Radome for automotive radar device and automotive radar structure

Abstract

To provide a radome which exhibits practical snow melting capability as a radome for a vehicle-mounted radar device while suppressing attenuation of an electromagnetic wave emitted by the vehicle-mounted radar device within an acceptable range.SOLUTION: A radome 1 for a vehicle-mounted radar device is provided, having a base body 2 comprising an electromagnetic wave transparent base material 3 and a heater wire 41 stacked on an inner surface of the base material 3 and wired along an in-plane direction of the base material 3. Linear portions 411 of the heater wire 41 are juxtaposed in a spaced-apart manner in the in-plane direction of the base material 3 within an electromagnetic wave irradiated area R of the base material 3. The linear portions 411 of the heater wire 41 in the electromagnetic wave radiated area R of the base material 3 is set to occupy area corresponding to 1-24%, inclusive, of the electromagnetic wave irradiated area R.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a radome for an on-vehicle radar device that is provided on the front side of the on-vehicle radar device, and more particularly to a radome for an on-vehicle radar device that has a snow-melting function and an on-vehicle radar structure that includes this radome. [Background technology]

[0002] Conventional radomes for automotive radar devices with snow-melting capabilities include those described in Patent Documents 1 and 2, which are capable of suppressing attenuation of millimeter waves as they pass through while still providing the snow-melting function. These radomes include a decorative main body that is millimeter-wave transparent and a linear heater wire. The heater wire has multiple straight sections that run parallel to each other, with the ends of adjacent straight sections connected by arc-shaped folded sections. Some of the straight sections of the heater wire are located within the millimeter-wave irradiation area, and the area ratio of all straight sections within the millimeter-wave irradiation area is set to 10% or less, so that the millimeter-wave attenuation is within the allowable value of 2.5 dB.

[0003] Furthermore, Patent Documents 1 and 2 disclose that when the straight portion of the heater wire is parallel to the polarization plane of the millimeter wave, the millimeter wave may come into surface contact with the straight portion of the heater wire, hindering transmission and attenuating the millimeter wave, and that by arranging the straight portion of the heater wire perpendicular to the polarization plane of the millimeter wave, the area where the millimeter wave comes into contact with the straight portion of the heater wire can be minimized, minimizing the amount of millimeter wave whose transmission is hindered and minimizing the amount of attenuation of the millimeter wave. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-66705 [Patent Document 2] Japanese Patent Application Publication No. 2018-66706 Summary of the Invention [Problem to be solved by the invention]

[0005] In the radomes of Patent Documents 1 and 2, it is possible to suppress the attenuation of millimeter waves by setting the area ratio of the straight portion of the heater wire to the millimeter-wave irradiation region to 10% or less. However, the amount of heater wire required to achieve a practical snow-melting function in a radome for an automotive radar device is not specified. Therefore, if the area ratio of the straight portion of the heater wire to the millimeter-wave irradiation region is set to an arbitrary area ratio of 10% or less, it may not be possible to achieve a practical snow-melting function. Therefore, there is a demand for a radome with a structure that can suppress the attenuation of the electromagnetic waves emitted by an automotive radar device while achieving a practical snow-melting function in a radome for an automotive radar device.

[0006] The present invention has been proposed in view of the above-mentioned problems, and aims to provide a radome for an on-board radar device and an on-board radar structure that can suppress the attenuation of the electromagnetic waves emitted by the on-board radar device within an acceptable range while exhibiting a practical snow-melting function as a radome for an on-board radar device. [Means for solving the problem]

[0007] The radome for an automotive radar device of the present invention comprises an electromagnetic wave transparent substrate and a base body having heater wires laminated on the inner surface of the substrate and wired in the surface direction of the substrate, wherein straight portions of the heater wires are arranged in parallel with intervals in the surface direction of the substrate in the electromagnetic wave irradiation area of ​​the substrate, and the surface occupancy rate of the straight portions of the heater wires in the electromagnetic wave irradiation area of ​​the substrate is set to be 1% or more and 24% or less. and a radome for an on-vehicle radar device of the present invention includes an electromagnetic wave-transmitting substrate and a base body including heater wires laminated and arranged on an inner surface of the substrate, the inner surface being on the center side of the vehicle, in front of the on-vehicle radar device disposed on the center side of the vehicle, and wired in a surface direction of the substrate, wherein straight portions of the heater wires are arranged in parallel with intervals in the surface direction of the substrate in an electromagnetic wave irradiation region of the substrate, the straight portions of the heater wires are arranged in parallel so as to extend approximately perpendicular to the polarization plane of the linearly polarized electromagnetic waves irradiated by the on-vehicle radar device, and the surface occupancy rate of the straight portions of the heater wires in the electromagnetic wave irradiation region of the substrate is set to be 1% or more and 24% or less, the heater wire and an electromagnetic wave-transmitting insulating film form a heater sheet, the heater sheet is laminated and fixed on the inner surface of the substrate, a refractive index defined based on the complex dielectric constant of the substrate and a refractive index defined based on the complex dielectric constant of the insulating film are matched or close to each other, and the insulating film is fixed to the substrate by welding the surface of the insulating film facing the substrate.The radome for an on-vehicle radar device of the present invention includes an electromagnetic wave transparent substrate and a base body including heater wires arranged on an inner surface of the substrate on the vehicle center side, which is in front of the on-vehicle radar device arranged on the vehicle center side, and wired in a surface direction of the substrate, wherein linear portions of the heater wires are arranged in parallel with intervals in the surface direction of the substrate in an electromagnetic wave irradiation region of the substrate, the linear portions of the heater wires are arranged in parallel with intervals in the surface direction of the substrate, and extend substantially perpendicularly to the polarization plane of the linearly polarized electromagnetic waves irradiated by the on-vehicle radar device, and the surface occupancy rate of the linear portions of the heater wires in the electromagnetic wave irradiation region of the substrate is The dielectric constant is set to be 1% or more and 24% or less, the heater sheet is composed of the heater wire and an electromagnetic wave transparent insulating film, the heater sheet is laminated and fixed to the inner surface side of the base material to wire the heater wire, the refractive index defined based on the complex dielectric constant of the base material and the refractive index defined based on the complex dielectric constant of the insulating film match or are close to each other, and the insulating film is fixed to the base material via an adhesive layer whose refractive indexes defined based on the complex dielectric constant of the base material and the insulating film match or are close to each other. According to this, by setting the surface occupancy rate of the straight portions of the heater wire in the electromagnetic wave irradiation area of ​​the substrate to 1% or more, the temperature of the outer surface of the substrate can be kept above 0°C even when the ambient temperature is -5°C and the vehicle is traveling at a speed of 100 km / h. Therefore, the attenuation of the electromagnetic waves emitted by the automotive radar device can be suppressed within the required allowable range, and the radome for the automotive radar device can exhibit a practical snow-melting function.

