JP2008270793A - Electromagnetic wave absorber, building material, and electromagnetic absorption method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic wave absorber having multi-modal or wide-band properties, capable of improving the absorbed amount of electromagnetic waves, and to provide an architectural material and an electromagnetic absorption method. <P>SOLUTION: The electromagnetic wave absorber is constituted of a lamination of a pattern layer 5 and a loss layer. The pattern layer 5 has patterns 12, formed thereon which are made of conductive material, such as metals. The patterns 12 include small square pieces 13, large square pieces 14, and rectangular pieces 15a, 15b and has a translation symmetry. The rectangular pieces 15a and 15b have an interior angle of 180° or smaller and are formed into polygonal shapes or ellipses, excluding regular polygons, and are disposed so as to be directed in different directions. By having such a pattern layer 5, it is possible to obtain superior an electromagnetic absorber 1, having at least one of the multi-modal and wide-band property, with a large absorption volume. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electromagnetic wave absorber and a building material that capture and absorb electromagnetic waves, and an electromagnetic wave absorption method.

A communication system that constructs a wireless local area network (LAN) using microwaves and wirelessly communicates between computers as communication terminal devices is used. A communication system in which a communication terminal device is connected to a wide area network called FWA (Fixed Wireless Access) so as to perform wireless communication is used. Furthermore, a communication system that constructs a WPAN (Wireless Personal Area Network) that performs wireless communication according to Bluetooth, which is a short-range wireless communication standard, and performs wireless communication between communication terminal devices is used. Furthermore, VoWLAN (Voice
There has been proposed a communication system using a cellular phone device that constructs a wireless LAN called an “over Wireless Local Area Network” and performs a voice call. As one of communication systems, an RFID (Radio Frequency Identification) system using UHF electromagnetic waves has been put into practical use. Although the UHF band has not been standardized internationally, an RFID system that uses UHF electromagnetic waves can achieve a communication distance of 10 meters and is being used in a wide range of applications such as product management, logistics management, and product traceability. ing.

  When such a communication system for wireless communication is constructed close to each other, or when an apparatus using electromagnetic waves such as a microwave oven and an antitheft device by wireless communication is used in an environment where the communication system is constructed, it is called other wave interference. May cause electromagnetic interference. In addition to this, there is a risk of erroneous transmission due to reflected waves called multipath, self-interference, and the like. As a result, the transmission speed between communication terminal devices decreases, the BER (Bit Error Rate) increases, that is, the communication environment deteriorates, and information transmission causes errors. In addition, there is concern about the influence on electronic devices provided around the communication system, and in the worst case, the electronic devices may malfunction.

  In order to solve these problems, an electromagnetic wave absorber including a pattern layer having a conductive pattern body is used. The electromagnetic wave absorber captures an electromagnetic wave by causing the conductive pattern body to function as a receiving antenna, and attenuates the captured electromagnetic wave by the conductive pattern body and the loss layer. The absorber is configured to efficiently capture the electromagnetic wave by reducing the reflection by causing interference between the electromagnetic wave reflected from the surface and the electromagnetic wave that has once passed through the absorber and re-radiated.

As an electromagnetic wave absorber, for example, there is a radio wave reflection preventing body disclosed in Patent Document 1. The radio wave antireflection body of Patent Document 1 includes a metal radio wave reflector layer, a resin layer containing at least one powder selected from ferrite and carbon having a particle diameter of 100 μm or less, and a plurality of geometric patterns. A structure formed by sequentially laminating pattern coating layers having a volume resistivity of 10 ⁻³ to 10 ⁵ Ω · cm and a film thickness of 5 to 500 μm, which are arranged so as not to contact each other and contain metal powder. Have. The ratio of the non-coating part / coating part in the pattern of the pattern coating layer is 0.05 to 20, and the pattern coating is a checkered pattern, a polygon or a circle.

Moreover, as an electromagnetic wave absorber, there exists an electromagnetic wave reflection prevention body shown by patent document 2, for example. The radio wave prevention body of Patent Document 2 is a pattern resin that is formed in a geometric pattern and has a volume specific resistance value of 10 ³ Ω · cm or less, a support layer, and 25 to 70% by volume of voids. It is the structure provided with the laminated body formed by laminating | stacking a layer and a support layer one by one.

Japanese Patent No. 3209456 (JP-A-6-140787) JP-A-6-252582

  In the radio wave antireflection body shown in Patent Document 1, the pattern coating film layer is formed so that the ratio of the non-coating part / coating part in the pattern is 0.05 to 20, and the radio wave shown in Patent Document 2 In the antireflection body, the pattern resin layer is formed so that 25 to 70% by volume is a gap. As described above, the radio wave antireflection body disclosed in Patent Documents 1 and 2 is configured in consideration of what ratio the pattern should be formed, but it is desired to further improve the amount of electromagnetic wave absorption. . In addition, an electromagnetic wave absorber that can absorb electromagnetic waves with a plurality of frequencies or electromagnetic waves with a wide frequency range is desired.

  An object of the present invention is to provide an electromagnetic wave absorber, a building material, and an electromagnetic wave absorption method that have multimodality or broadband properties and can improve the amount of electromagnetic wave absorption.

  The present invention relates to a pattern layer in which a conductive pattern body made of a conductive material is formed, the conductive pattern bodies being provided apart from each other, each interior angle being 180 ° or less, and a regular polygon shape A pattern layer having a translational symmetry, including a pattern piece formed in a polygonal shape or an ellipse excluding, and arranged in different directions;

  An electromagnetic wave absorber comprising a loss layer having a portion made of a material that is at least one of a magnetic loss material and a dielectric loss material.

  Further, the invention is characterized in that the pattern pieces are arranged so as to have a rotational symmetry of three times or more.

  Further, the invention is characterized in that the pattern pieces are arranged so as to have at least one of rotational symmetry of 3, 4, or 6 times.

  In the invention, it is preferable that the pattern layer has an area ratio in which the area of the region where the conductive pattern body is formed is 0.55 or more when the area of the entire pattern layer region is 1. .

  Further, the invention is characterized in that the pattern pieces and the pattern pieces formed into regular polygons or circles are arranged in combination.

Further, in the present invention, the pattern piece is formed in a rectangle whose length dimension of each side is not less than the first dimension and not more than the second dimension,
The conductive pattern body further includes a small square pattern piece whose one side length is a first dimension, and a large square pattern piece whose one side length is a second dimension larger than the first dimension. It is an electromagnetic wave absorber characterized by this.

  In the invention, it is preferable that the rectangular pattern piece is a rectangle including two short sides having a first dimension and two long sides having a second dimension.

  In the present invention, the small square pattern piece and the large square pattern piece are arranged by arranging a diagonal line of the small square pattern piece and a diagonal line of the large square pattern piece on the same straight line. Two rectangular pattern pieces are arranged such that the short side faces one side of the small square pattern piece and the long side faces one side of the large square pattern piece, and the four pattern pieces Are arranged in a pattern group.

  Further, the present invention is characterized in that at least one corner portion of the corner portion of the small square pattern piece and the corner portion of the large square pattern piece is formed in a curved shape.

  The present invention is characterized in that at least one corner of the rectangular pattern pieces is formed in a curved shape.

  In the invention, it is preferable that the pattern layer has an area ratio in which the area of the region where the conductive pattern body is formed is 0.6 or more when the area of the entire pattern layer region is 1.

  According to the present invention, the loss layer has at least a layer made of a magnetic loss material.

In the present invention, the loss layer is
A layer of at least a magnetic loss material;
And a layer made of at least a dielectric loss material.

Further, the present invention is characterized in that it absorbs electromagnetic waves of two or more arbitrarily different frequencies.
In the present invention, the pattern layer includes a plurality of pattern pieces, and the fundamental resonance frequency and the higher order resonance frequency of one pattern piece are different from the fundamental resonance frequency of at least one pattern piece of the other pattern pieces. It is characterized by that.

  In addition, the present invention is characterized in that it absorbs electromagnetic waves in any part of a band from 300 MHz to 30 GHz.

The present invention is also an electromagnetic wave absorber for absorbing electromagnetic waves in the 2.4 GHz band,
The total thickness dimension is 5 mm or less.

Further, the present invention is characterized by having an electromagnetic wave shielding property for shielding electromagnetic waves.
In addition, the present invention is characterized by having flame retardancy, quasi-incombustibility or incombustibility.

Moreover, this invention is a building material provided with the said electromagnetic wave absorber.
Moreover, this invention is an electromagnetic wave absorption method by using the said electromagnetic wave absorber.

  According to the present invention, an electromagnetic wave can be absorbed by causing the conductive pattern body of the pattern layer to function as a receiving antenna to capture an electromagnetic wave and losing the electromagnetic wave energy in the loss layer. Each interior angle is 180 ° or less, and a pattern piece formed in a polygonal shape or an ellipse other than a regular polygonal shape resonates at different frequencies depending on the direction of the electric field of the applied electromagnetic wave, and resonates at different frequencies. . In the electromagnetic wave absorber in which such pattern pieces are arranged in different directions, there are a plurality of resonance modes that resonate at different frequencies regardless of the direction of the electric field of the irradiated electromagnetic wave, and a plurality of discrete frequencies. Can absorb electromagnetic waves. When the resonance frequencies of the modes are adjacent to each other, electromagnetic waves can be absorbed over a relatively wide frequency band.

  Further, according to the present invention, the pattern pieces are arranged so as to have a rotational symmetry of 3 times or more, and in particular, arranged so as to have at least one of the rotational symmetry of 3, 4, or 6 times. As a result, it is possible to generate multiple resonance modes more reliably regardless of the direction of the electric field of the irradiated electromagnetic wave, and to reduce the change in absorption characteristics according to the direction of the electric field of the irradiated electromagnetic wave. Can do.

