Vehicle Antenna System

Abstract

A vehicle antenna system has a first antenna attached near the front windshield of a vehicle, and a second antenna attached near the rear windshield of the vehicle. The first antenna and the second antenna can transmit and receive electric waves in a prescribed frequency band F. In the viewpoint from the direction normal to a horizontal surface, the first antenna is arranged in a region A, and the second antenna is arranged in a region B, when the region A and the region B are given according to a vehicle center axis that extends in the travel direction of the vehicle and divides the vehicle width of the vehicle in two equal parts.

Description

[Technical field]

[0001] The present invention relates to a vehicle antenna system. [Background technology]

[0002] In recent years, there has been a trend toward the expansion of services that use high-speed, large-capacity wireless communication systems that use frequencies in the GHz (gigahertz) band, such as the transition from 4G LTE (800 MHz band) to 5G (sub6). Specifically, there is a trend toward expanding the bands used by such services from the 3 GHz band to the 5-6 GHz band. Furthermore, attempts are being made to popularize wireless communication systems that use frequency bands higher than sub6 (for example, the 28 GHz band, 40 GHz band, 60 GHz band, and 80 GHz band).

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

[0004] [Patent Document 1] International Publication No. 2019 / 208453 Summary of the Invention [Problem to be solved by the invention]

[0005] However, there is an increasing demand for achieving higher levels of both antenna gain and wider angle directivity all around the vehicle in the horizontal direction.

[0006] Therefore, the present disclosure provides a vehicle antenna system that can achieve both improved antenna gain and a wider angle of directivity in the horizontal plane. [Means for solving the problem]

[0007] The present disclosure provides an antenna system for a vehicle, comprising a first antenna mounted near the windshield of the vehicle and a second antenna mounted near the rear windshield of the vehicle, the first antenna and the second antenna being capable of transmitting and receiving radio waves in a predetermined frequency band F, and in a viewpoint normal to a horizontal plane, when areas A and B are defined by a vehicle center axis extending in the direction of travel of the vehicle and dividing the vehicle width in half, the first antenna is disposed in area A and the second antenna is disposed in area B. Effect of the Invention

[0008] According to the technique of the present disclosure, it is possible to provide a vehicle antenna system that can achieve both improved antenna gain and a wider angle of directivity in the horizontal plane. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram showing an example of a vehicle equipped with a vehicle antenna system as viewed from above. [Diagram 2] FIG. 4 is a diagram showing an example of the directivity of each antenna when viewed from above the vehicle. [Diagram 3] FIG. 2 is a diagram showing an example of the directivity of each antenna in the vertical plane. [Figure 4] FIG. 2 is a diagram showing an example of an antenna disposed near a windshield when viewed from above a vehicle. [Diagram 5] 1 is a diagram showing an example of an antenna disposed near a windshield when viewed from the front of a vehicle. [Figure 6] FIG. 2 is a diagram showing an example of an antenna disposed near a rear window when viewed from above a vehicle. [Figure 7] FIG. 2 is a diagram showing an example of an antenna disposed near a rear window when viewed from the rear of a vehicle. [Figure 8] 11 is a diagram showing another example of an antenna disposed near a rear window when viewed from the rear of the vehicle. FIG. [Figure 9] FIG. 2 is a schematic perspective view of an antenna. [Figure 10]FIG. 2 is a schematic cross-sectional view of the antenna taken along line α-α'. [Figure 11] FIG. 3 is a schematic cross-sectional view of the antenna taken along the line β-β'. [Figure 12] FIG. 11 is a diagram showing the measurement results of antenna gain in the horizontal direction in the first embodiment. [Figure 13] 1 is a top view of a vehicle equipped with a vehicle antenna system in a first comparative example. FIG. [Figure 14] FIG. 13 is a diagram showing the measurement results of antenna gain in the horizontal direction in Comparative Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments of the present disclosure will be described with reference to the drawings. In each embodiment, deviations in the directions such as parallel, right angle, orthogonal, horizontal, vertical, up / down, left / right, etc., are allowed to a degree that does not impair the effects of the present invention. In addition, the X-axis direction, the Y-axis direction, and the Z-axis direction respectively represent directions parallel to the X-axis, the Y-axis direction, and the Z-axis direction. The X-axis direction, the Y-axis direction, and the Z-axis direction are mutually orthogonal. The XY plane, the YZ plane, and the ZX plane respectively represent imaginary planes parallel to the X-axis direction and the Y-axis direction, imaginary planes parallel to the Y-axis direction and the Z-axis direction, and imaginary planes parallel to the Z-axis direction and the X-axis direction.

[0011] The vehicle antenna system according to the present disclosure will be described mainly as a system capable of transmitting and receiving radio waves in the sub6 (less than 6 GHz) frequency band in the fifth generation mobile communication system (5G), but is not limited to sub6. The vehicle antenna system according to the present disclosure may also be a system capable of transmitting and receiving radio waves in the SHF (Super High Frequency) band of 3 GHz to 30 GHz in 5G, and further in the EHF (Extremely High Frequency) band of 30 GHz to 300 GHz, which is a so-called millimeter wave.

