the front antenna 10A in the left-right direction of the vehicle 50 can be improved by changing the mounting position of the front antenna 10A.
  • the gain of the rear antenna 10B according to the first example in the 90° direction is -1.53 dBi.
  • the gain of the rear antenna 10B according to the comparative example in the 90° direction is -11.24 dBi. Accordingly, it can be seen that the gain of the rear antenna 10B according to the first example in the 90° direction is significantly increased as compared with the gain of the rear antenna 10B according to the comparative example in the 90° direction.
  • the width at half maximum of the rear antenna 10B can be widened and the gain of the rear antenna 10B in the left-right direction of the vehicle 50 can be improved by changing the mounting position of the rear antenna 10B.
  • the difference between the maximum value and the minimum value of the gain of the front antenna 10A at 0° or more and 90° or less and 270° or more and less than 360° and the gain of the rear antenna 10B at 90° or more and 270° or less is 8.21 dB.
  • the difference between the maximum value and the minimum value of the gain of the front antenna 10A at 0° or more and 90° or less and 270° or more and less than 360° and the gain of the rear antenna 10B at 90° or more and 270° or less is 16.02 dB. Therefore, the ripple is reduced in the first example as compared with the comparative example. Accordingly, it can be seen that the antenna device 1 according to the first example ensures the directivity over a wider range than the antenna device 1K according to the comparative example. In particular, the antenna device 1 according to the first example can have an omnidirectional directivity.
  • the angle at half maximum of the single characteristic of the front antenna 10A and the angle at half maximum of the single characteristic of the rear antenna 10B are the same. However, the angle at half maximum of the single characteristic of the front antenna 10A and the angle at half maximum of the single characteristic of the rear antenna 10B may be different from each other.
  • the angles at half maximum of the front antenna 10A and the rear antenna 10B can be determined such that the directivity gain in the horizontal plane of the front antenna 10A and the rear antenna 10B combined has omnidirectional directivity.
  • the radiation characteristics of the front antenna 10A when the windshield 510 is present in front of the radiation surface of the front antenna 10A will be described.
  • the front antenna 10A overlaps with the central portion between the upper end portion and the lower end portion of the windshield 510 in the front-rear direction of the vehicle 50.
  • the front antenna 10A overlaps with the lower end portion of the windshield 510 in the front-rear direction of the vehicle 50.
  • the irradiation area of the radio waves radiated forward and downward from the front antenna 10A to the rear surface of the windshield 510 in the embodiment and the first example can be smaller than the irradiation area of the radio waves radiated forward and downward from the front antenna 10A to the rear surface of the windshield 510 in the comparative example. Therefore, the scattering of the radio waves radiated forward and downward from the front antenna 10A to the rear surface of the windshield 510 can be reduced in the embodiment and the first example as compared with the comparative example. Accordingly, the gain of the embodiment and the first example can be higher than the gain of the comparative example by reducing the scattering of the radio waves on the rear surface of the windshield 510.
  • FIG. 5A is a directivity gain diagram in a horizontal plane when the front antenna 10A overlaps the upper end portion, the central portion, or the lower end portion of the windshield 510 in the front-rear direction of the vehicle 50.
  • the central portion of the windshield 510 is a central portion between the upper end portion and the lower end portion of the windshield 510 as viewed in the Y direction with reference to FIG. 1B .
  • 0° direction is the front side of the vehicle 50
  • 180° direction is the rear side of the vehicle 50
  • 90° direction is the left side of the vehicle 50
  • 270° direction is the right side of the vehicle 50.
  • FIG. 5A 0° direction is the front side of the vehicle 50
  • 180° direction is the rear side of the vehicle 50
  • 90° direction is the left side of the vehicle 50
  • 270° direction is the right side of the vehicle 50.
  • the windshield 510 is disposed on the 0° direction side of the front antenna 10A.
  • the dotted line pattern, the broken line pattern, and the solid line pattern in FIG. 5A show the directivity gains in the horizontal plane when the front antenna 10A overlaps the upper end portion, the central portion, and the lower end portion of the windshield 510 in the X direction respectively.
  • the gains in the 90° direction when the front antenna 10A overlaps the upper end portion, the central portion, and the lower end portion of the windshield 510 in the X direction are -11.99 dBi, -12.15 dBi, and -1.58 dBi, respectively.
  • FIG. 5B is a directivity gain diagram in a vertical plane when the front antenna 10A overlaps the upper end portion, the central portion, or the lower end portion of the windshield 510 in the front-rear direction of the vehicle 50.
  • the central portion of the windshield 510 is a central portion between the upper end portion and the lower end portion of the windshield 510 as viewed in the Y direction with reference to FIG. 1B .
  • 90° direction is the front side of the vehicle 50
  • -90° direction is the rear side of the vehicle 50
  • 0° direction is the upper side of the vehicle 50
  • 180° direction is the lower side of the vehicle 50.
  • the windshield 510 is disposed on the 90° direction side of the front antenna 10A.
  • the dotted line pattern, the broken line pattern, and the solid line pattern in FIG. 5B show the directivity gains in the horizontal plane when the front antenna 10A overlaps the upper end portion, the central portion, and the lower end portion of the windshield 510 in the X direction respectively.
  • the gain deviation (the difference between the maximum value and the minimum value of the gain) in the range of 60° to 120° decreases as the front overlapping portion 510a goes from the upper end to the lower end of the windshield 510.
  • the front antenna 10A overlaps the lower end portion of the windshield 510 in the X direction. Therefore, the directivity can be stably ensured over a wide range in the first example compared to the case where the front antenna 10A overlaps the upper end portion or the central portion of the windshield 510 in the X direction.
  • the ensuring of the directivity over a wide range in the first example can be realized without adding antennas on both left and right sides of the vehicle 50. Therefore, the directivity can be ensured over a wide range with a small number of antennas in the first example.
  • the stable ensuring of the directivity over a wide range in the first example can be better as the angle at half maximum of the front antenna 10A increases.
  • the front overlapping portion 510a may be positioned at a portion positioned forward from the central portion of the windshield 510 in the Z direction by a predetermined distance, instead of the lower end portion of the windshield 510.
  • the directivity can be ensured over a wide range with a small number of antennas as compared with the case where the front overlapping portion 510a is positioned at the central portion of the windshield 510 in the Z direction or the upper end portion of the windshield 510 as viewed from the Y direction.
  • Embodiment 1 and the first example use the characteristics of the propagation of the radio waves radiated from the front antenna 10A or the rear antenna 10B through the conductor-made sheet metal, such as the hood 504 and the trunk lid 506.
  • Embodiment 1 and the first example ensures the gain of the antenna device 1 in the left-right direction of the vehicle 50 by using the characteristic that the radio waves radiated from each antenna propagate through the conductor.
  • a hatchback may be used instead of the trunk lid 506 as the conductor used for the propagation of the radio waves. The hatchback can also be used for radio wave propagation in the same way as the trunk lid 506.
  • FIG. 6A is a diagram showing a configuration of a part of the vehicle 50 with a front conductor 500a on the lower front side of the front antenna 10A.
  • FIG. 6B is a diagram showing a configuration of a part of the vehicle 50 without the front conductor 500a on the lower front side of the front antenna 10A.
  • FIGS. 6A and 6B show a comparative configuration of the presence or absence of a front conductor 500a on the lower front side of the front antenna 10A.
  • the hood 504 is the front conductor 500a.
  • the front conductor 500a is disposed in front of the lower end portion of the windshield 510 as viewed from the Y direction. Specifically, the front conductor 500a extends frontward and downward from the lower end portion of the windshield 510 as viewed from the Y direction.
  • the directivity gain in the horizontal plane is almost the same regardless of the presence or absence of the front conductor 500a.
  • the gain deviation (the difference between the maximum value and the minimum value of the gain) in the range of 60° to 120° in front of the radiation direction of the front antenna 10A is reduced when the front conductor 500a is provided as compared with when the front conductor 500a is not provided.
  • the front end of the front conductor 500a is inclined downward by 30°, 60°, or 90° around the portion of the front conductor 500a near the lower end of the windshield 510 with respect to the 0° inclination of the front conductor 500a from the X direction as shown in FIG. 8 .
  • the front conductor 500a is parallel with the X direction.
  • the solid line pattern, the broken line pattern, the dotted line pattern, and the dash-dotted line pattern in FIG. 9A and FIG. 9B show gains when the inclinations of the front conductor 500a with respect to the X direction are 0°, 30°, 60°, and 90°, respectively.
  • the directivity gain in the horizontal plane of the horizontal plane at 0° or more and 90° or less and 270° or more and less than 360° is the lowest when the inclination of the front conductor 500a with respect to the X direction is 90°, and is improved as the front conductor 500a is gradually closer to the X direction. It is understood that the front conductor 500a hardly contributes to the radiation of the radio waves from the front antenna 10A when the front conductor 500a is perpendicular to the X direction.
  • the radio waves radiated from the front antenna 10A can propagate through the front conductor 500a and the gain on the front side of the front antenna 10A can be improved.
  • the angle of the front conductor 500a with respect to the X direction is -6° (angle downward closer to the X direction)
  • the radio wave propagates to the elevation angle of -6° and the gain in the depression angle direction from the horizontal plane is improved. Therefore, the inclination of the front conductor 500a with respect to the X direction is desirably set -30° or more and +30° or less, for example, when communicating with others by the V2X communication using the front antenna 10A.
  • the gain of the front antenna 10A can be improved by setting the inclination of the front conductor 500a with respect to the X direction to this range.
  • the shape of the front conductor 500a is not particularly limited.
  • the shape of the front conductor 500a may be a flat plate.
  • a part of the front conductor 500a may be provided with an uneven shape or an R shape.
  • the propagation characteristics of the radio waves from the horizontal plane to the lower side can be improved and the directivity gain of the depression angle can be increased by shaping the front conductor 500a inclined downward toward the front end of the body 500.
  • FIG. 8 The descriptions regarding the front antenna 10A using FIG. 8 , FIG. 9A , and FIG. 9B can be also applied to the rear antenna 10B.
  • FIG. 10A is a view showing a first example of the rear conductor 500b according to the embodiment.
  • FIG. 10B is a view showing a second example of the rear conductor 500b according to the embodiment.
  • the rear conductor 500b shown in FIG. 10A or FIG. 10B has a hatchback or a structure similar to a hatchback.
  • the hatchback of the van is close to perpendicular to the X direction.
  • a part of the rear conductor 500b may extend generally parallel to the X direction from the lower end portion of the rear window 520.
  • the directivity gain in the horizontal plane of the rear antenna 10B can be improved as compared with the case where the rear conductor 500b is simply perpendicular to the X direction.
  • FIG. 10A or FIG. 10B has a hatchback or a structure similar to a hatchback.
  • the hatchback of the van is close to perpendicular to the X direction.
  • a part of the rear conductor 500b may extend generally parallel to the X direction from the lower end portion of the rear window 520.
  • the directivity gain in the horizontal plane of the rear antenna 10B can be improved as compared with the case where the rear conductor 500b is simply perpendicular to the X
  • the rear conductor 500b includes a portion generally parallel to the X direction and a portion extending from the front end of the portion generally parallel to the X direction and generally parallel to the Z direction.
  • the rear conductor 500b includes a portion generally parallel to the X direction and a portion extending from the rear end of the portion generally parallel to the X direction and generally parallel to the Z direction.
  • the rear conductor 500b can be formed by various methods. For example, a part of the body 500 may be bent in an L-shape. Alternatively, the conductor generally parallel to the X direction may be added later when the conductor generally parallel to the Z direction is provided in advance. Alternatively, a spoiler may be used. The rear conductor 500b may be used as a conductor alone. Alternatively, the rear conductor 500b may be integrated with the body 500. The rear conductor 500b may be attached to the body 500 while it is provided at least one of outside or inside the resin material.
  • the influence of the black ceramic 512 provided on the windshield 510 and the spacing between the black ceramic 512 and the front antenna 10A will be described.
  • the following descriptions regarding the influence of the black ceramic 512 provided on the windshield 510 and the spacing between the black ceramic 512 and the front antenna 10A are also applicable to the influence of the black ceramic provided on the rear window 520 and the spacing between the black ceramic and the rear antenna 10B.
  • Black ceramic is printed on the surface of the peripheral edge of glass such as a windshield 510 and a rear window 520.
  • the black ceramic has a role of protecting an adhesive used when glass such as a windshield 510 and a rear window 520 is assembled to the body 500.
  • the black ceramic generally contains alumina and titanium carbide added to alumina, as well as other substances if required.
  • the alumina is a substance with a low dissipation factor.
  • the titanium carbide on the other hand, is a conductive material. For this reason, there is a possibility that some electromagnetic waves transmitted through the black ceramic flow as a current to the titanium carbide and are converted into heat. This phenomenon is the same as the behavior of dielectric loss radio wave absorbers and is a factor that inhibits radio wave transmission.
  • the antennas is desirably spaced apart from the black ceramic by a predetermined spacing when the antennas such as the front antenna 10A and the rear antenna 10B are disposed at the ends of the glass such as the windshield 510 and the rear window 520.
  • the front overlapping portion 510a and the black ceramic are desirably displaced from each other.
  • the rear overlapping portion 520a and the black ceramic are desirably displaced from each other.
  • FIG. 11 is a view of the black ceramic 512 of the windshield 510 and the front antenna 10A as viewed from the left direction of the vehicle 50.
  • the front antenna 10A is illustrated as the antenna case having a generally rectangular parallelepiped shape that accommodates the antenna element.
  • the black ceramic 512 is provided on the rear surface of the lower end of the windshield 510.
  • the black ceramic 512 is almost impermeable to light.
  • the portion of the lower end of the windshield 510 provided with the black ceramic 512 does not function as a light transmissive body.
  • the lower end of the portion functioning as the light transmissive body of the windshield 510 is the upper end of the black ceramic 512.