  In the present invention, the pattern layer has an area ratio in which the area of the region where the conductive pattern body is formed is 0.55 or more when the area of the entire pattern layer region is 1. By forming the pattern layer in the area ratio within the above range, it is possible to increase the amount of electromagnetic wave absorption and increase the bandwidth of the frequency band where the electromagnetic wave absorption amount is large.

  In the present invention, since the pattern piece and the pattern piece formed in a regular polygon or a circle are arranged in combination, the pattern piece may have a plurality of resonance modes that resonate at different frequencies. It is possible to absorb electromagnetic waves at a plurality of discrete frequencies.

  According to the present invention, the conductive pattern body includes a small square pattern piece (hereinafter referred to as “small square piece”), a large square pattern piece (hereinafter referred to as “large square piece”), and a rectangular pattern piece ( (Hereinafter referred to as “rectangular piece”). Thus, the conductive pattern body has a plurality of types of pattern pieces having different shapes and dimensions. Since the frequency of the electromagnetic wave received by the conductive pattern body depends on the shape and size of each pattern piece, by having a plurality of types of pattern pieces having different shapes and dimensions, the electromagnetic wave is absorbed at a plurality of discrete frequencies. It is possible to absorb electromagnetic waves over a relatively wide frequency band. Further, by combining the small square pieces, the large square pieces, and the rectangular pieces, the pattern pieces can be densely arranged so that the region where the conductive pattern body is not formed becomes small. Thereby, the ratio of the area | region where the pattern piece in a pattern layer is formed can be enlarged. By increasing the ratio of the region where the pattern pieces are formed, the amount of electromagnetic wave absorption can be increased, and the bandwidth of the frequency band where the amount of electromagnetic wave absorption is large can be increased. Therefore, it is possible to obtain an excellent electromagnetic wave absorber having at least one of multimodality and broadness and having absorption characteristics with a large absorption amount.

  According to the present invention, the length of the short side of the rectangular piece is the same as the length of one side of the small square piece, and the length of the long side of the rectangular piece is the length of one side of the large square piece. It is the same as the size. By arranging each pattern piece so that the short side of the rectangular piece is opposed to one side of the small square piece and the long side of the rectangular piece is opposed to one side of the large square piece, this allows an area where the pattern piece is not formed. As small as possible, the pattern pieces can be formed side by side as densely as possible.

  Further, according to the present invention, the small square piece and the large square piece are arranged so that the corner portions are abutted with each other, the two rectangular pieces are opposed to the small square piece, and the long side is changed to the large square piece. They are arranged facing each other. Since these four pattern pieces are arranged as a group, the number of small square pieces and the number of large square pieces are made the same, and the area where the pattern pieces are not formed is made as small as possible. Can be formed as closely as possible.

  Further, according to the present invention, the corners of the pattern piece are formed in a curved shape, that is, by giving R to the corners, the amount of absorption of electromagnetic waves (hereinafter referred to as “absorption amount of electromagnetic waves” depending on the polarization direction of electromagnetic waves). ) Can be suppressed to a small frequency deviation, and the polarization characteristics can be improved. Therefore, it is possible to realize an electromagnetic wave absorber having an excellent electromagnetic wave absorption characteristic in which the peak value of the absorption amount is high and the frequency shift at which the absorption amount reaches the peak value depending on the polarization direction of the electromagnetic wave is small.

  All pattern pieces may have a curved corner, but not all pattern pieces may have a curved corner, and some pattern pieces may have curved corners. Any configuration that has When some pattern pieces have curved corners, the other pattern pieces are not limited to the presence or absence of curved corners. Furthermore, the pattern piece having curved corners may be curved at only some corners, or all corners may be curved.

  According to the invention, the pattern layer has an area ratio such that the area of the pattern piece is 0.6 or more when the area of the entire pattern layer region is 1. By forming the pattern layer in the area ratio within the above range, it is possible to increase the amount of electromagnetic wave absorption and increase the bandwidth of the frequency band where the electromagnetic wave absorption amount is large.

  According to the present invention, the loss layer has a layer made of at least one of a magnetic loss material and a dielectric loss material. Therefore, the loss amount of electromagnetic energy captured by the conductive pattern body of the pattern layer is increased, and the electromagnetic wave Can be absorbed with a large absorption amount.

  According to the invention, the loss layer includes at least a layer made of a magnetic loss material and at least a layer made of a dielectric loss material. In this way, both the layer made of magnetic loss material and the layer made of dielectric loss material lose the electromagnetic wave energy captured by the conductive pattern body of the pattern layer, so the loss amount is increased and the electromagnetic wave is absorbed by a large amount of absorption. Can be absorbed.

  Moreover, according to this invention, it functions as a receiving antenna with respect to the electromagnetic waves of two or more arbitrarily different frequencies, and can absorb electromagnetic waves with a large absorption amount.

  Further, according to the present invention, electromagnetic waves other than the basic and higher order resonance frequencies that could not be absorbed by one type of pattern piece can be absorbed with a large absorption amount by the resonance of other pattern pieces.

  Moreover, according to this invention, it functions as a receiving antenna with respect to the electromagnetic wave of the one part band among 300 MHz-30 GHz electromagnetic waves, and can absorb electromagnetic waves with a big absorption amount.

  Further, according to the present invention, the conductive pattern body functions as a receiving antenna with respect to the 2.4 GHz band electromagnetic wave, and can absorb the 2.4 GHz band electromagnetic wave with a large absorption amount. Moreover, the total thickness dimension is 5 mm or less, and a thin electromagnetic wave absorber can be realized. The 2.4 GHz band is a frequency band of 2.4 GHz or more and less than 2.5 GHz.

  Further, according to the present invention, since it has electromagnetic wave shielding properties for shielding electromagnetic waves, a highly convenient electromagnetic wave absorber can be realized.

  Further, according to the present invention, the electromagnetic wave absorber has flame retardancy, quasi-incombustibility or non-flammability, and is suitably used for applications requiring flame retardancy, quasi-incombustibility or incombustibility, for example, building materials. be able to.

  Moreover, according to this invention, the outstanding building material is realizable using the above-mentioned outstanding electromagnetic wave absorber.

  Moreover, according to this invention, electromagnetic waves can be suitably absorbed by using the above-mentioned excellent electromagnetic wave absorber.

  FIG. 1 is a front view showing a part of an electromagnetic wave absorber 1 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a part of the electromagnetic wave absorber 1. FIG. 2 is a cross-sectional view showing a part of the electromagnetic wave absorber 1. FIG. 1 shows the electromagnetic wave incident side, which is the upper side of FIG. The electromagnetic wave absorber 1 is used, for example, to improve an electromagnetic environment in a space such as an office, and absorbs the electromagnetic wave in the space. The electromagnetic wave absorber 1 is a plate having flexibility and can be bent and stretched. The shape of the electromagnetic wave absorber 1 may be a curved surface in a natural state where no external force acts, but in the present embodiment, it is a planar shape. Therefore, the electromagnetic wave absorber 1 has a flat plate shape.

  The electromagnetic wave absorber 1 is a laminate having a plurality of layers as shown in FIG. The electromagnetic wave absorber 1 includes at least a pattern layer 5 and a loss layer 7, and further includes a conductive reflection layer (hereinafter referred to as “reflection layer”) 2 in the present embodiment. In the present embodiment, the pattern layer 5, the loss layer 7, and the reflective layer 2 are laminated in the thickness direction in this order from the electromagnetic wave incident side.

  The pattern layer 5 includes a conductive pattern body (hereinafter referred to as “pattern body”) 12. The pattern body 12 has a resonance frequency that depends on the shape and dimensions, and functions as a receiving antenna that receives electromagnetic waves having the resonance frequency. The pattern layer 5 is configured by forming the pattern body 12 on the surface of the plate-like substrate 11 on the electromagnetic wave incident side (hereinafter referred to as “first substrate surface”). The surface of the first base material is a surface on one side in the thickness direction of the plate-like base material 11.

  The plate-like substrate 11 is made of a dielectric material, and this plate-like substrate 11 also has a loss function similar to that of the dielectric layer 3 in the loss layer 7 described later. The dielectric material may be any material as long as it has electrical insulation, may be a material only of a dielectric, or a material in which a dielectric and a raw material other than the dielectric are mixed. It may be. In the present embodiment, the plate-like substrate 11 is made of a dielectric material only of a dielectric. As a material of the plate-like substrate 11, for example, synthetic resin such as polyethylene terephthalate (PET), paper, wood, glass, or the like can be used.

  The pattern body 12 is made of a conductive material such as metal. As a material of the pattern body 12, for example, gold, platinum, silver, nickel, chromium, aluminum, copper, zinc, lead, tungsten and iron can be used. As materials other than metals, carbon / graphite materials, conductive oxides such as ITO (indium tin oxide) and zinc oxide, and conductive polymers such as polyacetylene can also be used. The pattern body 12 is formed on the plate-like substrate 11 by, for example, vapor deposition, plating, metal foil sticking, etching process thereof, or screen printing.

  FIG. 3 is an enlarged front view showing one pattern group 17 in the pattern body 12. Referring to FIG. 1 and FIG. 3 together, the pattern body 12 is a plurality of pattern pieces provided at intervals, and has a plurality of types of pattern pieces. In the present embodiment, the pattern body 12 includes a small square pattern piece (hereinafter referred to as “small square piece”) 13, a large square pattern piece (hereinafter referred to as “large square piece”) 14, and a rectangular pattern piece (hereinafter referred to as “small square piece”). (Hereinafter referred to as “rectangular pieces”) 15a and 15b. Hereinafter, when one or more of the small square piece 13, the large square piece 14, and the rectangular pieces 15a and 15b are unspecified, it is referred to as a pattern piece.

