WO2024106405A1 - 電波反射体、電波反射体の作製方法、電波反射構造体、電波反射システムおよび電波反射装置 - Google Patents

電波反射体、電波反射体の作製方法、電波反射構造体、電波反射システムおよび電波反射装置 Download PDF

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Publication number
WO2024106405A1
WO2024106405A1 PCT/JP2023/040834 JP2023040834W WO2024106405A1 WO 2024106405 A1 WO2024106405 A1 WO 2024106405A1 JP 2023040834 W JP2023040834 W JP 2023040834W WO 2024106405 A1 WO2024106405 A1 WO 2024106405A1
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WIPO (PCT)
Prior art keywords
radio wave
wave reflector
reflector
radio
reflected
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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/JP2023/040834
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English (en)
French (fr)
Japanese (ja)
Inventor
泰明 井手
弾一 宮崎
博之 野本
俊夫 江南
宗宏 畠井
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Sekisui Chemical Co Ltd
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Sekisui Chemical Co Ltd
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Application filed by Sekisui Chemical Co Ltd filed Critical Sekisui Chemical Co Ltd
Priority to JP2023578798A priority Critical patent/JPWO2024106405A1/ja
Priority to CN202380078734.9A priority patent/CN120202594A/zh
Publication of WO2024106405A1 publication Critical patent/WO2024106405A1/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
    • H01Q15/14—Reflecting surfaces; Equivalent structures

Definitions

  • the present invention relates to a radio wave reflector for reflecting radio waves, a method for manufacturing a radio wave reflector, a radio wave reflecting structure, a radio wave reflecting system, and a radio wave reflecting device.
  • Patent Document 1 proposes a communication system in which a monopole antenna and a metal reflector that reflects radio waves are placed in the space under the floor inside an indoor building.
  • the reflector diffuses the radio waves radiated from the monopole antenna into the space under the floor, and prevents them from leaking from the space under the floor to the outside of the room (building) or being absorbed by the floor of the building.
  • the reflection strength of the reflected wave is greatest when it is a regular reflection, and the reflection strength of the reflected wave that deviates from the regular reflection direction is smaller. If the receiver is positioned away from the regular reflection direction, it will not be able to receive radio waves with sufficient strength for practical use. In particular, if the reflective surface of the metal reflector is flat, the reflection strength of the reflected wave in the regular reflection direction is very large, but the reflection strength of the reflected wave that deviates slightly from the regular reflection direction is very small. For this reason, if the receiver is positioned slightly away from the regular reflection direction, it may not be able to receive sufficient radio waves.
  • the present invention was made with a focus on the above-mentioned problems, and aims to provide a radio wave reflector capable of reflecting radio waves over a wide range of space, a method for manufacturing a radio wave reflector, and a radio wave reflection system.
  • the present invention includes the following subject matter:
  • a radio wave reflector having a reflective surface that reflects radio waves,
  • the reflecting surface is a curved surface that is convex toward the side where the radio wave is incident or reflected.
  • Item 2 The radio wave reflector according to item 1, wherein the curvature 1/r of the reflecting surface is 0 (1/m) ⁇ 1/r ⁇ 7.85 (1/m).
  • Item 3 The radio wave reflector according to item 1, in which the curvature 1/r of the reflecting surface is 5.00 (1/m) ⁇ 1/r ⁇ 7.85 (1/m).
  • Item 4 A conductive layer including a conductor and constituting the reflective surface, a base layer including a base material that holds the conductive layer, a protective layer including a protective material for protecting the conductive layer, and an adhesive layer including an adhesive for bonding the conductive layer and the layer including the protective material, Item 4.
  • the radio wave reflector according to any one of items 1 to 3, wherein the base material layer, the conductive layer, the adhesive layer, and the protective layer are laminated in this order.
  • the radio wave reflector according to item 4 having a flexural modulus of 0.05 GPa or more and 4 GPa or less.
  • the radio wave reflector according to any one of items 1 to 5, further comprising a holding member that holds the reflecting surface.
  • Item 7 A method for producing a radio wave reflector according to any one of items 1 to 5, comprising: A method for producing a radio wave reflector, comprising a step of curving the reflecting surface so that it becomes a convex curved surface toward the side where radio waves are incident or reflected, when the reflector is attached to an object to which the radio wave is to be reflected.
  • a method for producing a radio wave reflector according to item 6, comprising: A method for producing a radio wave reflector, comprising a step of using the holding member to hold the reflecting surface in a curved shape that is convex toward the side where the radio wave is incident or reflected, before the reflector is attached to an object to which the radio wave is to be reflected.
  • Item 9 The radio wave reflector according to any one of items 1 to 6, and an object to which the radio wave reflector is attached.
  • Item 10 A transmitter that transmits radio waves;
  • the radio wave reflector according to any one of claims 1 to 6, which reflects radio waves transmitted from the transmitter; a receiver for receiving radio waves reflected by the radio wave reflector; a rotational position adjustment device provided on the radio wave reflector and configured to rotate the radio wave reflector.
  • the rotational position adjustment device rotates the radio wave reflector around a convex apex of the radio wave reflector as a center when viewed from a plane parallel to a plane including the direction of incidence and reflection of the radio wave on the reflection surface,
  • the rotation angle of the radio wave reflector is set to 0 degrees
  • the clockwise rotation direction is set to the + direction
  • the counterclockwise rotation direction is set to the - direction.
  • Item 11 The radio wave reflecting system according to item 10, wherein the position of the radio wave reflector that can be adjusted by the rotational position adjustment device is within a range of a rotation angle of ⁇ 90 degrees or more and +90 degrees or less.
  • the curvature 1/r is 4.73 (1/m)
  • the radio wave reflector is located at a position within a rotation angle range of -83 degrees or more and +83 degrees or less, Item 12.
  • the radio wave reflector according to any one of items 1 to 6, a rotational position adjustment device provided on the radio wave reflector and configured to rotate the radio wave reflector.
  • the present invention provides a radio wave reflector that reflects radio waves over a wide area of space, a method for manufacturing a radio wave reflector, and a radio wave reflection system.
  • FIG. 1 is a diagram for explaining a radio wave reflecting system having a radio wave reflector according to one embodiment of the present invention
  • 1A and 1B are diagrams showing a schematic configuration of a radio wave reflector, in which (A) is a cross-sectional view taken along line X1-X1 of (B), and (B) is a perspective view.
  • 1A is a cross-sectional view taken along line X2-X2 of FIG. 1B, showing a schematic configuration of another embodiment of a radio wave reflector;
  • FIG. 1B is a perspective view;
  • FIG. 6 is a cross-sectional view taken along line BB in FIG. 5 when the radio wave reflector is placed on a flat surface without being bent.
  • FIG. 1A and 1B show a schematic overall configuration of a radio wave reflector when the radio wave reflector is placed on a flat surface without being bent, in which (A) is a plan view and (B) is an enlarged view of part A in (A).
  • 11A to 11E are cross-sectional views showing other examples of the arrangement pattern of the conductors.
  • 13A is a cross-sectional view showing another example of a conductor
  • FIG. 13B is an enlarged view of a portion D in FIG. 13A is a cross-sectional view showing another example of a conductor
  • FIG. 13B is an enlarged view of a portion D in FIG.
  • FIG. 13B is an enlarged view of a portion D in FIG. FIG.
  • FIG. 11 is a cross-sectional view showing a schematic configuration of a radio wave reflector according to another embodiment when the radio wave reflector is placed on a flat surface without being bent.
  • FIG. 11 is a cross-sectional view showing a schematic configuration of a radio wave reflector according to another embodiment when the radio wave reflector is placed on a flat surface without being bent.
  • FIG. 1A is an explanatory diagram showing an example of application of a building material to a building
  • FIG. 1B is a plan view showing an example of application indoors.
  • FIG. 4 is an explanatory diagram of a rotation angle of a radio wave reflector.
  • FIG. 13 is a diagram showing the measurement results of Comparative Example 1.
  • FIG. 1 is a diagram showing the measurement results of Example 1.
  • FIG. 1 is a diagram showing the measurement results of Example 1.
  • FIG. 13 is a diagram showing the measurement results of Example 2.
  • FIG. 13 is a diagram showing the measurement results of Example 3.
  • FIG. 13 is a diagram showing the measurement results of Example 4.
  • FIG. 4 is an explanatory diagram of a rotation angle of a receiver.
  • FIG. 1 is a diagram showing the measurement results of Examples 5 to 10 and Comparative Example 2.
  • FIG. 1 is a diagram showing the measurement results of Examples 5 to 10 and Comparative Example 2.
  • a radio wave reflecting system 100 including a radio wave reflector 10 of the present invention is for reflecting radio waves transmitted from a transmitter 20 and propagating the radio waves toward a receiver 21.
  • the radio wave reflecting system 100 includes a transmitter 20 that transmits radio waves, a radio wave reflector 10 that has a reflecting surface 11d and reflects the radio waves transmitted from the transmitter 20, and a receiver 21 that receives the radio waves reflected by the radio wave reflector 10.
  • the radio wave reflecting system 100 may further include a rotational position adjustment device 50 (FIG. 12) that is provided on the radio wave reflector 10 and rotates the radio wave reflector 11.