  • the front overlapping portion 510a and the black ceramic 512 are displaced from each other.
  • the distance L from the level of the upper end of the black ceramic 512 to the lower surface of the front antenna 10A is 20 mm, for example.
  • the distance L shown in FIG. 11 can be freely set as long as the black ceramic 512 does not interfere with the radio waves radiated from the rear antenna 10B.
  • the black ceramic 512 is present in the radiation direction of the radio waves of the front antenna 10A, there is a possibility that the gain of the front antenna 10A is reduced. For this reason, the front antenna 10A is spaced apart by a predetermined spacing from the black ceramic 512 in the Z direction.
  • the rear antenna 10B can also be spaced apart by a predetermined spacing from the black ceramic provided at the lower end of the rear window 520 in the same way as the front antenna 10A.
  • the distance from the level of the upper end of the black ceramic provided at the lower end of the rear window 520 to the lower surface of the housing of the rear antenna 10B is 5 mm, for example. This distance can be freely set as long as the black ceramic does not interfere with the radio waves radiated from the rear antenna 10B.
  • FIG. 12 is a view of the front antenna 10A, the windshield 510, and the black ceramic 512 as viewed from the front of the vehicle 50.
  • the front antenna 10A is illustrated as the antenna case having a generally rectangular parallelepiped shape that accommodates the antenna element.
  • the black ceramic 512 defines a recess portion 512a as viewed from the front.
  • the recess portion 512a at least partially surrounds the front overlapping portion 510a as viewed from the front.
  • the recess portion 512a at least partially surrounds the lower end of the front antenna 10A as viewed from the front. Accordingly, the overlapping between the front antenna 10A and the black ceramic 512 in the X direction can be avoided by the recess portion 512a. Therefore, the degree of freedom of the mounting position of the front antenna 10A can be increased as compared with the case where the recess portion 512a is not provided. Accordingly, the front antenna 10A can be disposed closer to the lower end of the windshield 510 as viewed from the front and the gain of the front antenna 10A can be improved as compared with the case where the recess portion 512a is not provided.
  • the descriptions regarding the front antenna 10A, the windshield 510, and the black ceramic 512 using FIG. 12 can be also applied to the rear antenna 10B, the rear window 520, and the black ceramic provided in the rear window 520. That is, the black ceramic provided on the rear window 520 may also define a recess portion corresponding to the recess portion 512a of the black ceramic 512 provided on the windshield 510.
  • the angle of the windshield 510 with respect to the X direction contributes to at least one of transmission or scattering of radio waves emitted from the front antenna 10A.
  • the reflection of radio waves by the windshield 510 can be minimized when the angle of the rear surface of the front overlapping portion 510a with respect to the X direction is set to 10° or more and 40° or less.
  • the angle of the windshield 510 with respect to the X direction is about 31°.
  • the angle of the rear window 520 with respect to the X direction is about 23.5°.
  • the angles of the windshield 510 and the rear window 520 with respect to the X direction may be freely set if a desired antenna gain can be obtained in any range of the elevation angle and the azimuth angle.
  • the spacing between the front antenna 10A and the windshield 510 also contributes to the radiation of radio waves from the front antenna 10A. For this reason, the front antenna 10A and the windshield 510 are desirably spaced apart by a predetermined spacing. The same applies to the rear antenna 10B and the rear window 520.
  • FIG. 13 is a view of the front antenna 10A and the windshield 510 as viewed from the left direction of the vehicle 50.
  • the front antenna 10A is illustrated as the antenna case having a generally rectangular parallelepiped shape that accommodates the antenna element.
  • the spacing Gx in the X direction between the front surface of the front antenna 10A and the portion of the rear surface of the windshield 510 closest to the front surface of the front antenna 10A in the X direction is 20 mm
  • the spacing Gz in the Z direction between the upper surface of the front antenna 10A and the portion of the rear surface of the windshield 510 closest to the upper surface of the front antenna 10A in the Z direction is 11.8 mm.
  • the spacing in the X direction between the rear surface of the rear antenna 10B and the portion of the front surface of the rear window 520 closest to the rear surface of the rear antenna 10B in the X direction is 20 mm
  • the spacing in the Z direction between the upper surface of the rear antenna 10B and the portion of the front surface of the rear window 520 closest to the upper surface of the rear antenna 10B in the Z direction is 8.5 mm.
  • the spacing Gx shown in FIG. 13 is desirably 1/4 times or more the wavelength of the operation frequency of the front antenna 10A, for example.
  • the spacing Gx shown in FIG. 13 is desirably 1/2 or less of the wavelength of the operation frequency of the front antenna 10A, for example.
  • the spacing Gz shown in FIG. 13 is desirably 1/10 times or more of the wavelength of the operation frequency of the front antenna 10A, for example. The same applies to the spacing between the rear antenna 10B and the rear window 520.
  • the spacing between the front antenna 10A and the windshield 510 and the spacing between the rear antenna 10B and the rear window 520 are not limited to the examples described above.
  • the spacings may be freely set if a desired antenna gain can be achieved in any range of the elevation angle and the azimuthal angle.
  • the antennas such as the front antenna 10A and the rear antenna 10B may overlap with a radio wave transmissive body different from the glass such as the windshield 510 and the rear window 520.
  • the radio wave transmissive body include resin bodies such as a resin panel, a resin cover, a resin component, and the like.
  • the resin body is radio wave transmissive.
  • the resin body may or may not be light transmissive.
  • the resin body is disposed inside the vehicle, for example.
  • the resin body is provided for the purpose of fixing an antenna or surrounding components of the antenna, improving appearance and design, improving dustproof, waterproof, or durability, and the like.
  • the resin body such as a resin panel may be present on the radiation direction side of the antenna.
  • the resin body may be disposed between the antenna and the glass, for example.
  • a resin body such as a resin cover may cover at least a portion of the antenna.
  • the resin body may cover the antenna with the resin body open on the side on which the glass is positioned with respect to the antenna, for example.
  • the antenna may be disposed in the space enclosed by the resin body and the glass.
  • the resin body may cover the antenna including a side on which the glass is positioned with respect to the antenna.
  • the antenna may be disposed in the space enclosed by the resin body.
  • a resin body such as a resin component may be provided as a bracket that fixes the antenna to the vehicle.
  • the antenna radiates radio waves from the rear side toward the resin body.
  • a portion of the resin body overlapping with the projected image of the antenna in the front-rear direction is referred to as an overlapping portion of the resin body.
  • the overlapping portion of the resin body is displaced to a side on which the lower end portion of the resin body is positioned with respect to the central portion between the upper end portion and the lower end portion of the resin body in the same way as the front overlapping portion 510a of the embodiment.
  • the scattering of radio waves radiated from the antenna on the resin body can be reduced and the directivity gain can be improved as compared with the case where the overlapping portion of the resin body is positioned on the central portion of the resin body or is displaced to the side on which the upper end portion of the resin body is positioned with respect to the central portion of the resin body.
  • a conductor such as a sheet metal may be provided on the lower front side of the antenna as in the embodiment. As in the embodiment, the conductor is disposed in front of the lower end portion of the resin body.
  • the directivity gain can be improved when the conductor is provided as compared with when the conductor is not provided.
  • an antenna device includes an antenna to radiate radio waves toward a radio wave transmissive body, the radio wave transmissive body including both end portions opposite to each other, the radio wave transmissive body being inclined at a predetermined angle with respect to a predetermined direction between the both end portions from one side to the other side in the predetermined direction, the radio waves being radiated from the other side, in which a portion of the radio wave transmissive body that overlaps a projected image of the antenna in the predetermined direction is displaced to a side on which an end portion of the both end portions on the one side of the radio wave transmissive body is positioned with respect to a central portion between the both end portions of the radio wave transmissive body.
  • the "predetermined direction” corresponds to the "X direction” of the embodiment and variant described above.
  • the "radio wave transmissive body” corresponds to the “windshield” and the “rear window” of the embodiment and variant described above.
  • the “antenna” corresponds to the "front antenna” and the “rear antenna” of the embodiment and variant described above.
  • the scattering of radio waves radiated from the antenna on the radio wave transmissive body can be reduced as compared to the case where the portion of the radio wave transmissive body overlapping the image of the antenna is positioned at the central portion of the radio wave transmissive body or is displaced to a side where the other end portion of the radio wave transmissive body is positioned with respect to the central portion of the radio wave transmissive body.
  • the directivity can be ensured over a wide range with a small number of antennas as compared with the case where the portion of the radio wave transmissive body that overlaps the image of the antenna is positioned at the central portion of the radio wave transmissive body or is displaced to a side where the other end portion of the radio wave transmissive body is positioned with respect to the central portion of the radio wave transmissive body.
  • a plurality of the antennas is positioned on opposite sides in the predetermined direction.
  • the directivity can be ensured over a wide range as compared with the case where a single antenna is used.
  • the antenna is positioned with a conductor disposed on the one side with respect to the end portion on the one side of the radio wave transmissive body.
  • the radio waves radiated from the antenna can propagate through the conductor. Therefore, the gain of the antenna can be ensured as compared with the case where the conductor is not disposed.
  • the antenna is positioned with the portion of the radio wave transmissive body that overlaps the image of the antenna and a black ceramic provided at the radio wave transmissive body displaced from each other.
  • the black ceramic can be less likely to inhibit the transmission of the radio wave radiated from the antenna than when the portion of the radio wave transmissive body that overlaps the image of the antenna and the black ceramic overlap each other. Therefore, the gain of the antenna can be improved as compared with the case where the portion of the radio wave transmissive body that overlaps the image of the antenna and the black ceramic overlap each other.
  • the black ceramic defines a recess portion at least partially surrounding the portion of the radio wave transmissive body that overlaps the image of the antenna.
  • the antenna and the portion of the radio wave transmissive body that overlaps the image of the antenna are spaced apart in the predetermined direction by a spacing of 1/4 times or more and 1/2 times or less of a wavelength of an operation frequency of the antenna.
  • the change in the characteristics of the antenna can be reduced as compared with the case where the spacing in the predetermined direction between the antenna and the portion of the radio wave transmissive body that overlaps the image of the antenna is less than 1/4 of the wavelength of the operation frequency of the antenna.
  • the reflection of radio waves radiated from the antenna on the radio wave transmissive body can be reduced as compared with the case where the spacing in the predetermined direction between the antenna and the portion of the radio wave transmissive body that overlaps the image of the antenna is more than 1/2 of the wavelength of the operation frequency of the antenna.
  • the radio wave transmissive body is a light transmissive body.
  • the directivity can be ensured over a wide range with a small number of antennas when the antenna is disposed on the light transmissive body.
  • the antenna is a V2X antenna.
  • the directivity can be ensured over a wide range with a small number of V2X antennas.
  • a method of mounting an antenna device includes positioning an antenna to radiate radio waves toward a radio wave transmissive body, the radio wave transmissive body including both end portions opposite to each other, the radio wave transmissive body being inclined at a predetermined angle with respect to a predetermined direction between the both end portions from one side to the other side in the predetermined direction, the radio waves being radiated from the other side, in which a portion of the radio wave transmissive body that overlaps a projected image of the antenna in the predetermined direction is displaced to a side on which an end portion of the both end portions on the one side of the radio wave transmissive body is positioned with respect to a central portion between the both end portions of the radio wave transmissive body.
  • the directivity can be ensured over a wide range with a small number of antennas as in Aspect 1.
  • a plurality of the antennas is positioned on opposite sides in the predetermined direction.
  • the directivity can be ensured over a wide range as compared with the case where a single antenna is used.
  • the antenna is positioned with a conductor disposed on the one side with respect to the end portion on the one side of the radio wave transmissive body.
  • the gain of the antenna can be ensured, as in Aspect 3, as compared with the case where the conductor is not disposed.
  • the antenna is positioned with the portion of the radio wave transmissive body that overlaps the image of the antenna and a black ceramic provided at the radio wave transmissive body displaced from each other.
  • the gain of the antenna can be improved, as in Aspect 4, as compared with the case where the portion of the radio wave transmissive body that overlaps the image of the antenna and the black ceramic overlap each other.
  • the black ceramic defines a recess portion at least partially surrounding the portion of the radio wave transmissive body that overlaps the image of the antenna.
  • the degree of freedom of the mounting position of the antenna can be increased, as in Aspect 5, as compared with the case where the recess portion is not provided.
  • the antenna and the portion of the radio wave transmissive body that overlaps the image of the antenna are spaced apart in the predetermined direction by a spacing of 1/4 times or more and 1/2 times or less of a wavelength of an operation frequency of the antenna.
  • the change in the characteristics of the antenna and the reflection of the radio wave radiated from the antenna on the radio wave transmissive body can be reduced as in Aspect 6.
  • the radio wave transmissive body is a light transmissive body.
  • the directivity can be ensured over a wide range with a small number of antennas when the antenna is disposed on the light transmissive body.
  • the antenna is a V2X antenna.
  • the directivity can be ensured over a wide range with a small number of V2X antennas.
  • 1,1K antenna device 10A front antenna, 10B rear antenna, 50 vehicle, 110A front antenna case, 120A front cable, 500 body, 500a front conductor, 500b rear conductor, 502 roof, 504 hood, 506 trunk lid, 510 windshield, 510a, 510aK front overlapping portion, 512 black ceramic, 512a recess portion, 520 rear window, 520a, 520aK rear overlapping portion

