Vehicle antenna system

Abstract

A vehicle antenna system includes: a first antenna installed near the front windshield of the vehicle; and a second antenna installed near the rear windshield of the vehicle. The first antenna and the second antenna are capable of transmitting and receiving radio waves in a specified frequency band F. When viewed from a viewpoint in the normal direction of a horizontal plane, and when areas A and B are given by the vehicle's central axis extending in the direction of vehicle travel and dividing the vehicle's width into two equal parts, the first antenna is configured in area A and the second antenna is configured in area B.

Description

Technical Field

[0001] The present invention relates to an antenna system for a vehicle. Background Art

[0002] In recent years, there has been a trend toward expanding services using high-speed / high-capacity wireless communication systems that utilize frequency bands in the GHz (gigahertz) band, such as the transition from 4G LTE (800MHz band) to 5G (sub6). Specifically, there is a trend toward expanding the frequency band used for such services from the 3GHz band to the 5-6GHz band. Furthermore, efforts are underway to promote the widespread use of wireless communication systems that utilize frequency bands higher than sub6 (e.g., the 28GHz band, the 40GHz band, the 60GHz band, and the 80GHz band).

[0003] As such a wireless communication system, an antenna system including a vehicle antenna capable of transmitting and receiving radio waves in the 5G (sub6) frequency band has been disclosed (for example, see Patent Document 1).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: International Publication No. 2019 / 208453 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] However, there is an increasing demand for achieving higher levels of both improvement in antenna gain and widening of directivity over the entire circumference of the horizontal plane centered on the vehicle.

[0009] Therefore, the present disclosure provides a vehicle antenna system capable of achieving both improvement in antenna gain and widening of directivity in the horizontal plane direction.

[0010] Technical solutions to problems

[0011] The present disclosure provides a vehicle antenna system comprising: a first antenna installed near the front windshield of the vehicle; and a second antenna installed near the rear windshield of the vehicle. The first antenna and the second antenna are capable of transmitting and receiving radio waves in a specified frequency band F. When viewed from a viewpoint in the normal direction of a horizontal plane, and when areas A and B are given by the vehicle's central axis extending in the direction of travel of the vehicle and dividing the vehicle's width into two equal parts, the first antenna is configured in area A and the second antenna is configured in area B.

[0012] Effects of the Invention

[0013] According to the technology disclosed in the present disclosure, it is possible to provide a vehicle antenna system that can achieve both improvement in antenna gain and widening of the directivity angle in the horizontal plane direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a diagram showing an example of a vehicle equipped with a vehicle antenna system, as viewed from above.

[0015] Figure 2 This is a diagram showing an example of the directivity of each antenna when viewed from above the vehicle.

[0016] Figure 3 This is a diagram showing an example of the directivity of each antenna on the vertical plane.

[0017] Figure 4 This is a diagram showing an example of an antenna disposed near the front windshield when viewed from above the vehicle.

[0018] Figure 5 This is a diagram showing an example of an antenna arranged near the front windshield when viewed from the front of the vehicle.

[0019] Figure 6 This is a diagram showing an example of an antenna disposed near the rear windshield when viewed from above the vehicle.

[0020] Figure 7 This is a diagram showing an example of an antenna arranged near the rear windshield when viewed from the rear of the vehicle.

[0021] Figure 8 This is a diagram showing another example of an antenna disposed near the rear windshield when viewed from the rear of the vehicle.

[0022] Figure 9 It is a three-dimensional schematic diagram of the antenna.

[0023] Figure 10 It is a schematic cross-sectional view of the antenna at α-α'.

[0024] Figure 11 FIG. 3 is a schematic cross-sectional view of the antenna at β-β'.

[0025] Figure 12 This is a diagram showing the measurement results of the antenna gain in the horizontal direction in Example 1.

[0026] Figure 13 This is a diagram showing a vehicle equipped with the vehicle antenna system of Comparative Example 1, as viewed from above.

[0027] Figure 14 1 is a diagram showing the measurement results of the antenna gain in the horizontal direction in Comparative Example 1. DETAILED DESCRIPTION

[0028] Hereinafter, the embodiments of the present disclosure will be described with reference to the accompanying drawings. In addition, in each embodiment, in parallel, right angles, orthogonal, horizontal, vertical, up and down, left and right, a degree of deviation that does not impair the effect of the present invention is allowed. In addition, the X-axis direction, the Y-axis direction, and the Z-axis direction respectively represent a direction parallel to the X-axis, a direction parallel to the Y-axis, and a direction parallel to the Z-axis. The X-axis direction, the Y-axis direction, and the Z-axis direction are orthogonal to each other. The XY plane, the YZ plane, and the ZX plane respectively represent an imaginary plane parallel to the X-axis direction and the Y-axis direction, an imaginary plane parallel to the Y-axis direction and the Z-axis direction, and an imaginary plane parallel to the Z-axis direction and the X-axis direction.

[0029] The vehicle antenna system described in this disclosure primarily focuses on systems capable of transmitting and receiving radio waves in the sub-6 (less than 6 GHz) frequency band used in fifth-generation mobile communication systems (5G), but is not limited to sub-6. The vehicle antenna system described in this disclosure may also be capable of transmitting and receiving radio waves in the 3 GHz to 30 GHz SHF (Super High Frequency) band used in 5G, as well as the 30 GHz to 300 GHz EHF (Extremely High Frequency) band, known as millimeter waves.