[0008] The radome for an automotive radar device of the present invention is characterized in that the straight portions of the heater wire are arranged in parallel so as to extend approximately perpendicular to the polarization plane of the linearly polarized electromagnetic wave irradiated by the automotive radar device, and the surface occupancy rate of the straight portions of the heater wire in the electromagnetic wave irradiation area of ​​the substrate is set to be 1% or more and 24% or less. This allows the radome for an on-board radar device to exhibit practical snow-melting functions, while also ensuring that the transmittance of the base material to the electromagnetic waves emitted by the on-board radar device is -1.5 dB or higher, thereby suppressing the attenuation of electromagnetic waves within a high, practically sufficient allowable range.

[0009] The radome for an automotive radar device of the present invention is characterized in that the straight portions of the heater wire are arranged in parallel so as to extend approximately perpendicular to the polarization plane of the linearly polarized electromagnetic wave irradiated by the automotive radar device, and the surface occupancy rate of the straight portions of the heater wire in the electromagnetic wave irradiation area of ​​the substrate is set to be 3% or more and 20% or less. This allows the temperature of the outer surface of the base material to exceed 0°C even when the vehicle is traveling at 100 km / h at an ambient temperature of -15°C, ensuring reliable snow melting for the radome for the automotive radar device even in harsh cold environments. It also ensures that the transmittance of the base material for the electromagnetic waves emitted by the automotive radar device is -1.0 dB or higher, suppressing the attenuation of the electromagnetic waves within a very high allowable range that is sufficient for practical use. Furthermore, the straight portions of the heater wires are arranged in parallel so that they extend approximately perpendicular to the polarization plane of the linearly polarized electromagnetic waves irradiated by the on-vehicle radar device, and the surface occupancy rate of the straight portions of the heater wires in the electromagnetic wave irradiation area of ​​the substrate is set to 1% or more and 20% or less.Furthermore, the straight portions of the heater wires are arranged in parallel so that they extend approximately perpendicular to the polarization plane of the linearly polarized electromagnetic waves irradiated by the on-vehicle radar device, and the surface occupancy rate of the straight portions of the heater wires in the electromagnetic wave irradiation area of ​​the substrate is set to 3% or more and 24% or less.

[0010] The radome for an automotive radar device of the present invention is characterized in that the straight portions of the heater wire are arranged in parallel so as to extend approximately perpendicular to the polarization plane of the linearly polarized electromagnetic wave irradiated by the automotive radar device, and the surface occupancy rate of the straight portions of the heater wire in the electromagnetic wave irradiation area of ​​the substrate is set to be 3% or more and 7.5% or less. This allows the temperature of the outer surface of the base material to exceed 0°C even when the vehicle is traveling at 100 km / h at an ambient temperature of -15°C, ensuring reliable snow melting on the radome for the automotive radar device even in harsh cold environments. Furthermore, the transmittance of the base material to the electromagnetic waves emitted by the automotive radar device can be guaranteed to be -0.35 dB or higher, ensuring extremely high electromagnetic wave transmittance.

[0011] The radome for an automotive radar device of the present invention is characterized in that the straight portions of the heater wire are arranged in parallel so as to extend approximately parallel to the polarization plane of the linearly polarized electromagnetic wave irradiated by the automotive radar device, and the surface occupancy rate of the straight portions of the heater wire in the electromagnetic wave irradiation area of ​​the substrate is set to be 1% or more and 16% or less. Furthermore, the radome for an on-vehicle radar device of the present invention comprises an electromagnetic wave-transmitting substrate, and a base body including heater wires laminated and arranged on the inner surface of the substrate, which is on the center side of the vehicle and in front of the on-vehicle radar device arranged on the center side of the vehicle, and wired in a surface direction of the substrate, wherein straight portions of the heater wires are arranged in parallel with intervals in the surface direction of the substrate in an electromagnetic wave irradiation region of the substrate, the straight portions of the heater wires are arranged in parallel so as to extend approximately parallel to the polarization plane of the linearly polarized electromagnetic waves irradiated by the on-vehicle radar device, and the surface occupancy rate of the straight portions of the heater wires in the electromagnetic wave irradiation region of the substrate is set to be 1% or more and 16% or less, the heater wire and an electromagnetic wave-transmitting insulating film form a heater sheet, the heater sheet is laminated and fixed on the inner surface of the substrate, the refractive index defined based on the complex dielectric constant of the substrate and the refractive index defined based on the complex dielectric constant of the insulating film are matched or close to each other, and the insulating film is fixed to the substrate by welding the surface of the insulating film facing the substrate.The radome for an on-vehicle radar device of the present invention includes an electromagnetic wave transparent substrate and a base body including heater wires arranged on an inner surface of the substrate on the vehicle center side, which is in front of the on-vehicle radar device arranged on the vehicle center side, and wired in a surface direction of the substrate, wherein linear portions of the heater wires are arranged in parallel with intervals in the surface direction of the substrate in an electromagnetic wave irradiation region of the substrate, the linear portions of the heater wires are arranged in parallel with each other so as to extend approximately parallel to the polarization plane of the linearly polarized electromagnetic wave irradiated by the on-vehicle radar device, and the surface occupancy rate of the linear portions of the heater wires in the electromagnetic wave irradiation region of the substrate is 1 % or more and 16% or less, a heater sheet is constituted by the heater wire and an electromagnetic wave transparent insulating film, the heater sheet is laminated and fixed to the inner surface side of the base material to wire the heater wire, a refractive index defined based on the complex dielectric constant of the base material and a refractive index defined based on the complex dielectric constant of the insulating film match or are close to each other, and the insulating film is fixed to the base material via an adhesive layer whose refractive indexes defined based on the complex dielectric constant of the base material and the insulating film match or are close to each other. This allows the radome for an on-board radar device to exhibit practical snow-melting functions, while also ensuring that the transmittance of the base material to the electromagnetic waves emitted by the on-board radar device is -1.5 dB or higher, thereby suppressing the attenuation of electromagnetic waves within a high, practically sufficient allowable range.

[0012] The radome for an automotive radar device of the present invention is characterized in that the straight portions of the heater wire are arranged in parallel so as to extend approximately parallel to the polarization plane of the linearly polarized electromagnetic wave irradiated by the automotive radar device, and the surface occupancy rate of the straight portions of the heater wire in the electromagnetic wave irradiation area of ​​the substrate is set to be 3% or more and 13% or less. This allows the temperature of the outer surface of the base material to exceed 0°C even when the vehicle is traveling at 100 km / h at an ambient temperature of -15°C, ensuring reliable snow melting for the radome for the automotive radar device even in harsh cold environments. It also ensures that the transmittance of the base material for the electromagnetic waves emitted by the automotive radar device is -1.0 dB or higher, suppressing the attenuation of the electromagnetic waves within a very high allowable range that is sufficient for practical use. Furthermore, the straight portions of the heater wires are arranged in parallel so that they extend approximately parallel to the polarization plane of the linearly polarized electromagnetic waves irradiated by the on-vehicle radar device, and the surface occupancy rate of the straight portions of the heater wires in the electromagnetic wave irradiation area of ​​the substrate is set to 1% or more and 13% or less.Furthermore, the straight portions of the heater wires are arranged in parallel so that they extend approximately parallel to the polarization plane of the linearly polarized electromagnetic waves irradiated by the on-vehicle radar device, and the surface occupancy rate of the straight portions of the heater wires in the electromagnetic wave irradiation area of ​​the substrate is set to 3% or more and 16% or less.

