WO2023013753A1 - 電磁波シールド - Google Patents

電磁波シールド Download PDF

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Publication number
WO2023013753A1
WO2023013753A1 PCT/JP2022/030030 JP2022030030W WO2023013753A1 WO 2023013753 A1 WO2023013753 A1 WO 2023013753A1 JP 2022030030 W JP2022030030 W JP 2022030030W WO 2023013753 A1 WO2023013753 A1 WO 2023013753A1
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WIPO (PCT)
Prior art keywords
electromagnetic wave
electromagnetic
wave shield
recess
shield
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2022/030030
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English (en)
French (fr)
Japanese (ja)
Inventor
悠也 松▲崎▼
一浩 福家
丈裕 宇井
京平 秋山
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nitto Denko Corp
Original Assignee
Nitto Denko Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nitto Denko Corp filed Critical Nitto Denko Corp
Priority to JP2023540421A priority Critical patent/JPWO2023013753A1/ja
Priority to KR1020237025573A priority patent/KR20240035375A/ko
Priority to CN202280011984.6A priority patent/CN116802937A/zh
Priority to EP22853171.1A priority patent/EP4270655A4/en
Priority to US18/275,065 priority patent/US12185514B2/en
Publication of WO2023013753A1 publication Critical patent/WO2023013753A1/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00—Screening of apparatus or components against electric or magnetic fields
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/42—Housings not intimately mechanically associated with radiating elements, e.g. radome
    • H01Q1/422—Housings not intimately mechanically associated with radiating elements, e.g. radome comprising two or more layers of dielectric material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/42—Housings not intimately mechanically associated with radiating elements, e.g. radome
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/027—Constructional details of housings, e.g. form, type, material or ruggedness
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/52—Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure
    • H01Q1/526—Electromagnetic shields
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
    • H01Q17/001—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems for modifying the directional characteristic of an aerial
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
    • H01Q17/008—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems with a particular shape
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00—Screening of apparatus or components against electric or magnetic fields
    • H05K9/0073—Shielding materials
    • H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding

Definitions

  • the present invention relates to electromagnetic shielding.
  • Patent Literature 1 describes a cover for a radar device of a vehicle in which disturbance of radar directivity is suppressed.
  • This radar device cover has a three-dimensional shape in which unevenness is provided on a dielectric plate.
  • the thickness of the first portion of the dielectric plate, which forms an angle with the wavefront of the electromagnetic wave transmitted and received by the radar device, is thinner than the thickness of the second portion, which is the other portion of the dielectric plate.
  • Patent Document 2 describes a side shield for a radar transceiver.
  • a non-uniform delay structure is placed over the side shields.
  • the non-uniform delay structure delays the propagating radar signal through the side shields by a variation determined by the wavelength of the radar signal and the position on the side shield through which the radar signal propagates. This directs and spreads the radar signal after propagating through the side shields.
  • This side shield has, for example, a zigzag shaped surface (see FIG. 10C). In this case, the side shields have the advantage of uniform material thickness for molding.
  • Shielding electromagnetic waves is conceivable from the perspective of preventing unnecessary reception of radio waves. From the viewpoint of reducing the weight of the electromagnetic shield capable of exhibiting such an electromagnetic shielding function, it is conceivable to form a concave portion in the electromagnetic shield.
  • the radar device cover described in Patent Document 1 has a three-dimensional shape in which the dielectric plate is provided with unevenness, the thickness of the first portion of the dielectric plate is made thinner than the thickness of the second portion of the dielectric plate. This suppresses disturbance of radar directivity.
  • the present invention provides an electromagnetic shield that is advantageous from the viewpoint of weight reduction while shielding electromagnetic waves.
  • the present invention An electromagnetic shield, A plate-shaped base having a first surface for receiving electromagnetic waves and a second surface extending along the first surface at a position away from the first surface,
  • the electromagnetic wave shield includes a dielectric
  • the first surface includes a plurality of first recesses formed at predetermined intervals in a specific direction along the first surface, and a depth of the first recess that is in contact with one end of the first recess in the specific direction. and a first solid portion having a dimension equal to or greater than the depth of the first recess in the depth direction of the first recess
  • the second surface has a plurality of second recesses alternately formed with the plurality of first recesses in the specific direction, Provides electromagnetic shielding.
  • the above electromagnetic shield is advantageous from the viewpoint of weight reduction while shielding electromagnetic waves.