  • the transmitter 20 is a communication device having a transmitting antenna capable of transmitting radio waves.
  • the receiving unit 21 is a communication device having a receiving antenna capable of receiving radio waves. Examples of the receiving unit 21 include a smartphone, a mobile phone, a tablet terminal, a notebook PC, a portable game machine, a repeater, a radio, and a television.
  • the radio wave reflector 10 and an attachment object 24 to which the radio wave reflector 10 is attached constitute a radio wave reflecting structure 101.
  • regular reflection means that when radio waves emitted from a transmitter 20 are reflected by a radio wave reflector 10, the incident angle ⁇ 1 of the incident wave is equal to the reflection angle ⁇ 2 of the reflected wave.
  • the incident angle ⁇ 1 is the angle between the incident wave traveling in the incident direction (indicated by arrow A1 in FIG. 1) when the radio wave enters the radio wave reflector 10 and the normal 22 of the reflecting surface 11d of the radio wave reflector 10
  • the reflection angle ⁇ 2 is the angle between the reflected wave traveling in the reflection direction (indicated by arrow A2 in FIG. 1) and the normal 22 of the reflecting surface 11d.
  • the normal 22 is a straight line that is perpendicular to the tangent 23 (or tangent plane) at the reflection point 11a of the reflecting surface 11d.
  • the intensity of the reflected wave is also called “reflection intensity.”
  • “Regular reflection intensity” is the reflection intensity that is the intensity at which the radio wave is reflected, and refers to the intensity of the reflected wave when the incident wave is regularly reflected.
  • “Regular reflection direction” refers to the direction in which the reflected wave travels when the radio wave is regularly reflected.
  • the “specular reflection angle” refers to the incident angle ⁇ 1 of the incident wave and the reflection angle ⁇ 2 of the reflected wave when specularly reflected.
  • the frequency of the radio wave transmitted by the transmitter 20 is 2 GHz or more and 300 GHz or less.
  • the radio wave reflector 10 has a reflective surface 11d that reflects radio waves.
  • the reflective surface 11d is a curved surface that is convex toward the side where the radio waves are incident or reflected, as shown in FIG. 1, in the so-called mounting structure.
  • the radio wave reflector 10 may be composed only of the radio wave reflecting material 11, or may be composed of the radio wave reflecting material 11 and other members such as a holding member 40 (described later). In the example shown in Figures 2(A) and 2(B), the radio wave reflector 10 is composed only of the radio wave reflecting material 11.
  • the radio wave reflecting material 11 is a laminate of a conductive layer 16 including conductors 12 and a base material layer 13 including a base material that holds the conductive layer 16.
  • Reflection surface 11d refers to the surface of the conductive layer 16 including conductors 12 that reflect radio waves on the side where radio waves are incident or reflected (also referred to as the "outside") in a cross section along a virtual plane that includes the incident direction of the incident wave by the transmitter 20 and the reflection direction along which the reflected wave received by the receiver 21 travels.
  • the virtual plane that includes the incident direction of the incident wave by the transmitter 20 and the reflection direction along which the reflected wave received by the receiver 21 travels is also referred to as the "virtual plane including the incident direction and reflection direction”.
  • the radio wave reflector 10 is curved so as to be convex toward the side where the radio waves are incident or reflected, when viewed in a cross section along an imaginary plane including the incident direction and the reflection direction, or from a plane parallel to this imaginary plane. Therefore, the reflecting surface 11d included in the radio wave reflecting material 11 is also a curved surface that is convex toward the side where the radio waves are incident or reflected. The curvature is set based on this reflecting surface 11d.
  • the reflective surface 11d refers to the outer surface of the thin film or metal plate. If the conductive layer 16 includes, for example, a linear conductor 12 and a conductor-free area 12a surrounded by the conductor 12, the reflective surface 11d refers to the surface that includes the outer surface of the conductor 12 and the conductor-free area 12a.
  • the radio wave reflecting material 11 may have a protective layer 15 containing a protective material for protecting the conductive layer 16 on the surface of the conductive layer 16 opposite to the surface on which the base layer 13 is provided, and an adhesive layer 14 containing an adhesive material for bonding the conductive layer 16 and the protective layer 15 between the conductive layer 16 and the protective layer 15. That is, the radio wave reflecting material 11 may have the base layer 13, the conductive layer 16, the adhesive layer 14, and the protective layer 15 laminated in this order.
  • the side on which the protective layer 15 is provided (the upper side in FIG. 4) is the side on which radio waves are incident or reflected (the outside).
  • the curvature of the reflective surface 11d is the same as the curvature of the outer surface of the protective layer 15.
  • the curvature 1/r of the reflecting surface 11d of the radio wave reflector 10 is preferably set to 0 (1/m) ⁇ 1/r ⁇ 7.85 (1/m).
  • the curvature 1/r of the reflecting surface 11d of the radio wave reflector 10 is defined as the reciprocal of the radius of curvature r (m) when the curve of the reflecting surface 11d of the radio wave reflector 10 is approximated to an arc at any point on the reflecting surface 11d that appears as a curve in a cross section along an imaginary plane that includes the direction of incidence and the direction of reflection.
  • the curvature 1/r of the reflecting surface 11d is preferably set to 5.00 (1/m) ⁇ 1/r ⁇ 7.85 (1/m), and more preferably 5.25 (1/m) ⁇ 1/r ⁇ 7.81 (1/m). This range of curvature is set based on Examples 9 and 10, in which the angle range was 150 degrees or more for both frequencies of 4.85 GHz and 28 GHz in Evaluation Test B described below. If the curvature of the reflecting surface 11d is within this range, radio waves can be reflected over a wide range of space.
  • the flexural modulus of the radio wave reflecting material 11 is 0.05 GPa or more and 4 GPa or less.
  • the flexural modulus is a value indicating how much bending stress a material can withstand, and is defined in JIS K7171.
  • the radio wave reflecting material 11 preferably has a Young's modulus of 0.01 GPa or more and 80 GPa or less. Young's modulus refers to the elastic modulus when a solid is stretched by applying tension in one direction, and is also called the tensile modulus of elasticity, and is defined in JIS K7161-2014. By setting the Young's modulus within the above range, the radio wave reflecting material 11 becomes easier to deform, and the radio wave reflecting material 11 can be bent within the above curvature 1/r range without breaking the radio wave reflector 10. Young's modulus is measured in accordance with JIS K7127-1999.
  • the radio wave reflector 10 only needs to have a reflective surface 11d that is a curved surface that is convex on the side where radio waves are incident or reflected when attached to an attachment object 24 such as a wall, and the shape before being attached to the attachment object 24 can be arbitrary.
  • the radio wave reflector 10 can be manufactured, for example, as follows. First, a radio wave reflecting material 11, which is a sheet-like member, is prepared. Then, when attaching to an attachment object 24 such as a wall, this radio wave reflecting material 11 (sheet-like member) is curved so that it has a curved surface that is convex on the side where radio waves are incident or reflected. In this way, the radio wave reflector 10 is manufactured.
  • the manufactured radio wave reflector 10 is attached to the attachment object 24 by an attachment means such as an adhesive. In other words, the configuration of the radio wave reflector 10 is the same before and after being attached to the attachment object 24, but the shape is different.
  • FIGs 2(A) and 2(B) show examples of a radio wave reflector 10.
  • the radio wave reflector 10 in Figures 2(A) and 2(B) is composed of a radio wave reflecting material 11.
  • the radio wave reflecting material 11 is a rectangular sheet-like member before being attached to the attachment object 24.
  • the radio wave reflecting material 11 is bent so that the opposing side edges 11b approach each other, thereby forming the radio wave reflector 10.
  • the radio wave reflector 10 thus formed i.e., the radio wave reflector 10 formed only from the radio wave reflecting material 11, has a semicircular cross-sectional shape along an imaginary plane including the direction of incidence and the direction of reflection, i.e., a cross-sectional shape along line X1-X1 shown in FIG. 2(B), as shown in FIG. 2(A), and is convex on the side where the radio waves are incident or reflected.
  • the direction perpendicular to the imaginary plane including the incident direction and the reflection direction is defined as the up-down direction
  • the direction on the imaginary plane including the incident direction and the reflection direction that includes the two opposing side edges 11b is defined as the left-right direction.
  • the radio wave reflector 10 is line-symmetrical at the center position in the left-right direction as shown in FIG. 2(A).
  • the distance L11 between the opposing side edges 11b is also called the "bottom width L11" and is set appropriately according to the size, reflection strength, etc. of the radio wave reflector 10.
  • the convex curved surface has a vertex 11c.
  • the vertex 11c of the convexity refers to the point that protrudes most toward the side where radio waves are incident or reflected relative to the base end of the reflecting surface 11d in a cross section along an imaginary plane that includes the incident and reflected directions.
  • the upper side of FIG. 2(A) is the side where radio waves are incident or reflected
  • the vertex 11c is the point that protrudes most upward from the side edge 11b, which is the base end.
  • the vertex 11c is a point that intersects with an imaginary line that is perpendicular to the left-right direction and passes through the center point of the width L11 of the base.
  • the vertex 11c extends in the up-down direction as shown in FIG. 2(B).
  • the apex 11c of the radio wave reflector 10 may be bent so that it extends diagonally relative to the up-down or left-right direction.
