Antenna equipment

Abstract

This antenna device is disposed on a mobile body having a structural part, the antenna device being provided with an antenna element that is disposed apart from the structural part and corresponds to radio waves of a prescribed frequency band, and a reflective element for reflecting the radio waves, the reflective element being positioned between the structural part and the antenna element in the radiation direction of the radio waves.

Description

Technical Field

[0001] The present invention relates to an antenna device.

Background Art

[0002] Patent Document 1 describes an antenna disposed on a side mirror of a vehicle.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the antenna described in Patent Document 1, the directivity may deteriorate due to the influence of radio wave scattering in the vehicle body. Note that such deterioration of directivity is the same for antennas disposed outside the vehicle body.

[0005] An example of the object of the present invention is to suppress the deterioration of the directivity of an antenna due to radio wave scattering. Other objects of the present invention will become apparent from the description herein.

Means for Solving the Problems

[0006] One aspect of the present invention is an antenna device disposed on a moving body having a structural part, including an antenna element disposed apart from the structural part and corresponding to radio waves in a predetermined frequency band, and a reflecting element that reflects the radio waves, wherein the reflecting element is located between the structural part and the antenna element in the radiation direction of the radio waves.

[0007] According to the above aspect of the present invention, it is possible to suppress the deterioration of the directivity of the antenna due to radio wave scattering.

Brief Description of the Drawings

[0008] [Figure 1] This is a plan view of the mobile body 1 on which the antenna device 10 is located. [Figure 2A] This is a perspective view of the mobile body 1 on which the antenna device 10 is located. [Figure 2B] This is an enlarged perspective view of the area around the antenna device 10 on the mobile unit 1. [Figure 3A] This is a front view of antenna 11. [Figure 3B] This is a rear view of antenna 11. [Figure 4A] This is a top view of the antenna device 10. [Figure 4B] This is a front view of the antenna device 10. [Figure 4C] This is a rear view of the antenna device 10. [Figure 4D] This is a side view of the antenna device 10. [Figure 5A] This figure shows the radiation pattern of antenna 11 at an elevation angle E=0°. [Figure 5B] This figure shows the radiation pattern of antenna 11 at an elevation angle E = -6°. [Figure 5C] This figure shows the radiation pattern of antenna 11 at an elevation angle E = -3°. [Figure 5D] This figure shows the radiation pattern of antenna 11 at an elevation angle E=3°. [Figure 5E] This figure shows the radiation pattern of antenna 11 at an elevation angle E=6°. [Figure 5F] This figure shows the radiation pattern of antenna 11 at an elevation angle E=10°. [Figure 6] This is an enlarged perspective view of the area around the antenna device 10A on the mobile unit 1. [Figure 7A] This figure shows the radiation pattern of antenna 11A at an elevation angle E=0°. [Figure 7B] This figure shows the radiation pattern of antenna 11A at an elevation angle E = -6°. [Figure 7C]It is a diagram showing the radiation pattern of antenna 11A at an elevation angle E = -3°. [Figure 7D] It is a diagram showing the radiation pattern of antenna 11A at an elevation angle E = 3°. [Figure 7E] It is a diagram showing the radiation pattern of antenna 11A at an elevation angle E = 6°. [Figure 7F] It is a diagram showing the radiation pattern of antenna 11A at an elevation angle E = 10°. [Figure 8] It is a diagram showing the minimum gain of antenna 11 and antenna 11A. [Figure 9A] It is a diagram showing the relationship between the distance DX in antenna device 10 and the minimum gain of antenna 11. [Figure 9B] It is a diagram showing the relationship between the distance DY in antenna device 10 and the minimum gain of antenna 11. [Figure 9C] It is a diagram showing the relationship between the length LZ in antenna device 10 and the minimum gain of antenna 11. [Figure 10A] It is an explanatory diagram of antenna device 10B provided with compensation unit 30. [Figure 10B] It is an explanatory diagram of antenna device 10B with the position of compensation unit 30 changed. [Figure 11] It is a block diagram of the circuit of compensation unit 30. [Figure 12] It is an enlarged perspective view of the periphery of antenna device 10C in mobile body 1. [Figure 13] It is a diagram showing the radiation pattern of antenna 11C at an elevation angle E = 0°. [Figure 14A] It is a perspective view of antenna device 10D. [Figure 14B] It is a perspective view of antenna device 10E. [Figure 15A] It is an enlarged perspective view of the periphery of antenna device 10F in mobile body 1. [[ID=​​​​​​ [Figure 17A] This is an enlarged perspective view of the area around the antenna device 10H on the mobile unit 1. [Figure 17B] This is an enlarged perspective view of the area around the antenna device 10I on the mobile unit 1. [Figure 17C] This is an enlarged perspective view of the area around the antenna device 10J in the mobile unit 1. [Figure 17D] This is an enlarged perspective view of the area around the antenna device 10K in the mobile unit 1. [Figure 18] This figure shows the minimum gain of antenna 11 and antennas 11H to 11K. [Modes for carrying out the invention]

[0009] The following matters become clear from this specification and the accompanying drawings:

[0010] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The same or equivalent components, members, etc. shown in each drawing are denoted by the same reference numerals, and redundant explanations will be omitted as appropriate.

[0011] =!!!Execution!!!!!! Figure 1 is a plan view of the mobile body 1 on which the antenna device 10 is located. Figure 2A is a perspective view of the mobile body 1 on which the antenna device 10 is located. Figure 2B is an enlarged perspective view of the area around the antenna device 10 on the mobile body 1.

[0012] <<Definition of direction, etc.>> First, the directions (X direction, Y direction, and Z direction) of the antenna device 10 are defined with reference to Figures 1, 2A, and 2B.

[0013] The direction forward as viewed from the driver's seat of the mobile body 1 (in this embodiment, a vehicle) on which the antenna device 10 is located is defined as the +X direction (forward direction) of the antenna device 10. The direction to the left as viewed from the driver's seat of the mobile body 1 is defined as the +Y direction (left direction) of the antenna device 10, and the direction upward (zenith direction) as viewed from the driver's seat of the mobile body 1 is defined as the +Z direction (upward direction) of the antenna device 10. The opposite directions of the +X, +Y, and +Z directions are defined as the -X direction (rear direction), -Y direction (right direction), and -Z direction (downward direction), respectively. Each of the +X, -X, +Y, -Y, +Z, and -Z directions is a direction with a fixed orientation.

[0014] Furthermore, when referring to both the +X direction (forward) and the -X direction (backward), rather than a fixed direction as described above, it may simply be called the "X direction" or "forward / backward direction." Similarly, when referring to both the +Y direction (left) and the -Y direction (right), it may simply be called the "Y direction" or "left / right direction." Also, when referring to both the +Z direction (up) and the -Z direction (down), it may simply be called the "Z direction" or "up / down direction."

[0015] In Figures 1, 2A, and 2B, the +X direction (forward), +Y direction (left), and +Z direction (upward) are represented by line segments with arrows to facilitate understanding of the direction of the antenna device 10. Note that the intersection of these line segments with arrows does not represent the coordinate origin. Furthermore, the forward / backward direction or left / right direction may be called the "horizontal direction" or "width direction," and the up / down direction may be called the "vertical direction" or "height direction."

[0016] The definitions of directions and other terms described above are also common to other embodiments of this specification unless otherwise specified.

[0017] <<Overview of Antenna Device 10>> Next, with reference again to Figures 1, 2A, and 2B mentioned above, an overview of the antenna device 10 of this embodiment will be described.

