JP2019134287A - Antenna system, vehicle, and spoiler - Google Patents

Abstract

To provide a technique that improves the antenna gain of an on-vehicle antenna device mounted on the roof of a vehicle.SOLUTION: A conductor 34 is attached in an area at a distance L2 from an antenna element 33 of an on-vehicle antenna device 32 of a spoiler 20 (portion serving as an insulator) located at a rear of the on-vehicle antenna device 32 installed on the roof 12 of a vehicle 10. The distance L2 is three or more and five or less times a wavelength λ relating to the communication frequency of the on-vehicle antenna device 30.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an antenna system and the like mounted on a vehicle.

  As an in-vehicle antenna device attached to a roof of a vehicle such as an automobile, an antenna device in which an antenna element is housed in a streamline case considering air resistance during traveling is known. This type of vehicle-mounted antenna device is generally mounted in the center of the rear part of the roof. From the appearance of the vehicle when mounted and the appearance of the antenna device, both “shark fin antenna” and “dolphin antenna” Called (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2016-32166

  The above-described vehicle-mounted antenna device is installed at the rear part of the roof of the vehicle. In the vicinity of the rear of the vehicle-mounted antenna device, there is an insulator such as a rear window glass and a rear spoiler. When the horizontal plane gain of the in-vehicle antenna device was measured in this installed state, it was found that the antenna gain dropped at a specific azimuth angle. In the example of the horizontal plane gain of an in-vehicle antenna device that uses a V2X (Vehicle to Everything) frequency band (for example, 5 GHz or more), the azimuth angle is 0 ° for the forward direction of the vehicle and the azimuth angle is 90 ° for the right direction. When the azimuth angle is 180 ° and the left direction is azimuth angle 270 °, the horizontal gain decreases at an azimuth angle of 90 ° to 270 °, and particularly near the azimuth angle of 120 ° (110 ° to 130 °). In the vicinity of 240 ° (230 ° to 250 °), a significant decrease in horizontal plane gain was observed.

  The present invention has been devised in view of the above-described problems, and an object thereof is to provide a technique for improving the antenna gain of an in-vehicle antenna device attached to a vehicle roof.

  A first aspect of the present invention for solving the above-described problems includes an in-vehicle antenna device installed on a roof of a vehicle, and an insulation installed on the rear side of the roof that can affect the aerodynamic characteristics of the vehicle. An antenna system comprising a conductor attached to the body.

  According to the first aspect, by attaching the conductor to the insulator that is behind the vehicle-mounted antenna device installed on the roof of the vehicle and can affect the aerodynamic characteristics of the vehicle installed on the roof. The antenna gain can be improved as compared with the conventional configuration without a conductor.

  A 2nd aspect is an antenna system of a 1st aspect in which the said conductor has a shape along the shape of the said insulator.

  According to the 2nd aspect, a conductor can be made into the shape along the shape of the insulator used as an attachment destination. For example, the conductor may be configured in a tape shape and attached to an insulator.

  A 3rd aspect is an antenna system of the 1st or 2nd aspect in which the said conductor is attached to the predetermined area | region by the side of the said vehicle-mounted antenna apparatus of the said insulator.

  According to the third aspect, the effect of the first or second aspect is achieved by attaching the conductor to the predetermined area on the in-vehicle antenna device side, compared to when the conductor is not attached to the predetermined area on the in-vehicle antenna apparatus side. The effect can be exhibited more.

  A 4th aspect is an antenna system of the 3rd aspect in which the said conductor is attached so that the said predetermined area may be covered.

  According to the 4th aspect, the effect of a 1st or 2nd aspect can be exhibited more by attaching a conductor so that a predetermined area | region may be covered compared with a 3rd aspect.

  In a fifth aspect, the predetermined region is a region having a range that is three times or more of a wavelength related to a communication frequency of the in-vehicle antenna device starting from the in-vehicle antenna device. It is an antenna system of the aspect.

  Further, in the sixth aspect, the predetermined region is a region within a range of 5 times or less of a wavelength related to a communication frequency of the vehicle-mounted antenna device, starting from the vehicle-mounted antenna device. The antenna system according to any one of the fifth aspects.

  According to the fifth or sixth aspect, the size of the predetermined area can be limited.

  A seventh aspect is the antenna system according to any one of the first to sixth aspects, wherein the insulator is glass.