  • a convex curved surface refers to a curved surface with a central portion that protrudes to one side, and may be, for example, a semicircular, semielliptical, or any shape along a conic section in a cross section along an imaginary plane that includes the direction of incidence and the direction of reflection.
  • the overall shape may also be a hemisphere or semiellipsoid.
  • a sheet-like member refers to a member whose side has a length in the vertical or horizontal direction that is sufficiently greater than its thickness when viewed in a plane, for example, a length in the vertical or horizontal direction that is 10 times or more the thickness.
  • the radio wave reflecting material 11 when distributed in the market, i.e., before being attached to a wall or the like, is a rectangular sheet-like member, but this sheet-like member may also be wound into a roll.
  • the space between the convex radio wave reflector 10 and the mounting object 24, such as a wall, may be filled with a filler material made of resin or the like.
  • a holding member 40 (described below) as shown in FIG. 3 may first be attached to the mounting object 24, such as a wall, and the radio wave reflecting material 11 may be attached to the convex outer peripheral surface 40a of the holding member 40.
  • the radio wave reflector 10 may include a radio wave reflecting material 11 and a holding member 40 that holds the curved surface of the reflecting surface 11d of the radio wave reflecting material 11.
  • the holding member 40 is a base having an outer peripheral surface 40a with a convex cross section.
  • the convex shape of the outer peripheral surface 40a of the base corresponds to the curved surface of the reflecting surface 11d of the radio wave reflecting material 10, and by attaching the radio wave reflecting material 11 to the outer peripheral surface 40a of the base, a radio wave reflector 10 is formed that holds a curved surface that is convex on the side of the reflecting surface 11d where radio waves are incident or reflected.
  • the base is a plate-shaped base main body 41 on one side of which a semi-cylindrical mounting portion 42 is provided, and the radio wave reflecting material 11 is attached to the outer peripheral surface 40a of the mounting portion 42.
  • the base as the holding member 40 is not limited to this, and may be a member having any shape, such as a columnar or plate-shaped member bent, as long as it has a convex outer peripheral surface 40a whose cross section corresponds to the shape of the reflecting surface 11d so that the curved surface of the reflecting surface 11d of the radio wave reflecting material 11 can be held.
  • the holding member 40 does not have to be a base, and for example, a non-flexible convex layer may be provided on one side of the radio wave reflecting material 11 as the holding member 40, so that the curved surface of the reflecting surface 11d of the radio wave reflecting material 11 can be held.
  • the holding member 40 may also be used as at least one of the base layer 13, adhesive layer 14, and protective layer 15 included in the radio wave reflecting material 11.
  • the base layer 13, adhesive layer 14, and protective layer 15 are formed in a convex shape and are non-flexible, so that the curved surface of the reflecting surface 11d is held by the radio wave reflector 10 as a whole.
  • the method of manufacturing the radio wave reflector 10 shown in Figures 3(A) and 3(B) includes a step of holding the reflective surface 11d of the radio wave reflector 11 with a holding member 40 before mounting it on the mounting object 24, i.e., holding the curved surface that is convex on the side where the radio waves are incident or reflected. Then, the radio wave reflector 10 in which the radio wave reflector 11 and the holding member 40 are integrated is mounted on the mounting object 24.
  • the radio wave reflecting material 11 is bent so that the convex apex 11c is aligned in the vertical direction and is attached to the outer peripheral surface 40a of the holding member 40.
  • the apex 11c may be aligned in the horizontal direction, or the apex 11c may be attached so that it is aligned in a diagonal direction relative to the vertical or horizontal direction.
  • the radio wave reflecting material 11 may be hemispherical or semi-ellipsoidal, as shown in FIG. 3(C). In FIG. 3(C), the base end of the radio wave reflecting material 11 is attached to the holding member 40.
  • the radio wave reflector 10 may be provided with a rotational position adjustment device 50, which is, for example, a rotating table.
  • the radio wave reflector 10 and the rotational position adjustment device 50 constitute a radio wave reflection device 102.
  • the rotational position adjustment device 50 can rotate the radio wave reflector 10 clockwise and counterclockwise around the vertex 11c when viewed from a cross section along a virtual plane including the incident direction and the reflection direction, that is, in the plan view shown in FIG. 12. As shown in FIG.
  • the radio wave reflector 10 when the radio wave reflector 10 specularly reflects radio waves transmitted from the transmitter 20 toward the receiver 21, the radio wave reflector 10 is at a position where the rotational angle ⁇ is 0 degrees, and the clockwise rotation direction is the + direction and the counterclockwise rotation direction is the - direction.
  • the position of the radio wave reflector 10 that can be adjusted by the rotational position adjustment device 50 may be within a range where the rotational angle ⁇ is -90 degrees or more and +90 degrees or less in the plan view.
  • the receiver 21 can receive radio waves of -95 dB or higher.
  • the radio wave reflector 10 can reflect radio waves with sufficient strength for practical use over a wide range of space, compared to conventional cases where the reflective surface 11d of the radio wave reflector 10 is a flat surface. Therefore, even if the receiver 21 is positioned offset from the specular reflection direction of the radio waves on a virtual plane that includes the incident direction of the incident wave of the radio waves and the reflection direction of the specularly reflected reflected wave, the receiver 21 can receive the radio waves with sufficient strength.
  • the receiver 21 can receive radio waves of sufficient strength for practical use by mounting the radio wave reflector 10 at a position where the rotation angle ⁇ is 0 degrees on a virtual plane including the incident direction of the incident wave and the reflected direction of the reflected wave.
  • the mounting object 24, such as a wall is curved or inclined, the radio wave reflector 10 may deviate from the position where the rotation angle ⁇ is 0 degrees, and the radio wave reflector 10 may be mounted at a position rotated clockwise or counterclockwise from 0 degrees. In such a case, the radio waves are not reflected directly in the direction of the receiver 21, and radio waves of sufficient strength do not reach the receiver 21.
  • the radio wave reflector 10 can reflect radio waves with sufficient strength for practical use over a wide range of space. Therefore, even if the radio wave reflector 10 is attached in a position that is rotated away from the position where it directly reflects the reflected wave toward the receiver 21, the receiver 21 can receive radio waves with a strength that is practical for practical use.
  • the radio wave reflector 10 has a total light transmittance of 65% or more in D65 standard light source (one of the standard light sources defined by the CIE (International Commission on Illumination)), preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more.
  • the total light transmittance refers to the ratio of the total transmitted light flux to the parallel incident light flux of the test piece, and is defined in JIS K7375:2008.
  • the radio wave reflector 10 is so-called "transparent", and "transparent” means that the other side of the radio wave reflector 10 can be seen from one side, including translucency.
  • the radio wave reflector 10 may also be colored as a whole.
  • each layer may be formed of a resin having a total light transmittance of 65% or more, and the conductor 12 of the conductive layer 16 may be formed to a thickness having a total light transmittance of 65% or more.
  • the radio wave reflecting material 11 (sheet-like member) before bending is placed on a plane as shown in FIG. 5 (A)
  • the radio wave reflecting material 11 (sheet-like member) has an overall shape of a square in a plan view, and the length of one side is preferably 20 cm or more and 400 cm or less.
  • Radio waves with frequencies of 2 GHz or more and 300 GHz or less attenuate with distance, but in order to reflect with sufficient strength at all points within a practical distance from the transmitter 20, it is preferable that the length L10 of one side is 20 cm or more.
  • the overall shape is not limited to a square, and may be a rectangle, or a polygon such as a triangle, pentagon, or hexagon, in which case the length of the shortest side is set to 20 cm or more and 400 cm or less.
  • the shortest distance between a certain vertex and the opposite side, or the shortest distance between a certain side and the opposite side may be set to 20 cm or more and 400 cm or less.
  • the overall shape of the radio wave reflecting material 11 is circular, the diameter is set to 20 cm or more and 400 cm or less. If the overall shape of the radio wave reflecting material 11 is elliptical, the minor axis is set to 20 cm or more and 400 cm or less. If the overall shape of the radio wave reflecting material 11 is sector-shaped, the length of the shorter arc or radius is set to 20 cm or more and 400 cm or less.
  • the overall shape may be three-dimensional, such as cylindrical or conical.
  • the receiver 21 In order for the receiver 21 to receive radio waves with sufficient strength for practical use, it is necessary to appropriately set the distance between the transmitter 20 and the radio wave reflecting material 11, and the distance between the receiver 21 and the radio wave reflecting material 11. Furthermore, the longer the wavelength of the radio waves reflected by the radio wave reflecting material 11, i.e., the smaller the frequency of the radio waves, the larger the area of the reflective surface 11d of the radio wave reflecting material 11 must be. For example, if the frequency is less than 6 GHz, and the overall shape of the radio wave reflecting material 11 (sheet-like member) is a square in a plan view, it is preferable to set the length of one side to 200 cm or less.
  • the radio wave reflecting material 11 has a thickness L1 of approximately 0.25 mm, but is not limited to this and it is preferable that the thickness L1 be 1 mm or less. Since the thickness L1 of the radio wave reflecting material 11 is small, the conductor 12 has flexibility. Flexibility refers to the property of having flexibility under normal temperature and pressure, and being able to deform, such as bending, even when a force is applied, without shearing or breaking.