[0018] Antenna device 10 is an antenna device placed on the mobile body 1. Here, "mobile body" refers to a moving vehicle. In this embodiment, the mobile body 1 is a vehicle. Here, "vehicle" refers to a vehicle having wheels. Therefore, in the following description, "mobile body 1" may be referred to as a "vehicle". However, the mobile body 1 is not limited to a vehicle and may be construction machinery, agricultural machinery, ships, aircraft, drones, etc., that do not have wheels.

[0019] As shown in Figures 1 and 2A, the mobile unit 1 has a structural unit 2 and side mirrors 3. In this embodiment, the structural unit 2 is the housing portion of the vehicle that constitutes the space for accommodating passengers, luggage, the engine, etc. That is, the structural unit 2 is the vehicle body, including the hood, roof, pillars, spoiler, bumper, etc. Therefore, in the following description, the "structural unit 2" may be referred to as the "vehicle body." The side mirrors 3 are mounted on the left and right sides of the vehicle body.

[0020] As shown in Figure 2A, the antenna device 10 of this embodiment is positioned on the side mirror 3. In other words, the antenna device 10 is positioned away from the vehicle body. However, the antenna device 10 may be positioned on a part of the vehicle other than the side mirror 3. For example, the antenna device 10 may be positioned away from parts such as the windshield, spoiler, or bumper. Furthermore, if the mobile body 1 is not a vehicle such as construction machinery or agricultural machinery, the antenna may be positioned on the housing portion that houses the prime mover such as the engine or motor, or on other parts suitable for communication by antenna.

[0021] As shown in Figures 2A and 2B, the side mirror 3 protrudes away from the vicinity of the vehicle's door. The side mirror 3 has a mirror (not shown) that reflects the side and rear of the vehicle, and a case 4. The driver of the vehicle can check the side and rear of the vehicle through the mirror.

[0022] The side mirror 3 may be a so-called camera-equipped side mirror or an electronic side mirror. Camera-equipped side mirrors and electronic side mirrors have a camera and an image display device. The camera, like the side mirror 3 shown in Figure 2A, protrudes away from the vicinity of the door of the vehicle body and is positioned to photograph the side and rear of the vehicle body. The image display device is connected to the aforementioned camera and displays the image captured by the camera. The image display device is, for example, a liquid crystal panel and is located inside the vehicle. With camera-equipped side mirrors and electronic side mirrors, the driver of the vehicle can check the side and rear of the vehicle body through the image captured by the camera.

[0023] In the following explanation, devices used to check the surroundings of the moving object 1, including the side mirror 3 shown in Figure 2B, as well as camera-equipped side mirrors and electronic side mirrors, may be referred to as surrounding confirmation devices.

[0024] As shown in Figure 2B, the antenna device 10 comprises an antenna 11 and a reflecting element 20.

[0025] Antenna 11 is an antenna for mobile communications, and is used, for example, in V2X (Vehicle to Everything: vehicle-to-vehicle communication, vehicle-to-infrastructure communication). Antenna 11 used in V2X corresponds to, for example, radio waves in the 5.9 GHz band. Note that "radio waves" may be referred to as "electromagnetic waves" in the following explanation. Antenna 11 is an antenna that corresponds to linearly polarized radio waves. Linear polarization is sometimes called vertical polarization when the polarization plane is perpendicular to the ground, and horizontal polarization when the polarization plane is horizontal to the ground.

[0026] Furthermore, the communication standards and frequency bands supported by antenna 11 are not limited to the 5.9GHz band used for V2X as described above, but may also be other communication standards and frequency bands. Antenna 11 may, for example, support radio waves in the 2.4GHz and 5GHz bands used for Wi-Fi (registered trademark), Bluetooth (registered trademark), etc. Antenna 11 may, for example, support radio waves in at least some of the frequency bands used for telematics, GSM, UMTS, LTE, and 5G.

[0027] Furthermore, antenna 11 may support MIMO (Multiple-Input Multiple-Output) communication. In MIMO communication, data is transmitted from each of the multiple antennas that make up antenna 11, and the data is received simultaneously by the multiple antennas. In addition, antenna 11 may be an antenna for keyless entry or an antenna for smart entry.

[0028] In this embodiment, antenna 11 is a dipole antenna. However, antenna 11 may be any antenna type other than a dipole antenna, as long as it is capable of handling linearly polarized radio waves. Antenna 11 may be, for example, a monopole antenna, sleeve antenna, collinear array antenna, dipole array antenna, slot array antenna, Yagi antenna, patch antenna, etc.

[0029] The antenna 11 in this embodiment is an omnidirectional antenna. However, due to influences from the vehicle's structural components 2 (vehicle body), it may be difficult to obtain the desired gain in a specific direction. Therefore, as described later, the desired directivity of the antenna 11 is achieved by changing its placement or by arranging multiple antennas 11 on the mobile unit 1 and employing a diversity system.

[0030] The antenna device 10 employing the diversity method has, for example, multiple (for example, two) antennas 11. Here, the two antennas 11 are positioned symmetrically (line-symmetrically) with respect to an axis along the X direction on the mobile body 1. In the diversity method, when signals are received by the two antennas 11, the larger of the received signals is selected. The overall directivity of the two antennas 11 is determined by superimposing the directivity of each individual antenna 11, and only the maximum gain is selected. As a result, the antenna device 10 employing the diversity method can obtain equivalent gain in all directions in the horizontal plane, thereby achieving the desired directivity.

[0031] In this embodiment, the antenna 11 is positioned on the vehicle's side mirror 3. As shown in Figure 2B, the antenna 11 is positioned inside a resin case 4 attached to the side mirror 3. When the antenna 11 is positioned on the side mirror 3, it is positioned as far away as possible from the vehicle's structural parts 2 (vehicle body). This is because the vehicle's structural parts 2 block radio waves, and if the antenna 11 were positioned close to the vehicle's structural parts 2, a large portion of the antenna 11's radiation direction would be blocked by the vehicle's structural parts 2.

[0032] Therefore, by positioning the antenna 11 as far away as possible from the vehicle's structural part 2 (vehicle body), the range over which the radio waves corresponding to the antenna 11 are shielded by the structural part 2 can be reduced, and the directivity range of the antenna 11 can be widened. Accordingly, the antenna 11 in this embodiment is positioned at the end of the side mirror 3 opposite to the side of the structural part 2 (the side in the +Y direction). However, the antenna 11 may also be positioned at the end of the side mirror 3 on the side of the structural part 2 (the side in the -Y direction). Alternatively, the antenna 11 may be positioned in the middle of the side mirror 3 in the lateral direction.

[0033] Furthermore, in this embodiment, the antenna 11 is positioned on the left-side mirror 3 of the vehicle. The mobile body 1 on which the antenna device 10 is positioned may have multiple antennas, including the antenna 11, that correspond to radio waves in the frequency band used for V2X, and these multiple antennas may be used in combination. In this case, the diversity method described above may be adopted as the directivity of the entire array of antennas positioned on the mobile body 1.

[0034] A coaxial cable 40 is connected to the antenna 11, as shown in Figure 2B. The coaxial cable 40 is a feed line connected to the antenna 11. As shown in Figure 3B, which will be described later, the coaxial cable 40 has an internal conductor, which is a signal line 41, and an external conductor, which is a ground line 42. Here, "connecting" is not limited to physical connection, but also includes "electrical connection." And "electrical connection" includes, for example, connecting objects with a conductor, or connecting them with electronic circuits, electronic components, etc.

[0035] Further details about antenna 11 will be provided later.

[0036] The reflective element 20 is a component that reflects the radio waves corresponding to the antenna 11. The reflective element 20 is formed, for example, at least in part, from a conductive material. The reflective element 20 may be composed of, for example, sheet metal, a substrate on which a conductive pattern is formed, a conductive film, etc. Alternatively, the reflective element 20 may be constructed by forming a conductive pattern in a resin material using MID (Molded Interconnect Device) technology.

