Arrangement structure of radar device

Abstract

To provide the arrangement structure of a radar device with which it is possible to prevent a decrease in the transmissivity of a radio wave transmitted and received to and from a radar device even when there is a cover member at the front of the radar device.SOLUTION: An arrangement structure 10 of a radar device 3 for transmitting and receiving radio waves includes a cover member 2 located at a position which a transmitted / received radio wave passes through, and a dielectric part 30 located between the cover member 2 and the radar device 3. In a prescribed direction which is the 0° direction in a radiation direction on plane by antennas constituting the radar device 3, a reference length d which is the sum total of an effective length of the dielectric part 30 representing the thickness of the dielectric part 30 that is obtained by reflecting wavelength shortening effect on the basis of the dielectric constant of a material constituting said part, an effective length of the cover member 2 representing the thickness of the cover member 2 that is obtained by reflecting wavelength shortening effect on the basis of the dielectric constant of a material constituting said member, and an interval between the cover member 2 and the dielectric part 30 is set to fall within λ / 2×N±λ / 10, where λ denotes the wavelength of the radio wave and N denotes an integral number.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a layout structure of a radar device. [Background technology]

[0002] Conventionally, there is known a technology in which a radar device is mounted on a moving body such as a vehicle, and the radar device detects the distance to an object within a preset angular range by transmitting and receiving radio waves. For example, Patent Document 1 describes this type of technology.

[0003] Patent Document 1 relates to a radar device including an antenna unit configured to transmit and receive electromagnetic waves, and a cover unit arranged at a position through which the electromagnetic waves transmitted and received by the antenna unit pass. The cover unit in Patent Document 1 has, in order from the antenna unit's closest, a first dielectric layer made of a dielectric material and a second dielectric layer made of a dielectric material having a different dielectric constant from that of the first dielectric layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-211199 Summary of the Invention [Problem to be solved by the invention]

[0005] Radio waves are reflected at the interface between objects made of different materials. Therefore, when a radar device is placed inside a cover member such as a bumper or lens, the radio waves reflect off the cover member, creating standing waves, which can increase loss depending on the distance between the cover member and the radar. Cover members such as bumpers and lenses are designed from the perspective of aesthetics, making it difficult to optimize their physical structure, such as thickness, for radar characteristics. While it is possible to reduce loss by placing a dielectric or adjusting the position of the dielectric, as in conventional technology, unlike free space, the appropriate thickness of cover members and dielectrics varies depending on the material properties (dielectric constant). Conventional technology left room for improvement in terms of improving the transmittance of radar devices.

[0006] An object of the present invention is to provide a radar device arrangement structure that can prevent a decrease in the transmittance of radio waves transmitted and received from the radar device even if a cover member is placed in front of the radar device. [Means for solving the problem]

[0007] The present invention relates to an arrangement structure of a radar device that transmits and receives radio waves, the arrangement structure of the radar device including a cover member that is placed at a position through which the radio waves transmitted and received by the radar device pass, and a dielectric portion that is placed between the cover member and the radar device, wherein, in a predetermined direction that is the 0° direction in a planar radiation direction of an antenna that constitutes the radar device, a reference length that is the sum of a thickness of the dielectric portion, which is an effective length of the dielectric portion obtained by reflecting a wavelength-shortening effect in the thickness based on the dielectric constant of a material that constitutes the dielectric portion, a thickness of the cover member, which is an effective length of the cover member obtained by reflecting a wavelength-shortening effect in the thickness based on the dielectric constant of a material that constitutes the cover member, and a distance between the cover member and the dielectric portion, is set to be in the range of λ / 2×N±λ / 10, where λ is the wavelength of the radio waves and N is an integer.

[0008] The radar device may include a radar section having a radar board equipped with a receiving antenna and a transmitting antenna, and a radome covering the radar board, and the dielectric section may be disposed between the cover member and the radar section.