  • the surface resistivity of the radio wave reflecting material 11 when it is attached to a wall or the like and laid flat is preferably 0.003 ⁇ / ⁇ or more and 10 ⁇ / ⁇ or less.
  • the surface resistivity is measured as the surface resistivity of the conductor 12, as will be described in detail later.
  • the surface resistivity of the radio wave reflecting material 11 when laid flat refers to the surface resistivity of the radio wave reflecting material 11 when it is placed on a flat mounting surface.
  • a "flat surface” refers to a surface on which a straight line connecting any two points on the surface is always located.
  • Surface resistivity means the surface resistance per cm2 (1 square centimeter).
  • the surface resistivity can be measured by a four-terminal method in accordance with JIS K6911 by contacting measuring terminals with the surface of the conductive layer 16 described below.
  • the surface resistivity can be measured by an eddy current method using a non-contact resistance meter (manufactured by Napson Corporation, product name: EC-80P, or an equivalent product).
  • the radio wave reflecting material 11 may have plasticity.
  • Plasticity refers to the property of being deformable by the application of external pressure, and of retaining the deformed shape even after the force is removed when pressure causes deformation beyond the elastic limit. All of the synthetic resins constituting the base layer 13, adhesive layer 14, and protective layer 15 may have plasticity, or at least one of the base layer 13, adhesive layer 14, and protective layer 15 may have plasticity.
  • Fig. 4 and Fig. 5 are diagrams showing the radio wave reflecting material 11 (sheet-like member) before bending placed on a flat surface.
  • the radio wave reflecting material 11 may have a conductive layer 16 including a conductor 12, a base layer 13 including a base material for holding the conductive layer 16, a protective layer 15 including a protective material for protecting the conductive layer 16, and an adhesive layer 14 including an adhesive material for bonding the conductive layer 16 and the protective layer 15.
  • the radio wave reflecting material 11 is laminated in the order of the base layer 13, the conductive layer 16, the adhesive layer 14, and the protective layer 15 from the bottom.
  • the up-down direction is defined based on Figure 4, and the length-width direction and left-right direction are defined based on Figures 5 and 6, but the up-down direction, length-width direction and left-right direction are used for the purpose of explanation and do not define the up-down direction and length-width direction when the radio wave reflecting material 11 is used, such as when attached to a building or the like.
  • Figures 1 to 11 do not show the actual scale.
  • the adhesive layer 14 and protective layer 15 are omitted from the illustration of part of the radio wave reflecting material 11.
  • the substrate layer 13 holds the conductor 12 in an aligned state on the upper surface, and is composed of a substrate.
  • the outer shape is formed in a square shape in a plan view, but is not limited thereto, and may be a rectangle, a circle, an ellipse, a sector, a polygon, a three-dimensional shape, etc. according to the overall shape of the radio wave reflecting material 11.
  • a synthetic resin sheet is used as the substrate, which is the substrate layer 13.
  • the synthetic resin examples include one or more selected from the group consisting of PET (polyethylene terephthalate), polyethylene, polypropylene, polyvinyl chloride, polystyrene, polymethyl methacrylate, polyester, polyformaldehyde, polyamide, polyphenylene ether, vinylidene chloride, polyvinyl acetate, polyvinyl acetal, AS resin, ABS resin, acrylic resin, fluororesin, nylon resin, polyacetal resin, polycarbonate resin, polyamide resin, and polyurethane resin.
  • the thickness L2 of the substrate layer 13 (the length in the vertical direction in FIG. 4) is set to 50 ⁇ m, but is not limited thereto.
  • the base material layer 13 may contain any substance such as a synthetic resin or any other material.
  • the conductive layer 16 is preferably formed of one or more linear conductors 12 as a thin film on the upper surface of the base layer 13.
  • the conductors 12 are preferably made of, for example, silver (Ag).
  • the conductors 12 may be made of any metal having free electrons, and are not limited to silver, but may be, for example, gold, copper, platinum, aluminum, titanium, silicon, indium tin oxide, and alloys (for example, alloys containing nickel, chromium, and molybdenum). Examples of alloys containing nickel, chromium, and molybdenum include various grades such as Hastelloy B-2, B-3, C-4, C-2000, C-22, C-276, G-30, N, W, and X.
  • the thickness (film thickness) L3 of the conductive layer 16 is 500 nm (0.5 ⁇ m) in this embodiment, but is not limited to this. From the viewpoint of ensuring appropriate radio wave strength, it is preferable that the thickness L3 is 5 nm or more.
  • the conductive layer 16 may contain, in addition to the conductor 12, any substance such as a synthetic resin or any other material.
  • the conductive layer 16 preferably has a surface resistivity of 3.5 ⁇ / ⁇ or less.
  • the surface resistivity of the conductive layer 16 is the surface resistivity of the radio wave reflecting material 11.
  • the conductive layer 16 is arranged such that one or more linear conductors 12 are arranged surrounding a region 12a where there is no conductor 12. That is, the conductors 12 and the regions 12a where there is no conductor 12 surrounded by the conductors 12 are arranged periodically with a predetermined interval. The interval between adjacent regions 12a where there is no conductor 12 may be equal to the line width L6 of the conductor 12 or may be greater than the line width L6.
  • the linear shape means that the length in the longitudinal direction is 3000 times or more longer than the length in the direction perpendicular to the longitudinal direction. In the arrangement pattern of the conductors 12 in this embodiment, the conductors 12 are arranged at equal intervals along the vertical and horizontal directions, as shown in FIG.
  • the regions 12a where there is no conductor 12 surrounded by the conductors 12 are square. That is, the regions 12a where there is no conductor 12 are arranged with an interval of the line width L6 of the conductor 12.
  • Conductors 12A and 12B are electrically connected at the intersections where conductors 12 (12A) along the horizontal direction and conductors 12 (12B) along the vertical direction overlap.
  • the line width L6 of the conductors 12 is set to 0.1 ⁇ m or more and 4.0 ⁇ m or less.
  • the length L7 between adjacent conductors 12 along the vertical or horizontal direction is set to be greater than the wavelength of visible light and smaller than the wavelength of radio waves reflected by the radio wave reflecting material 11, and in this embodiment, is set to be greater than 2 ⁇ m and less than 10 cm. More preferably, it is greater than 20 ⁇ m and less than 1 cm, and even more preferably, it is greater than 25 ⁇ m and less than 1 mm. Even more preferably, it is greater than 30 ⁇ m and less than 250 ⁇ m.
  • the arrangement pattern of the conductors 12 is not limited to the arrangement shown in FIG. 5(B).
  • the spacing between adjacent horizontally extending conductors 12A may be different from the spacing between adjacent vertically extending conductors 12B, and the shape of the area 12a without conductors 12 may be rectangular.
  • the conductors 12 may also be arranged in the arrangement patterns shown in Figures 6(A) to (E).
  • the conductors 12 are arranged in a brick-laying pattern.
  • a plurality of first linear bodies 12A are arranged horizontally and vertically at a predetermined interval, and a plurality of second linear bodies 12B extending vertically are arranged in a staggered pattern between adjacent first linear bodies 12A in the vertical direction.
  • the staggered pattern refers to a state in which a plurality of second linear bodies 12B extending vertically are arranged horizontally at a predetermined interval, a plurality of second linear bodies 12B forming one row are located between a plurality of second linear bodies 12B forming the row adjacent to this row in the vertical direction, and the second linear bodies 12B of every other row are arranged in a straight line.
  • the area 12a without the conductor 12 is an area surrounded by two adjacent first linear bodies 12A and two adjacent second linear bodies 12B.
  • the conductors 12 are arranged so that the region 12a without the conductors 12 is triangular.
  • the region 12a without the conductors 12 includes a plurality of triangular first regions 12b and a plurality of inverted triangular second regions 12c.
  • the first regions 12b and the second regions 12c are arranged at regular intervals in the horizontal and vertical directions, respectively, and the second regions 12c are arranged between adjacent first regions 12b.
  • Each of the first region 12b and the second region 12c is an area surrounded by the first to third linear bodies 12A to 12C.
  • the first linear body 12A is arranged along the horizontal direction
  • the second linear body 12B is arranged along a direction inclined obliquely with respect to the first linear body 12A
  • the third linear body 12C is arranged along a direction symmetrical to the second linear body 12B with respect to the first linear body 12A.
  • each of the regions 12b and 12c is an equilateral triangle, but it may be an isosceles triangle or a triangle with three sides of different lengths.
  • the conductors 12 are arranged surrounding regular hexagonal regions 12a without conductors 12.
  • the regions 12a without conductors 12 are continuously arranged in the vertical direction at intervals of the line width L6 of the conductors 12, and multiple such rows are arranged in the horizontal direction. Between the regions 12a without conductors 12 adjacent in the vertical direction, the regions 12a without conductors 12 in the adjacent rows in the horizontal direction are arranged.
  • the region 12a without the conductor 12 has a plurality of types of regions 12b to 12d with different shapes.
  • the region 12a without the conductor 12 includes a first region 12b in the shape of a regular pentagon surrounded by linear conductors 12, a second region 12c in the shape of an inverted regular pentagon, and a third region 12d in the shape of a rhombus.