  According to the 7th aspect, the effect similar to the 1st-6th aspect can be acquired in the vehicle from which the back of the installed vehicle-mounted antenna apparatus becomes a rear window.

  An eighth aspect is the antenna system according to any one of the first to sixth aspects, wherein the insulator is a spoiler.

  According to the 8th aspect, the effect similar to the 1st-6th aspect can be acquired in the vehicle by which the rear spoiler is attached behind the installed vehicle-mounted antenna apparatus.

  A ninth aspect includes a roof on which an in-vehicle antenna device is installed, an insulator installed on the vehicle rear side of the roof that can affect aerodynamic characteristics of the vehicle, and the insulator on the in-vehicle antenna device side of the insulator. And a conductor attached to the predetermined area.

  According to the ninth aspect, it is possible to realize a vehicle that can obtain the same effects as those of the first aspect.

  A tenth aspect is a spoiler that is attached to a vehicle rear side of a roof on which an in-vehicle antenna device is installed, and in which a conductor is attached to a predetermined region on the in-vehicle antenna device side.

  According to the 10th aspect, the spoiler from which the effect similar to a 1st aspect is acquired is realizable.

The figure which shows the structural example of the antenna system of 1st Embodiment, the spoiler provided with the said antenna system, and the structural example of a vehicle. The schematic diagram for demonstrating the positional relationship of the element of the antenna system in 1st Embodiment. The graph which shows an example of the relationship between the distance L2 and the minimum value of a horizontal plane gain in the vicinity of a specific azimuth angle of the vehicle-mounted antenna device. The graph which shows an example of the relationship between distance L1 in the state without a conductor, and the minimum value of a horizontal plane gain in the vicinity of the specific azimuth angle of a vehicle-mounted antenna device. The graph which shows the horizontal plane gain of the vehicle-mounted antenna apparatus of 1st Embodiment. The figure which shows the modification of 1st Embodiment. The figure which shows the structural example of the antenna system of 2nd Embodiment, and the structural example of the vehicle provided with the said antenna system. The schematic diagram for demonstrating the positional relationship of the element of the antenna system of 2nd Embodiment. The graph which shows the horizontal surface gain of the vehicle-mounted antenna apparatus of 2nd Embodiment. The figure which shows the modification of the conductor based on 2nd Embodiment.

  Hereinafter, an example of an embodiment to which the present invention is applied will be described, but it is needless to say that a form to which the present invention can be applied is not limited to the following embodiment. The definition of direction in the following description is as follows. The front / rear / left / right / up / down directions are the same as the front / rear / left / right / up / down directions of the vehicle when the vehicle-mounted antenna device is mounted on the vehicle. The horizontal direction can be referred to as the horizontal direction, and the vertical direction as the vertical direction. In order to facilitate understanding of the direction, the front-rear direction and the left-right direction are indicated by line segments with arrows in the drawing. In addition, the intersection of each line segment with an arrow does not mean a coordinate origin. In the following description, the horizontal plane refers to the horizontal plane of the vehicle 10, and the horizontal plane gain refers to the vertical polarization gain of the antenna element 33 in the horizontal plane.

[First Embodiment]
FIG. 1 is a diagram showing a configuration example of an antenna system of the present embodiment, a spoiler equipped with the antenna system, and a configuration example of a vehicle, and is a perspective view looking down slightly upward from the left rear side of the vehicle.

  The vehicle 10 of the present embodiment is a hatchback type passenger vehicle, and includes a spoiler 20 at the rear end of the roof 12 that covers the front end of the glass 14 of the rear window.

  The spoiler 20 is a part that can affect the aerodynamic characteristics of the vehicle 10 by being installed on the rear side of the roof 12, and is an insulator made of a resin such as ABS (Acrylonitrile Butadiene Styrene) resin. The left and right width (the length in the left and right direction) of the spoiler 20 has the same or substantially the same level as the left and right width of the upper surface of the roof 12. Alternatively, from the viewpoint of aerodynamic performance, it may be slightly narrower than the left and right width of the upper surface of the roof 12. The front end portion of the upper surface of the spoiler 20 has a shape along the rear end of the roof 12, and is provided in the vehicle 10 so that the front end portion of the upper surface is located in the vicinity of the rear end portion of the roof 12.