  The small square piece 13 is a pattern piece that becomes a square in the reference state in which the surface of the first base material is planar, and the length dimension of one side is the first dimension L1. The large square piece 14 is a pattern piece that becomes a square in the reference state, and the length dimension of one side is a second dimension L2 (> L1) larger than the first dimension L1. The rectangular pieces 15a and 15b have a first rectangular piece 15a and a second rectangular piece 15b. The first rectangular piece 15a and the second rectangular piece 15b are pattern pieces that are congruent rectangles that are different in direction from each other in the reference state. The direction of two congruent polygon pattern pieces being different means that the extending directions of the corresponding sides of the polygon pattern pieces are different. The length dimension of each side of the rectangular pieces 15a and 15b is not less than the first dimension L1 and not more than the second dimension L2. In the present embodiment, the length dimension of the short side is the first dimension L1, and the length dimension of the long side of the rectangle is the second dimension L2.

  Each pattern piece 13, 14, 15a, 15b is formed so that each side is parallel to either the x direction or the y direction. The x direction and the y direction are directions along the surface of the first base material of the plate-like base material 11. In the reference state where the first base material surface of the plate-like base material 11 is a flat surface, the x direction and the y direction are perpendicular to each other.

  One small square piece 13, one large square piece 14, one first rectangular piece 15a, and one second rectangular piece 15b are combined, and a pattern group including these four pattern pieces as a group. 17 is configured. A plurality of pattern groups 17 composed of such four pattern pieces are regularly arranged.

  As shown in FIG. 3, in one pattern group 17, the small square pieces 13 and the large square pieces 14 are arranged so that the corner portions are abutted with each other. One diagonal line in the small square piece 13, specifically, a diagonal line 18 connecting the corner portion butted to the large square piece 14 and the opposite corner, and one diagonal line in the large square piece 14, specifically small The small square pieces 13 and the large square pieces 14 are arranged so that the diagonal lines 19 connecting the corners butted to the square pieces 14 and the opposite corners 19 are arranged on the same straight line.

  Further, first and second rectangular pieces 15a and 15b are provided so as to be fitted into substantially triangular recesses on both sides of the small square piece 13 and the large square piece 14 arranged side by side. The first and second rectangular pieces 15 a and 15 b are arranged so that the short side faces one side of the small square piece 13 and the long side faces one side of the large square piece 14. The first rectangular piece 15a is a rectangle whose short side is along the x direction, the short side is opposed to the side along the x direction of the small square piece 13, and the long side is opposed to the side along the y direction of the large square piece 14. I am letting. The second rectangular piece 15b is a rectangle whose short side is along the y direction, the short side is opposed to the side along the y direction of the small square piece 13, and the long side is opposed to the side along the x direction of the large square piece 14. I am letting.

  The small square piece 13, the large square piece 14, the first and second rectangular pieces 15a and 15b are arranged in this way, and one pattern group 17 has a square shape in which each side is parallel to either the x direction or the y direction. It has the shape of In the present embodiment, as shown in FIG. 1, the pattern groups 17 are arranged in a matrix with the same posture, aligned in the x direction and the y direction. Thus, in the pattern body 12, the pattern pieces 13, 14, 15a, and 15b are arranged so as to repeat the arrangement of one pattern group 17, and the pattern body 12 has translational symmetry. Accordingly, the pattern body 12 has the same number of small square pieces 13, large square pieces 14, and first and second rectangular pieces 15a and 15b, respectively, when viewed macroscopically.

  The plurality of first and second rectangular pieces 15a and 15b are provided so as to be spaced apart from each other and arranged in different directions, and are arranged so as to have four-fold rotational symmetry in the present embodiment. . The first and second rectangular pieces 15a and 15b are rotationally symmetric four times around an axis perpendicular to the X direction and the Y direction through the center of the small square piece 13, and pass through the center of the large square piece 14. The rotational symmetry is four times around an axis perpendicular to the X direction and the Y direction.

  The dimension of the pattern body 12 is determined based on the frequency of the electromagnetic wave to be absorbed. The interval D between the adjacent pattern pieces 13, 14, 15a, 15b may be different depending on the location, but may have the same dimensions throughout, and is the same in the present embodiment.

  In such a pattern layer 5, by forming the pattern body 12 as described above, when the area of the entire pattern layer region (hereinafter referred to as “total area”) Sa is 1, a region in which the pattern body 12 is formed. The area ratio (hereinafter referred to as “pattern area”) Sp is 0.6 or more. The total area corresponds to the area of the surface of the first base material of the plate-like base material 11, and the pattern body 12 is formed in a region having an area that occupies 60% or more of the area. Therefore, the value obtained by dividing the pattern area Sp by the area (hereinafter referred to as “non-pattern area”) So of the region where the pattern body 12 is not formed on the first substrate surface is 1.5 or more.

Although the dimension of the pattern body 12 is not limited, for example, the first dimension L1 is 9.5 mm, the second dimension L2 is 24 mm, and the interval D is 4.5 mm. is there. In the pattern body 12 having such dimensions, the following expressions (1) to (5) are established in one pattern group 17. Therefore, when the total area Sa is 1, the pattern area Sp is 0.62, the pattern body 12 is formed in a region occupying 62%, and the value (area ratio) obtained by dividing the pattern area Sp by the non-pattern area So is: 1.64.
Sp = 24 × 24 + 9.5 × 9.5 + 24 × 9.5 × 2
= 1122.25 [mm ² ] (1)
Sa = (24 + 9.5 + 4.5 × 2) ² = 1806.25 [mm ² ] (2)
So = 1806.25-1112.25 = 684 [mm < ² >] ... (3)
Sp / So = 1122.25 / 684 = 1.6407 (4)
Sp / Sa = 1122.25 / 1806.25 = 0.6213 (5)

  The pattern body 12 is not a closed loop linear shape (strip shape) extending along the outer peripheral edge of the above-described shape, but is a planar pattern in which the inner region portion is also painted. Therefore, a capacitor can be formed between the conductive reflective layer 2.

  The loss layer 7 includes a portion made of a material that is at least one of a magnetic loss material having a complex relative permeability (μ ′, μ ″) and a dielectric loss material having a complex relative permittivity (ε ′, ε ″). It is a layer having. The loss layer 7 may be a layer having only a portion made of a material that is a magnetic loss material, a layer having only a portion made of a material that is a dielectric loss material, or a magnetic loss material. It may be a layer having a portion made of a certain material and a portion made of a material that is a dielectric loss material, or may be a layer having a portion made of a material that is a magnetic loss material and is a dielectric loss material.

  In the present embodiment, the loss layer 7 has an electromagnetic wave absorption layer (hereinafter referred to as “absorption layer”) 4 and a dielectric layer 3, and is laminated in the order of the absorption layer 4 and the dielectric layer 3 from the electromagnetic wave incident side. Has been. In the present embodiment, the absorption layer 4 is made of a non-conductive, ie, electrically insulating magnetic material, and the dielectric layer 3 is made of a dielectric material. A magnetic material having electrical insulation is a magnetic loss material and a dielectric loss material. The dielectric material is a dielectric loss material. The loss layer 7 only needs to include at least one layer made of magnetic or dielectric loss material. When the absorption layer 4 is magnetic or dielectric loss material, the dielectric material of the dielectric layer 3 is a low loss material. It may be a low dielectric constant and low loss material such as a foam.

  As the material for forming the absorption layer 4, a material containing a magnetic body having electrical insulation is used. This material may be a material composed only of a magnetic material, or may be a material obtained by mixing a magnetic material and another material. As an example of a material that mixes a magnetic material and another material, for example, a material that mixes a magnetic material and an organic polymer can be used. In addition, other materials such as graphite and carbon fiber can be used in addition to the magnetic material and the organic polymer. Thus, the absorption layer 4 is a layer made of a material containing at least a magnetic substance, and is a layer made of a material that is at least a magnetic loss material. For example, a layer of a sintered body such as ferrite, a metal oxide film, etc. It can be realized by a layer or a layer of a metal polymer film.

  In addition, as a material for forming the absorption layer 4, a material including a dielectric loss material having electrical insulation may be used. This material may be an insulating material such as an organic polymer or an oxide, or may be a non-magnetic metal particle or fiber such as aluminum dispersed in an insulator.

  In the present embodiment, the absorption layer 4 is made of a material obtained by mixing a binder for molding and mixing the binder and magnetic powder as a magnetic material. The binder is made of a dielectric, and the material forming the absorption layer 4 thereby is a magnetic material as described above, and is also a dielectric material. The binder and the magnetic powder are not particularly limited. For example, the following can be used as the binder and the magnetic powder.

(Binder)
Various organic polymers can be used as the material of the binder. For example, polymer materials such as rubber materials, thermoplastic elastomer materials, and various synthetic resin (plastic) materials can be used. Examples of the rubber material include natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, ethylene-propylene rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber (EPDM rubber), ethylene-vinyl acetate rubber, Synthetic rubbers such as butyl rubber, halogenated butyl rubber, chloroprene rubber, nitrile rubber, acrylic rubber, ethylene acrylic rubber, epichlorohydrin rubber, fluorine rubber, urethane rubber, silicon rubber, chlorinated polyethylene rubber, hydrogenated nitrile rubber (HNBR) Etc. Further, derivatives of these rubbers or those modified by various modification treatments may be used.