[0013] The radome for an automotive radar device of the present invention is characterized in that the heater wire is wired in a meandering manner with folded back portions, the directions of currents flowing in adjacent straight portions of the heater wire are approximately anti-parallel to each other, and at least four straight portions of the heater wire are arranged side by side at similar pitches in the electromagnetic wave irradiation area of ​​the substrate. This allows the directions of currents flowing through the straight portions of adjacent heater wires to be antiparallel to each other, making the electromagnetic waves radiated from adjacent heater wires out of phase and canceling out the electromagnetic radiation from the heater wires, resulting in better electromagnetic wave transmission performance. Furthermore, by arranging at least four heater wires in parallel at a pitch that approximates the straight portions of the heater wires in the electromagnetic wave irradiation area of ​​the substrate, the temperature distribution throughout the electromagnetic wave irradiation area of ​​the substrate can be more evened out, preventing the occurrence of localized areas with low temperatures when the heater wires are heated, and ensuring more reliable snow melting throughout the entire electromagnetic wave irradiation area of ​​the substrate.

[0014] The radome for an on-vehicle radar device of the present invention is characterized in that the heater wire is wired in a meandering manner with folded back turns, the directions of currents flowing in adjacent straight portions of the heater wire are approximately anti-parallel to each other, the straight portions of the heater wire within the electromagnetic wave irradiation area and the straight portions of the heater wire outside the electromagnetic wave irradiation area adjacent to each other are arranged at a pitch similar to the pitch between the straight portions of the heater wire within the electromagnetic wave irradiation area, and the straight portions of the heater wire outside the electromagnetic wave irradiation area are extended for a length equal to or longer than the length within the electromagnetic wave irradiation area of ​​the straight portions of the heater wire in the adjacent electromagnetic wave irradiation area. According to this, the directions of currents flowing through adjacent straight portions of the heater wire are made antiparallel to each other, so that the electromagnetic waves radiated from the adjacent heater wires have opposite phases, thereby canceling out the electromagnetic radiation from the heater wires and obtaining better electromagnetic wave transmission performance. Also, by arranging the straight portions of the heater wire outside the electromagnetic wave irradiation region adjacent to the straight portions of the heater wire within the electromagnetic wave irradiation region at a pitch similar to the pitch between the straight portions of the heater wire within the electromagnetic wave irradiation region, and extending the straight portions of the heater wire outside the electromagnetic wave irradiation region by a length equal to or longer than the length within the electromagnetic wave irradiation region of the straight portions of the heater wire within the adjacent electromagnetic wave irradiation region, it is possible to cancel out the electromagnetic radiation from the straight portions of the heater wire within the electromagnetic wave irradiation region located near the periphery of the electromagnetic wave irradiation region with high certainty, regardless of whether the number of straight portions juxtaposed within the electromagnetic wave irradiation region is even or odd, thereby obtaining even better electromagnetic wave transmission performance.

[0015] The in-vehicle radar structure of the present invention is characterized by comprising the in-vehicle radar device radome of the present invention and an in-vehicle radar device that irradiates the in-vehicle radar device radome with linearly polarized electromagnetic waves. This makes it possible to obtain an on-vehicle radar structure that exhibits the effects of the on-vehicle radar device radome of the present invention. [Effects of the Invention]

[0016] According to the present invention, the attenuation of the electromagnetic waves emitted by the vehicle-mounted radar device can be suppressed to within an acceptable range, while the radome for the vehicle-mounted radar device can exhibit a practical snow-melting function. [Brief explanation of the drawings]

[0017] [Figure 1] 1A is a front view of a radome for an on-vehicle radar device according to an embodiment of the present invention, and FIG. 1B is a partially enlarged view of FIG. 1A. [Figure 2] Enlarged cross-sectional view of Figure 1 taken along line AA. [Figure 3] Enlarged cross-sectional view of FIG. 1 at B-B. [Figure 4] 1 is an explanatory diagram of an on-vehicle radar structure including a radome for an on-vehicle radar device according to an embodiment; [Figure 5] FIG. 10 is a cross-sectional view illustrating a modified example of the radome for the vehicle-mounted radar device according to the embodiment. [Figure 6] FIG. 10 is a schematic diagram of a measuring device for an example experiment in which the relationship between the surface occupancy of a heater wire in an electromagnetic wave irradiation area and the electromagnetic wave transmittance is measured. [Figure 7] (a) is a schematic diagram illustrating the state in which an electromagnetic wave is irradiated onto a sample used in an experimental example, with the polarization plane of the linearly polarized wave perpendicular to the straight part of the heater wire of the sample; (b) is a schematic diagram illustrating the state in which an electromagnetic wave is irradiated onto a sample, with the polarization plane of the linearly polarized wave parallel to the straight part of the heater wire of the sample used in an experimental example. [Figure 8] 10 is a graph of an experimental example showing the relationship between the surface occupancy of the heater wire and the electromagnetic wave transmittance when the polarization plane of the linearly polarized electromagnetic wave is irradiated onto a sample perpendicular to the straight part of the heater wire and when the polarization plane is parallel to the straight part of the heater wire. [Figure 9] 10 is a graph showing an example experiment showing the relationship between the surface occupancy of the heater wire and the outer surface temperature of the sample when the ambient temperature is -5°C and when the ambient temperature is -15°C. [Figure 10] 10 is a graph of an experimental example showing the relationship between the surface occupancy of the heater wire, the electromagnetic wave transmittance, and the outer surface temperature of a sample when the sample is irradiated with linearly polarized electromagnetic waves with the polarization plane perpendicular to the straight portion of the heater wire. [Figure 11] 10 is a graph of an experimental example showing the relationship between the surface occupancy of the heater wire, the electromagnetic wave transmittance, and the outer surface temperature of a sample when the polarization plane of linearly polarized electromagnetic waves is parallel to the straight portion of the heater wire and the sample is irradiated with the linearly polarized electromagnetic waves. DETAILED DESCRIPTION OF THE INVENTION

[0018] [Radome for vehicle-mounted radar device according to embodiment] 1 to 3, a radome 1 for an on-vehicle radar device according to an embodiment of the present invention is composed of an electromagnetic wave transparent substrate 3 and a base 2 including a heater wire 41 laminated on the inner surface of the substrate 3, in other words, on the center side of the vehicle, and wired in the surface direction of the substrate 3. The substrate 3 can be made of any appropriate material within the scope of the present invention, such as synthetic resin, glass, or ceramics, but is preferably made of insulating synthetic resin.