[0009] The cover member may be a lens, and the dielectric portion may be a concealing structure that covers the radar device so that the radar device is located in a blind spot when viewed from outside the lens.

[0010] The cover member may be the lens and also a light guide.

[0011] The cover member may be a bumper for a moving body, and the dielectric portion may be configured as a part of a bracket that supports the radar device.

[0012] A plurality of the dielectric portions may be arranged in the predetermined direction.

[0013] The reference length can be the sum of the effective length of each of the plurality of dielectric sections, the effective length of the cover member, the distance between the cover member and the dielectric section, and the distance between the plurality of dielectric sections. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a radar device arrangement structure that can prevent a decrease in the transmittance of radio waves transmitted and received from the radar device even if a cover member is provided in front of the radar device. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram of a vehicle to which a radar device arrangement structure according to an embodiment of the present invention is applied; [Figure 2] 1 is a schematic diagram showing an arrangement structure of a radar device according to an embodiment of the present invention; [Figure 3] FIG. 2 is a perspective view showing the positional relationship of the arrangement structure of the radar device according to the present embodiment. [Figure 4]2 is a schematic diagram showing the positional relationship of the arrangement structure of the radar device of the present embodiment as viewed in the left-right direction. FIG. [Figure 5] 5A and 5B are schematic diagrams illustrating an effective length of a cover member of the radar device according to the present embodiment. [Figure 6] FIG. 1 is a schematic diagram showing a simulation configuration for an example and a comparative example. [Figure 7] 10 is a graph showing the relationship between the configuration of a cover member and transmittance in a conventional example. [Figure 8] 10 is a graph showing the relationship between transmittance and reference length in the first embodiment and a conventional example. [Figure 9] 10 is a graph showing the relationship between transmittance and reference length in the second embodiment and the conventional example. [Figure 10] 10 is a graph showing the relationship between transmittance and reference length in the third embodiment and the conventional example. [Figure 11] 10 is a graph showing the relationship between transmittance and reference length in the fourth embodiment and a conventional example. [Figure 12] 10 is a schematic diagram showing the positional relationship of the arrangement structure of the radar device of the first modified example as viewed in the left-right direction. FIG. [Figure 13] 10 is a graph showing the relationship between the reference length and the gain in the arrangement structure of the radar device of the first modified example. [Figure 14] FIG. 10 is a schematic diagram showing the positional relationship of the arrangement structure of the radar device of the second modified example as viewed in the left-right direction. [Figure 15] 10 is a graph showing the relationship between the reference length and the gain in the arrangement structure of the radar device of the second modified example. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0017] FIG. 1 is a schematic diagram of a vehicle 1 to which a layout structure of a radar device 3 according to one embodiment of the present invention is applied.

[0018] The radar device 3 is a millimeter wave radar that transmits radio waves and receives the waves reflected by a target. Information about the target (position, speed, azimuth, etc.) is detected based on the signal received by the radar device 3. In the example of the present embodiment, a total of four radar devices 3 are arranged on the front, rear, left, and right sides of the vehicle 1 as a moving body, but the number of radar devices 3 to be arranged is not limited to this.

[0019] Fig. 2 is a schematic diagram showing an arrangement structure 10 for a radar device 3 according to this embodiment. As shown in Fig. 2, the arrangement structure 10 includes the radar device 3, a bracket 20, a dielectric portion 30, and a cover member 2. In the following description, the 0° direction in the planar radiation direction of the antenna constituting the radar unit 11 (described later) in the radar device 3 is defined as the X direction, the direction perpendicular to the horizontal direction with respect to the X direction is defined as the Y direction, and the direction perpendicular to both the X direction and the Y direction is defined as the Z direction.

[0020] The radar device 3 includes a radar unit 11 that transmits and receives radio waves. Although not shown in Fig. 2 for simplicity, the radar unit 11 mainly consists of a radar board and a radome. The radar board is made up of a transmitting antenna that radiates radio waves and a receiving antenna that receives the reflected waves of the radio waves transmitted by the transmitting antenna. The radome is a cover that covers the front of the radar board and is made of a material that allows the radio waves radiated from the radar board and their reflected waves to pass through.

