Electromagnetic wave scattering body and member for attenuating electromagnetic waves having electromagnetic wave scattering body

Abstract

By the new configuration, a member capable of transmitting and attenuating an incident electromagnetic wave without mixing an electromagnetic wave absorbing material, a scatterer, and the like is provided. An electromagnetic wave scatterer is characterized by being configured in such a manner that at least a part of an incident electromagnetic wave is transmitted and the transmitted electromagnetic wave is emitted in a scattered state, and the electromagnetic wave scatterer is formed of a resin composition in which a resin is a main component.

Description

Technical Field

[0001] The present invention relates to an electromagnetic wave attenuator for attenuating incident electromagnetic waves, and to a component having an electromagnetic wave attenuator for attenuating electromagnetic waves. Background Technology

[0002] In recent years, research has been conducted in fields such as automobiles, home appliances, and life sciences on information detection methods that use radio waves (especially millimeter waves) as the information communication medium. For example, in the field of automotive technology, there is a collision prevention system that uses radar with radio waves in the 24-81 GHz frequency range to detect obstacles and automatically brake, or to determine the speed and distance of surrounding vehicles and control the speed and distance of the vehicle itself. For collision prevention systems to function properly, it is important to minimize the reception of unwanted radio waves (noise) to prevent false alarms.

[0003] Figure 1 An example of the radar setup used in this collision prevention system is shown, in which a radar 36 and a cover member 31 relative to the radar 36 are disposed within the bumper 38 of the vehicle. The radar 36 is mounted such that it is surrounded by the side peripheral walls 34 of the cover member 31. Radio waves β1 emitted from the radar 36 typically penetrate the bumper 38, and there are radio waves (radio waves β2) reflected (including multiple reflections) by the bumper 38 that reach the radar 36 or its vicinity. Therefore, radar malfunctions can sometimes occur.

[0004] To prevent such erroneous operation, a technique is proposed in which an electromagnetic wave absorber is provided on the surface of the cover member 31 to absorb and eliminate unwanted electromagnetic waves, suppress the amount of electromagnetic wave β2 reaching the radar 36, and prevent erroneous operation of the radar 36. As an electromagnetic wave absorber, for example, as shown in Patent Document 1 below, an electromagnetic wave absorber made of carbon particles that absorb electromagnetic waves is proposed. Furthermore, as shown in Patent Document 2 below, an electromagnetic wave absorber made of a scattering agent that scatters electromagnetic waves is proposed. It should be noted that although it is also described that multiple recesses are formed on the electromagnetic wave incident surface, this is based on the premise of containing a scattering agent.

[0005] In addition, the following technology (Patent Document 3 below) is proposed, in order to prevent the reflected waves generated by the bumper 38 from forming strong electromagnetic waves in a specific direction, by providing components with surfaces shaped to cause diffuse reflection of incident electromagnetic waves at the reflection point of the bumper 38 and at necessary positions of the shielding plate, thereby dispersing the energy of the reflected waves.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2001-230587

[0009] Patent Document 2: Japanese Patent Application Publication No. 2004-153135

[0010] Patent Document 3: Japanese Patent No. 5696781 Summary of the Invention

[0011] The problem the invention aims to solve

[0012] However, the radio wave absorber shown in Patent Document 1 has increased cost due to the mixing of carbon particles, and the weight of the radio wave absorber is also increased because the mixed carbon particles are heavy.

[0013] Furthermore, the electromagnetic wave absorber shown in Patent Document 2 has a higher cost because it incorporates a scatterer (a second dielectric material). Additionally, research is needed to disperse and arrange the scatterer within the electromagnetic wave absorber.

[0014] The inventors have discovered that even with a component formed solely from a resin composition that allows incident electromagnetic waves to pass through, by studying its shape, it is possible to scatter electromagnetic waves emitted from the component, thereby attenuating the intensity of the emitted electromagnetic waves per unit area. Specifically, it has been discovered that incident electromagnetic waves can be attenuated without mixing dielectric loss materials such as carbon particles, magnetic loss materials such as iron oxide powder, or scatterers into the resin composition that allows incident electromagnetic waves to pass through. Furthermore, it is possible to attenuate incident electromagnetic waves using a configuration different from that used to cause diffuse reflection. Figure 2 This is a conceptual diagram illustrating the scattering of emitted radio waves based on this new configuration.

[0015] One of the objectives of this invention is to provide a component that can transmit and attenuate incident radio waves without mixing dielectric loss materials such as carbon particles, magnetic loss materials such as iron oxide powder, and scatterers through a new configuration.

[0016] Solution for solving the problem

[0017] One aspect of the present invention provides an electromagnetic wave scatterer configured such that at least a portion of an incident electromagnetic wave is transmitted and the transmitted electromagnetic wave is emitted in a scattered state, and is formed of a resin composition with resin as the main component.

[0018] The aforementioned resin composition may be a substance that allows at least 20% of an electromagnetic wave to be transmitted perpendicularly to a 3 mm thick plate formed from the aforementioned resin composition.

[0019] The aforementioned radio wave scatterer may be formed with a structural part having at least two surfaces, one constituting an incident surface and the other constituting an exit surface, wherein at least one of the aforementioned two surfaces generates radio wave scattering.

[0020] The aforementioned structural portion may consist of at least one protrusion and / or a hole.

[0021] When the wavelength of the incident radio wave is set to λ, the height of the aforementioned protrusion can be 0.26λ or more, the width of the aforementioned protrusion can be 0.12λ or more, and the spacing of the aforementioned protrusion can be 5.1λ or less, and / or the depth of the aforementioned hole can be 0.26λ or more, the width of the aforementioned hole can be 5.1λ or less, and the spacing of the aforementioned hole can be 0.12λ or more.

[0022] The aforementioned resin composition has a complex relative permittivity, and the imaginary part ε'' of the relative permittivity is less than 0.1 at any frequency from 10 to 300 GHz.

[0023] The real part ε' of the relative permittivity of the aforementioned resin composition is 2 or more and 4 or less at any frequency from 10 to 300 GHz.

[0024] One aspect of the present invention provides a component having the aforementioned radio wave scatterer for attenuating radio waves.

[0025] The aforementioned component for attenuating radio waves can be a molded body, and the aforementioned radio wave scatterer is formed in at least a portion thereof.

[0026] The aforementioned components used to attenuate radio waves can be radar shroud components.

[0027] One aspect of the present invention provides a radar assembly in which a radar is mounted on a radome member of the aforementioned radar.

[0028] One aspect of the present invention provides a bumper that includes the aforementioned components for attenuating radio waves.

[0029] One aspect of the present invention provides a vehicle having the aforementioned components, the aforementioned radar assembly, and / or the aforementioned bumper.

[0030] As described above, techniques for absorbing (attenuating) unwanted radio waves have existed for a long time. In the technology described in Patent Document 1, a radio wave loss material is actively introduced into the resin layer where the radio wave is incident, and this radio wave loss material is used to absorb (attenuate) unwanted radio waves. In the technology described in Patent Document 2, a scatterer (e.g., air) that scatters radio waves is contained within the resin layer where the radio wave is incident, and unwanted radio waves are absorbed (attenuated) by causing internal scattering within the resin layer. In the technology described in Patent Document 3, unwanted radio waves are suppressed by actively causing diffuse reflection of the incident radio wave, or by changing the angle of the reflected wave relative to the incident wave through reflection.

[0031] Therefore, it can be considered that the previously known technologies described in Patent Documents 1-3 are different from the technology of the present invention that scatters and attenuates electromagnetic waves penetrating the resin layer.

[0032] The effects of the invention

[0033] According to the present invention, a new configuration can be provided that can attenuate incident radio waves without mixing dielectric loss materials such as carbon particles, magnetic loss materials such as iron oxide powder, and scatterers.

[0034] Hereinafter, embodiments of the electromagnetic wave scatterer of the present invention will be described in detail with reference to the accompanying drawings. Attached Figure Description

[0035] Figure 1 This is a diagram showing an example of the radar setup used in a collision prevention system.

[0036] Figure 2 This is a conceptual diagram illustrating the scattering of emitted radio waves based on a new configuration.

[0037] Figure 3 This is a perspective view illustrating one embodiment of the electromagnetic wave scatterer of the present invention.

[0038] Figure 4 This is a top view illustrating one embodiment of the electromagnetic wave scatterer of the present invention.

[0039] Figure 5 yes Figure 4 VV cross-sectional diagram.

[0040] Figure 6 This is a diagram illustrating an overview of the methods for measuring scattering rate.

[0041] Figure 7 This is a conceptual diagram illustrating the relationship between scattering state and the method for measuring scattering rate.

[0042] Figure 8 This is a graph showing the relationship between the transmission attenuation based on measured values ​​and the height of the protrusion.

[0043] Figure 9 This is a graph showing the relationship between transmittance and the height of the protrusion based on scalar diffraction theory.

[0044] Figure 10 This is a cross-sectional view of an example of an electromagnetic wave scatterer formed by repeating units with protrusions of different widths.

[0045] Figure 11 This is a graph showing a comparison of the transmission attenuation at various angles of the sample from Example 14 and the sample from Example 3.

[0046] Figure 12 This is a cross-sectional view showing another embodiment of the electromagnetic wave scatterer of the present invention.

[0047] Figure 13This is a cross-sectional view showing another embodiment of the electromagnetic wave scatterer of the present invention.

[0048] Figure 14 This is a top view illustrating another embodiment of the electromagnetic wave scatterer of the present invention.

[0049] Figure 15 This is a top view illustrating another embodiment of the electromagnetic wave scatterer of the present invention.

[0050] Figure 16 This is a top view illustrating another embodiment of the electromagnetic wave scatterer of the present invention.

[0051] Figure 17 This is a top view illustrating another embodiment of the electromagnetic wave scatterer of the present invention.

[0052] Figure 18 This is a top view illustrating another embodiment of the electromagnetic wave scatterer of the present invention.

[0053] Figure 19 This is a top view illustrating another embodiment of the electromagnetic wave scatterer of the present invention.

[0054] Figure 20 This is a top view illustrating another embodiment of the electromagnetic wave scatterer of the present invention.

[0055] Figure 21 This is a top view illustrating another embodiment of the electromagnetic wave scatterer of the present invention.

[0056] Figure 22 This is a top view illustrating another embodiment of the electromagnetic wave scatterer of the present invention.

[0057] Figure 23 The diagram shows a top view and a cross-sectional view of an example of a structure in which the support portion of an electromagnetic wave scatterer has a hole.

[0058] Figure 24 This is a top view illustrating another embodiment of the electromagnetic wave scatterer of the present invention.

[0059] Figure 25 This is a top view illustrating another embodiment of the electromagnetic wave scatterer of the present invention.

[0060] Figure 26 This diagram illustrates the concept of convex volume ratio.

[0061] Figure 27 This is a perspective view of one embodiment of the component of the present invention for attenuating radio waves.

[0062] Figure 28A This is a top view of one embodiment of the component of the present invention for attenuating radio waves.

[0063] Figure 28B yes Figure 28A YY cross-sectional view.

[0064] Figure 28C yes Figure 28B ZZ cross-sectional view.

[0065] Figure 29A This is a top view of another embodiment of the component of the present invention for attenuating radio waves.

[0066] Figure 29B yes Figure 29A GG cross-sectional view.

[0067] Figure 30A This is a diagram illustrating a raised strip formed on the inner surface of the side wall of one embodiment of the component for attenuating radio waves according to the present invention.

[0068] Figure 30B This figure illustrates a modified example of a raised strip formed on the inner surface of the sidewall of one embodiment of the component for attenuating radio waves according to the present invention.

[0069] Figure 30C This figure illustrates a modified example of a raised strip formed on the inner surface of the sidewall of one embodiment of the component for attenuating radio waves according to the present invention.

[0070] Figure 31 This is a perspective view of one embodiment of the radar component of the present invention.

[0071] Figure 32 This is a schematic diagram illustrating one embodiment of the bumper of the present invention.

[0072] Figure 33 This is a diagram illustrating a summary of one embodiment of the vehicle of the present invention.

[0073] Figure 34 This diagram illustrates a general overview of the method for measuring reflection attenuation.

[0074] Figure 35A This is a graph illustrating an example of curve fitting in transmittance calculation.

[0075] Figure 35B This is a graph illustrating an example of curve fitting in transmittance calculation. Detailed Implementation

[0076] [Electronic wave scatterer]

[0077] The electromagnetic wave scatterer of the present invention is configured such that at least a portion of the incident electromagnetic wave is transmitted and the transmitted electromagnetic wave is emitted in a scattered state, and is formed of a resin composition with resin as the main component.

[0078] For the radio wave scatterer of the present invention, the aforementioned resin composition allows at least 50% transmission of radio waves incident perpendicularly to a 3 mm thick plate formed from the aforementioned resin composition. This transmittance is preferably 65% ​​or more, more preferably 85% or more. By setting this preferred transmittance, lightweight and low-cost production is possible without the need for dielectric loss materials. The transmittance of the radio wave scatterer is defined by the transmittance of radio waves incident perpendicularly to a 3 mm thick plate formed from the resin composition constituting the radio wave scatterer. One reason is that the ratio of total incident power to total emitted power varies with the shape of the radio wave scatterer. Another reason is that it is difficult to measure the total emitted power. As described above, in the present invention, even for a component formed solely from a resin composition that transmits incident radio waves, by studying its shape, it is possible to scatter radio waves emitted from the component. Therefore, it is reasonable to define the characteristics by the transmittance of a plate-shaped component containing a resin composition, which is representative of shapes that do not scatter emitted radio waves.