[0019] The radome 1 in the illustrated example is a bumper cover attached to a vehicle bumper, and the base material 3 is formed of an insulating synthetic resin. When the base material 3 is made of an insulating synthetic resin, the material may be any appropriate material within an applicable range, and examples thereof include acrylic resins such as acrylonitrile-butadiene-styrene copolymer (ABS), polypropylene (PP), and polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET), polyethylene (PE), acrylonitrile-styrene copolymer (AS), polystyrene (PS), cycloolefin polymer (COP), acrylonitrile-styrene-acrylate copolymer (ASA), and acrylonitrile-ethylenepropyl rubber-styrene copolymer (AES), either alone or in combination of two or more thereof, and may also contain additives.

[0020] In this embodiment, the heater wire 41 constitutes part of the heater sheet 4, which is composed of the heater wire 41 and an electromagnetically transparent insulating film 42. In the illustrated example, the heater wire 41 is embedded entirely within the planar insulating film 42 or embedded so as to be exposed on the rear side of the planar insulating film 42. The heater wire 41 can be made of any suitable conductive material, such as nichrome wire, iron chromium, copper, silver, carbon fiber, or a transparent conductive film such as an ITO film. The insulating film 42 can be made of any suitable insulating material with electromagnetic wave transparency, and is preferably made of an insulating synthetic resin such as polycarbonate (PC), polyethylene (PE), polypropylene (PP, OPP), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyvinyl chloride (PVC), polystyrene (PS), acrylic (AC), or polyether ether ketone (PEEK).

[0021] In addition, the heater sheet 4 can have any other suitable configuration within the applicable range, other than the preferred configuration example in which the heater wire 41 is embedded in the planar insulating film 42. For example, it is also preferred that the heater wire 41 is fixed to the back side or inner side of the insulating film 42 located toward the center of the vehicle, and further, it is also preferred that the heater wire 41 is fixed to the back side or inner side of the insulating film 42 located toward the center of the vehicle, and a protective film is laminated and fixed to the insulating film 42 so as to cover the heater wire 41 from the back side.

[0022] Both ends of the heater wire 41 are electrically connected to and mechanically fixed to the connector 6 at the bottom of the radome 1 for the vehicle-mounted radar device in the illustrated example, and power is supplied to the heater wire 41 via the connector 6 and an electric cable (not shown) connected to it, causing the heater wire 41 to generate heat.

[0023] The heater wire 41 is formed as a continuous wire that meanders and folds back in the direction in which the back surface 31 of the base material 3 expands or along the back surface 31, and straight portions 411 of the heater wire 41 are arranged in parallel at intervals in the electromagnetic wave irradiation region R of the base material 3 and outside thereof along the surface direction of the base material 3 or along the back surface 31, and the directions of currents flowing in the straight portions 411 of adjacent heater wires 41 are set to be approximately anti-parallel or anti-parallel to each other. By setting the directions of currents flowing in the straight portions 411 of adjacent heater wires 41 to be approximately anti-parallel or anti-parallel to each other, the electromagnetic waves radiated from the straight portions 411 of adjacent heater wires 41 have opposite phases, and the electromagnetic radiation from the straight portions 411 of the heater wires 41 is canceled out, making it possible to obtain better electromagnetic wave transmission performance. In this embodiment, at least four straight portions 411 of the heater wire 41 are arranged side by side at an approximate pitch P in the electromagnetic wave irradiation region R of the base material 3, and in the illustrated example, four straight portions 411 of the heater wire 41 are arranged side by side at an approximate pitch P in the electromagnetic wave irradiation region R of the base material 3.

[0024] Furthermore, in this embodiment, the straight line portions 411m of the heater wire 41 within the electromagnetic wave irradiation region R of the base material 3 and the straight line portions 411n of the heater wire 41 outside the electromagnetic wave irradiation region R adjacent to each other are arranged at a pitch P that is similar to the pitch P between the straight line portions 411 of the heater wire 41 within the electromagnetic wave irradiation region R, and the straight line portions 411n of the heater wire 41 outside the electromagnetic wave irradiation region R extend so as to be approximately antiparallel to each other and for a length that is equal to or longer than the length within the electromagnetic wave irradiation region R of the straight line portion 411m of the heater wire 41 adjacent to each other. In the illustrated example, the pitch P between the straight portions 411m and 411n of the heater wire 41 is set to be similar to the pitch P between the straight portions 411 of the heater wire 41 within the electromagnetic wave irradiation region R, the straight portion 411n of the heater wire 41 extends substantially anti-parallel to the straight portion 411m with substantially the same length, and the straight portion 411n extends outside the electromagnetic wave irradiation region R so as to be substantially anti-parallel to the straight portion 411m with a length longer than the length of the straight portion 411m within the electromagnetic wave irradiation region R. Note that in this embodiment, the approximation of the approximate pitch P between the straight portions 411 of the heater wire 41, including the straight portions 411m and 411n, means that, when the minimum pitch Pmin, the maximum pitch Pmax, and the intermediate pitch Pmid are defined as the minimum pitch Pmin and the maximum pitch Pmax, the ratio of the minimum pitch Pmin to the intermediate pitch Pmid is 0.80 or more and the ratio of the maximum pitch Pmax to the intermediate pitch Pmid is 1.2 or less.

[0025] Furthermore, in the radome 1 for an automotive radar device of this embodiment, the heater wire 41 is arranged so that the surface occupancy rate of the straight portion 411 of the heater wire 41 is set to be 1% or more and 24% or less in the electromagnetic wave irradiation region R of the substrate 3.

[0026] In the present embodiment, in the case of an on-vehicle radar structure in which the straight portions 411 of the heater wire 41 are arranged in parallel so as to extend substantially perpendicular or perpendicular to the polarization plane of the linearly polarized electromagnetic waves irradiated by the on-vehicle radar device 10 described later, it is preferable to set the surface occupancy rate of the straight portions 411 of the heater wire 41 to 1% or more and 24% or less in the electromagnetic wave irradiation region R of the substrate 3. As an example of this configuration, when the pitch P between the straight portions 411 of the heater wire 41 is 7.0 mm, the line width W of the straight portions 411 is 0.07 mm to 1.68 mm. More preferably, the surface occupancy rate of the straight line portions 411 of the heater wire 41 in the electromagnetic wave irradiation region R of the base material 3 is set to be 1% or more and 20% or less, or the surface occupancy rate of the straight line portions 411 of the heater wire 41 in the electromagnetic wave irradiation region R of the base material 3 is set to be 3% or more and 24% or less, or the surface occupancy rate of the straight line portions 411 of the heater wire 41 in the electromagnetic wave irradiation region R of the base material 3 is set to be 3% or more and 20% or less. In an example of a configuration in which the surface occupancy rate of the straight line portions 411 of the heater wire 41 in the electromagnetic wave irradiation region R of the base material 3 is set to be 3% or more and 20% or less, when the pitch P between the straight line portions 411 of the heater wire 41 is 7.0 mm, the line width W of the straight line portions 411 is 0.21 to 1.40 mm.