  • FIG. 1A is a plan view showing an example of an electromagnetic wave shield according to the present invention
  • FIG. 1B is a cross-sectional view of the electromagnetic shield taken along line IB-IB in FIG. 1A.
  • FIG. 1C is a cross-sectional view showing a modification of the electromagnetic shield.
  • FIG. 1D is a cross-sectional view showing a modification of the electromagnetic wave shield.
  • FIG. 2 is a cross-sectional view of a member according to a reference example.
  • FIG. 3 is a diagram schematically showing a method of measuring transmission attenuation.
  • FIG. 4 is a cross-sectional view showing another example of the electromagnetic wave shield according to the present invention.
  • FIG. 5 is a cross-sectional view showing still another example of the electromagnetic wave shield according to the present invention.
  • FIG. 6 is a plan view showing still another example of the electromagnetic wave shield according to the present invention.
  • FIG. 7 is a cross-sectional view of the electromagnetic wave shield taken along line VII-VII in FIG.
  • FIG. 8 is a cross-sectional view of the electromagnetic wave shield taken along line VIII-VIII in FIG.
  • FIG. 9 is a plan view showing still another example of the electromagnetic wave shield according to the present invention.
  • the electromagnetic wave shield 10a has a plate-shaped base 5. As shown in FIGS.
  • the base 5 has a first surface 11 and a second surface 12 .
  • the first surface 11 is a surface for entering electromagnetic waves.
  • the second surface 12 extends along the first surface 11 at a distance from the first surface 11 .
  • the electromagnetic wave shield 10a contains a dielectric.
  • the first surface 11 has a plurality of first concave portions 11a and first solid portions 11b.
  • the plurality of first recesses 11 a are formed at predetermined intervals in a specific direction (X-axis direction) along the first surface 11 .
  • the first solid portion 11b includes a surface 11s that is in contact with one end 11c of the first recess 11a in the specific direction and serves as a reference for the depth of the first recess 11a.
  • the first solid portion 11b has a dimension equal to or greater than the depth D1 of the first recess 11a in the depth direction of the first recess 11a.
  • the second surface 12 has a plurality of second recesses 12a alternately formed with a plurality of first recesses 11a in a specific direction.
  • an electromagnetic wave shield is an article that can exhibit the function of attenuating the energy of electromagnetic waves.
  • the principle by which the electromagnetic shield attenuates the energy of electromagnetic waves is not limited to a specific principle.
  • the principle is based on, for example, phenomena such as reflection, transmission, absorption, diffraction, and interference associated with interactions between electromagnetic waves and electromagnetic shields, and phenomena such as scattering and diffusion of electromagnetic waves caused by these phenomena. It can be In the electromagnetic wave shield 10a, when a predetermined electromagnetic wave is incident on the first surface 11, the energy of the electromagnetic wave is attenuated.
  • FIG. 2 is a cross-sectional view of the member 30 according to the reference example.
  • the member 30 is made of, for example, the same material as that of the electromagnetic shield 10a.
  • member 30 has a first surface 31 and a second surface 32 .
  • the first surface 31 is formed with a plurality of recesses 31a
  • the second surface 32 is formed with a plurality of recesses 32a.
  • the plurality of recesses 31 a and the plurality of recesses 32 a are alternately arranged in a specific direction (X-axis direction) along the first surface 31 .
  • the member 30 is, for example, a plate material formed in a zigzag shape, and a pair of concave portions 31a adjacent to each other in a specific direction are in contact with each other.
  • the width of the portion of the member 30 corresponding to the first solid portion 11b of the electromagnetic shield 10a is substantially zero.
  • the position in the specific direction of one end of the recess formed in the first surface 31 coincides with the position in the specific direction of the bottom of the recess formed in the second surface 32 .
  • the electromagnetic waves incident on the first surface 31 are hardly shielded.
  • the electromagnetic wave shield 10a the electromagnetic waves incident on the first surface 11 are shielded.
  • the second surface 12 of the electromagnetic shield 10a is alternately formed with the plurality of first recesses 11a and the plurality of second recesses 12a, the weight of the electromagnetic shield 10a can be easily reduced.
  • the electromagnetic wave shield 10a tends to have high impact resistance.
  • the wavelength ⁇ of the electromagnetic wave incident on the electromagnetic wave shield 10a is not limited to a specific value.
  • the wavelength ⁇ is, for example, 1 mm to 30 mm.
  • both surfaces of the first solid portion 11b are, for example, parallel to each other and flat.
