Antenna device and vehicle

Abstract

To improve a gain of a low elevation angle of an antenna device.SOLUTION: An antenna device is partially arranged in a recessed part where a wall rising up from a bottom surface is formed and has an antenna which responds to a predetermined frequency band. The antenna is located in a position distant from an upper end of the wall inclined to a direction which forms an obtuse angle to the bottom surface.SELECTED DRAWING: Figure 4A

Description

[Technical field]

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

[0002] In recent years, various antenna devices mounted on vehicles have been developed. For example, the antenna device described in Patent Document 1 is disposed inside a recess formed on the interior side of the roof of the vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 7,847,744 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, as described in Patent Document 1, when an antenna device is placed inside a recess formed on the interior side of the roof of a vehicle, the gain of the antenna device at low elevation angles may become relatively low due to the effects of reflection and blocking of radio waves by the inner walls of the recess.

[0005] One object of the present invention is to improve the low elevation angle gain of an antenna device. Other objects of the present invention will become apparent from the description herein. [Means for solving the problem]

[0006] One aspect of the present invention is an antenna device, a portion of which is positioned within a recess having a wall rising from a bottom surface, the antenna device comprising an antenna corresponding to a predetermined frequency band, the antenna being positioned away from an upper end of the wall, which is inclined in a direction such that the angle it forms with the bottom surface is an obtuse angle.

[0007] One aspect of the present invention is an antenna device, a portion of which is placed within a recess having a wall rising from a bottom surface, the antenna device having an antenna corresponding to a predetermined frequency band, the antenna being positioned at a distance from the wall of the recess, which is circular in top view, that is an odd multiple of a quarter wavelength of the predetermined frequency band.

[0008] One aspect of the present invention is a vehicle having a bottom surface and a wall rising from the bottom surface, with a recess in the bottom surface for placing an antenna corresponding to a predetermined frequency band, wherein the wall is inclined in a direction such that the angle it forms with the bottom surface is an obtuse angle.

[0009] One aspect of the present invention is a vehicle having a bottom surface and a wall rising from the bottom surface, with a recess that is circular in top view, wherein the recess enables an antenna corresponding to a predetermined frequency band to be positioned at a distance from the wall that is an odd multiple of a quarter wavelength of the predetermined frequency band.

[0010] According to the above-described aspects of the present invention, the gain of the antenna device at low elevation angles can be improved. [Brief description of the drawings]

[0011] [Figure 1] 1 is a top view of an antenna device according to a first embodiment. [Diagram 2] FIG. 2 is an exploded perspective view of the base, case, AM antenna, FM antenna, and DAB antenna according to the first embodiment. [Diagram 3] FIG. 1 is a diagram showing an example of a DAB antenna having an inverted L antenna structure. [Figure 4A] FIG. 2 is a perspective view of a recess in which a V2X antenna is disposed according to an example of the first embodiment. [Figure 4B] FIG. 2 is a cross-sectional view of a recess in accordance with an example of the first embodiment in which a V2X antenna is disposed. [Diagram 5] 13 is a graph showing the directivity pattern of the V2X antenna when the angle between the bottom surface of the recess and the inclined portion is 90°. [Figure 6] 13 is a graph showing the directivity pattern of the V2X antenna when the angle between the bottom surface of the recess and the inclined portion is 120°. [Figure 7] 13 is a graph showing the directivity pattern of the V2X antenna when the angle between the bottom surface of the recess and the inclined portion is 130°. [Figure 8] 13 is a graph showing the directivity pattern of the V2X antenna when the angle between the bottom surface of the recess and the inclined portion is 135°. [Figure 9] FIG. 11 is a cross-sectional view of a recess according to another example of the first embodiment in which a V2X antenna is arranged. [Figure 10] FIG. 11 is a cross-sectional view of a recess according to still another example of the first embodiment in which a V2X antenna is arranged. [Figure 11A] FIG. 13 is a perspective view of a recess in accordance with an example of a second embodiment in which a V2X antenna is disposed. [Figure 11B] FIG. 11 is a cross-sectional view of a recess in accordance with an example of a second embodiment in which a V2X antenna is disposed. [Figure 12] 1 is a graph showing the relationship between the depth of the recess and the average gain in the horizontal plane of the V2X antenna. [Figure 13] FIG. 11 is a perspective view of a V2X antenna according to another example of the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In all the drawings, the same components are given the same reference numerals, and the description will be omitted as appropriate.

[0013] In this specification, ordinal numbers such as "first," "second," "third," etc., unless otherwise specified, are used merely to distinguish between similarly named configurations and do not imply any particular characteristics (e.g., order or importance) of the configurations.

[0014] ==First embodiment== FIG. 1 is a top view of an antenna device 10 according to the first embodiment.

[0015] In Fig. 1 and the following figures, an arrow showing the first direction X, the second direction Y, or the third direction Z indicates that the direction from the base end of the arrow to the tip is the positive direction of the direction shown by the arrow, and the direction from the tip of the arrow to the base end is the negative direction of the direction shown by the arrow. In Fig. 1 and the following figures, a white circle with a black dot showing the first direction X, the second direction Y, or the third direction Z indicates that the direction from the back of the paper to the front is the positive direction of the direction shown by the white circle with a black dot, and the direction from the front of the paper to the back is the negative direction of the direction shown by the white circle with a black dot. In Fig. 1 and the following figures, a white circle with an X showing the first direction X, the second direction Y, or the third direction Z indicates that the direction from the front of the paper to the back is the positive direction of the direction shown by the white circle with an X, and the direction from the back of the paper to the front is the negative direction of the direction shown by the white circle with an X.

[0016] In FIG. 1, a recess 4 is formed in a roof 2, which is a conductor of a vehicle (not shown) on which an antenna device 10 is mounted. The first direction X is the front-rear direction as viewed from the recess 4 or the driver's seat of the vehicle. The positive direction of the first direction X is the direction from rear to front as viewed from the recess 4 or the driver's seat of the vehicle. The negative direction of the first direction X is the direction from front to rear as viewed from the recess 4 or the driver's seat of the vehicle. The second direction Y is perpendicular to the first direction X. The second direction Y is the left-right direction as viewed from the recess 4 or the driver's seat of the vehicle. The positive direction of the second direction Y is the direction from right to left as viewed from the recess 4 or the driver's seat of the vehicle. The negative direction of the recess 4 is the direction from left to right as viewed from the driver's seat of the vehicle. The third direction Z is perpendicular to both the first direction X and the second direction Y. The third direction Z is the up-down direction as viewed from the recess 4 or the driver's seat of the vehicle. The positive direction of the third direction Z is the direction from bottom to top as viewed from the recess 4 or the driver's seat of the vehicle. The negative direction of the third direction Z is a direction from above to below when viewed from the recess 4 or the driver's seat of the vehicle. The same applies to the figures subsequent to FIG.