Landscapes

  • Engineering & Computer Science (AREA)
  • Remote Sensing (AREA)
  • Details Of Aerials (AREA)

Abstract

An antenna device includes an antenna to radiate radio waves toward a radio wave transmissive body, the radio wave transmissive body including both end portions opposite to each other, the radio wave transmissive body being inclined at a predetermined angle with respect to a predetermined direction between the both end portions from one side to the other side in the predetermined direction, the radio waves being radiated from the other side, in which a portion of the radio wave transmissive body that overlaps a projected image of the antenna in the predetermined direction is displaced to a side on which an end portion of the both end portions on the one side of the radio wave transmissive body is positioned with respect to a central portion between the both end portions of the radio wave transmissive body.

Description

    TECHNICAL FIELD
  • The present invention relates to an antenna device and a method of mounting an antenna device.
    • BACKGROUND ART
  • In recent years, various antennas have been developed as vehicle-to-everything (V2X) antennas. In one example, the V2X antenna includes a square radiating element and parasitic elements that are disposed outside two opposing sides of the radiation element and have elongated rectangular shapes along the two opposing sides. As described in Patent Document 1, for example, the V2X antenna is disposed on at least one of a windshield or a rear window of a vehicle such as an automobile.
    • RELATED DOCUMENT PATENT DOCUMENT
  • Patent Document 1: International Publication No. WO2019/073667
    • SUMMARY OF THE INVENTION TECHNICAL PROBLEM
  • Some communications, such as V2X communication, should be able to provide stable communications in any of front, rear, left, and right directions of the vehicle. In other words, the antenna system for some communications, such as V2X communication, should be omnidirectional. As described in Patent Document 1, the antenna may be disposed on the windshield and the rear window. However, even when the antennas are disposed on the windshield and the rear window, it can sometimes be difficult to achieve sufficient gain in the left-right direction of the vehicle. In other words, ensuring directivity over a wide range around the vehicle can be difficult, even when the antennas are disposed on the windshield and the rear window. To ensure the wide range of directivity, antennas may be added to both left and right sides of the vehicle. However, adding antennas to both left and right sides of the vehicle may require extra antennas and processing units, which would increase costs.
  • An example of the object of the present invention is to ensure directivity over a wide range with a small number of antennas. Other objects of the present invention will become apparent from the description of the present specification.
    • SOLUTION TO PROBLEM
  • An aspect of the present invention is an antenna device including:
    • an antenna to radiate radio waves toward a radio wave transmissive body, the radio wave transmissive body including both end portions opposite to each other, the radio wave transmissive body being inclined at a predetermined angle with respect to a predetermined direction between the both end portions from one side to the other side in the predetermined direction, the radio waves being radiated from the other side,
    • in which a portion of the radio wave transmissive body that overlaps a projected image of the antenna in the predetermined direction is displaced to a side on which an end portion of the both end portions on the one side of the radio wave transmissive body is positioned with respect to a central portion between the both end portions of the radio wave transmissive body.
  • Another aspect of the present invention is a method of mounting an antenna device, including:
    • positioning an antenna to radiate radio waves toward a radio wave transmissive body, the radio wave transmissive body including both end portions opposite to each other, the radio wave transmissive body being inclined at a predetermined angle with respect to a predetermined direction between the both end portions from one side to the other side in the predetermined direction, the radio waves being radiated from the other side,
    • in which a portion of the radio wave transmissive body that overlaps a projected image of the antenna in the predetermined direction is displaced to a side on which an end portion of the both end portions on the one side of the radio wave transmissive body is positioned with respect to a central portion between the both end portions of the radio wave transmissive body.
  • According to the above aspect of the present invention, the directivity can be ensured over a wide range with a small number of antennas.
    • BRIEF DESCRIPTION OF THE DRAWINGS
    • [FIG. 1A] A top view of a vehicle on which an antenna device according to an embodiment is mounted.
    • [FIG. 1B] A view of a windshield and its surroundings of the vehicle on which the antenna device according to the embodiment is mounted as viewed from the left direction of the vehicle.
    • [FIG. 1C] A view of a rear window and its surroundings of the vehicle on which the antenna device according to the embodiment is mounted as viewed from the left direction of the vehicle.
    • [FIG. 2] A perspective view showing a configuration example of a front antenna according to the embodiment.
    • [FIG. 3A] A directivity gain diagram in a horizontal plane when an antenna device according to a first example is mounted on the vehicle.
    • [FIG. 3B] A directivity gain diagram in a horizontal plane when an antenna device according to comparative example is mounted on the vehicle.
    • [FIG. 4] A top view of a vehicle on which the antenna device according to the comparative example is mounted.
    • [FIG. 5A] A directivity gain diagram in a horizontal plane when the front antenna overlaps the upper end portion, the central portion, or the lower end portion of the windshield in the front-rear direction of the vehicle.
    • [FIG. 5B] A directivity gain diagram in a vertical plane when the front antenna overlaps the upper end portion, the central portion, or the lower end portion of the windshield in the front-rear direction of the vehicle.
    • [FIG. 6A] A diagram showing a configuration of a part of a vehicle with a front conductor on the lower front side of the front antenna.
    • [FIG. 6B] A diagram showing a configuration of a part of the vehicle without the front conductor on the lower front side of the front antenna.
    • [FIG. 7A] A directivity gain diagram in a horizontal plane with and without the front conductor on the lower front side of the front antenna.
    • [FIG. 7B] A directivity gain diagram in a vertical plane with and without the front conductor on the lower front side of the front antenna.
    • [FIG. 8] A diagram showing a model example of the front conductor at different angles with respect to the horizontal direction.
    • [FIG. 9A] A directivity gain diagram in a horizontal plane of the front conductor at different angles with respect to the horizontal direction.
    • [FIG. 9B] A directivity gain diagram in a vertical plane of the front conductor at different angles with respect to the horizontal direction.
    • [FIG. 10A] A view showing a first example of a rear conductor according to the embodiment.
    • [FIG. 10B] A view showing a second example of the rear conductor according to the embodiment.
    • [FIG. 11] A view of arrangement of a black ceramic of the windshield and the front antenna as viewed from the left direction of a vehicle.
    • [FIG. 12] A view of the front antenna, the windshield, and the black ceramic as viewed from the front side of a vehicle.
    • [FIG. 13] A view of the arrangement of the front antenna and the windshield as viewed from the left direction of the vehicle.
    DESCRIPTION OF EMBODIMENTS
  • Hereinafter, embodiments and variants of the present invention will be described with reference to the drawings. In all drawings, the same constituent elements are denoted by the same reference signs, and the description thereof will not be repeated.
  • In the present specification, terms of approximation such as "generally", "about", and "substantially", when used to qualify a shape, a position, or a numerical value, or other status of an element, indicate the extent to which those skilled in the art would understand that the intended purpose can be achieved by that status. For example, the term "generally parallel" may, depending on the context, include not only perfectly parallel but also a state deviating from perfectly parallel by a given angular range.
  • The X direction, the Y direction, and the Z direction are defined to describe directions. The Z direction is a direction parallel to a vertical direction. The X direction is one of horizontal directions perpendicular to the Z direction. The Y direction is one of the horizontal directions perpendicular to the Z direction and the X direction. In the embodiment, the X direction is a front-rear direction, the Y direction is a left-right direction, and the Z direction is an up-down direction. In the embodiment, directions indicated by arrows of each of the X-axis, the Y-axis, and the Z-axis are defined as a front direction, a left direction, and an upper direction, respectively. In FIG. 1A, FIG. 1B, FIG. 1C, FIG. 4, FIG. 6A, FIG. 6B, FIG. 8, FIG. 10A, FIG. 10B, FIG. 11, FIG. 12, and FIG. 13, the white circle with the black dot indicating the X-axis, the Y-axis, or the Z-axis indicates that the arrow indicated by the white circle points to the front side of the paper surface.
  • FIG. 1A is a top view of a vehicle 50 on which an antenna device 1 according to the embodiment is mounted. FIG. 1B is a view of a windshield 510 and its surroundings of a vehicle 50 on which the antenna device 1 according to the embodiment is mounted as viewed from the left direction of the vehicle 50. FIG. 1C is a view of a rear window 520 and its surroundings of the vehicle 50 on which the antenna device 1 according to the embodiment is mounted as viewed from the left direction of the vehicle 50. FIG. 1A shows the mounting position of the antenna device 1 according to the embodiment on the vehicle 50. Hereinafter, descriptions with reference to FIGS. 1A to 1C are related not only to the antenna device 1 according to the embodiment but also to a method of mounting the antenna device 1 according to the embodiment.
  • As shown in FIG. 1A, the antenna device 1 according to the embodiment includes a front antenna 10A and a rear antenna 10B. As a result, the front antenna 10A can ensure the directivity in front and both left and right directions of the vehicle 50 and the rear antenna 10B can ensure the directivity in rear and both left and right directions of the vehicle 50. The front antenna 10A and the rear antenna 10B are positioned on opposite sides to each other in the X direction. As a result, the antenna device 1 can have an omnidirectional directivity by the front antenna 10A and the rear antenna 10B. That is, the directivity can be ensured over a wide range, as compared with the case where only one of the front antenna 10A and the rear antenna 10B is used. However, the antenna device 1 may not include both the front antenna 10A and the rear antenna 10B and may include only one of the front antenna 10A or the rear antenna 10B. Alternatively, the antenna device 1 may further include an additional antenna corresponding to the front antenna 10A or the rear antenna 10B, in addition to at least one of the front antenna 10A or the rear antenna 10B. The additional antenna may be disposed in glass different from the windshield 510 and the rear window 520, such as a side glass or a rear quarter glass or a component of the vehicle 50, such as a spoiler, a bumper, a pillar, or a roof 502, for example. The glass on which the additional antenna is disposed is a dielectric such as a radio wave transmissive body or a light transmissive body. The additional antenna is disposed from the viewpoint of design of the vehicle 50, preventing obstruction of the field of view from the inside of the vehicle 50, and so on.
  • The front antenna 10A and the rear antenna 10B according to the embodiment are vehicle-to-everything (V2X) antennas. However, the front antenna 10A and the rear antenna 10B may be other antennas such as dedicated short range communications (DSRC), electronic toll collection (ETC), WiFi (registered trademark), Bluetooth (registered trademark), global navigation satellite system (GNSS), fifth generation mobile communication system (5G), and long term evolution (LTE). At least one of transmission or reception of radio waves of the front antenna 10A is performed by antenna elements covered by a front antenna case 110A, for example, which will be described later with reference to FIG. 2. The same applies to the transmission and reception of radio waves of the rear antenna 10B.
  • In the embodiment, the front antenna 10A and the rear antenna 10B are the same antenna. As a result, the directivity characteristics, the angle at half maximum, the supported frequency, and the supported medium of the front antenna 10A are the same as the directivity characteristics, the angle at half maximum, the supported frequency, and the supported medium of the rear antenna 10B. However, the directivity characteristics, the angle at half maximum, the supported frequency, and the supported medium of the front antenna 10A and the directivity characteristics, the angle at half maximum, the supported frequency, and the supported medium of the rear antenna 10B may be different from each other.
  • In FIG. 1A, FIG. 1B, and FIG. 1C, the front antenna 10A and the rear antenna 10B are schematically illustrated as antenna cases having a generally rectangular parallelepiped shape that accommodates antenna elements such as patch antennas. Hereinafter, unless otherwise specified, in each drawing, the front antenna 10A and the rear antenna 10B are schematically illustrated as antenna cases having a generally rectangular parallelepiped shape. The antenna cases having a generally rectangular parallelepiped shape of the front antenna 10A and the rear antenna 10B have the same configuration as a front antenna case 110A described later with reference to FIG. 2, for example.
  • The vehicle 50 according to the embodiment is a sedan type automobile. However, the vehicle 50 may be any type of automobile. For example, the vehicle 50 may be an automobile other than a sedan type, such as a van type or a sport utility vehicle (SUV) type. Hereinafter, unless otherwise specified, the vehicle 50 according to the embodiment will be described as a sedan type automobile.
  • As shown in FIG. 1A, the vehicle 50 according to the embodiment includes a body 500, a windshield 510, and a rear window 520. The body 500 has a roof 502, a hood 504, and a trunk lid 506. The roof 502 is not particularly limited, but is, for example, a steel plate roof, a glass roof, a resin roof, a carbon roof, or a combination thereof. The hood 504 and the trunk lid 506 are, for example, conductive sheet metals made of materials such as aluminum and steel. However, a part of the hood 504 and the trunk lid 506 may be made of a resin part. A hatchback may be used instead of the trunk lid 506. The roof 502 is positioned generally at the central portion of the body 500 in the X direction as viewed in the Z direction. The hood 504 is positioned at the front portion of the body 500 in the X direction as viewed in the Z direction. The windshield 510 is positioned between the front end of the roof 502 and the rear end of the hood 504 in the X direction as viewed in the Z direction. The windshield 510 is a dielectric. Specifically, the windshield 510 is a radio wave transmissive body that transmits radio waves between the interior of the vehicle 50 and the space in front of the vehicle 50. The windshield 510 is also a light transmissive body that transmits light such as visible light between the interior of the vehicle 50 and the space in front of the vehicle 50. The trunk lid 506 is positioned at the rear portion of the body 500 in the X direction as viewed in the Z direction. The rear window 520 is positioned between the rear end of the roof 502 and the front end of the trunk lid 506 in the X direction as viewed from the Z direction. The rear window 520 is a dielectric. Specifically, the rear window 520 is a radio wave transmissive body that transmits radio waves between the inside of the vehicle 50 and the space behind the vehicle 50. The rear window 520 is also a light transmissive body that transmits light such as visible light between the vehicle interior of the vehicle 50 and the space behind the vehicle 50.
  • As shown in FIG. 1B, the front antenna 10A is disposed such that the radiation surface, from which radio waves of the front antenna 10A are radiated, is directed forward the vehicle 50. In the example shown in FIG. 1B, the radiation surface of the front antenna 10A is a front surface of the front antenna 10A. The type of the antenna of the front antenna 10A is not particularly limited. For example, the front antenna 10A may be a patch antenna, a dipole type antenna or any other type of antenna. The windshield 510 is disposed in front of the radiation surface of the front antenna 10A. That is, the front antenna 10A is disposed behind the windshield 510. Accordingly, the front antenna 10A is disposed on the inside of the vehicle with respect to the windshield 510. As a result, the front antenna 10A radiates radio waves toward the windshield 510. The hood 504 is positioned on the lower front side of the front antenna 10A. In one example, the front antenna 10A is fixed to the rear surface of the windshield 510. The rear surface of the windshield 510 is a surface of the windshield 510 on the inside of the vehicle. In another example, the front antenna 10A may be disposed above or inside a dashboard positioned between the lower end of the windshield 510 and the rear end of the hood 504. The front antenna 10A may be disposed while it is covered with a resin cover along with other electrical equipment.
  • Hereinafter, as necessary, a portion of the windshield 510 that overlaps with the projected image of the front antenna 10A in the X direction is referred to as a front overlapping portion 510a. As shown in FIG. 1B, the image of the front antenna 10A is formed by projecting the antenna case of the front antenna 10A having a generally rectangular parallelepiped shape toward the windshield 510 in parallel with the X direction. In FIG. 1B, the two broken lines for indicating the front overlapping portion 510a extend from the upper surface and the lower surface of the front antenna 10A toward the front. The front overlapping portion 510a is a portion of the windshield 510 positioned between the two broken lines. The same applies to the front overlapping portion 510a shown in FIG. 6A, FIG. 6B, FIG. 8, FIG. 11, and FIG. 13 which will be described later.
  • As shown in FIG. 1A, the front overlapping portion 510a is positioned generally at the central portion of the windshield 510 in the left-right direction as viewed from the Z direction. However, the front overlapping portion 510a may be at a position deviated in the Y direction from generally the center of the windshield 510 in the left-right direction if other electrical equipment such as a wiper, a sensor, and a drive recorder, or black ceramic is present near the front antenna 10A.