[0012] Fig. 1 is a diagram showing an example of a vehicle equipped with a vehicle antenna system according to an embodiment of the present disclosure, viewed from above. The view from above corresponds to a viewpoint from a normal direction of a horizontal plane (ground). The vehicle antenna system 101 shown in Fig. 1 is an example of a vehicle antenna system including a plurality of antenna sets provided on dielectrics on both the front and rear sides of a vehicle 100 or in the vicinity thereof. Examples of the dielectrics include glass and resin.

[0013] In each drawing, the X-axis direction corresponds to the width direction of the vehicle 100, the Y-axis direction corresponds to the front-rear direction (traveling direction) of the vehicle 100, and the Z-axis direction corresponds to the up-down direction of the vehicle 100. The XY plane corresponds to the horizontal plane, and the Z-axis direction corresponds to the normal direction (vertical direction) to the horizontal plane.

[0014] 1 is a schematic diagram of a vehicle antenna system 101 showing an example of an arrangement of multiple antennas provided near the front and rear window glasses of a vehicle 100. A first antenna 1 is provided near a windshield 110, which is a dielectric material, at the front side of the vehicle 100, and a second antenna 2 is provided near a rear window 120, which is a dielectric material, at the rear side of the vehicle 100.

[0015] 1, a virtual line parallel to the Y-axis direction passing through the center of the vehicle 100 in the vehicle width direction, which is the X-axis direction, is defined as a vehicle center axis 50. The vehicle 100 is divided into two areas, area A and area B, with the vehicle center axis 50 as a boundary. More specifically, the first antenna 1 is installed in area A near the interior side of the windshield 110. Note that "the first antenna 1 is installed in area A" specifically refers to the fact that a conductor (conductor surface) for transmitting and receiving radio waves by the antenna 1 is arranged in area A, and does not include, for example, a housing supporting the conductor. In other words, in this case, only a part of the housing that supports the first antenna 1 and does not contribute to transmitting and receiving radio waves may be arranged in area B.

[0016] Moreover, the second antenna 2 is installed in region B. More specifically, the second antenna 2 is installed near the inside of the vehicle interior of the rear window 120 or near the outside of the vehicle interior of the rear window 120. Here, the vicinity of the outside of the vehicle interior includes an arrangement in which the second antenna 2 is mounted inside a rear window part, for example, when the vehicle 100 has an aero part (exterior part) such as a rear spoiler at approximately the same height as the roof and is attached to the outside of the vehicle near the rear window 120. Furthermore, as with the first antenna 1, "the second antenna 2 is installed in region B" means that a conductor (conductor surface) for transmitting and receiving radio waves from the second antenna 2 is arranged in region B, and for example, only a part of a housing that supports the conductor and does not contribute to transmitting and receiving radio waves may be arranged in region A.

[0017] The first antenna 1 and the second antenna 2 are formed to be capable of transmitting and receiving radio waves in a predetermined frequency band included in the range of, for example, 3 GHz to 100 GHz. Furthermore, the first antenna 1 and the second antenna 2 can transmit and receive radio waves in a predetermined frequency band F included in the above range. For example, when the vehicular antenna system 101 has a frequency band F including 5.9 GHz, the predetermined band can be in the range of 5.850 GHz to 5.925 GHz, and in this case, the system can be applied to V2X (Vehicle to Everything) and C-V2X (Cellular Vehicle to Everything) such as vehicle-to-vehicle communications.

[0018] Furthermore, if the only antenna that transmits and receives radio waves in a predetermined frequency band F near the windshield 110 is the first antenna 1, and the only antenna that transmits and receives radio waves in a predetermined frequency band F near the rear windshield 120 is the second antenna 2, this simplifies the vehicle antenna system 101 and is preferable.

[0019] FIG. 2 is a schematic diagram of a vehicle antenna system 101 showing different directions of main beams 11, 21 of the first antenna 1 and the second antenna 2 when the vehicle 100 is viewed from the normal direction of the horizontal plane. The main beams 11, 21 refer to beams in the direction in which radio waves of a predetermined frequency band can be most strongly transmitted and received. The directions of the main beams 11, 21 refer to both vector directions when radio waves are transmitted from the first antenna 1 and the second antenna 2, or both vector directions when radio waves are received by the first antenna 1 and the second antenna 2. In FIG. 2, 10 and 20 respectively represent the ranges of half-value angles centered on the main beams 11, 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, in FIG. 2, when the vehicle 100 is viewed from the normal direction of the horizontal plane, the directions of the main beams 11, 21 formed by the first antenna 1 and the second antenna 2 correspond to approximately the central angles of the half-power angle ranges 10, 20 centered on each main beam.

[0020] In this way, 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 when the vehicle 100 is viewed from the normal direction of the horizontal plane, the reception sensitivity of radio waves arriving from all directions in all directions centered on the vehicle 100 can be improved.