[0030] Figure 1 This figure shows an example of a vehicle equipped with a vehicle antenna system according to an embodiment of the present disclosure, viewed from above. Viewing from above corresponds to viewing from a viewpoint normal to a horizontal plane (ground). Figure 1 The illustrated vehicle antenna system 101 is an example of a vehicle antenna system including a plurality of antenna groups provided on or near dielectric materials located on both the front and rear sides of the vehicle 100. Examples of the dielectric material include glass and resin.

[0031] In each of the drawings, the X-axis direction corresponds to the width direction of the vehicle 100, the Y-axis direction corresponds to the front-rear direction (travel direction) of the vehicle 100, and the Z-axis direction corresponds to the up-down direction of the vehicle 100. Furthermore, the XY plane corresponds to the horizontal plane, and the Z-axis direction corresponds to the normal direction (vertical direction) of the horizontal plane.

[0032] Figure 1 This schematic diagram shows a vehicle antenna system 101, illustrating an example of a configuration of multiple antennas installed near the front and rear window panes of a vehicle 100. A first antenna 1 is installed near a front windshield 110, which is a dielectric material located on the front side of the vehicle 100, and a second antenna 2 is installed near a rear windshield 120, which is a dielectric material located on the rear side of the vehicle 100.

[0033] In addition, Figure 1In the XY plane, an imaginary line passing through the center of the vehicle 100 in the vehicle width direction, which is the X-axis direction, and parallel to the Y-axis direction is defined as the vehicle center axis 50. Furthermore, the vehicle 100 is divided into two areas, area A and area B, with the vehicle center axis 50 as the boundary line. More specifically, the first antenna 1 is arranged near the inside of the vehicle cabin of the front windshield 110 in area A. In addition, specifically, the so-called "first antenna 1 is arranged in area A" means that the conductor (conductor surface) for transmitting and receiving radio waves by the antenna 1 is arranged in area A, for example, excluding the shell supporting the conductor. In other words, in this case, a part of the shell that only supports the first antenna 1 and does not contribute to the transmission and reception of radio waves may also be arranged in area B.

[0034] Furthermore, the second antenna 2 is located in area B. More specifically, the second antenna 2 is located near the interior of the vehicle cabin relative to the rear windshield 120 or near the exterior of the vehicle cabin relative to the rear windshield 120. Here, "near the exterior of the vehicle cabin" includes, for example, a configuration where the second antenna 2 is mounted within an aerodynamic package (exterior component) such as a rear spoiler located at approximately the same height as the roof and mounted on the exterior of the vehicle relative to the rear windshield 120. Furthermore, similarly to the first antenna 1, the phrase "the second antenna 2 is located in area B" suffices as long as the conductor (conductor surface) of the second antenna 2 for transmitting and receiving radio waves is located in area B. For example, a portion of a housing that merely supports the conductor and does not contribute to the transmission and reception of radio waves may also be located in area A.

[0035] For example, the first antenna 1 and the second antenna 2 are configured to be capable of transmitting and receiving radio waves in a predetermined frequency band within a range of 3 GHz to 100 GHz. Furthermore, the first antenna 1 and the second antenna 2 are capable of transmitting and receiving radio waves in a predetermined frequency band F within the aforementioned range. For example, when frequency band F includes 5.9 GHz, the predetermined frequency band may be a range of 5.850 GHz to 5.925 GHz. In this case, the vehicle antenna system 101 can be applied to V2X (Vehicle to Everything) and C-V2X (Cellular Vehicle to Everything) for inter-vehicle communications.

[0036] Furthermore, if the first antenna 1 is the only antenna for transmitting and receiving radio waves in the predetermined frequency band F near the front windshield 110 and the second antenna 2 is the only antenna for transmitting and receiving radio waves in the predetermined frequency band F near the rear windshield 120 , the vehicle antenna system 101 is simplified, which is preferable.

[0037] Figure 2This is a schematic diagram showing a vehicle antenna system 101 in which the main beams 11 and 21 of the first antenna 1 and the second antenna 2 have different directions when the vehicle 100 is viewed from the normal of the horizontal plane. The main beams 11 and 21 are beams in directions that can most strongly transmit and receive radio waves in a predetermined frequency band. In addition, the directions of the main beams 11 and 21 are the vector directions of both when radio waves are transmitted from the first antenna 1 and the second antenna 2, or the vector directions of both when radio waves are received from the first antenna 1 and the second antenna 2. Figure 2 In FIG, 10 and 20 respectively represent the range of half-value angles of the main beams 11 and 21 formed by the first antenna 1 and the second antenna 2 when the vehicle 100 is viewed from the normal direction of the horizontal plane. In other words, Figure 2 , the directions of the main beams 11 and 21 formed by the first antenna 1 and the second antenna 2 when the vehicle 100 is viewed from the normal direction of the horizontal plane correspond to the approximate center angles of the half-value angle ranges 10 and 20 centered on the respective main beams.

[0038] Thus, when the vehicle 100 is viewed from the normal direction of the horizontal plane, by setting the direction of the main beam 11 of the first antenna 1 and the direction of the main beam 21 of the second antenna 2 to be different, the reception sensitivity of radio waves arriving from all directions around the vehicle 100 can be improved.