  • As shown in FIG. 1B, the windshield 510 is inclined at a predetermined angle with respect to the X direction between the lower end portion and the upper end portion of the windshield 510 as viewed from the Y direction. Specifically, as viewed from the Y direction, the windshield 510 is inclined obliquely upward from the rear end of the hood 504 toward the front end of the roof 502. Accordingly, the lower end portion of the windshield 510 is displaced forward with respect to the upper end portion of the windshield 510 in the X direction and the upper end portion of the windshield 510 is displaced backward with respect to the lower end portion of the windshield 510 in the X direction as viewed from the Y direction. As viewed in the Y direction, the front overlapping portion 510a is displaced to a side where the lower end portion of the windshield 510 is positioned with respect to the central portion between the upper end portion and the lower end portion of the windshield 510. Specifically, the front overlapping portion 510a is positioned at the lower end portion of the windshield 510. However, the front overlapping portion 510a may be at a position deviated from the lower end portion of the windshield 510 as appropriate if other electrical equipment such as a wiper, a sensor, and a drive recorder, or black ceramic is present near the front antenna 10A.
  • As shown in FIG. 1C, the rear antenna 10B is disposed such that the radiation surface, from which radio waves of the rear antenna 10B are radiated, is directed backward the vehicle 50. In the example shown in FIG. 1C, the radiation surface of the rear antenna 10B is a rear surface of the rear antenna 10B. The type of the antenna of the rear antenna 10B is not particularly limited. For example, the rear antenna 10B may be a patch antenna, a dipole type antenna or any other type of antenna. The rear window 520 is disposed behind the radiation surface of the rear antenna 10B. That is, the rear antenna 10B is disposed in front of the rear window 520. Accordingly, the rear antenna 10B is disposed on the inside of the vehicle with respect to the rear window 520. As a result, the rear antenna 10B radiates radio waves toward the rear window 520. The trunk lid 506 is positioned on the lower rear side of the rear antenna 10B. In one example, the rear antenna 10B is fixed to the front surface of the rear window 520. The front surface of the rear window 520 is a surface of the rear window 520 on the inside of the vehicle. In another example, the rear antenna 10B may be disposed above or inside a rear parcel shelf positioned between the lower end of the rear window 520 and the front end of the trunk lid 506. The rear antenna 10B may be positioned while it is covered with a resin cover along with other electrical equipment.
  • Hereinafter, as necessary, a portion of the rear window 520 that overlaps with the projected image of the rear antenna 10B in the X direction is referred to as a rear overlapping portion 520a. As shown in FIG. 1C, the image of the rear antenna 10B is formed by projecting the antenna case of the rear antenna 10B having a generally rectangular parallelepiped shape toward the rear window 520 in parallel with the X direction. In FIG. 1C, the two broken lines for indicating the rear overlapping portion 520a extend backward from the upper surface and the lower surface of the rear antenna 10B. The rear overlapping portion 520a is a portion of the rear window 520 positioned between the two broken lines. The same applies to a rear overlapping portion 520a shown in FIG. 10A and FIG. 10B which will be described later.
  • As shown in FIG. 1A, the rear overlapping portion 520a is positioned generally at the central portion of the rear window 520 in the left-right direction as viewed from the Z direction. However, the rear overlapping portion 520a may be at a position deviated in the Y direction from generally the center of the rear window 520 in the left-right direction if other electrical components such as a wiper, a sensor, and a drive recorder, or black ceramic is present near the rear antenna 10B.
  • As shown in FIG. 1C, the rear window 520 is inclined at a predetermined angle with respect to the X direction between the lower end portion and the upper end portion of the rear window 520 as viewed from the Y direction. Specifically, as viewed from the Y direction, the rear window 520 is inclined obliquely upward from the front end of the trunk lid 506 toward the rear end of the roof 502. Accordingly, the lower end portion of the rear window 520 is displaced backward with respect to the upper end portion of the rear window 520 in the X direction and the upper end portion of the rear window 520 is displaced forward with respect to the lower end portion of the rear window 520 in the X direction as viewed in the Y direction. As viewed in the Y direction, the rear overlapping portion 520a is displaced to a side where the lower end portion of the rear window 520 is positioned with respect to the central portion between the upper end portion and the lower end portion of the rear window 520. Specifically, the rear overlapping portion 520a is positioned at the lower end portion of the rear window 520. However, the rear overlapping portion 520a may be at a position deviated from the lower end portion of the rear window 520 as appropriate if other electrical equipment such as a wiper, a sensor, and a drive recorder, or black ceramic is present near the rear antenna 10B.
  • FIG. 2 is a perspective view showing a configuration example of the front antenna 10A according to the embodiment. The descriptions regarding the front antenna 10A using FIG. 2 can also be applied to the rear antenna 10B. The configurations of the front antenna 10A and the rear antenna 10B are not limited to the configuration example shown in FIG. 2.
  • As shown in FIG. 2, the front antenna 10A includes a front antenna case 110A and a front cable 120A.
  • The front antenna case 110A has a generally rectangular parallelepiped shape. The front antenna case 110A covers the antenna element, not illustrated in FIG. 2. This antenna element is a patch antenna, for example. However, the antenna covered by the front antenna case 110A is not limited to the patch antenna. The front antenna case 110A is radio wave transmissive. The front antenna case 110A is made of a resin, for example. The front antenna case 110A is provided with an attachment structure. The front antenna case 110A is fixed to a fixing structure such as a bracket provided to the vehicle 50 via the mounting structure.
  • The front cable 120A is drawn from the front antenna case 110A. The front cable 120A is electrically connected to the antenna element covered by the front antenna case 110A. A signal obtained from the antenna element covered by the front antenna case 110A is output through the front cable 120A. However, the method of outputting the signal obtained from the antenna element is not limited to the method using the front cable 120A. For example, a substrate such as a printed circuit board (PCB) on which the antenna element is mounted and a connector such as a coaxial connector may be electrically connected to each other. When the substrate and the connector are electrically connected to each other, a signal obtained from the antenna element is output via the substrate and the connector.
  • FIG. 3A is a directivity gain diagram in a horizontal plane when the antenna device 1 according to a first example is mounted on the vehicle 50. FIG. 3B is a directivity gain diagram in a horizontal plane when the antenna device 1K according to a comparative example is mounted on the vehicle 50. FIG. 4 is a top view of a vehicle 50 on which an antenna device 1K according to the comparative example is mounted. In Example 1 and the comparative example, unless otherwise specified, the horizontal plane is a plane perpendicular to the Z direction.
  • The antenna device 1 according to the first example is an example of the antenna device 1 according to the embodiment. In the first example, the front overlapping portion 510a is positioned at the lower end portion of the windshield 510. In the first example, the rear overlapping portion 520a is positioned at the lower end portion of the rear window 520. In the first example, the front antenna 10A and the rear antenna 10B are the same antenna. That is, the angle at half maximum of the single characteristic of the front antenna 10A and the angle at half maximum of the single characteristic of the rear antenna 10B are the same.
  • The antenna device 1K according to the comparative example will be described with reference to FIG. 4. The antenna device 1K according to the comparative example is the same as the antenna device 1 according to the first example except for the following points.
  • The front antenna 10A according to the first example and the front antenna 10A according to the comparative example are the same antenna. The front overlapping portion 510aK according to the comparative example is positioned at the central portion of the windshield 510 in the left-right direction in the same way as the front overlapping portion 510a according to the first example as viewed in the Z direction. The front overlapping portion 510aK according to the comparative example differs from the front overlapping portion 510a according to the first example in that it is positioned at the central portion between the upper end portion and the lower end portion of the windshield 510 as viewed in the Y direction.
  • The rear antenna 10B according to the first example and the rear antenna 10B according to the comparative example are the same antenna. The rear overlapping portion 520aK according to the comparative example is positioned at the central portion of the rear window 520 in the left-right direction in the same way as the rear overlapping portion 520a according to the first example as viewed in the Z direction. The rear overlapping portion 520aK according to the comparative example differs from the rear overlapping portion 520a according to the first example in that it is positioned in the central portion between the upper end portion and the lower end portion of the rear window 520 as viewed in the Y direction.
  • The directivity gain in the horizontal plane of the antenna device 1 according to the first example and the antenna device 1K according to the comparative example will be described with reference to FIGS. 3A and 3B.
  • The numbers attached to the outer periphery of the gain diagrams of FIGS. 3A and 3B indicate directions (unit: °). The numbers from the center to 270° direction of the gain diagrams of FIGS. 3A and 3B indicate gains (unit: dBi). In FIGS. 3A and 3B, 0° direction is the front side of the vehicle 50, 180° direction is the rear side of the vehicle 50, 90° direction is the left side of the vehicle 50, and 270° direction is the right side of the vehicle 50. The solid line pattern in FIG. 3A shows the directivity gain in the horizontal plane of the front antenna 10A according to the first example. The broken line pattern of FIG. 3A shows the directivity gain in the horizontal plane of the rear antenna 10B according to the first example. The solid line pattern in FIG. 3B shows the directivity gain in the horizontal plane of the front antenna 10A according to the comparative example. The broken line pattern in FIG. 3B shows the directivity gain in the horizontal plane of the rear antenna 10B according to the comparative example.
  • The gain of the front antenna 10A according to the first example in the 90° direction is -1.58 dBi. The gain of the front antenna 10A according to the comparative example in the 90° direction, on the other hand, is -12.15 dBi. Accordingly, it can be seen that the gain of the front antenna 10A according to the first example in the 90° direction is significantly increased as compared with the gain of the front antenna 10A according to the comparative example in the 90° direction. Accordingly, even if the front antenna 10A according to the first example and the front antenna 10A according to the comparative example are the same antenna, the width at half maximum of the front antenna 10A can be widened and the gain of the front antenna 10A in the left-right direction of the vehicle 50 can be improved by changing the mounting position of the front antenna 10A.
  • The gain of the rear antenna 10B according to the first example in the 90° direction is -1.53 dBi. The gain of the rear antenna 10B according to the comparative example in the 90° direction, on the other hand, is -11.24 dBi. Accordingly, it can be seen that the gain of the rear antenna 10B according to the first example in the 90° direction is significantly increased as compared with the gain of the rear antenna 10B according to the comparative example in the 90° direction. Accordingly, even if the rear antenna 10B according to the first example and the rear antenna 10B according to the comparative example are the same antenna, the width at half maximum of the rear antenna 10B can be widened and the gain of the rear antenna 10B in the left-right direction of the vehicle 50 can be improved by changing the mounting position of the rear antenna 10B.
  • In FIG. 3A, the difference between the maximum value and the minimum value of the gain of the front antenna 10A at 0° or more and 90° or less and 270° or more and less than 360° and the gain of the rear antenna 10B at 90° or more and 270° or less is 8.21 dB. In FIG. 3B, on the other hand, the difference between the maximum value and the minimum value of the gain of the front antenna 10A at 0° or more and 90° or less and 270° or more and less than 360° and the gain of the rear antenna 10B at 90° or more and 270° or less is 16.02 dB. Therefore, the ripple is reduced in the first example as compared with the comparative example. Accordingly, it can be seen that the antenna device 1 according to the first example ensures the directivity over a wider range than the antenna device 1K according to the comparative example. In particular, the antenna device 1 according to the first example can have an omnidirectional directivity.
  • In the first example, the angle at half maximum of the single characteristic of the front antenna 10A and the angle at half maximum of the single characteristic of the rear antenna 10B are the same. However, the angle at half maximum of the single characteristic of the front antenna 10A and the angle at half maximum of the single characteristic of the rear antenna 10B may be different from each other. When the angle at half maximum of the single characteristics of the front antenna 10A and the angle at half maximum of the single characteristics of the rear antenna 10B are different from each other, for example, the angles at half maximum of the front antenna 10A and the rear antenna 10B can be determined such that the directivity gain in the horizontal plane of the front antenna 10A and the rear antenna 10B combined has omnidirectional directivity.
  • Next, the technical basic requirements of the antenna device 1 according to the embodiment and the first example will be described.
  • The radiation characteristics of the front antenna 10A when the windshield 510 is present in front of the radiation surface of the front antenna 10A will be described. The closer the incidence angle of the radio waves radiated from the front antenna 10A to the rear surface of the windshield 510 is to 0°, the less likely the radio waves radiated from the front antenna 10A are to be scattered on the rear surface of the windshield 510, and the more likely the radio waves are to be transmitted through the windshield 510 and the higher the gain will be. The closer the incidence angle of the radio waves radiated from the front antenna 10A to the rear surface of the windshield 510 is to the right angle, on the other hand, the more likely the radio waves radiated from the front antenna 10A are to be scattered on the rear surface of the windshield 510, and the less likely the radio waves are to be transmitted through the windshield 510 and the lower the gain will be. In the comparative example, the front antenna 10A overlaps with the central portion between the upper end portion and the lower end portion of the windshield 510 in the front-rear direction of the vehicle 50. In the embodiment and the first example, on the other hand, the front antenna 10A overlaps with the lower end portion of the windshield 510 in the front-rear direction of the vehicle 50. Accordingly, the irradiation area of the radio waves radiated forward and downward from the front antenna 10A to the rear surface of the windshield 510 in the embodiment and the first example can be smaller than the irradiation area of the radio waves radiated forward and downward from the front antenna 10A to the rear surface of the windshield 510 in the comparative example. Therefore, the scattering of the radio waves radiated forward and downward from the front antenna 10A to the rear surface of the windshield 510 can be reduced in the embodiment and the first example as compared with the comparative example. Accordingly, the gain of the embodiment and the first example can be higher than the gain of the comparative example by reducing the scattering of the radio waves on the rear surface of the windshield 510.
  • FIG. 5A is a directivity gain diagram in a horizontal plane when the front antenna 10A overlaps the upper end portion, the central portion, or the lower end portion of the windshield 510 in the front-rear direction of the vehicle 50. Unless otherwise specified, in the description using FIG. 5A, the central portion of the windshield 510 is a central portion between the upper end portion and the lower end portion of the windshield 510 as viewed in the Y direction with reference to FIG. 1B. In FIG. 5A, 0° direction is the front side of the vehicle 50, 180° direction is the rear side of the vehicle 50, 90° direction is the left side of the vehicle 50, and 270° direction is the right side of the vehicle 50. In FIG. 5A, the windshield 510 is disposed on the 0° direction side of the front antenna 10A. The dotted line pattern, the broken line pattern, and the solid line pattern in FIG. 5A show the directivity gains in the horizontal plane when the front antenna 10A overlaps the upper end portion, the central portion, and the lower end portion of the windshield 510 in the X direction respectively. In FIG. 5A, the gains in the 90° direction when the front antenna 10A overlaps the upper end portion, the central portion, and the lower end portion of the windshield 510 in the X direction are -11.99 dBi, -12.15 dBi, and -1.58 dBi, respectively. There is little difference between the gain in the 90° direction when the front antenna 10A overlaps the upper end portion of the windshield 510 in the X direction and the gain in the 90° direction when the front antenna 10A overlaps the central portion of the windshield 510 in the X direction. It can be seen, on the other hand, the closer the front overlapping portion 510a is to the lower end of the windshield 510, the higher the directivity gain of the vehicle 50 in the left-right direction is.