[0079] Figure 3 This is a perspective view illustrating one embodiment of the electromagnetic wave scatterer of the present invention. Figure 4 This is a top view illustrating one embodiment of the electromagnetic wave scatterer of the present invention. Figure 5 yes Figure 4 VV cross-sectional diagram.

[0080] The radio wave scatterer 1 comprises: a support portion 4 having a first main surface 2 and a second main surface 3; and a structural portion 5 formed on the first main surface 2, which scatters radio waves. The structural portion 5 is composed of a plurality of protrusions 6. In this embodiment, the protrusions 6 are raised strips, all extending in the same direction and formed parallel to each other.

[0081] The size of the radio wave scatterer 1 also depends on the size of the object being installed, etc., but its width Q and length P (refer to...) Figure 4 The material is typically formed in the shape of 1 to 50 cm, more preferably 1.5 to 40 cm, and even more preferably 3 to 30 cm. Furthermore, from the viewpoint of balancing strength and weight, Figure 5The thickness T1 of the support portion 4 shown is generally preferably designed to be in the range of 0.5 to 10 mm, more preferably in the range of 0.7 to 5 mm, and even more preferably in the range of 1 to 3 mm. In addition, from the viewpoint of achieving sufficient radio wave scattering effect, the thickness T2 of the radio wave scatterer 1, including the height H of the protrusion 6, is generally preferably designed to be in the range of 0.5 to 20 mm, more preferably in the range of 1 to 15 mm, and even more preferably in the range of 2 to 10 mm.

[0082] When the wavelength of the incident radio wave is set to λ, the height H of the protrusion 6 is preferably designed to be in the range of 0.26λ or more, more preferably in the range of 0.51λ or more and 1.5λ or less, and even more preferably in the range of 0.77λ or more and 1.3λ or less.

[0083] When the wavelength of the incident radio wave is set to λ, the width W of the portion of the protrusion 6 that rises from the first main surface 2 is preferably designed to be in the range of 0.26λ or more, more preferably in the range of 0.26λ or more and 3.1λ or less, and when the protrusion 6 is dot-shaped, it is even more preferably designed to be in the range of 0.51λ or more and 3.1λ or less.

[0084] Furthermore, when the wavelength of the incident radio wave is set to λ, the spacing S between adjacent protrusions 6 is preferably designed to be in the range of 5.1λ or less, more preferably in the range of 0.26λ or more and 3.1λ or less, and even more preferably in the range of 0.51λ or more and 2.6λ or less. Among these, the more preferred spacing S is 0.26λ or more and 2.8λ or less when the protrusion 6 is a raised strip, and 0.51λ or more and 2.6λ or less when the protrusion 6 is a dot. It should be noted that the spacing S is a value measured between opposing portions of the protrusion 6 that rise from the first main surface 2.

[0085] When the wavelength of the incident radio wave is set to λ, the height H, width W, and spacing S of the protrusion 6 are preferably designed to be in the range of 0.26λ or more, 0.12λ or more, and 5.1λ or less; more preferably, they are designed to be in the range of 0.51λ or more and 1.5λ or less, 0.26λ or more and 3.1λ or less, and 0.26λ or more and 3.1λ or less; even more preferably, they are designed to be in the range of 0.51λ or more and 1.5λ or less, 0.26λ or more and 3.1λ or less, and 0.51λ or more and 2.6λ or less. Among these, the more preferred ranges for height H, width W, and spacing S are 0.51λ or more and 1.5λ or less, 0.26λ or more and 3.1λ or less, and 0.26λ or more and 2.8λ or less when the protrusion 6 is a ridge, and 0.51λ or more and 1.5λ or less, 0.51λ or more and 3.1λ or less, and 0.51λ or more and 2.6λ or less when the protrusion 6 is a dot, respectively.

[0086] The performance of the electromagnetic wave scatterer with height H, width W, and spacing S of the protrusion 6 can be verified either by preparing and evaluating samples as described in the embodiments of this application, or by electromagnetic field analysis simulation.

[0087] As described above, the radio wave scatterer of the present invention is configured such that at least a portion of the incident radio wave is transmitted and the transmitted radio wave is emitted in a scattered state. "The transmitted radio wave is emitted in a scattered state" means that the scattering rate is a specified value based on a measurement obtained by means of ...

[0088] The method for measuring scattering rate is explained. Figure 6 This is a diagram illustrating an overview of the methods for measuring scattering rate. Figure 7 This is a conceptual diagram illustrating the relationship between the scattering state and the method for measuring the scattering rate. Referring to JIS R 1679, the transmission attenuation was measured at 60-90 GHz using a radio transceiver (EAS03, KEYCOM) in the order shown below. The transmission attenuation was expressed as the absolute value calculated by the following formula (1).

[0089] 10Log|P i / P0|...(1) (P i (P0: Receive power, P1: Transmit power)

[0090] like Figure 6 As shown in the summary, a sample holder 11, a millimeter-wave lens 12, a transmitter 9, and a receiver 10 are configured. Radio waves with a diameter of 150 mm are transmitted from the transmitter 9. Radio wave transmission and reception are performed with no object placed on the sample holder 11, and the state of 0 dB transmission attenuation (complete transmission of the radio wave) is used as the reference for measuring the transmission attenuation perpendicular to the surface direction of each sample. Next, the sample is placed on the sample holder 11, and then... Figure 7As shown, the receiver was set at angles of 0°, 15°, 30°, 45°, 60°, and 75° perpendicular to the surface direction of each sample and relative to the direction from transmitter 9 to receiver 10, respectively, for transmitting and receiving radio waves, and the transmission attenuation at 76.5 GHz was measured. It should be noted that when the structure of the radio wave scatterer is a convex strip, the long side of the convex strip formed on its first main surface is measured with the amplitude direction of the electric field of the incident wave perpendicular to it. Based on the measured values ​​of transmission attenuation at each angle of 0°, 15°, 30°, 45°, 60°, and 75°, P was calculated from the above formula (1). i / P0 (receive / transmit power ratio), and based on the calculated P... i / P0 (receive / transmit power ratio) is used to calculate scattering rate I and scattering rate II using the following equations (2.1) and (2.2).

[0091] (Scattering rate I) = (P at 15°, 30°, 45°, 60°, 75°) i / P0 (total of receive / transmit power ratio) / (P at 0°) i / P0 (receive / transmit power ratio) × 100... (2.1)

[0092] (Scattering index II) = (P at 15°, 30°, 45°, 60°, 75°) i / P0 (total of receive / transmit power ratio) / (P at 0°, 15°, 30°, 45°, 60°, 75°) i (Total of / P0 (receive / transmit power ratio)) × 100... (2.2)

[0093] When the scattering rate I is set as d1 and the scattering rate II is set as d2, the following formula (2.3) can be used for conversion.

[0094] d2=(100d1 / (100+100d1))×100...(2.3)

[0095] Furthermore, in the above method for measuring scattering rate, the scale of the receiving angle of the transmitted wave is set to 5° intervals, and the scattering rate III is calculated by the following formula (2.4).

[0096] (Scattering index III) = (P at 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°) i / P0 (total of receive / transmit power ratio) / (P at 0°, 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°) i(Total of / P0 (receive / transmit power ratio)) × 100... (2.4)

[0097] The scattering rate II of the flat plate members described later in Comparative Examples 1 to 5, which are examples of members on the first main surface 2 that do not have a structural part 5 that causes the scattering of radio waves, is 0.1% to 0.2%. Therefore, as described above, "the transmitted radio waves are emitted in a scattered state" means that the scattering rate III is 1.0% or more.

[0098] It should be noted that, ideally, the scattering rate should be based on the ratio of the power obtained by adding up the power of the radio waves scattered in all three-dimensional directions at other angles relative to the power of the radio waves in the 0° direction. However, currently, due to the difficulty in measuring this technically, the scattering rate is defined as Equations (2.1), (2.2), and (2.4) above. Furthermore, based on the scattering rate defined therein, as mentioned above, "the transmitted radio waves are emitted in a scattered state" means that the scattering rate II is 1.0% or higher.

[0099] Since the sample in Comparative Example 1 did not have a protrusion, the ratio of the total power received by the receiver at 15, 30, 45, 60, and 75° to the power received by the receiver at 0°, i.e., the scattering rate, was 0.06%, meaning that the transmitted electromagnetic waves were almost completely scattered. In contrast, the scattered electromagnetic wave ratio of Example 3, which has a protrusion and will be described later, was 385.38%, indicating that the transmitted electromagnetic waves were in a scattered state.

[0100] As a mechanism by which the transmitted electromagnetic waves are emitted in a scattered state by forming a protrusion, it can be considered to be related to multiple mechanisms, but one major mechanism can be considered to be that the protrusion acts as a diffraction grating.

[0101] Therefore, taking the case where the cross-section of the convex part is rectangular as an example, we will examine it using diffraction theory. Figure 8 This is a graph showing the relationship between the transmission attenuation of the samples in Examples 4, 4.1, 4.2, 4.3, and 4.4 described below and the height of the protrusion, calculated using the above measurement method. According to... Figure 8 The maximum transmission attenuation is observed when the height of the protrusion is 3mm. As the height of the protrusion deviates from 3mm, the transmission attenuation tends to decrease.

[0102] In light diffraction, for a diffraction grating with a rectangular cross-section, let the transmittance of the 0th order light be I0 and the real part of the dielectric constant be ε. r When the height of the convex part is set as h and the wavelength is set as λ, the following relationship holds (scalar diffraction theory).

[0103]

[0104] With λ fixed at a wavelength of 3.92 mm at 76.5 GHz, I0 is εr The function of h, in the same manner as in the embodiment, uses ε r When the value is set to 2.6, the relationship between the height of the convex part and I0 is as follows: Figure 9 As shown. By Figure 9 It can also be seen that the lowest I0 is observed when the height of the protrusion is 3mm, and I0 tends to increase as the height deviates from 3mm. Here, the 0th order transmittance I0 represents the proportion of the intensity of the direct-transmitted light among all transmitted light, which can be considered to correspond to the transmission attenuation of the direct-transmitted wave in this invention. Thus, the measured... Figure 8 state and Figure 9 The theory shows a roughly approximate state, therefore it is speculated that the electromagnetic wave scatterer of the present invention is related to the scalar diffraction theory of light. Therefore, by controlling the real part ε of the dielectric constant... r With the height h of the protrusion, a suitable radio wave scatterer for the frequency of the radio wave being the object can be obtained.

[0105] Furthermore, according to Bragg's law, the direction (angle) of the scattered wave produced by diffraction is determined by the period of the convex part (the length of the sum of the width and the spacing). The diffracted waves transmitted between the convex parts form interference fringes that reinforce or weaken each other. At this time, the mutually reinforcing parts are observed in the form of scattered waves. The angle at which the transmitted electromagnetic waves reinforce or weaken each other is expressed by the following equations (4) and (5). (d: period; m: integer)

[0106] The case of mutual reinforcement: dsinθ=mλ...(4)

[0107] The case of mutual weakening: dsinθ=(m+1 / 2)λ...(5)

[0108] With λ fixed, since the only variables are the mutually reinforcing angle θ and the period d, the angle of the scattered wave changes with the period. Table 1 shows the mutual reinforcing angle of the diffracted waves, i.e., the change in the angle of the scattered wave, when the period d is changed.

[0109] Table 1

[0110]

[0111] Table 2, corresponding to Example 3 described later, shows the results of measuring the transmission attenuation of a sample with a length P of 150 mm and a width Q of 150 mm in the apparatus used for scattering rate measurement, with the receiver set at various angles of 0°, 15°, 30°, 45°, 60°, and 75°.

[0112] Table 2

[0113]

[0114] According to Table 2, the minimum angle of transmission attenuation, i.e., the angle at which the scattered wave is observed, is 30°. The width of the protrusions in the sample of Example 3 is 4 mm, and the spacing is also 4 mm, so the period d is 8, which is generally consistent with the direction of the scattered wave of 29° with d=8 in Table 1. Therefore, it is speculated that the electromagnetic wave scatterer of the present invention is also related to Bragg's law. Therefore, the spacing of the protrusions can be appropriately configured based on equations (4) and (5).

[0115] Based on the above analysis, it is hypothesized that the convex portion of the electromagnetic wave scatterer functions as a diffraction grating. Therefore, it can be assumed that by employing the following configuration, the emission of strong electromagnetic waves in a specific direction can be suppressed. As mentioned above, according to Bragg's law, when repeating a single width and interval (period), the diffracted waves reinforce each other in a specific direction. Therefore, it can be assumed that if different widths are mixed in the repeating structure with varying widths and intervals, reinforcement in a specific direction can be suppressed, and the transmission attenuation can be homogenized relative to the direction, thereby suppressing the emission of strong electromagnetic waves in that specific direction.

[0116] While these studies reference the theory of light diffraction, applying it to millimeter waves is not easy. This is because radio waves, especially millimeter waves and quasi-millimeter waves, also require consideration of their wavelengths being more than three orders of magnitude larger than visible light. For example, millimeter waves have lower rectilinearity (making them more prone to diffraction) compared to visible light, and they penetrate plastic walls, paper, and other objects more easily than visible light; therefore, these characteristics need to be taken into account during the design process.