[0021] The bracket 20 is a support structure that supports the radar device 3 and the dielectric portion 30 inside the cover member 2. The bracket 20 has a radar support portion 21 that supports the radar device 3 and a dielectric support portion 22 that supports the dielectric portion 30. The radar support portion 21 fixes the radar portion 11 of the radar device 3 inside the vehicle 1. The bracket 20 may be fixed to the body side of the vehicle 1 or to the cover member 2 side. The dielectric support portion 22 supports the dielectric portion 30 between the radar device 3 and the cover member 2.

[0022] The dielectric part 30 is disposed between the radar device 3 and the cover member 2. In this embodiment, the dielectric part 30 is configured as a part of the bracket 20. The dielectric part 30 may be configured to be integral with the bracket 20, or may be configured to be connected and fixed to the bracket 20.

[0023] The dielectric portion 30 is made of, for example, a resin with a relative dielectric constant of at least 1. The material of the dielectric portion 30 can be, for example, a thermoplastic resin (polyethylene, polypropylene, polyethylene terephthalate, vinyl chloride, polystyrene, ABS resin, acrylic, polyamide, polycarbonate, tetrafluoroethylene, ethylene acid bicopolymer, etc.) or a thermosetting resin (phenolic resin, melamine resin, unsaturated polyester resin, epoxy resin, etc.).

[0024] Furthermore, the dielectric part 30 is disposed on the outside of the vehicle 1 with respect to the radar device 3, and also functions as a screening structure that hides the radar device 3 from the outside of the vehicle 1.

[0025] The cover member 2 is all or part of the bumper or lamp lens of the vehicle 1. FIG. 1 shows an example in which a radar device 3 is disposed inside the cover member 2. The cover member 2 is made of a material that functions as a second dielectric for the dielectric portion 30. For example, the material for the cover member 2 may be polymethyl methacrylate resin (PMMA) in the case of a lamp lens, or polypropylene (PP) in the case of a bumper. Furthermore, when the cover member 2 is a lamp lens and also a light guide, the material for the cover member 2 may be, for example, acrylic resin (PMMA), polycarbonate resin (PC), or the like. Note that the material for the cover member 2 may be any of the materials exemplified for the dielectric portion 30, other than PMMA or PP.

[0026] Next, the positional relationship of the arrangement structure 10 of the radar device 3 will be described with reference to Figures 3 and 4. Figure 3 is a perspective view showing the positional relationship of the arrangement structure 10 of the radar device 3 of this embodiment. Figure 4 is a schematic diagram showing the positional relationship of the arrangement structure 10 of the radar device 3 of this embodiment as viewed from the left and right. Note that the bracket 20 is omitted from Figures 3 and 4.

[0027] As shown in FIGS. 3 and 4, the radar unit 11 of the radar device 3 is located at the innermost position of the vehicle 1 in the X direction.

[0028] The dielectric part 30 is located outside the vehicle 1 in the X direction relative to the radar part 11 of the radar device 3. The cover member 2 is located outside the vehicle 1 in the X direction relative to the dielectric part 30.

[0029] 4, the position at the antenna center height in the radar unit 11 is defined as the center position P. At the height of the center position P, the sum of the distance between the cover member 2 and the dielectric part 30, the effective length of the dielectric part 30, and the effective length of the cover member 2 is defined as the reference length d. Each element constituting the reference length d will be described below.

[0030] The distance between the cover member 2 and the dielectric part 30 is the distance on a straight line passing through the center position P in the X direction.