  These rubber materials may be used alone or as a blend of two or more. In addition to vulcanizing agents, rubber materials that are conventionally used as rubber compounding agents, such as vulcanization accelerators, anti-aging agents, softeners, plasticizers, fillers, and colorants, should be added as appropriate. Can do. Furthermore, additives other than these can be added. For example, in order to control the dielectric constant and conductivity, impedance matching with a predetermined amount of dielectric (carbon black, graphite, titanium oxide, etc.), specifically to the electromagnetic wave to be absorbed, depending on the application of the electromagnetic wave absorber 1 Depending on the temperature environment, the material can be designed and added. Further, processing aids (lubricants, dispersants) may be appropriately selected and added.

  Examples of thermoplastic elastomer materials include chlorinated elastomers such as chlorinated polyethylene, ethylene copolymer elastomers, acrylic elastomers, ethylene acrylic copolymer elastomers, urethane elastomers, ester elastomers, silicone elastomers, and styrene elastomers. Various thermoplastic elastomers such as an elastomer, an amide elastomer, and an olefin elastomer can be used. These elastomer conductors may also be used.

Furthermore, various synthetic resin materials include, for example, chlorine resins such as polyethylene, polypropylene, AS resin, ABS resin, polystyrene, polyvinyl chloride, and polyvinylidene chloride; polyvinyl acetate, ethylene-vinyl acetate copolymer, fluororesin, Examples thereof include thermoplastic resins such as silicone resins, acrylic resins, nylon, polycarbonate, polyethylene terephthalate, alkyd resins, unsaturated polyesters, polysulfones, urethane resins, phenol resins, urea resins, and epoxy resins, and thermosetting resins. Moreover, the derivative | guide_body of these synthetic resin materials may be sufficient.
Further, the bonded body may be any foam of rubber, elastomer, and resin.

  The specific material described above is merely an example of a binder, but such a material can be used. As the binder, low molecular weight oligomer type and liquid type materials can be used. Any material can be selected as long as it is a material that can be formed into a sheet by heat, pressure, ultraviolet rays, a curing agent, and the like.

  In particular, in the present invention, the binder material is at least one material selected from vinyl chloride resins, urethane resins, chlorinated polyethylene resins, styrene-butadiene-styrene (SBS) copolymers, and derivatives thereof. Is preferably used.

(Magnetic powder)
As the magnetic powder, soft magnetic powder is used. Examples of the soft magnetic powder include magnetic stainless steel (Fe—Cr—Al—Si alloy), sendust (Fe—Si—Al alloy), permalloy (Fe—Ni alloy), and silicon copper (Fe—Cu—Si alloy). , Fe—Si alloy, Fe—Si—B (—Cu—Nb) alloy, Fe—Ni—Cr—Si alloy, Fe—Si—Cr alloy, Fe—Si—Al—Ni—Cr alloy, etc. It is done. Further, as the soft magnetic powder, ferrite powder or pure iron powder may be used. Examples of ferrite powder include soft ferrite powder such as Mn—Zn ferrite, Ni—Zn ferrite, Mn—Mg ferrite, Mn ferrite, Cu—Zn ferrite, Cu—Mg—Zn ferrite, Ba—Ni—Co ferrite, or the like. Examples thereof include hard ferrite powder which is a permanent magnet material. Examples of pure iron powder include carbonyl iron powder. The powder includes what are called particles.

  The shape of the magnetic powder is not particularly limited, but may be a spherical shape, a flat shape, a fibrous shape, or the like. The shape of the soft magnetic powder is preferably a spherical or substantially spherical shape because it can be filled at a high filling rate. As these magnetic powders, one kind of powder may be used alone, but a plurality of kinds of powders having different shapes and / or materials may be blended and used. When the magnetic powder is substantially spherical, the average particle size is 0.1 to 500 μm, preferably 1 to 200 μm. When the magnetic powder is flat, the major axis is 0.1 to 500 μm, preferably 1 to 200 μm, and the aspect ratio is 2 to 500, preferably 10 to 100.

  As a material for forming the dielectric layer 3, a material containing a dielectric is used. This material may be a material composed only of a dielectric, or a material in which a dielectric and other materials are mixed. In the present embodiment, the dielectric layer 3 is made of a dielectric material only of a dielectric. As the dielectric forming the dielectric layer 3, for example, synthetic resin, rubber, paper, wood, gypsum, cement and glass can be used. Thus, the dielectric layer 3 is a layer made of a material containing at least a dielectric material and made of at least a dielectric loss material.

  The reflective layer 2 is provided over the entire electromagnetic wave absorber 1. The reflective layer 2 is a layer that has at least conductivity and reflects electromagnetic waves, and is also a layer that prevents transmission of electromagnetic waves and shields electromagnetic waves. The reflection layer 2 can prevent electromagnetic waves that cannot be absorbed by the electromagnetic wave absorber 1 from passing through the electromagnetic wave absorber 1. The electromagnetic wave that cannot be absorbed by the electromagnetic wave absorber 1 is not only an electromagnetic wave having a frequency that should be absorbed, but an electromagnetic wave having a frequency different from the electromagnetic wave having a frequency that should be absorbed, as well as the electromagnetic wave that has not been able to lose energy in the loss layer 7. Is also included. By providing the reflective layer 2 in this manner, the electromagnetic wave absorber 1 has electromagnetic wave shielding properties.

  The reflective layer 2 may be realized by a plate, sheet, film, foil, woven fabric or non-woven fabric made of a conductive material, or a plate, sheet, film, foil made of a mixed material obtained by mixing a conductive material with a synthetic resin. It may be realized by a woven fabric or a non-woven fabric, or may be realized by a plate, sheet, film, foil, woven fabric or non-woven fabric in which a conductive film made of a conductive material is formed on a base material made of a synthetic resin or the like. Good. Examples of the method for forming the conductive film on the substrate include plating, vapor deposition (sputtering), and printing. The conductive material forming the reflective layer 2 may be a metal or a material other than a metal such as carbon. As a metal for forming the reflective layer 2, a metal that can be used for forming the pattern body 12 can be used in the same manner. In the present embodiment, the reflective layer 2 is configured by forming a metal film over the entire surface on the electromagnetic wave incident side surface of the plate-like substrate.

  The electromagnetic wave absorber 1 receives an electromagnetic wave having a resonance frequency determined by the pattern body 12 of the pattern layer 5 depending on the shape and size thereof, stores electromagnetic wave energy between the pattern body 12 and the reflective layer 2, and The electromagnetic wave energy is lost in the loss layer 7 including the absorption layer 4 and the dielectric layer 3. The loss of electromagnetic energy is caused by the conversion of electromagnetic energy into thermal energy.

  In the electromagnetic wave absorber 1, a part of the irradiated electromagnetic wave is reflected on the surface, and the rest enters the electromagnetic wave absorber 1 from between the pattern pieces 13, 14, 15 a and 15 b. Inside the electromagnetic wave absorber 1, the electromagnetic wave propagates while being attenuated, and a part is re-radiated from between the pattern pieces 13, 14, 15 a and 15 b. The phase of the re-radiated wave differs from the phase of the surface reflected wave by the amount of the path propagated in the electromagnetic wave absorber 1, and the surface reflected wave and the re-radiated wave are opposite in phase at the resonance frequency of each pattern piece 13, 14, 15a, 15b. And cancel each other. In the pattern body 12, the pattern pieces 13, 14, 15 a, and 15 b resonate at different frequencies, and the electromagnetic wave absorber 1 in which interference between the surface reflected wave and the re-radiated wave cancels near each resonance frequency occurs in the electromagnetic wave absorber 1. The intensity of the reflected wave can be reduced by the mutual interference.

  As described above, the electromagnetic wave absorber 1 efficiently reduces the reflection due to electromagnetic wave interference using the pattern layer 5 and efficiently takes in electromagnetic energy into the absorber, and uses the loss (converted into thermal energy) by the loss layer 7. Absorbs electromagnetic waves. The electromagnetic wave absorber 1 can efficiently receive an electromagnetic wave by using the pattern layer 5 and the loss layer 7, and can efficiently absorb the electromagnetic wave by the energy conversion described above.

  The frequency of the electromagnetic wave absorbed by the electromagnetic wave absorber 1 depends on the shape, size and interval of the pattern body 12 and also on the thickness of the loss layer 7, and thus on the absorption layer 4 and the dielectric layer 3. And the dimensions are selected and determined. The frequency of the electromagnetic wave to be absorbed by the electromagnetic wave absorber 1 is not particularly limited, but may be a frequency in the range of 300 kHz to 3000 GHz. The electromagnetic wave absorber 1 is, for example, particularly in the UHF band (860 MHz or more and less than 960 MHz), 2.4 GHz band (2.4 GHz or more and less than 2.5 GHz), 5 GHz band (5.15 GHz or more and less than 5.35 GHz, 5.47 GHz or more and 5. (Less than 725 GHz) and 5.8 GHz band (5.725 GHz or more and less than 5.875 GHz) are used to absorb electromagnetic waves.

  The first dimension L1 is, for example, not less than 10 mm and not more than 45 mm, and the second dimension L2 is, for example, not less than 5 mm and not more than 27 mm. The distance D between the adjacent pattern pieces 13, 14, 15a, 15b has the same dimension throughout, and is not less than 0.5 mm and not more than 10 mm, for example, 2 mm. The thickness dimension of the absorption layer 4 is, for example, 0.2 mm or more and 4.0 mm or less, and the thickness dimension of the dielectric layer 3 is, for example, 1.5 mm or more and 7.0 mm or less. These dimensions are merely examples, and are not limited thereto.