[0037] In the case of radio waves in the frequency band used for V2X (5.9GHz band), the structural part 2 of the mobile body 1 is significantly larger than the wavelength of the radio wave, which can cause the radio waves corresponding to the antenna 11 to be strongly affected by scattering in the structural part 2.

[0038] Here, the statement that "the radio waves corresponding to antenna 11 are affected by scattering in structural part 2" is explained as follows. For example, the length of structural part 2 in the X direction of mobile body 1 is approximately 2500 to 4000 mm. Since the wavelength of the 5.9 GHz band, which is the frequency band used for the aforementioned V2X, is approximately 50 mm, structural part 2 is about 50 to 80 wavelengths in size when converted to the wavelength of the radio waves corresponding to antenna 11 (5.9 GHz). In other words, structural part 2 of mobile body 1 in this embodiment is very large relative to the wavelength of the 5.9 GHz band.

[0039] Antenna 11 transmits and receives radio waves in at least one of the following directions. Generally, when there is a conductive structure near the antenna, if the structure is approximately one-quarter or larger than the wavelength, some of the electromagnetic waves radiated from the antenna excite an electric current on the surface of the structure, becoming a new wave source. Then, radio waves are radiated from this new wave source (radio wave radiation shown by dashed lines in Figure 1), and this combined with the radiation from antenna 11 (radio wave radiation shown by solid lines in Figure 1) results in total radiation.

[0040] In this case, if the antenna device 10 does not have a reflector element 20, the radio waves directed toward the structural part 2 as shown in Figure 1 (radio waves shown by dashed lines in Figure 1) are scattered by the structural part 2. At this time, the radio waves directly radiated from the antenna 11 (radio waves shown by solid lines in Figure 1) and the radio waves scattered by the structural part 2 (radio waves shown by dashed lines in Figure 1) interfere with each other, resulting in directions in which the gain reinforces and directions in which the gain destructively cancels each other out when viewed from the antenna 11. In particular, as the distance between the antenna 11 and the structural part 2 increases, the interference path difference increases, and the gain deviation also increases. In other words, if the antenna 11 is positioned away from the structural part 2 (vehicle body) of the mobile body 1 as shown in Figure 1, the directivity range of the antenna 11 can be widened, but the gain deviation becomes larger. Consequently, a gain deviation occurs in a specific direction in the directivity of the antenna 11, and the communication performance deteriorates. In other words, the directivity of the antenna 11 deteriorates. In this embodiment, we describe radio waves in the frequency band used for V2X, but even with radio waves in high frequency bands other than V2X, the directivity of the antenna can deteriorate due to the strong influence of scattering in structural parts that are large relative to the wavelength.

[0041] In Figure 1, the arrows extending from the antenna 11 (dashed and solid lines) indicate a portion of the radiation directions of the antenna 11 in the horizontal plane. The dashed lines indicate the radiation direction toward the structural part 2 of the mobile body 1 (the direction of radio waves propagating to the structural part 2). The solid lines indicate the radiation directions other than those toward the structural part 2 of the mobile body 1.

[0042] In this embodiment, as shown in Figure 1, the reflecting element 20 is positioned between the structural part 2 of the mobile body 1 and the antenna element 12 (described later) of the antenna 11 in the direction of radio wave radiation. In other words, the reflecting element 20 is positioned between the structural part 2 of the mobile body 1 and the antenna element 12 of the antenna 11 in the direction of radiation indicated by the dashed arrow. This means that the reflecting element 20 is positioned in a location that can suppress the scattering of radio waves by the structural part 2. This suppresses the propagation of radio waves to the structural part 2, allowing for directivity in the desired direction while suppressing the occurrence of gain deviations. In other words, it is possible to suppress the deterioration of the directivity of the antenna 11 due to radio wave scattering.

[0043] Further details about the reflective element 20 will be provided later.

[0044] <<Details of Antenna 11 and Reflector 20>> Next, the antenna 11 and the reflector element 20 will be described in detail with reference to Figures 3A, 3B, and 4A to 4D.

[0045] Figure 3A is a front view of the antenna 11. Figure 3B is a rear view of the antenna 11. Figure 4A is a top view of the antenna device 10. Figure 4B is a front view of the antenna device 10. Figure 4C is a rear view of the antenna device 10. Figure 4D is a side view of the antenna device 10. Note that in Figures 3A and 3B, the reflective element 20 is omitted from the illustration of the antenna device 10 shown in Figure 2B, and only the antenna 11 portion is shown.

[0046] <Antenna 11> The antenna 11 comprises an antenna element 12 and a substrate 13.

[0047] The antenna element 12 is an element used in the frequency band of the radio waves corresponding to the antenna 11 (in this case, the 5.9 GHz band used for V2X). In this embodiment, the antenna element 12 is formed on the substrate 13. However, the antenna element 12 does not have to be formed on the substrate 13, for example. Also, if the antenna element 12 is not formed on the substrate 13, the antenna 11 does not have to have the substrate 13. For example, the element 12 may be made of sheet metal, a wire-shaped metal, or a conductive film.

[0048] As shown in Figures 3A and 3B, the antenna element 12 has a first element 14 and a second element 15. The first element 14 is an element extending in the +Z direction, to which the signal line 41 of the coaxial cable 40 is connected. The second element 15 is an element extending in the -Z direction, to which the ground line 42 of the coaxial cable 40 is connected. The first element 14 and the second element 15 constitute the antenna 11 as a dipole antenna. The first element 14 and the second element 15 of the antenna 11 have a shape (linear or rod-shaped) that extends in the Z direction. However, the elements of the antenna 11 are not limited to linear or rod-shaped, and may be formed in shapes such as semicircles, circles, ellipses, and polygons such as quadrilaterals.

[0049] The substrate 13 is a plate-shaped member on which the antenna element 12 is formed. In this embodiment, the substrate 13 in the antenna 11 is a printed circuit board (PCB). The substrate 13 is a rigid substrate, but is not limited to that and may be a flexible substrate. In addition to the antenna element 12, circuit elements such as filters may be separately provided on the substrate 13.

[0050] <Reflector element 20> As shown in Figures 4A to 4D, the reflective element 20 has a first reflective section 21, a second reflective section 22, and a third reflective section 23. In this embodiment, the first reflective section 21, the second reflective section 22, and the third reflective section 23 are connected, as shown in Figure 4A. This further suppresses the propagation of radio waves to the structural section 2. Furthermore, as shown in Figure 2B, the first reflective section 21, the second reflective section 22, and the third reflective section 23 are positioned to cover three sides of the antenna element 12 on the structural section 2 side (i.e., the -X direction side, the +X direction side, and the -Y direction side).

[0051] In this embodiment, the first reflecting section 21, the second reflecting section 22, and the third reflecting section 23 are connected, but they do not need to be connected if there are gaps between them or for other reasons. Also, a portion of the space between the first reflecting section 21, the second reflecting section 22, and the third reflecting section 23 may be connected.

[0052] The first reflective portion 21 is a component of the reflective element 20 located on the -X direction side. The second reflective portion 22 is a component of the reflective element 20 located on the +X direction side. The outer shapes of the first reflective portion 21 and the second reflective portion 22 are approximately rectangular, as shown in Figures 4B and 4C. Here, "approximately rectangular" is included in "approximately quadrilateral". Furthermore, "approximately quadrilateral" refers to a shape consisting of four sides, for example, where at least some of the corners are cut diagonally relative to the sides. Also, in the shape of an "approximately quadrilateral", some of the sides may have notches (recesses) or protrusions (convex parts). Note that the outer shapes of the first reflective portion 21 and the second reflective portion 22 may be approximate quadrilaterals other than approximately rectangular, or they may be shapes other than approximate quadrilaterals, such as semicircles, circles, ellipses, polygons, etc. Furthermore, the outer shapes of the first reflective portion 21 and the second reflective portion 22 may have a shape that bulges in the center.