[0027] Furthermore, in the present embodiment, in an on-vehicle radar structure in which the straight portions 411 of the heater wire 41 are arranged side by side so as to extend substantially parallel to or parallel to the plane of polarization of linearly polarized electromagnetic waves irradiated by the on-vehicle radar device 10 described later, it is preferable to set the surface occupancy rate of the straight portions 411 of the heater wire 41 to 1% or more and 16% or less in the electromagnetic wave irradiation region R of the substrate 3. As an example of this configuration, when the pitch P between the straight portions 411 of the heater wire 41 is 7.0 mm, the line width W of the straight portions 411 is 0.07 to 1.12 mm. More preferably, the surface occupancy rate of the straight line portions 411 of the heater wire 41 in the electromagnetic wave irradiation region R of the base material 3 is set to be 1% or more and 13% or less, or the surface occupancy rate of the straight line portions 411 of the heater wire 41 in the electromagnetic wave irradiation region R of the base material 3 is set to be 3% or more and 16% or less, or the surface occupancy rate of the straight line portions 411 of the heater wire 41 in the electromagnetic wave irradiation region R of the base material 3 is set to be 3% or more and 13% or less. In an example of a configuration in which the surface occupancy rate of the straight line portions 411 of the heater wire 41 in the electromagnetic wave irradiation region R of the base material 3 is set to be 3% or more and 13% or less, when the pitch P between the straight line portions 411 of the heater wire 41 is 7.0 mm, the line width W of the straight line portions 411 is 0.21 to 0.91 mm.

[0028] Furthermore, from the viewpoint of improving electromagnetic wave transmission performance, it is preferable that the insulating film 42, or the insulating film 42 and the protective film when a protective film is laminated and fixed to the insulating film 42, have a refractive index n defined based on the complex dielectric constant that matches or is approximately the same as or close to that of the substrate 3. It is preferable that the numerical ranges of the refractive index n between the substrate 3 and the insulating film 42, the refractive index n between the substrate 3 and the protective film, and the refractive index n between the insulating film 42 and the protective film differ by 0 to 10%.

[0029] Here, the refractive index n is a quantity defined by the real part εr' of the relative dielectric constant and the imaginary part εr" as shown in Equation 1. Furthermore, from the viewpoint of transparency, it is preferable to use materials for the substrate 3, insulating film 42, and protective film, each of which has a dielectric loss tangent tanδ of 0.1 or less, which is defined by Equation 2 from the ratio of the imaginary part to the real part at the applicable frequency. It is also preferable to set the magnitude of the real part of the relative dielectric constant to 3 or less. By setting the magnitudes of the dielectric loss tangent and the real part of the dielectric constant to be equal to or less than these numerical values, it is possible to ensure the reflectance and internal loss reduction required for the radome.

[0030]

number

[0031]

number

[0032] The heater sheet 4 in this embodiment is fixed to the inner surface or rear surface of the substrate 3 via an adhesive layer 5. The adhesive layer 5 is made of an appropriate applicable electromagnetic wave-transmitting insulating material, and can be formed, for example, from an adhesive such as methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, or ethyl methacrylate, or from a double-sided tape made of an acrylic or silicone adhesive with a core material such as PET, polypropylene, or acrylic foam, or from a double-sided tape with only an adhesive without a core material. Note that instead of a configuration in which the heater sheet 4 is fixed to the substrate 3 via the adhesive layer 5, it is also preferable to fix the heater sheet 4 to the substrate 3 by welding the heater sheet 4 and the insulating film 42.

[0033] From the viewpoint of improving electromagnetic wave transmission performance, it is preferable to use a material for the adhesive layer 5 whose refractive index n, defined based on the complex dielectric constant, matches or is approximately the same or close to that of the substrate 3 and the insulating film 42, or to that of the substrate 3, the insulating film 42, and the protective film. It is preferable that the difference between the refractive indexes n of the adhesive layer 5 and the substrate 3, the adhesive layer 5 and the insulating film 42, and the adhesive layer 5 and the protective film be within a range of 0 to 10%. These refractive indices n are also quantities defined by Equation 1 using the real part εr' and the imaginary part εr" of the relative dielectric constant. From the viewpoint of transmission performance, it is preferable to use a material for the adhesive layer 5 whose dielectric loss tangent tanδ, defined by Equation 2 using the ratio of the imaginary part to the real part at the applicable frequency, is 0.1 or less. It is also preferable that the real part of the relative dielectric constant is 3 or less.

[0034] 4, the radome 1 for the automotive radar device is disposed in front of the automotive radar device 10 disposed toward the center of the vehicle and attached to the vehicle, thereby forming an automotive radar structure. The automotive radar device 10 irradiates linearly polarized electromagnetic waves onto the radome 1 for the automotive radar device. The wavelength or frequency of the electromagnetic waves irradiated by the automotive radar device 10 may be appropriate as needed, and may be, for example, millimeter waves in the 76 / 77 GHz band from 76.0 to 77.0 GHz or the 76 / 79 GHz band from 76.0 to 79.0 GHz.

[0035] Although the radome 1 for an automotive radar device in the illustrated example is a bumper cover, the radome for an automotive radar device of the present invention can be configured with an appropriate vehicle-mounted component such as an emblem-shaped radome. Furthermore, an appropriate laminated material can be additionally disposed in the normal direction of the substrate 3 as needed on the base 2 of the radome 1 for an automotive radar device. For example, in a bumper cover or an emblem-shaped radome, the heater sheet 4 can be laminated on the inner surface or back surface of the substrate 3 on the vehicle center side, and an electromagnetic wave-transmitting rear substrate 71 can be fixed thereto by adhesion or welding. Alternatively, the electromagnetic wave-transmitting decorative layer 72 and a transparent substrate 73 can be laminated on the outer surface or front surface of the substrate 3 on the vehicle's outer surface side, or the transparent substrate 73 can be laminated on the substrate 3 and fixed thereto by adhesion or welding (see FIG. 5 ).

[0036] In this case, it is preferable that the difference between the refractive index of the rear substrate 71 and the refractive index of the insulating film 42 of the substrate 3, the heater sheet 4, or the insulating film 42 and the protective film, or the adhesive layer 5 (if an adhesive layer 5 is interposed) is within a range of 0 to 10%. Also, it is preferable that the difference between the refractive index of the transparent substrate 73 and the refractive index of the insulating film 42 of the substrate 3, the heater sheet 4, or the insulating film 42 and the protective film, or the adhesive layer 5 (if an adhesive layer 5 is interposed) is within a range of 0 to 10%. Furthermore, it is preferable that the material for the rear substrate 71 and the transparent substrate 73 has a dielectric loss tangent (tan δ) defined by Equation 2 of 0.1 or less, and further, it is preferable that the real part of the relative dielectric constant is 3 or less. The configuration of the electromagnetic wave-transmitting decorative layer is appropriate within the scope of the present invention. For example, a decorative layer composed of a discontinuous metal film and colored portions, which are divided into islands by cracks and have integrated visibility, or a decorative layer composed only of a discontinuous metal film, is possible.