  The electromagnetic wave absorber 1 has flame retardancy, quasi-incombustibility, or incombustibility. The standard for flame retardancy is to obtain an evaluation of UL94V0. Although the use of the electromagnetic wave absorber 1 is not limited, for example, it is used as a constituent member of a building material. The electromagnetic wave absorber 1 having flame retardancy, quasi-incombustibility or incombustibility can suitably constitute a building material. The building material is a material used for erection of a building, for example, an interior material, a wall material, a floor material, a screen material, a top plate material, and a surface material. When imparting flame retardancy, quasi-incombustibility, or incombustibility to the electromagnetic wave absorber 1, for example, a flame retardant or a flame retardant aid is added to the electromagnetic wave absorber 1. A flame retardant or a flame retardant aid is added to the absorption layer 4 and the dielectric layer 3, for example.

  As the flame retardant, known ones can be used alone or blended. As the flame retardant, for example, a phosphorus compound flame retardant, a boron compound, a halogen flame retardant, a zinc flame retardant, a nitrogen flame retardant, and a hydroxide flame retardant can be used. Examples of phosphorus compound-based flame retardants include phosphate esters. Examples of the halogen-based flame retardant include a brominated flame retardant. Examples of the zinc flame retardant include zinc carbonate and zinc borate. Examples of nitrogen flame retardants include triazine compounds, hindered amine compounds, and melamine compounds. Examples of the hydroxide flame retardant include magnesium hydroxide and aluminum hydroxide. Moreover, as a flame retardant aid, carbon black, a fatty acid metal salt, or the like can be used. These flame retardants and flame retardant aids are used for blending and designing to achieve flame retardancy such as UL94 V0.

  According to such an electromagnetic wave absorber 1, the rectangular pieces 15 a and 15 b each having an inner angle of 180 ° or less and having a polygonal shape excluding the regular polygonal shape resonate depending on the direction of the electric field of the irradiated electromagnetic wave. Differ and resonate at different frequencies. When such rectangular pieces 15a and 15b are arranged in different directions, the resonance modes can be made different among the plurality of rectangular pieces 15a and 15b regardless of the direction of the electric field of the electromagnetic wave to be irradiated. It is possible to absorb electromagnetic waves at a frequency of 1 and to absorb electromagnetic waves over a relatively wide frequency band, and to reduce the change in absorption characteristics according to the direction of the electric field of the irradiated electromagnetic waves. In addition, since the plurality of rectangular pieces 15a and 15b are arranged so as to have a rotational symmetry of three times or more, the directions of the rectangular pieces 15a and 15b can be surely changed, and the rotational symmetry can be made four times. By arranging, the pattern pieces can be arranged closely when the small square pieces 13 and the large square pieces 14 are combined.

The pattern body 12 includes a small square piece 13, a large square piece 14, and rectangular pieces 15a and 15b. Thus, the pattern body 12 has a plurality of types of pattern pieces having different shapes and dimensions. Since the frequency of the electromagnetic wave received by the pattern body 12 depends on the shape and size of each pattern piece 13, 14, 15a, 15b, two or more arbitrary patterns can be obtained by having a plurality of types of pattern pieces having different shapes and dimensions. It functions as a receiving antenna for electromagnetic waves of different frequencies, and can absorb electromagnetic waves at a plurality of discrete frequencies, and can absorb electromagnetic waves over a relatively wide frequency band.
In addition, since the pattern layer 5 includes a plurality of pattern pieces, the basic resonance frequency and the higher-order resonance frequency by one pattern piece are different from the basic resonance frequency by at least one pattern piece among the other pattern pieces. Electromagnetic waves other than the basic and higher order resonance frequencies that could not be absorbed by the type of pattern pieces can be absorbed with a large absorption amount due to the resonance of other pattern pieces.

  Further, by combining the small square piece 13, the large square piece 14, and the rectangular pieces 15a, 15b, the pattern pieces 13, 14, 15a, 15b can be formed closely arranged. As a result, the pattern area can be increased, the amount of electromagnetic wave absorption can be increased, and the bandwidth of a frequency band with a large amount of electromagnetic wave absorption can be increased. Therefore, it is possible to obtain an excellent electromagnetic wave absorber 1 having at least one of multimodality and broadness and having absorption characteristics with a large absorption amount.

  In particular, as described above, the length dimension of the short sides of the rectangular pieces 15a and 15b is the same as the length dimension of one side of the small square pieces 13, and the length dimension of the long sides of the rectangular pieces 15a and 15b is large. It is the same as the length of one side of the square piece 14, and by arranging as shown in FIG. 3, the number of the pattern pieces 13, 14, 15a, 15b is made the same, and the pattern pieces are made as dense as possible. The pattern area can be increased as much as possible.

  In this way, it is possible to realize the pattern layer 5 in which the pattern area has an area ratio of 0.6 or more when a plurality of types of pattern pieces 13, 14, 15a, 15b are combined and the total area is 1. . By forming the area ratio of the pattern layer 5 in the above range, it is possible to increase the amount of absorption of electromagnetic waves and increase the bandwidth of the frequency band where the amount of absorption of electromagnetic waves is large. In the electromagnetic wave absorber 1, the loss layer 7 includes the absorption layer 4 and the dielectric layer 3, and the energy of the electromagnetic wave captured by the pattern body 12 is lost in both the absorption layer 4 and the dielectric layer 3. Therefore, the loss amount can be increased and electromagnetic waves can be absorbed with a large absorption amount.

  The electromagnetic wave absorber 1 has a reflective layer 2 that functions as an electromagnetic wave shielding plate. Thereby, the electromagnetic wave absorber 1 has an electromagnetic wave shielding property for shielding electromagnetic waves. Therefore, the electromagnetic wave absorber 1 can not only absorb the electromagnetic wave but also shield the electromagnetic wave, and the convenience is improved. Further, in the configuration without the reflective layer 2, the impedance of the pattern body 12 functioning as a receiving antenna changes depending on whether or not an object made of a conductive material exists in the vicinity of the electromagnetic wave absorber 1, and also due to the difference in conductivity. However, although the frequency of the receivable electromagnetic wave changes, in the configuration including the reflective layer 2, it is possible to eliminate the influence of an object made of a conductive material existing near the back surface of the absorber. The convenience is also improved. The reflection layer 2 is also configured to generate electromagnetic interference that plays a role in absorbing electromagnetic waves as described above, and contributes to increasing the amount of electromagnetic waves absorbed. This electromagnetic wave absorber 1 has excellent electromagnetic wave absorption characteristics.

  FIG. 4 is a front view showing a part of an electromagnetic wave absorber 1A according to another embodiment of the present invention. This embodiment is similar to the above-described embodiment shown in FIGS. 1 to 3, and corresponding portions are denoted by the same reference numerals, and only different structures will be described. In the embodiment of FIGS. 1 to 3, the pattern groups 17 are arranged in a matrix with the same posture, but in this embodiment, one posture, for example, the posture of FIGS. And a total of four posture pattern groups 17 of three postures different from the reference posture are regularly arranged.

  As shown in FIG. 4, in this embodiment, in addition to the reference posture, a posture reversed in the x direction, a posture reversed in the y direction, and a posture reversed in the x direction and the y direction are added. . More specifically, a reference posture pattern group 17 is provided every other x direction and y direction, and a pattern group of postures reversed in the x direction is adjacent to the reference posture pattern group 17 in the x direction. The pattern groups of postures reversed in the y direction are arranged adjacent to the reference direction pattern group 17 in the y direction, and the remaining positions in the x direction and the y direction are arranged in the x direction and the y direction. A pattern group 17 having a posture reversed to the above is provided. Regarding the pattern group 17 of the reference posture, a pattern group 17 of postures reversed in the x direction and the y direction is provided adjacent to two oblique directions forming 45 degrees with respect to the x direction and the y direction. Therefore, in this embodiment, the pattern groups 17 in the four postures are adjacent to the adjacent pattern group 17 between the small square pieces 13, the large square pieces 14, the first rectangular pieces 15 a, and the second rectangular pieces 15 b. They are arranged so that they meet each other.

  Also in the pattern body 12 in the present embodiment, the pattern pieces 13, 14, 15a, and 15b are arranged so as to repeat the arrangement of one pattern group 17, and the pattern body 12 has translational symmetry. . Also in the present embodiment, the first and second rectangular pieces 15a and 15b have four-fold rotational symmetry. The first and second rectangular pieces 15a and 15b pass through the center of the region surrounded by the four small square pieces 13 and are rotationally symmetric four times around the axis perpendicular to the X and Y directions. The rotational symmetry is four times around an axis perpendicular to the X direction and the Y direction through the center of the region surrounded by the large square piece 14.

  As described above, the pattern layer 5 in FIG. 4 in which the pattern pieces 13, 14, 15 a, and 15 b are arranged differently can be used in place of the pattern layer 5 in FIGS. 1 to 3. Even with such a configuration, it is possible to achieve the same effects as those of the above-described embodiment.

  The arrangement of the pattern group 17 shown in FIGS. 1 and 4 is merely an example, and other arrangements may be used. For example, two of the four postures described above may be selected, and the pattern groups 17 of these two postures may be arranged in a checkered pattern. Alternatively, the pattern groups 17 may be arranged in a staggered pattern. Even if the arrangement is changed in this way, the same effect as in the above-described embodiment can be achieved.