[0117] As an example, for Figure 10 The radio wave scatterer of Embodiment 14, shown below, with a shape formed by repeating units of 2mm, 4mm, and 8mm widths at 4mm intervals, is compared with the radio wave scatterer of Embodiment 3, with a shape of 4mm width convex strips at 4mm intervals. Table 3. Figure 11 The results are shown for the samples of Example 14 and Example 3, obtained by setting the receiver at various angles of 0°, 15°, 30°, 45°, 60° and 75° and measuring the transmission attenuation according to the above measurements.

[0118] Table 3

[0119]

[0120] In the radio wave scatterer of Example 3, as described by Bragg's law, the diffracted waves reinforce each other around 30°. In contrast, in the case of radio wave scatterers of Example 14 with ridges of different widths, no mutual reinforcement in a specific direction is observed, and a uniform transmission attenuation relative to the direction can be confirmed.

[0121] Therefore, in the electromagnetic wave scatterer of the present invention, when diffraction plays a major role, by configuring it with a mixture of different widths and intervals, it is possible to achieve uniformity of the transmission attenuation relative to the direction, and to suppress strong electromagnetic waves from being emitted in a specific direction.

[0122] In the above embodiment, the protrusion 6 is a raised strip, and its cross-section spanning its long side is rectangular. However, the shape of the protrusion 6 is not limited to this and can be set to any other suitable shape. For example, its cross-sectional shape can be as follows: Figure 12 As shown, it is a triangle, and its cross-sectional shape can also be as follows. Figure 13 As shown, it is a circle. It can be considered that when the cross-sectional shape is other than a rectangle (such as a triangle or a circle), the degree of scattering becomes greater when scattering from refraction is added to the scattering produced by diffraction.

[0123] Furthermore, in the above embodiment, the protrusion 6 is a continuous protrusion in the long side direction, but it can also be a discontinuous protrusion in the long side direction. Moreover, the protrusion 6 can also be formed as a dot. Figure 14 This is a top view of an example of an electromagnetic wave scatterer in which the shape of the protrusion 6 is a regular square pyramid (with an isosceles triangle cross-section), the spacing S is set to 0, and the components are arranged in a matrix. Additionally, Figure 15 This is a top view of an example of an electromagnetic wave scatterer in which the shape of the protrusions 6 is hemispherical (with a semicircular cross-section), the spacing S is set to 0, and they are arranged in a matrix. In these examples, the protrusions 6 are arranged in a matrix, but the arrangement of the protrusions 6 is not limited to this; for example, it can be arranged in an alternating pattern or any other suitable arrangement.

[0124] In addition, the protrusion 6 can also be arranged in a matrix or in an alternating pattern with the quadrangular prisms (with rectangular cross-sections) in a dotted manner. Figure 16 This is a top view of an example of an electromagnetic wave scatterer in which the shape of the protrusion 6 is set as a regular square prism (with a rectangular cross-section) and arranged in a matrix at specified intervals S. Figure 17 This is a top view of an example of an electromagnetic wave scatterer in which the protrusion 6 is shaped as a regular square prism (with a rectangular cross-section) and arranged in an alternating pattern at specified intervals S. Additionally, Figure 18 This is a top view of an example of an electromagnetic wave scatterer in which the shape of the protrusion 6 is set as a regular hexagonal prism (the cross-sectional shape is rectangular) and arranged in a honeycomb pattern at specified intervals S.

[0125] When the convex portion 6 is a raised rib, the radio waves, due to properties similar to a diffraction grating, are mainly scattered in the direction perpendicular to the long side of the rib, and almost no scattering occurs in that direction. In contrast, when the convex portion 6 is a point, especially when it has a point-symmetric shape when viewed from above, it scatters in all directions when viewed from above. Therefore, compared to the case where the convex portion 6 is a raised rib, the radio waves can be scattered more uniformly. Furthermore, when the convex portion 6 is a point, this configuration allows for manipulation of the radio wave scattering direction. The above... Figure 16 , Figure 17 , Figure 18 The diagram illustrates the scattering directions of electromagnetic waves in the shape and configuration of the protrusions 6 described above. The right-hand diagram of each figure shows the results of electromagnetic field simulations based on the finite element method for the transmitted waves in the shape and configuration of the protrusions 6 in the left-hand diagram. In the aligned configuration, electromagnetic waves scatter in four directions to adjacent protrusions 6. In contrast, by changing the honeycomb configuration, staggered configuration, and configuration method, the scattering directions of electromagnetic waves can be increased. The more the scattering directions of electromagnetic waves increase, the lower the electromagnetic wave density per unit area, thus further suppressing the emission of strong electromagnetic waves in specific directions.

[0126] Furthermore, in the above embodiment, the protrusion 6 is formed in the form of mutually parallel protrusions, but the protrusions do not necessarily have to be formed in a mutually parallel manner. For example, they can be formed as follows: Figure 19 The wave scatterer shown in Embodiment 84 described later is formed in a serrated arrangement of raised strips, or it can be formed as follows: Figure 20 The radio wave scatterer shown in Embodiment 85 (described later) is formed with convex strips arranged radially. However, it is preferable that the convex strips are formed parallel to each other, as this simplifies the design.

[0127] Furthermore, in the above embodiment, the protrusion 6 is formed in the form of a straight ridge, but the shape of the ridge is not limited to this and can be formed in any other suitable shape. For example, it can be as follows: Figure 21 The shape shown is formed as a serrated bend, or it can be like... Figure 22 The shape shown is wavy.

[0128] In addition, when the raised strip is formed in a place where mud and dirt easily adhere, it is preferable that the long side of the raised strip is set in a direction perpendicular to the ground, so that dirt is difficult to accumulate.

[0129] Furthermore, in the above embodiments, the structural part is composed of a protrusion, but it can also be composed of a hole, or it can be composed of both a protrusion and a hole. Here, "hole" includes both a recess and a through hole.

[0130] When the protrusion is provided as described in the above embodiment, the weight of the electromagnetic wave scatterer increases only by increasing the amount of material used to manufacture the protrusion. Therefore, by providing a hole in the support portion, the increase in the weight of the electromagnetic wave scatterer can be suppressed. Figure 23 This is a top view and a cross-sectional view of an example of a structure in which the support portion of an electromagnetic wave scatterer has a hole. Similar to the electromagnetic wave scatterer in the above embodiment, the electromagnetic wave scatterer 1 is formed with: a support portion 4 having a first main surface 2 and a second main surface 3; and a structural portion 5 formed on the first main surface 2, which scatters electromagnetic waves. The structural portion 5 is composed of a plurality of protrusions 6. In this embodiment, the protrusions 6 are raised strips, all extending in the same direction and formed parallel to each other. Furthermore, cylindrical holes 7 are provided between adjacent protrusions 6. The width (diameter) of the hole 7 is V, the depth is D, and the spacing between adjacent holes 7 is arranged in a matrix shape with a distance of U. The hole 7 has a bottom with a thickness T3. Based on this configuration, it is believed, as described above, that not only can the increase in weight of the electromagnetic wave scatterer be suppressed, but also, in addition to the protrusions 6, the residual portions in the support portion 4 adjacent to the holes 7 also contribute to the scattering of incident electromagnetic waves. Furthermore, Figure 23 The central hole is cylindrical, but it does not have to be circular. For example, it can be any other suitable shape such as a triangular prism or a quadrangular prism.

[0131] It should be noted that the hole 7 can also be a through hole. For example, when the radio wave scatterer of this embodiment is applied to a cover member disposed in the bumper of a car as described in the "Background Art" section above, in order not to reduce the function of the cover member, namely the anti-fouling function (preventing contamination of the radar surface caused by mud, etc.), it is preferable to make it a bottomed hole rather than a through hole.

[0132] Furthermore, in the above embodiment, the scattering structure formed in the radio wave scatterer is formed on the first principal surface, i.e., the radio wave incident surface. However, even if the structure is formed on the second principal surface, i.e., the radio wave exiting surface, a scattering state of radio waves can still be generated. Therefore, it can be formed on the radio wave exiting surface, or on both the radio wave incident surface and the radio wave exiting surface. When protrusions are provided on both the radio wave incident surface and the radio wave exiting surface, the total height of the protrusions on both surfaces can be set within the aforementioned preferred range. When protrusions and / or apertures are formed on both the radio wave incident surface and the radio wave exiting surface, by forming protrusions and / or apertures on the radio wave exiting surface at positions opposite to the protrusions and / or apertures formed on the radio wave incident surface, it is easier to obtain a more superior transmission attenuation. Figure 24 Yes Figure 5 The electromagnetic wave scatterer shown has a convex portion formed on the electromagnetic wave emitting surface, opposite to the convex portion formed on the electromagnetic wave incident surface. The combined height of the two convex portions is equal to... Figure 5 A cross-sectional view of an example of an electromagnetic wave scatterer with the same H as the convex portion 6.

[0133] Alternatively, the shape of the protrusion can be stepped. Figure 25 This is a cross-sectional view of an example of a stepped radio wave scatterer with a two-segmented convex shape. It is believed that, based on this configuration, the upper segment, in addition to the lower segment, also contributes to the scattering of incident radio waves.

[0134] As described above, when the wavelength of the incident electromagnetic wave is set to λ, it is preferable that the height of the protrusion is 0.26λ or more, the width of the protrusion is 0.26 or more, and the spacing between the protrusions is 5.1λ or less. However, considering that the height, width, and spacing of the protrusions are equivalent to the depth, spacing, and width of the aperture, when the wavelength of the incident electromagnetic wave is set to λ, it is preferable that the height of the protrusion is 0.26λ or more, the width of the protrusion is 0.26 or more, and the spacing between the protrusions is 5.1λ or less, and / or the depth of the aperture is 0.26λ or more, the spacing between the apertures is 0.26λ or more, and the width of the aperture is 5.1λ or less.

[0135] Furthermore, the height of the protrusion and the depth of the hole are preferably designed to be in the range of 0.51λ or more, and even more preferably in the range of 0.77λ or more.

[0136] Furthermore, the width of the portion of the protrusion that rises from the first main surface and the spacing between the portions of the hole that descend from the adjacent first main surface are preferably designed to be in the range of 0.26λ or more, and even more preferably in the range of 0.51λ or more.

[0137] Furthermore, the spacing between adjacent protrusions and the width of the hole are preferably designed to be within the range of 3.10λ or less, and even more preferably within the range of 2.04λ or less. It should be noted that, as above, the spacing between adjacent protrusions is a value measured between opposing portions where the protrusions stand upright from the first main surface, and the width of the hole is a value measured between opposing portions where the hole descends from the first main surface.

[0138] Furthermore, the volume fraction of the protrusion, as described later, is preferably designed to be in the range of 3% or more, more preferably in the range of 3.8% or more, even more preferably in the range of 15% or more, even more preferably in the range of 16.7% or more, and even more preferably in the range of 25% or more. Additionally, the volume fraction of the protrusion is preferably designed to be in the range of 90% or less, more preferably in the range of 85.2% or less, even more preferably in the range of 65% or less, even more preferably in the range of 60.9% or less, even more preferably in the range of 55% or less, and even more preferably in the range of 50.0% or less.

[0139] Here, the convexity volume ratio is the ratio of the volume of the convex portion within a unit structure to the volume of the unit structure space. A unit structure is the structure within a structural unit corresponding to a single convex portion. The unit structure space is the space enclosed by the bottom surface of the unit structure, the top surface of a plane parallel to the bottom surface (distanced from the bottom surface by the maximum height of the convex portion within the unit structure), and the side surface of a plane passing through the boundary line of the bottom surface of the unit structure and perpendicular to the bottom surface of the unit structure. For example, in... Figure 26 In the case where the support portion 4 is a flat plate shape and the protrusion 6 is a point-shaped regular square pyramid with a base and a side length of W, arranged in a matrix-like configuration with intervals S for the electromagnetic wave scattering bodies 1, the unit structure 8 in... Figure 26 The shaded area is the part in the middle. The unit structure space 81 is a cuboid space with the bottom surface 83 (a square with one side length of (W+S)) of the unit structure 8 as the bottom surface and the height H of the protrusion 6 as the height.

[0140] The performance of the electromagnetic wave scatterer regarding the height, width, and spacing of the protrusions, as well as the depth, spacing, and width of the holes and the volume ratio of the protrusions, can be verified by preparing samples and evaluating them as described in the examples, or by electromagnetic field analysis simulation.

[0141] Furthermore, in the above embodiments, the case where the incident radio wave is incident perpendicularly to the main surface of the radio wave scatterer was described. However, even when the incident radio wave is incident at an angle to the main surface of the radio wave scatterer, the emitted radio wave can still be scattered. Table 4, corresponding to Example 2, shows an example of the change in transmission attenuation when the incident angle is changed, measured by the apparatus used in the scattering rate measurement for a sample with a length P of 150 mm and a width Q of 150 mm.

[0142] Table 4

[0143]

[0144] As shown in Table 4, even when the incident electromagnetic wave is incident at an angle relative to the main surface of the electromagnetic wave scattering body, the emitted electromagnetic wave can still be scattered.

[0145] In addition, in the above embodiment, the support portion is a flat plate, but the support portion may also be curved.

[0146] Furthermore, in the above embodiment, millimeter-wave radio waves were used as an example of incident radio waves, but the wavelength of the incident radio waves is not limited to millimeter waves and can be set to any other appropriate wavelength.