The antenna system 30 includes an in-vehicle antenna device 32 installed at the rear portion of the roof 12 of the vehicle 10 and a conductor 34 attached to the spoiler 20.
An antenna element 33 is built in the vehicle-mounted antenna device 32. The antenna element 33 of the present embodiment is a DS2 (Dedicated Short Range Communications) V2X (Vehicle to Everything) communication antenna. The antenna element 33 may be a cellular V2X communication antenna. Furthermore, it may be a dipole antenna, a monopole antenna, a sleeve antenna, a collinear antenna array, or the like.

  FIG. 2 is a schematic diagram for explaining the positional relationship of each element of the antenna system 30 in the present embodiment. For ease of understanding, the steel plate of the roof 12 is expressed in a plate shape, and the vehicle body and the frame portion of the rear hatch are not shown.

  The conductor 34 of the present embodiment is an electrically conductive sheet material, and is realized by, for example, a copper or aluminum sheet material or an electrically conductive resin sheet material. A tape-shaped conductor 34 may be used. The conductor 34 is stuck along the upper surface shape of the spoiler 20. Specifically, it starts from the front end of the spoiler 20 and is attached so as to cover a predetermined area on the in-vehicle antenna device 32 side.

  In the predetermined region, the distance L2 in the vehicle front-rear direction along the roof 12 and the spoiler 20 from the antenna element 33 of the in-vehicle antenna device 32 to the rear end of the conductor 34 is the communication frequency of the antenna element 33. The wavelength is 3 times or more of the wavelength λ, preferably 3 times or more and 5 times or less.

  FIG. 3 is a graph showing an example of the relationship between the distance L2 in the present embodiment and the minimum value of the horizontal plane gain in the vicinity of the specific azimuth angle of the in-vehicle antenna device 32. The horizontal axis of the graph of FIG. 3 is the distance L2, and is indicated by a multiple of the wavelength λ related to the communication frequency of the antenna element 33. Further, the vertical axis of the graph of FIG. 3 indicates the minimum value of the horizontal plane gain. The minimum value of the horizontal plane gain near the azimuth angle of 120 ° is indicated by a broken line, and the minimum value of the horizontal plane gain near the azimuth angle of 240 ° is indicated by a solid line. The azimuth angle is defined as an azimuth angle of 0 ° in the forward direction of the vehicle 10, an azimuth angle of 90 ° in the right direction, an azimuth angle of 180 ° in the rearward direction, and an azimuth angle of 270 ° in the left direction. Further, the vicinity of azimuth angle 120 ° is a range of azimuth angles 110 ° to 130 °, and the vicinity of azimuth angle 240 ° is a range of azimuth angles 230 ° to 250 °. The vicinity of the azimuth angle of 120 ° and the azimuth angle of 240 ° will be referred to as the vicinity of the specific azimuth angle.

  As shown in FIG. 3, when the distance L2 is three times or more the wavelength λ, a significant improvement can be clearly seen by suppressing a decrease in the horizontal plane gain in the vicinity of the specific azimuth angle. In addition, when the distance L2 exceeds about 5 times the wavelength λ, the tendency to improve the horizontal plane gain near the specific azimuth angle becomes dull. On the other hand, when the vehicle-mounted antenna device 32 performs V2X communication, the wavelength λ related to the communication frequency is about 52 mm, and the distance L2 is 260 mm when the wavelength λ is 5 times. 260 mm is a length that exceeds the longitudinal length of a rear spoiler of a general passenger car, and the conductor 34 having such a long distance L2 is difficult to physically install. Therefore, the distance L2 is preferably 3 times or more of the wavelength λ, and more preferably in the range of 3 to 5 times.

  When the rear spoiler has a short front-rear length and the distance L2 cannot be secured as an attachment area of the conductor 34, the installation position of the vehicle-mounted antenna device 32 on the roof 12 is shifted to the front side of the vehicle to secure the distance L2. Can be adopted. In this case, however, the distance L1 (the distance in the vehicle longitudinal direction from the antenna element 33 to the rear end of the roof 12) occupies most of the distance L2. Therefore, the relationship between the distance L1 and the horizontal plane gain near the specific azimuth angle will be described with reference to FIG.

  FIG. 4 shows the relationship between the distance L1 in the vehicle front-rear direction from the antenna element 33 to the rear end of the roof 12 in the absence of the conductor 34, and the minimum horizontal plane gain in the vicinity of the specific azimuth angle of the in-vehicle antenna device 32. It is a graph which shows an example. The notation of the graph is the same as in FIG.