  FIG. 5 is a front view showing a part of an electromagnetic wave absorber 1D according to still another embodiment of the present invention. This embodiment is similar to the embodiment shown in FIGS. 1 to 4 described above, and corresponding portions are denoted by the same reference numerals, and only different configurations will be described. In the embodiment shown in FIGS. 1 to 4, the pattern group 17 includes one small square piece 13, one large square piece 14, one first rectangular piece 15a, and one second rectangular piece 15b. In the present embodiment, the pattern group 17 is configured by combining the two first rectangular pieces 15a and the two second rectangular pieces 15b.

  As shown in FIG. 5, the first rectangular piece 15a is a rectangle whose long side is parallel to the y direction, and the second rectangular piece 15b is a rectangle whose long side is parallel to the x direction. The first rectangular piece 15a and the second rectangular piece 15b are pattern pieces that are congruent rectangles that are different in direction from each other in the reference state. The first rectangular pieces 15a and the second rectangular pieces 15b are arranged in a checkered pattern. That is, each short side of the first rectangular piece 15a is opposed to a central portion of the long side of the second rectangular piece 15b, and a central portion of each long side of the first rectangular piece 15a is short of the second rectangular piece 15b. Opposite the center of the side. The first rectangular piece 15a and the second rectangular piece 15b adjacent in the X direction are arranged so that the centers in the Y direction are aligned in the X direction, and the first rectangular piece 15a and the second rectangular piece 15b adjacent in the Y direction are Are arranged so that the centers in the X direction are aligned in the Y direction. In the present embodiment, the distance D between the first rectangular piece 15a and the second rectangular piece 15b adjacent to each other has the same dimension throughout.

  The pattern group 17 includes one first rectangular piece 15a, two second rectangular pieces 15b adjacent to one of the first rectangular piece 15a in the X direction and one of the Y direction, and the two second rectangular pieces. 15b is combined with a first rectangular piece 15a having a long side and a short side facing each other. The pattern body 12 has a plurality of pattern groups 17 regularly arranged and has translational symmetry. The first and second rectangular pieces 15a and 15b included in the pattern group 17 are provided to be separated from each other and have four-fold rotational symmetry. As described above, when the first and second rectangular pieces 15a and 15b are aligned and arranged, the first and second rectangular pieces 15a and 15b included in one pattern group 17 are the first and second rectangular pieces. It passes through the center of the region surrounded by the pieces 15a and 15b, and is rotationally symmetric four times around the axis perpendicular to the X and Y directions.

  The dimension of the pattern body 12 is not limited. For example, the first dimension L1 which is the length of the short sides of the first and second rectangular pieces 15a and 15b is 21 mm. The second dimension L2, which is the length dimension of the long sides of the first and second rectangular pieces 15a, 15b, is 9.5 mm, and the distance D is 1 mm. In the pattern body 12 having such dimensions, when the total area Sa is 1, the pattern area Sp is 0.55 or more. Thus, in the pattern layer having only the rectangular piece as in the present embodiment, the pattern area Sp can be 0.55 or more, and the pattern layer is formed in the area ratio in the above range, The amount of electromagnetic wave absorption can be increased, and the frequency band with a large amount of electromagnetic wave absorption can be increased.

  As described above, the pattern layer 5 of FIG. 5 in which the pattern pieces 15a and 15b are arranged differently can be used in place of the pattern layer 5 of FIGS. Even with such a configuration, it is possible to achieve the same effects as those of the above-described embodiment.

  FIG. 6 is a front view showing a part of an electromagnetic wave absorber 1E according to still another embodiment of the present invention. This embodiment is similar to the embodiment shown in FIGS. 1 to 5 described above, and corresponding portions are denoted by the same reference numerals, and only different configurations will be described. The shape of the pattern pieces is different between the present embodiment and the embodiment of FIG. 5, and in the embodiment of FIG. 5, the pattern group 17 includes two first rectangular pieces 15a and two second rectangular pieces 15b. In the present embodiment, the pattern group 17 is configured by combining the two first oval pieces 15c and the two second oval pieces 15d. The first and second elliptical pieces 15c and 15d are made of the same material as the first and second rectangular pieces 15a and 15b.

  As shown in FIG. 6, the first ellipse piece 15c is an ellipse whose major axis is parallel to the y direction, and the second ellipse piece 15d is an ellipse whose major axis is parallel to the x direction. The first oval piece 15c and the second oval piece 15d are pattern pieces that are congruently elliptical in different directions but in the reference state. The direction of two congruent elliptical pattern pieces being different means that the major axis and the minor axis extending directions of the respective elliptical pattern pieces are different. The first oval piece 15c and the second oval piece 15d are arranged in a checkered pattern. That is, the respective ends in the major axis direction of the first elliptical piece 15c are opposed to the ends in the minor axis direction of the second rectangular piece 15b, and the respective ends in the minor axis direction of the first elliptical piece 15c. The part faces the end of the second elliptical piece 15d in the short axis direction. The first oval piece 15c and the second oval piece 15d adjacent in the x direction are arranged so that the centers in the y direction are aligned in the x direction, that is, the major axis and the minor axis are linearly arranged in the x direction. Are arranged as follows. The first oval piece 15c and the second oval piece 15d adjacent in the y direction are arranged so that the centers in the x direction are aligned in the y direction, that is, the short axis and the long axis are linear in the x direction. Arranged side by side. In the present embodiment, the distance D between the first oval piece 15c and the second oval piece 15d adjacent to each other in the x direction and the y direction is the same dimension throughout.

  The pattern group 17 includes one first oval piece 15c, two second oval pieces 15d adjacent to one of the first oval piece 15c in the X direction and one of the Y direction, and the two second oval pieces 15c. The two elliptical pieces 15d are combined with a first elliptical piece 15c having a major axis end and a minor axis end facing each other.

  The pattern body 12 has a plurality of pattern groups 17 regularly arranged and has translational symmetry. The first and second elliptical pieces 15c and 15d included in the pattern group 17 are provided to be separated from each other and have four-fold rotational symmetry. The four first and second elliptical pieces 15c and 15d included in the pattern group 17 pass through the center of the region surrounded by the four first and second rectangular pieces 15a and 15b, and in the X direction and the Y direction. There are four rotational symmetry around the vertical axis.

  The dimension of the pattern body 12 is not limited. For example, the first dimension L1 which is the length dimension in the major axis direction of the first and second elliptical pieces 15c is 27.5 mm. The second dimension L2, which is the length dimension in the minor axis direction of the first and second elliptical pieces 15c, 15d, is (10) mm, and the distance D is 1 mm. In the pattern body 12 having such dimensions, when the total area Sa is 1, the pattern area Sp is 0.55 or more. Thus, in the pattern layer having only the elliptical piece as in the present embodiment, the pattern area Sp can be set to 0.55 or more, and the pattern layer is formed in the area ratio in the above range. In addition to increasing the amount of electromagnetic waves absorbed, the bandwidth of the frequency band having a large amount of electromagnetic waves absorbed can be increased.

  Thus, the pattern layer 5 of FIG. 6 in which the shape and arrangement of the pattern pieces are different can be used in place of the pattern layer 5 of FIGS. Even with such a configuration, it is possible to achieve the same effects as those of the above-described embodiment. Further, by making the shape of the pattern piece an ellipse, it is possible to suppress the frequency shift at which the amount of absorption of the electromagnetic wave reaches the peak value depending on the polarization direction of the electromagnetic wave, and to improve the polarization characteristic. Therefore, it is possible to realize an electromagnetic wave absorber having excellent electromagnetic wave absorption characteristics with a small frequency shift at which the electromagnetic wave absorption amount reaches a peak value depending on the polarization direction of the electromagnetic wave.

  FIG. 7 is a front view showing a part of an electromagnetic wave absorber 1F according to still another embodiment of the present invention. This embodiment is similar to the above-described embodiment shown in FIGS. 1 to 6, and corresponding portions are denoted by the same reference numerals, and only different structures will be described. Only the shape of each pattern piece 13, 14, 15a, 15b differs between this Embodiment and Embodiment of FIGS. 1-3. The shape of each pattern piece 13, 14, 15a, 15b of the present embodiment is the same as that of each pattern piece 13, 14, 15a, 15b in the embodiment of FIGS. , 15b are curved in a convex shape outward. The radius of curvature R of each corner is selected to be less than or equal to one half of each side of the rectangle when the corner is a right angle, and is preferably about one quarter of each side although it varies depending on the material and configuration.

  By forming the corners of the pattern pieces 13, 14, 15a, 15b in a curved shape, that is, by giving R to the corners, the frequency at which the electromagnetic wave absorption reaches a peak value depending on the polarization direction of the electromagnetic waves. The deviation can be kept small and the polarization characteristics can be improved. Therefore, it is possible to realize an electromagnetic wave absorber having an excellent electromagnetic wave absorption characteristic in which the peak value of the absorption amount is high and the frequency shift at which the absorption amount reaches the peak value depending on the polarization direction of the electromagnetic wave is small.

  Although all the pattern pieces 13, 14, 15a, 15b may have a curved corner as in the present embodiment, some of the pattern pieces 13, 14, 15a, 15b are curved. What is necessary is just the structure which has a shape corner | angular part. For example, the pattern pieces 13 and 14 may have curved corners, the pattern pieces 15a and 15b may have right-angle corners, and the pattern pieces 13 and 14 have right-angle corners, for example. The pattern pieces 15a and 15b may have a curved corner. Thus, when some pattern pieces have curved corners, the other pattern pieces are not limited to the presence or absence of curved corners. Furthermore, the pattern piece which has a curved corner | angular part may be curvilinear, and all the corner | angular parts may be curvilinear.

  Thus, the pattern layer 5 of FIG. 7 in which the shape and arrangement of the pattern pieces are different can be used in place of the pattern layer 5 of FIGS. Even with such a configuration, it is possible to achieve the same effects as those of the above-described embodiment.