  • the electromagnetic shield 10a can be used, for example, as an electromagnetic shield for applications such as millimeter wave radar, millimeter wave wireless communication, and millimeter wave sensing. Devices to which the electromagnetic shield 10a is applied can be used, for example, in automobiles, wireless base stations, and the like.
  • the electromagnetic shield 10a can be used for millimeter wave radar of one frequency band selected from the group consisting of 24 GHz band, 60 GHz band, 76 GHz band, and 79 GHz band.
  • the electromagnetic wave shield 10a does not only shield electromagnetic waves of a specific wavelength, but may shield electromagnetic waves of a wide wavelength range. .
  • the substantial irradiation wavelength is 3.89 to 3.94 mm , 3.92 mm, which is the wavelength of the center frequency of 76.5 GHz, can be determined as the wavelength ⁇ to be shielded by this electromagnetic wave shield.
  • the center The wavelength of 3.79 mm at the frequency of 79 GHz can be determined as the wavelength ⁇ to be shielded by this electromagnetic wave shield.
  • the frequency of the electromagnetic waves used is 24.05 to 24.25 GHz, that is, the wavelength of the electromagnetic waves used is 12.36 to 12.47 mm.
  • 12.41 mm which is the wavelength of the center frequency of 24.15 GHz, can be determined as the wavelength ⁇ to be shielded by this electromagnetic wave shield.
  • the wavelength of the electromagnetic wave used is 4.99 to 5.00 mm.
  • 4.99 mm which is the wavelength of the center frequency of 60.05 GHz, can be determined as the wavelength ⁇ to be shielded by this electromagnetic wave shield.
  • the frequency of the electromagnetic waves used is 27 to 29.5 GHz, that is, the wavelength of the electromagnetic waves used is 10.16 to 11.10 mm
  • the center The wavelength of 10.61 mm at the frequency of 28.25 GHz can be determined as the wavelength ⁇ to be shielded by this electromagnetic wave shield.
  • the electromagnetic wave shield is sold with a description that the corresponding frequency is 70 to 90 GHz, that is, the corresponding wavelength is 3.33 to 4.28 mm, the wavelength of 3.75 mm, which is the wavelength of the center frequency of 80 GHz, is used for this electromagnetic shield. can be determined as the wavelength ⁇ to be shielded.
  • the opening width W2 of the first concave portion 11a in the specific direction is defined, for example, as the width of the outermost portion of the first concave portion 11a.
  • the first solid portion 11b may have a curved surface 11r in the vicinity of one end 11c of the first concave portion 11a.
  • the opening width W2 is determined based on the edge 11j of the curved surface 11r inside the first recess 11a.
  • the width W1 of the first solid portion 11b is also determined based on the edge 11j.
  • the depth D1 of the first concave portion 11a, the opening width W2 of the first concave portion 11a in a specific direction, and the width W1 of the first solid portion 11b in a specific direction are set within a specific range as long as the electromagnetic waves incident on the first surface 11 are shielded. value is not limited.
  • the depth D1 When the depth D1 is compared with the specific wavelength ⁇ to be shielded by the electromagnetic wave shield 10a, the depth D1 is, for example, 0.50 ⁇ to 2.10 ⁇ . According to such a configuration, electromagnetic waves incident on the first surface 11 are more likely to be shielded in a desired state.
  • the depth D1 may be 0.60 ⁇ or more, 0.70 ⁇ or more, or 0.80 ⁇ or more.
  • the depth D1 may be 2.0 ⁇ or less, 1.9 ⁇ or less, or 1.8 ⁇ or less.
  • the aperture width W2 When the aperture width W2 is compared with the specific wavelength ⁇ to be shielded by the electromagnetic wave shield 10a, the aperture width W2 is, for example, 0.50 ⁇ to 2.10 ⁇ . According to such a configuration, electromagnetic waves incident on the first surface 11 are more likely to be shielded in a desired state.
  • the aperture width W2 may be 0.60 ⁇ or more, 0.70 ⁇ or more, or 0.80 ⁇ or more.
  • the aperture width W2 may be 2.0 ⁇ or less, 1.9 ⁇ or less, or 1.8 ⁇ or less.
  • the width W1 When the width W1 is compared with the specific wavelength ⁇ to be shielded by the electromagnetic shield 10a, the width W1 is, for example, 0.20 ⁇ to 2.0 ⁇ . According to such a configuration, electromagnetic waves incident on the first surface 11 are more likely to be shielded in a desired state.