[0147] [Components used to attenuate radio waves]

[0148] The component of the present invention for attenuating radio waves has the above-mentioned radio wave scatterer.

[0149] Figure 27 This is one embodiment of the component for attenuating radio waves in this invention, specifically the component for attenuating radio waves described in the [Background Art] section. Figure 1 A perspective view of an embodiment of the case of the cover member 31 in the example shown.

[0150] As a component used to attenuate radio waves, the shielding component 31 is a molded body formed of a resin composition, just like the radio wave scatterer 1, and its basic structure is the same as that of the radio wave scatterer 1. Therefore, the same markings are used for the positions with the same structure as the radio wave scatterer 1, and their descriptions are omitted.

[0151] like Figure 27 As shown, the cover member 31 has a first opening 32 on its upper surface 39 and a second opening 33 on its lower surface 40, and is integrally formed into a hollow frustum pyramid shape. Furthermore, a plurality of protrusions 6 extending in the vertical direction are formed on the inner surface 35 of the side peripheral wall 34. It should be noted that the cover member 31 is typically installed with its upper surface 39 in contact with the object being mounted.

[0152] For the cover component 31, such as Figure 28A The top view is shown. Figure 28B The diagram shows its YY cross-section. Figure 28C As shown in the ZZ cross-sectional view, depending on the installation object and the size of the radar 36, its height L is typically formed to be 0.5~25cm, more preferably 1~20cm, and even more preferably 2~15cm. In addition, its length M and depth N are typically formed to be 1~50cm, more preferably 1.5~40cm, and even more preferably 3~30cm.

[0153] The cover member 31 has a plurality of protrusions 6 formed on the inner surface 35 of the side peripheral wall 34. They all extend in the vertical direction (the direction connecting the upper surface 39 and the lower surface 40) and are formed in a parallel manner. The width of the protrusions 6 decreases as it moves away from the inner surface 35, and the angle θ of the protrusions 6 relative to the inner surface 35 of the side peripheral wall 34 is an acute angle.

[0154] According to the above structure, since the inner surface 35 of the side peripheral wall 34 of the cover member 31 is formed with multiple protrusions 6 in a special shape, sufficient electromagnetic wave absorption capability can be achieved even without using multiple materials with different dielectric constants and stacking multiple layers. Therefore, after forming a component of a specific shape, it is not necessary to stack layers formed of metal materials, etc., and it can be provided in the form of a molded body. In addition, the angle θ of the protrusions 6 relative to the inner surface 35 of the side peripheral wall 34 is formed to be an acute angle, and the protrusions 6 extend in the vertical direction, so they are easy to detach from the mold, thus improving production efficiency.

[0155] It should be noted that in the above embodiment, the cover member 31 is formed as a frustum pyramid, but the overall shape is not limited to this. For example, it can also be formed as follows: Figure 29A , Figure 29B The shape shown is a frustum cone. However, it goes without saying that the overall shape is a frustum pyramid. In the case of forming a frustum cone, the shape and configuration of the multiple protrusions 6 formed on its inner surface 35 need to be designed to facilitate their removal from the mold.

[0156] Furthermore, in the above embodiment, the cover member 31 is formed as a frustum pyramid (quadrangular frustum pyramid), but it can also be an n-sided (where n is a positive integer) pyramid. In addition, the shape of the cover member 31 is not limited to a frustum pyramid, and can be flexibly formed into any suitable shape, such as a plate or a frustum pyramid that extends in the opposite direction to the direction of radar wave emission, to fit the installation object, the shape of the radar 36, etc.

[0157] Furthermore, in the above embodiment, the plurality of protrusions 6 formed on the inner surface 35 of the side peripheral wall 34 are as follows: Figure 30A As shown, the protrusions 6 are formed in a series (continuously) on the inner surface 35 of the side wall 34 in the vertical direction (the direction connecting the upper surface 39 and the lower surface 40), but the multiple protrusions 6 can also be formed intermittently. However, if the multiple protrusions 6 are formed in a series (continuously), there is a tendency for them to easily detach from the mold.

[0158] Furthermore, in the above embodiment, the plurality of protrusions 6 formed on the inner surface 35 of the side peripheral wall 34 are as follows: Figure 30B As shown, it rises from the boundary between the upper surface 39 and the side peripheral wall 34 and is formed in a series (continuously) toward the lower surface 40, but it can also be formed as follows: Figure 30C As shown, multiple protrusions 6 can rise gently from the periphery of the upper surface 39, and this rising can gradually form a curve in such a way that the upper surface 39 and the upper surface of the protrusions 6 are continuously connected. In this way, when multiple protrusions 6 are formed such that the upper surface 39 and the upper surface of the protrusions 6 are continuously connected, there is a tendency for them to detach more easily from the mold.

[0159] Furthermore, in the above embodiment, the plurality of protrusions 6 formed on the inner surface 35 of the side peripheral wall 34 are as follows: Figure 30A As shown, the ridges 6 are formed parallel to each other on the same face of the frustum of pyramids, but the plurality of ridges 6 do not necessarily have to be formed parallel to each other. For example, on each face of the side peripheral wall 34, they can be formed as described above. Figure 20 As described above, multiple protrusions 6 are arranged to gradually unfold from their upper surface 39 toward their lower surface 40, and when viewed from the lower surface 40 of the cover member 31, the multiple protrusions 6 are formed to extend radially from the upper surface 39. Alternatively, they can also be arranged as described above. Figure 19 As configured, multiple convex strips 6 are arranged in a serrated shape. However, from the perspective of easy removal from the mold, such as Figure 30A As shown, preferably, multiple protrusions 6 are formed parallel to each other on the same surface of the frustum.

[0160] Furthermore, in the above embodiment, the upper surface 39 has a first opening 32 and the lower surface 40 has a second opening 33, but the upper surface 39 may not necessarily have a first opening 32. If the upper surface 39 does not have a first opening 32, the radar 36 can be disposed inside the upper surface 39. When the radar 36 is disposed inside the cover member 31, it has the advantage of being able to simultaneously install the radar 36 and the cover member 31 on the mounting object.

[0161] In the above embodiments, the radio wave scatterer is integrally formed on the cover member to form a member for attenuating radio waves, but the radio wave scatterer, which is separate from the cover member, can also be installed on the cover member to form a member for attenuating radio waves.

[0162] Furthermore, in the above embodiment, a radar radome component was described as an example of a component used to attenuate radio waves, but the component used to attenuate radio waves is not limited to this and can be any other suitable component.

[0163] [Radar Components]

[0164] The radar assembly of the present invention has a radar mounted in the radar radome component described above.

[0165] Figure 31 This is a perspective view of one embodiment of the radar assembly of the present invention. The basic structure of the radar assembly 10 is the same as that of the radome member 31 and the radar 36 described above. Positions with the same structure as the radome member 31 and the radar 36 are marked with the same reference numerals, and their descriptions are omitted. Figure 31 As shown, radar 36 is mounted on the upper surface 39 of shroud member 31 and constitutes radar assembly 10.

[0166] [bumper]

[0167] The bumper of the present invention includes the aforementioned component for attenuating radio waves. Figure 32 This is a schematic diagram illustrating one embodiment of the bumper of the present invention. (See section [Background Art] for details.) Figure 1 The collision prevention system shown, and Figure 31 The locations of radar components with identical structures are marked with the same label, and their descriptions are omitted. For example... Figure 32 As shown, a radar assembly 10 is disposed on the chassis (not shown) inside the bumper 38 of the vehicle 11, and an electromagnetic wave attenuation plate 91, serving as a component for attenuating electromagnetic waves, is disposed on the side of the radar assembly 10. Additionally, an electromagnetic wave attenuation region 92, serving as an electromagnetic wave scatterer, is formed on the bumper 38. If an electromagnetic wave scatterer is formed on the cover component, the electromagnetic wave attenuation plate 91 and the electromagnetic wave attenuation region 92 can be omitted. Alternatively, if an electromagnetic wave scatterer is not formed on the cover component, the electromagnetic wave attenuation plate 91 and / or the electromagnetic wave attenuation region 92 may be included. The radar assembly 10 may also be mounted on the bumper 38.

[0168] [vehicle]

[0169] The vehicle of the present invention includes the aforementioned components for attenuating radio waves, radar assembly, and / or bumper.

[0170] Figure 33 This is a diagram illustrating a general embodiment of the vehicle according to the present invention. The basic configuration of the radar assembly 10 is the same as that of the radar shroud member 31 and radar 36 described above. Positions with the same configuration as those of the shroud member 31 and radar 36 are marked with the same reference numerals, and their descriptions are omitted. Figure 33 As shown, a radar assembly 10 is disposed within the bumper 38 of the vehicle 11. The radar assembly includes a radar shroud member for attenuating radio waves. The radio wave attenuation member and the radar assembly can be configured in any combination at any suitable location.

[0171] [Resin Composition]

[0172] The resin composition has resin as its main component. "Main component" refers to a component that, relative to the total weight of the resin composition, has a lower limit of 50% by weight or more, or 60% by weight or more, or 70% by weight or more, and an upper limit of 99% by weight or less, or 90% by weight or less, or 80% by weight or less.

[0173] The resin used as the main component of the resin composition is not particularly limited, but thermoplastic resins are preferred. Examples include: polyethylene, polypropylene, polyvinyl alcohol, polyethylene terephthalate, polybutylene terephthalate, ethylene-vinyl acetate copolymer resin, polystyrene, acrylonitrile-styrene resin, acrylonitrile-butadiene-styrene copolymer resin, ASA resin, AES resin, acrylic resins such as PMMA, MS resin, MBS resin, cycloolefin resins, polyacetal resins, polyamide resins, polyester resins, polycarbonate resins, polyurethane resins, liquid crystal polymers, EPDM, PPS, PEEK, PPE, polysulfone resins, polyimide resins, fluorine resins, thermoplastic elastomers, acrylic elastomers, etc. Among these, polypropylene, polystyrene, and polyamide resins are preferred. While photocurable resins such as epoxy resins and acrylic resins, and thermocurable resins such as silicone resins require a curing process, they can also be used.

[0174] The resins constituting the resin composition can be used alone or in combination. That is, when used alone, the electromagnetic wave scatterer formed from the resin composition exhibits excellent mechanical properties; when multiple resins are used in combination, an excellent balance of strength and toughness is achieved. For example, polypropylene can be combined with EPDM (ethylene propylene diene monomer rubber) when using multiple resins in combination.

[0175] Fillers can be mixed into the resin composition. Examples of fillers used in the mixture include carbon black for improving color; inorganic materials such as talc, glass fiber, and minerals for improving strength; and softeners for improving flexibility.

[0176] From the viewpoint of reinforcement and formability (injection molding, etc.), the talc used to improve the above-mentioned strength is preferably small in particle size D50, which ranges from 0.8 to 50 μm, preferably from 2 to 30 μm, and more preferably from 5 to 20 μm.

[0177] The longer the glass fiber used to improve strength, the better; however, since it will bend during processing, a length of 1-5 mm is sufficient. To further improve strength, a method is used whereby untwisted glass fiber roving is introduced into an impregnation mold, allowing molten thermoplastic resin to evenly impregnate the filaments, and then cut to the required length (typically 5-20 mm). Furthermore, while glass fibers are typically cylindrical, glass fibers with a flat cross-section can also be used to reduce deformation during molding.

[0178] The minerals used to improve strength include calcium carbonate, mica, clay, silica spheres, aluminum hydroxide, magnesium hydroxide, and titanium dioxide. From a price perspective, calcium carbonate and silica are preferred.

[0179] For the carbon black used for coloring, for example, the DBP absorption measured according to JIS K 6217 or JIS K 6221 is 100 ml / 100 g or less. Furthermore, from the viewpoint of tinting strength, carbon black with small particle size and large specific surface area is preferred, but inexpensive general-purpose carbon black can also be used.

[0180] As the aforementioned softener, there are paraffinic oils, naphthenic oils, aromatic oils, etc., but it is preferred to select a softener that has good compatibility with the resin used.

[0181] Specifically, a particularly preferred combination of resin and filler in the resin composition used in this invention includes: using polypropylene or polyethylene as the resin and talc as the reinforcing filler; or using polyamide resin as the resin and glass fiber as the reinforcing filler.

[0182] The resin composition used in this invention may contain resin, reinforcing materials, and additives other than softeners. Examples of such additives include flame retardants, impact improvers, reinforcing agents, compatibilizers, weather improvers, antioxidants, pigments, dyes, etc.

[0183] The resin composition containing the above-mentioned filler can be mixed (kneaded) using, for example, a single-shaft or multi-shaft mixer, a batch mixer such as a labo-plastomill, or a roller mixer, according to a prescribed formulation; or it can be obtained by mixing with a solvent in a dissolved or suspended state. From the viewpoint of productivity, the method of mixing using a mixer or a batch mixer is particularly preferred.

[0184] Methods for molding cover components that use the above-mentioned resin composition and are disposed in the bumper of an automobile include injection molding, compression molding, blow molding, vacuum molding, machining, molding using photocurable resin, and molding using a 3D printer.

[0185] Among the above molding methods, injection molding, which offers superior productivity, is preferred. The resin composition used in injection molding is typically mixed using a two-shaft mixer, and the mixed resin is then molded into granules. These resin granules are fed into an injection molding machine, melted, and then injected into a mold of a predetermined shape. After cooling and solidification, the molded body is obtained.