  In the present embodiment, the corners of the pattern pieces 13, 14, 15a and 15b of the embodiment shown in FIGS. 1 to 3 are curved, but the pattern pieces of any of the above-described embodiments. As for 13, 14, 15a and 15b, the corners may be formed in a curved shape, and the corners may be formed in a curved shape in the pattern pieces of the embodiments described below.

  FIG. 8 is a front view showing a part of an electromagnetic wave absorber 1G according to still another embodiment of the present invention. This embodiment is similar to the embodiment shown in FIGS. 1 to 7 described above, and corresponding portions are denoted by the same reference numerals, and only different configurations will be described. In the embodiment of FIGS. 1 to 3, the pattern group 17 includes one small square piece 13, one large square piece 14, one first rectangular piece 15a, and one second rectangular piece 15b. In the present embodiment, the pattern group 17 is composed of one small circular piece 13a, one large circular piece 14a, one first oval piece 15c, and one second oval. The shape piece 15d is combined.

  The small circular piece 13a is a pattern piece having a circular shape in the reference state in which the surface of the first base material is planar, and the diameter is the first dimension L1. The large circular piece 14a is a pattern piece that becomes a square in the reference state, and the dimension of the diameter is the second dimension L2 (> L1) larger than the first dimension L1. The first oval piece 15c and the second oval piece 15d are pattern pieces that are congruently elliptical in different directions but in the reference state. The length dimension in the major axis direction of the first and second elliptical pieces 15c, 15d is not less than the first dimension L1 and not more than the second dimension L2. In the present embodiment, the length dimension in the minor axis direction of the first and second elliptical pieces 15c, 15d is the first dimension L1, and the length dimension in the major axis direction is the second dimension L2.

  As shown in FIG. 8, in one pattern group 17, the long axis of the first oval piece 15c extends in the y direction, and the long axis of the second oval piece 15d extends in the x direction. The center of the small circular piece 13a is provided at the intersection of the extended lines of the long axes of the first and second elliptical pieces 15c and 15d, and the short axis of each of the first and second elliptical pieces 15c and 15d is provided. The center of the large circular piece 14a is provided on the intersection of the extension lines.

  By arranging the pattern groups 17 so as to be repeated, in the pattern body 12, small circular pieces 13a are arranged between the first oval pieces 15c in the y direction, and each second oval piece in the y direction. A large circular piece 14a is disposed between 15d, a large circular piece 13b is disposed between each first elliptical piece 15c in the x direction, and a small circular piece is disposed between each second elliptical piece 15d in the x direction. 13a is arranged and has translational symmetry. Accordingly, when viewed macroscopically, the pattern body 12 has the same number of small circular pieces 13a, large circular pieces 14a, and first and second elliptical pieces 15c and 15d.

  The plurality of first and second elliptical pieces 15c and 15d are provided to be separated from each other and have four-fold rotational symmetry. The first and second elliptical pieces 15c, 15d pass through the center of the small circular piece 13a and are rotationally symmetric four times around the axis perpendicular to the X direction and the Y direction. As shown, the rotational symmetry is four times around the axis perpendicular to the X and Y directions.

  Although the dimension of the pattern body 12 is not limited, for example, the length dimension in the major axis direction of the first and second elliptical pieces 15c and 15d and the diameter of the small circular piece 13a are described. The first dimension L1 is 9 mm, the second dimension L2 which is the length dimension in the minor axis direction of the first and second elliptical pieces 15c and 15d and the diameter of the large circular piece 14a is 26 mm, and the distance D Is 2 mm. In the pattern body 12 having such dimensions, when the total area Sa is 1, the pattern area Sp is 0.6 or more.

  Thus, the pattern layer 5 of FIG. 8 in which the shape of each pattern piece is different can be used in place of the pattern layer 5 of FIGS. Even with such a configuration, it is possible to achieve the same effects as those of the above-described embodiment.

  FIG. 9 is a front view showing a part of an electromagnetic wave absorber 1G according to still another embodiment of the present invention. This embodiment is similar to the embodiment shown in FIGS. 1 to 7 described above, and corresponding portions are denoted by the same reference numerals, and only different configurations will be described. The shape of each pattern piece is different between the present embodiment and the embodiment of FIGS. The pattern body 12 of the present embodiment has translational symmetry and has a plurality of rhombus pieces 15e. The rhombus piece 15e is a pattern piece that becomes a rhombus in the reference state in which the surface of the first base material is planar.

  The plurality of rhombus pieces 15e are pattern pieces that are congruent rhombus even when the directions are different from each other in the reference state. The plurality of rhombus pieces 15e are provided so as to be spaced apart from each other, and are arranged so as to have three or six rotational symmetry. At least three of the plurality of rhombus pieces 15e are provided such that obtuse angles of the rhombus pieces 15e are close to each other, and an extension line obtained by extending the shorter diagonal line of the two diagonal lines of each rhombus intersects at one point. Through the points where the intersecting lines of the extension lines intersect, the rotational symmetry is three times around the axis perpendicular to the X direction and the Y direction. In addition, at least six of the plurality of rhombus pieces 15e are provided so that the acute angles of the rhombus pieces 15e are close to each other, and an extension line obtained by extending the longer diagonal line of the two diagonal lines of each rhombus intersects at one point. In addition, it passes through the point of intersection of the extension lines and has six rotations around the axis perpendicular to the X and Y directions.

  9 can be used instead of the pattern layer 5 in FIGS. 1 to 8. Even with such a configuration, it is possible to achieve the same effects as those of the above-described embodiment. In the present embodiment, the pattern piece is a rhombus, but the same effect can be achieved by using a parallelogram.

  FIG. 10 is a front view showing a part of an electromagnetic wave absorber 1J according to still another embodiment of the present invention. This embodiment is similar to the above-described embodiment shown in FIGS. 1 to 9, and corresponding portions are denoted by the same reference numerals, and only different structures will be described. The arrangement of the pattern pieces is different between the present embodiment and the embodiments of FIGS. The pattern body of the present embodiment has a plurality of rhombus pieces 15 e and a plurality of square pieces 21. The square piece 21 is a pattern piece that becomes a square in the reference state in which the surface of the first base material is planar.

  In the pattern body 12, each side of one square piece 21 is arranged with each side of the rhombus piece 15 e facing each other. That is, one side of one square piece 21 is provided with one side of one rhombus piece 15e and spaced apart by a distance D. The lengths of the opposing sides of the square piece 21 and the rhombus piece 15e are formed substantially equal. The four rhombus pieces 15e having sides opposite to the sides of the square piece 21 are provided so as to be separated from each other and have four-fold rotational symmetry. The rhombus piece 15e passes through the center of the square piece 21 and has four-fold rotational symmetry about an axis perpendicular to the X direction and the Y direction.

  Thus, the pattern layer 5 of FIG. 10 in which the shape and arrangement of the pattern pieces are different can be used in place of the pattern layer 5 of FIGS. Even with such a configuration, it is possible to achieve the same effects as those of the above-described embodiment. In the present embodiment, the pattern pieces are rhombuses, but two types of square pieces having different sizes may be provided for each region surrounded by four rhombus pieces 15e as parallelograms.

  FIG. 11 is a front view showing a part of an electromagnetic wave absorber 1K according to still another embodiment of the present invention. This embodiment is similar to the embodiment shown in FIGS. 1 to 10 described above, and corresponding portions are denoted by the same reference numerals, and only different configurations will be described. In the present embodiment, the pattern group 17 is configured by combining one square piece 21 and two hexagonal pieces 22a and 22b. The hexagonal pieces 22a and 22b have a first hexagonal piece 22a and a second hexagonal piece 22b. The first hexagonal piece 22a and the second hexagonal piece 22b are pattern pieces that are congruent rectangles in different directions from each other in the reference state. The hexagonal pieces 22a and 22b are polygonal pattern pieces in the reference state in which the surface of the first base material is flat, and each inner angle is 180 ° or less, and is a shape excluding a regular hexagon. It is. The first and second hexagonal pieces 22a and 22b pass through the center of the first and second hexagonal pieces 22a and 22b. The first and second hexagonal pieces 22a and 22b are formed in two rotational symmetry about the axis parallel to the x and y directions. Among the hexagonal pieces 22a and 22b, the length of two parallel sides is the seventh dimension L7, and the length of the other pieces is an eighth dimension L8 (<L7) smaller than the seventh dimension L7. is there. The side of the seventh dimension L7 is referred to as a long side.

  The long side of the first hexagonal piece 22 a is parallel to the y direction and faces one side of the square piece 21. The long side of the first hexagonal piece 22a and one side of the square piece 21 facing the long side are arranged with a gap D therebetween. The long side of the second hexagonal piece 22b is parallel to the x direction and faces one side of the square piece 21. The long side of the second hexagonal piece 22b and one side of the square piece 21 facing the long side are arranged with a gap D therebetween. The side of the first hexagonal piece 22a that faces the second hexagonal piece 22b and the side of the second hexagonal piece 22b that faces the first hexagonal piece 22a are parallel to each other, and a distance D is provided.

  In the present embodiment, as shown in FIG. 11, the pattern groups 17 are arranged in a matrix with the same posture, aligned in the x direction and the y direction. Thus, in the pattern body 12, each pattern piece 21,22a, 22b is arranged so that the arrangement of one pattern group 17 may be repeated, and the pattern body 12 has translational symmetry.