[0037] According to the radome 1 for an in-vehicle radar device of this embodiment, by setting the surface occupancy rate of the straight portion 411 of the heater wire 41 in the electromagnetic wave irradiation region R of the base material 3 to 1% or more, it is possible to maintain the temperature of the outer surface of the base material 3 at above 0°C even when the ambient temperature is -5°C and the vehicle is traveling at a speed of 100 km / h. Therefore, it is possible to suppress the attenuation of the electromagnetic waves irradiated by the in-vehicle radar device 10 within a required allowable range, and to exhibit a practical snow-melting function as the radome 1 for an in-vehicle radar device.

[0038] Furthermore, when the straight portions 411 of the heater wire 41 are arranged in parallel so as to extend approximately perpendicular to the polarization plane of the linearly polarized electromagnetic waves irradiated by the vehicle-mounted radar device 10, and the surface occupancy rate of the straight portions 411 of the heater wire 41 in the electromagnetic wave irradiation area R of the substrate 3 is set to 1% or more and 24% or less, the radome 1 for the vehicle-mounted radar device can exhibit a practical snow-melting function, and the transmittance of the substrate 2 to the electromagnetic waves irradiated by the vehicle-mounted radar device 10 can be ensured to be -1.5dB or more, and the attenuation of the electromagnetic waves can be suppressed within an allowable range that is high enough for practical use.

[0039] Furthermore, when the straight portions 411 of the heater wire 41 are arranged in parallel so as to extend substantially perpendicular to the polarization plane of the linearly polarized electromagnetic waves irradiated by the automotive radar device 10, and the surface occupancy rate of the straight portions 411 of the heater wire 41 in the electromagnetic wave irradiation region R of the substrate 3 is set to 3% to 20%, the temperature of the outer surface of the substrate 3 can be kept above 0°C even when the ambient temperature is -15°C and the vehicle is traveling at a speed of 100 km / h, thereby ensuring reliable snow melting on the radome 1 for an automotive radar device even in more severe cold environments. Furthermore, the transmittance of the substrate 2 to the electromagnetic waves irradiated by the automotive radar device 10 can be guaranteed to be -1.0 dB or higher, and the attenuation of the electromagnetic waves can be suppressed within a very high allowable range that is sufficient for practical use.

[0040] Furthermore, when the straight portions 411 of the heater wire 41 are arranged in parallel so as to extend approximately parallel to the polarization plane of the linearly polarized electromagnetic waves irradiated by the automotive radar device 10, and the surface occupancy rate of the straight portions 411 of the heater wire 41 in the electromagnetic wave irradiation area R of the substrate 3 is set to 1% or more and 16% or less, the radome 1 for the automotive radar device can exhibit a practical snow-melting function, and the transmittance of the substrate 2 to the electromagnetic waves irradiated by the automotive radar device 10 can be ensured to be -1.5dB or more, and the attenuation of the electromagnetic waves can be suppressed within an allowable range that is high enough for practical use.

[0041] Furthermore, when the straight portions 411 of the heater wire 41 are arranged so as to extend substantially parallel to the polarization plane of the linearly polarized electromagnetic waves irradiated by the automotive radar device 10, and the surface occupancy rate of the straight portions 411 of the heater wire 41 in the electromagnetic wave irradiation region R of the substrate 3 is set to 3% to 13%, the temperature of the outer surface of the substrate 3 can be kept above 0°C even when the ambient temperature is -15°C and the vehicle is traveling at a speed of 100 km / h, thereby ensuring reliable snow melting on the radome 1 for the automotive radar device even in more severe cold environments. Furthermore, the transmittance of the substrate 2 to the electromagnetic waves irradiated by the automotive radar device 10 can be guaranteed to be -1.0 dB or higher, and the attenuation of the electromagnetic waves can be suppressed within a very high allowable range that is sufficient for practical use.

[0042] Furthermore, according to the radome 1 for an automotive radar device, the directions of currents flowing in the straight portions 411 of adjacent heater wires 41 are made antiparallel to each other, so that the electromagnetic waves radiated from adjacent heater wires are in opposite phases, thereby canceling out the electromagnetic radiation from the heater wires 41 and achieving better electromagnetic wave transmission performance. Furthermore, by arranging at least four straight portions 411 of the heater wires 41 in parallel at similar pitches in the electromagnetic wave irradiation region R of the base material 3, the temperature distribution in the entire electromagnetic wave irradiation region R of the base material 3 can be made more uniform, preventing the occurrence of localized regions with low temperatures when the heater wires are heated, and more reliably melting snow throughout the entire electromagnetic wave irradiation region R of the base material 3.

[0043] Furthermore, by arranging the straight line portions 411m of the heater wire 41 inside the electromagnetic wave irradiation region R and the straight line portions 411n of the heater wire 41 outside the electromagnetic wave irradiation region R adjacent to each other at a pitch similar to the pitch between the straight line portions 411 of the heater wire 41 inside the electromagnetic wave irradiation region R, and extending the straight line portions 411n of the heater wire 41 outside the electromagnetic wave irradiation region R by a length equal to or longer than the length within the electromagnetic wave irradiation region R of the straight line portions 411m of the heater wire 41 in the adjacent electromagnetic wave irradiation region R, it is possible to cancel out the electromagnetic radiation of the straight line portions 411m of the heater wire 41 inside the electromagnetic wave irradiation region R located near the periphery of the electromagnetic wave irradiation region R with high certainty, regardless of whether the number of straight line portions 411 juxtaposed within the electromagnetic wave irradiation region R is an even number or an odd number, and thereby obtaining even better electromagnetic wave transmission performance.

[0044] [Experimental example regarding the surface occupancy rate of heater wire, electromagnetic wave transmittance, and snow melting performance] 6 and 7 was prepared as a sample corresponding to the base of the radome for an automotive radar device of the present invention and the base 2 of the radome 1 for an automotive radar device of the above embodiment, and experiments were conducted to verify the electromagnetic wave transmittance and the snow melting property using the sample 20. The sample 20 is composed of a base material 21 corresponding to the base material 3, a heater sheet 22 corresponding to the heater sheet 4, and a double-sided tape 23 corresponding to the adhesive layer 5, and the double-sided tape 23 and the heater sheet 22 are laminated in this order on the back side or inner side of the base material 21 that is irradiated with electromagnetic waves, and the heater sheet 22 is fixed to the base material 21 via the double-sided tape 23.