  • the first region 12b to the third region 12d are arranged at regular intervals in the horizontal and vertical directions.
  • first region 12b and the second region 12c are arranged adjacent to each other in the vertical direction with an interval of the line width L6 of the conductor 12, and pairs of the first region 12b and the second region 12c are arranged periodically side by side in the horizontal direction.
  • the third region 12d is arranged between the pair of the first region 12b and the second region 12c adjacent to each other in the horizontal direction.
  • the shapes formed by the first region 12b, the second region 12c, and the third region 12d are arranged at the same period.
  • the region 12a without conductor 12 has a plurality of different shaped regions 12b-12d without conductor 12.
  • the region 12a without conductor 12 has a first region 12b that is circular and surrounded by linear conductors 12, a second region 12c that is substantially triangular, and a third region 12d that is substantially inverted triangular.
  • the first to third regions 12b-12d are periodically arranged at regular intervals in the vertical and horizontal directions.
  • the first regions 12b are periodically arranged side by side in the horizontal and diagonal directions so as to be continuous with an interval of the line width L6 of the conductor 12.
  • Figures 6(A) to (E) only show the conductors 12. Furthermore, the configuration of the conductors 12 other than the arrangement pattern, such as the thickness L3, line width L6, and metal type of the conductors 12, may be set in the same way as in Figure 5(B).
  • the conductive layer 16 preferably has a conductor coverage of 1% or more and 10% or less.
  • the conductor coverage refers to the ratio of the area occupied by the conductor 12 per unit area in a plan view.
  • the coverage can also be said to be the ratio of the area of the base layer 13 covered by the conductor 12 to the area of the base layer 13 in a plan view.
  • the coverage refers to the ratio of the area occupied by the conductor 12 per unit area in a region on the upper surface of the base layer 13 where the conductive layer 16 is provided in a plan view.
  • the region where the conductive layer 16 is provided is the region of the upper surface region of the base layer 13 excluding the peripheral portion of the base layer 13 (the portion between the edge of the base layer 13 and the conductive layer 16).
  • the conductor coverage is measured using a scanning electron microscope (SEM), a transmission electron microscope (TEM), an optical microscope, or the like.
  • the conductive layer 16 having the above arrangement pattern can be manufactured by forming a conductive film, forming a pattern by etching, and extracting a conductive thin film having the pattern.
  • Another method includes coating a photosensitive resist on a base film provided with a lift-off layer, forming a pattern by photolithography, filling the patterned area with a conductor, and then extracting a conductive thin film having the pattern.
  • the conductor 12 constituting the conductive layer 16 may be, for example, in the form shown in Fig. 7.
  • the conductor 12 is formed in a pattern in which a first conductive portion 62 including a plurality of first surrounding portions 61 and a second conductive portion 64 including a plurality of second surrounding portions 63 overlap each other.
  • the first surrounding portion 61 and the second surrounding portion 63 do not have a shared portion with each other.
  • the first conductive portion 62 is formed by repeating the first surrounding portion 61 at a constant pitch, which surrounds the first region AR1 where the conductor 12 is not formed.
  • the first conductive portion 62 is formed in a lattice shape, but it may also be formed in a pentagonal, hexagonal, circular, etc. shape.
  • the second conductive portion 64 surrounds a fourth region AR4 in which no conductor 12 is formed.
  • the fourth region AR4 is formed so as to span multiple adjacent first regions AR1.
  • the second conductive portion 64 may be located on the same plane as the first conductive portion 62, or on a different plane. That is, the second conductive portion 64 may or may not be conductive to the first conductive portion 62. Adjacent second conductive portions 64 may be separated from each other, but may be in contact with each other.
  • the second conductive portion 64 is formed in a quadrangular shape, but may also be formed in a pentagonal, hexagonal, circular, or other shape.
  • the conductor 12 may have, for example, an embodiment as shown in FIG. 8.
  • the embodiment in FIG. 8 differs from the embodiment in FIG. 7 in the shape of the second conductive portion 64 (second surrounding portion 63), and the second surrounding portion 63 is circular.
  • the center point of the second surrounding portion 63 is disposed so as to overlap with an intersection of the first conductive portion 62 formed in a lattice pattern, and the diameter of the second surrounding portion 63 is equal to the lattice pitch of the first conductive portion 62.
  • adjacent second surrounding portions 63 are in contact with each other.
  • adjacent second surrounding portions 63 may be separated from each other.
  • the other configurations are similar to those in the embodiment in FIG. 6, so the same reference numerals are assigned to corresponding configurations and description thereof is omitted.
  • the adhesive layer 14 is for bonding the protective layer 15 onto the base material layer 13 and the conductive layer 16, and is made of an adhesive material.
  • the adhesive layer 14 has a size corresponding to the base material layer 13 in a plan view.
  • a synthetic resin or rubber adhesive sheet is used as the adhesive material of the adhesive layer 14.
  • the synthetic resin include acrylic resin, silicone resin, polyvinyl alcohol resin, etc.
  • the thickness L4 of the adhesive layer 14 is set to 150 ⁇ m, but is not limited to this.
  • the adhesive layer 14 may contain any substance such as a synthetic resin or any member.
  • the adhesive layer 14 is preferably made of a synthetic resin material with a dielectric tangent (tan ⁇ ) of 0.018 or less.
  • the dielectric tangent represents the degree of electrical energy loss within a dielectric, and the greater the dielectric tangent of a material, the greater the electrical energy loss.
  • the synthetic resin material of the adhesive layer 14 has a dielectric constant that changes according to the frequency of the electric field.
  • the dielectric constant is the ratio between the dielectric constant of the medium (the synthetic resin material in this embodiment) and the dielectric constant of a vacuum.
  • the dielectric constant changes between 1.5 or more and 7 or less. More preferably, it is preferable that the dielectric constant changes between 1.8 or more and 6.5 or less.
  • the dielectric loss tangent and the dielectric constant are measured by known methods (e.g., cavity resonator method, coaxial resonator method) using a measuring device (e.g., Toyo Corporation, Model TTPX Tabletop Cryogenic Prober, Material Impedance Analyzer MIA-5M).
  • a measuring device e.g., Toyo Corporation, Model TTPX Tabletop Cryogenic Prober, Material Impedance Analyzer MIA-5M.
  • the synthetic resin material constituting the base layer 13 and protective layer 15 may have a dielectric tangent of 0.018 or less, and may have a relative dielectric constant that changes in response to an electric field.
  • the adhesive layer 14 preferably has a hydroxyl value of 5 mgKOH/g or more, more preferably 8 mgKOH/g or more, even more preferably 30 mgKOH/g or more, and even more preferably 90 mgKOH/g or more.
  • the upper limit of the hydroxyl value of the adhesive layer 14 is preferably 120 mgKOH/g or less. If the hydroxyl value of the adhesive layer 14 is 5 mgKOH/g or more, there is an advantage that the adhesive layer 14 is less likely to foam or/and whiten in a high-temperature and high-humidity environment. In this specification, the hydroxyl value is measured by a test method conforming to JIS K 1557.
  • the acid value of the adhesive layer 14 is preferably 50 mgKOH/g or less, more preferably 45 mgKOH/g or less, even more preferably 30 mgKOH/g or less, and even more preferably 10 mgKOH/g or less.
  • the lower limit of the acid value of the adhesive layer 14 is preferably 0.1 mgKOH/g or more. If the acid value of the adhesive layer 14 is 50 mgKOH/g or less, corrosion of the conductor 12 can be prevented, and the stability of radio wave reflectivity over time can be increased. In this specification, the acid value is measured by a test method conforming to JIS K 2501.
  • the adhesive layer 14 preferably does not contain an ultraviolet absorber. If the adhesive layer 14 does not contain an ultraviolet absorber, this has the advantage that the adhesive layer 14 can be easily adjusted to be colorless and transparent.
  • “not containing” includes not only cases where the adhesive layer 14 does not contain any ultraviolet absorber at all, but also cases where the adhesive layer 14 contains a small amount of ultraviolet absorber that does not impair its colorless transparency.
  • the protective layer 15 has a size corresponding to the base layer 13 in a plan view, protects the conductor 12, and is composed of a protective material.
  • a synthetic resin film is used as the protective material of the protective layer 15.
  • the synthetic resin include one or more selected from the group consisting of PET (polyethylene terephthalate), COP (cycloolefin polymer), polyethylene, polypropylene, polyvinyl chloride, polystyrene, polymethyl methacrylate, polyester, polyformaldehyde, polyamide, polyphenylene ether, vinylidene chloride, polyvinyl acetate, polyvinyl acetal, AS resin, ABS resin, acrylic resin, fluorine resin, nylon resin, polyacetal resin, polycarbonate resin, polyamide resin, and polyurethane resin.
  • the thickness L5 of the protective layer 15 is set to 50 ⁇ m, but is not limited thereto.
  • the protective layer 15 may contain any synthetic resin or other substance or
  • the protective layer 15 may be, for example, a synthetic resin film, and at least one of the upper surface (outer surface) and the lower surface (surface in contact with the adhesive layer 14) in FIG. 4 may be treated with an anti-glare or anti-reflection treatment.