[0021] In addition, the angle 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 the vehicle 100 is viewed from the normal direction of the horizontal plane is θ 12 In this case, the angle θ 12 The angle θ may 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 in such a range, the receiving sensitivity of the vehicle antenna system 101 to radio waves arriving from all directions in all directions can be further improved.

[0022] 3 is a schematic diagram showing half-angle ranges 10, 20 centered on the main beams 11, 21 of the first antenna 1 and the second antenna 2, respectively, when the vehicle 100 is viewed from the side (YZ plane). In FIG. 3, the angle (elevation angle) of the main beam 11 with respect to the horizontal plane 90 is α, and the angle (elevation angle) of the main beam 21 with respect to the horizontal plane is β. In this case, for example, by setting the elevation angles α and β to an angle range of -20° or more and 60° or less, the reception sensitivity of radio waves arriving from above and below the vehicle 100 can be improved. Moreover, the elevation angles α and β are preferably in an angle range of -10° or more and 40° or less, and more preferably in an angle range of -5° or more and 20° or less.

[0023] Next, the detailed arrangement of the first antenna 1 will be described. Fig. 4 is an enlarged schematic diagram showing a portion of the vehicle 100 including the windshield 110 when the vehicle 100 is viewed from the normal direction of the horizontal plane. First, the distance in the vehicle width direction of the windshield 110 passing through the first antenna 1 is defined as W F Then, the vehicle width direction distance in area A is W F / 2. If region A is divided by a front-side boundary line 60, which is approximately perpendicular to the vehicle width direction of windshield 110, into a front-side first region 111 on the edge side (metal frame, for example, A-pillar) side of windshield 110 and a front-side second region 112 on the vehicle center axis 50 side, the first antenna 1 is disposed in front-side first region 111.

[0024] In other words, the front-side boundary line 60 is an imaginary line that passes through the end of the first antenna 1 opposite to the edge side of the windshield 110 and extends in a direction approximately perpendicular to the vehicle width direction. The front-side boundary line 60 divides the windshield 110 arranged in the area A into a front-side first area 111 and a front-side second area 112. Here, the distance in the vehicle width direction that passes through the first antenna 1 in the front-side first area 111 is defined as W F1 Let W F1 The distance in the vehicle width direction in the front side second region 112 on the extension line of F2 In this case, W F1 / (W F1 +W F2The first antenna 1 should be arranged so that W is between 0.05 and 0.90. F / 2=W F1 +W F2 This is the relationship.

[0025] Here, W F1 / (W F1 +W F2 If W ) exceeds 0.90, the reception sensitivity of the first antenna 1 in the vehicle width direction of the vehicle 100 may decrease. F1 / (W F1 +W F2 If W ) exceeds 0.90, the first antenna 1 may be placed, for example, near the rearview mirror and close to the housing that houses the camera, rain sensor, etc., making it physically impossible to place it there, or it may interfere with the camera, etc., generating unnecessary noise. F1 / (W F1 +W F2 If W is less than 0.05, the first antenna 1 may come close to the metal frame (A-pillar) of the body of the vehicle 100, which may reduce the antenna gain. F1 / (W F1 +W F2 ) is preferably 0.10 or more and 0.80 or less, and more preferably 0.10 or more and 0.70 or less.

[0026] 5 is a schematic diagram of the vehicle 100 as viewed from the front, that is, as viewed from the Y-axis direction (XZ plane). Note that the vehicle center axis 50 is omitted in FIG. 5, but the left side of the line (in the Z-axis direction) along the center of the vehicle 100 in the vehicle width direction is area A, and the right side is area B. In FIG. 5, the highest position V of the roof when viewed from the front of the vehicle 100 is R From the lowest position of the windshield 110 F B The distance in the normal direction of the horizontal plane, that is, the vertical direction (Z-axis direction) F At this time, the first antenna 1 is located at a position V R From 0.5×H F The first antenna 1 should be placed within the position V R From 0.5×H FIf the first antenna 1 is placed at a position V, the visibility of the occupants of the vehicle 100 may be obstructed more than necessary, and the antenna gain may be reduced due to the influence of the ground, the vehicle hood, etc. R From 0.4×H F It is preferable to place it within the V R From 0.3×H F It is more preferable to place it within

[0027] In addition, in FIG. 5, the highest position F of the windshield 110 in a front view of the vehicle 100 is T From the lowest position of the windshield 110 F B The distance in the normal direction of the horizontal plane, that is, the vertical direction (Z-axis direction) GF At this time, the first antenna 1 is located at a position F T From 0.5×H GF The first antenna 1 should be placed within the position F T From 0.5×H GF If the first antenna 1 is disposed at a position F, the visibility of the occupants of the vehicle 100 may be obstructed more than necessary, and the antenna gain may be reduced due to the influence of the ground, the vehicle hood, etc. T From 0.4×H GF It is preferable to place it within the F T From 0.3×H GF It is more preferable to place the first antenna 1 within the position F T The height of the first and second electrodes may be adjacent to each other.