  • FIG. 5B is a directivity gain diagram in a vertical plane when the front antenna 10A overlaps the upper end portion, the central portion, or the lower end portion of the windshield 510 in the front-rear direction of the vehicle 50. Unless otherwise specified, in the description using FIG. 5B, the central portion of the windshield 510 is a central portion between the upper end portion and the lower end portion of the windshield 510 as viewed in the Y direction with reference to FIG. 1B. In FIG. 5B, 90° direction is the front side of the vehicle 50, -90° direction is the rear side of the vehicle 50, 0° direction is the upper side of the vehicle 50, and 180° direction is the lower side of the vehicle 50. In FIG. 5B, the windshield 510 is disposed on the 90° direction side of the front antenna 10A. The dotted line pattern, the broken line pattern, and the solid line pattern in FIG. 5B show the directivity gains in the horizontal plane when the front antenna 10A overlaps the upper end portion, the central portion, and the lower end portion of the windshield 510 in the X direction respectively. In FIG. 5B, it can be seen that the gain deviation (the difference between the maximum value and the minimum value of the gain) in the range of 60° to 120° decreases as the front overlapping portion 510a goes from the upper end to the lower end of the windshield 510. That is, the gain of the front antenna 10A is higher when the front antenna 10A overlaps the lower end portion of the windshield 510 in the X direction than when the front antenna 10A overlaps the upper end portion of the windshield 510 in the X direction. The reason is that when the front antenna 10A overlaps the lower end portion of the windshield 510 in the X direction, the irradiation area of the radio waves radiated forward and downward from the front antenna 10A to the rear surface of the windshield 510 is smaller and the radio waves can be less likely to be scattered on the rear surface of the windshield 510, rather than when the front antenna 10A overlaps the upper end portion of the windshield 510 in the X direction.
  • In the first example, the front antenna 10A overlaps the lower end portion of the windshield 510 in the X direction. Therefore, the directivity can be stably ensured over a wide range in the first example compared to the case where the front antenna 10A overlaps the upper end portion or the central portion of the windshield 510 in the X direction. The ensuring of the directivity over a wide range in the first example can be realized without adding antennas on both left and right sides of the vehicle 50. Therefore, the directivity can be ensured over a wide range with a small number of antennas in the first example. The stable ensuring of the directivity over a wide range in the first example can be better as the angle at half maximum of the front antenna 10A increases.
  • As viewed in the Y direction, the front overlapping portion 510a may be positioned at a portion positioned forward from the central portion of the windshield 510 in the Z direction by a predetermined distance, instead of the lower end portion of the windshield 510. When the front overlapping portion 510a is positioned forward from the central portion of the windshield 510 in the Z direction as viewed from the Y direction, the directivity can be ensured over a wide range with a small number of antennas as compared with the case where the front overlapping portion 510a is positioned at the central portion of the windshield 510 in the Z direction or the upper end portion of the windshield 510 as viewed from the Y direction.
  • The descriptions regarding the front antenna 10A using FIG. 3A, FIG. 3B, FIG. 4, FIG. 5A, and FIG. 5B can be also applied to the rear antenna 10B.
  • Next, the characteristics of propagation of radio waves radiated from the front antenna 10A or the rear antenna 10B through the conductor will be described. The embodiment and the first example use the characteristics of the propagation of the radio waves radiated from the front antenna 10A or the rear antenna 10B through the conductor-made sheet metal, such as the hood 504 and the trunk lid 506. Embodiment 1 and the first example ensures the gain of the antenna device 1 in the left-right direction of the vehicle 50 by using the characteristic that the radio waves radiated from each antenna propagate through the conductor. A hatchback may be used instead of the trunk lid 506 as the conductor used for the propagation of the radio waves. The hatchback can also be used for radio wave propagation in the same way as the trunk lid 506.
  • FIG. 6A is a diagram showing a configuration of a part of the vehicle 50 with a front conductor 500a on the lower front side of the front antenna 10A. FIG. 6B is a diagram showing a configuration of a part of the vehicle 50 without the front conductor 500a on the lower front side of the front antenna 10A. FIGS. 6A and 6B show a comparative configuration of the presence or absence of a front conductor 500a on the lower front side of the front antenna 10A. In the example shown in FIG. 6A, the hood 504 is the front conductor 500a. In the example shown in FIG. 6A, the front conductor 500a is disposed in front of the lower end portion of the windshield 510 as viewed from the Y direction. Specifically, the front conductor 500a extends frontward and downward from the lower end portion of the windshield 510 as viewed from the Y direction.
  • FIG. 7A is a directivity gain diagram in a horizontal plane with and without the front conductor 500a on the lower front side of a front antenna 10A. The relationship between the numbers attached to the outer periphery of the gain diagram and the directions indicated by the numbers in FIG. 7A is the same as the relationship between the numbers attached to the outer periphery of the gain diagram and the directions indicated by the numbers in FIG. 5A. In FIG. 7A, the broken line pattern shows the directivity gain in the horizontal plane when the front conductor 500a is provided on the lower front side of the front antenna 10A as shown in FIG. 6A. In FIG. 7A, the solid line pattern indicates the directivity gain in the horizontal plane when the front conductor 500a is not provided on the lower front side of the front antenna 10A as shown in FIG. 6B.
  • FIG. 7B is a directivity gain diagram in a vertical plane with and without a front conductor 500a on the lower front side of the front antenna 10A. The relationship between the numbers attached to the outer periphery of the gain diagram and the directions indicated by the numbers in FIG. 7B is the same as the relationship between the numbers attached to the outer periphery of the gain diagram and the directions indicated by the numbers in FIG. 5B. In FIG. 7B, the broken line pattern indicates the directivity gain in the vertical plane when the front conductor 500a is provided on the lower front side of the front antenna 10A as shown in FIG. 6A. In FIG. 7B, the solid line pattern indicates the directivity gain in the vertical plane when the front conductor 500a is not provided on the lower front side of the front antenna 10A as shown in FIG. 6B.
  • As shown in FIG. 7A, the directivity gain in the horizontal plane is almost the same regardless of the presence or absence of the front conductor 500a. In the directivity gain in the vertical plane, on the other hand, as shown in FIG. 7B, the gain deviation (the difference between the maximum value and the minimum value of the gain) in the range of 60° to 120° in front of the radiation direction of the front antenna 10A is reduced when the front conductor 500a is provided as compared with when the front conductor 500a is not provided. That is, even if the radiation direction of the radio waves from the front antenna 10A is close to parallel with the rear surface of the windshield 510 on the lower front side of the radiation surface of the front antenna 10A, the radio waves radiated from the front antenna 10A can propagate on the upper surface of the front conductor 500a disposed on the front side (outside as viewed from the inside of the vehicle cabin) with respect to the windshield 510. For this reason, the gain of the front antenna 10A can be ensured in the left-right direction of the vehicle 50 as compared with the case where the front conductor 500a is not provided. The ensuring of the gain of the front antenna 10A in the left-right direction of the vehicle 50 can be better as the angle at half maximum of the front antenna 10A increases.
  • The descriptions regarding the front antenna 10A using FIG. 6A, FIG. 6B, FIG. 7A, and FIG. 7B can also be applied to the rear antenna 10B.
  • Next, the shape of each of the hood 504 and the trunk lid 506 will be described.
  • The verification results of the inventors demonstrate that the angles of the hood 504 and the trunk lid 506 with respect to the X direction affect the radiation characteristics of the front antenna 10A and the rear antenna 10B.
  • FIG. 8 is a diagram showing a model example of the front conductor 500a at different angles with respect to the horizontal direction. In the example shown in FIG. 8, as indicated by the arrow attached near the front conductor 500a, the front end of the front conductor 500a is movable downward about the portion of the front conductor 500a near the lower end of the windshield 510.
  • FIG. 9A is a directivity gain diagram in a horizontal plane of the front conductor 500a at different angles with respect to the horizontal direction. FIG. 9B is a directivity gain diagram in a vertical plane of the front conductor 500a at different angles with respect to the horizontal direction. The relationship between the numbers attached to the outer periphery of the gain diagram and the directions indicated by the numbers in FIG. 9A is the same as the relationship between the numbers attached to the outer periphery of the gain diagram and the directions indicated by the numbers in FIG. 5A. The relationship between the numbers attached to the outer periphery of the gain diagram and the directions indicated by the numbers in FIG. 9B is the same as the relationship between the numbers attached to the outer periphery of the gain diagram and the directions indicated by the numbers in FIG. 5B.
  • In FIG. 9A and FIG. 9B, the front end of the front conductor 500a is inclined downward by 30°, 60°, or 90° around the portion of the front conductor 500a near the lower end of the windshield 510 with respect to the 0° inclination of the front conductor 500a from the X direction as shown in FIG. 8. In FIG. 9A and FIG. 9B, if the inclination of the front conductor 500a with respect to the X direction is 0°, the front conductor 500a is parallel with the X direction. The solid line pattern, the broken line pattern, the dotted line pattern, and the dash-dotted line pattern in FIG. 9A and FIG. 9B show gains when the inclinations of the front conductor 500a with respect to the X direction are 0°, 30°, 60°, and 90°, respectively.
  • As shown in FIG. 9A, it can be seen that the directivity gain in the horizontal plane of the horizontal plane at 0° or more and 90° or less and 270° or more and less than 360° is the lowest when the inclination of the front conductor 500a with respect to the X direction is 90°, and is improved as the front conductor 500a is gradually closer to the X direction. It is understood that the front conductor 500a hardly contributes to the radiation of the radio waves from the front antenna 10A when the front conductor 500a is perpendicular to the X direction. However, if the front conductor 500a is close to the X direction, the radio waves radiated from the front antenna 10A can propagate through the front conductor 500a and the gain on the front side of the front antenna 10A can be improved. For example, when the angle of the front conductor 500a with respect to the X direction is -6° (angle downward closer to the X direction), the radio wave propagates to the elevation angle of -6° and the gain in the depression angle direction from the horizontal plane is improved. Therefore, the inclination of the front conductor 500a with respect to the X direction is desirably set -30° or more and +30° or less, for example, when communicating with others by the V2X communication using the front antenna 10A. The gain of the front antenna 10A can be improved by setting the inclination of the front conductor 500a with respect to the X direction to this range.
  • As shown in FIG. 9B, it can be seen that the variation of the directivity gain in the vertical plane in the elevation angle range on the front side of the front antenna 10A, that is, the variation of the directivity gain in the vertical plane of 60° or more and less than 120° is smaller when the inclination of the front conductor 500a with respect to the X direction is 0° than when the inclination of the front conductor 500a with respect to the X direction is greater than 0°. Accordingly, the front antenna 10A can stably radiate radio waves toward the elevation angle range on the front side when the front conductor 500a is closer to the X direction.
  • The shape of the front conductor 500a is not particularly limited. For example, the shape of the front conductor 500a may be a flat plate. Alternatively, a part of the front conductor 500a may be provided with an uneven shape or an R shape. For example, the propagation characteristics of the radio waves from the horizontal plane to the lower side can be improved and the directivity gain of the depression angle can be increased by shaping the front conductor 500a inclined downward toward the front end of the body 500.
  • The descriptions regarding the front antenna 10A using FIG. 8, FIG. 9A, and FIG. 9B can be also applied to the rear antenna 10B.
  • FIG. 10A is a view showing a first example of the rear conductor 500b according to the embodiment. FIG. 10B is a view showing a second example of the rear conductor 500b according to the embodiment.
  • The rear conductor 500b shown in FIG. 10A or FIG. 10B has a hatchback or a structure similar to a hatchback. For example, the hatchback of the van is close to perpendicular to the X direction. As a result, as shown in FIG. 10A or FIG. 10B, a part of the rear conductor 500b may extend generally parallel to the X direction from the lower end portion of the rear window 520. When a part of the rear conductor 500b extends generally parallel to the X direction from the lower end portion of the rear window 520, the directivity gain in the horizontal plane of the rear antenna 10B can be improved as compared with the case where the rear conductor 500b is simply perpendicular to the X direction. In the example shown in FIG. 10A, the rear conductor 500b includes a portion generally parallel to the X direction and a portion extending from the front end of the portion generally parallel to the X direction and generally parallel to the Z direction. In the example shown in FIG. 10B, the rear conductor 500b includes a portion generally parallel to the X direction and a portion extending from the rear end of the portion generally parallel to the X direction and generally parallel to the Z direction.
  • The rear conductor 500b can be formed by various methods. For example, a part of the body 500 may be bent in an L-shape. Alternatively, the conductor generally parallel to the X direction may be added later when the conductor generally parallel to the Z direction is provided in advance. Alternatively, a spoiler may be used. The rear conductor 500b may be used as a conductor alone. Alternatively, the rear conductor 500b may be integrated with the body 500. The rear conductor 500b may be attached to the body 500 while it is provided at least one of outside or inside the resin material.
  • The descriptions regarding the rear antenna 10B using FIG. 10A and FIG. 10B can also be applied to the front antenna 10A.
  • Next, the influence of the black ceramic 512 provided on the windshield 510 and the spacing between the black ceramic 512 and the front antenna 10A will be described. The following descriptions regarding the influence of the black ceramic 512 provided on the windshield 510 and the spacing between the black ceramic 512 and the front antenna 10A are also applicable to the influence of the black ceramic provided on the rear window 520 and the spacing between the black ceramic and the rear antenna 10B.
  • Black ceramic is printed on the surface of the peripheral edge of glass such as a windshield 510 and a rear window 520. The black ceramic has a role of protecting an adhesive used when glass such as a windshield 510 and a rear window 520 is assembled to the body 500. The black ceramic generally contains alumina and titanium carbide added to alumina, as well as other substances if required. The alumina is a substance with a low dissipation factor. The titanium carbide, on the other hand, is a conductive material. For this reason, there is a possibility that some electromagnetic waves transmitted through the black ceramic flow as a current to the titanium carbide and are converted into heat. This phenomenon is the same as the behavior of dielectric loss radio wave absorbers and is a factor that inhibits radio wave transmission. Therefore, the antennas is desirably spaced apart from the black ceramic by a predetermined spacing when the antennas such as the front antenna 10A and the rear antenna 10B are disposed at the ends of the glass such as the windshield 510 and the rear window 520. Specifically, the front overlapping portion 510a and the black ceramic are desirably displaced from each other. Similarly, the rear overlapping portion 520a and the black ceramic are desirably displaced from each other.
  • FIG. 11 is a view of the black ceramic 512 of the windshield 510 and the front antenna 10A as viewed from the left direction of the vehicle 50. In FIG. 11, the front antenna 10A is illustrated as the antenna case having a generally rectangular parallelepiped shape that accommodates the antenna element.
  • In the example shown in FIG. 11, the black ceramic 512 is provided on the rear surface of the lower end of the windshield 510. The black ceramic 512 is almost impermeable to light. As a result, the portion of the lower end of the windshield 510 provided with the black ceramic 512 does not function as a light transmissive body. Accordingly, the lower end of the portion functioning as the light transmissive body of the windshield 510 is the upper end of the black ceramic 512.
  • In the example shown in FIG. 11, the front overlapping portion 510a and the black ceramic 512 are displaced from each other. The distance L from the level of the upper end of the black ceramic 512 to the lower surface of the front antenna 10A is 20 mm, for example. The distance L shown in FIG. 11 can be freely set as long as the black ceramic 512 does not interfere with the radio waves radiated from the rear antenna 10B. When the black ceramic 512 is present in the radiation direction of the radio waves of the front antenna 10A, there is a possibility that the gain of the front antenna 10A is reduced. For this reason, the front antenna 10A is spaced apart by a predetermined spacing from the black ceramic 512 in the Z direction.
  • The rear antenna 10B can also be spaced apart by a predetermined spacing from the black ceramic provided at the lower end of the rear window 520 in the same way as the front antenna 10A. The distance from the level of the upper end of the black ceramic provided at the lower end of the rear window 520 to the lower surface of the housing of the rear antenna 10B is 5 mm, for example. This distance can be freely set as long as the black ceramic does not interfere with the radio waves radiated from the rear antenna 10B.