  • Anti-glare treatment refers to a treatment in which an uneven shape is formed on at least one surface of the protective layer 15, scattering light and suppressing reflection of light sources such as lighting on the protective layer 15.
  • One method for carrying out anti-glare treatment is, for example, to apply a binder resin with fine particles dispersed therein to the surface of the film. Other known methods such as sandblasting and chemical etching may also be used.
  • Anti-reflection treatment is a process in which an anti-reflection coating is formed on at least one surface of the film, and the light reflected from the surface of the anti-reflection coating and the light reflected from the interface between the anti-reflection coating and the film are attenuated through interference, suppressing the reflection of light sources such as lighting.
  • the anti-reflection coating may be a single layer, or may be a laminate of thin films with different refractive indices, and any known anti-reflection coating may be used.
  • the protective layer 15 may be a synthetic resin film with an anti-glare or anti-reflection treated film attached to one or both sides.
  • the moisture permeability of the protective layer 15 at a temperature of 40° C. and a humidity of 90% rh (relative humidity) is preferably 20 g/m 2 ⁇ 24 h or less, more preferably 16 g/m 2 ⁇ 24 h or less, even more preferably 12 g/m 2 ⁇ 24 h or less, and even more preferably 10 g/m 2 ⁇ 24 h or less.
  • the moisture permeability of the protective layer 15 at a temperature of 40° C. and a humidity of 90% rh (relative humidity) is 20 g/m 2 ⁇ 24 h or less, there is an advantage that the conductive layer 16 is less likely to corrode and the surface resistivity of the conductive layer 16 is less likely to increase.
  • the “moisture permeability” in this specification is measured by a test method in accordance with JIS Z 0208 (1976).
  • FIG. 9 is a diagram showing a state in which the radio wave reflecting material 11 (sheet-like member) before bending is placed on a plane.
  • the radio wave reflecting material 11 shown in FIG. 9 has two conductive layers 16A and 16B laminated in the up-down direction.
  • the conductive layer 16A formed on the base layer 13A and the conductive layer 16B formed on the base layer 13B are aligned so that their arrangement patterns overlap when viewed from a plane.
  • the arrangement patterns of the conductive layers 16A and 16B do not have to overlap when viewed from a plane, and the conductive layers 16A and 16B may be formed in different arrangement patterns.
  • the lower surface of the base layer 13B is attached to the conductive layer 16A by an adhesive layer 14A, and the protective layer 15 is attached to the conductive layer 16B by an adhesive layer 14B.
  • the radio waves incident on the radio wave reflecting material 11 are reflected by the first conductive layer 16B, but some of the radio waves pass through the conductive layer 16B without being reflected by the conductive layer 16B.
  • the radio waves that pass through the conductive layer 16B are reflected by the second conductive layer 16A.
  • the radio waves that pass through the upper conductive layer 16B can be reflected by the lower conductive layer 16A, and the reflection intensity of the radio wave reflecting material 11 can be kept higher than when there is only one layer of conductor 12.
  • two adhesive layers 14A and 14B are used, the value of the dielectric tangent is even smaller than that of the embodiment shown in FIG. 4, and the reflection intensity can be kept even higher.
  • the other configurations and functions are the same as those of the embodiment shown in FIG. 4 and FIG. 5, and detailed explanations are omitted by assigning the same reference numerals to corresponding configurations.
  • the conductive layer 16 formed on the base layer 13 is laminated in two layers, but it may be laminated in three or more layers. As the number of laminated conductive layers 16 increases, the reflection intensity increases, but the overall thickness of the radio wave reflecting material 11 increases, resulting in a decrease in total light transmittance and flexibility. For this reason, the number of laminated conductive layers 16 is appropriately set according to the intended use, etc.
  • FIG. 10 shows another embodiment of the radio wave reflecting material 11.
  • FIG. 10 is a diagram showing the state in which the radio wave reflecting material 11 (sheet-like member) before bending is placed on a plane.
  • the radio wave reflecting material 11 includes a conductive layer 16 and a base layer 13, and does not include an adhesive layer 14 and a protective layer 15.
  • the conductor 12 of the conductive layer 16 is formed in a square shape as a sheet-like thin film on substantially the entire upper surface of the base layer 13.
  • the thickness L3 of the conductor 12 is 10 nm in this embodiment, but is not limited to this.
  • the surface resistivity is 9.8 ⁇ / ⁇ in this embodiment.
  • FIG. 10 is a diagram showing the state in which the radio wave reflecting material 11 (sheet-like member) before bending is placed on a plane.
  • the radio wave reflecting material 11 includes a conductive layer 16 and a base layer 13, and does not include an adhesive layer 14 and a protective layer 15.
  • the conductor 12 of the conductive layer 16 is formed in a
  • the conductor coverage is defined as the ratio of the area occupied by the conductor 12 per unit area in the part where the conductive layer 16 on the base layer 13 is provided, and the conductor coverage is 100%.
  • the total light transmittance of the radio wave reflecting material 11 is 70%.
  • the conductive layer 16 is composed of one conductor 12, but it may be composed of multiple conductors 12. In this case, multiple conductors 12 are arranged at predetermined intervals over substantially the entire upper surface of the base layer 13.
  • the shape of the conductor 12 may be circular, rectangular, triangular, polygonal, etc.
  • the radio wave reflector 10 including any one of the radio wave reflecting materials 11 described above may be used by being included in a building material 30.
  • the building material 30 can be attached to a building as, for example, a wall surface, ceiling surface, floor surface, wallpaper for a partition, a decorative material 30A such as a poster, and a decorative material 30B such as a transparent sticker for a light cover, as shown in Fig. 11 (A) for example.
  • a decorative materials 30A and 30B including the radio wave reflector 10 to a wall surface 31 and a light cover 32, radio waves that enter the room from the outside through a window 33 or the like are reflected by the decorative materials 30A and 30B provided on the wall surface 31 and the light cover 32. This allows radio waves to reach a wider range of the indoor space S, improving the convenience of radio wave reception.
  • the radio wave reflector 10 may be formed as something held inside the building material 30.
  • the wall surface 31 itself or the light cover 32 itself, which is the building material 30, may be composed of the radio wave reflector 10.
  • the building material 30 is not limited to the wall or light cover inside the room, but may be a partition, a pillar, a lintel, the exterior wall of a building, a window, etc.
  • FIG. 11(B) is a plan view of the room, and the building material 30, which is the radio wave reflector 10, is formed as a corner pillar 30C having a curved surface at the corner of the room. Radio waves entering from the window 33 are reflected by the corner pillar 30C, and the radio waves reach a wider range of the indoor space S.
  • FIGS. 11(A) and 11(B) show examples of application of the building material 30, and do not show the actual range of reflection of radio waves.
  • the radio wave reflector 10 is not limited to the building material 30, and may be held inside a member made of a non-conductive material such as resin and used in any location.
  • Examples 1 to 10 and Comparative Examples 1 and 2 were produced as the radio wave reflector 10, and evaluation tests were performed on the reception strength of the receiver 21 for Examples 1 to 10 and Comparative Examples 1 and 2.
  • the radio wave reflector 10 of the present invention is not limited to Examples 1 to 10.
  • the radio wave reflector 10 of Examples 1 to 4 is a sheet-like member having a square planar shape, a side length L10 of 40 cm, and a thickness L1 of 0.25 mm before being attached to the attachment object 24.
  • This sheet-like member is bent so that the top and bottom side edges 11b of the radio wave reflecting material 11 (sheet-like member) approach each other, so that the apex 11c of the convex shape is located in the center in the left-right direction, to form the shape shown in Fig. 2(A) and Fig. 2(B). That is, as shown in Fig. 2(A), the radio wave reflector 10 has a semicircular cross section along an imaginary plane including the incident direction and the reflection direction, and has a shape that is convex on the side where the radio wave is incident or reflected.
  • Example 1 Bottom width L11 (cm): 39.8 Curvature 1/r (1/m): 0.87
  • Example 2 Bottom width L11 (cm): 35.0 Curvature 1/r (1/m): 2.21
  • Example 3 Bottom width L11 (cm): 30.0 Curvature 1/r (1/m): 3.19
  • Example 4 Bottom width L11 (cm): 20.0 Curvature 1/r (1/m): 4.73
  • Comparative example 1 is a sheet-like member with a square planar shape, a side length L10 of 40 cm, and a thickness L1 of 0.25 mm, and does not have a convex reflective surface 11d, in which the reflective surface 11d is a flat surface.
  • it is the sheet-like member shown in FIG. 5(A), and can be said to be the radio wave reflector 10 before being bent.
  • Examples 1 to 4 and Comparative Example 1 are as follows. Note that, unless otherwise specified, Examples 1 to 4 and Comparative Example 1 have the same configuration, so in the following explanation, only Example 1 will be explained, and an explanation of Examples 2 to 4 and Comparative Example 1 will be omitted.
  • the radio wave reflecting material 11, which is the radio wave reflector 10 produced as Example 1, has a conductive layer 16, a base layer 13, a protective layer 15, and an adhesive layer 14 containing an adhesive for adhering the conductive layer 16 and the protective layer 15, and is laminated in the order of the base layer 13, the conductive layer 16, the adhesive layer 14, and the protective layer 15 from the bottom.