[0028] Next, the detailed arrangement of the second antenna 2 will be described. Fig. 6 is an enlarged schematic diagram showing a portion of the vehicle 100 including the rear window 120 when the vehicle 100 is viewed from the normal direction of the horizontal plane. First, the distance of the rear window 120 passing through the second antenna 2 in the vehicle width direction is defined as W. R Then, the vehicle width direction distance in area B is W R / 2. If region B is divided by rear-side boundary line 70, which is approximately perpendicular to the vehicle width direction of rear glass 120, into a rear-side first region 121 on the edge (metal frame (e.g., C-pillar)) side of rear glass 120 and a rear-side second region 122 on the vehicle center axis 50 side, second antenna 2 is disposed in rear-side first region 121.

[0029] In other words, the rear-side boundary line 70 passes through the end of the second antenna 2 opposite to the end side of the rear glass 120, and extends in a direction approximately perpendicular to the vehicle width direction. The rear-side boundary line 70 divides the rear glass 120 arranged in the region B into a rear-side first region 121 and a rear-side second region 122. Here, the distance in the vehicle width direction passing through the second antenna 2 in the rear-side first region 121 is defined as W R1 Let W R1 The distance in the vehicle width direction in the rear side second region 122 on the extension line of R2 In this case, W R1 / (W R1 +W R2 The second antenna 2 should be arranged so that W is 0.90 or less. R / 2=W R1 +W R2 This is the relationship.

[0030] W R1 / (W R1 +W R2 If W ) exceeds 0.90, the reception sensitivity of the second antenna 2 in the vehicle width direction of the vehicle 100 may decrease. R1 / (W R1 +W R2 If W exceeds 0.90, the second antenna 2 may obstruct the rear view, or may be physically difficult to install due to being too close to vehicle lighting such as high-mounted stop lamps, or may interfere with a rear camera in the case of a vehicle equipped with such a camera, resulting in unwanted noise. R1 / (W R1 +W R2 ) is preferably 0.80 or less, more preferably 0.70 or less.

[0031] Also, W R1 / (W R1 +W R2 When the second antenna 2 is provided near the inside of the rear window 120, W is preferably 0.05 or more, and more preferably 0.10 or more. R1 / (W R1 +W R2 If W is less than 0.05, the second antenna 2 may come close to the metal frame (e.g., C-pillar) of the body of the vehicle 100, which may reduce the antenna gain. In addition, when the second antenna is mounted inside an aerodynamic part such as the rear spoiler described above, W R1 / (W R1 +W R2 ) can be disposed in a portion protruding rearward from the metal frame of the vehicle 100, so the lower limit is not limited to 0.05 or more and 0.90 or less, and may be less than 0.05 or 0.03 or less. R1 / (W R1 +W R2 ) is less than 0.05, for example, may be in the range of 0.01 or more and 0.04 or less.

[0032] 7 is a schematic diagram of the vehicle 100 as seen from the rear, that is, as seen from the Y-axis direction (XZ plane). Note that the vehicle center axis 50 is omitted in FIG. 7, but the right side of the line (Z-axis direction) along the center of the vehicle 100 in the vehicle width direction is area A, and the left side is area B. In FIG. 7, the highest position V of the roof in the rear view of the vehicle 100 is R From the lowest position of the rear window 120 R B The distance in the normal direction of the horizontal plane, that is, the vertical direction (Z-axis direction) R At this time, the second antenna 2 is located at a position V R From 0.5×H R The second antenna 2 should be placed within the position V R From 0.5×H R If the second antenna 2 is placed at a position V, the field of view of the vehicle 100 may be blocked more than necessary, and the antenna gain may be reduced due to the influence of the ground, the vehicle body, etc. R From 0.4×H R It is preferable to place it within the VR From 0.3×H R It is more preferable to place it within

[0033] In addition, in FIG. 7, the highest position R of the rear window 120 in a rear view of the vehicle 100 T From the lowest position of the rear window 120 R B The distance in the normal direction of the horizontal plane, that is, the vertical direction (Z-axis direction) GR At this time, the second antenna 2 is located at a position R T From 0.5×H GR The second antenna 2 should be placed within the position R T From 0.5×H GR If the second antenna 2 is disposed at a position beyond the position R, the visibility of the occupants of the vehicle 100 may be obstructed more than necessary, and the antenna gain may be reduced due to the influence of the ground, the vehicle body, etc. T From 0.3×H GR It is preferable to place it within the position R T From 0.1 × H GR It is more preferable to place it within

[0034] 7 shows an example of a vehicle 100 having a rear spoiler 130 that protrudes toward the rear of the vehicle 100 (negative Y-axis direction) above the rear window 120 along the inclination direction of the roof. The rear spoiler 130 may also have a vehicle lamp 131 such as a high-mounted stop lamp at the center in the vehicle width direction. When the rear window 120 has a part hidden by the rear spoiler 130 and a part exposed to the outside of the vehicle in the rear view of FIG. 7, the position R of the rear window 120 may be a position where the rear window 120 is exposed. T is the highest position at which the rear window 120 is exposed to the vehicle exterior. In this case, the vehicle 100 in FIG. 7 is at the position R T However, in this example, it is hidden by the rear spoiler 130 when viewed from the rear.