[0186] The resin composition can transmit at least 20% of radio waves incident perpendicularly to a 3 mm thick plate formed from the aforementioned resin composition.

[0187] The resin composition is designed to have a complex relative permittivity, preferably with an imaginary part ε'' of 0.1 or less, more preferably 0.07 or less, and even more preferably 0.05 or less at any frequency from 10 to 300 GHz. When the imaginary part ε'' of the relative permittivity is such a value, the resin composition can be manufactured at a lightweight and low cost without containing dielectric loss materials or magnetic loss materials. Furthermore, when the imaginary part ε'' of the relative permittivity is such a value, it is generally known that the resin composition does not absorb electromagnetic waves of the corresponding frequency.

[0188] At any frequency from 10 to 300 GHz, the real part ε' of the relative permittivity of the resin composition is preferably 2 or more and 4 or less, more preferably 2.1 or more and 3.5 or less, and even more preferably 2.2 or more and 3.0 or less.

[0189] Example

[0190] The electromagnetic wave scatterer of the present invention will be further described using the following embodiments. It should be noted that the electromagnetic wave scatterer of the present invention is not limited to these embodiments.

[0191] [Example 1]

[0192] Using a 50t vacuum press (Made by Meisho Pressure Co., Ltd., MS-VPF-50), acrylic elastomer (Made by Kuraray Co., Ltd., LA2330) granules were pressed into a 3.0mm thick flat plate at a hot plate temperature of 160°C and a pressing time of 20 seconds. The resulting flat resin molded part was then cut to create a flat support portion with a width Q of 50mm, a length P of 50mm, and a thickness T1 of 3.0mm. Next, a 2.0mm thick flat acrylic elastomer was similarly obtained and cut to create a specified number of cuboids (ribs) with a rectangular cross-section perpendicular to the long side, a height H of 2.0mm, a width W of 4.0mm, and a length of 50mm. These ribs were then attached to one surface of the support portion using double-sided adhesive tape (Made by Nitto Denko Co., Ltd., No. 5000NS), with an interval S of 4.0mm between adjacent ribs, to create an electromagnetic wave diffuser. The characteristics of the obtained electromagnetic wave scatterer are shown in Table 5-1.

[0193] [Example 2]

[0194] Except that the height H of the protrusion is set to 4.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 1. The characteristics of the obtained radio wave scatterer are shown in Table 5-1.

[0195] [Example 3]

[0196] The electromagnetic wave scatterer was prepared in the same manner as in Example 2, except that a polypropylene sheet (real part of dielectric constant 2.3, imaginary part 0.0) was used as the resin composition. The properties of the obtained electromagnetic wave scatterer are shown in Table 5-1.

[0197] [Example 4]

[0198] 100 parts by weight of polypropylene (manufactured by Polypro Corporation of Japan, EA9HD) and 7.3 parts by weight of carbon black for coloring (manufactured by Asahi Carbon Corporation, #50 (iodine adsorption capacity 23mg / g, DBP adsorption capacity 63ml / 100g)) were added into the inlet in the order of polypropylene and carbon black. The mixture was melt-blended at 200°C using a labo-plastomill (manufactured by Toyo Seiki Corporation) to prepare a resin composition.

[0199] The resin composition was removed from the labo-plastomill and pressed into a 3mm thick flat plate using a 50t vacuum press (Mingzhuang Pressure Co., Ltd., MS-VPF-50) at a hot plate temperature of 200°C and a pressing time of 20 seconds. The processed resin composition was then cut into pieces with a width Q of 50mm, a length P of 50mm, and a thickness T1 of 3.0mm to create the support portion.

[0200] Similarly, a resin composition processed into a flat plate with a thickness of 2.0 mm was obtained. This plate was then cut to create a specified number of cuboids (protrusions) with a rectangular cross-section perpendicular to the long side, a height H of 3.0 mm, a width W of 4.0 mm, and a length of 50 mm. These were then attached to one surface of the support using double-sided adhesive tape (manufactured by Nitto Denko Corporation, No. 5000NS) with an adjacent protrusion spacing S of 4.0 mm, thus creating an electromagnetic wave scattering body. The characteristics of the resulting electromagnetic wave scattering body are shown in Table 5-1.

[0201] [Example 4.1]

[0202] Except that the height H of the protrusion is set to 2.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 4. The characteristics of the resulting radio wave scatterer are shown in Table 5-1.

[0203] [Example 4.2]

[0204] Except that the height H of the protrusion is set to 2.5 mm, the electromagnetic wave scatterer is fabricated in the same manner as in Example 4. The characteristics of the resulting electromagnetic wave scatterer are shown in Table 5-1.

[0205] [Example 4.3]

[0206] Except that the height H of the protrusion is set to 4.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 4. The characteristics of the resulting radio wave scatterer are shown in Table 5-1.

[0207] [Example 4.4]

[0208] Except that the height H of the protrusion is set to 6.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 4. The characteristics of the resulting radio wave scatterer are shown in Table 5-1.

[0209] [Example 5]

[0210] Using a 50t vacuum press (Made by Meijang Pressure Co., Ltd., MS-VPF-50), the resin composition prepared in the same manner as in Example 4 was pressed and molded into a flat plate with a thickness of 3mm under the conditions of a hot plate temperature of 200°C and a pressing time of 20 seconds. The processed resin composition was then cut into pieces with a width Q of 50mm, a length P of 50mm, and a thickness T1 of 3mm to form the support portion.

[0211] Similarly, using a 50t vacuum press (Made by Meisho Pressure Co., Ltd., MS-VPF-50), the resin composition prepared in the same manner as in Example 4 was pressed and molded into a flat plate with a thickness of 5.0 mm under conditions of a hot plate temperature of 200°C and a pressing time of 20 seconds. As a protrusion (protrusion strip), two sheets of resin composition with a thickness of 5.0 mm were glued together and cut to form a matrix of regular square pyramids with a height H of 9.0 mm and one side W of the bottom surface of 9.0 mm, arranged with an interval S of 0.0 mm between adjacent pyramids. Double-sided tape (Made by Nitto Denko Co., Ltd., No. 5000NS) was used to attach it to one surface of the support to create an electromagnetic wave scatterer. The characteristics of the obtained electromagnetic wave scatterer are shown in Table 5-1.

[0212] [Example 6]

[0213] Except that the height H of the protrusion is set to 1.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 1. The characteristics of the resulting radio wave scatterer are shown in Table 5-1.

[0214] [Example 7]

[0215] Except that the height H of the protrusion is set to 3.0 mm, the width W of the protrusion is set to 1.0 mm, and the interval S between adjacent protrusions is set to 2.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 1. The characteristics of the obtained radio wave scatterer are shown in Table 5-1.

[0216] [Example 8]

[0217] Except that the height H of the protrusions is set to 3.0 mm, the width W of the protrusions is set to 16 mm, and the interval S between adjacent protrusions is set to 12 mm, the radio wave scatterer is fabricated in the same manner as in Example 1. The characteristics of the obtained radio wave scatterer are shown in Table 5-2.

[0218] [Example 9]

[0219] Except that the height H of the protrusions is set to 3.0 mm and the spacing S between adjacent protrusions is set to 20 mm, the radio wave scatterer is fabricated in the same manner as in Example 1. The characteristics of the resulting radio wave scatterer are shown in Table 5-2.

[0220] [Example 10]

[0221] As the protrusion, a Φ12.7mm polypropylene sphere (1-6602-06, sold by Asone Corporation) was cut in half to create a hemisphere with an arc cross-section, a height of 6.4mm, and a width of 12.7mm. On one surface of a flat polypropylene support portion with a width Q of 50mm, a length P of 50mm, and a thickness T1 of 3.0mm, prepared in Example 3, the hemispheres were arranged in a matrix on the support portion with an interval S of 0.0mm between adjacent hemispheres, and then bonded together using double-sided adhesive tape (manufactured by Nitto Denko Corporation, No. 5000NS) to create an electromagnetic wave scatterer. The characteristics of the resulting electromagnetic wave scatterer are shown in Table 5-2.

[0222] [Example 11]

[0223] This embodiment corresponds to Figure 23 The implementation method is as follows: A sheet of polypropylene (real part of dielectric constant 2.3, imaginary part 0.0) with a thickness of 2.4 mm is cut into strips to create a flat support portion with a width Q of 50 mm, a length P of 50 mm, and a thickness D of 2.4 mm. Through holes of Φ8 are drilled in the support portion at 3.0 mm intervals U in a matrix pattern on the entire surface of the support portion using a hole punch. Next, a sheet of polypropylene (real part of dielectric constant 2.3, imaginary part 0.0) with a thickness of 2.0 mm is cut to create a specified number of cuboids with a rectangular cross-sectional shape, a height H of 2.0 mm, a width W of 2.0 mm, and a length of 50 mm, in a direction perpendicular to the long side. These cuboids are attached to one surface of the support portion using double-sided adhesive tape (manufactured by Nitto Denko Corporation, No. 5000NS) such that the interval S between adjacent protrusions is 9.0 mm and the protrusions do not overlap with the through holes. Next, a polypropylene plate (real part of dielectric constant 2.3, imaginary part 0.0) was cut to produce a flat plate component with a width Q of 50 mm, a length P of 50 mm, and a thickness T3 of 1.0 mm. This component was then attached to the other surface of the support using double-sided adhesive tape (manufactured by Nitto Denko Corporation, No. 5000NS) to create an electromagnetic wave scatterer. The characteristics of the resulting electromagnetic wave scatterer are shown in Table 5-2.

[0224] [Example 12]

[0225] A sheet of nylon 6 (real part 3.5, imaginary part 0.065) with a thickness of 1.0 mm was cut into strips to create a flat support portion with a width Q of 50 mm, a length P of 50 mm, and a thickness T1 of 1.0 mm. Next, as protrusions (ribs), a specified number of cuboids with a rectangular cross-section, a height H of 1.0 mm, a width W of 4.0 mm, and a length of 50 mm were created by cutting a sheet of nylon 6 (real part 3.5, imaginary part 0.0) with a thickness of 1.0 mm. These cuboids were then attached to one surface of the support portion using double-sided adhesive tape (manufactured by Nitto Denko, No. 5000NS) with a spacing S of 4.0 mm between adjacent ribs, thus creating an electromagnetic wave scatterer. The characteristics of the resulting electromagnetic wave scatterer are shown in Table 5-2.

[0226] [Example 13]

[0227] Except that the height H of the protrusion is set to 2.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 12. The characteristics of the resulting radio wave scatterer are shown in Table 5-2.

[0228] [Example 14]

[0229] Similar to Example 2, a flat support portion with a width Q of 50 mm, a length P of 50 mm, and a thickness T1 of 3.0 mm was fabricated. Next, as protrusions (ribs), a 4.0 mm thick polypropylene plate (real part of dielectric constant 2.3, imaginary part 0.0) was cut to create a predetermined number of cuboids with a rectangular cross-sectional shape perpendicular to the long side direction, having a height H of 4.0 mm, a width W of 2.0 mm, and a length of 50 mm; cuboids with a height H of 4.0 mm, a width W of 4.0 mm, and a length of 50 mm; and cuboids with a height H of 4.0 mm, a width W of 8.0 mm, and a length of 50 mm. Using double-sided tape (manufactured by Nitto Denko Corporation, No. 5000NS), these were attached to one surface of the support portion in a repeating pattern, with ribs of widths of 2.0 mm, 4.0 mm, and 8.0 mm spaced 4.0 mm apart, to create an electromagnetic wave scatterer. The characteristics of the obtained electromagnetic wave scatterers are shown in Table 5-2.

[0230] [Example 15]

[0231] Except that the width W of the protrusion is set to 2.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 3. The characteristics of the resulting radio wave scatterer are shown in Table 6-1.

[0232] [Example 16]

[0233] Except that the height H of the protrusion is set to 2.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 3. The characteristics of the resulting radio wave scatterer are shown in Table 6-1.

[0234] [Example 17]

[0235] Except that the height H of the protrusion is set to 3.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 3. The characteristics of the resulting radio wave scatterer are shown in Table 6-1.

[0236] [Example 18]

[0237] Except that the height H of the protrusion is set to 5.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 3. The characteristics of the resulting radio wave scatterer are shown in Table 6-1.

[0238] [Example 19]

[0239] Except that the height H of the protrusion is set to 7.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 3. The characteristics of the resulting radio wave scatterer are shown in Table 6-1.

[0240] [Example 20]

[0241] Except that the height H of the protrusion is set to 3.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 12. The characteristics of the resulting radio wave scatterer are shown in Table 6-1.

[0242] [Example 21]

[0243] Except that the height H of the protrusion is set to 9.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 3. The characteristics of the resulting radio wave scatterer are shown in Table 6-1.

[0244] [Example 22]

[0245] Except that the height H of the protrusion is set to 12 mm, the electromagnetic wave scatterer is fabricated in the same manner as in Example 3. The characteristics of the resulting electromagnetic wave scatterer are shown in Table 6-1.

[0246] [Example 23]

[0247] Except that the width W of the protrusion is set to 1.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 3. The characteristics of the resulting radio wave scatterer are shown in Table 6-1.

[0248] [Example 24]

[0249] Except that the height H of the protrusion is set to 3.0 mm and the width W of the protrusion is set to 16 mm, the radio wave scatterer is fabricated in the same manner as in Example 2. The characteristics of the obtained radio wave scatterer are shown in Table 6-1.