[0045] The substrate 21 was a flat plate with a thickness of 2.2 mm, the double-sided tape 23 was a plane with a thickness of 0.1 mm, and the heater sheet 22 was a plane with a thickness of 0.1 mm, and the total thickness of the approximately flat plate-shaped sample formed by stacking these components was 2.4 mm. The substrate 21 was an ABS resin plate, and more specifically, it was formed from a heat-resistant ABS resin (MTH-2) manufactured by Nippon A&L Co., Ltd. At room temperature (approximately 25°C), this ABS (MTH-2) had a complex permittivity ε' of 2.656 and a dielectric loss tangent tanδ of 0.0065 for electromagnetic waves (millimeter waves) in the 76 / 77 GHz band.

[0046] The heater sheet 22 is configured such that the heater wire 221 is embedded in the insulating film 222 so that the heater wire 221 and its terminal 2212 are exposed on the back side of the insulating film 222. The insulating film 222 is a polyimide film, and the heater wire 221 is a copper wire (resistivity 1.69×10 -8 The dielectric constant ε' of the polyimide film that is the insulating film 222 for electromagnetic waves (millimeter waves) in the 76 / 77 GHz band at room temperature (approximately 25°C) is 3.247, and the dielectric tangent tanδ is 0.0054. The heater wire 221 is formed so as to meander and fold back along the insulating film 222, extending continuously, with straight portions 2211 arranged in parallel at intervals along the insulating film 222. The pitch P between the straight portions 2211 of the heater wire 221 of sample 20 is 7.0 mm, and the pitch P between all of the straight portions 2211 is the same.

[0047] The double-sided tape 23 is made of an acrylic adhesive without a core material, and has a complex dielectric constant ε' of 2.513 and a dielectric loss tangent tanδ of 0.0139 for electromagnetic waves (millimeter waves) in the 76 / 77 GHz band at room temperature (approximately 25° C.).

[0048] Measurements of an experiment to verify the electromagnetic wave transmittance using sample 20 were carried out using a Quality Automobile Radome Tester (QAR) manufactured by ROHDE & SCHWARZ as the measurement device. In the schematic diagram of this measurement device shown in Figure 6, 101 is the electromagnetic wave transmission unit, 102 is the reception unit, and 103 is the evaluation device. The electromagnetic waves transmitted from electromagnetic wave transmission unit 101 used in the measurement are millimeter waves in the 76 / 77 GHz band. EW is the propagation direction of the millimeter waves.

[0049] Then, electromagnetic waves were irradiated from the electromagnetic wave emitting unit 101 to the sample 20 so that R shown in Figure 7 was the electromagnetic wave irradiation area, and the electromagnetic wave transmittance was measured when the electromagnetic waves were irradiated so that the polarization plane LP of the linearly polarized millimeter wave in the 76 / 77 GHz band was perpendicular to the straight part 2211 of the heater wire 221 of the sample 20 (see Figure 7(a)), and also when the electromagnetic waves were irradiated so that the polarization plane LP of the linearly polarized millimeter wave in the 76 / 77 GHz band was parallel to the straight part 2211 of the heater wire 221 of the sample 20 (see Figure 7(b)).

[0050] In measuring the electromagnetic wave transmittance, for both the case where the polarization plane LP is perpendicular to the straight line portion 2211 and the case where the polarization plane LP is parallel to the straight line portion 2211, the line width W of the straight line portion 2211 was changed while maintaining the pitch of 7.0 mm, to change the occupancy rate of the heater wire 221 or its straight line portion 2211 in the entire area of ​​the electromagnetic wave irradiation region R, and measurements were taken without applying current to the heater wire 221. The measurement results are shown in Fig. 8.

[0051] 8, it can be seen that when the allowable value of electromagnetic wave transmission attenuation of sample 20 corresponding to the base of a radome for an automotive radar device is set to be −1.5 dB or more, in a structure in which the polarization plane LP of linearly polarized electromagnetic waves is irradiated perpendicularly to the straight portion 2211 of the heater wire 221, this can be achieved by setting the surface occupancy rate of the straight portion 2211 of the heater wire 221 in the electromagnetic wave irradiation region R of the substrate 21 to 24% or less. Also, in a structure in which the polarization plane LP of linearly polarized electromagnetic waves is irradiated parallel to the straight portion 2211 of the heater wire 221, it can be seen that a similar allowable value can be achieved by setting the surface occupancy rate of the straight portion 2211 of the heater wire 221 in the electromagnetic wave irradiation region R of the substrate 21 to be 16% or less.

[0052] Furthermore, it is found that when the allowable value of electromagnetic wave transmission attenuation of sample 20 corresponding to the base of a radome for an automotive radar device is set to be -1.0 dB or more, in a structure in which the polarization plane LP of linearly polarized electromagnetic waves is irradiated perpendicularly to the straight portion 2211 of the heater wire 221, this can be achieved by setting the surface occupancy rate of the straight portion 2211 of the heater wire 221 in the electromagnetic wave irradiation region R of the substrate 21 to 20% or less. Also, in a structure in which the polarization plane LP of linearly polarized electromagnetic waves is irradiated parallel to the straight portion 2211 of the heater wire 221, it is found that a similar allowable value can be achieved by setting the surface occupancy rate of the straight portion 2211 of the heater wire 221 in the electromagnetic wave irradiation region R of the substrate 21 to be 13% or less.

[0053] Furthermore, in a structure in which the polarization plane LP of the linearly polarized electromagnetic wave is irradiated perpendicularly to the straight portion 2211 of the heater wire 221, it is found that an extremely high electromagnetic wave transmittance can be achieved, with an electromagnetic wave transmittance of -0.4 dB or more when the surface occupancy rate of the straight portion 2211 of the heater wire 221 in the electromagnetic wave irradiation region R of the substrate 21 is 10% or less, and an electromagnetic wave transmittance of -0.35 dB or more when the surface occupancy rate of the straight portion 2211 of the heater wire 221 in the electromagnetic wave irradiation region R of the substrate 21 is 7.5% or less.

[0054] Furthermore, in an experiment to verify the snow melting performance using sample 20, sample 20 was placed in front of the vehicle with the vehicle traveling in the forward direction, and the heater wire 221 of sample 20 was energized with an input voltage of 10 V, and the vehicle speed was set to 100 km / h. While maintaining a pitch of 7.0 mm, the line width W of the straight portion 2211 was changed to change the occupancy rate of the heater wire 221 or its straight portion 2211 in the entire area of ​​the electromagnetic wave irradiation region R, and experiments were conducted at ambient temperatures of -5°C and -15°C. The measurement results are shown in FIG. 9.

[0055] 9 shows that when the ambient temperature is -5°C and the vehicle is traveling at 100 km / h, the temperature of the outer surface of the substrate 21 (the front surface in the vehicle traveling direction) can be made to exceed 0°C by setting the surface occupancy rate of the straight portions 2211 of the heater wire 221 in the electromagnetic wave irradiation region R of the substrate 21 to 1% or more. Also, when the ambient temperature is -15°C and the vehicle is traveling at 100 km / h, the temperature of the outer surface of the substrate 21 (the front surface in the vehicle traveling direction) can be made to exceed 0°C by setting the surface occupancy rate of the straight portions 2211 of the heater wire 221 in the electromagnetic wave irradiation region R of the substrate 21 to 3% or more.