[0035] At this time, the second antenna 2 is located at a position R T From 0.5×H GRThe second antenna 2 should be placed within the position R T From 0.5×H GR If the second antenna 2 is disposed at a position beyond the position R, the visibility of the occupants of the vehicle 100 may be obstructed more than necessary, and the antenna gain may be reduced due to the influence of the ground, the vehicle body, etc. T From 0.3×H GR It is preferable to place it within the position R T From 0.1 × H GR It is more preferable to place it within

[0036] 8 is a schematic diagram of the vehicle 100 as viewed from the rear, that is, as viewed from the Y-axis direction (XZ plane), and is the same as the vehicle 100 shown in FIG. 7 except that it does not have a rear spoiler 130, which is an example of an aerodynamic part. In this case, the second antenna 2 is also located at a position V, depending on the specifications of the vehicle 100. R From 0.5×H R It is recommended to place it within position V R From 0.3×H R It is preferable to place it within the V R From 0.1 × H R It is more preferable to place it within

[0037] In addition, in FIG. 8, the highest position R of the rear window 120 in a rear view of the vehicle 100 T From the lowest position of the rear window 120 R B The distance in the normal direction of the horizontal plane, that is, the vertical direction (Z-axis direction) GR At this time, the second antenna 2 is located at a position R T From 0.5×H GR The second antenna 2 should be placed within the position R T From 0.5×H GR If the second antenna 2 is disposed at a position beyond the position R, the visibility of the occupants of the vehicle 100 may be obstructed more than necessary, and the antenna gain may be reduced due to the influence of the ground, the vehicle body, etc. T From 0.3×H GR It is preferable to place it within the position R T From 0.1 × HGR It is more preferable to place it within

[0038] Next, the first antenna 1 and the second antenna 2 will be described. The first antenna 1 and the second antenna 2 may be antennas of the same shape or different shapes as long as they can transmit and receive a predetermined frequency F. Also, the first antenna 1 and the second antenna 2 may be formed to transmit and receive a predetermined polarized wave. For example, the first antenna 1 and the second antenna 2 may be formed to transmit and receive mainly vertically polarized waves, may be formed to transmit and receive mainly horizontally polarized waves, or may be formed to transmit and receive both vertically polarized waves and horizontally polarized waves with high sensitivity. FIG. 9 is a schematic perspective view showing an example of the first antenna 1, FIG. 10 is a schematic cross-sectional view of the first antenna 1 taken along α-α' (dashed line) in FIG. 9, and FIG. 11 is a schematic cross-sectional view of the first antenna 1 taken along β-β' (dashed line) in FIG. 9. The first antenna 1 shown in FIGS. 9 to 11 is a so-called patch antenna, but the first antenna 1 is not limited thereto. 9 are imaginary lines that pass through center of gravity 22 of radiation plate 16 and are perpendicular to each other.

[0039] 9 to 11, the first antenna 1 has a radiating plate 16, a first parasitic conductive plate 17 and a second parasitic conductive plate 18 on a first surface 14 of a dielectric substrate 13, and has a conductive plate 12 on a second surface 15 of the dielectric substrate 13.

[0040] The radiation plate 16 is a plate-like or film-like conductor arranged opposite the conductive plate 12 in the Y-axis direction, and has an area smaller than that of the conductive plate 12. The surface of the radiation plate 16 is a planar layer parallel to the XZ plane, and functions as a radiating element of the first antenna 1. Examples of conductor materials used for the radiation plate 16 include, but are not limited to, silver and copper. The shape of the radiation plate 16 is a square, but it may be a polygon other than a square, or another shape such as a circle.

[0041] The radiation plate 16 is disposed away from the conductive plate 12. The medium between the conductive plate 12 and the radiation plate 16 includes at least one of a space and a dielectric substrate. Figures 9 and 10 show a case where the medium is made of only the dielectric substrate 13. The dielectric substrate 13 is a plate-shaped or film-shaped dielectric layer whose main component is a dielectric. The dielectric substrate 13 has a first surface 14 and a second surface 15 opposite to the first surface 14. The first surface 14 and the second surface 15 are parallel to the XZ plane. The radiation plate 16 is provided on the first surface 14 of the dielectric substrate 13, and the conductive plate 12 is provided on the second surface 15.

[0042] The dielectric substrate 13 may be, for example, a dielectric substrate such as a glass epoxy substrate, or may be 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.

[0043] In the first antenna 1 shown in Fig. 10, the power supply unit 25 is a portion to which power is supplied in a contact or non-contact manner, and is a portion to which one end of a power supply line (not shown) is connected or in close proximity. Specific examples of the power supply line include 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 radiation plate 16 where the conductor plate 12 is arranged.