[0017] Hereinafter, where necessary, a direction perpendicular to the third direction Z will be referred to as the XY plane direction. Hereinafter, where necessary, a plane perpendicular to the vertical direction will be referred to as the horizontal plane. The third direction Z of the recess 4 may be inclined with respect to the vertical direction. For example, if the recess 4 is formed on the rear side of the roof of the vehicle, the rear side is not parallel to the horizontal plane. In other words, since the surface of the recess 4 on which the antenna is placed is not parallel to the horizontal plane, the third direction Z of the recess 4 may be deviated from the vertical direction (inclined with respect to the vertical direction).

[0018] The antenna device 10 includes a base 110, an AM (Amplitude Modulation) antenna 200, an FM (Frequency Modulation) antenna 300, a DAB (Digital Audio Broadcasting) antenna 400, a ground element 500, a V2X (Vehicle to Everything) antenna 600, and a GNSS (Global Navigation Satellite System) antenna 700. The antenna device 10 may include a communication antenna such as a TEL (Telephone) antenna or a Wi-Fi (registered trademark) antenna instead of or in addition to the V2X antenna 600. The AM antenna 200 includes an AM capacitance loading element 210. The FM antenna 300 includes an FM capacitance loading element 310. The DAB antenna 400 includes a DAB capacitance loading element 410.

[0019] The base 110, the AM antenna 200, the FM antenna 300, the DAB antenna 400, the ground element 500, the V2X antenna 600, and the GNSS antenna 700 are disposed inside the recess 4. The recess 4 is formed on the upper surface of the roof 2 of the vehicle on which the antenna device 10 is mounted, on the positive side in the third direction Z. The recess 4 is formed across the roof 2 of the vehicle in the second direction Y (the width direction of the vehicle). The recess 4 is formed on the roof 2 on the rear side (the negative side in the first direction X) as viewed from the driver's seat of the vehicle in the first direction X. The upper part of the recess 4 is covered, for example, by a resin roof that is a non-conductor (not shown). As viewed from the third direction Z, the length of the recess 4 in the second direction Y is longer than the length of the recess 4 in the first direction X. However, the shape of the recess 4 is not limited to this example. The target on which each antenna is mounted is not limited to a vehicle. That is, each antenna may be disposed inside a recess formed in a conductor different from the roof 2 of the vehicle.

[0020] Here, the antenna device 10 is not limited to being attached to a vehicle, but may be brought into the vehicle and used within the vehicle. In addition, the antenna device 10 of the present embodiment is used in a "vehicle" that is a vehicle with wheels, but is not limited thereto, and may be used in a moving object such as an aircraft such as a drone, a probe, a construction machine without wheels, an agricultural machine, or a ship. Furthermore, the antenna device 10 may be an antenna device used for objects other than moving objects.

[0021] In this embodiment, since each antenna is disposed inside the recess 4, each antenna is not visible from the outside of the vehicle. Therefore, compared to the case where each antenna is disposed above the positive side of the third direction Z of the roof 2, the constraints on the design of the vehicle are reduced, and the degree of freedom in the design of the vehicle is improved. Also, compared to the case where each antenna is disposed above the positive side of the third direction Z of the roof 2, the influence of aerodynamics by each antenna can be suppressed. Furthermore, in this embodiment, each antenna can be made less susceptible to noise from the vehicle compared to the case where each antenna is disposed other than on the roof 2 (specifically, the recess 4 formed in the roof 2). However, each antenna may be built into an exterior part such as a spoiler. In that case, each antenna may be configured to block noise that is influenced by the vehicle.

[0022] The AM antenna 200, the FM antenna 300, and the DAB antenna 400 are disposed on the upper surface side of the base 110 in the positive direction of the third direction Z. As viewed from the third direction Z, the base 110 has a substantially rectangular shape having a pair of short sides substantially parallel to the first direction X and a pair of long sides substantially parallel to the second direction Y. However, the shape of the base 110 is not limited to this example. As viewed from the third direction Z, the base 110, the AM antenna 200, the FM antenna 300, and the DAB antenna 400 are disposed on the negative side of the second direction Y with respect to the center of the second direction Y of the recess 4. As viewed from the third direction Z, the AM antenna 200, the FM antenna 300, and the DAB antenna 400 are arranged substantially parallel to the second direction Y. Specifically, as viewed from the third direction Z, the FM antenna 300 is disposed between the AM antenna 200 and the DAB antenna 400 in the second direction Y. As viewed from the third direction Z, the AM antenna 200 is disposed to the right of the FM antenna 300 in the negative direction of the second direction Y. When viewed from the third direction Z, the DAB antenna 400 is disposed to the left of the FM antenna 300 in the positive direction of the second direction Y. However, the arrangement of the AM antenna 200, the FM antenna 300 and the DAB antenna 400 is not limited to this example. The AM antenna 200 shown in Fig. 1 is disposed at a position close to the end of the roof 2 of the vehicle on the negative side in the second direction Y.

[0023] When viewed from the third direction Z, the AM capacitance loading element 210 has a substantially rectangular shape having a pair of long sides substantially parallel to the first direction X and a pair of short sides substantially parallel to the second direction Y. However, the shape of the AM capacitance loading element 210 is not limited to this example. The AM capacitance loading element 210 can have various shapes such as a strip, a circle, a polygon, a three-dimensional structure, a meander, etc. The AM capacitance loading element 210 may have a shape that reduces interference with other antennas arranged in the vicinity of the AM capacitance loading element 210. For example, the AM capacitance loading element 210 may have a slot, a slit, or an opening. Alternatively, the AM capacitance loading element 210 may extend in a meander shape. The AM capacitance loading element 210 may have a structure that controls the gain or directivity of other antennas arranged in the vicinity of the AM capacitance loading element 210. For example, the AM capacitance loading element 210 may operate as a reflector or director for other antennas.

[0024] When viewed from the third direction Z, the FM capacitance loading element 310 has a substantially rectangular shape having a pair of short sides substantially parallel to the first direction X and a pair of long sides substantially parallel to the second direction Y. However, the shape of the FM capacitance loading element 310 is not limited to this example. As with the description of the shape of the AM capacitance loading element 210, the FM capacitance loading element 310 can also adopt various shapes.