[0056] 10 shows the relationship between the surface occupancy of the heater wire 221, the electromagnetic wave transmittance, and the outer surface temperature of the sample 20 when the sample 20 is irradiated with the polarization plane LP of linearly polarized electromagnetic waves perpendicular to the straight portion 2211 of the heater wire 221. In a structure in which the polarization plane LP of linearly polarized electromagnetic waves is irradiated perpendicular to the straight portion 2211 of the heater wire 221, from the viewpoint of achieving a required electromagnetic wave transmittance while exhibiting a practical snow-melting function, the lower limit of the surface occupancy of the heater wire 221 or its straight portion 2211 is preferably 1% or more, more preferably 3% or more, and the upper limit is preferably 24% or less, more preferably 20% or less. Furthermore, to obtain extremely excellent electromagnetic wave transmittance, the upper limit of the surface occupancy of the heater wire 221 or its straight portion 2211 is more preferably 10% or less, and even more preferably 7.5% or less.

[0057] 11 shows the relationship between the surface occupancy rate of the heater wire 221, the electromagnetic wave transmittance, and the outer surface temperature of the sample 20 when the sample 20 is irradiated with the polarization plane LP of linearly polarized electromagnetic waves parallel to the straight portion 2211 of the heater wire 221. In a structure in which the polarization plane LP of linearly polarized electromagnetic waves is irradiated parallel to the straight portion 2211 of the heater wire 221, from the viewpoint of achieving a required electromagnetic wave transmittance while exhibiting a practical snow-melting function, the lower limit of the surface occupancy rate of the heater wire 221 or its straight portion 2211 is preferably 1% or more, more preferably 3% or more, and the upper limit is preferably 16% or less, more preferably 13% or less.

[0058] [Scope of the invention disclosed herein] The inventions disclosed in this specification include, in addition to the individual inventions and embodiments listed as inventions, those specified by modifying partial contents of these with other contents disclosed in this specification, those specified by adding other contents disclosed in this specification to these contents, or those specified by deleting partial contents of these to the extent that partial effects can be obtained and creating a generic concept. The inventions disclosed in this specification also include the following modifications and additions.

[0059] For example, the radome for an on-vehicle radar device of the present invention appropriately includes one having an electromagnetic wave transparent substrate and a base body having a heater wire laminated on the inner surface of the substrate and wired in the surface direction of the substrate, and also includes a radome having a structure in which the heater wire is laminated on the inner surface of the substrate and directly fixed thereto without using a heater sheet 4. [Industrial Applicability]

[0060] The present invention can be used as a radome for an on-vehicle radar device and an on-vehicle radar structure. [Explanation of symbols]

[0061] REFERENCE SIGNS LIST 1...Radome for automotive radar device 2...Base 3...Substrate 31...Rear surface 4...Heater sheet 41...Heater wire 411, 411m, 411n...Straight section 42...Insulating film 5...Adhesive layer 6...Connector 71...Rear substrate 72...Decorative layer 73...Transparent member 10...Automotive radar device 20...Sample 21...Substrate 22...Heater sheet 221...Heater wire 2211...Straight section 2212...Terminal 222...Insulating film 23...Double-sided tape 101...Electromagnetic wave transmitter 102...Receiver 103...Evaluation device R...Electromagnetic wave irradiation area P...Pitch between straight sections of heater wire W...Width of straight section of heater wire EW...Propagation direction of millimeter wave LP...Polarization plane (polarization direction) of linearly polarized wave

Claims

1. a base body including an electromagnetic wave transparent substrate and a heater wire laminated on an inner surface of the substrate on the vehicle center side, which is in front of an on-vehicle radar device disposed on the vehicle center side, and wired in a surface direction of the substrate; the linear portions of the heater wire are arranged in parallel at intervals in the surface direction of the substrate in the electromagnetic wave irradiation region of the substrate, the linear portions of the heater wires are arranged in parallel so as to extend substantially perpendicular to the plane of polarization of the linearly polarized electromagnetic waves irradiated by the on-vehicle radar device, the surface occupancy rate of the linear portion of the heater wire in the electromagnetic wave irradiation region of the substrate is set to 1% or more and 24% or less; The heater wire and an electromagnetic wave-transmitting insulating film constitute a heater sheet, The heater sheet is laminated and fixed to the inner surface of the substrate, thereby wiring the heater wire, a refractive index defined based on the complex dielectric constant of the substrate and a refractive index defined based on the complex dielectric constant of the insulating film match or are close to each other, The radome for an on-vehicle radar device is characterized in that the insulating film is fixed to the base material by welding the surface of the insulating film facing the base material to the base material.

2. 2. The radome for an on-vehicle radar device according to claim 1, wherein the surface occupancy rate of the linear portion of the heater wire in the electromagnetic wave irradiation region of the base material is set to 3% to 20%.

3. a base body including an electromagnetic wave transparent substrate and a heater wire laminated on an inner surface of the substrate on the vehicle center side, which is in front of an on-vehicle radar device disposed on the vehicle center side, and wired in a surface direction of the substrate; the linear portions of the heater wire are arranged in parallel at intervals in the surface direction of the substrate in the electromagnetic wave irradiation region of the substrate, the linear portions of the heater wires are arranged in parallel so as to extend substantially parallel to the plane of polarization of the linearly polarized electromagnetic waves irradiated by the on-vehicle radar device, the surface occupancy rate of the linear portion of the heater wire in the electromagnetic wave irradiation region of the substrate is set to 1% or more and 16% or less; The heater wire and an electromagnetic wave-transmitting insulating film constitute a heater sheet, The heater sheet is laminated and fixed to the inner surface of the substrate, thereby wiring the heater wire, a refractive index defined based on the complex dielectric constant of the substrate and a refractive index defined based on the complex dielectric constant of the insulating film match or are close to each other, The radome for an on-vehicle radar device is characterized in that the insulating film is fixed to the base material by welding the surface of the insulating film facing the base material to the base material.

4. 4. The radome for an on-vehicle radar device according to claim 3, wherein the surface occupancy rate of the linear portion of the heater wire in the electromagnetic wave irradiation region of the base material is set to 3% or more and 13% or less.

5. 5. The radome for an on-vehicle radar device according to claim 1, wherein the insulating film is planar and has no through-holes that penetrate in the electromagnetic wave irradiation direction of the on-vehicle radar device.

6. 6. The radome for an on-vehicle radar device according to claim 5, wherein an electromagnetic wave transparent rear substrate disposed on the inner surface side of the substrate is fixed to the insulating film of the heater sheet.

7. A radome for an on-vehicle radar device according to any one of claims 1 to 6; An on-vehicle radar structure comprising an on-vehicle radar device that irradiates a linearly polarized electromagnetic wave onto the radome for the on-vehicle radar device.

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