[0053] As shown in Figure 4A, the first reflector 21 and the second reflector 22 are positioned so as to sandwich the antenna element 12 in the X direction. In other words, the antenna element 12 is located between the first reflector 21 and the second reflector 22 in the X direction. However, the first reflector 21 and the second reflector 22 may be positioned so as to sandwich the antenna element 12 in directions other than the X direction (for example, the Z direction). Furthermore, the first reflector 21 and the second reflector 22 do not have to be positioned so as to sandwich the antenna element 12.

[0054] The first reflector 21 and the second reflector 22 are arranged parallel to each other, as shown in Figure 4A. However, the first reflector 21 and the second reflector 22 do not have to be arranged parallel to each other. For example, when viewing the antenna device 10 in the direction of Figure 4A, the first reflector 21 and the second reflector 22 may be arranged so that they gradually open up (the distance between the first reflector 21 and the second reflector 22 increases) as you move in the +Y direction. Conversely, the first reflector 21 and the second reflector 22 may be arranged so that they gradually close up (the distance between the first reflector 21 and the second reflector 22 decreases) as you move in the +Y direction. The directivity of the antenna 11 can be changed by the angle of opening formed by the first reflector 21 and the second reflector 22.

[0055] The third reflector 23 is a component of the reflector element 20 located on the -Y direction side. The third reflector 23 is located between the structural part 2 of the moving body 1 and the antenna element 12 in the Y direction. The outer shape of the third reflector 23 is approximately rectangular, as shown in Figure 4D. However, the outer shape of the third reflector 23 may be an approximately quadrilateral other than an approximately rectangular shape, or a shape other than an approximately quadrilateral such as a semicircle, circle, ellipse, polygon, etc. Also, the outer shape of the third reflector 23 may be a shape that bulges in the center.

[0056] In this embodiment of the antenna device 10, as shown in Figure 4A, the coaxial cable 40 passes through the third reflector 23 and extends outwards towards the vehicle body (the side in the -Y direction). For this reason, an opening is formed in the third reflector 23 for inserting the coaxial cable 40.

[0057] As described above, in this embodiment, the first reflector 21, the second reflector 22, and the third reflector 23 are connected in shape and are positioned to cover three sides of the antenna element 12 on the structural part 2 side. However, the configuration of the reflector element 20 is not limited to this. The reflector element 20 may have only one of the first reflector 21, the second reflector 22, and the third reflector 23. Also, the reflector element 20 may have only two of the first reflector 21, the second reflector 22, and the third reflector 23. In other words, the reflector element 20 may be positioned between the moving body 1 and the antenna element 12 of the antenna 11 in the direction of radio wave radiation.

[0058] Furthermore, by positioning the reflective element 20 on the extension of the desired angular range from which radiation is to be radiated, as viewed from the antenna 11 (i.e., positioned between the structural part 2 of the mobile body 1 and the direction of radio wave radiation), the effect of mitigating the influence of the mobile body 1 in the desired angular range from which radiation is to be radiated is enhanced. In this embodiment, as will be described later, the first reflector 21 and the second reflector 22 are positioned in front of and behind the antenna element 12 in order to obtain the effect of widening the angular range in the front-to-back direction within the range to the left of the mobile body 1. In addition, for example, as shown in Figures 17A to 17D described later, by adding a reflective element in the vertical direction of the antenna element 12, the effect of mitigating the influence of the mobile body 1 in the vertical angular range of the mobile body 1 is also obtained.

[0059] Furthermore, as shown in Figure 4A, the reflective element 20 has a roughly U-shape when viewed in the -Y direction, but it may also have other shapes such as a V-shape, Y-shape, or X-shape.

[0060] Further explanations of "DY" shown in Figure 4A, "LZ" shown in Figures 4B and 4C, and "DX1" and "DX2" shown in Figure 4D will be provided later.

[0061] <<Characteristics of the antenna device 10 equipped with a reflecting element 20>> Next, the characteristics of the antenna device 10 of this embodiment, which includes the reflecting element 20, will be described with reference to Figures 5A to 5F.

[0062] Figure 5A shows the radiation pattern of antenna 11 of antenna device 10 at an elevation angle E=0°.

[0063] Here, as shown in Figures 2A and 2B above, when the angle with respect to the +Z direction (zenith direction) is denoted as angle θ, the elevation angle E is defined as E = 90° - θ. In other words, the elevation angle E is the angle from the horizontal direction. When the elevation angle E is a positive value, it is the direction pointing upwards from the horizontal direction, and when the elevation angle E is a negative value, it is the direction pointing downwards from the horizontal direction.

[0064] The radiation pattern of antenna 11 shown in Figure 5A represents its directivity in the horizontal plane. As described above, antenna 11 is positioned on the left side mirror 3 of the mobile body 1. In this case, antenna 11 is affected by the structural part 2 located to the right of the side mirror 3, making it difficult to obtain the desired gain in the range to the right of the mobile body 1. Therefore, the directivity of antenna 11 positioned on the left side mirror 3 of the mobile body 1 is considered to be the directivity in the range to the left of the mobile body 1, that is, in the case of Figure 5A, in the range of angle 0° to angle 180°.

[0065] In the radiation pattern of antenna 11 shown in Figure 5A, the direction at an angle of 0° corresponds to the +X direction, the direction at an angle of 90° corresponds to the +Y direction, the direction at an angle of 180° corresponds to the -X direction, and the direction at an angle of 270° corresponds to the -Y direction.

[0066] As mentioned above, the mobile body 1 may be equipped with multiple antennas, including antenna 11, that correspond to radio waves in the frequency band used for V2X, and a diversity method may be adopted for the directivity of the entire array of antennas on the mobile body 1. For example, another antenna 11 may be placed on the right side mirror of the mobile body 1, and the larger of the signals transmitted or received by the left and right antennas 11 may be selected. This makes it possible to obtain the desired directivity in all directions within the horizontal plane of the mobile body 1.

[0067] As shown in Figure 5A, the antenna 11 of this embodiment exhibits low ripple and good directivity in the range of 0° to 180°, which is the left side of the mobile body 1.

[0068] Figure 5B shows the radiation pattern of antenna 11 at an elevation angle E = -6°. Figure 5C shows the radiation pattern of antenna 11 at an elevation angle E = -3°. Figure 5D shows the radiation pattern of antenna 11 at an elevation angle E = 3°. Figure 5E shows the radiation pattern of antenna 11 at an elevation angle E = 6°. Figure 5F shows the radiation pattern of antenna 11 at an elevation angle E = 10°.

[0069] As shown in Figures 5B to 5F, the antenna 11 of this embodiment exhibits low ripple and good directivity not only at an elevation angle E=0°, but also in the elevation angle range E=-6° to 10°. Therefore, the antenna 11 of this embodiment exhibits low ripple and good directivity in the elevation angle range E=-6° to 10° within the angle range of 0° to 180°, which is the left side of the mobile body 1.

[0070] <<Comparative Example>> The characteristics of the antenna 11 of this embodiment described above will be explained by comparing it with the comparative example antenna 11A (antenna device 10A) with reference to Figures 6 to 8.

[0071] Figure 6 is an enlarged perspective view of the area around the antenna device 10A on the mobile unit 1.

[0072] The comparative example antenna device 10A includes an antenna 11A. Antenna 11A, like antenna 11 in this embodiment, is an antenna that corresponds to radio waves in the frequency band used for V2X and is configured as a dipole antenna. However, unlike antenna device 10 in this embodiment, the comparative example antenna device 10A does not include a reflector element 20. Also, antenna device 10A is a verification model, and the mobile body 1 on which antenna device 10A is placed does not have a side mirror 3.