  • the width W1 may be 0.30 ⁇ or more, 0.40 ⁇ or more, or 0.50 ⁇ or more.
  • the width W1 may be 1.9 ⁇ or less, 1.8 ⁇ or less, or 1.7 ⁇ or less.
  • the ratio W1/(W1+W2) of the width W1 to the sum (W1+W2) of the width W1 and the opening width W2 is not limited to a specific value.
  • the ratio W1/(W1+W2) is, for example, 0.1 to 0.9. According to such a configuration, electromagnetic waves incident on the first surface 11 are more likely to be shielded in a desired state.
  • the ratio W1/(W1+W2) may be 0.15 or more, 0.2 or more, or 0.3 or more.
  • the ratio W1/(W1+W2) may be 0.8 or less, 0.75 or less, or 0.7 or less.
  • the first concave portion 11a extends, for example, in the plane of the first surface 11 along a direction perpendicular to the specific direction.
  • the plurality of first recesses 11a extend linearly in parallel to each other, for example, in a plan view.
  • the plurality of first recesses 11a may extend curvedly in a plan view, or may extend in a zigzag pattern.
  • the plurality of first recesses 11a may be arranged to form a square lattice, a rectangular lattice, or a square lattice.
  • the shape of each first concave portion 11a in plan view may be, for example, a polygonal shape such as a square or a regular hexagon, or may be circular.
  • the side surface of the first concave portion 11a extends perpendicularly in a specific direction toward the second surface 12, for example.
  • the side surface of the first recess 11a is parallel to the plane perpendicular to the specific direction.
  • the shape of the second recess 12a is not limited to a specific shape.
  • the second recess 12a has, for example, the same shape as the first recess 11a.
  • the depth D2 of the second recess 12a is the same as the depth D1 of the first recess 11a
  • the opening width W4 of the second recess 12a in the specific direction is the same as the opening width W2.
  • the second recess 12a may have a shape different from that of the first recess 11a.
  • the second surface 12 has, for example, a second solid portion 12b.
  • the second solid portion 12b includes a surface 12s that is in contact with one end 12c of the second recess 12a in a specific direction and serves as a reference for the depth of the second recess 12a.
  • the second solid portion 12b has a dimension equal to or greater than the depth D2 of the second recess 12b in the depth direction of the second recess 12b.
  • the second solid portion 12b has, for example, the same shape as the first solid portion 11b.
  • the width W3 of the second concave portion 12a in the specific direction is the same as the width W1. With such a configuration, it is easy to manufacture the electromagnetic wave shield 10a.
  • the opening width W4 of the second recess 12a in the specific direction is defined, for example, as the width of the outermost portion of the second recess 12a.
  • the second solid portion 11b may have a curved surface 12r in the vicinity of one end 12c of the second concave portion 11a.
  • the opening width W4 is determined based on the edge 12j of the curved surface 12r inside the second recess 12a.
  • the width W3 of the second solid portion 12b is also determined based on the edge 12j.
  • the electromagnetic wave shield 10a As shown in FIG. 1B, in the electromagnetic wave shield 10a, the first surface 11 and the second surface 12 are formed so that the unit structures 15 appear repeatedly in a specific direction.
  • the unit structure 15 is a structure including a first concave portion 11a, a second concave portion 12a, a first solid portion 11b, and a second solid portion 12b. According to such a configuration, the electromagnetic wave shield 10a tends to have uniform electromagnetic wave shielding properties in the plane.
  • the dimension of the solid portion of the electromagnetic wave shield 10a in the depth direction of the first recess 11a varies periodically in a specific direction, for example. Its dimensions are, for example, largest in the first solid portion 11b and the second solid portion 12b and smaller in the first recess 11a and the second recess 12a.
  • the dimension of the solid portion of the electromagnetic wave shield 10a in the depth direction of the first recess 11a may be constant in a specific direction.
  • a pair of the first concave portion 11a and the second concave portion 12a that are adjacent in a specific direction are formed apart from each other in the specific direction, for example. Parts of a pair of first concave portions 11a and second concave portions 12a that are adjacent in a specific direction may overlap in a specific direction.
  • the electromagnetic wave shield 10a contains a dielectric.
  • a dielectric is not limited to a specific material.
  • the electromagnetic wave shield 10a contains resin as a dielectric, for example. In this case, the manufacturing cost of the electromagnetic shield 10a is likely to be reduced.
  • the imaginary part ⁇ ′′ of the complex dielectric constant of the dielectric at at least one frequency included in the range of 10 GHz to 300 GHz is 0.1 or less.