[0250] [Example 25]

[0251] Except that the width W of the protrusion is set to 16 mm, the radio wave scatterer is fabricated in the same manner as in Example 3. The characteristics of the resulting radio wave scatterer are shown in Table 6-1.

[0252] [Example 26]

[0253] Except that the spacing S between adjacent convex strips is set to 20 mm, the radio wave scatterer is fabricated in the same manner as in Example 4. The characteristics of the resulting radio wave scatterer are shown in Table 6-2.

[0254] [Example 27]

[0255] Except that the interval S between adjacent convex strips is set to 20 mm, the radio wave scatterer is fabricated in the same manner as in Example 3. The characteristics of the resulting radio wave scatterer are shown in Table 6-2.

[0256] [Example 28]

[0257] Except that the height H of the protrusion is set to 2.0 mm, the width W of the protrusion is set to 1.0 mm, and the interval S between adjacent protrusions is set to 1.0 mm, the radio wave scatterer is manufactured in the same manner as in Example 12. The characteristics of the obtained radio wave scatterer are shown in Table 6-2.

[0258] [Example 29]

[0259] Except that the spacing S between adjacent ridges is set to 12 mm, the radio wave scatterer is fabricated in the same manner as in Example 28. The characteristics of the resulting radio wave scatterer are shown in Table 6-2.

[0260] [Example 30]

[0261] Except that the width W of the protrusion is set to 12 mm, the radio wave scatterer is fabricated in the same manner as in Example 28. The characteristics of the resulting radio wave scatterer are shown in Table 6-2.

[0262] [Example 31]

[0263] Except that the width W of the protrusions is set to 12 mm and the spacing S between adjacent protrusions is set to 12 mm, the radio wave scatterer is fabricated in the same manner as in Example 28. The characteristics of the resulting radio wave scatterer are shown in Table 6-2.

[0264] [Example 32]

[0265] Except that the height H of the protrusion is set to 6.0 mm, the width W of the protrusion is set to 1.0 mm, and the interval S between adjacent protrusions is set to 1.0 mm, the radio wave scatterer is manufactured in the same manner as in Example 3. The characteristics of the obtained radio wave scatterer are shown in Table 6-2.

[0266] [Example 33]

[0267] Except that the spacing S between adjacent protrusions is set to 12 mm, the radio wave scatterer is fabricated in the same manner as in Example 32. The characteristics of the resulting radio wave scatterer are shown in Table 6-2.

[0268] [Example 34]

[0269] Except that the width W of the protrusion is set to 12 mm, the radio wave scatterer is fabricated in the same manner as in Example 32. The characteristics of the resulting radio wave scatterer are shown in Table 6-2.

[0270] [Example 35]

[0271] Except that the width W of the protrusions is set to 12 mm and the spacing S between adjacent protrusions is set to 12 mm, the radio wave scatterer is fabricated in the same manner as in Example 32. The characteristics of the resulting radio wave scatterer are shown in Table 6-2.

[0272] [Example 36]

[0273] Similar to Example 12, a flat support portion with a width Q of 50 mm, a length P of 50 mm, and a thickness T1 of 3.0 mm was fabricated. Next, a plate-shaped nylon 6 sheet with a thickness of 2.0 mm (real part of dielectric constant 3.5, imaginary part 0.065) was cut to create a regular square prism with a height H of 2.0 mm and a length W of 1.0 mm on one side of the bottom surface. These prisms were arranged in a matrix on one surface of the support portion, with adjacent square prisms spaced S by 1.0 mm, and then bonded together using double-sided adhesive tape (manufactured by Nitto Denko Corporation, No. 5000NS) to create an electromagnetic wave scatterer. The characteristics of the resulting electromagnetic wave scatterer are shown in Table 6-3.

[0274] [Example 37]

[0275] Except that the spacing S between adjacent regular square prisms is set to 12 mm, the radio wave scatterer is fabricated in the same manner as in Example 36. The characteristics of the resulting radio wave scatterer are shown in Table 6-3.

[0276] [Example 38]

[0277] Except that the width W of the regular square prism is set to 12 mm, the radio wave scatterer is fabricated in the same manner as in Example 36. The characteristics of the obtained radio wave scatterer are shown in Table 6-3.

[0278] [Example 39]

[0279] Except that the width W of the regular square prism is set to 12 mm and the spacing S between adjacent regular square prisms is set to 12 mm, the radio wave scatterer is fabricated in the same manner as in Example 36. The characteristics of the obtained radio wave scatterer are shown in Table 6-3.

[0280] [Example 40]

[0281] As the support, a flat polypropylene sheet (real part of dielectric constant 2.3, imaginary part 0.0) with a width Q of 50 mm, a length P of 50 mm, and a thickness T1 of 3.0 mm, the same as in Example 3, was used. In the fabrication of the regular square prism, a polypropylene plate with a thickness of 6.0 mm (real part of dielectric constant 2.3, imaginary part 0.0) was used, and the height H of the regular square prism was set to 6.0 mm. Otherwise, the radio wave scatterer was fabricated in the same manner as in Example 36, and the characteristics of the obtained radio wave scatterer are shown in Table 6-3.

[0282] [Example 41]

[0283] Except that the spacing S between adjacent regular square prisms is set to 12 mm, the radio wave scatterer is fabricated in the same manner as in Example 40. The characteristics of the resulting radio wave scatterer are shown in Table 6-3.

[0284] [Example 42]

[0285] Except that the width W of the regular square prism is set to 12 mm, the radio wave scatterer is fabricated in the same manner as in Example 40. The characteristics of the obtained radio wave scatterer are shown in Table 6-3.

[0286] [Example 43]

[0287] Except that the width W of the regular square prism is set to 12 mm and the spacing S between adjacent regular square prisms is set to 12 mm, the radio wave scatterer is fabricated in the same manner as in Example 40. The characteristics of the obtained radio wave scatterer are shown in Table 6-3.

[0288] [Example 44]

[0289] Similar to Example 12, a flat support portion with a width Q of 50 mm, a length P of 50 mm, and a thickness T1 of 3.0 mm was fabricated. Next, a plate-shaped nylon 6 sheet with a thickness of 2.0 mm (real part of dielectric constant 3.5, imaginary part 0.065) was cut to create a specified number of triangular prisms (protrusions) with a cross-sectional shape of isosceles triangles perpendicular to the long side, a height H of 2.0 mm, a base length (width) W of 1.0 mm, and a length of 50 mm, which were used as protrusions (protrusions). These were then attached to one surface of the support portion using double-sided adhesive tape (manufactured by Nitto Denko, No. 5000NS) with a spacing S of 1.0 mm between adjacent protrusions, thus creating an electromagnetic wave scatterer. The characteristics of the resulting electromagnetic wave scatterer are shown in Table 6-4.

[0290] [Example 45]

[0291] Except that the spacing S between adjacent convex strips is set to 12 mm, the radio wave scatterer is fabricated in the same manner as in Example 44. The characteristics of the resulting radio wave scatterer are shown in Table 6-4.

[0292] [Example 46]

[0293] Except that the width W of the protrusion is set to 12 mm, the radio wave scatterer is fabricated in the same manner as in Example 44. The characteristics of the resulting radio wave scatterer are shown in Table 6-4.

[0294] [Example 45]

[0295] Except that the width W of the protrusions is set to 12 mm and the spacing S between adjacent protrusions is set to 12 mm, the radio wave scatterer is fabricated in the same manner as in Example 44. The characteristics of the resulting radio wave scatterer are shown in Table 6-4.

[0296] [Example 48]

[0297] As the support, a flat polypropylene sheet (real part of dielectric constant 2.3, imaginary part 0.0) with a width Q of 50 mm, a length P of 50 mm, and a thickness T1 of 3.0 mm, was used, as in Example 3. A polypropylene plate with a thickness of 6.0 mm (real part of dielectric constant 2.3, imaginary part 0.0) was used in the fabrication of the triangular prism, and the height H of the protrusion was set to 6.0 mm. Otherwise, the electromagnetic wave scatterer was fabricated in the same manner as in Example 44. The characteristics of the obtained electromagnetic wave scatterer are shown in Table 6-4.

[0298] [Example 49]

[0299] Except that the spacing S between adjacent convex strips is set to 12 mm, the radio wave scatterer is fabricated in the same manner as in Example 48. The characteristics of the resulting radio wave scatterer are shown in Table 6-4.

[0300] [Example 50]

[0301] Except that the width W of the protrusion is set to 12 mm, the radio wave scatterer is fabricated in the same manner as in Example 48. The characteristics of the resulting radio wave scatterer are shown in Table 6-4.

[0302] [Example 51]

[0303] Except that the width W of the protrusions is set to 12 mm and the spacing S between adjacent protrusions is set to 12 mm, the radio wave scatterer is fabricated in the same manner as in Example 48. The characteristics of the resulting radio wave scatterer are shown in Table 6-4.

[0304] [Example 52]

[0305] Except that the spacing S between adjacent protrusions is set to 2.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 28. The characteristics of the resulting radio wave scatterer are shown in Tables 6-5.

[0306] [Example 53]

[0307] Except that the spacing S between adjacent convex strips is set to 11 mm, the radio wave scatterer is fabricated in the same manner as in Example 19. The characteristics of the resulting radio wave scatterer are shown in Tables 6-5.

[0308] [Example 54]

[0309] Except that the spacing S between adjacent ridges is set to 2.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 30. The characteristics of the resulting radio wave scatterer are shown in Tables 6-5.

[0310] [Example 53]

[0311] Except that the spacing S between adjacent convex strips is set to 11 mm, the radio wave scatterer is fabricated in the same manner as in Example 31. The characteristics of the resulting radio wave scatterer are shown in Tables 6-5.

[0312] [Example 56]

[0313] Except that the spacing S between adjacent protrusions is set to 2.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 32. The characteristics of the resulting radio wave scatterer are shown in Tables 6-5.

[0314] [Example 57]

[0315] Except that the spacing S between adjacent ridges is set to 2.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 34. The characteristics of the resulting radio wave scatterer are shown in Tables 6-5.

[0316] [Example 58]

[0317] Except that the spacing S between adjacent convex strips is set to 11 mm, the radio wave scatterer is fabricated in the same manner as in Example 35. The characteristics of the resulting radio wave scatterer are shown in Tables 6-5.

[0318] [Example 59]

[0319] Except that the width W of the regular square prism is set to 2.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 36. The characteristics of the resulting radio wave scatterer are shown in Table 6-5.

[0320] [Example 60]

[0321] Except that the width W of the regular square prism is set to 2.0 and the spacing S between adjacent regular square prisms is set to 10 mm, the radio wave scatterer is fabricated in the same manner as in Example 37. The characteristics of the obtained radio wave scatterer are shown in Table 6-5.

[0322] [Example 61]

[0323] Except that the spacing S between adjacent square prisms is set to 11 mm, the radio wave scatterer is fabricated in the same manner as in Example 39. The characteristics of the resulting radio wave scatterer are shown in Tables 6-5.

[0324] [Example 62]

[0325] Except that the width W of the regular square prism is set to 2.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 40. The characteristics of the resulting radio wave scatterer are shown in Tables 6-5.

[0326] [Example 63]

[0327] Except that the width W of the regular square prism is set to 2.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 41. The characteristics of the obtained radio wave scatterer are shown in Table 6-5.

[0328] [Example 64]

[0329] Except that the spacing S between adjacent regular square prisms is set to 11 mm, the radio wave scatterer is fabricated in the same manner as in Example 43. The characteristics of the resulting radio wave scatterer are shown in Tables 6-5.

[0330] [Example 65]

[0331] Except that the spacing S between adjacent convex strips is set to 2.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 44. The characteristics of the resulting radio wave scatterer are shown in Table 6-6.

[0332] [Example 66]

[0333] Except that the spacing S between adjacent convex strips is set to 11 mm, the radio wave scatterer is fabricated in the same manner as in Example 45. The characteristics of the resulting radio wave scatterer are shown in Table 6-6.

[0334] [Example 67]

[0335] Except that the spacing S between adjacent ridges is set to 2.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 48. The characteristics of the resulting radio wave scatterer are shown in Table 6-6.

[0336] [Example 68]

[0337] Except that the spacing S between adjacent convex strips is set to 11 mm, the radio wave scatterer is fabricated in the same manner as in Example 51. The characteristics of the resulting radio wave scatterer are shown in Table 6-6.

[0338] [Example 69]

[0339] Except that the height H of the protrusion is set to 4.0 mm, the width W of the regular square prism is set to 4.0 mm, and the spacing S between adjacent regular square prisms is set to 4.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 40. The characteristics of the obtained radio wave scatterer are shown in Table 6-6.

[0340] [Example 70]

[0341] Except that the arrangement of each regular square prism is such that the side edges of adjacent regular square prisms in the inclined direction are connected, and the interval S between adjacent regular square prisms in the longitudinal and transverse directions is 4.0 mm, the radio wave scatterer is manufactured in the same manner as in Example 69. The characteristics of the obtained radio wave scatterer are shown in Table 6-6.

[0342] [Example 71]

[0343] Except that the height H of the protrusion is set to 4.0 mm and the width W of the protrusion is set to 4.0 mm, the radio wave scatterer is manufactured in the same manner as in Example 48. The characteristics of the obtained radio wave scatterer are shown in Table 6-6.