[0073] A coaxial cable 40 is connected to the antenna 11A of the antenna device 10A. In Figure 6, the coaxial cable 40 connected to the antenna 11A is shown by a dashed line. Also, for the purpose of explaining this as a verification model, the configuration of the antenna device 10A other than the antenna 11A is omitted from Figure 6. For example, the antenna device 10A may have a support member to support the antenna 11A, or the antenna element 12A of the antenna 11A may be formed on a substrate, as is the case with the antenna 11 of the antenna device 10 in this embodiment. Details of the other antennas 11A are the same as those of the antenna 11, so their explanation is omitted.

[0074] Figure 7A shows the radiation pattern of antenna 11A at an elevation angle E=0°.

[0075] The radiation pattern of the comparative example antenna 11A shown in Figure 7A exhibits horizontal directivity at an elevation angle E=0°, similar to the radiation pattern of antenna 11 in this embodiment shown in Figure 5A. Compared to the radiation pattern of antenna 11A shown in Figure 5A, antenna 11A exhibits significantly more ripple. Specifically, antenna 11A shows a substantial gain deviation. In particular, antenna 11A has a gain deviation of nearly 20 dB between its maximum and minimum gain values.

[0076] This is because, in the comparative example antenna device 10A, as described above, the radio waves directly radiated from antenna 11A (shown by solid lines in Figure 1) and the radio waves scattered by structural part 2 (shown by dashed lines in Figure 1) interfere with each other, resulting in directions where the gain reinforces and directions where the gain cancels out when viewed from antenna 11A. This leads to a significant gain deviation, which worsens the directivity of antenna 11A.

[0077] Figure 7B shows the radiation pattern of antenna 11A at an elevation angle E = -6°. Figure 7C shows the radiation pattern of antenna 11A at an elevation angle E = -3°. Figure 7D shows the radiation pattern of antenna 11A at an elevation angle E = 3°. Figure 7E shows the radiation pattern of antenna 11A at an elevation angle E = 6°. Figure 7F shows the radiation pattern of antenna 11A at an elevation angle E = 10°.

[0078] Furthermore, as shown in Figures 7B to 7F, the comparative example antenna 11A exhibits significant ripple not only at an elevation angle E=0° but also in the elevation angle range E=-6° to 10°, resulting in a deterioration of the antenna's directivity. In other words, the comparative example antenna 11A shows a significant gain deviation in the elevation angle range E=-6° to 10°.

[0079] Figure 8 shows the minimum gain of antenna 11 and antenna 11A.

[0080] In the following, we will limit the comparison to a predetermined angular range (here, 10° to 160°) within the range to the left of the mobile body 1 (0° to 180°), and compare the minimum gain of the antenna 11 of this embodiment at an elevation angle E=0° with the minimum gain of the comparative example antenna 11A at an elevation angle E=0°. Here, "minimum gain" refers to the minimum value of the gain within the predetermined angular range (here, 10° to 160°). The reason for excluding angles outside the predetermined angular range (here, 0° to 10° and 160° to 180°) is that the influence of the structural part 2 of the mobile body 1 is significant outside the predetermined angular range, making it difficult to obtain the desired gain.

[0081] As shown in Figure 8, at an elevation angle E=0°, the comparative antenna 11A has a significantly lower minimum gain compared to the antenna 11 of this embodiment. In other words, the comparative antenna 11A has a larger gain deviation and a larger drop in minimum gain compared to the antenna 11 of this embodiment.

[0082] Although a detailed comparison of the results is omitted here, the comparative antenna 11A exhibits significantly lower minimum gain compared to the antenna 11 of this embodiment, not only at an elevation angle E=0° but also in the elevation angle range E=-6° to 10°. In other words, the comparative antenna 11A shows a larger gain deviation and a greater drop in minimum gain compared to the antenna 11 of this embodiment in the elevation angle range E=-6° to 10°.

[0083] As described above, the antenna device 10 of this embodiment includes a reflective element 20 located between the structural part 2 and the antenna element 12 in the direction of radio wave radiation, thereby suppressing the propagation of radio waves to the structural part 2 and preventing gain deviations while maintaining the desired directivity. Therefore, it is possible to suppress the deterioration of the directivity of the antenna 11 due to radio wave scattering.

[0084] <<Verification of dimensions, etc., of the reflector element 20>> Next, referring again to Figures 4A to 4D mentioned above, and with reference to Figures 9A to 9C, we will examine the preferred dimensions of the reflective element 20.

[0085] As described above, in the antenna device 10 of this embodiment, the first reflecting portion 21 and the second reflecting portion 22 of the reflecting element 20 are positioned in the X direction so as to sandwich the antenna element 12 of the antenna 11. Here, the distance in the X direction between the antenna element 12 and the reflecting element 20 (first reflecting portion 21 and second reflecting portion 22) is preferably an appropriate distance, neither too close nor too far apart. This is because if the antenna element 12 and the reflecting element 20 are too close in the X direction, it will affect the radiation of radio waves by the antenna 11, and if the antenna element 12 and the reflecting element 20 are too far apart, the effect of suppressing radio wave scattering in the structural portion 2 will be weakened.

[0086] To verify the appropriate distance in the X direction, we first define a first distance DX1 and a second distance DX2. The first distance DX1 is the distance in the X direction between the surface of the first reflector 21 on the antenna element 12 (antenna 11) side and the antenna element 12, as shown in Figure 4D. The second distance DX2 is the distance in the X direction between the surface of the second reflector 22 on the antenna element 12 (antenna 11) side and the antenna element 12, as shown in Figure 4D.

[0087] Furthermore, an appropriate distance is preferred for the distance in the Y direction between the antenna element 12 and the reflecting element 20 (third reflecting part 23). This is because if the antenna element 12 and the reflecting element 20 are too close in the Y direction, it is thought that it will affect the radiation of radio waves by the antenna 11.

[0088] To verify the appropriate distance in the Y direction, a third distance DY is defined. The third distance DY is the distance in the Y direction between the surface of the third reflector 23 on the antenna element 12 (antenna 11) side and the antenna element 12, as shown in Figure 4A.

[0089] Furthermore, in order to verify the appropriate length of the reflective element 20 in the Z direction, a length LZ is defined. Length LZ is the length of the reflective element 20 in the Z direction, as shown in Figures 4B and 4C.

[0090] Figure 9A shows the relationship between the distance DX in the antenna device 10 and the minimum gain of the antenna 11.

[0091] Figure 9A shows the relationship of the minimum gain of antenna 11 when the first distance DX1 and the second distance DX2 are kept equal and the first distance DX1 and the second distance DX2 are varied. Therefore, the distance DX in the antenna device 10 shown in Figure 9A represents both the first distance DX1 and the second distance DX2 described above. According to the graph in Figure 9A, it can be seen that the minimum gain of antenna 11 decreases sharply when the distance DX exceeds 15 mm. For this reason, the distance DX is preferably 15 mm or less, and more preferably 5 mm or more and 10 mm or less.

[0092] When the above-mentioned preferred range of distance DX is converted in terms of the wavelength of the radio wave frequency (5.9 GHz) to which the antenna 11 corresponds, the distance DX is preferably one-third or less of the wavelength of the radio wave to which the antenna 11 corresponds, and more preferably one-tenth to one-fifth of the wavelength of the radio wave to which the antenna 11 corresponds.