[0031] The effective length of the dielectric portion 30 will be described. When a radio wave passes through the dielectric portion 30, a wavelength shortening effect occurs, whereby the wavelength becomes shorter than the wavelength λ in free space. If the relative dielectric constant of the dielectric portion 30 is ε r1 Then, the wavelength λ inside the dielectric part 30 d can be calculated using Equation 1. From Equation 1, the wavelength shortening rate is 1 / √ε r1 Therefore, when the wavelength shortening effect is taken into consideration, the effective length of the dielectric portion 30 in the X direction is calculated by multiplying the thickness of the dielectric portion 30 by √ε r It is assumed that the relative permeability of the dielectric portion 30 is 1. [Number 1] wavelength λ d = wavelength λ0 / √ε r1

[0032] Next, the effective length of the cover member 2 will be described with reference to Figure 5. Figure 5 is a schematic diagram illustrating the effective length of the cover member 2 of the radar device 3 of this embodiment. As shown in Figure 5, the cover member 2 is inclined with respect to the Z direction. Therefore, the radio waves emitted from the radar device 3 are incident at an incident angle θ1 with respect to a direction perpendicular to the surface of the cover member 2 on the vehicle inner side. After entering the boundary surface of the cover member 2 from free space, the radio waves pass through the inside of the cover member 2 at an exit angle θ2. The exit angle θ2 can be calculated using Snell's law shown in Equation 2. [Number 2] N1sinθ1=N2sinθ2 N1: Refractive index of free space N2: refractive index of the dielectric

[0033] The refractive index can be calculated by Equation 3. In Equation 3, unless the material is a ferromagnetic material, the relative permeability can be considered to be 1, and the relative permittivity in the free space outside the cover member 2 can be considered to be 1. Therefore, the path of the cover member 2 has the relative permittivity ε r2 The path length L of the radio wave in the cover member 2 can be calculated based on the thickness of the cover member 2 and the emission angle θ2. Furthermore, since the cover member 2 also has a wavelength shortening effect, the path length L of the cover member 2 is changed by √ε r2 By multiplying this by , the effective length of the cover member 2 is calculated. [Number 3] Refractive index N = (relative permittivity x relative permeability) 1 / 2

[0034] In this embodiment, when the wavelength emitted from the radar device 3 is λ, the configuration of the cover member 2 and the dielectric part 30 and the distance between the cover member 2 and the dielectric part 30 are designed so that the reference length d is N times λ / 2 (N is an integer). By making the reference length d N times λ / 2, it is possible to suppress reflected waves from surrounding structures when the radar device 3 is mounted on the vehicle 1 and to achieve optimal radio wave transmission characteristics.

[0035] Next, the effect of preventing a decrease in the transmittance of radio waves by the arrangement structure 10 of the radar device 3 of this embodiment will be described.

[0036] FIG. 6 is a schematic diagram showing the simulation configurations of an example and a comparative example. FIG. 6(a) shows an arrangement 10a according to one embodiment of the present invention. The arrangement 10a of this example includes a cover member 2a, a dielectric portion 30, and a radar device 3, and the distance in the X direction from the radar device 3 to the cover member 2 is 40 mm. The cover member 2a is disposed parallel to the dielectric portion 30 without tilting in the Z direction. FIG. 6(b) shows an arrangement 110 of a comparative example in which the dielectric portion 30 is omitted from the arrangement 10a.

[0037] First, referring to Fig. 7, the relationship between the material, thickness, and relative dielectric constant of the cover member 2a will be described using an arrangement structure 110 of a comparative example. Fig. 7 is a graph showing the relationship between the configuration of the cover member 2a and transmittance (loss) in a conventional example. Fig. 7 shows a plot of the magnitude of loss versus thickness when the cover member 2a is made of PMMA (relative dielectric constant εr: 3.7) used for lamp lenses, etc., and a plot of the magnitude of loss versus thickness when the cover member 2a is made of PP (relative dielectric constant εr: 2.4) used for bumpers, etc.

[0038] 7, the cover member 2a varies in transmittance depending on the type and thickness of its material. However, the material and thickness of the cover member 2a affect the design of the vehicle 1, and are not necessarily suitable for improving the transmittance of the radar device 3. Therefore, in this embodiment, the transmittance is set to a suitable range by adjusting the dielectric portion 30 and the distance between the dielectric portion 30 and the cover member 2a.