[0044] The connecting conductor 24 is not in contact with the conductive plate 12. One end of the connecting conductor 24 is connected to the power supply unit 25, and the other end is connected to the radiation plate 16 at a connection point 23. The connection point 23 is offset from the center of gravity 22 of the radiation plate 16, and in the illustrated example, is located on the negative side of the Z-axis direction with respect to the center of gravity 22. When the radiation plate 16 is a symmetrical shape such as a square, the center of gravity 22 corresponds to the center of the symmetrical shape.

[0045] Specific examples of the connecting conductor 24 include a conductor formed inside a through-hole penetrating the dielectric substrate 13 in the Y-axis direction, a core wire of a coaxial cable, and a pin-shaped conductor pin, but the connecting conductor 24 is not limited to these. When the medium between the conductor plate 12 and the radiation plate 16 includes a space, specific examples of the connecting conductor 24 include a core wire or conductor pin of a coaxial cable, but the connecting conductor 24 is not limited to these.

[0046] 10, when viewed from the radiation plate 16 side with respect to the conductor plate 12, it is preferable that the center of gravity 22 of the radiating plate 16 overlaps with the center of gravity 26 of the conductor plate 12 in order to improve 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 with respect 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.

[0047] 9 and 11, the first parasitic conductive plate 17 and the second parasitic conductive plate 18 are conductors arranged on both sides of the radiation plate 16 in the vehicle width direction (X-axis direction) of the vehicle, spaced apart from each other. By arranging the first parasitic conductive plate 17 and the second parasitic conductive plate 18 in this manner, the antenna gain of the first antenna 1 in the vehicle width direction is improved. Note that the first antenna 1 may or may not include the first parasitic conductive plate 17 and the second parasitic conductive plate 18. When the first antenna 1 includes the first parasitic conductive plate 17 and the second parasitic conductive plate 18, the antenna gain in the X-axis direction is relatively larger than when they are not included.

[0048] At least one of the first parasitic conductive plate 17 and the second parasitic 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 reflector element of the first antenna 1. In this example, the first parasitic conductive plate 17 and the second parasitic conductive plate 18 are arranged on the same layer as each other, and are located away from the center of gravity 22 of the radiating plate 16 when viewed from the perspective of the radiating plate 16 side with respect to the conductor plate 12.

[0049] In this example, the first parasitic conductive plate 17 and the second parasitic conductive plate 18 each have an area smaller than that of the conductive plate 12 and the radiating plate 16, but the area is not limited to this. For example, at least one of the first parasitic conductive plate 17 and the second parasitic conductive plate 18 may have an area larger than that of the radiating plate 16.

[0050] Examples of conductor materials used for the first parasitic conductive plate 17 and the second parasitic conductive plate 18 include, but are not limited to, silver and copper. In addition, the illustrated first parasitic conductive plate 17 and the second parasitic conductive plate 18 are rectangular in shape, but may be polygonal other than rectangular or may be other shapes such as a circle.

[0051] When viewed from the radiation plate 16 side relative to the conductor plate 12, the first parasitic conductor plate 17 and the second parasitic conductor plate 18 are preferably shaped symmetrically about an axis of symmetry passing through a connection point 23 where the connecting conductor 24 is connected to the radiation plate 16 in terms of improving the antenna gain of the first antenna 1. In this example, the antenna gain of the first antenna 1 is improved in the X-axis direction.

[0052] As described above, the second antenna 2 may have the same shape as the first antenna 1, or may have a different shape. When the second antenna 2 has the same shape as the first antenna 1, the second antenna 2 has a configuration in which the positive and negative directions in the Y-axis direction are reversed from those of the first antenna 1 shown in Figures 9 to 11. In other words, the second antenna 2 has the same configuration as the first antenna 1, except that the direction from the conductor plate 12 toward the radiation plate 16 is the negative Y-axis direction.

[0053] 1, the vehicle antenna system 101 including the first antenna 1 and the second antenna 2 has the first antenna 1 disposed near the windshield 110 and the second antenna 2 disposed near the rear window 120, as described above. When the first antenna 1 and the second antenna 2 are patch antennas as shown in FIGS. 9 to 11, the surface of the radiation plate 16 can be disposed parallel to the XZ plane, but is not limited to such an arrangement.

[0054] In Fig. 1, the surface of the radiating plate 16 of the first antenna 1 may be inclined with respect to the XZ plane. For example, the surface of the radiating plate 16 of the first antenna 1 may be inclined from the X-axis direction (vehicle width direction) in a direction perpendicular to the horizontal plane. In this case, the angle (γ y1 ) may be tilted in the range of -15° to +15°. This arrangement can also be applied to the second antenna 2 if it has the same shape as the first antenna 1.

[0055] 1, the surface of the radiation plate 16 of the first antenna 1 may be inclined with respect to the XY plane. In this case, the angle (γ y2 ) may be tilted in the range of -15° to +15°. This arrangement can also be applied to the second antenna 2 if it has the same shape as the first antenna 1.