  It can be seen that the distance L1 is clearly significantly improved at 3 times or more of the wavelength λ, and that the minimum value of the horizontal plane gain almost reaches a peak when the distance L1 is larger than around 5 times. Therefore, in a case where a sufficient distance L2 cannot be secured for the spoiler 20, the installation position of the in-vehicle antenna device 32 on the roof 12 may be appropriately shifted to the vehicle front side to secure the distance L2.

  FIG. 5 is a graph showing the horizontal plane gain of the in-vehicle antenna device 32 of the present embodiment. The solid line indicates the characteristics when the conductor 34 is attached to a region where the distance L2 is 5.3 times the wavelength λ, and the broken line indicates the characteristics when the conductor 34 is not provided.

  As shown in the graph, the horizontal plane gain is higher when the conductor 34 is attached than in the configuration without the conductor 34 in the range from the azimuth angle of 120 ° to 240 °. It can be seen that the gain near the specific azimuth is greatly improved by attaching the conductor 34.

  As described above, according to the present embodiment, the insulator is behind the vehicle-mounted antenna device 32 installed on the roof 12 of the vehicle 10 and can affect the aerodynamic characteristics of the vehicle 10 installed on the roof 12. By attaching the conductor 34 to the spoiler 20, the antenna gain can be improved compared to the conventional configuration without the conductor 34.

  In the present embodiment, an example is shown in which the front end of the spoiler 20 has a shape that is exactly along the rear end of the roof 12 (see FIG. 1). In this embodiment, the spoiler 20 is installed such that the upper surface of the spoiler 20 is continuous with the upper surface of the roof 12. However, as shown in FIG. 6, in the case of the vehicle 10 in which the upper surface of the rear hatch frame 16 is positioned so as to be continuous with the upper surface of the roof 12, the spoiler 20 is disposed at the front end as shown in FIG. 6. This is a spoiler 20B having a structure in which a cutout portion 21 in which the upper end portion of the frame 16 is exposed is provided. Even in this case, since the upper end portion of the frame 16 can be identified with the roof 12, if the conductor 34 is attached to the upper surface portion excluding the notch portion 21 of the spoiler 20B, as shown in FIG. The same effect as this embodiment can be obtained.

  In the configuration of FIG. 6, at first glance, it seems that the connection between the steel plate (conductor) of the roof 12 and the conductor 34 is broken behind the in-vehicle antenna device 32, but the steel plate (conductor) of the frame 16 of the rear hatch. Thus, the steel plate (conductor) of the roof 12 and the conductor 34 are connected to each other, and a series of conductors from the roof 12 to the upper end of the frame 16 of the rear hatch to the conductor 34 can be secured. You can get it.

  Similarly, in a configuration similar to the configuration in FIG. 6, the same effect as in the present embodiment can be obtained even in a configuration in which the notch 21 is covered with a metal spoiler. Also in the configuration of FIG. 2, it is allowed to provide a gap between the rear end of the roof 12 and the front end of the conductor 34 as long as the same effect as in the present embodiment can be obtained.

[Second Embodiment]
FIG. 7 is a diagram showing the configuration of the vehicle 10B and the antenna system 30 in the second embodiment, and is a perspective view looking down from the slightly upper left side of the vehicle.
FIG. 8 is a schematic diagram for explaining the positional relationship of each element of the antenna system 30 of the present embodiment. For ease of understanding, the steel plate of the roof 12 is expressed in a plate shape, and the frame portion of the vehicle body is not shown.
In addition, in the description of the present embodiment including these figures, the same reference numerals are given to the same components as those in the first embodiment, and overlapping descriptions will be appropriately omitted.

  The vehicle 10B of the present embodiment has an outer shape called a sedan type. The glass 14 of the rear window is smoothly connected from the roof 12. The glass 14 is designed to affect the aerodynamic characteristics of the vehicle 10B. For example, the inclination angle from the horizontal plane of the roof 12 in the vicinity of the glass 14 is about 10 to 15 °, and the inclination angle of the glass 14 in the vicinity of the roof 12 is 25 ° or less.

  If the inclination angle of the glass 14 exceeds 30 ° from the horizontal plane in the vicinity of the roof 12 and the glass 14, the first implementation is to influence the aerodynamic characteristics when the vehicle 10 </ b> B is traveling. The specification which mounts the spoiler 20 behind the roof 12 like a form becomes suitable. In the vehicle 10B of this embodiment, the spoiler 20 is not attached. Therefore, in the present embodiment, the conductor 34B is attached to the upper end portion of the glass 14 of the rear window.