  • the imaginary part ⁇ ′′ is preferably 0.07 or less, It is more desirably 0.05 or less, and still more desirably 0.01 or less.
  • the real part ⁇ ' of the complex dielectric constant of the resin at at least one frequency included in the range of 10 to 300 GHz is, for example, 2 or more and 4 or less.
  • the real part ⁇ ' is preferably 2.1 or more and 3.5 or less, more preferably 2.2 or more and 3.0 or less.
  • the real part ⁇ ′ may be 3.8 or less, 3.6 or less, 3.4 or less, or 3.2 or less, It may be 3.0 or less, 2.8 or less, 2.6 or less, or 2.4 or less.
  • the resin contained in the electromagnetic wave shield 10a is not limited to a specific resin.
  • the resin is, for example, a thermoplastic resin.
  • the resin include polyethylene, polypropylene, polyvinyl alcohol, polyethylene terephthalate, polybutylene terephthalate, ethylene/vinyl acetate copolymer, polystyrene, acrylonitrile styrene, acrylonitrile/butadiene/styrene copolymer, ASA resin, AES resin, PMMA, and the like.
  • Acrylic resin MS resin, MBS resin, cycloolefin resin, polyacetal resin, polyamide resin, polyester resin, polycarbonate resin, polyurethane resin, liquid crystal polymer, EPDM, PPS, PEEK, PPE, polysulfone resin, polyimide resin, fluorine resin , a thermoplastic elastomer such as an olefinic thermoplastic elastomer (TPO), or an acrylic elastomer.
  • the resin may be a thermosetting resin.
  • Thermosetting resins are, for example, epoxy resins, acrylic resins, or silicone resins.
  • the electromagnetic wave shield 10a may contain only a single type of resin, or may contain a plurality of types of resin.
  • the electromagnetic wave shield 10a may contain filler, for example.
  • the filler may be a coloring agent such as carbon black, an inorganic reinforcing agent such as talc, glass fiber, and minerals, or a softening agent.
  • the electromagnetic wave shield 10a may contain additives such as flame retardants and plasticizers.
  • the electromagnetic wave shield 10a may not contain filler. In this case, the manufacturing cost of the electromagnetic shield 10a tends to be low.
  • the electromagnetic wave shield 10a does not have a conductive part, for example. In order to shield electromagnetic waves, for example, it is conceivable to reflect electromagnetic waves by a conductive portion such as a metal film. On the other hand, the electromagnetic wave shield 10a can shield electromagnetic waves without having a conductive portion.
  • the electromagnetic wave shield 10a may be composed only of a dielectric material, or may include a conductive portion.
  • the electromagnetic wave shield 10a is, for example, a resin molded product.
  • the molding method of the electromagnetic wave shield 10a is not limited to a specific method.
  • the electromagnetic wave shield 10a can be manufactured by injection molding, press molding, blow molding, or vacuum molding.
  • the electromagnetic wave shield 10a may be manufactured by cutting or 3D printing.
  • the interaction between the electromagnetic wave shield 10a and the electromagnetic wave that occurs for shielding the electromagnetic wave is not limited to a specific interaction.
  • the electromagnetic wave shield 10 a transmits at least part of the electromagnetic wave incident toward the first surface 11 and emits the scattered electromagnetic wave from the second surface 12 .
  • the electromagnetic wave shield 10a can function as a radio wave transmission scatterer. This makes it possible to shield electromagnetic waves with a simple configuration.
  • the depth D1 of the first concave portion 11a, the opening width W2 of the first concave portion in the specific direction, and the width W1 of the first solid portion 11b in the specific direction are is determined to be emitted from the second surface 12 in a scattered state.
  • the transmission attenuation amount of the electromagnetic wave in the rectilinear direction is not limited to a specific value. It is understood that the electromagnetic waves incident on the first surface 11 are more likely to be emitted from the second surface 12 in a scattered state as the transmission attenuation amount in the rectilinear direction increases.
  • the transmission attenuation in the rectilinear direction is, for example, 2.0 dB or more, preferably 2.5 dB or more.
  • the transmission attenuation amount of the electromagnetic wave shield 10a in the rectilinear direction can be determined, for example, by measuring with reference to Japanese Industrial Standard JIS R 1679:2007. This measurement can be performed using, for example, the measurement system shown in FIG. A sample holder SH, a millimeter wave lens L, a transmitter T, and a receiver R are arranged as shown in FIG. For example, an electromagnetic wave E transmitted from a transmitter T and adjusted to a diameter (beam diameter) of 30 mm by a millimeter wave lens L is irradiated onto the sample holder SH.