[0039] The angle formed by the direction of the main beam 11 of the first antenna 1 and the direction of the main beam 21 of the second antenna 2 when the vehicle 100 is viewed from the normal direction of the horizontal plane is referred to as θ. 12 At this time, the angle θ 12 It only needs to be 120° or more and 240° or less, preferably 135° or more and 225° or less, more preferably 150° or more and 210° or less, and even more preferably 165° or more and 195° or less. 12 By setting the range to this level, the reception sensitivity of the vehicle antenna system 101 to radio waves arriving from all directions in all directions can be further improved.

[0040] Figure 3 Schematic diagram showing the ranges 10 and 20 of the half-value angles of the first antenna 1 and the second antenna 2, respectively, centered around the main beams 11 and 21, when the vehicle 100 is viewed from the side (YZ plane). Figure 3In this example, the angle (elevation angle) of main beam 11 relative to horizontal plane 90 is α, and the angle (elevation angle) of main beam 21 relative to the horizontal plane is β. In this case, for example, by setting elevation angles α and β within the range of -20° to 60°, the reception sensitivity of radio waves arriving from above and below vehicle 100 can be improved. Furthermore, elevation angles α and β are preferably within the range of -10° to 40°, and more preferably within the range of -5° to 20°.

[0041] Next, the detailed configuration of the first antenna 1 will be described. Figure 4 1 is an enlarged schematic diagram showing a portion of the vehicle 100 including the front windshield 110 when the vehicle 100 is viewed from the normal direction of the horizontal plane. First, if the distance in the vehicle width direction passing through the front windshield 110 of the first antenna 1 is denoted as W F , then the distance in the vehicle width direction in area A is W F Furthermore, in region A, when the region is divided into a front first region 111 located on the side of the end edge (metal frame, such as the A-pillar) of the front windshield 110 and a front second region 112 located on the side of the vehicle's central axis 50 by a front boundary line 60 that is substantially perpendicular to the vehicle width direction of the front windshield 110, the first antenna 1 is disposed in the front first region 111.

[0042] In other words, the front boundary line 60 is an imaginary line extending in a direction substantially perpendicular to the vehicle width direction, passing through the end of the first antenna 1 opposite to the edge of the front windshield 110. Furthermore, the front boundary line 60 divides the front windshield 110, which is arranged in area A, into a front first area 111 and a front second area 112. Here, the distance in the vehicle width direction passing through the first antenna 1 in the front first area 111 is denoted as W. F1 , will be located at the W F1 The distance in the vehicle width direction in the front second area 112 on the extension line of F2 At this time, with W F1 / (W F1 +W F2 ) is greater than 0.05 and less than 0.90, the first antenna 1 can be configured. F / 2=W F1 +W F2 relationship.

[0043] Here, if W F1 / (W F1 +W F2 ) exceeds 0.90, the reception sensitivity of the first antenna 1 on the vehicle width direction side of the vehicle 100 may be reduced. F1 / (W F1 +W F2) exceeds 0.90, the first antenna 1 may be physically impossible to place near a rearview mirror and close to a housing housing a camera, rain sensor, etc., or may interfere with the camera, etc., generating unnecessary noise. F1 / (W F1 +W F2 ) is less than 0.05, the first antenna 1 may be close to the metal frame (A-pillar) of the vehicle body 100, thereby reducing the antenna gain. F1 / (W F1 +W F2 ) is preferably 0.10 or more and 0.80 or less, more preferably 0.10 or more and 0.70 or less.

[0044] Figure 5 1 is a schematic diagram (XZ plane) when the vehicle 100 is viewed from the front, that is, from the Y-axis direction. Figure 5 The vehicle center axis 50 is omitted in FIG. 1 , but with respect to a line (in the Z-axis direction) along the center of the vehicle width direction of the vehicle 100, the left side is region A and the right side is region B. Figure 5 The highest position V of the roof when viewed from the front of the vehicle 100 is R To the lowest position F of the front windshield 110 B The distance in the normal direction of the horizontal plane, that is, the vertical direction (Z-axis direction) is set as H F At this time, although it depends on the specifications of the vehicle 100, the first antenna 1 is arranged at a distance of V R 0.5×H F When the first antenna 1 is configured at a distance from position V R More than 0.5×H F If the first antenna 1 is located at a position V, the field of view of the occupants of the vehicle 100 may be unnecessarily blocked, and the antenna gain may be reduced due to the influence of the ground, the vehicle hood, etc. R 0.4×H F More preferably, it is arranged within a distance of V R 0.3×H F Within.

[0045] In addition, Figure 5 The highest position F of the front windshield 110 when viewed from the front of the vehicle 100 is T To the lowest position F of the front windshield 110 B The distance in the normal direction of the horizontal plane, that is, the vertical direction (Z-axis direction) is set as H GF At this time, although it depends on the specifications of the vehicle 100, the first antenna 1 is arranged at a distance from the position F T 0.5×H GFWhen the first antenna 1 is configured at a distance from position F T More than 0.5×H GF If the position F is too low, the view of the occupants of the vehicle 100 may be blocked unnecessarily, and the antenna gain may be reduced due to the influence of the ground, the vehicle hood, etc. In addition, the first antenna 1 is preferably arranged at a distance from the position F. T 0.4×H GF More preferably, it is arranged within a distance of F T 0.3×H GF In addition, the first antenna 1 can also be located at position F T The heights are arranged adjacent to each other.