[0344] [Example 72]

[0345] Except that the height H of the protrusion is set to 4.0 mm, the width W of the protrusion is set to 4.0 mm, and the interval S between adjacent protrusions is set to 2.0 mm, the radio wave scatterer is manufactured in the same manner as in Example 48. The characteristics of the obtained radio wave scatterer are shown in Table 6-6.

[0346] [Example 73]

[0347] Except that the height H of the protrusion is set to 4.0 mm, the width W of the protrusion is set to 4.0 mm, and the interval S between adjacent protrusions is set to 3.0 mm, the radio wave scatterer is manufactured in the same manner as in Example 48. The characteristics of the obtained radio wave scatterer are shown in Table 6-6.

[0348] [Example 74]

[0349] Except that the height H of the protrusion is set to 4.0 mm, the width W of the protrusion is set to 4.0 mm, and the interval S between adjacent protrusions is set to 4.0 mm, the radio wave scatterer is manufactured in the same manner as in Example 48. The characteristics of the obtained radio wave scatterer are shown in Table 6-6.

[0350] [Example 75]

[0351] Using a 3D printer (KEYENCE, AGILISTA), UV-curable acrylic resin (real part 2.5, imaginary part 0.050 of dielectric constant) was molded into a flat plate with a width Q of 50 mm, a length P of 50 mm, and a thickness T1 of 3.0 mm to create the support portion. Similarly, using the same 3D printer, UV-curable acrylic resin was molded into a regular square pyramid with a height H of 4.0 mm and a length W of 4.0 mm on one side of the base. Double-sided tape (Nitto Denko, No. 5000NS) was used to adhere it to one surface of the support portion, ensuring a spacing S of 2.0 mm between adjacent square pyramids, thus creating an electromagnetic wave scatterer. The properties of the resulting electromagnetic wave scatterer are shown in Table 6-6.

[0352] [Example 76]

[0353] Except that the spacing S between adjacent square pyramids is set to 4.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 75. The characteristics of the resulting radio wave scatterer are shown in Table 6-6.

[0354] [Example 77]

[0355] Similar to Example 3, a flat support portion with a width Q of 50 mm, a length P of 50 mm, and a thickness T1 of 3.0 mm was fabricated. Next, a polypropylene cylinder (with a real part of dielectric constant of 2.3 and an imaginary part of 0.0) of Φ8.0 mm and a length of 50 mm was cut in half to fabricate a specified number of semi-circular cylinders with a cross-sectional shape of semi-circle perpendicular to the long side, a height H of 4.0 mm, a diameter (width) W of 8.0 mm, and a length of 50 mm, as protrusions (protrusions). These were then attached to one surface of the support portion using double-sided adhesive tape (manufactured by Nitto Denko Corporation, No. 5000NS) with an adjacent protrusion spacing S of 1.0 mm to fabricate an electromagnetic wave scatterer. The characteristics of the resulting electromagnetic wave scatterer are shown in Tables 6-7.

[0356] [Example 78]

[0357] Except that the spacing S between adjacent protrusions is set to 2.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 77. The characteristics of the resulting radio wave scatterer are shown in Tables 6-7.

[0358] [Example 79]

[0359] Except that the spacing S between adjacent convex strips is set to 3.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 77. The characteristics of the resulting radio wave scatterer are shown in Tables 6-7.

[0360] [Example 80]

[0361] Except that the spacing S between adjacent protrusions is set to 4.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 77. The characteristics of the resulting radio wave scatterer are shown in Tables 6-7.

[0362] [Example 81]

[0363] Except that Φ12.7mm polypropylene spheres (1-6602-05, sold by Asone Corporation) were used in the fabrication of the hemispheres and the arrangement of each hemisphere was set to the closest possible configuration with a spacing S of 2.0mm between each hemisphere and the surrounding 6 hemispheres, the radio wave scatterer was fabricated in the same manner as in Example 10. The characteristics of the resulting radio wave scatterer are shown in Tables 6-7.

[0364] [Example 82]

[0365] Except that the spacing S between adjacent hemispheres is set to 4.0 mm, the radio wave scatterer is fabricated in the same manner as in Example 81. The characteristics of the resulting radio wave scatterer are shown in Tables 6-7.

[0366] [Example 83]

[0367] Similar to Example 75, a flat support portion with a width Q of 50 mm, a length P of 50 mm, and a thickness T1 of 3.0 mm was fabricated. Next, using a 3D printer (KEYENCE, AGILISTA), a regular hexagonal prism with a height H of 5.0 mm and a base side length of 2.0 mm (width W of 4.0 mm) was fabricated from UV-curable acrylic resin (real part 2.5, imaginary part 0.050). On one surface of the support portion, these prisms were arranged in a honeycomb configuration with a spacing S of 2.0 mm between each prism and the surrounding six regular hexagonal prisms, and then bonded together using double-sided tape (Nitto Denko, No. 5000NS) to create an electromagnetic wave scatterer. The characteristics of the resulting electromagnetic wave scatterer are shown in Tables 6-7.

[0368] [Example 84]

[0369] This embodiment corresponds to Figure 19 The implementation method is as follows. Except that the width W of the protrusion 6 is set to 2.0 mm and the arrangement of the protrusions is as follows: Figure 19The electromagnetic wave scatterer is fabricated with a design other than a sawtooth shape. The specific configuration of the protrusions is as follows: Each protrusion has a height H of 4.0 mm, a width W of 2.0 mm, and a length of 50 mm. The eight protrusions are arranged such that one end of the leftmost protrusion roughly aligns with the corner of the support, and the distance between the ends of adjacent protrusions (measured between opposing protrusions 6 rising from the first main surface 2) is 8 mm, with the other ends of adjacent protrusions touching. In this configuration, the distance between adjacent protrusions is 4 mm relative to the midpoint of their long side. The characteristics of the resulting electromagnetic wave scatterer are shown in Table 6-8.

[0370] [Example 85]

[0371] This embodiment corresponds to Figure 20 The implementation method is as follows. Except that the width W of the protrusion 6 is set to 2.0 mm and the arrangement of the protrusions is as follows: Figure 20 A radio wave scatterer was fabricated, not in a radial configuration. The specific arrangement of the protrusions is as follows: Each protrusion has a height H of 4.0 mm, a width W of 2.0 mm, and a length of 50 mm. One protrusion is positioned on a straight line connecting the midpoint of the upper and lower edges of the support. Next, protrusions are arranged on both sides of this protrusion, with the upper ends of adjacent protrusions touching and the lower ends of adjacent protrusions spaced 8 mm apart. Furthermore, on the outer sides of each of these protrusions, protrusions are arranged with the upper ends of adjacent protrusions touching and the lower ends of adjacent protrusions spaced 8 mm apart. The characteristics of the resulting radio wave scatterer are shown in Table 6-8.

[0372] [Example 86]

[0373] This embodiment corresponds to Figure 25The implementation method is as follows. Similar to Example 3, a flat support portion with a width Q of 50 mm, a length P of 50 mm, and a thickness T1 of 3.0 mm is fabricated. Next, a 2.0 mm thick polypropylene sheet is cut to create a predetermined number of cuboids (protrusions) with a rectangular cross-sectional shape perpendicular to the long side, a height of 2.0 mm, a width of 4.0 mm, and a length of 50 mm. These are attached to one surface of the support portion using double-sided adhesive tape (manufactured by Nitto Denko Corporation, No. 5000NS) such that the spacing S between adjacent protrusions is 4.0 mm. Next, a 2.0 mm thick polypropylene sheet was cut to create a specified number of cuboids with a rectangular cross-section (2.0 mm high, 2.0 mm wide, and 50 mm long) perpendicular to the long side. These cuboids were then attached to the surface of the 4.0 mm wide cuboids using double-sided tape (made by Nitto Denko Corporation, No. 5000NS), ensuring that their centers aligned in the width direction. This process created an electromagnetic wave scatterer. The characteristics of the resulting electromagnetic wave scatterer are shown in Table 6-8.

[0374] [Example 87]

[0375] This embodiment corresponds to Figure 24 The implementation method is as follows. Except that a 2.0 mm high protrusion is attached to the other surface of the support portion at a position opposite to the protrusion attached to one surface of the support portion, the radio wave scatterer is manufactured in the same manner as in Example 16. The characteristics of the obtained radio wave scatterer are shown in Tables 6-8.

[0376] [Example 88]

[0377] Similar to Example 3, a flat support portion with a width Q of 50 mm, a length P of 50 mm, and a thickness T1 of 3.0 mm was fabricated. Next, a 4.0 mm thick polypropylene sheet was cut to create a specified number of cuboids with a rectangular cross-section perpendicular to the long side, a height H of 4.0 mm, a width W of 12 mm, and a length of 50 mm. Three of these cuboids were then bonded together using double-sided tape (Nitto Denko Corporation, No. 5000NS) to create a specified number of cuboids with a height H of 12 mm, a width W of 12 mm, and a length of 50 mm as protrusions (ribs). These were then bonded to one surface of the support portion using double-sided tape (Nitto Denko Corporation, No. 5000NS), with an interval S of 12 mm between adjacent ribs, thus creating an electromagnetic wave scattering body. The characteristics of the resulting electromagnetic wave scattering body are shown in Tables 6-8.

[0378] [Comparative Example 1]

[0379] A 3.0 mm thick polypropylene sheet (real part of dielectric constant 2.3, imaginary part 0.0) was cut to produce a flat plate component with a width Q of 50 mm, a length P of 50 mm, and a thickness T1 of 3.0 mm. The properties of the obtained flat plate component are shown in Table 5-2.

[0380] [Comparative Example 2]

[0381] Using a 50t vacuum press (Mingzhuang Pressure Co., Ltd., MS-VPF-50), the resin composition prepared in the same manner as in Example 4 was pressed and shaped into a flat plate with a thickness of 3.0 mm under conditions of a hot plate temperature of 200°C and a pressing time of 20 seconds. The processed resin composition was then cut into flat plate components with a width Q of 50 mm, a length P of 50 mm, and a thickness T1 of 3.0 mm. The properties of the obtained flat plate components are shown in Table 5-2.

[0382] [Comparative Example 3]

[0383] Except that an acrylic elastomer (Kuraray, LA2330) was used as the resin composition, the flat plate component was prepared in the same manner as in Comparative Example 1. The properties of the resulting flat plate component are shown in Table 5-2.

[0384] [Comparative Example 4]

[0385] A 3.0 mm thick polypropylene sheet (real part 3.5, imaginary part 0.065 of dielectric constant) was cut to produce a flat plate component with a width Q of 50 mm, a length P of 50 mm, and a thickness T1 of 3.0 mm. The properties of the obtained flat plate component are shown in Table 5-2.

[0386] [Comparative Example 5]

[0387] A 3D printer (KEYENCE, AGILISTA) was used to mold UV-curable acrylic resin (real part 2.5, imaginary part 0.050 of dielectric constant) into a flat plate with a width Q of 50 mm, a length P of 50 mm, and a thickness T1 of 3.0 mm. The properties of the resulting flat plate are shown in Table 6-8.

[0388] Table 5-1

[0389]

[0390] Table 5-2

[0391]

[0392] Table 6-1

[0393]

[0394] Table 6-2

[0395]

[0396] Table 6-3

[0397]

[0398] Table 6-4

[0399]

[0400] Table 6-5

[0401]

[0402] Table 6-6

[0403]

[0404] Table 6-7

[0405]

[0406] Table 6-8

[0407]

[0408] [evaluate]

[0409] (Dimensional measurement)

[0410] The dimensions of the radio wave scatterer, the height, width, length of the protrusions formed on the radio wave scatterer, and the spacing between adjacent protrusions are measured using a vernier scale.

[0411] (Determination of scattering rate)

[0412] The scattering rate was determined using the same method described in the section on [Radio Wave Scatterers]. Referring to JIS R1679, the transmission attenuation was measured at 60–90 GHz using a radio transceiver (EAS03, manufactured by KEYCOM) in the order shown below. The transmission attenuation was expressed as the absolute value calculated by the following formula (1).

[0413] 10Log|P i / P0|...(1) (P i (P0: Receive power, P1: Transmit power)

[0414] like Figure 6As shown in the summary, a sample holder 11, a millimeter-wave lens 12, a transmitter 9, and a receiver 10 are configured. Radio waves with a diameter of 150 mm are transmitted from the transmitter 9. With the transmitter 9 and receiver 10 configured, radio wave transmission and reception are performed without any objects placed on the sample holder 11. The state of 0 dB transmission attenuation (complete transmission of the radio wave) is used as the reference for measuring the transmission attenuation perpendicular to the surface direction of each radio wave scatterer. Next, the radio wave scatterers are placed on the sample holder 11, and the receiver is set at angles perpendicular to the surface direction of each sample and relative to the direction from the transmitter 9 towards the receiver 10 at 0°, 15°, 30°, 45°, 60°, and 75°, respectively, and radio wave transmission and reception are performed, measuring the transmission attenuation at 76.5 GHz. It should be noted that when the structure of the radio wave scatterer is a raised strip, the measurement is performed with the long side direction of the raised strip formed on its first main surface perpendicular to the amplitude direction of the electric field of the incident wave. Based on the measured values ​​of transmission attenuation at various angles of 0°, 15°, 30°, 45°, 60°, and 75°, P is calculated using the above formula (1). i / P0 (receive / transmit power ratio), and based on the calculated P... i / P0 (receive / transmit power ratio) is used to calculate scattering rate I and scattering rate II using the following equations (2.1) and (2.2).