[0025] When viewed from the third direction Z, the DAB capacitance loading element 410 has a substantially rectangular shape having a pair of short sides substantially parallel to the first direction X and a pair of long sides substantially parallel to the second direction Y. However, the shape of the DAB capacitance loading element 410 is not limited to this example. As with the description of the shape of the AM capacitance loading element 210, the DAB capacitance loading element 410 can also adopt various shapes.

[0026] When viewed from the third direction Z, a right side of the FM capacitance loading element 310 in the negative direction of the second direction Y and a left side of the AM capacitance loading element 210 in the positive direction of the second direction Y face each other in the second direction Y. When viewed from the third direction Z, a positive side of the FM capacitance loading element 310 in the second direction Y and a negative side of the DAB capacitance loading element 410 in the second direction Y face each other in the second direction Y.

[0027] The antenna device 10 may include a Sirius XM antenna (hereinafter, referred to as an SXM antenna) instead of the DAB antenna 400. The DAB antenna 400 is an antenna capable of receiving radio waves in the European area, and the SXM antenna is an antenna capable of receiving satellite radio waves in the US area. For this reason, generally, both of these antennas are not mounted on the same vehicle. Therefore, the space for arranging the DAB antenna 400 and the space for arranging the SXM antenna may be the same. In this case, the antenna device 10 can be made smaller than when the space for arranging the DAB antenna 400 and the space for arranging the SXM antenna are formed separately.

[0028] When viewed from the third direction Z, the ground element 500, the V2X antenna 600, and the GNSS antenna 700 are disposed substantially in the center of the recess 4 in the second direction Y. The V2X antenna 600 and the GNSS antenna 700 are disposed on the upper surface side of the ground element 500 in the positive direction of the third direction Z. When viewed from the third direction Z, the V2X antenna 600 and the GNSS antenna 700 are arranged substantially parallel to the first direction X. Specifically, when viewed from the third direction Z, the V2X antenna 600 is disposed on the negative side of the GNSS antenna 700 in the first direction X. When viewed from the third direction Z, the GNSS antenna 700 is disposed on the positive side of the V2X antenna 600 in the first direction X. However, the arrangement of the V2X antenna 600 and the GNSS antenna 700 is not limited to this example.

[0029] As viewed from the third direction Z, it is preferable that the communication antennas for transmitting and receiving radio waves, such as the V2X antenna 600 and the TEL antenna, are not disposed between the three receiving antennas for receiving radio waves, such as the AM antenna 200, the FM antenna 300, and the DAB antenna 400. This is to suppress interference of the communication antennas with the receiving antennas. In the embodiment, the V2X antenna 600 is disposed on the negative side of the second direction Y relative to any of the AM antenna 200, the FM antenna 300, and the DAB antenna 400. Therefore, isolation between the V2X antenna 600 and each of the AM antenna 200, the FM antenna 300, and the DAB antenna 400 can be ensured. Note that the V2X antenna 600 improves the gain in the front-rear direction to give directivity to the vehicle (first direction X). In other words, the gain is improved (strengthened) in a direction that does not affect the radio wave reception sensitivity of the AM antenna 200, the FM antenna 300, and the DAB antenna 400, so that they can be disposed so as not to interfere with each other.

[0030] An inclined portion 4a is formed on a part of the inner side of the recess 4. Specifically, the inclined portion 4a is formed on both sides of the ground element 500, the V2X antenna 600, and the GNSS antenna 700 in the first direction X. The inclined portion 4a is a portion rising from the bottom surface of the recess 4. The inclined portion 4a is inclined at an angle of 45° or the like from the bottom surface of the recess 4 on the negative side of the third direction Z toward the upper end opening on the positive side of the third direction Z. In other words, the inclined portion 4a is inclined in a direction in which the angle formed with the bottom surface of the recess 4 is a predetermined angle. However, the predetermined angle of the inclined portion 4a and the arrangement in the recess 4 are not limited to the above-mentioned aspect. In this embodiment, the inner side of the recess 4 and the inclined portion 4a are walls formed of a conductor, and in the following description, the "inclined portion" is called a "conductor wall" or may be simply called a "wall". The details of the inclined portion in the recess 4 will be described later.

[0031] FIG. 2 is an exploded perspective view of the base 110, the case 120, the AM antenna 200, the FM antenna 300, and the DAB antenna 400 according to the first embodiment.

[0032] The base 110 can be electrically connected to a metal portion of the roof 2 shown in FIG. 1. For example, the base 110 may be directly connected to the roof 2. Alternatively, the base 110 may be electrically connected to the roof 2 via another conductor such as a conductive plate or a conductive sheet. When the base 110 is directly connected to the roof 2, conductor loss can be reduced and ground performance can be improved compared to when the base 110 is electrically connected to the roof 2 via another conductor.

[0033] The base 110 may be electrically connected to the roof 2 via a filter member. Examples of the filter member include a filter circuit, a filter pattern, an electronic component having a filtering function, and a combination thereof. By disposing the filter member, it is possible to ensure isolation between an antenna mounted on the base 110 and an antenna disposed outside the base 110. Therefore, it is possible to suppress interference between these antennas. In addition, it is possible to prevent noise from entering the antenna mounted on the base 110.

[0034] The base 110 may be electrically connected to the roof 2 by capacitive coupling. For example, for an antenna that supports a relatively high frequency band, even if the base 110 is electrically connected to the roof 2 by capacitive coupling, the roof 2 and the base 110 can operate as ground. When the base 110 is electrically connected to the roof 2 by capacitive coupling, the base 110 can be connected to the roof 2 by, for example, a technique for joining resin or non-ferrous metal, without connecting the base 110 to the roof 2 by welding. Therefore, the base 110 can be connected to the roof 2 at a lower cost than when the base 110 is connected to the roof 2 by welding.

[0035] The AM amplifier board 230, the FM amplifier board 330, and the DAB amplifier board 430 are arranged on the upper surface side of the base 110 in the positive direction of the third direction Z. The AM capacitance loading element 210 is arranged at a position above the positive side of the third direction Z from the upper surface of the AM amplifier board 230 on the positive side of the third direction Z. The FM capacitance loading element 310 is arranged at a position above the positive side of the third direction Z from the upper surface of the FM amplifier board 330 on the positive side of the third direction Z. The DAB capacitance loading element 410 is arranged at a position above the positive side of the third direction Z from the upper surface of the DAB amplifier board 430 on the positive side of the third direction Z.