[0046] Next, the detailed configuration of the second antenna 2 will be described. Figure 6 1 is an enlarged schematic diagram showing a portion of the vehicle 100 including the rear windshield 120 when the vehicle 100 is viewed from the normal direction of the horizontal plane. First, if the distance in the vehicle width direction of the rear windshield 120 passing through the second antenna 2 is denoted as W R , then the distance in the vehicle width direction in area B is W R Furthermore, in region B, when the region is divided into a first rear region 121 located on the side of the end edge (metal frame (e.g., C-pillar)) of the rear windshield 120 and a second rear region 122 located on the side of the vehicle center axis 50, passing through a rear boundary line 70 that is substantially perpendicular to the vehicle width direction of the rear windshield 120, the second antenna 2 is arranged in the first rear region 121.

[0047] In other words, the rear boundary line 70 extends in a direction substantially perpendicular to the vehicle width direction through the end portion of the second antenna 2 opposite to the end edge of the rear windshield 120. Furthermore, the rear boundary line 70 divides the rear windshield 120 disposed in region B into a first rear region 121 and a second rear region 122. Here, the distance in the vehicle width direction passing through the second antenna 2 in the first rear region 121 is denoted as W. R1 , will be located at the W R1 The distance in the vehicle width direction in the rear second region 122 on the extension line of R2 At this time, with W R1 / (W R1 +W R2 ) is less than 0.90 and the second antenna 2 can be configured. R / 2=W R1 +W R2 relationship.

[0048] If W R1 / (W R1 +W R2) exceeds 0.90, the receiving sensitivity of the second antenna 2 on the vehicle width direction side of the vehicle 100 may be reduced. R1 / (W R1 +W R2 ) exceeds 0.90, there is a possibility that the second antenna 2 will obstruct the rear view, or it may be physically impossible to place it close to vehicle lamps such as high-mounted brake lights, or in the case of a vehicle equipped with a rear camera, it may interfere with the camera and generate unnecessary noise. R1 / (W R1 +W R2 ) is preferably 0.80 or less, more preferably 0.70 or less.

[0049] In addition, when the second antenna 2 is installed near the vehicle interior side of the rear windshield 120, W R1 / (W R1 +W R2 ) is preferably 0.05 or more, more preferably 0.10 or more. In this case, if W R1 / (W R1 +W R2 ) is less than 0.05, the second antenna 2 may be close to the metal frame of the vehicle 100 (e.g., C-pillar), thereby reducing the antenna gain. In addition, when the second antenna is mounted in an aerodynamic kit such as the aforementioned rear spoiler, it can be placed in a portion that protrudes toward the rear of the vehicle 100 from the metal frame. R1 / (W R1 +W R2 ) is not limited to 0.05 or more and 0.90 or less, and the lower limit may be less than 0.05 or 0.03 or less. In this case, as W R1 / (W R1 +W R2 ) is less than 0.05, and may be in the range of 0.01 to 0.04.

[0050] Figure 7 1 is a schematic diagram (XZ plane) when the vehicle 100 is viewed from the rear, that is, from the Y-axis direction. Figure 7 The vehicle center axis 50 is omitted in FIG. 1 , but with respect to a line (in the Z-axis direction) along the center of the vehicle width direction of the vehicle 100, the right side is region A and the left side is region B. Figure 7 The highest position V of the roof when viewed from the rear of the vehicle 100 is R To the lowest position R of the rear windshield 120 B The distance in the normal direction of the horizontal plane, that is, the vertical direction (Z-axis direction) is set as H R At this time, although it depends on the specifications of the vehicle 100, the second antenna 2 is arranged at a distance from the position V R0.5×H R When the second antenna 2 is placed at a distance from position V R More than 0.5×H R If the second antenna 2 is located at a position V, the field of view of the vehicle 100 may be unnecessarily blocked, and the antenna gain may be reduced due to the influence of the ground, the vehicle body, etc. R 0.4×H R More preferably, it is arranged within a distance of V R 0.3×H R Within.

[0051] In addition, Figure 7 The highest position R of the rear windshield 120 when viewed from the rear of the vehicle 100 is T To the lowest position R of the rear windshield 120 B The distance in the normal direction of the horizontal plane, that is, the vertical direction (Z-axis direction) is set as H GR At this time, although it depends on the specifications of the vehicle 100, the second antenna 2 is arranged at a distance from the position R T 0.5×H GR When the second antenna 2 is configured at a distance from position R T More than 0.5×H GR When the second antenna 2 is positioned at a distance from the position R, the field of view of the occupants of the vehicle 100 may be unnecessarily blocked, and the antenna gain may be reduced due to the influence of the ground, the vehicle body, etc. T 0.3×H GR More preferably, it is arranged within the distance R T 0.1×H GR Within.

[0052] in addition, Figure 7 The vehicle 100 shown in FIG. 1 is provided with an example of a rear spoiler 130 protruding toward the rear of the vehicle 100 (in the negative Y-axis direction) along the inclination direction of the roof above the rear windshield 120. In addition, the rear spoiler 130 may also include a vehicle lamp 131 such as a high-mounted stop lamp at the center portion in the vehicle width direction. Figure 7 When looking from behind, if the rear windshield 120 has a portion hidden by the rear spoiler 130 and a portion exposed to the outside of the vehicle, the position R of the rear windshield 120 T The highest position of the rear windshield 120 exposed to the outside of the vehicle. Figure 7 The vehicle 100 is at a position R where the rear windshield 120 is exposed to the outside of the vehicle. T An example of a rear spoiler 130 hidden from rear view.