[0415] (Scattering rate I) = (P at 15°, 30°, 45°, 60°, 75°) i / P0 (total of receive / transmit power ratio) / (P at 0°) i / P0 (receive / transmit power ratio) × 100... (2.1)

[0416] (Scattering index II) = (P at 15°, 30°, 45°, 60°, 75°) i / P0 (total of receive / transmit power ratio) / (P at 0°, 15°, 30°, 45°, 60°, 75°) i (Total of / P0 (receive / transmit power ratio)) × 100... (2.2)

[0417] When the scattering rate I is set as d1 and the scattering rate II is set as d2, the following formula (2.3) can be used for conversion.

[0418] d2=(100d1 / (100+100d1))×100...(2.3)

[0419] Furthermore, in the above method for measuring scattering rate, the scale of the receiving angle of the transmitted wave is set to 5° intervals, and the scattering rate III is calculated by the following formula (2.4).

[0420] (Scattering index III) = (P at 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°) i / P0 (total of receive / transmit power ratio) / (P at 0°, 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°) i (Total of / P0 (receive / transmit power ratio)) × 100... (2.4)

[0421] (Determination of relative permittivity and transmittance)

[0422] Figure 34 This diagram illustrates a general overview of the method for measuring reflection attenuation. First, for the flat plate components of Comparative Examples 1-4, referring to JIS R 1679, the reflection attenuation was measured at 70-90 GHz using a radio transceiver (EAS02, manufactured by KENCKER) in the sequence shown below. Figure 17 As shown in the outline, a sample holder 11 and a transmitter / receiver 13 are configured. A reference metal is placed on the sample holder 11, and radio waves are transmitted and received. The reference metal is made of stainless steel plate with a size of Φ150mm and a thickness of 2mm. At this time, a reflection attenuation of 0dB (complete reflection of radio waves) is used as a reference for measuring the transmission attenuation of the signal perpendicularly incident on the surface direction of each plate-shaped member. Then, each plate-shaped member is placed on the sample holder 11 in place of the reference metal, and radio waves are transmitted and received, and the reflection attenuation is measured.

[0423] Next, the transmission attenuation of the plate-shaped components of Comparative Examples 1 to 4 was measured using the same measurement method as described later in the section on (measurement of transmission attenuation).

[0424] Next, using the measured values ​​of reflection attenuation and transmission attenuation of the straight-through transmitted wave from the plate-shaped members of Comparative Examples 1 to 4, the transmittance was calculated as follows.

[0425] Let the impedance of air be Z0 and the relative permeability be μ. r (=μ) r '-jμ r The relative permittivity is set to ε. r (=ε) r '-jε r When the wavelength is set to λ, the material impedance Z and propagation constant γ are expressed by the following equations (6) and (7).

[0426]

[0427] When the thickness of the object is set to d, according to the above Z and γ, and according to the transmission line theory, the reflection attenuation and transmission attenuation are expressed by the following equations (8) and (9).

[0428] Transmission attenuation (dB) = 20log{2 / (A+B / Z0+CZ0+D)}...(8)

[0429] Reflection attenuation (dB) = 20log{(A+B / Z0-CZ0-D) / (A+B / Z0+CZ0+D)...(9)

[0430] Among them, A=cosh(γd), B=Zsinh(γd), C=(1 / Z)sinh(γd), D=cosh(γd).

[0431] At this time, μ r and the expected regulations ε r Substituting into equations (6) and (7), based on the obtained Z, γ and the measured thickness d, the reflection attenuation and transmission attenuation at 70~90GHz are calculated according to equations (8) and (9).

[0432] For the curves of reflection attenuation calculated from measured values, the curves of reflection attenuation calculated from equations (6), (7), and (9) above, the curves of transmission attenuation calculated from measured values, and the curves of transmission attenuation calculated from equations (6) to (8) above, curve fitting is performed using the least squares method to derive similar ε. r This is used as the relative permittivity of each plate-shaped component. Figure 35A , Figure 35B This is a graph illustrating an example of this curve fitting. The expected specified ε... r Let it be ε r ':3.50、ε r When '': 0.20, such as Figure 35A As shown, the two curves diverge, but by changing ε... r Then, the least squares method is used for curve fitting to find the ε that minimizes the error between the two curves. r For ε r ':2.73、ε r '': 0.06, at this point, the two curves are as follows Figure 35B The results match.

[0433] Using the derived ε r Substituting into equations (6) and (7) again, based on the obtained Z and γ, the transmittance (%) when the thickness d is 3 mm is calculated using the following equation (10).

[0434] Transmittance (%) = 2 / (A+B / Z0+CZ0+D)×100 ... (10)

[0435] (Calculation of transmission attenuation)

[0436] Except for the differences in the measuring device, the measuring frequency device, the diameter of the transmitted radio wave, and the measurement of only the transmission attenuation of the straight-through transmitted wave, the transmission attenuation was measured using the same measurement method as described in the (scattering rate) section above. Referring to JIS R 1679, the transmission attenuation was measured at 70–90 GHz using a radio transceiver (EASO2, manufactured by KEYCOM) in the order shown below. The transmission attenuation was expressed as the absolute value calculated by the following formula (1).

[0437] 10Log|P i / P0|...(1) (P i (P0: Receive power, P1: Transmit power)

[0438] like Figure 6 As shown in the summary, a sample holder 11, a millimeter-wave lens 12, a transmitter 9, and a receiver 10 are configured. Radio waves with a diameter of 30 mm are transmitted from the transmitter 9. With the transmitter 9 and receiver 10 configured, radio wave transmission and reception are performed without any objects placed on the sample holder 11. The state of 0 dB transmission attenuation (complete transmission of the radio wave) is used as the reference for measuring the transmission attenuation perpendicular to the surface direction of each radio wave scatterer. Next, each sample is placed on the sample holder 11 and radio wave transmission and reception are performed, and the transmission attenuation at 76.5 GHz is measured. It should be noted that, regarding the radio wave scatterer in this embodiment, the sample has a designated protrusion on a support body with a width Q of 50 mm and a length P of 50 mm. In the case of a raised strip, the measurement is performed with the long side direction of the raised strip formed on its main surface perpendicular to the amplitude direction of the electric field of the incident wave. In addition, regarding the measurement location, besides measuring the center of the test material, measurements were also taken at five locations offset to the left and right by 5 mm and 10 mm, and the average value of these measurements was evaluated.

[0439] (evaluate)

[0440] From Tables 5-1 to 5-2 and Tables 6-1 to 6-8, the following can be observed: The transmission attenuation of the straight-path transmitted wave was 0-2 dB in the comparative examples, but greater than 2.9 dB in the embodiments, which is higher than in the comparative examples. That is, in the radio wave scattering bodies of the embodiments, the straight-path transmitted wave can be effectively attenuated.

[0441] Furthermore, the following information can be obtained from Tables 5-1 to 5-2 and Tables 6-1 to 6-8: The transmission attenuation of the direct-path transmitted wave is 0 to 2 dB in each comparative example. However, when the wavelength of the incident electromagnetic wave is set to λ, the height H, width W, and spacing S of the protrusion 6 are set to 0.51λ or more and 1.5λ or less, 0.26λ or more and 3.1λ or less, and 0.51λ or more and 2.6λ or less in Examples 1 to 4.4, 8, 9, 11, 13, 14, 16 to 19, 21, 54, 57, 60, 61, 63, 69, 70, 72 to 76, and 78 to 82 (when the protrusion 6 is a raised strip, the values ​​are set to 0.51λ or more and 1.5λ or less, 0.26λ or more and 3.1λ or less, and...). Examples 1-4.4, 7, 8, 9, 11, 13, 14, 16-19, 21, 23, 33, 37, 38, 42, 46, 47, 49, 50, 33, 46, 47, 52-58, 65-68, and 78-80, where the convex portion 6 is dot-shaped, have a wavelength of 0.51λ or higher than 1.5λ, 0.51λ or higher than 3.1λ or lower, and 0.51λ or higher than 2.6λ or lower, respectively (Examples 37, 42, 59-64, 69, 70, 72-76, 81, and 82), which is 4.0 dB or higher than the comparative examples. That is, in the radio wave scatterers of each embodiment, direct-path transmission waves can be effectively attenuated.

[0442] Furthermore, Tables 5-1 to 5-2 and Tables 6-1 to 6-8 show the following: The transmission attenuation of straight-through waves is 0-2 dB in the comparative examples with a convex volume fraction of 0%. However, when the convex volume fraction is 3% or higher and 90% or lower, it can reach 5.0 dB or higher; when the convex volume fraction is 15% or higher and 65% or lower, it can reach 10.0 dB or higher; and when the convex volume fraction is 25% or higher and 50% or lower, it can reach 15.0 dB or higher. Therefore, it can be seen that in radio wave scatterers with the above-mentioned convex volume fractions, straight-through transmitted waves can sometimes be effectively attenuated.

[0443] Furthermore, Example 11 demonstrates good transmission attenuation. Therefore, it can be seen that the structure with holes in the support portion of the electromagnetic wave scatterer can suppress the increase in the weight of the electromagnetic wave scatterer and achieve good attenuation of straight-through transmitted waves.

[0444] Table 3 Figure 10 The transmission attenuation at various receiving angles in Examples 4 and 14 is shown in Table 3. Figure 10The following can be observed. In Example 4, the transmission attenuation increases at a specific receiving angle of 30°. However, in Example 14, the transmission attenuation is uniform across all directions of the receiving angle, and strong electromagnetic waves are not emitted in the specific direction, thus effectively suppressing the emission of strong electromagnetic waves. Therefore, it can be considered that by mixing different widths in the repeating structure with varying widths and intervals, mutual reinforcement in a specific direction can be suppressed, and the emission of strong electromagnetic waves can be effectively suppressed in any emission direction.

[0445] Specific embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention may be modified in addition to the configuration illustrated. Therefore, the present invention is not limited to the configuration illustrated, and its scope should be defined only by the claims and their equivalents.

[0446] Explanation of reference numerals in the attached figures

[0447] 1. Radio wave scatterer

[0448] 2 First Main Face

[0449] 3 Second Main Face

[0450] 4 Support section

[0451] 5. Structural Section

[0452] 6 convex part

[0453] 7 Hole

[0454] 8. Unit Structure

[0455] 81 Unit structural space

[0456] 83. The bottom surface of the unit structure

[0457] 10 Radar Components

[0458] 11 vehicles

[0459] 31 Cover components

[0460] H height of convex part

[0461] W width of the protrusion

[0462] The spacing of the S-shaped protrusion

[0463] Depth of D hole

[0464] U-shaped gap

[0465] V-shaped width

Claims

1. An electric wave scatterer for scattering an incident electric wave of 10 GHz to 300 GHz having a wavelength of λ, formed of a resin composition in which a resin is a main component, having two faces of one constituting an electric wave incidence face and the other constituting an emission face, constituted in such a manner that at least a part of an electric wave incident to the electric wave incidence face is transmitted through the electric wave scatterer and the electric wave transmitted through the electric wave scatterer is emitted from the emission face in a scattered state, a structure portion is formed which causes at least one of the two faces to scatter an electric wave emitted from the emission face, the structure portion includes three or more protrusions and / or three or more hole portions, a height of the three or more protrusions is 0.51λ or more and 1.5λ or less, a width of the three or more protrusions is 0.26λ or more and 3.1λ or less, and a spacing of the three or more protrusions is 0.26λ or more and 3.1λ or less, the height of the three or more protrusions is the same, the width of the three or more protrusions is the same, and the spacing of the three or more protrusions is the same for the three or more protrusions, and / or a height of the three or more hole portions is 0.51λ or more and 1.5λ or less, a width of the three or more hole portions is 0.26λ or more and 3.1λ or less, and a spacing of the three or more hole portions is 0.26λ or more and 3.1λ or less, the depth of the three or more hole portions is the same, the width of the three or more hole portions is the same, and the spacing of the three or more hole portions is the same for the three or more hole portions. The resin composition transmits at least 50% of an electric wave perpendicularly incident with respect to a flat plate of 3 mm in thickness formed of the resin composition. The resin composition has a complex relative dielectric constant, and a real part ε' of the relative dielectric constant is 2 or more and 4 or less at a frequency of the incident electric wave.

2. The electric wave scatterer according to claim 1, wherein The resin composition has a complex relative dielectric constant, and a real part ε' of the relative dielectric constant is 2 or more and 4 or less at a frequency of the incident electric wave.

3. The electric wave scatterer according to claim 1 or 2, wherein The resin composition has a complex relative dielectric constant, and a real part ε' of the relative dielectric constant is 2 or more and 4 or less at a frequency of the incident electric wave.

4. The electric wave scatterer according to claim 1 or 2, wherein 6. A member provided with the electric wave scatterer according to any one of claims 1 to 5 and used for attenuating an electric wave.

5. The electric wave scatterer according to claim 3, wherein The member for attenuating an electric wave is a molded body, and the electric wave scatterer is formed in at least a part of the molded body. The member for attenuating an electric wave is a cover member of a radar.

7. The structure of claim 6, wherein, 9. A radar assembly in which a radar is mounted on the cover member of the radar according to claim 8.

8. The structure according to claim 6 or 7, wherein 10. A bumper including the member for attenuating an electric wave according to claim 6 or 7.

11. A vehicle provided with the member according to any one of claims 6 to 8.

12. A vehicle provided with the radar assembly according to claim 9.

13. A vehicle provided with the bumper according to claim 10. ​ ​

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