[0036] The case 120 is formed of a radio wave-transmitting resin or the like, and has a substantially rectangular parallelepiped shape. However, the shape of the case 120 is not limited to this example. The case 120 covers the base 110, the AM antenna 200, the FM antenna 300, and the DAB antenna 400 from above on the positive side of the third direction Z. The case 120 forms a predetermined storage space together with the base 110. The AM antenna 200, the FM antenna 300, and the DAB antenna 400 are stored inside the storage space. The case 120 may be mounted on the base 110 via an elastic surrounding body such as an O-ring or a pad. By mounting the elastic surrounding body, the storage space can be made waterproof or dustproof.

[0037] Considering the influence of water generation such as condensation on roof 2, case 120 may be shaped to have a relatively large storage space volume. The outer surface of case 120 may be formed with a protrusion that guides water adhering to the outer surface of case 120 downward in the negative direction of third direction Z. When such a protrusion is formed, even if water adheres to the outer surface of case 120 due to factors such as condensation on roof 2, the water can be prevented from adhering to AM antenna 200, FM antenna 300, and DAB antenna 400.

[0038] The AM antenna 200, the FM antenna 300, and the DAB antenna 400 according to this embodiment are disposed inside the recess 4 shown in FIG. 1. Therefore, each antenna is lower in the third direction Z than when each antenna is disposed in the space above the roof 2 on the positive side of the third direction Z. The lowering of the height of each antenna may reduce the radiation resistance of each antenna, which may reduce the gain of each antenna. In contrast, in this embodiment, the size of each of the AM capacitance loading element 210, the FM capacitance loading element 310, and the DAB capacitance loading element 410 in the XY plane direction is increased compared to when each antenna is disposed in the space above the roof 2 on the positive side of the third direction Z, thereby improving the gain, bandwidth, and antenna efficiency of each of the AM antenna 200, the FM antenna 300, and the DAB antenna 400.

[0039] It is preferable that the height in the third direction Z of each of the AM antenna 200, the FM antenna 300, and the DAB antenna 400 is as high as possible with respect to the depth in the third direction Z of the recess 4. For example, the height in the third direction Z of each of the AM antenna 200, the FM antenna 300, and the DAB antenna 400 may be 80% or more and 90% or less of the depth in the third direction Z of the recess 4. In one example, when the depth in the third direction Z of the recess 4 is 35 mm, the height in the third direction Z of each of the AM antenna 200, the FM antenna 300, and the DAB antenna 400 may be 30 mm. The AM antenna 200, the FM antenna 300, and the DAB antenna 400 are arranged below a roof such as a resin roof arranged above each antenna. By arranging each antenna along the inner surface of the roof 2, the height in the third direction Z of each antenna can be increased. By increasing the height in the third direction Z of each antenna, the gain of each antenna can be improved.

[0040] Fig. 3 is a diagram showing an example of an inverted-L antenna structure of DAB antenna 400. The matters described with reference to Fig. 3 regarding the inverted-L antenna structure of DAB antenna 400 are similarly applicable to AM antenna 200 and FM antenna 300. Note that AM antenna 200 does not have to have a coil equivalent to DAB coil 420 described later as an antenna method that does not resonate.

[0041] The DAB antenna 400 includes a DAB capacitance loading element 410 and a DAB coil 420. The DAB coil 420 is wound around a DAB bobbin 422. The lower end of the DAB coil 420 on the negative side in the third direction Z is electrically connected to a DAB power supply unit 440 arranged on a DAB amplifier board 430. The upper end of the DAB coil 420 on the positive side in the third direction is electrically connected to the end of the DAB capacitance loading element 410 on the positive side in the first direction X.

[0042] Fig. 4A is a perspective view of a recess 4D1 according to an example of the first embodiment in which a V2X antenna 600D1 is arranged. Fig. 4B is a cross-sectional view of the recess 4D1 according to an example of the first embodiment in which a V2X antenna 600D1 is arranged.

[0043] In the following description of the present embodiment, for simplicity, an antenna device in which only the V2X antenna 600D1 is arranged in a recess 4D1 formed in a roof 2A1 (see FIG. 4B) of a vehicle will be described as a model.

[0044] The V2X antenna 600D1 is, for example, a collinear antenna, and the length of the element (here, the length of the V2X antenna 600D1 in the third direction Z) corresponds to approximately one wavelength at a frequency of 5860 MHz. As shown in FIG. 4A and FIG. 4B, the V2X antenna 600D1 extends approximately parallel to the third direction Z. The V2X antenna 600D1 is disposed on the upper surface side of the support plate 610D1 in the positive direction of the third direction Z. The support plate 610D1 is disposed at a position above and away from the bottom surface of the recess 4D1 on the negative side of the third direction Z in the positive direction of the third direction Z. Therefore, the V2X antenna 600D1 is disposed at a position above and away from the bottom surface of the recess 4D1 on the negative side of the third direction Z in the positive direction of the third direction Z. In this case, the V2X antenna 600D1 can be moved closer to the upper end opening on the positive side of the third direction Z of the recess 4D1, compared to when the V2X antenna 600D1 is positioned on the bottom surface on the negative side of the third direction Z of the recess 4D1.

[0045] Although not shown, the power supply unit of the V2X antenna 600D1 is located at a side end of the support plate 610D1. The V2X antenna 600D1 transmits and receives radio waves by being fed with power from a coaxial cable (not shown) via a circuit board (not shown) electrically connected to the power supply unit. As described above, the V2X antenna 600 of this embodiment configures the antenna device 10 together with other antennas (AM antenna 200, FM antenna 300, DAB antenna 400, and GNSS antenna 700). However, the antenna device 10 may be configured with the V2X antenna 600D1 (similar to the V2X antenna 600D2 and V2X antenna 600D3 described later) as the V2X antenna 600, the support plate 610D1 (similar to the support plate 610D2 shown in FIG. 9 and the support plate 610D3 shown in FIG. 10), the power supply unit, the circuit board, and the coaxial cable. That is, the antenna device 10 may be an antenna device that does not have other antennas as an antenna and has only the V2X antenna 600. In addition, in the first embodiment, the V2X antenna 600D1 is described as an example of an antenna, but the present invention is not limited to this and can be applied to a TEL antenna, a Wi-Fi antenna, or the like.

[0046] When viewed from the third direction Z, the upper end opening of the recess 4D1 on the positive side in the third direction Z is substantially rectangular with a pair of short sides substantially parallel to the first direction X and a pair of long sides substantially parallel to the second direction Y. An inclined portion 4aD1 is formed on the front inner wall of the recess 4D1 on the positive side in the first direction X. An inclined portion 4aD2 is formed on the rear inner wall of the recess 4D1 on the negative side in the first direction X. An inclined portion 4aD3 is formed on the left inner wall of the recess 4D1 on the positive side in the second direction Y. An inclined portion 4aD4 is formed on the right inner wall of the recess 4D1 on the negative side in the second direction Y.