[0056] In this manner, in the vehicle antenna system 101 according to the present embodiment, if the first antenna 1 is disposed in the area A near the windshield 110 and the second antenna 2 is disposed in the area B near the rear windshield 120, the normal direction of the surface of the radiation plate 16 of each antenna (the first antenna 1 and the second antenna 2) is set at, for example, the above-mentioned angle γ y1 , γ y2 The first antenna 1 and the second antenna 2 may be attached to the glass plate on the inside of the vehicle of the windshield 110 and the rear window 120 via a predetermined housing, or may be attached to the ceiling on the inside of the vehicle via a predetermined housing.

[0057] Furthermore, in the vehicle antenna system 101 of this embodiment, in addition to the first antenna 1 and the second antenna 2, an antenna capable of transmitting and receiving a frequency band different from frequency band F may be arranged near at least one of the windshield 110, the rear window 120, and the side window (fixed window glass).

[0058] <Example 1> In Example 1, a first antenna 1 shown in Fig. 9 was fabricated, and a second antenna 2 having the same shape as the first antenna 1 was mounted on a vehicle 100 to realize a vehicle antenna system 101. Specifically, the first antenna 1 had the following dimensions (unit: mm). A fluororesin substrate was used as the material for the dielectric base material 13, and copper was used as the material for the radiation plate 16, the first parasitic conductor plate 17, the second parasitic conductor plate 18, and the conductor plate 12.

[0059] L12:22 L13:18 L14:16 L15:2 L16:24 L17:29

[0060] The fabricated first antenna 1 was placed in an area A near the windshield 110, and the second antenna 2 was placed in an area B near the rear window. At this time, the surfaces of the radiation plates 16 of the first antenna 1 and the second antenna 2 were attached so as to be parallel to the XZ plane (vehicle width direction). Furthermore, the first antenna 1 was placed in the front first area 111, and specifically, the attachment position in the vehicle width direction was set to be W F1 / (W F1 +W F2 ) was set to 0.6. The first antenna 1 was attached at the highest position on the roof V R From 0.2 × H F , the highest position of the windshield 110 F T From 0.05×H GF At this time, the angle α of the main beam 11 with respect to the horizontal plane of the first antenna 1 was approximately 0°.

[0061] The second antenna 2 is disposed in the rear first region 121. Specifically, the second antenna 2 is attached at a position W R1 / (W R1 +W R2 ) was set to 0.2. The second antenna 2 was installed at the highest position V R From 0.2 × H R , rear window 120R T From 0.05×HGR In this case, the angle β of the main beam 21 of the second antenna 2 with respect to the horizontal plane was approximately 0°. Note that 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 (Z-axis direction) of the horizontal plane was approximately 0°. 12 was set to approximately 180°.

[0062] In the vehicle antenna system 101 of Example 1, the antenna characteristics of vertically polarized waves at 5.9 GHz included in the predetermined frequency band F were measured. Specifically, the antenna gain was measured by setting the center of the vehicle 100, on which the first antenna 1 and the second antenna 2 were attached as shown in Fig. 1, at the center of a turntable. Then, for the vertically polarized waves transmitted from a transmitting antenna fixed to the outside of the turntable, the azimuth angle in the horizontal plane with the antenna was changed to measure the antenna gain for the vertically polarized waves.

[0063] Fig. 12 is a plot of antenna gain (unit: dBi) of vertical polarization measured at 5.9 GHz when the azimuth angle is changed in 1° increments from 0° to 360° in Example 1. As shown in Fig. 12, in the vehicle antenna system 101 in this example, there is only one position near 90° where the gain is less than -5 [dBi] across 0° to 360° in the horizontal plane of the vehicle 100, and a predetermined antenna gain was ensured across the horizontal plane.

[0064] <Comparative Example 1> In Comparative Example 1, the first antenna 1 and the second antenna 2 having the same shape as in Example 1 were used, but the positions of the first antenna 1 and the second antenna 2 in the vehicle width direction were arranged on the vehicle central axis 50, unlike in Example 1. In other words, the first antenna 1 and the second antenna 2 were arranged in both areas A and B across the vehicle central axis 50. FIG. 13 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 mounting positions of the first antenna 1 and the second antenna 2 in the vertical direction were the same as in Example 1.

[0065] Fig. 14 is a plot of antenna gain (unit: dBi) of vertical polarization measured at 5.9 GHz when the azimuth angle is changed in 1° increments from 0° to 360° in Comparative Example 1. As shown in Fig. 14, in the vehicle antenna system 101 in Comparative Example 1, there were three positions where the gain was less than -5 [dBi] across 0° to 360° in the horizontal plane of the vehicle 100: one position near 90° and two positions near 270°, and the predetermined antenna gain could not be ensured across the horizontal plane.