[0039] 8 to 11, we will explain the results of a simulation demonstrating that a decrease in transmittance can be prevented by configuring and arranging the dielectric portion 30 so that the reference length is an integer multiple of λ / 2. In the following simulations, the free-space wavelength λ of radio waves is assumed to be 12.42 mm (λ / 2 is 6.21 mm). In the graphs, the horizontal axis represents the reference length d, which is the sum of the effective length of the cover member 2a, the distance between the cover member 2a and the dielectric portion 30, and the effective length of the dielectric portion 30, divided by the free-space wavelength λ of the radio waves (d / λ). The vertical axis represents the loss (dB) during radio wave transmission. For example, if the effective length of the material of the cover member 2a is 1.04 mm and the effective length of the dielectric portion 30 is 1.73 mm, and the distance between the cover member 2a and the dielectric portion 30 is 15 mm, the reference length d is 17.77 mm, calculated by adding the effective length of the cover member 2a and the effective length of the dielectric portion 30. Dividing this reference length d by λ (12.42) gives 1.43.

[0040] Fig. 8 is a graph showing the relationship between transmittance and reference length in the first embodiment and the conventional example. Fig. 8 shows the simulation results for the dielectric portion 30 when its thickness is 3 mm and the relative dielectric constant of the material is 3. It is assumed that the effective length of the material of the cover member 2a is 1.04 mm and the effective length of the dielectric portion 30 is 1.73 mm.

[0041] In the example of FIG. 8, the loss of the conventional arrangement 110 without the dielectric portion 30 is shown as −1.5 dB (dashed line in the figure), and the relationship between the loss of the dielectric portion 30 and the reference length d of the example is also shown. In this example, the ranges of d / λ corresponding to the range where the loss is smaller than the −1.5 dB loss of the conventional arrangement without the dielectric portion 30 are (1.43 to 1.59), (1.91 to 2.07), and (2.44 to 2.48). Because the integer part of twice d / λ is a numerical value that is an integer multiple, the range of good transmittance roughly corresponds to the range where the reference length is an integer multiple of λ / 2 ±λ / 10. In the example of FIG. 8, for example, when N=3, N times λ / 2 is 18.63 mm, and the range where the loss is smaller than the conventional arrangement is 17.35 to 19.85 mm, which is roughly within the range of ±λ / 10.

[0042] Fig. 9 is a graph showing the relationship between transmittance and reference length in the second embodiment and the conventional example. Fig. 9 shows the simulation results for the dielectric portion 30 when its thickness is 4 mm and the relative dielectric constant of the material is 3. The effective length of the material of the cover member 2a is 1.04 mm, and the effective length of the dielectric portion 30 is 2.31 mm.

[0043] 9, the ranges of d / λ corresponding to the range where the loss is smaller than the loss of -1.5 dB of the conventional example where the dielectric section 30 is not arranged are (1.40 to 1.60), (1.92 to 2.08), and (2.40 to 2.52). Because the integer part of twice d / λ is a numerical value that is an integer multiple, the range of good transmittance where the loss is smaller than the loss of -1.5 dB of the conventional example where the dielectric section 30 is not arranged roughly corresponds to the range where the reference length is an integer multiple of λ / 2 ±λ / 10.

[0044] Fig. 10 is a graph showing the relationship between transmittance and reference length in the third embodiment and the conventional example. Fig. 10 shows the simulation results for the dielectric portion 30 when its thickness is 3 mm and the relative dielectric constant of the material is 4. The effective length of the material of the cover member 2a is 1.04 mm, and the effective length of the dielectric portion 30 is 1.50 mm.