  • FIG. 12 is a view of the front antenna 10A, the windshield 510, and the black ceramic 512 as viewed from the front of the vehicle 50. In FIG. 12, the front antenna 10A is illustrated as the antenna case having a generally rectangular parallelepiped shape that accommodates the antenna element.
  • The black ceramic 512 defines a recess portion 512a as viewed from the front. The recess portion 512a at least partially surrounds the front overlapping portion 510a as viewed from the front. Specifically, the recess portion 512a at least partially surrounds the lower end of the front antenna 10A as viewed from the front. Accordingly, the overlapping between the front antenna 10A and the black ceramic 512 in the X direction can be avoided by the recess portion 512a. Therefore, the degree of freedom of the mounting position of the front antenna 10A can be increased as compared with the case where the recess portion 512a is not provided. Accordingly, the front antenna 10A can be disposed closer to the lower end of the windshield 510 as viewed from the front and the gain of the front antenna 10A can be improved as compared with the case where the recess portion 512a is not provided.
  • The descriptions regarding the front antenna 10A, the windshield 510, and the black ceramic 512 using FIG. 12 can be also applied to the rear antenna 10B, the rear window 520, and the black ceramic provided in the rear window 520. That is, the black ceramic provided on the rear window 520 may also define a recess portion corresponding to the recess portion 512a of the black ceramic 512 provided on the windshield 510.
  • Next, the angle of the windshield 510 with respect to the X direction, the angle of the rear window 520 with respect to the X direction, the spacing between the front antenna 10A and the windshield 510, and the spacing between the rear antenna 10B and the rear window 520 will be described.
  • The angle of the windshield 510 with respect to the X direction contributes to at least one of transmission or scattering of radio waves emitted from the front antenna 10A. In particular, the reflection of radio waves by the windshield 510 can be minimized when the angle of the rear surface of the front overlapping portion 510a with respect to the X direction is set to 10° or more and 40° or less. The same applies to the angle of the rear window 520 with respect to the X direction. In the first example, the angle of the windshield 510 with respect to the X direction is about 31°. In the first example, the angle of the rear window 520 with respect to the X direction is about 23.5°. However, the angles of the windshield 510 and the rear window 520 with respect to the X direction may be freely set if a desired antenna gain can be obtained in any range of the elevation angle and the azimuth angle.
  • The spacing between the front antenna 10A and the windshield 510 also contributes to the radiation of radio waves from the front antenna 10A. For this reason, the front antenna 10A and the windshield 510 are desirably spaced apart by a predetermined spacing. The same applies to the rear antenna 10B and the rear window 520.
  • FIG. 13 is a view of the front antenna 10A and the windshield 510 as viewed from the left direction of the vehicle 50. In FIG. 13, the front antenna 10A is illustrated as the antenna case having a generally rectangular parallelepiped shape that accommodates the antenna element.
  • As shown in FIG. 13, in the first example, the spacing Gx in the X direction between the front surface of the front antenna 10A and the portion of the rear surface of the windshield 510 closest to the front surface of the front antenna 10A in the X direction is 20 mm, and the spacing Gz in the Z direction between the upper surface of the front antenna 10A and the portion of the rear surface of the windshield 510 closest to the upper surface of the front antenna 10A in the Z direction is 11.8 mm. In the first example, the spacing in the X direction between the rear surface of the rear antenna 10B and the portion of the front surface of the rear window 520 closest to the rear surface of the rear antenna 10B in the X direction is 20 mm, and the spacing in the Z direction between the upper surface of the rear antenna 10B and the portion of the front surface of the rear window 520 closest to the upper surface of the rear antenna 10B in the Z direction is 8.5 mm.
  • The characteristics of the front antenna 10A, such as radiation characteristics and impedance, may change as the front antenna 10A and the windshield 510 are close to each other. Therefore, the spacing Gx shown in FIG. 13 is desirably 1/4 times or more the wavelength of the operation frequency of the front antenna 10A, for example. When the front antenna 10A and the windshield 510 are too far apart from each other, on the other hand, radio waves radiated from the front antenna 10A may be reflected by the windshield 510. Therefore, the spacing Gx shown in FIG. 13 is desirably 1/2 or less of the wavelength of the operation frequency of the front antenna 10A, for example. The spacing Gz shown in FIG. 13 is desirably 1/10 times or more of the wavelength of the operation frequency of the front antenna 10A, for example. The same applies to the spacing between the rear antenna 10B and the rear window 520.
  • The spacing between the front antenna 10A and the windshield 510 and the spacing between the rear antenna 10B and the rear window 520 are not limited to the examples described above. The spacings may be freely set if a desired antenna gain can be achieved in any range of the elevation angle and the azimuthal angle.
  • Next, a variant of the radio wave transmissive body will be described.
  • The antennas such as the front antenna 10A and the rear antenna 10B may overlap with a radio wave transmissive body different from the glass such as the windshield 510 and the rear window 520. Examples of the radio wave transmissive body include resin bodies such as a resin panel, a resin cover, a resin component, and the like. The resin body is radio wave transmissive. The resin body may or may not be light transmissive. The resin body is disposed inside the vehicle, for example. The resin body is provided for the purpose of fixing an antenna or surrounding components of the antenna, improving appearance and design, improving dustproof, waterproof, or durability, and the like.
  • In one example, the resin body such as a resin panel may be present on the radiation direction side of the antenna. In this example, the resin body may be disposed between the antenna and the glass, for example.
  • In another example, a resin body such as a resin cover may cover at least a portion of the antenna. In the other examples, the resin body may cover the antenna with the resin body open on the side on which the glass is positioned with respect to the antenna, for example. When the resin body covers the antenna with the resin body open on the side on which the glass is positioned with respect to the antenna, the antenna may be disposed in the space enclosed by the resin body and the glass. Alternatively, in the other examples, the resin body may cover the antenna including a side on which the glass is positioned with respect to the antenna. When the resin body covers the antenna including the side on which the glass is positioned with respect to the antenna, the antenna may be disposed in the space enclosed by the resin body.
  • In still another example, a resin body such as a resin component may be provided as a bracket that fixes the antenna to the vehicle.
  • An example in which the resin body is inclined obliquely upward with respect to the front-rear direction from the front side toward the rear side will be described. The antenna radiates radio waves from the rear side toward the resin body. Hereinafter, a portion of the resin body overlapping with the projected image of the antenna in the front-rear direction is referred to as an overlapping portion of the resin body. The overlapping portion of the resin body is displaced to a side on which the lower end portion of the resin body is positioned with respect to the central portion between the upper end portion and the lower end portion of the resin body in the same way as the front overlapping portion 510a of the embodiment. Therefore, as in the embodiment, the scattering of radio waves radiated from the antenna on the resin body can be reduced and the directivity gain can be improved as compared with the case where the overlapping portion of the resin body is positioned on the central portion of the resin body or is displaced to the side on which the upper end portion of the resin body is positioned with respect to the central portion of the resin body. A conductor such as a sheet metal may be provided on the lower front side of the antenna as in the embodiment. As in the embodiment, the conductor is disposed in front of the lower end portion of the resin body. As in the embodiment, the directivity gain can be improved when the conductor is provided as compared with when the conductor is not provided.
  • Although the embodiments and variants of the present invention have been described above with reference to the accompanying drawings, these are merely examples of the present invention, and various other configurations may be employed.
  • According to the present specification, the following aspects of an antenna device and a method of mounting an antenna device are provided.
    • (Aspect 1)
  • In Aspect 1, an antenna device includes an antenna to radiate radio waves toward a radio wave transmissive body, the radio wave transmissive body including both end portions opposite to each other, the radio wave transmissive body being inclined at a predetermined angle with respect to a predetermined direction between the both end portions from one side to the other side in the predetermined direction, the radio waves being radiated from the other side, in which a portion of the radio wave transmissive body that overlaps a projected image of the antenna in the predetermined direction is displaced to a side on which an end portion of the both end portions on the one side of the radio wave transmissive body is positioned with respect to a central portion between the both end portions of the radio wave transmissive body.
  • The "predetermined direction" corresponds to the "X direction" of the embodiment and variant described above. The "radio wave transmissive body" corresponds to the "windshield" and the "rear window" of the embodiment and variant described above. The "antenna" corresponds to the "front antenna" and the "rear antenna" of the embodiment and variant described above.
  • According to the aspect described above, the scattering of radio waves radiated from the antenna on the radio wave transmissive body can be reduced as compared to the case where the portion of the radio wave transmissive body overlapping the image of the antenna is positioned at the central portion of the radio wave transmissive body or is displaced to a side where the other end portion of the radio wave transmissive body is positioned with respect to the central portion of the radio wave transmissive body. Therefore, the directivity can be ensured over a wide range with a small number of antennas as compared with the case where the portion of the radio wave transmissive body that overlaps the image of the antenna is positioned at the central portion of the radio wave transmissive body or is displaced to a side where the other end portion of the radio wave transmissive body is positioned with respect to the central portion of the radio wave transmissive body.
    • (Aspect 2)
  • In Aspect 2, a plurality of the antennas is positioned on opposite sides in the predetermined direction.
  • According to the aspect described above, the directivity can be ensured over a wide range as compared with the case where a single antenna is used.
    • (Aspect 3)
  • In Aspect 3, the antenna is positioned with a conductor disposed on the one side with respect to the end portion on the one side of the radio wave transmissive body.
  • According to the aspect described above, the radio waves radiated from the antenna can propagate through the conductor. Therefore, the gain of the antenna can be ensured as compared with the case where the conductor is not disposed.
    • (Aspect 4)
  • In Aspect 4, the antenna is positioned with the portion of the radio wave transmissive body that overlaps the image of the antenna and a black ceramic provided at the radio wave transmissive body displaced from each other.
  • According to the aspect described above, the black ceramic can be less likely to inhibit the transmission of the radio wave radiated from the antenna than when the portion of the radio wave transmissive body that overlaps the image of the antenna and the black ceramic overlap each other. Therefore, the gain of the antenna can be improved as compared with the case where the portion of the radio wave transmissive body that overlaps the image of the antenna and the black ceramic overlap each other.
    • (Aspect 5)
  • In Aspect 5, the black ceramic defines a recess portion at least partially surrounding the portion of the radio wave transmissive body that overlaps the image of the antenna.
  • According to the aspect described above, the overlap between the antenna and the black ceramic in the predetermined direction can be avoided by the recess portion. Therefore, the degree of freedom of the mounting position of the antenna can be increased as compared with the case where the recess portion is not provided.
    • (Aspect 6)
  • In Aspect 6, the antenna and the portion of the radio wave transmissive body that overlaps the image of the antenna are spaced apart in the predetermined direction by a spacing of 1/4 times or more and 1/2 times or less of a wavelength of an operation frequency of the antenna.
  • According to the aspect described above, the change in the characteristics of the antenna can be reduced as compared with the case where the spacing in the predetermined direction between the antenna and the portion of the radio wave transmissive body that overlaps the image of the antenna is less than 1/4 of the wavelength of the operation frequency of the antenna. According to the aspect described above, the reflection of radio waves radiated from the antenna on the radio wave transmissive body can be reduced as compared with the case where the spacing in the predetermined direction between the antenna and the portion of the radio wave transmissive body that overlaps the image of the antenna is more than 1/2 of the wavelength of the operation frequency of the antenna.
    • (Aspect 7)
  • In Aspect 7, the radio wave transmissive body is a light transmissive body.
  • According to the aspect described above, the directivity can be ensured over a wide range with a small number of antennas when the antenna is disposed on the light transmissive body.
    • (Aspect 8)
  • In Aspect 8, the antenna is a V2X antenna.
  • According to the aspect described above, the directivity can be ensured over a wide range with a small number of V2X antennas.
    • (Aspect 9)
  • In Aspect 9, a method of mounting an antenna device includes positioning an antenna to radiate radio waves toward a radio wave transmissive body, the radio wave transmissive body including both end portions opposite to each other, the radio wave transmissive body being inclined at a predetermined angle with respect to a predetermined direction between the both end portions from one side to the other side in the predetermined direction, the radio waves being radiated from the other side, in which a portion of the radio wave transmissive body that overlaps a projected image of the antenna in the predetermined direction is displaced to a side on which an end portion of the both end portions on the one side of the radio wave transmissive body is positioned with respect to a central portion between the both end portions of the radio wave transmissive body.
  • According to the aspect described above, the directivity can be ensured over a wide range with a small number of antennas as in Aspect 1.
    • (Aspect 10)
  • In Aspect 10, a plurality of the antennas is positioned on opposite sides in the predetermined direction.
  • According to the aspect described above, the directivity can be ensured over a wide range as compared with the case where a single antenna is used.
    • (Aspect 11)
  • In Aspect 11, the antenna is positioned with a conductor disposed on the one side with respect to the end portion on the one side of the radio wave transmissive body.
  • According to the aspect described above, the gain of the antenna can be ensured, as in Aspect 3, as compared with the case where the conductor is not disposed.
    • (Aspect 12)
  • In Aspect 12, the antenna is positioned with the portion of the radio wave transmissive body that overlaps the image of the antenna and a black ceramic provided at the radio wave transmissive body displaced from each other.
  • According to the aspect described above, the gain of the antenna can be improved, as in Aspect 4, as compared with the case where the portion of the radio wave transmissive body that overlaps the image of the antenna and the black ceramic overlap each other.
    • (Aspect 13)
  • In Aspect 13, the black ceramic defines a recess portion at least partially surrounding the portion of the radio wave transmissive body that overlaps the image of the antenna.
  • According to the aspect described above, the degree of freedom of the mounting position of the antenna can be increased, as in Aspect 5, as compared with the case where the recess portion is not provided.
    • (Aspect 14)
  • In Aspect 14, the antenna and the portion of the radio wave transmissive body that overlaps the image of the antenna are spaced apart in the predetermined direction by a spacing of 1/4 times or more and 1/2 times or less of a wavelength of an operation frequency of the antenna.
  • According to the aspect described above, the change in the characteristics of the antenna and the reflection of the radio wave radiated from the antenna on the radio wave transmissive body can be reduced as in Aspect 6.
    • (Aspect 15)
  • In Aspect 15, the radio wave transmissive body is a light transmissive body.
  • According to the aspect described above, the directivity can be ensured over a wide range with a small number of antennas when the antenna is disposed on the light transmissive body.
    • (Aspect 16)
  • In Aspect 16, the antenna is a V2X antenna.
  • According to the aspect described above, the directivity can be ensured over a wide range with a small number of V2X antennas.
  • This application claims priority based on US Provisional Application No. 63/453773, filed on March 22, 2023 , the entire disclosure of which is incorporated herein by reference.
    • REFERENCE SIGNS LIST
  • 1,1K antenna device, 10A front antenna, 10B rear antenna, 50 vehicle, 110A front antenna case, 120A front cable, 500 body, 500a front conductor, 500b rear conductor, 502 roof, 504 hood, 506 trunk lid, 510 windshield, 510a, 510aK front overlapping portion, 512 black ceramic, 512a recess portion, 520 rear window, 520a, 520aK rear overlapping portion