  • the thickness L1 of the radio wave reflecting material 11 is the sum of the thickness L3 of the conductive layer 16, the thickness L2 of the base layer 13, the thickness L4 of the adhesive layer 14, and the thickness L5 of the protective layer 15.
  • the thickness L3 of the conductive layer 16 is much thinner than the thicknesses L2, L4, and L5 of the base layer 13, the adhesive layer 14, and the protective layer 15, the thickness L1 of the radio wave reflecting material 11 does not take into account the thickness L3 of the conductive layer 16.
  • a synthetic resin material sheet made of PET (Lumirror 50T60, manufactured by Toray Industries, Inc.) was used as the base layer 13, and the thickness L2 of the base layer 13 was set to 50 ⁇ m.
  • the conductors 12 of the conductive layer 16 are linear thin metal films made of silver (Ag), with a thickness (film thickness) L3 of 500 nm, a line width L6 of 0.5 ⁇ m, and a length L7 between adjacent conductors 12 of 60 ⁇ m.
  • the surface resistivity of the conductive layer 16 is 1.7 ⁇ / ⁇ , and the conductor coverage is 3.3%.
  • a rubber-based adhesive was used as the adhesive layer 14.
  • the adhesive layer 14 was prepared by adding 100 parts by weight of a rubber-based polymer (a mixture of 50% by weight of styrene-(ethylene-propylene)-styrene type block copolymer and 50% by weight of styrene-(ethylene-propylene) type block copolymer, 15% styrene content, and 130,000 weight average molecular weight), 40 parts by weight of a synthetic resin (FMR-0150, manufactured by Mitsui Chemicals), 20 parts by weight of a softener (LV-100, manufactured by JX Nippon Oil & Energy Corporation), 0.5 parts by weight of an antioxidant (ADEKA Corporation, Adekastab AO-330), and 150 parts by weight of toluene to a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer, a dropping funnel, and a stirring device, and stirring the mixture at 40°C for 5 hours.
  • a synthetic resin sheet made of PET (Lumirror 50T60, manufactured by Toray Industries, Inc.) was used as the protective layer 15.
  • the thickness L5 of the protective layer 15 was set to 50 ⁇ m.
  • the thickness L1 of the radio wave reflecting material 11, the thickness L3 of the conductive layer 16, the thickness L2 of the base layer 13, the thickness L4 of the adhesive layer 14, and the thickness L5 of the protective layer 15 are determined by measuring multiple arbitrary locations and calculating the average of the obtained measured values.
  • a reflectance spectroscopic film thickness measuring instrument e.g., F3-CS-NIR, manufactured by Filmetrics Inc.
  • F3-CS-NIR a reflectance spectroscopic film thickness measuring instrument
  • the conductor 12 is formed on the base layer 13.
  • a 0.01 to 3 ⁇ m core layer is formed on one surface of a 5 to 200 ⁇ m thick copper foil that has sufficient strength as a metal layer by a method such as electrolytic or electroless plating.
  • a conductive layer 16 is formed in a predetermined arrangement pattern on the surface of the core layer by a method such as electrolytic or electroless plating.
  • the entire conductive layer 16 is covered with the base layer 13.
  • An adhesive is applied to the base layer 13 in advance.
  • the copper foil and core layer are then etched away. This forms the conductor 12 on the base layer 13.
  • the protective layer 15 is attached to the conductor 12 on the side opposite the base layer 13 using the adhesive layer 14.
  • the protective layer 15 is attached to the conductor 12 on the base layer 13 using the adhesive layer 14, taking care not to trap air bubbles. In this way, the radio wave reflecting material 11 is manufactured.
  • the surface resistivity was measured in accordance with JIS K6911 by contacting measuring terminals with the surface of the conductive layer 16 when the conductive layer 16 was formed and exposed during the manufacture of Example 1 and Comparative Examples 1 and 2.
  • the radio wave reflecting system 100 used in the evaluation test A will be described.
  • the radio wave reflecting system 100 includes a transmitter 20, a receiver 21, and a rotational position adjustment device 50.
  • a support plate 51 is attached to the rotational position adjustment device 50 (also referred to as the "rotation table 50"), and the radio wave reflectors 10 of Examples 1 to 4 and Comparative Example 1 (hereinafter also referred to as the “samples") are attached to this support table 51.
  • the side edge 11b of the radio wave reflector 10 is fixed to the support plate 51 so that the apex 11c of the radio wave reflector 10 is located at the center of rotation of the rotation table 50 in a plan view.
  • the transmitter 20 and the receiver 21 are fixed at a position corresponding to the center position of the vertical length of the radio wave reflector 10.
  • the transmitter 20, the receiver 21, and the apex 11c located at the center of the vertical direction of the radio wave reflector 10 are arranged on the same plane.
  • This plane is a surface that includes the incident direction and reflection direction of the radio wave.
  • the specular reflection angle is set to 60 degrees
  • the distance between the apex 11c of the radio wave reflector 10 and the transmitter 20 is set to 4 m
  • the distance between the apex 11c of the radio wave reflector 10 and the receiver 21 is set to 6 m.
  • a rectangular horn antenna was used as the receiver 21 (receiving antenna), and a spectrum analyzer (Anritsu MS2760A) was connected to the receiver 21. An amplifier was placed between the receiver 21 and the spectrum analyzer. Radio waves with a frequency of 60 GHz were output from the transmitter 20, and the reception strength by the receiver 21 was measured.
  • the receiving antenna is not limited to a rectangular horn antenna, and other directional antennas such as a dipole antenna or non-directional antennas such as an omni antenna may also be used.
  • the method for measuring the reception strength (received power) of the sample by the receiver 21 is as follows.
  • the radio wave reflector 10 is rotated around the vertex 11c of the radio wave reflector 10.
  • the position of the radio wave reflector 10 when the radio wave is specularly reflected is defined as a rotation angle ⁇ of 0 degrees, and the radio wave reflector 10 is rotated by 1 degree in the range from -90 degrees to +90 degrees, and the reception strength of the receiver 21 is measured at each rotation angle ⁇ position.
  • the + direction is the clockwise direction in FIG. 12, and the - direction is the counterclockwise direction in FIG. 12.
  • the radio wave transmitted to the sample has a frequency of 60 GHz and an output of 1 mW from the transmitter 20.
  • evaluation index As an evaluation index, the reception strength (received power) received by the receiver 21 at each rotation angle ⁇ of the radio wave reflector 10 was measured, and the range of rotation angle ⁇ of the radio wave reflector 10 where the receiver 21 can receive radio waves at a strength of -95 dB or more, which is a practical strength for use, was determined.
  • Figure 13 shows the results of Comparative Example 1, in which the receiver 21 receives radio waves with an intensity of -95 dB or more when the rotation angle ⁇ of the radio wave reflector 10 is in the range from approximately -15 degrees to approximately +15 degrees.
  • Figure 14 shows the results of Example 1, where the receiver 21 receives radio waves at an intensity of -95 dB or more when the rotation angle ⁇ of the radio wave reflector 10 is in the range of approximately -25 degrees to approximately +15 degrees.
  • Figure 15 shows the results of Example 2, where the receiver 21 receives radio waves at an intensity of -95 dB or more when the rotation angle ⁇ of the radio wave reflector 10 is in the range of approximately -50 degrees to approximately +35 degrees.
  • Figure 16 shows the results of Example 3, where the receiver 21 receives radio waves at an intensity of -95 dB or more when the rotation angle ⁇ of the radio wave reflector 10 is in the range of approximately -45 degrees to approximately +60 degrees.
  • Figure 17 shows the results of Example 4, where the receiver 21 receives radio waves at an intensity of -95 dB or more when the rotation angle ⁇ of the radio wave reflector 10 is in the range of approximately -83 degrees to approximately +83 degrees.
  • the radio wave reflector 10 with a convex shape of Examples 1 to 4 had a larger range of rotation angle ⁇ at which the receiver 21 could receive radio waves with sufficient strength for practical use. Therefore, even if the radio wave reflector 10 was attached at a position rotated within a predetermined range of rotation angle ⁇ around the apex 11c, the receiver 21 was able to receive radio waves with sufficient strength for practical use. Furthermore, in Examples 1 to 4, the smaller the bottom width L11, i.e., the greater the curvature, the larger the range of rotation angle ⁇ at which the receiver 21 can receive radio waves with sufficient strength for practical use.
  • the radio wave reflector 10 can reflect radio waves with sufficient strength for practical use over a wide range of space, compared to when the reflective surface 11d of the radio wave reflector 10 is flat. Therefore, even if the radio wave reflector 10 is attached at a position rotated within a predetermined range of rotation angle ⁇ around the apex 11c, the receiver 21 can receive radio waves with sufficient strength for practical use.
  • Evaluation Test B (Examples 5 to 10)
  • Examples 5 to 10 used in evaluation test B are sheet-like members having a rectangular planar shape, vertical and horizontal dimensions of 539 mm ⁇ 485 mm, and a thickness L1 of 0.16 mm before being attached to the attachment target 24.
  • the values of the width L11 of the bottom and the curvature 1/r are shown below.