[0047] That is, in this embodiment, the inclined portion 4aD1, the inclined portion 4aD2, the inclined portion 4aD3, and the inclined portion 4aD4 surround the V2X antenna 600D1 in a substantially quadrilateral shape having a substantially rectangular shape. That is, when viewed from the third direction Z, the upper end opening of the recess 4D1 on the positive side in the third direction Z is surrounded by a substantially quadrilateral shape having a substantially rectangular shape. However, when viewed from the third direction Z, the upper end opening of the recess 4D1 on the positive side in the third direction Z is a substantially quadrilateral shape other than a substantially rectangular shape, so that the inclined portion 4aD1, the inclined portion 4aD2, the inclined portion 4aD3, and the inclined portion 4aD4 may surround the V2X antenna 600D1 in a substantially quadrilateral shape other than a substantially rectangular shape. Furthermore, the inclined portion may surround the V2X antenna 600D1 in a shape other than a substantially quadrilateral shape, and may not surround the V2X antenna 600D1. The inner side surface of the recess 4D1 and the inclined portions 4aD1, 4aD2, 4aD3, and 4aD4 are walls formed of a conductor.

[0048] In this embodiment, each of the inclined portions 4aD1, 4aD2, 4aD3, and 4aD4 is inclined with respect to the bottom surface of the recess 4D1 on the negative side in the third direction Z. The inclined portions 4aD1 and 4aD2 increase the width of the recess 4D1 in the first direction X from the bottom surface of the recess 4D1 on the negative side in the third direction Z toward the upper end opening on the positive side in the third direction Z. The inclined portions 4aD3 and 4aD4 increase the width of the recess 4D1 in the second direction Y from the bottom surface of the recess 4D1 on the negative side in the third direction Z toward the upper end opening on the positive side in the third direction Z.

[0049] Here, as shown in FIG. 4B, the angle between the bottom surface of the recess 4D1 and the inclined portion 4aD1 is θ1, and the angle between the bottom surface of the recess 4D1 and the inclined portion 4aD2 is θ2. In this embodiment, the angle θ1 between the bottom surface of the recess 4D1 and the inclined portion 4aD1 is equal to the angle θ2 between the bottom surface of the recess 4D1 and the inclined portion 4aD2, and both are obtuse angles (θ1=θ2>90°). In addition, although not shown in FIG. 4B, the angle θ3 between the bottom surface of the recess 4D1 and the inclined portion 4aD3 and the angle θ4 between the bottom surface of the recess 4D1 and the inclined portion 4aD4 are also equal to θ1 and θ2, and both are obtuse angles (θ1=θ2=θ3=θ4>90°). However, at least one of the angles θ1, θ2, θ3, and θ4 may be different from the other angles, or at least one of the angles θ1, θ2, θ3, and θ4 may be other than an obtuse angle. The V2X antenna 600D1 shown in FIG. 4B is disposed at a position where the distance from the inclined portion 4aD1 is approximately equal to the distance from the inclined portion 4aD2. However, the V2X antenna 600D1 may be disposed closer to the inclined portion 4aD1 or the inclined portion 4aD2. In that case, the V2X antenna 600D1 is located closer to the upper end of either the inclined portion 4aD1 or the inclined portion 4aD2.

[0050] Fig. 5 is a graph showing the directivity pattern of the V2X antenna 600D1 when the angle between the bottom surface of the recess 4D1 and the inclined portion is 90°. Fig. 6 is a graph showing the directivity pattern of the V2X antenna 600D1 when the angle between the bottom surface of the recess 4D1 and the inclined portion is 120°. Fig. 7 is a graph showing the directivity pattern of the V2X antenna 600D1 when the angle between the bottom surface of the recess 4D1 and the inclined portion is 130°. Fig. 8 is a graph showing the directivity pattern of the V2X antenna 600D1 when the angle between the bottom surface of the recess 4D1 and the inclined portion is 135°.

[0051] The graphs shown in Figures 5, 6, 7, and 8 show the directivity pattern of the V2X antenna 600D1 when the angles formed between the bottom surface of the recess 4D1 and the inclined portions 4aD1, 4aD2, 4aD3, and 4aD4 are all equal (θ1=θ2=θ3=θ4). The graphs shown in Figures 5, 6, 7, and 8 show the directivity pattern of the V2X antenna 600D1 at angles of 80°, 85°, 90°, 95°, and 100° from the zenith, i.e., low elevation angles.

[0052] The numbers around the graphs shown in Figures 5, 6, 7 and 8 indicate the azimuth (unit: °) in the horizontal plane. The numbers from the center of the graphs in Figures 5, 6, 7 and 8 to the azimuth 0° indicate the gain (unit: dBi). In the graphs shown in Figures 5, 6, 7 and 8, the azimuth 0° is the direction ahead of the vehicle. The azimuth 90° is the direction to the right of the vehicle. The azimuth 180° is the direction behind the vehicle. The azimuth 270° is the direction to the left of the vehicle.

[0053] The lengths of the upper end opening of the recess 4D1 in the first direction X and the second direction Y, the depth of the recess 4D1 in the third direction Z, the height of the V2X antenna 600D1 in the third direction Z, and the position of the positive side of the third direction Z where the support plate 610D1 is arranged are common to each V2X antenna 600D1 showing the directivity patterns of Figures 5, 6, 7, and 8. That is, the length of the upper end opening of the recess 4D1 on the positive side of the third direction Z in the first direction X is 220 mm. The length of the upper end opening of the recess 4D1 on the positive side of the third direction Z in the second direction Y is 920 mm. The depth of the recess 4D1 in the third direction Z is 35 mm. The height of the V2X antenna 600D1 in the third direction Z is 50 mm (the total height is approximately one wavelength of a frequency of 5860 MHz). The support plate 610D1 is disposed at a position 10 mm above the positive side in the third direction Z from the bottom surface on the negative side in the third direction Z of the recess 4D1.

[0054] Regarding each V2X antenna 600D1 showing the directivity patterns of Fig. 5, Fig. 6, Fig. 7, and Fig. 8, the length in the first direction X and the second direction Y of the top end opening on the positive side of the third direction Z of the recess 4D1 are maintained, while the length in the first direction X and the second direction Y of the bottom surface on the negative side of the third direction Z of the recess 4D1 are shortened in the order of Fig. 5 to Fig. 8. For example, in the V2X antenna 600D1 showing the directivity pattern of Fig. 8, the length in the first direction X of the bottom surface on the negative side of the third direction Z of the recess 4D1 is 150 mm. The length in the second direction Y of the bottom surface on the negative side of the third direction Z of the recess 4D1 is 850 mm.