Claims (16)

  1. An antenna device comprising:
    an antenna to radiate radio waves toward a radio wave transmissive body, the radio wave transmissive body including both end portions opposite to each other, the radio wave transmissive body being inclined at a predetermined angle with respect to a predetermined direction between the both end portions from one side to the other side in the predetermined direction, the radio waves being radiated from the other side,
    wherein a portion of the radio wave transmissive body that overlaps a projected image of the antenna in the predetermined direction is displaced to a side on which an end portion of the both end portions on the one side of the radio wave transmissive body is positioned with respect to a central portion between the both end portions of the radio wave transmissive body.
  2. The antenna device according to Claim 1,
    wherein a plurality of the antennas is positioned on opposite sides in the predetermined direction.
  3. The antenna device according to Claim 1 or 2,
    wherein the antenna is positioned with a conductor disposed on the one side with respect to the end portion on the one side of the radio wave transmissive body.
  4. The antenna device according to Claim 1 or 2,
    wherein the antenna is positioned with the portion of the radio wave transmissive body that overlaps the image of the antenna and a black ceramic provided at the radio wave transmissive body displaced from each other.
  5. The antenna device according to Claim 4,
    wherein the black ceramic defines a recess portion at least partially surrounding the portion of the radio wave transmissive body that overlaps the image of the antenna.
  6. The antenna device according to Claim 1 or 2,
    wherein the antenna and the portion of the radio wave transmissive body that overlaps the image of the antenna are spaced apart in the predetermined direction by a spacing of 1/4 times or more and 1/2 times or less of a wavelength of an operation frequency of the antenna.
  7. The antenna device according to Claim 1 or 2,
    wherein the radio wave transmissive body is a light transmissive body.
  8. The antenna device according to Claim 1 or 2,
    wherein the antenna is a V2X antenna.
  9. A method of mounting an antenna device, comprising:
    positioning an antenna to radiate radio waves toward a radio wave transmissive body, the radio wave transmissive body including both end portions opposite to each other, the radio wave transmissive body being inclined at a predetermined angle with respect to a predetermined direction between the both end portions from one side to the other side in the predetermined direction, the radio waves being radiated from the other side,
    wherein a portion of the radio wave transmissive body that overlaps a projected image of the antenna in the predetermined direction is displaced to a side on which an end portion of the both end portions on the one side of the radio wave transmissive body is positioned with respect to a central portion between the both end portions of the radio wave transmissive body.
  10. The method of mounting an antenna device according to Claim 9,
    wherein a plurality of the antennas is positioned on opposite sides in the predetermined direction.
  11. The method of mounting an antenna device according to Claim 9 or 10,
    wherein the antenna is positioned with a conductor disposed on the one side with respect to the end portion on the one side of the radio wave transmissive body.
  12. The method of mounting an antenna device according to Claim 9 or 10,
    wherein the antenna is positioned with the portion of the radio wave transmissive body that overlaps the image of the antenna and a black ceramic provided at the radio wave transmissive body displaced from each other.
  13. The method of mounting an antenna device according to Claim 12,
    wherein the black ceramic defines a recess portion at least partially surrounding the portion of the radio wave transmissive body that overlaps the image of the antenna.
  14. The method of mounting an antenna device according to Claim 9 or 10,
    wherein the antenna and the portion of the radio wave transmissive body that overlaps the image of the antenna are spaced apart in the predetermined direction by a spacing of 1/4 times or more and 1/2 times or less of a wavelength of an operation frequency of the antenna.
  15. The method of mounting an antenna device according to Claim 9 or 10,
    wherein the radio wave transmissive body is a light transmissive body.
  16. The method of mounting an antenna device according to Claim 9 or 10,
    wherein the antenna is a V2X antenna.
EP23928720.4A 2023-03-22 2023-05-29 Antenna device and installation method for antenna device Pending EP4685997A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US202363453773P 2023-03-22 2023-03-22
PCT/JP2023/019932 WO2024195144A1 (en) 2023-03-22 2023-05-29 Antenna device and installation method for antenna device