  • Example 5 Bottom width L11 (mm): 482 Curvature 1/r (1/m): 0.792 (6)
  • Example 6 Bottom width L11 (mm): 462 Curvature 1/r (1/m): 2.23 (7)
  • Example 7 Bottom width L11 (mm): 438 Curvature 1/r (1/m): 3.24 (8)
  • Example 8 Bottom width L11 (mm): 385 Curvature 1/r (1/m): 4.75 (9)
  • Example 9 Bottom width L11 (mm): 365 Curvature 1/r (1/m): 5.25 (10)
  • Example 10 Bottom width L11 (mm): 243 Curvature 1/r (1/m): 7.81
  • the conductors 12 of the conductive layer 16 are linear thin metal films made of copper (Cu), with a thickness (film thickness) L3 of 1.6 ⁇ m, a line width L6 of 2.4 ⁇ m, and a length L7 between adjacent conductors 12 of 100 ⁇ m.
  • the surface resistivity of the conductive layer 16 is 0.7 ⁇ / ⁇ , and the conductor coverage is 7%.
  • the rest of the configuration is the same as in Example 1, so a description is omitted.
  • Comparative example 2 is a sheet-like member with a rectangular planar shape and vertical and horizontal dimensions of 539 mm x 485 mm. The rest of the configuration is the same as comparative example 1, so a description is omitted.
  • the radio wave reflection system 110 used in the evaluation test B will be described. As shown in FIG. 18, the radio wave reflection system 110 includes a transmitter 20, a receiver 21, and a moving mechanism (not shown) for the receiver 21.
  • the frequency of the radio wave transmitted by the transmitter 20 is 2 GHz or more and 300 GHz or less.
  • the radio wave reflector 10 is fixed so as to be convex on the sides of the direction of incidence and the direction of reflection of the radio wave, and does not rotate.
  • the transmitter 20 and the receiver 21 are disposed at a position corresponding to the center position of the vertical length of the radio wave reflector 10.
  • the transmitter 20, the receiver 21, and the apex 11c located at the center of the vertical direction of the radio wave reflector 10 are disposed on the same plane.
  • This plane is a surface that includes the direction of incidence and the direction of reflection of the radio wave.
  • the transmitter 20 is disposed on the normal 22 at the apex 11c of the radio wave reflector 10.
  • the distance between the apex 11c and the transmitter 20 is set to 1.0 m.
  • the receiver 21 can be moved by a moving mechanism along a virtual circumference centered on the vertex 11c and having a radius equal to the distance between the vertex 11c and the transmitter 20.
  • the other configurations of the radio wave reflecting system 110 are the same as those of the radio wave reflecting system 100 used in the evaluation test A.
  • the method of measuring the reception strength (reception power) of the sample by the receiver 21 is as follows. In plan view, the position of the receiver 20 is changed. When the receiver 21 is located on the normal 22 of the vertex 11c of the radio wave reflector 10 on the above-mentioned plane, the rotation angle ⁇ 2 of the receiver 21 is set to 0 degrees, and the receiver 21 is rotated in increments of 15 degrees in the range from -75 degrees to +75 degrees, and the reception strength of the receiver 21 is measured at each rotation angle ⁇ 2 position. Note that the + direction is the counterclockwise direction in FIG. 18, and the - direction is the clockwise direction in FIG. 18. The output of the radio wave transmitted to the sample from the transmitter 20 is 1 mW.
  • the rotation angle ⁇ 2 of the receiver 21 was changed as described above to measure the reception strength (received power) received by the receiver 21 for Examples 5 to 10 and Comparative Example 2.
  • the frequencies of the radio waves transmitted to the samples were 4.85 GHz and 28 GHz.
  • the evaluation was performed as follows. The absolute value of the difference between the reflection intensity in the case of regular reflection (i.e., rotation angle ⁇ 2 is 0 degrees) and the reflection intensity for other rotation angles ⁇ 2 is found, and a rotation angle ⁇ 2 for which the absolute value of the difference does not exceed 10 dB is extracted.
  • the extracted rotation angle ⁇ 2 has a value ranging from + to -.
  • the absolute values of the maximum and minimum values of the extracted rotation angles ⁇ 2 are found, and the smaller absolute value is selected.
  • the absolute value with a + sign and the absolute value with a - sign are found, and the difference between these values is set as the angle range (unit: degrees) of rotation angle ⁇ 2 for which receiver 21 can receive radio waves with sufficient reception strength.
  • Example 5 in the case of Example 5 shown in Table 1, -30 degrees, -15 degrees, +15 degrees, +30 degrees, and +45 degrees were extracted as rotation angles for which the absolute value of the difference between the reflection intensity when the rotation angle ⁇ 2 is 0 degrees and the reflection intensity for other rotation angles ⁇ 2 does not exceed 10 dB.
  • the maximum value of the extracted rotation angle ⁇ 2 was 45, the minimum value was -30, and the absolute values were 45 and 30, respectively, so the smaller of these, 30, was selected.
  • the absolute value with a + sign attached is +30, and the absolute value with a minus sign attached is -30, and the difference between these two, 60, was set as the angle range (unit: degrees) of the rotation angle ⁇ 2 for which the receiver 21 can receive radio waves with sufficient reception strength.
  • An angle range of 150 degrees or more was rated as “ ⁇ "
  • an angle range of 120 degrees or more but less than 150 degrees was rated as “ ⁇ ”
  • an angle range of 60 degrees or more but less than 120 degrees was rated as “ ⁇ ”
  • an angle range of less than 60 degrees was rated as “ ⁇ ”. If rated as " ⁇ ", “ ⁇ ”, or “ ⁇ ”, the radio wave reflector 10 can reflect radio waves over a sufficiently wide angle range with sufficient strength for practical use.
  • Tables 1 and 2 show the measurement results of the reception strength and the evaluation of the angle range for the rotation angle ⁇ 2 of the receiver 21.
  • Figures 19 and 20 are tables showing the measurement results of the reception strength.
  • the range colored in gray indicates the angle range of the rotation angle ⁇ 2 in which the receiver 21 can receive radio waves with sufficient reception strength.
  • Figure 19 and Table 1 show the results when the frequency of the radio waves is 4.85 GHz
  • Figure 20 and Table 2 show the results when the frequency of the radio waves is 28 GHz.
  • the angle range in which the receiver 21 can receive radio waves with sufficient reception strength is wider than in the case of regular reflection, compared to the flat radio wave reflector 10 of Comparative Example 2.
  • the radio wave reflector 10 was able to reflect radio waves with a strength sufficient for practical use.
  • the angle range in which the receiver 21 can receive radio waves with sufficient reception strength increases.
  • expressions expressing that things are in an equal state such as “same,” “equal,” and “homogeneous,” not only express a strictly equal state, but also express a state in which there is a tolerance or a difference to the extent that the same function is obtained.
  • expressions expressing shapes such as a square shape or a cylindrical shape not only express shapes such as a square shape or a cylindrical shape in the strict geometric sense, but also express shapes including uneven parts and chamfered parts to the extent that the same effect is obtained.
  • the expressions "comprise,” “include,” “have,” “include,” or “have” of one component are not exclusive expressions that exclude the presence of other components.
  • Radio wave reflector 11 Radio wave reflecting material 11b Side edge 11c Convex apex 12 Conductor 13 Base material layer 14 Adhesive layer 15 Protective layer 16 Conductive layer 20 Transmitter 21 Receiver 24 Mounting object 40 Holding member 50 Rotational position adjustment device (rotating table) 100 Radio wave reflecting system 101 Radio wave reflecting structure 102 Radio wave reflecting device L6 Line width of conductor L10 Length of one side of radio wave reflector L11 Width of bottom of radio wave reflector ⁇ , ⁇ 2 Rotation angle

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PCT/JP2023/040834 2022-11-14 2023-11-13 電波反射体、電波反射体の作製方法、電波反射構造体、電波反射システムおよび電波反射装置 Ceased WO2024106405A1 (ja)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2025206225A1 (ja) * 2024-03-27 2025-10-02 旭化成株式会社 三次元曲面を持つ構造体

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01204506A (ja) * 1988-02-10 1989-08-17 Japan Synthetic Rubber Co Ltd 積層体及びそれを用いたアンテナ用部品
JPH025991U (https=) * 1988-06-27 1990-01-16
JP2004320681A (ja) * 2003-04-21 2004-11-11 Nec Corp 電波反射板の構造
JP2017175342A (ja) * 2016-03-23 2017-09-28 Kddi株式会社 電波反射装置、通信システム及び設定方法
WO2022163813A1 (ja) * 2021-01-29 2022-08-04 積水化学工業株式会社 構造体、及び建築材料

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01204506A (ja) * 1988-02-10 1989-08-17 Japan Synthetic Rubber Co Ltd 積層体及びそれを用いたアンテナ用部品
JPH025991U (https=) * 1988-06-27 1990-01-16
JP2004320681A (ja) * 2003-04-21 2004-11-11 Nec Corp 電波反射板の構造
JP2017175342A (ja) * 2016-03-23 2017-09-28 Kddi株式会社 電波反射装置、通信システム及び設定方法
WO2022163813A1 (ja) * 2021-01-29 2022-08-04 積水化学工業株式会社 構造体、及び建築材料

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2025206225A1 (ja) * 2024-03-27 2025-10-02 旭化成株式会社 三次元曲面を持つ構造体

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