[0045] 10, the ranges of d / λ corresponding to the range where the loss is smaller than the loss of -1.5 dB of the conventional example where the dielectric section 30 is not arranged are (1.41 to 1.61), (1.94 to 2.14), and (2.42 to 2.46). Because the integer part of twice d / λ is a numerical value that is an integer multiple, the range of good transmittance where the loss is smaller than the loss of -1.5 dB of the conventional example where the dielectric section 30 is not arranged roughly corresponds to the range where the reference length is an integer multiple of λ / 2 ±λ / 10.

[0046] Fig. 11 is a graph showing the relationship between transmittance and reference length in the fourth embodiment and the conventional example. Fig. 11 shows the simulation results for the dielectric portion 30 when its thickness is 4 mm and the relative dielectric constant of the material is 4. The effective length of the material of the cover member 2a is 1.04 mm, and the effective length of the dielectric portion 30 is 2.00 mm.

[0047] 11, the ranges of d / λ corresponding to the range where the loss is smaller than the loss of -1.5 dB of the conventional example where the dielectric section 30 is not arranged are (1.45 to 1.57), (1.94 to 2.06), and (2.46 to 2.50). Because the integer part of twice d / λ is a numerical value that is an integer multiple, the range of good transmittance where the loss is smaller than the loss of -1.5 dB of the conventional example where the dielectric section 30 is not arranged roughly corresponds to the range where the reference length is an integer multiple of λ / 2 ±λ / 10.

[0048] As described above, the arrangement structure 10 of the radar device 3 that transmits and receives radio waves includes the cover member 2 (cover member 2a) that is placed at a position where the radio waves transmitted and received by the radar device 3 pass through, and the dielectric portion 30 that is placed between the cover member 2 and the radar device 3, and in a predetermined direction that is a direction perpendicular to the radio wave transmission and reception surface of the radar device 3, the reference length that is the sum of the thickness of the dielectric portion, which is the effective length of the dielectric portion obtained by reflecting the wavelength shortening effect in the thickness based on the dielectric constant of the material that constitutes the dielectric portion, the thickness of the cover member, which is the effective length of the cover member obtained by reflecting the wavelength shortening effect in the thickness based on the dielectric constant of the material that constitutes the cover member, and the distance between the cover member and the dielectric portion is set to be in the range of λ / 2×N±λ / 10, where λ is the wavelength of the radio waves and N is an integer.

[0049] As a result, even if the shape and thickness of the cover member 2 cannot be changed due to restrictions on appearance or the like, it is possible to prevent a decrease in radio wave transmittance by adjusting the material (relative dielectric constant), thickness, and positional relationship of the dielectric portion 30 with respect to the cover member 2 so that the reference length d falls within the range of λ / 2×N±λ / 10. In other words, the material of the dielectric portion 30, the thickness of the dielectric portion 30, the spacing between the dielectric portion 30 and the cover member 2, etc. can be set depending on the shape of the cover member 2.

[0050] In addition, the radar device 3 of this embodiment includes a radar board having a receiving antenna and a transmitting antenna, and a radar section 11 having a radome covering the radar board, and the dielectric section 30 is arranged between the cover member 2 and the radar section 11.

[0051] This allows the dielectric part 30 to be disposed in the space between the radar part 11 and the cover member 2 outside the radar part 11 .

[0052] Furthermore, the cover member 2 of this embodiment is a lens, and the dielectric part 30 can be a blind structure that covers the radar device 3 so that the radar device 3 is located in a blind spot when viewed from outside the lens.

[0053] This makes it possible to prevent the radar device 3 from being visible from the outside when the radar device 3 is mounted inside the lamp, thereby realizing a configuration that prevents a decrease in transmittance without impairing the design.

[0054] Furthermore, the cover member 2 of this embodiment can also be configured as a lens and a light guide.

[0055] As a result, even when the cover member 2 is made of a light guide, a decrease in the transmittance of radio waves can be prevented by adjusting the material and position of the dielectric part 30 according to the material of the light guide so that the reference length d falls within the range of λ / 2×N±λ / 10.