[0055] As shown in Figures 5, 6, 7 and 8, the larger the angle between the bottom surface of the recess 4D1 and the inclined portion, the shallower the null of the directivity pattern. Therefore, in order to make the null of the directivity pattern shallower, the angle between the bottom surface of the recess 4D1 and the inclined portion can be made larger than 90° (i.e., an obtuse angle), for example. This can improve the gain of the antenna device 10 at low elevation angles.

[0056] In this embodiment, as shown in FIG. 4B described above, the inner side walls on both sides of the recess 4D1 in the first direction X are inclined obliquely with respect to the first direction X. Specifically, the width of the recess 4D1 in the first direction X increases from the bottom surface of the recess 4D1 on the negative side of the third direction Z toward the upper end opening on the positive side of the third direction Z. In this case, compared to the case where the inner side walls on both sides of the recess 4D1 in the first direction X are perpendicular to the first direction X, the size in the XY plane direction of the bottom surface of the recess 4D1 on the negative side of the third direction Z can be reduced while maintaining the size in the XY plane direction of the upper end opening on the positive side of the third direction Z of the recess 4D1. Therefore, compared to the case where the inner side walls on both sides of the recess 4D1 in the first direction X are perpendicular to the first direction X, it is possible to suppress the narrowing of the interior of the vehicle caused by the recess 4D1. Even if the size in the XY plane direction of the bottom surface of the recess 4D1 on the negative side in the third direction Z is reduced, the distance between the antenna voltage point of the upper end portion on the positive side in the third direction Z of each antenna, such as a capacitive loading element, and the end portion on the positive side in the third direction Z of the inner side walls on both sides in the first direction X of the recess 4D1 can be ensured. Furthermore, the recess 4D1 can be formed easily and at low cost compared to the case where the inner side walls on both sides in the first direction X of the recess 4D1 are perpendicular to the first direction X.

[0057] 4A and 4B, the inclined portions on both sides of the recess 4D1 in the first direction X are inclined with respect to the first direction X. However, only one of the inclined portions on both sides of the recess 4D1 in the first direction X may be inclined with respect to the first direction X. Also, at least one of the inclined portions on both sides of the recess 4D1 in the second direction Y may be inclined with respect to the second direction Y. That is, the antenna device 10 may have a portion where the V2X antenna is not surrounded by inclined portions.

[0058] 4A and 4B, an inclined portion inclined from the bottom surface of the recess 4D1 on the negative side in the third direction Z is described. However, this is not limited thereto, and the inner wall of the recess 4D1 may extend perpendicularly to the bottom surface from the bottom surface of the recess 4D1 to a certain height on the positive side in the third direction Z and may be further inclined. In other words, the inner wall of the recess 4D1 may have both a wall that rises perpendicularly to the bottom surface of the recess 4D1 and an inclined portion that is inclined.

[0059] An upper end opening on the positive side of the third direction Z of the inner wall of the recess 4D1 surrounding the V2X antenna is farther from the V2X antenna than a lower end on the negative side of the inner wall of the recess 4D1 in the third direction Z. In other words, the V2X antenna is disposed at a position farther from the upper end of the inclined portion of the recess 4D1 than from the lower end of the inclined portion of the recess 4D1. Furthermore, at least a part of the recess 4D1 does not face the V2X antenna. This results in significantly better directivity, particularly for a V2X antenna that produces horizontally polarized waves.

[0060] 9 is a cross-sectional view of a recess 4D2 according to another example of the first embodiment in which a V2X antenna 600D2 is arranged. The description of the V2X antenna 600D2 is the same as that of the V2X antenna 600D1 described above.

[0061] 9, the recess 4D2 extends to the rear end on the negative side of the first direction X of the vehicle. The inclined portion 4bD1 on the positive side of the first direction X of the recess 4D2 is inclined with respect to the first direction X. In this example as well, the gain of the antenna device 10 at low elevation angles can be improved.

[0062] 10 is a cross-sectional view of a recess 4D3 according to yet another example of the first embodiment in which a V2X antenna 600D3 is disposed. The description of the V2X antenna 600D3 is the same as that of the V2X antenna 600D1 described above.

[0063] In the example shown in FIG. 10, the V2X antenna 600D3 is located closer to the inclined portion 4cD1 than to the inclined portion 4cD2 (X1 < X2 shown in FIG. 10). Here, also in the example shown in FIG. 10, the upper ends of the inclined portions including the inclined portion 4cD1 and the inclined portion 4cD2 surround the V2X antenna 600D3 in a substantially rectangular shape with a substantially quadrilateral shape. The inclined portion 4cD1 is an inclined portion whose upper end is located on the first side of the substantially rectangle, and the inclined portion 4cD2 is an inclined portion that faces the first side and whose upper end is located on the second side of the substantially rectangle. Also, the first angle θ1 formed by the bottom surface of the concave portion 4D3 and the inclined portion 4cD1 is larger than the second angle θ2 formed by the bottom surface of the concave portion 4D3 and the inclined portion 4cD2, and both are obtuse angles (θ1 > θ2 > 90°). However, θ2 may be other than an obtuse angle. Also in this example, the gain at a low elevation angle of the antenna device 10 can be improved. The V2X antenna 600D3 is located closer to the inclined portion 4cD1 than to the inclined portion 4cD2, but since the first angle θ1 formed by the inclined portion 4cD1 and the bottom surface is larger than the second angle θ2 formed by the inclined portion 4cD2 and the bottom surface, it is located closer to the second side than the first side described above.

[0064] ==Second Embodiment== FIG. 11A is a perspective view of a concave portion 4D4 according to an example of the second embodiment in which the V2X antenna 600D4 is arranged. FIG. 11B is a cross-sectional view of the concave portion 4D4 according to an example of the second embodiment in which the V2X antenna 600D4 is arranged.