Publications (1)

Publication Number Publication Date
EP4685997A1 true EP4685997A1 (en) 2026-01-28

Family

ID=92841676

Family Applications (1)

Application Number Title Priority Date Filing Date
EP23928720.4A Pending EP4685997A1 (en) 2023-03-22 2023-05-29 Antenna device and installation method for antenna device

Country Status (4)

Country Link
EP (1) EP4685997A1 (en)
JP (1) JPWO2024195144A1 (en)
CN (1) CN120826833A (en)
WO (1) WO2024195144A1 (en)

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019073667A1 (en) 2017-10-13 2019-04-18 株式会社ヨコオ Patch antenna and vehicle-mounted antenna device

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5796159B2 (en) * 2011-03-11 2015-10-21 パナソニックＩｐマネジメント株式会社 Vehicle antenna device
JP7643450B2 (en) * 2020-03-24 2025-03-11 Ａｇｃ株式会社 Vehicle Antenna System

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019073667A1 (en) 2017-10-13 2019-04-18 株式会社ヨコオ Patch antenna and vehicle-mounted antenna device

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of WO2024195144A1

Also Published As

Publication number Publication date
WO2024195144A1 (en) 2024-09-26
CN120826833A (en) 2025-10-21
JPWO2024195144A1 (en) 2024-09-26

Similar Documents

Publication Publication Date Title
US11069961B2 (en) Antenna device having an antenna element coupled at a notch of a ground conductor thereof
US6919853B2 (en) Multi-band antenna using an electrically short cavity reflector
US20190280365A1 (en) Vehicle integrated antenna with enhanced beam steering
CN1866614B (en) Vehicle-mounted antenna system
US20110140975A1 (en) Combo antenna apparatus for vehicle
CN110574230B (en) Vehicle-mounted antenna device
CN107978844A (en) Vehicle antenna and the glass pane with antenna
JP2002524952A (en) Mobile communication antenna
EP1769565B1 (en) Multiservice antenna system assembly
EP4685997A1 (en) Antenna device and installation method for antenna device
CN115362598B (en) Vehicle antenna system
WO2022270314A1 (en) Vehicle wireless device
JP2006186880A (en) Circularly polarized antenna
JP7781855B2 (en) Antenna device
US20030162524A1 (en) Motor vehicle outside rear-view mirror
US7482988B2 (en) Noise reception reducing arrangement
JPH10327010A (en) In-vehicle antenna device
JP7424617B2 (en) antenna device
US12586890B2 (en) Antenna device and vehicle including the same
JP4705558B2 (en) ETC built-in inner mirror, antenna arrangement configuration, and antenna arrangement method
EP4568018A1 (en) Antenna assembly, signal transmission apparatus, and vehicle
US12620713B2 (en) Patch antenna and antenna device
US20240322422A1 (en) Antenna device
CN119511210A (en) Radar System
CN121336320A (en) Antenna assembly mounted on a vehicle

Legal Events

Date Code Title Description
STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE INTERNATIONAL PUBLICATION HAS BEEN MADE

PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: REQUEST FOR EXAMINATION WAS MADE

17P Request for examination filed

Effective date: 20250922

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC ME MK MT NL NO PL PT RO RS SE SI SK SM TR