[0053] At this time, although it depends on the specifications of the vehicle 100, the second antenna 2 is arranged at a distance from the position R T 0.5×H GR If the second antenna 2 is configured at a distance from position R T More than 0.5×H GR The second antenna 2 is preferably arranged at a distance from the position R . T 0.3×H GR More preferably, it is arranged within the distance R T 0.1×H GR Within.

[0054] Figure 8 is a schematic diagram (XZ plane) when the vehicle 100 is viewed from the rear, that is, from the Y-axis direction, and Figure 7 The vehicle 100 shown in FIG. 1 is identical except that it does not have a rear spoiler 130 as an example of an aerodynamic kit. In this case, although it also depends on the specifications of the vehicle 100, the second antenna 2 is arranged at a distance from the position V. R 0.5×H R It can be within, preferably configured at a distance from position V R 0.3×H R More preferably, it is arranged within a distance of V R 0.1×H R Within.

[0055] In addition, Figure 8 The highest position R of the rear windshield 120 when viewed from the rear of the vehicle 100 is T To the lowest position R of the rear windshield 120 B The distance in the normal direction of the horizontal plane, that is, the vertical direction (Z-axis direction) is set as H GR At this time, although it depends on the specifications of the vehicle 100, the second antenna 2 is arranged at a distance from the position R T 0.5×H GR When the second antenna 2 is configured at a distance from position R T More than 0.5×H GR If the antenna is located at a position R, the field of view of the occupants of the vehicle 100 may be blocked unnecessarily, and the antenna gain may be reduced due to the influence of the ground, the vehicle body, etc. T 0.3×H GR More preferably, it is arranged within the distance R T 0.1×H GR Within.

[0056] Next, the first antenna 1 and the second antenna 2 are described. As long as they can transmit and receive the specified frequency F, the first antenna 1 and the second antenna 2 can have the same or different shapes. Furthermore, the first antenna 1 and the second antenna 2 can be configured to transmit and receive waves with a specified polarization. For example, the first antenna 1 and the second antenna 2 can be configured to primarily transmit and receive vertically polarized waves, or to primarily transmit and receive horizontally polarized waves, or to transmit and receive both vertically and horizontally polarized waves with high sensitivity. Figure 9 is a perspective schematic diagram showing an example of the first antenna 1, Figure 10 yes Figure 9 A schematic cross-sectional view of the first antenna 1 at α-α' (single-dot chain line), Figure 11 yes Figure 9 Schematic cross-sectional view of the first antenna 1 at β-β' (double-dotted chain line). Figures 9 to 11 The first antenna 1 shown is a so-called patch antenna, but the first antenna 1 is not limited thereto. Figure 9 α-α′ and β-β′ are imaginary lines passing through the center of gravity 22 of the radiation plate 16 and being orthogonal to each other.

[0057] exist Figures 9 to 11 In the embodiment, the first antenna 1 includes a radiation plate 16 , a first passive conductor plate 17 , and a second passive conductor plate 18 on a first surface 14 of a dielectric substrate 13 , and includes a conductor plate 12 on a second surface 15 of the dielectric substrate 13 .

[0058] Radiating plate 16 is a plate- or film-shaped conductor arranged opposite conductive plate 12 in the Y-axis direction. Its area is narrower than that of conductive plate 12. Radiating plate 16 is a planar layer whose surface is parallel to the XZ plane and functions as a radiating element of first antenna 1. Examples of the conductor material used for radiating plate 16 include, but are not limited to, silver and copper. While radiating plate 16 is square in shape, it may also be a polygonal shape other than a square, or may have other shapes such as a circle.

[0059] The radiation plate 16 is disposed separately from the conductor plate 12. The medium between the conductor plate 12 and the radiation plate 16 includes at least one of space and a dielectric substrate. Figure 9 、 Figure 10 The dielectric material shown here consists solely of a dielectric substrate 13. Dielectric substrate 13 is a plate-shaped or film-shaped dielectric layer primarily composed of dielectric material. Dielectric substrate 13 has a first surface 14 and a second surface 15 opposite first surface 14. First and second surfaces 14, 15 are parallel to the XZ plane. A radiating plate 16 is provided on first surface 14 of dielectric substrate 13, and a conductive plate 12 is provided on second surface 15.

[0060] The dielectric substrate 13 may be, for example, a dielectric substrate such as a glass epoxy substrate, or a dielectric sheet. Examples of dielectric materials used for the dielectric substrate 13 include, but are not limited to, glass such as quartz glass, ceramics, fluorine-based resins such as polytetrafluoroethylene, liquid crystal polymers, and cycloolefin polymers.

[0061] exist Figure 10 In the illustrated first antenna 1, the power supply unit 25 is a portion that supplies power via contact or non-contact. It is connected to or in close proximity to one end of a power supply line (not shown). Specific examples of the power supply line include a coaxial cable and a microstrip line. The other end of the power supply line is connected to a communication device that uses the first antenna 1 to communicate with the outside of the vehicle. The power supply unit 25 is located on the side of the radiating plate 16 where the conductive plate 12 is located.

[0062] The connection conductor 24 does not contact the conductive plate 12. One end of the connection conductor 24 is connected to the power supply 25, and the other end is connected to the radiating plate 16 at a connection point 23. The connection point 23 is offset from the center of gravity 22 of the radiating plate 16 and, in the illustrated embodiment, is located on the negative side of the center of gravity 22 in the Z-axis direction. If the radiating plate 16 has a symmetrical shape such as a square, the center of gravity 22 corresponds to the center of the symmetrical shape.