[0093] Furthermore, the above description refers to the preferred range of distances when the first distance DX1 and the second distance DX2 are the same. Specifically, both the first distance DX1 and the second distance DX2 are preferably one-third or less of the wavelength of the radio wave to which the antenna 11 corresponds, and more preferably one-tenth to one-fifth of the wavelength of the radio wave to which the antenna 11 corresponds. However, either the first distance DX1 or the second distance DX2 may be preferably one-third or less of the wavelength of the radio wave to which the antenna 11 corresponds, and more preferably one-tenth to one-fifth of the wavelength of the radio wave to which the antenna 11 corresponds.

[0094] Figure 9B shows the relationship between the distance DY in the antenna device 10 and the minimum gain of the antenna 11.

[0095] As shown in the graph in Figure 9B, the minimum gain of antenna 11 decreases significantly when the distance DY is less than 4 mm. Therefore, the distance DY is preferably 4 mm or more, and more preferably 5 mm or more.

[0096] When the above-mentioned preferred range of distance DY is converted to the wavelength of the radio wave frequency (5.9 GHz) to which the antenna 11 corresponds, the distance DY is preferably one-tenth or more of the wavelength of the radio wave to which the antenna 11 corresponds.

[0097] Figure 9C shows the relationship between the length LZ in the antenna device 10 and the minimum gain of the antenna 11.

[0098] As shown in the graph in Figure 9C, the minimum gain of antenna 11 decreases significantly when the length LZ is less than 25 mm. Therefore, the length LZ is preferably 25 mm or more.

[0099] <<Compensation Department 30>> In the case of an antenna that corresponds to the frequency band used for V2X as in this embodiment, signal loss may increase when the coaxial cable connected to the antenna is routed. The antenna device of this embodiment may further have a compensation unit to compensate for the gain due to such signal loss. Therefore, with reference to Figures 10A, 10B and 11, an antenna device 10B equipped with a compensation unit 30 will be described.

[0100] Figure 10A is an explanatory diagram of the antenna device 10B equipped with a compensation unit 30. Figure 10B is an explanatory diagram of the antenna device 10B with the position of the compensation unit 30 changed. Figure 11 is a block diagram of the circuit of the compensation unit 30.

[0101] The antenna device 10B comprises an antenna 11B, a reflecting element 20B, and a compensation unit 30. The antenna 11B is the same antenna as the antenna 11 of this embodiment described above, and has an antenna element 12B. The reflecting element 20B is the same reflecting element as the reflecting element 20 described above, and is positioned to cover three sides of the antenna element 12B on the structural part 2 side (i.e., the -X direction side, the +X direction side, and the -Y direction side).

[0102] The compensation unit 30 is a device that compensates for the gain lost due to signal loss in the coaxial cable connected to the antenna 11B. The compensation unit 30 is connected between the antenna 11B and the ECU 50 (Electronic Control Unit). As shown in Figure 11, the compensation unit 30 includes a first amplifier 31, a second amplifier 32, and a switch 33.

[0103] The first amplifier 31 is an amplifier (a so-called power amplifier) ​​that amplifies the radio waves transmitted by antenna 11B. The second amplifier 32 is an amplifier (a so-called low-noise amplifier) ​​that amplifies the radio waves received by antenna 11B. Switch 33 is a switch that switches between a path including the first amplifier 31 and a path including the second amplifier 32. In other words, the compensation unit 30 has circuits that amplify the signals transmitted and received by antenna 11B. Here, "path" refers to the route through which the signal travels.

[0104] Furthermore, the compensation unit 30 and the ECU 50 exchange signals including power to operate the first amplifier 31 and the second amplifier 32, signals to instruct the switching of the switch 33, signals to transmit the amplification factor of the compensation unit 30 to the ECU 50 in real time, and signals used for communication with other terminals via the antenna 11B. In addition, each of these signals may be communicated between the compensation unit 30 and the ECU 50 via the same coaxial cable. Alternatively, each of these signals may be communicated via different coaxial cables, or only partially via the same coaxial cable.

[0105] In the antenna device 10B of this embodiment, the compensation unit 30 is arranged inside the side mirror 3 together with the antenna 11B and the reflecting element 20B, as shown in Figure 10A. That is, the compensation unit 30 is positioned close to the antenna 11B. At this time, the reflecting element 20B is positioned between the compensation unit 30 and the antenna element 12B in the direction of radio wave radiation. This makes it possible to suppress the influence of radio waves from the antenna 11B on the compensation unit 30 (particularly the first amplifier 31 and the second amplifier 32). In other words, the reflecting element 20B reflects the radio waves corresponding to the antenna 11 and can also function as a shield cover for the compensation unit 30. This makes it easy to achieve space saving and integration of the antenna device 10B. However, the compensation unit 30 may be arranged outside the side mirror 3, as shown in Figure 10B.

[0106] ==Modified Examples of Reflectors== <<Side mirror 3 that functions as a reflector>> As described above, the reflecting element 20 of the antenna device 10 is a component that reflects the radio waves corresponding to the antenna 11, and is made of a conductive material. The reflecting element may be in a form other than the reflecting element 20 described above. For example, as shown in Figure 12, the side mirror 3 of the mobile body 1 is made of a conductive material, so the side mirror 3 may also function as a reflecting element.

[0107] Figure 12 is an enlarged perspective view of the area around the antenna device 10C on the mobile unit 1.

[0108] Antenna device 10C comprises an antenna 11C and a reflector element 20C. Antenna 11C is the same antenna as antenna 11A in the comparative example described above, and has an antenna element 12C. In antenna device 10C, the reflector element 20C may be the side mirror 3 of the mobile body 1. The reflector element 20C, which is the side mirror 3, is located on the rear side (-X direction side) of the antenna element 12C.

[0109] Figure 13 shows the radiation pattern of antenna 11C at an elevation angle E=0°.

[0110] Figure 13 shows the radiation pattern in the horizontal plane, similar to Figure 5A described above. As shown in Figure 13, antenna 11C has little ripple and good directivity in the range of 90° to 180°, where the reflector element 20C is positioned, within the range of 0° to 180°. However, there are areas in the range of 0° to 90° where the gain deviation is large. If such a range with a large gain deviation is acceptable, antenna 11C may be positioned where the side mirror 3 of the mobile body 1 functions as a reflector element.

[0111] Figure 13 describes the radiation pattern of antenna 11C at an elevation angle E=0°. Although detailed verification results are omitted, antenna 11C exhibits good directivity with minimal ripple not only at an elevation angle E=0°, but also in the elevation angle range of E=-6° to 10°, within the range of angles 90° to 180° where the reflector element 20C is positioned.

[0112] <<Linear section 24>> The reflective element may be in a form other than that of the reflective element 20 described above. For example, as shown in Figures 14A and 14B, the side mirror 3 of the moving body 1 may be composed of multiple linear parts that reflect linearly polarized radio waves.

[0113] Figure 14A is a perspective view of the antenna device 10D.

[0114] The antenna device 10D comprises an antenna 11D and a reflecting element 20D. Antenna 11D is the same antenna as antenna 11 in the embodiment described above and has an antenna element 12D. The reflecting element 20D is composed of a plurality of linear portions 24. Each of the linear portions 24 is made of a conductor and extends in the Z direction so that antenna 11D reflects radio waves of the corresponding linear polarization. This also helps to suppress deterioration of the directivity of antenna 11D due to radio wave scattering. The reflecting element 20D may be made of, for example, sheet metal, a linear conductor, or a conductor pattern printed on a substrate.

[0115] Figure 14B is a perspective view of the antenna device 10E.