[0056] Moreover, the cover member 2 of this embodiment may be a bumper of a vehicle 1 as a moving body, and the dielectric part 30 may be configured as a part of a bracket 20 that supports the radar device 3.

[0057] This allows the dielectric part 30 to be fixed at an appropriate position by utilizing the bracket 20 that supports the radar device 3, without the need to prepare a separate structure for supporting the dielectric part 30.

[0058] In the above embodiment, an example in which one dielectric part 30 is arranged between the cover member 2 (cover member 2a) and the radar device 3 has been described, but the embodiment of the present invention is not limited to this configuration. Next, a modified example in which the configuration of the dielectric part 30 is different will be described. In the following description, configurations that are common or similar to those in the above embodiment may be assigned the same reference numerals and detailed description thereof may be omitted.

[0059] 12 is a schematic diagram showing the positional relationship of the arrangement structure 10b of the radar device 3 of the first modified example as viewed in the Y direction. As shown in FIG. 12, the arrangement structure 10b of the radar device 3 includes a plurality of dielectric portions 30a and 30b between the cover member 2 and the radar device 3. The dielectric portion 30a is located on the cover member 2 side, and the dielectric portion 30b is located on the radar device 3 side. The method of calculating the effective lengths of the dielectric portions 30a and 30b is the same as in the above embodiment. The cover member 2 of the first modified example is the same as the cover member 2 described with reference to FIG. 4, and is configured to be inclined with respect to the Z-axis direction.

[0060] The reference length da is the sum of the effective length of each of the plurality of dielectric portions 30a and 30b, the effective length reflecting the wavelength shortening effect based on the dielectric constant of the cover member 2, the spacing between the cover member 2 and the dielectric portion 30a, and the spacing between the plurality of dielectric portions 30a and 30b. The material and position of each of the dielectric portions 30a and 30b are adjusted so that this reference length da falls within the range of ±λ / 10 of the wavelength λ / 2 of the radio wave times an integer multiple. Note that the material (dielectric constant), thickness, and position of the dielectric portion 30a may be fixed, and the reference length da may be adjusted by changing the material (dielectric constant), thickness, and position of the dielectric portion 30b.

[0061] Fig. 13 is a graph showing the relationship between the reference length da and gain in the arrangement structure 10b of the radar device 3 of the first modified example. In the graph of Fig. 13, the horizontal axis represents the reference length da, and the vertical axis represents the gain. The gain of the conventional arrangement structure in which the dielectric parts 30a and 30b are not arranged is also shown by a dashed line. As shown in Fig. 13, by configuring the arrangement structure 10b of the radar device 3 so that the reference length da falls within the range of ±λ / 10 of the wavelength λ / 2 of the radio wave times an integer multiple, a gain higher than the gain of the conventional arrangement structure (approximately 8.5 dB) can be achieved.

[0062] Fig. 14 is a schematic diagram showing the positional relationship of the radar device arrangement structure of the second modified example as viewed in the Y direction. As shown in Fig. 14, the arrangement structure 10c of the radar device 3 includes a plurality of dielectric portions 30a and 30b between the cover member 2a and the radar device 3. The configurations of the dielectric portions 30a and 30b are the same as those of the first modified example, and the calculation of the effective length db is also the same as in the above embodiment. Furthermore, the cover member 2 in the second modified example is the same as the cover member 2a described with reference to Fig. 6(a), and the positional relationship between the cover member 2a and the dielectric portion 30 is parallel.

[0063] The reference length db is the sum of the effective length of each of the plurality of dielectric portions 30a and 30b, the effective length reflecting the wavelength shortening effect based on the dielectric constant of the cover member 2a, the spacing between the cover member 2 and the dielectric portion 30a, and the spacing between the plurality of dielectric portions 30a and 30b. The material and position of each of the dielectric portions 30a and 30b are adjusted so that this reference length db falls within the range of ±λ / 10 of the wavelength λ / 2 × an integer multiple of the radio wave. Note that the material (dielectric constant), thickness, and position of the dielectric portion 30a may be fixed, and the reference length db may be adjusted by changing the material (dielectric constant), thickness, and position of the dielectric portion 30b.