[0065] The V2X antenna 600D4 is, for example, a monopole antenna, and the length of the element (here, the length of the V2X antenna 600D4 in the third direction Z) corresponds to approximately half a wavelength at a frequency of 5860 MHz. The V2X antenna 600D4 is disposed inside a recess 4D4 formed in the conductor roof 2A4. The V2X antenna 600D4 extends approximately parallel to the third direction Z. When viewed from the third direction Z, the recess 4D4 has an approximately circular shape. When viewed from the third direction Z, an inner surface 4dD of the recess 4D4 around the V2X antenna 600D4 in the XY plane direction is a conductor wall, and serves as a ground enclosure surrounding the V2X antenna 600D4. The inner surface 4dD of the recess 4D4 around the V2X antenna 600D4 in the XY plane direction is approximately perpendicular to the bottom surface of the recess 4D4 on the negative side of the third direction Z. When viewed from the third direction Z, the V2X antenna 600D4 is disposed approximately in the center of the recess 4D4.

[0066] Although not shown, the power supply unit of the V2X antenna 600D4 is located at the bottom end of the recess 4D4. The V2X antenna 600D4 transmits and receives radio waves by being fed with power from a coaxial cable (not shown) via a circuit board (not shown) electrically connected to the power supply unit. As described above, the V2X antenna 600 of this embodiment configures the antenna device 10 together with other antennas (AM antenna 200, FM antenna 300, DAB antenna 400, and GNSS antenna 700). However, the antenna device 10 may be configured with the V2X antenna 600D4 (similar to the V2X antenna 600D5 described later) as the V2X antenna 600, a power supply unit, a circuit board, and a coaxial cable. In other words, the antenna device 10 may be an antenna device that does not have other antennas as antennas and has only the V2X antenna 600. In addition, in the second embodiment, the V2X antenna 600D4 is described as an example of an antenna, but the present invention is not limited to this and can also be applied to a TEL antenna, a Wi-Fi antenna, or the like.

[0067] When viewed from the third direction Z, the diameter of the recess 4D4 in the XY plane direction (X4 shown in FIG. 11B) is approximately equal to an odd multiple of 1 / 2 the wavelength λ of the frequency that the V2X antenna 600D4 supports. In this case, the gain in the horizontal plane of the V2X antenna 600D4 can be increased regardless of the depth of the recess 4D4 in the third direction Z, compared to when the diameter of the recess 4D4 in the XY plane direction is different from an odd multiple of 1 / 2 the wavelength λ. The diameter of the recess 4D4 in the XY plane direction is, for example, 90% or more and 110% or less of (2N-1)λ / 2 (N is an integer of 1 or more). When viewed from the third direction Z, the V2X antenna 600D4 is disposed approximately at the center of the recess 4D4. In other words, the V2X antenna 600D4 is disposed at a position where the distance from the inner surface 4dD (X5 shown in FIG. 11B) is an odd multiple of 1 / 4 the wavelength λ.

[0068] Fig. 12 is a graph showing the relationship between the depth of the recess and the average gain in the horizontal plane of the V2X antenna 600D4. The horizontal axis of the graph shown in Fig. 12 indicates the depth of the recess 4D4 in the third direction Z (X3 shown in Fig. 11B) relative to the wavelength λ of the frequency supported by the V2X antenna 600D4. The vertical axis of the graph shown in Fig. 12 indicates the average gain (unit: dBi) in the horizontal plane of the V2X antenna 600D4. The graph shown in Fig. 12 shows plots for four cases in which the diameter of the recess 4D4 in the XY plane direction is 2.5λ, 3λ, 3.25λ, and 3.5λ.

[0069] 12, the recess 4D4 has a circular shape with a diameter of 500 mm as viewed from the third direction Z. The recess 4D4 is disposed in the center of the roof 2A4 as viewed from the third direction Z. The height of the V2X antenna 600D4 in the third direction Z is 27 mm (approximately half the wavelength at a frequency of 5860 MHz).

[0070] As shown in Fig. 12, when the diameter of the recess 4D4 in the XY plane direction is 3λ and 3.25λ, the average gain in the horizontal plane of the V2X antenna 600D4 decreases as the depth of the recess 4D4 in the third direction Z increases. In contrast, when the diameter of the recess 4D4 in the XY plane direction is 2.5λ and 3.5λ, the average gain in the horizontal plane of the V2X antenna 600D4 is almost constant regardless of the depth of the recess 4D4 in the third direction Z. From this result, it can be said that when the diameter of the recess 4D4 in the XY plane direction is approximately equal to an odd multiple of 1 / 2 the wavelength λ, the gain in the horizontal plane of the V2X antenna 600D4 can be increased regardless of the depth of the recess 4D4 in the third direction Z, compared to when the diameter of the recess 4D4 in the XY plane direction is different from an odd multiple of 1 / 2 the wavelength λ.

[0071] 13 is a perspective view of a V2X antenna 600D5 according to another example of the second embodiment. The description of the V2X antenna 600D5 is the same as that of the V2X antenna 600D4 described above.

[0072] When viewed from the third direction Z, the recess 4D5, which is formed in the roof 2A5 that is a conductor and has a conductive inner surface, has a substantially rectangular shape having a pair of short sides substantially parallel to the first direction X and a pair of long sides substantially parallel to the second direction Y. The V2X antenna 600D5 is disposed inside the recess 4D5. Specifically, when viewed from the third direction Z, the V2X antenna 600D5 is disposed approximately in the center of the recess 4D5 in the XY plane direction.

[0073] When viewed from the third direction Z, the V2X antenna 600D5 is surrounded by a ground enclosure 610D5 having an approximately circular shape as viewed from the third direction Z and an inner surface of which is a conductive wall. The ground enclosure 610D5 is disposed inside the recess 4D5. When viewed from the third direction Z, the ground enclosure 610D5 is approximately circular. An inner wall portion of the ground enclosure 610D5 surrounding the V2X antenna 600D5 in the XY plane direction is approximately perpendicular to the bottom surface of the recess 4D5 on the negative side of the third direction Z. The ground enclosure 610D5 is electrically connected to, for example, the roof 2A5.

[0074] When viewed from the third direction Z, the diameter of the ground enclosure 610D5 in the XY plane direction is approximately equal to an odd multiple of 1 / 2 the wavelength λ of the frequency that the V2X antenna 600D5 supports. Therefore, similar to the example described using Figs. 11A, 11B, and 12, the gain in the horizontal plane of the V2X antenna 600D5 can be increased regardless of the height of the ground enclosure 610D5 in the third direction Z. Furthermore, according to the example shown in Fig. 13, the gain in the horizontal plane of the V2X antenna 600D5 can be increased regardless of the size of the recess 4D5 in the XY plane direction or the depth of the recess 4D5 in the third direction Z. Therefore, the degree of freedom of the shape of the recess 4D5 can be improved.

[0075] Although the embodiments of the present invention have been described above with reference to the drawings, these are merely examples of the present invention, and various configurations other than those described above can also be adopted.

[0076] According to the present specification, the following aspects are provided.