[0116] The antenna device 10E comprises an antenna 11E and a reflecting element 20E. Antenna 11E is the same antenna as antenna 11 in the above-described embodiment and has an antenna element 12E. The reflecting element 20E is composed of a plurality of linear portions 24, the same as the reflecting element 20D described above, and a bridging portion 25 that connects the plurality of linear portions 24 in the lateral direction. Each of the linear portions 24 is made of a conductor and extends in the Z direction so that antenna 11D reflects radio waves of the corresponding linear polarization. This also suppresses deterioration of the directivity of antenna 11E due to radio wave scattering. In the antenna device 10E, the bridging portion 25 connects the plurality of linear portions 24, supporting the plurality of linear portions 24 while further suppressing the propagation of radio waves to the structural portion 2, thereby suppressing scattering in the structural portion 2. The reflecting element 20E may be made of, for example, sheet metal, a linear conductor, or a conductor pattern printed on a substrate.

[0117] <<Other variations>>> As described above, the reflecting element 20 of the antenna device 10 had a first reflecting section 21, a second reflecting section 22, and a third reflecting section 23. However, the reflecting element 20 may have only some of the first reflecting section 21, the second reflecting section 22, and the third reflecting section 23 (only two of them, or only one of them), as in the antenna devices 10F and 10G described later.

[0118] Figure 15A is an enlarged perspective view of the area around the antenna device 10F on the mobile unit 1. Figure 15B is an enlarged perspective view of the area around the antenna device 10G on the mobile unit 1.

[0119] As shown in Figure 15A, the reflecting element 20F of the antenna device 10F has only a first reflecting section 21F and a second reflecting section 22F. In other words, the reflecting element 20F of the antenna device 10F does not have a third reflecting section 23 compared to the reflecting element 20 of the antenna device 10 shown in Figure 2B above.

[0120] Furthermore, the reflecting element 20G of the antenna device 10G has only a third reflecting section 23, as shown in Figure 15B. In other words, the reflecting element 20G of the antenna device 10G does not have a first reflecting section 21 and a second reflecting section 22, compared to the reflecting element 20 of the antenna device 10 shown in Figure 2B above.

[0121] Figure 16 shows the minimum gain of antenna 11, antenna 11F, and antenna 11G.

[0122] In Figure 16, within the range to the left of the moving body 1 (0° to 180°), we limit the range to a predetermined angular range (here, 10° to 160°) and compare the minimum gain of antenna 11 in this embodiment, as shown in Figure 8 above, with the minimum gains of antennas 11F and 11G at an elevation angle E=0°.

[0123] As shown in Figure 16, although the minimum gain of antenna 11G is slightly lower, the minimum gains of antennas 11F and 11G are almost the same as the minimum gain of antenna 11. While a detailed comparison of the results is omitted here, the minimum gains of antennas 11F and 11G are almost the same as the minimum gain of antenna 11 not only at elevation angle E=0°, but also in the elevation angle range E=-6° to 10°.

[0124] In other words, in antenna devices 10F and 10G, just like in antenna device 10, the propagation of radio waves to the structural part 2 can be suppressed, and the gain deviation can be suppressed while maintaining the desired directivity. Therefore, the deterioration of the directivity of antennas 11F and 11G due to radio wave scattering can be suppressed.

[0125] As described above, the reflecting element 20 of the antenna device 10 had a first reflecting section 21, a second reflecting section 22, and a third reflecting section 23. However, the reflecting element 20 may have at least a portion of the first reflecting section 21, the second reflecting section 22, and the third reflecting section 23, as in the antenna devices 10H to 10J described later, and may also have additional reflecting sections (reflecting sections arranged on the upper and lower sides of the antenna element).

[0126] Figure 17A is an enlarged perspective view of the area around antenna device 10H on the mobile unit 1. Figure 17B is an enlarged perspective view of the area around antenna device 10I on the mobile unit 1. Figure 17C is an enlarged perspective view of the area around antenna device 10J on the mobile unit 1.

[0127] As shown in Figure 17A, the reflecting element 20H of the antenna device 10H has a first reflecting section 21H, a second reflecting section 22H, and a third reflecting section 23H. Furthermore, the reflecting element 20H has a fourth reflecting section 26H located above the antenna element 12H and a fifth reflecting section 27H located below the antenna element 12H. In other words, the reflecting element 20H of the antenna device 10H has the fourth reflecting section 26H and the fifth reflecting section 27H in addition to the reflecting element 20 of the antenna device 10 shown in Figure 2B described above.

[0128] The reflecting element 20I of the antenna device 10I has a first reflecting section 21I and a second reflecting section 22I, as shown in Figure 17B. Furthermore, the reflecting element 20I has a fourth reflecting section 26I located above the antenna element 12I and a fifth reflecting section 27I located below the antenna element 12I. In other words, the reflecting element 20I of the antenna device 10I has the fourth reflecting section 26I and the fifth reflecting section 27I in addition to the reflecting element 20F of the antenna device 10F shown in Figure 15A above.

[0129] The reflecting element 20J of the antenna device 10J has a third reflecting section 23J, as shown in Figure 17C. Furthermore, the reflecting element 20J has a fourth reflecting section 26J located above the antenna element 12J and a fifth reflecting section 27J located below the antenna element 12J. In other words, the reflecting element 20J of the antenna device 10J has the fourth reflecting section 26J and the fifth reflecting section 27J in addition to the reflecting element 20G of the antenna device 10G shown in Figure 15B described above.

[0130] Figure 17D is an enlarged perspective view of the area around the antenna device 10K in the mobile unit 1.

[0131] As a reference example of the antenna devices 10H to 10J described above, in antenna device 10K, the reflecting element 20 is composed only of reflecting parts positioned above and below the antenna element. That is, as shown in Figure 17D, the reflecting element 20K of antenna device 10K has only the fourth reflecting part 26K and the fifth reflecting part 27K.

[0132] Figure 18 shows the minimum gain of antenna 11 and antennas 11H to 11K.

[0133] In Figure 18, within the range to the left of the moving body 1 (0° to 180°), we limit the range to a predetermined angle (here, 10° to 160°) and compare the minimum gain of antenna 11 in this embodiment, as shown in Figure 8 above, with the minimum gains of antennas 11H to 11K at an elevation angle E=0°.

[0134] As shown in Figure 18, the minimum gains of antennas 11H and 11I are greater than the minimum gain of antenna 11. Furthermore, the minimum gain of antenna 11J is slightly less than that of antenna 11, but is almost equivalent. While a detailed comparison is omitted here, the minimum gains of antennas 11H and 11I are greater than that of antenna 11 not only at elevation angle E=0°, but also in the elevation angle range E=-6° to 10°. Additionally, the minimum gain of antenna 11J is almost equivalent to that of antenna 11 in the elevation angle range E=-6° to 10°.

[0135] In other words, with antenna devices 10H to 10J, just like with antenna device 10, the propagation of radio waves to the structural part 2 can be suppressed, and the gain deviation can be suppressed while maintaining the desired directivity. Therefore, the deterioration of the directivity of antennas 11H to 11J due to radio wave scattering can be suppressed. Furthermore, by adding reflective parts to the upper and lower sides of the antenna element, as in antenna device 10H and antenna device 10I, the propagation of radio waves to the structural part 2 can be further suppressed, and the gain deviation can be further suppressed while maintaining the desired directivity.

[0136] As shown in Figure 18, at an elevation angle E=0°, the reference example antenna 11K has a significantly smaller minimum gain compared to the antenna 11 of this embodiment and the modified antennas 11H to 11J. Although a detailed comparison figure is omitted, not only at an elevation angle E=0°, but also in the elevation angle range of E=-6° to 10°, the reference example antenna 11K has a significantly smaller minimum gain compared to the antenna 11 of this embodiment and the modified antennas 11H to 11J. In other words, the reflective sections placed on the upper and lower sides of the antenna element are not very effective in suppressing the deterioration of the antenna's directivity on their own, and are merely additional elements.