[0064] Fig. 15 is a graph showing the relationship between the reference length db and gain in the arrangement structure 10c of the radar device 3 of the second modified example. In the graph of Fig. 15, the horizontal axis represents the reference length db, and the vertical axis represents the gain. The gain of the conventional arrangement structure in which the dielectric parts 30a and 30b are not arranged is shown by a dashed line. As shown in Fig. 15, by configuring the arrangement structure 10c of the radar device 3 so that the reference length db falls within the range of ±λ / 10 of the wavelength λ / 2 of the radio wave times an integer multiple, a gain higher than that of the conventional arrangement structure shown by the dashed line can be achieved.

[0065] As described above, a plurality of the dielectric portions 30a and 30b of the modified example are arranged in a predetermined direction (X direction).

[0066] This allows the use of a plurality of dielectric portions 30a and 30b, thereby increasing the options for material selection and arrangement options.

[0067] The reference length db can be the sum of the effective length of each of the multiple dielectric portions 30a, 30b, the effective length reflecting the wavelength shortening effect based on the relative dielectric constant of the cover members 2, 2a, the distance between the cover members 2, 2a and the dielectric portion 30a, and the distance between the multiple dielectric portions 30a, 30b.

[0068] This makes it possible to determine the placement so as to specifically prevent a decrease in radio wave transmittance.

[0069] Although the embodiments and modifications of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be modified as appropriate. For example, the present invention can be widely applied to radar devices 3 installed in various mobile objects, including the vehicle 1 such as the four-wheeled automobile exemplified in the embodiments, or in facilities where it is difficult to optimize the radio wave transparency of the radar device 3 due to requirements such as appearance and design. [Explanation of symbols]

[0070] 1 vehicle 2, 2a Cover member 3. Radar equipment 10, 10a~10c arrangement structure 11 Radar section 20 Bracket 30, 30a, 30b Dielectric part

Claims

1. An arrangement structure of a radar device that transmits and receives radio waves, a cover member disposed at a position through which the radio waves transmitted and received by the radar device pass; a dielectric portion disposed between the cover member and the radar device; Including, In a predetermined direction that is a 0° direction in a plane radiation direction of an antenna constituting the radar device, a thickness of the dielectric portion, which is an effective length of the dielectric portion obtained by reflecting a wavelength shortening effect in the thickness based on the relative dielectric constant of a material constituting the dielectric portion; and a thickness of the cover member, which is an effective length of the cover member obtained by reflecting a wavelength shortening effect in the thickness based on the relative dielectric constant of a material constituting the cover member; and a gap between the cover member and the dielectric portion; The reference length, which is the sum of the above, is set to be in the range of λ / 2×N±λ / 10, where λ is the wavelength of the radio wave and N is an integer. Radar equipment layout structure.

2. The radar device a radar substrate having a receiving antenna and a transmitting antenna; a radome covering the radar substrate, The dielectric portion is disposed between the cover member and the radar unit; The radar device arrangement structure according to claim 1 .

3. the cover member is a lens, the dielectric portion is a blind structure that covers the radar device so that the radar device is located in a blind spot when viewed from outside the lens.

3. The radar device arrangement structure according to claim 1 or 2.

4. The cover member is the lens and also a light guide. The radar device arrangement structure according to claim 3 .

5. the cover member is a bumper of a moving body, The dielectric portion is configured as a part of a bracket that supports the radar device.

3. The radar device arrangement structure according to claim 1 or 2.

6. a plurality of the dielectric portions are arranged in the predetermined direction; 3. The radar device arrangement structure according to claim 1 or 2.

7. The reference length is an effective length of each of the plurality of dielectric portions; the effective length of the cover member; a gap between the cover member and the dielectric portion; Spacing between the plurality of dielectric portions; is the sum of 7. The radar device arrangement structure according to claim 6.

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