  • the electromagnetic wave E is transmitted and received with nothing set on the sample holder SH, and the state of transmission attenuation of 0 dB (the entire amount of the electromagnetic wave is transmitted) is used as a reference for measuring the transmission attenuation of the perpendicular incidence to the surface direction of each sample.
  • the transmitter T and the receiver R are arranged on the same straight line in a direction perpendicular to the main surface of the sample corresponding to the first surface 11 of the electromagnetic shield 10a. Place the receiver R so that it is located at . In this state, an electromagnetic wave E having a wavelength ⁇ is transmitted and received, and the transmission attenuation amount in the rectilinear direction is measured.
  • the transmission attenuation amount is represented by the following formula (1).
  • P I is the received power and P 0 is the transmitted power.
  • Log indicates common logarithm.
  • Transmission attenuation
  • the electromagnetic wave shield 10a can function, for example, as a diffraction grating.
  • the 0th-order light transmittance I 0 in a diffraction grating having a rectangular cross section is expressed by the following equation (2) according to the scalar diffraction theory.
  • ⁇ R is the real part of the dielectric constant of the material forming the diffraction grating
  • sqrt( ⁇ R ) is the square root of ⁇ R
  • h is the height of the projections in the diffraction grating.
  • ⁇ is the wavelength of light.
  • I 0 cos 2 ( ⁇
  • the direction (scattering angle) of the scattered transmitted wave due to diffraction is determined by the period of the projections on the diffraction grating. Interference fringes are formed by the strengthening and weakening of the diffracted waves transmitted between the convex portions. In this case, it is considered that the transmitted scattered waves are observed due to the reinforcement of the diffracted waves. Consolidation between diffracted waves can be expressed by Equation (3), and destructive mutual interaction between diffracted waves can be expressed by Equation (4).
  • d is the period of the projections in the diffraction grating
  • ⁇ is the angle at which diffracted waves constructively or destructively occur
  • m is an integer of 0 or more
  • ⁇ is is the wavelength of the incident wave. It is understood that when ⁇ is constant, the scattering angle of the transmitted scattered wave can vary depending on the period of the projections on the diffraction grating. Table 1 shows an example of the relationship between the scattering angle ⁇ at which diffracted waves are strengthened and the period d.
  • d sin ⁇ m ⁇ Formula (3)
  • d sin ⁇ (m+1/2) ⁇
  • millimeter waves are less linear than visible light (easier to diffract) and more easily penetrate objects such as plastic walls and paper than visible light. A well-designed design is required.
  • the electromagnetic wave shield 10a can be changed from various points of view.
  • the electromagnetic shield 10a may be modified like the electromagnetic shield 10b shown in FIG. 4 or the electromagnetic shield 10c shown in FIG.
  • the electromagnetic shield 10b and the electromagnetic shield 10c are configured in the same manner as the electromagnetic shield 10a, except for parts that will be particularly described.
  • Components of the electromagnetic shield 10b and the electromagnetic shield 10c that are the same as or correspond to components of the electromagnetic shield 10a are denoted by the same reference numerals, and detailed description thereof is omitted.
  • the description regarding the electromagnetic shield 10a also applies to the electromagnetic shield 10b and the electromagnetic shield 10c unless technically contradictory.
  • the side surface of the first concave portion 11a is tapered toward the second surface 12.
  • a flat bottom surface is formed in the center of the first concave portion 11a in the specific direction.
  • the first concave portion 11a is formed in a wedge shape. According to such a configuration, when the electromagnetic shield 10b and the electromagnetic shield 10c are manufactured by molding, the molded product can be easily removed from the die.
  • the angle ⁇ 1 formed by the side surface of the first concave portion 11a with respect to the plane perpendicular to the specific direction is not limited to a specific value.
  • the angle ⁇ 1 is, for example, greater than 0° and 30° or less. According to such a configuration, electromagnetic waves incident on the first surface 11 are more likely to be shielded in a desired state.
  • the side surface extending straight from the bottom of the first recess 11a toward the one end 11c of the first recess 11a specifies the angle ⁇ 1.
  • the angle ⁇ 2 formed by the side surface of the second concave portion 12a with respect to the plane perpendicular to the specific direction is not limited to a specific value.
  • the angle ⁇ 2 is, for example, greater than 0° and 30° or less.