[0137] The embodiments and modifications of the present invention have been described above with reference to the drawings, but these are merely examples of the present invention, and various other configurations can also be adopted.

[0138] ==Summary== According to this specification, antenna devices in the following embodiments are provided.

[0139] (Aspect 1) Embodiment 1 is an antenna device 10 arranged on a mobile body 1 having a structural part 2, comprising an antenna element 12 arranged spaced apart from the structural part 2 and corresponding to radio waves in a predetermined frequency band, and a reflecting element 20 that reflects radio waves, wherein the reflecting element 20 is located between the structural part 2 and the antenna element 12 in the direction of radio wave radiation.

[0140] According to the above-described embodiment, it is possible to suppress the deterioration of the antenna's directivity due to radio wave scattering.

[0141] (Aspect 2) In embodiment 2, the reflecting element 20 has a first reflecting portion 21 and a second reflecting portion 22, and in a second direction perpendicular to the first direction in which the antenna element 12 moves away from the structural portion 2, the antenna element 12 is located between the first reflecting portion 21 and the second reflecting portion 22.

[0142] The "first direction" corresponds to the "Y direction" in the above-described embodiment. The "second direction" corresponds to the "X direction" in the above-described embodiment.

[0143] According to the above-described embodiment, the deterioration of antenna directivity due to radio wave scattering can be further suppressed.

[0144] (Aspect 3) In embodiment 3, at least one of the first distance in the second direction between the first reflector 21 and the antenna element 12, and the second distance in the second direction between the second reflector 22 and the antenna element 12, is one-third or less of the wavelength of the radio wave.

[0145] "First distance" corresponds to "distance DX1" in the above-described embodiment. "Second distance" corresponds to "distance DX2" in the above-described embodiment.

[0146] According to the above-described embodiment, the deterioration of antenna directivity due to radio wave scattering can be further suppressed.

[0147] (Aspect 4) In embodiment 4, at least one of the first distance and the second distance is between one-tenth and one-fifth of the wavelength of the radio wave.

[0148] According to the above-described embodiment, the deterioration of antenna directivity due to radio wave scattering can be further suppressed.

[0149] (Appendix 5) In embodiment 5, the reflecting element 20 has a third reflecting portion 23 located between the structural portion 2 and the antenna element 12 in the first direction.

[0150] According to the above-described embodiment, the deterioration of antenna directivity due to radio wave scattering can be further suppressed.

[0151] (Aspect 6) In embodiment 6, the third distance in the first direction between the third reflector 23 and the antenna element 12 is one-tenth or more of the wavelength of the radio wave.

[0152] The "third distance" corresponds to the "distance DY" in the above-described configuration.

[0153] According to the above-described embodiment, the deterioration of antenna directivity due to radio wave scattering can be further suppressed.

[0154] (Aspect 7) In embodiment 7, when the reflective element 20 is viewed in a direction perpendicular to the first and second directions, the first reflective portion 21, the second reflective portion 22, and the third reflective portion 23 are connected in shape.

[0155] According to the above-described embodiment, the deterioration of antenna directivity due to radio wave scattering can be further suppressed.

[0156] (Pattern 8) In embodiment 8, the radio waves are linearly polarized, and the first reflector 21, the second reflector 22, and the third reflector 23 are composed of a plurality of linear portions 24 that reflect linearly polarized radio waves.

[0157] According to the above-described embodiment, the deterioration of antenna directivity due to radio wave scattering can be further suppressed.

[0158] (Aspect 9) In embodiment 9, the system includes a compensation unit 30 having a first amplifier 31 for amplifying the radio waves to be transmitted, a second amplifier 32 for amplifying the radio waves to be received, and a switch 33 for switching between a path including the first amplifier 31 and a path including the second amplifier 32, and the reflecting element 20B is located between the compensation unit 30 and the antenna element 12B in the direction of radio wave radiation.

[0159] According to the above-described embodiment, the influence of radio waves from the antenna on the compensation unit 30 can be suppressed.

[0160] (Aspect 10) In embodiment 10, the mobile body 1 is a vehicle having a surrounding confirmation device, and the antenna element 12 is positioned at the end of the surrounding confirmation device.

[0161] The "surroundings confirmation device" corresponds to the "side mirror 3" in the above-described embodiment.

[0162] According to the above embodiment, the directivity range of the antenna 11 can be widened. (Aspect 11) In embodiment 11, the reflective element 20 is positioned in a location that can suppress the scattering of radio waves by the structural part 2.

[0163] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit its interpretation. Furthermore, the present invention may be modified or improved without departing from its spirit, and it goes without saying that the present invention includes equivalents thereof. [Explanation of symbols]

[0164] 1. Mobile object (vehicle) 2. Structural components (vehicle body) 3 Side mirrors 10, 10A~10K Antenna Equipment 12, 12A~12K Antenna Element 20, 20B~20K Reflector 21 1st reflection section 22 2nd reflection section 23 Third reflection section 24 Linear part 30 Compensation Department 31. First Amplifier 32. Second Amplifier 33 switches

Claims

1. An antenna device arranged on a mobile body having a structural part, An antenna element, positioned at a distance from the aforementioned structural part and corresponding to radio waves in a predetermined frequency band, A reflecting element that reflects the aforementioned radio waves, Equipped with, The reflective element is positioned between the structural part and the antenna element in the direction of radiation of the radio waves. The reflective element has a first reflective portion and a second reflective portion. In a top view, in a second direction perpendicular to the first direction in which the antenna element moves away from the structural part, The antenna element is located between the first reflector and the second reflector. Antenna device.

2. The first distance in the second direction between the first reflector and the antenna element, The second distance in the second direction between the second reflector and the antenna element and At least one of them is less than or equal to one-third of the wavelength of the radio wave. The antenna device according to claim 1.

3. At least one of the first distance and the second distance is one-tenth or more and one-fifth or less of the wavelength of the radio wave. The antenna device according to claim 2.

4. The reflective element has a third reflective portion located between the structural portion and the antenna element in the first direction. The antenna device according to claim 1.

5. The third distance in the first direction between the third reflector and the antenna element is one-tenth or more of the wavelength of the radio wave. The antenna device according to claim 4.

6. When the reflective element is viewed in a direction perpendicular to the first and second directions, the first reflective portion, the second reflective portion, and the third reflective portion are connected in a shape. The antenna device according to claim 4.

7. The aforementioned radio waves are linearly polarized, The first reflecting section, the second reflecting section, and the third reflecting section are composed of a plurality of linear sections that reflect the linearly polarized radio waves. The antenna device according to claim 4.

8. A first amplifier that amplifies the radio waves to be transmitted, A second amplifier that amplifies the received radio waves, A switch that switches between the path including the first amplifier and the path including the second amplifier, It has a compensation unit that has, The reflective element is located between the compensation unit and the antenna element in the direction of radiation of the radio waves. The antenna device according to claim 1.

9. The aforementioned moving body is a vehicle equipped with a surrounding confirmation device, The antenna element is positioned at the end of the surrounding area confirmation device. The antenna device according to any one of claims 1 to 8.

10. The reflective element is positioned in a location that can suppress the scattering of radio waves by the structural part. The antenna device according to claim 1.

11. An antenna device arranged on a mobile body having a structural part, An antenna element, positioned at a distance from the aforementioned structural part and corresponding to radio waves in a predetermined frequency band, A reflecting element that reflects the aforementioned radio waves, A first amplifier that amplifies the radio waves to be transmitted, A second amplifier that amplifies the received radio waves, A compensation unit having a switch for switching between a path including the first amplifier and a path including the second amplifier, Equipped with, The reflective element is located between the structural part and the antenna element in the direction of radiation of the radio waves. Antenna device.

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