[0063] Specific examples of the connecting conductor 24 include a conductor formed inside a through-hole that penetrates the dielectric substrate 13 in the Y-axis direction, a core wire of a coaxial cable, a pin-shaped conductor pin, etc., but the connecting conductor 24 is not limited to these. Furthermore, when the dielectric between the conductor plate 12 and the radiating plate 16 includes a space, specific examples of the connecting conductor 24 include a core wire of a coaxial cable, a conductor pin, etc., but the connecting conductor 24 is not limited to these.

[0064] like Figure 10 As shown, when viewed from the radiating plate 16 side relative to the conductor plate 12, the center of gravity 22 of the radiating plate 16 overlaps with the center of gravity 26 of the conductor plate 12. This is preferable for increasing the antenna gain of the first antenna 1 in the direction from the conductor plate 12 side toward the radiating plate 16 side. In this example, the viewpoint from the radiating plate 16 side relative to the conductor plate 12 refers to the viewpoint from the positive side in the Y-axis direction, and the direction from the conductor plate 12 side toward the radiating plate 16 side refers to the direction toward the positive side in the Y-axis direction.

[0065] exist Figure 9 、 Figure 11In the embodiment, the first passive conductor plate 17 and the second passive conductor plate 18 are conductors arranged separately from each other on either side of the radiating plate 16 in the vehicle width direction (X-axis direction). This arrangement of the first passive conductor plate 17 and the second passive conductor plate 18 improves the antenna gain of the first antenna 1 in the vehicle width direction. Furthermore, the first antenna 1 may or may not include the first passive conductor plate 17 and the second passive conductor plate 18. When the first antenna 1 includes the first passive conductor plate 17 and the second passive conductor plate 18, the antenna gain in the X-axis direction is relatively greater than when the first antenna 1 does not include the first passive conductor plate 17 and the second passive conductor plate 18.

[0066] At least one of the first passive conductive plate 17 and the second passive conductive plate 18 is, for example, a planar layer whose surface is parallel to the XZ plane, and functions as a waveguide element or a reflective element of the first antenna 1. In this example, the first passive conductive plate 17 and the second passive conductive plate 18 are arranged on the same layer and are located away from the center of gravity 22 of the radiating plate 16 when viewed from the side of the radiating plate 16 relative to the conductive plate 12.

[0067] In this example, first passive conductive plate 17 and second passive conductive plate 18 each have a smaller area than conductive plate 12 and radiating plate 16, but the area is not limited thereto. For example, at least one of first passive conductive plate 17 and second passive conductive plate 18 may have a larger area than radiating plate 16.

[0068] Examples of the conductor material used for the first passive conductor plate 17 and the second passive conductor plate 18 include, but are not limited to, silver and copper. Furthermore, while the illustrated first and second passive conductor plates 17 and 18 are rectangular, they may be polygonal shapes other than rectangles, or may be circular or other shapes.

[0069] When viewed from the radiating plate 16 side relative to the conductive plate 12, it is preferable for the first passive conductive plate 17 and the second passive conductive plate 18 to have a line-symmetric shape with respect to the axis of symmetry of the connection point 23 with the radiating plate 16 via the connecting conductor 24, in order to improve the antenna gain of the first antenna 1. In this example, the antenna gain of the first antenna 1 in the X-axis direction is improved.

[0070] In addition, the second antenna 2 may have the same shape as the first antenna 1 as described above, or may have a different shape. In the case where the second antenna 2 has the same shape as the first antenna 1, the second antenna 2 becomes Figures 9 to 11 The first antenna 1 shown has the Y-axis direction inverted in positive and negative directions. That is, the second antenna 2 has the same structure as the first antenna 1 except that the direction from the conductive plate 12 toward the radiating plate 16 is the negative Y-axis direction.

[0071] Here, if Figure 1 The vehicle antenna system 101 shown includes the first antenna 1 and the second antenna 2. As described above, the first antenna 1 is disposed near the front windshield 110 and the second antenna 2 is disposed near the rear windshield 120. Figures 9 to 11 In the case of the patch antenna shown, the surface of the radiation plate 16 can be arranged parallel to the XZ plane, but the arrangement is not limited to this.

[0072] exist Figure 1 In the embodiment, the surface of the radiation plate 16 of the first antenna 1 may be tilted relative to the XZ plane. For example, the surface of the radiation plate 16 of the first antenna 1 may be tilted in the direction perpendicular to the horizontal plane, that is, in the X-axis direction (vehicle width direction). In this case, the angle (γ) of the normal direction of the surface of the radiation plate 16 of the first antenna 1 with the Y-axis direction as the reference when viewed from the Z-axis direction may be set to y1 ) is tilted within the range of -15° to +15°. This configuration is applicable as long as the second antenna 2 has the same shape as the first antenna 1.

[0073] In addition, Figure 1 In the embodiment, the surface of the radiation plate 16 of the first antenna 1 may be arranged to be tilted relative to the XY plane. In this case, the angle (γ) of the normal direction of the surface of the radiation plate 16 of the first antenna 1 with respect to the Y-axis direction when viewed from the side direction (X-axis direction) of the vehicle 100 may be set to y2 ) is tilted within the range of -15° to +15°. This configuration is applicable as long as the second antenna 2 has the same shape as the first antenna 1.