[0077] (Aspect 1) In the first aspect, the antenna device 10 is provided with a V2X antenna 600D1 that is compatible with a predetermined frequency band and is partly disposed within a recess 4D1 that has an inclined portion rising from a bottom surface. The V2X antenna 600D1 is disposed at a position away from the upper end of the inclined portion that is inclined in a direction that forms an obtuse angle with the bottom surface.

[0078] The "wall" corresponds to the "inclined portion" in the above-mentioned embodiment. The "antenna" corresponds to the "V2X antenna 600D1" in the above-mentioned embodiment.

[0079] According to the above-described embodiment, the gain of the antenna device 10 at low elevation angles can be improved.

[0080] (Aspect 2) In the second aspect, the position away from the upper end of the inclined portion where the V2X antenna 600D1 is disposed is the bottom surface of the recess 4D1.

[0081] According to the above-described embodiment, the gain of the antenna device 10 at low elevation angles can be improved.

[0082] (Aspect 3) In the third aspect, the V2X antenna 600D1 is disposed at a position farther from the upper end of the inclined portion than from the lower end of the inclined portion.

[0083] According to the above-described embodiment, the gain of the antenna device 10 at low elevation angles can be improved.

[0084] (Aspect 4) In the fourth aspect, the V2X antenna 600D1 is disposed in a position surrounded by multiple inclined portions.

[0085] According to the above-described embodiment, the gain of the antenna device 10 at low elevation angles can be improved.

[0086] (Aspect 5) In the fifth aspect, the V2X antenna 600D1 is disposed at a position surrounded by inclined portions whose upper ends have an approximately quadrilateral shape in top view and which are inclined from at least some of the four sides of the approximately quadrilateral shape toward the bottom surface.

[0087] According to the above-described embodiment, the gain of the antenna device 10 at low elevation angles can be improved.

[0088] (Aspect 6) In the sixth aspect, the four sides include at least two opposing sides, and the V2X antenna 600D3 is located closer to one of the two opposing sides than the other side.

[0089] According to the above-described embodiment, the gain of the antenna device 10 at low elevation angles can be improved.

[0090] (Aspect 7) In the seventh embodiment, the angles formed by the bottom surface and the inclined portions inclined from each of the two opposing sides toward the bottom surface are different.

[0091] According to the above-described embodiment, the gain of the antenna device 10 at low elevation angles can be improved.

[0092] (Aspect 8) Aspect 8 is an antenna device 10 having a part disposed within a recess 4D4 having an inner wall portion 4dD rising from a bottom surface, and having a V2X antenna 600D4 corresponding to a predetermined frequency band, the V2X antenna 600D4 being disposed at a position where the distance from the inner wall portion 4dD, which has a circular shape in top view, is an odd multiple of a quarter wavelength of the predetermined frequency band.

[0093] The "wall" corresponds to the "inner wall portion 4dD" in the above-mentioned embodiment.

[0094] According to the above-described embodiment, the gain of the antenna device 10 at low elevation angles can be improved.

[0095] (Aspect 9) A ninth aspect is a vehicle having a recess 4D1 that has a bottom surface and an inclined portion formed to rise from the bottom surface, and that allows a V2X antenna 600D1 corresponding to a predetermined frequency band to be disposed on the bottom surface. The inclined portion is inclined in a direction such that the angle formed with the bottom surface is an obtuse angle.

[0096] The "wall" corresponds to the "inclined portion" in the above-mentioned embodiment.

[0097] According to the above-described embodiment, the gain of the antenna device 10 at low elevation angles can be improved.

[0098] (Aspect 10) A tenth aspect of the present invention is a vehicle having a bottom surface and an inner wall portion 4dD formed to rise from the bottom surface, and a recessed portion 4D4 having a circular shape in a top view. The recessed portion 4D4 enables a V2X antenna 600D4 corresponding to a predetermined frequency band to be disposed at a position where the distance from the inner wall portion 4dD is an odd multiple of a quarter wavelength of the predetermined frequency band.

[0099] The "wall" corresponds to the "inner wall portion 4dD" in the above-mentioned embodiment.

[0100] According to the above-described embodiment, the gain of the antenna device 10 at low elevation angles can be improved. [Explanation of symbols]

[0101] 4,4D1,4D2,4D3,4D4,4D5 Concave 4a,4aD1,4aD2,4aD3,4aD4,4bD1,4cD1,4cD2 Slope 4dD inner wall 10 Antenna device 600,600D1,600D2,600D3,600D4,600D5 V2X antenna

Claims

1. An antenna device, a part of which is disposed in a recess having a wall rising from a bottom surface, Equipped with an antenna corresponding to a predetermined frequency band, The antenna is disposed at a position away from an upper end of the wall that is inclined in a direction that forms an obtuse angle with the bottom surface. Antenna device.

2. The position away from the top end of the wall on which the antenna is disposed is the bottom surface.

2. The antenna device according to claim 1.

3. The antenna is disposed at a position farther from an upper end of the wall than from a lower end of the wall.

2. The antenna device according to claim 1.

4. The antenna is disposed at a position surrounded by the walls. An antenna device according to any one of claims 1 to 3.

5. the antenna is disposed at a position surrounded by a wall having an upper end that is substantially quadrilateral in shape when viewed from above, and that is inclined from at least some of the four sides of the substantially quadrilateral shape toward the bottom surface; 5. The antenna device according to claim 4.

6. The four sides include at least two opposing sides, The antenna is located closer to one of the two opposing sides than the other.

6. The antenna device according to claim 5.

7. The angles formed by the bottom surface and the walls inclined from each of the two opposing sides toward the bottom surface are different angles.

7. The antenna device according to claim 6.

8. An antenna device, a part of which is disposed in a recess having a wall rising from a bottom surface, having an antenna corresponding to a predetermined frequency band, the antenna is disposed at a position where the distance from a wall of the recess, which is circular in top view, is an odd multiple of a quarter wavelength of the predetermined frequency band; Antenna device.

9. A vehicle having a bottom surface and a wall formed to rise from the bottom surface, the vehicle having a recess in the bottom surface in which an antenna corresponding to a predetermined frequency band can be disposed, The wall is inclined in a direction such that the angle formed with the bottom surface is an obtuse angle. vehicle.

10. A vehicle having a bottom surface and a wall formed to rise from the bottom surface, the vehicle having a recess that is circular in top view, the recess allows an antenna corresponding to a predetermined frequency band to be disposed at a position whose distance from the wall is an odd multiple of a quarter wavelength of the predetermined frequency band; vehicle.

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