  • the angle ⁇ 2 may be the same as the angle ⁇ 1 or may be different from the angle ⁇ 1.
  • the side surface extending straight from the bottom of the second recess 12a toward the one end 12c of the second recess 12a specifies the angle ⁇ 2.
  • At least one selected from the group consisting of the electromagnetic shield 10a and the base portion 5 is, for example, an annular body and has a first surface along the axis of the annular body. 11 has a polygonal or circular perimeter. According to such a configuration, electromagnetic waves entering the first surface 11 through the space surrounded by the electromagnetic wave shield 10a can be shielded.
  • At least one of the electromagnetic wave shield 10a and the base 5 has, for example, a truncated polygonal pyramid shape. At least one of the electromagnetic wave shield 10a and the base 5 has, for example, a tubular shape having openings at positions corresponding to the upper and lower bottom surfaces of the truncated polygonal pyramid. At least one of the electromagnetic wave shield 10a and the base 5 has, for example, a first opening 51 at a position corresponding to the upper bottom surface of the truncated polygonal pyramid, and a second opening 52 at a position corresponding to the lower bottom surface.
  • the first surface 11 forms the cylindrical electromagnetic shield 10a or the inner peripheral surface of the base portion 5 .
  • the second surface 12 forms the cylindrical electromagnetic shield 10a or the outer peripheral surface of the base portion 5 .
  • the space in which electromagnetic waves can be shielded by the electromagnetic wave shield 10a tends to be widened.
  • the first opening 51 in the electromagnetic shield 10a can be used to place an antenna for transmission and reception of electromagnetic waves.
  • At least one of the electromagnetic wave shield 10a and the base 5 may have a truncated cone shape or an elliptical truncated cone shape.
  • the electromagnetic wave shield 10a has openings at positions corresponding to the upper and lower bottom surfaces of the truncated cone or the truncated elliptical cone.
  • the electromagnetic shield 10a may be modified, for example, as an electromagnetic shield 10d shown in FIG.
  • the electromagnetic shield 10d is configured in the same manner as the electromagnetic shield 10a, except for parts that are particularly described.
  • the electromagnetic wave shield 10d further includes contact portions 6, for example.
  • the contact portion 6 is a portion for contacting a member different from the electromagnetic wave shield 10d.
  • the contact portion 6 is in contact with the polygonal or circular outer periphery that is visible when the first surface 11 is viewed along the axis of the electromagnetic wave shield 10d or the base portion 5, which is an annular body. According to such a configuration, the electromagnetic wave shield 10d can be attached to another member while the contact portion 6 is in contact with another member.
  • the contact portion 6 forms, for example, a flange.
  • a radar cover 50 with an electromagnetic shield 10a or 10d can be provided.
  • the radar cover 50 can shield unnecessary electromagnetic waves traveling toward the radar. This makes it difficult for the radar to receive unnecessary radio waves.
  • the radar cover 50 is formed, for example, in the shape of a hollow truncated pyramid and has a first opening 51 and a second opening 52. Each of the first opening 51 and the second opening 52 is rectangular. The second opening 52 is larger than the first opening 51 .
  • a transmitting/receiving antenna for a radar (not shown) is arranged in the first aperture 51 .
  • a portion of the inner surface of the radar cover 50 is formed by the first surface 11 of the electromagnetic shield 10a, and a portion of the outer surface of the radar cover 50 is formed by the second surface 12 of the electromagnetic shield 10a.
  • Example 1-1 Using polypropylene (PP), a plate-shaped sample having both sides in which a plurality of recesses arranged in a specific direction were formed at predetermined intervals was obtained. Thus, a sample according to Example 1 was obtained.
  • the real part ⁇ ′ of the complex dielectric constant of PP at 77 GHz was 2.3
  • the imaginary part ⁇ ′′ of the complex dielectric constant was 0.0. was formed as the principal surface on which radio waves were incident (incident side principal surface), and the other principal surface of the sample was formed as the principal surface from which radio waves were emitted (output side principal surface).
  • the plurality of recesses on the surface and the plurality of recesses on the output-side main surface are alternately formed in a specific direction.
  • each recess had a depth of 4 mm and a width of 4 mm in a specific direction.
  • Each recess had a solid portion forming a surface that serves as a reference for the depth of the recess.
  • the dimension of the solid portion in the depth direction of the recess was 8 mm.
  • the two surfaces of this solid portion were parallel to each other.
  • the thickness of this solid portion was the maximum thickness in the sump according to Example 1.