[0074] Thus, the vehicle antenna system 101 according to this embodiment can be configured at the angle γ as described above, as long as the first antenna 1 is disposed in the area A near the front windshield 110 and the second antenna 2 is disposed in the area B near the rear windshield 120. y1 , γ y2 The normal direction of the surface of the radiating plate 16 of each antenna (first antenna 1 and second antenna 2) is appropriately adjusted within a range. Furthermore, the first antenna 1 and second antenna 2 can be mounted on the glass panels on the interior side of the front windshield 110 and rear windshield 120, respectively, via a predetermined housing, or can be mounted on the interior ceiling via a predetermined housing.

[0075] Moreover, the vehicle antenna system 101 involved in this embodiment can also arrange an antenna capable of transmitting and receiving a frequency band different from the frequency band F separately from the first antenna 1 and the second antenna 2 near at least one of the front windshield 110, the rear windshield 120 and the side glass (fixed window glass).

[0076] <Example 1>

[0077] Example 1 Preparation Figure 9 The first antenna 1 shown realizes a vehicle antenna system 101 in which the first antenna 1 and the second antenna 2 of the same shape are mounted on a vehicle 100. Specifically, the first antenna 1 has the following dimensions (unit: mm). Furthermore, a fluororesin substrate is used as the material for the dielectric substrate 13, and copper is used as the material for the radiating plate 16, the first passive conductive plate 17, the second passive conductive plate 18, and the conductive plate 12.

[0078] L12: 22;

[0079] L13:18;

[0080] L14:16;

[0081] L15: 2;

[0082] L16:24;

[0083] L17:29.

[0084] The first antenna 1 is placed in area A near the front windshield 110, and the second antenna 2 is placed in area B near the rear windshield. At this time, the surface of the radiation plate 16 of the first antenna 1 and the second antenna 2 is installed in a manner parallel to the XZ plane (vehicle width direction). Furthermore, the first antenna 1 is placed in the front first area 111, specifically, as the installation position in the vehicle width direction, W F1 / (W F1 +W F2 ) is set to 0.6. In addition, as the installation position in the vertical direction, the first antenna 1 is set to the highest position V from the roof. R 0.2×H F , the highest position F 110 from the front windshield T 0.05×H GF At this time, the angle α of the main beam 11 of the first antenna 1 relative to the horizontal plane is approximately 0°.

[0085] The second antenna 2 is disposed in the rear first area 121. Specifically, as the mounting position in the vehicle width direction, W R1 / (W R1 +W R2 ) is set to 0.2. In addition, as the installation position in the vertical direction, the second antenna 2 is set to the highest position V from the roof. R 0.2×H R , the highest position R of 120 from the rear windshield T 0.05×H GRAt this time, the angle β of the main beam 21 of the second antenna 2 relative to the horizontal plane is approximately 0°. In addition, the angle θ between the direction of the main beam 11 of the first antenna 1 and the direction of the main beam 21 of the second antenna 2 when viewed from the normal direction of the horizontal plane (Z-axis direction) is 12 Set to approximately 180°.

[0086] In the vehicle antenna system 101 of Example 1, the antenna characteristics of the vertically polarized wave at 5.9 GHz included in the predetermined frequency band F were measured. Specifically, the antenna gain was measured by setting a vertically polarized wave at the center of the turntable. Figure 1 The first antenna 1 and the second antenna 2 are mounted at the center of the vehicle 100. Furthermore, the antenna gain for the vertically polarized wave transmitted from the transmitting antenna fixed to the outside of the turntable is measured by varying the azimuth angle in the horizontal plane relative to the antenna.

[0087] Figure 12 This is the result (unit: dBi) of plotting the antenna gain of vertically polarized waves measured at 5.9 GHz when the azimuth angle is changed every 1° between 0° and 360° in Example 1. Figure 12 As shown, the vehicle antenna system 101 of this embodiment has a position where the gain is less than -5 [dBi] only at 90° between 0° and 360° in the horizontal plane of the vehicle 100 , and can ensure a predetermined antenna gain in the horizontal plane.

[0088] Comparative Example 1

[0089] Comparative Example 1 uses the same shapes of first antenna 1 and second antenna 2 as Example 1, but unlike Example 1, the first antenna 1 and second antenna 2 are positioned in the vehicle width direction on the vehicle center axis 50. That is, the first antenna 1 and second antenna 2 are both positioned across the vehicle center axis 50 in both area A and area B. Figure 13 1 is a schematic diagram showing the arrangement of the first antenna 1 and the second antenna 2 in the vehicle antenna system 101 of Comparative Example 1. The vertical mounting positions of the first antenna 1 and the second antenna 2 are the same as those of the first embodiment.

[0090] Figure 14 This is the result (unit: dBi) of plotting the antenna gain of vertically polarized waves measured at 5.9 GHz when the azimuth angle is changed every 1° between 0° and 360° in Comparative Example 1. Figure 14 As shown, the vehicle antenna system 101 of Comparative Example 1 has three locations with a gain less than -5 dBi between 0° and 360° in the horizontal plane of the vehicle 100, one near 90° and two near 270°, and thus cannot ensure the required antenna gain in the horizontal plane.

[0091] This international application claims the benefit of priority based on Japanese Patent Application No. 2020-053160, filed on March 24, 2020, the entire contents of which are incorporated herein by reference.