[0066] This international application claims priority to Japanese Patent Application No. 2020-053160, filed on March 24, 2020, the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0067] A area A B Area B 1 First Antenna 2 Second Antenna 10 Half-power angle range centered on the main beam 11 Main beam 12 Conductor plate 13 Dielectric substrate 14 1st surface 15 Second surface 16 Radiation plate 17 First parasitic conductor plate 18 Second parasitic conductor plate 20 Half-power angle range centered on the main beam 21 Main beam 22 Center of gravity 23 Connection points 24 Connecting conductor 25 Power supply unit 26 Center of gravity 50 Vehicle center axis 60 Front border 70 Rear boundary line 100 vehicles 101 Vehicle antenna system 110 Windshield 111 Front side first area 112 Front side second area 120 Rear glass 121 Rear first area 122 Rear second area 130 Rear spoiler 131 Vehicle lighting fixtures

Claims

1. a first antenna mounted near a windshield of the vehicle; a second antenna mounted near a rear window of the vehicle; The first antenna and the second antenna can transmit and receive radio waves in a predetermined frequency band F, When an area A and an area B are given by a vehicle center axis extending in the traveling direction of the vehicle and dividing the vehicle width in half, from a viewpoint normal to a horizontal plane, The first antenna is disposed in an area A, and the second antenna is disposed in an area B, When the vehicle is viewed from a normal direction to a horizontal plane, an angle between a direction of a main beam of the first antenna and a direction of a main beam of the second antenna is defined as θ 12 , and θ 12 is equal to or greater than 120° and equal to or less than 240°; A vehicle antenna system, wherein when the vehicle is viewed from the side, an elevation angle of the main beam of the first antenna with respect to a horizontal plane is α, and an elevation angle of the main beam of the second antenna with respect to the horizontal plane is β, and α and β are greater than or equal to -20° and less than or equal to 60°.

2. the first antenna is the only antenna capable of transmitting and receiving the predetermined frequency band F in the vicinity of the windshield, the second antenna is the only antenna capable of transmitting and receiving the predetermined frequency band F in the vicinity of the rear window; 2. A vehicle antenna system according to claim 1.

3. A front side boundary line perpendicular to the vehicle width direction of the windshield in the region A is given in a view from a normal direction of a horizontal plane, A region between the front-side boundary line and an end side of the windshield on the region A side is defined as a front-side first region, When a region between the vehicle center axis and the front-side boundary line is defined as a front-side second region, The first antenna is disposed in a front first region, The width of the front-side first region and the width of the front-side second region in the vehicle width direction passing through the first antenna are each defined as W Ｆ１ , W Ｆ２ When W Ｆ１ / (W Ｆ１ +W Ｆ２ 3. The vehicle antenna system according to claim 1, wherein the ratio of the azimuth angle to the azimuth angle satisfies 0.05 to 0.

90.

4. A rear side boundary line perpendicular to the vehicle width direction of the rear glass in the region B is given in a view from a normal direction of a horizontal plane, A region between the rear-side boundary line and an end side of the rear glass on the region B side is defined as a rear-side first region, When a region between the vehicle center axis and the rear side boundary line is defined as a rear side second region, The second antenna is disposed in a rear first region, The width of the rear first region and the width of the rear second region in the vehicle width direction passing through the second antenna are each defined as W Ｒ１ , W Ｒ２ Then, W Ｒ１ / (W Ｒ１ +W Ｒ２ 4. The vehicle antenna system according to claim 1, wherein the ratio of the azimuth angle to the azimuth angle satisfies 0.90 or less.

5. When viewed from the front of the vehicle, the distance from the lowest point of the windshield to the highest point of the roof of the vehicle in the normal direction to the horizontal plane is defined as H. Ｆ When The first antenna is located 0.5×H from the highest point of the roof. Ｆ 5. The vehicle antenna system according to claim 1, wherein the vehicle antenna system is arranged in a range of from 0 to 400 mm.

6. When the vehicle is viewed from the front, the distance from the lowest position of the windshield to the highest position of the windshield in the normal direction to the horizontal plane is defined as HGF.

6. The vehicle antenna system according to claim 5, wherein the first antenna is disposed within a range of 0.5×HGF from a highest position of the windshield.

7. The distance from the lowest point of the rear window to the highest point of the roof of the vehicle in the normal direction of the horizontal plane is H. Ｒ When The second antenna is located 0.5×H from the highest point of the roof. Ｒ 7. A vehicle antenna system according to claim 1, wherein the vehicle antenna system is arranged in a range of from 0 to 1000 mm.

8. The vehicle antenna system according to claim 7 , wherein the second antenna is disposed within an aerodynamic part attached to an outer side of the vehicle than the rear window.

9. 9. The vehicle antenna system according to claim 8, wherein the aero part is a spoiler.

10. The second antenna is disposed on an inner side of the rear window, When the distance from the lowest position of the rear glass to the highest position of the rear glass in the normal direction of the horizontal plane is HGR, 10. The vehicle antenna system according to claim 1, wherein the second antenna is disposed within a range of 0.5×HGR from a highest position of the rear window.

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

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

Images