  • the width of the solid portion in a specific direction was 4 mm. rice field.
  • the groove depth of each recess in Examples 1-2, 1-3, 1-4, 1-5, 1-6, and 1-7 is 2 mm, Adjusted to 3 mm, 5 mm, 6 mm, 7 mm, or 8 mm.
  • the dimensions in the depth direction of the recesses of the solid portions in Examples 1-2, 1-3, 1-4, 1-5, 1-6, and 1-7 are respectively , 4 mm, 6 mm, 10 mm, 12 mm, 14 mm, or 16 mm.
  • Example 2-1 Example 2-1, Example 2-2, Samples according to Examples 2-3, 2-4, 2-5, and 2-6 were obtained.
  • Example 3-1, Example 3-2, Example 3-2, and Example Samples according to Example 3-3, Example 3-4, and Example 3-5 were obtained.
  • Example 4-1, Example 4-1, and Example 4-2 and samples according to Example 4-3 were obtained.
  • Example 5 A sample according to Example 5 was produced in the same manner as in Example 1-1 except for the following points.
  • the side surface of the recess was formed so that the recess on the incident-side principal surface tapers toward the exit-side principal surface.
  • the angle formed by the side surface with respect to a plane perpendicular to the specific direction was 27°.
  • Example 6-1 and Example 6-2 Samples of Examples 6-1 and 6-2 were obtained in the same manner as in Example 1-1, except that the depth dimension of the recess of the solid portion was changed to 6 mm or 10 mm.
  • Comparative Examples 1-1 to 1-4 Samples of Comparative Examples 1-1, 1-2, 1-3, and 1-4 were obtained in the same manner as in Example 1-1, except for the following points. Both surfaces of the samples according to these comparative examples are not formed with concave portions, and the samples according to comparative examples 1-1, 1-2, 1-3, and 1-4 are, respectively, It was flat with a thickness of 2 mm, 4 mm, 6 mm, or 8 mm.
  • Example 2 A sample according to Comparative Example 2 was obtained in the same manner as in Example 1-1, except for the following points.
  • the concave portion was formed as a V-groove, and the side surface of the concave portion made an angle of 45° with respect to a plane perpendicular to the specific direction.
  • a portion corresponding to the solid portion of Example 1-1 was not formed, and the position in a specific direction of one end of the concave portion of the V-groove on the main surface on the incident side in a specific direction was located on the main surface on the emitting side.
  • each recess was 2.8 mm and the width of each recess was 5.7 mm.
  • the thickness of the sample according to Comparative Example 2 was constant at 5.7 mm.
  • the transmission attenuation in the straight direction of the sample according to each example is greater than the transmission attenuation in the straight direction of the sample according to the comparative example, and the radio waves incident on the sample according to each example are scattered well. It was suggested that it penetrated in the state where it was

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Electromagnetism (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
PCT/JP2022/030030 2021-08-05 2022-08-04 電磁波シールド Ceased WO2023013753A1 (ja)

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KR1020237025573A KR20240035375A (ko) 2021-08-05 2022-08-04 전자파 실드
CN202280011984.6A CN116802937A (zh) 2021-08-05 2022-08-04 电磁波屏蔽件
EP22853171.1A EP4270655A4 (en) 2021-08-05 2022-08-04 SHIELDING AGAINST ELECTROMAGNETIC WAVES
US18/275,065 US12185514B2 (en) 2021-08-05 2022-08-04 Electromagnetic shield

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US12553989B2 (en) * 2020-12-25 2026-02-17 Nitto Denko Corporation Radio wave scattering body, and member for attenuating radio waves comprising radio wave scattering body

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WO1994026495A1 (en) * 1993-05-06 1994-11-24 Litel Instruments Apparatus and process for the production of fine line metal traces
JP2004280050A (ja) * 2002-10-15 2004-10-07 Eastman Kodak Co 埋込み式ワイヤグリッド偏光子
JP2010230661A (ja) 2009-03-06 2010-10-14 Toyota Central R&D Labs Inc 車両のレーダ装置用カバー
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WO2021058450A1 (en) 2019-09-24 2021-04-01 Veoneer Sweden Ab A radar side-shield and a radar transceiver assembly

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EP4270655A4 (en) 2024-12-04
KR20240035375A (ko) 2024-03-15
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US12185514B2 (en) 2024-12-31
US20240164073A1 (en) 2024-05-16
EP4270655A1 (en) 2023-11-01

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