[0092] Description of labels

[0093] A area A;

[0094] B area B;

[0095] 1 first antenna;

[0096] 2 Second antenna;

[0097] 10 The range of half-value angles centered on the main beam;

[0098] 11 main beam;

[0099] 12 conductor plates;

[0100] 13 dielectric substrate;

[0101] 14 first surface;

[0102] 15 second surface;

[0103] 16 radiant panels;

[0104] 17 a first non-powered conductor plate;

[0105] 18 a second non-powered conductor plate;

[0106] 20 The range of half-value angles centered on the main beam;

[0107] 21 main beam;

[0108] 22 center of gravity;

[0109] 23 connection points;

[0110] 24 connecting conductors;

[0111] 25 Power Supply Department;

[0112] 26 center of gravity;

[0113] 50 vehicle center axis;

[0114] 60 anterior boundary line;

[0115] 70 posterior boundary line;

[0116] 100 vehicles;

[0117] 101 Vehicle antenna system;

[0118] 110 front windshield;

[0119] 111 anterior first area;

[0120] 112 anterior second area;

[0121] 120 rear windshield;

[0122] 121 posterior first area;

[0123] 122 posterior second area;

[0124] 130 rear spoiler;

[0125] 131 Vehicle lighting.

Claims

1. A vehicle antenna system comprising: A first antenna is installed near the front windshield of the vehicle; and A second antenna is installed near the rear windshield of the vehicle, The first antenna and the second antenna are capable of transmitting and receiving radio waves in a predetermined frequency band F. When viewed from a viewpoint in the normal direction of a horizontal plane, the region A and the region B are given by the vehicle center axis extending in the direction of travel of the vehicle and bisecting the vehicle width. The first antenna is configured in area A, and the second antenna is configured in area B. The angle formed by the direction of the main beam of the first antenna and the direction of the main beam of the second antenna when the vehicle is viewed from the normal direction of the horizontal plane is θ 12 When θ 12 is greater than 120° and less than 240°, When the vehicle is viewed from the side, the elevation angle of the main beam of the first antenna relative to the horizontal plane is α, and the elevation angle of the main beam of the second antenna relative to the horizontal plane is β, α and β are not less than -20° and not more than 60°.

2. The vehicle antenna system according to claim 1, wherein: Near the front windshield, the only antenna capable of transmitting and receiving the predetermined frequency band F is the first antenna. Near the rear windshield, the second antenna is the only antenna capable of transmitting and receiving the predetermined frequency band F.

3. The vehicle antenna system according to claim 1 or 2, wherein: Given a front boundary line perpendicular to the vehicle width direction of the front windshield in the region A when viewed from a viewpoint in the normal direction of the horizontal plane, The area between the front boundary line and the edge of the front windshield glass on the area A side is defined as a front first area. When the area between the vehicle center axis and the front boundary line is defined as the front second area, The first antenna is arranged in the first front area. When the width of the front first region and the width of the front second region in the vehicle width direction passing through the first antenna are respectively set to W F1 、W F2 hour, W F1 / (W F1 +W F2 ) satisfies 0.05 or more and 0.90 or less.

4. The vehicle antenna system according to claim 1 or 2, wherein: Given a rear boundary line perpendicular to the vehicle width direction of the rear windshield in the region B when viewed from a viewpoint in the normal direction of the horizontal plane, The area between the rear boundary line and the end edge of the rear windshield glass on the area B side is defined as the rear first area. When the area between the vehicle center axis and the rear boundary line is defined as the rear second area, The second antenna is arranged in the first rear area. When the width of the first rear region and the width of the second rear region in the vehicle width direction passing through the second antenna are respectively set to W R1 、W R2 When W R1 / (W R1 +W R2 ) satisfies 0.90 or less.

5. The vehicle antenna system according to claim 1 or 2, wherein: In the front view of the vehicle, the distance from the lowest position of the front windshield to the highest position of the roof of the vehicle in the normal direction of the horizontal plane is set as H F hour, The first antenna is arranged from the highest position of the roof to 0.5×H F range.

6. The vehicle antenna system according to claim 5, wherein: In the front view of the vehicle, the distance from the lowest position of the front windshield to the highest position of the front windshield in the normal direction of the horizontal plane is set as H GF hour, The first antenna is arranged from the highest position of the front windshield to 0.5×H GF range.

7. The vehicle antenna system according to claim 1 or 2, wherein: The distance from the lowest position of the rear windshield to the highest position of the roof of the vehicle in the normal direction of the horizontal plane is set as H R hour, The second antenna is arranged from the highest position of the roof to 0.5×H R range.

8. The vehicle antenna system according to claim 7, wherein: The second antenna is configured in an aerodynamic kit, which is installed closer to the outside of the vehicle than the rear windshield.

9. The vehicle antenna system according to claim 8, wherein: The aerodynamic kit is a spoiler.

10. The vehicle antenna system according to claim 1 or 2, wherein: The second antenna is arranged on the inner side of the rear windshield. The distance from the lowest position of the rear windshield to the highest position of the rear windshield in the normal direction of the horizontal plane is set as H GR hour, The second antenna is arranged from the highest position of the rear windshield to 0.5×H GR range.

11. The vehicle antenna system according to claim 1 or 2, wherein: At least one of the first antenna and the second antenna is a patch antenna.

12. The vehicle antenna system according to claim 1 or 2, wherein: The frequency band F includes 5.9 GHz.

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