  Specifically, the left and right width of the conductor 34B is the same as or substantially the same as the left and right width of the glass 14 of the rear window. The front end of the conductor 34B is attached to the front end of the glass 14 of the rear window so as to be connected to the rear end of the roof 12 as much as possible. The front-rear width of the conductor 34B is set such that the distance from the antenna element 33 to the rear end of the conductor 34B is the same distance L2 as in the first embodiment.

  FIG. 9 is a graph showing the horizontal gain of the in-vehicle antenna device 32. The solid line indicates the characteristics of this embodiment when the conductor 34B is attached to a region where the distance L2 is five times the wavelength λ, and the broken line indicates the characteristics when the conductor 34 is not attached. As shown in the graph, it can be seen that the same effect as in the first embodiment can be obtained in this embodiment.

[Modification]
As mentioned above, although an example of the embodiment to which the present invention is applied has been described, the form to which the present invention can be applied is not limited to the above form, and additions, omissions, and changes of components can be appropriately made.

[Modification 1]
For example, in the first embodiment, the conductor 34 is attached to the outer surface of the spoiler 20. However, the conductor 34 may be attached before the spoiler 20 is painted in the manufacturing stage of the spoiler 20. The conductor 34 may be attached to the inner surface of the spoiler 20. In such a case, the conductor 34 is difficult to see from the outside, and the appearance of the vehicle 10 is improved.

[Modification 2]
Moreover, in the said embodiment, the structure which becomes the top view substantially rectangular shape of the conductor 34 was illustrated. Specifically, the conductor 34 and the conductor 34B have a right and left width that is adapted to the horizontal width of the spoiler 20 and the glass 14, and a front and rear width that is a square L2 from the antenna element 33 to the rear end of the conductor 34 and the conductor 34B. It illustrated as a structure which comprises the shape sheet shape. However, the shape of the conductor 34 and the conductor 34B is not limited to a substantially rectangular shape when viewed from above. For example, referring to the second embodiment as a base, as shown in FIG. 10, in the vehicle 10 </ b> C, a predetermined region having a radius L <b> 2 from the antenna element 33 is set, and the region in the glass 14 that is an insulator. An antenna system 30C in which the conductor 34C is attached may be configured. Even if it is the said structure, the effect similar to the said embodiment is acquired. In addition, the said structure is applicable similarly to the spoilers 20 and 20B of 1st Embodiment.

DESCRIPTION OF SYMBOLS 10 ... Vehicle 12 ... Roof 14 ... Glass 20 ... Spoiler 30 ... Antenna system 32 ... In-vehicle antenna device 33 ... Antenna element 34 ... Conductor L1 ... Distance L2 ... Distance

Claims (10)

An in-vehicle antenna device installed on the roof of the vehicle;
A conductor attached to an insulator installed behind the roof of the roof that may affect the aerodynamic characteristics of the vehicle;
An antenna system comprising: The conductor has a shape along the shape of the insulator;
The antenna system according to claim 1. The conductor is attached to a predetermined region on the vehicle-mounted antenna device side of the insulator,
The antenna system according to claim 1 or 2. The conductor is attached so as to cover the predetermined area.
The antenna system according to claim 3. The predetermined region is a region having a range of three times or more of a wavelength related to a communication frequency of the vehicle-mounted antenna device, starting from the vehicle-mounted antenna device.
The antenna system according to claim 3 or 4. The predetermined region is a region having a range of 5 times or less of a wavelength related to a communication frequency of the vehicle-mounted antenna device, starting from the vehicle-mounted antenna device.
The antenna system according to any one of claims 3 to 5. The insulator is glass;
The antenna system according to any one of claims 1 to 6. The insulator is a spoiler;
The antenna system according to any one of claims 1 to 6. A roof on which an in-vehicle antenna device is installed;
An insulator installed behind the roof that can affect aerodynamic characteristics of the vehicle;
A conductor attached to a predetermined region of the insulator on the vehicle antenna device side;
Vehicle equipped with. A spoiler that is attached to the vehicle rear side of a roof on which an in-vehicle antenna device is installed,
A spoiler in which a conductor is attached to a predetermined region on the vehicle-mounted antenna device side.

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