  The plurality of first and second hexagonal pieces 22a and 22b are provided so as to be spaced apart from each other and are arranged so as to have four-fold rotational symmetry. The first and second hexagonal pieces 22a and 22b pass through the center of the square piece 21 and are rotationally symmetric four times around an axis perpendicular to the X direction and the Y direction. The rotational symmetry is four times around an axis perpendicular to the X direction and the Y direction through the center of the region surrounded by the two hexagonal pieces 22a and 22b.

  As described above, the pattern layer 5 of FIG. 11 in which the pattern pieces are arranged differently can be used in place of the pattern layer 5 of FIGS. 1 to 10. Even with such a configuration, it is possible to achieve the same effects as those of the above-described embodiment.

  FIG. 12 is a cross-sectional view showing a part of an electromagnetic wave absorber 1B according to another embodiment of the present invention. This embodiment is similar to the above-described embodiment shown in FIGS. 1 to 11, and corresponding portions are denoted by the same reference numerals, and only different structures will be described. In this embodiment, the absorbing layer 4, the pattern layer 5, the dielectric layer 3, and the conductive reflective layer 2 are laminated in this order from the electromagnetic wave incident side, which is the upper side of FIG. The pattern layer 5 shown in FIGS. 1 to 3 or the pattern layer 5 shown in FIGS. 4 to 11 may be used. The pattern pieces 13, 14, 15 a, and 15 b may be The pattern layer 5 other than these arrangements may be used. Other configurations are the same as those of the above-described embodiment. In this manner, the absorption layer 4 may be provided on the electromagnetic wave incident side of the pattern layer 5 and the pattern layer 5 may be sandwiched between the loss layer 7. Even with such a configuration, it is possible to achieve the same effects as those of the above-described embodiment.

  FIG. 13 is a cross-sectional view showing a part of an electromagnetic wave absorber 1C according to still another embodiment of the present invention. This embodiment is similar to the above-described embodiment shown in FIGS. 1 to 11, and corresponding portions are denoted by the same reference numerals, and only different structures will be described. In this embodiment, the surface layer 6 is formed on the electromagnetic wave incident side which is the upper side of FIG. The surface layer 6 is a layer made of a material that is at least one of a magnetic loss material and a dielectric loss material, and constitutes the loss layer 7. The surface layer 6 may be either the absorption layer 4 or the dielectric layer 3, or may be another layer. The pattern layer 5 shown in FIGS. 1 to 3 or the pattern layer 5 shown in FIGS. 4 to 11 may be used. The pattern pieces 13, 14, 15 a, and 15 b may be The pattern layer 5 other than these arrangements may be used. Other configurations are the same as those of the above-described embodiment. In this way, the surface layer 6 may be provided on the electromagnetic wave incident side of the pattern layer 5 and the pattern layer 5 may be sandwiched between the loss layer 7. Even with such a configuration, it is possible to achieve the same effects as those of the above-described embodiment.

  The electromagnetic wave absorber of the present invention only needs to have a configuration including a pattern layer and a loss layer, and the stacked configuration is not limited to the stacked configurations shown in FIGS. 2, 12, and 13. As an embodiment of the present invention, for example, a configuration in which the dielectric layer 3, the absorption layer 4, the pattern layer 5, the absorption layer 4, the dielectric layer 3, and the reflection layer 2 are arranged in this order from the electromagnetic wave incident side is also possible. Furthermore, as an embodiment of the present invention, the order from the electromagnetic wave incident side includes a laminate of the pattern layer 5, the absorption layer 4, and the reflective layer 2, a laminate of the pattern layer 5, the dielectric layer 3, and the reflective layer 2. . The latter is a configuration in which the absorption layer 4 is a dielectric loss layer and the dielectric layer 3 is not provided separately. Each layer may be a single layer or multiple layers, and in the case of multiple layers, it is not necessary to be exactly the same layer. It is not limited to these, The laminated body of various aspects is included. In addition, these laminates are obtained by extracting the main layers and do not necessarily have to be arranged in this manner. For example, even if an adhesive layer, an adhesive layer, a support layer or a protective layer is inserted between the layers, the same effect is obtained. Is obtained. Further, by mixing an adhesive or a pressure-sensitive adhesive into the absorption layer 4 and the dielectric layer 3, the absorption layer 4 and the dielectric layer 3 can also be configured to serve as the adhesive layer and the pressure-sensitive adhesive layer.

  Furthermore, as an embodiment of the present invention, the electromagnetic wave absorber does not include the reflective layer 2 shown in FIGS. 2, 12, and 13, and the electromagnetic wave absorber that does not include the reflective layer 2 is an electromagnetic wave incident side. You may comprise so that the surface of an other side may be installed facing the object surface which has electromagnetic wave shielding performance. An object having electromagnetic wave shielding performance may have the same configuration as that of the reflective layer 2, for example, and may be realized by, for example, a metal plate. Such a configuration can obtain the same electromagnetic wave absorption characteristics as the electromagnetic wave absorber having the reflective layer 2.

  The above-described embodiment is merely an example of the present invention, and the configuration can be changed. For example, the pattern body 12 may be formed directly on the surface of the loss layer 7 such as the absorption layer 4 or the dielectric layer 3 and the plate-like substrate 11 may not be used. The loss layer 7 does not necessarily include both the absorption layer 4 and the dielectric layer 3. The loss layer 7 includes only one of them, for example, includes only the absorption layer 4 and does not include the dielectric layer 3. It may be a configuration. The loss layer 7 may be configured to include one or more other layers in addition to the absorption layer 4 and the dielectric layer 3. There may also be a configuration without the reflective layer 2. You may combine the structure of 2 or more forms of each above-mentioned embodiment.

  In the above-described embodiment, at least a part of the pattern piece is configured to have a rotational symmetry of 3, 4, or 6 times. However, the pattern piece has a rotational symmetry of 3 times or more. If it is a structure, the same effect can be achieved. In particular, a configuration having three, four, and six rotational symmetries is preferable because it is easy to arrange the patterns so as to satisfy both the rotational symmetry and the translational symmetry. In addition, the shape of the pattern pieces arranged in a rotationally symmetrical manner is not limited to a rectangular shape, an elliptical shape, a rhombus, and a parallelogram, as long as each inner angle is 180 ° or less and a polygonal shape excluding a regular polygonal shape is formed. Good. Further, it is only necessary that at least some of the pattern pieces have the rotational symmetry as described above. In a pattern layer having only a rectangular piece or an elliptical piece, the pattern area Sp is 0.55 or more, and in a pattern layer having a combination of a rectangular piece or an elliptical piece and a square piece or a circular piece, the pattern area It is preferable to select the dimension of each pattern piece so that Sp is 0.6 or more.

  Examples according to electromagnetic field simulation will be described below. The reflection characteristics when electromagnetic waves were irradiated vertically to the front surface of the absorber were evaluated by the TLM method (Transmission Line Matrix). FIG. 14 is a graph showing the absorption characteristics of the electromagnetic wave absorber 1 of Example 1. Table 1 shows the material constants of the electromagnetic wave absorber 1 of Example 1, and Table 2 shows the absorption characteristics of Example 1. The electromagnetic wave absorber 1 of Example 1 has a stacked configuration of FIG. 2 in which a pattern layer 5, an absorption layer 4, a dielectric layer 3, and a reflective layer 2 are stacked in this order from the electromagnetic wave incident side. The pattern body 12 has the configuration of FIG. 1 and FIG. 3, and the dimensions thereof are the first dimension L1 = 9.5 mm of the small square piece 13, the second dimension L2 = 24 mm of the large square piece, and the interval D = 4. 5 mm. As shown in FIG. 14 and Table 2, the electromagnetic wave absorber 1 of Example 1 has the frequency of the electromagnetic wave to be absorbed becomes 2.44 GHz and 5.21 GHz, and the absorption characteristics are bimodal.

  The material properties of the electromagnetic wave absorber 1 of Example 1 are shown in Table 1, and the values for the electromagnetic wave of 2.45 GHz are as follows. The pattern layer 5 is adhered to the absorbent layer 4 with an adhesive (first adhesive layer), and the base material 11 and the first adhesive layer (described as support / adhesive layer in Table 1) of the pattern layer 5 are The real part εr ′ = 3 and the imaginary part εr ″ = 0.01 of the dielectric constant, and the combined thickness of the base material 11 and the adhesive layer is 0.16 mm. The absorption layer 4 has a real part εr ′ = 12.86 and an imaginary part εr ″ = 1.29 of a relative dielectric constant, a real part μr ′ = 1.46 and an imaginary part μr ″ = 0 of a relative permeability. .43 and the thickness dimension is 0.5 mm. The dielectric layer 3 has a real part εr ′ = 4.22 and an imaginary part εr ″ = 0.12 of a relative dielectric constant, and has a thickness dimension of 2 mm. The dielectric layer 3 and the reflective layer 2 are bonded with an adhesive (second adhesive layer), and the second adhesive layer has a real part εr ′ = 3 and an imaginary part εr ″ = 0.01 of relative dielectric constant. Yes, the thickness dimension is 0.05 mm. The pattern body 12 and the reflective layer 2 of the pattern layer 5 are made of aluminum (Al) and have a conductivity σ = 3.54e7.

  FIG. 15 is a graph showing a comparison between the absorption characteristics of the electromagnetic wave absorber 1 of Example 1 and the absorption characteristics of the electromagnetic wave absorbers of Comparative Examples 1 and 2 having square pattern pieces of one type of dimensions. FIG. 16 is a front view showing the shapes of the pattern bodies of Comparative Example 1 and Comparative Example 2. Table 3 shows the absorption characteristics of the electromagnetic wave absorbers of Example 1 and Comparative Examples 1 and 2, and Table 4 shows the ratio of the pattern area to the specific pattern area of Example 1 and Comparative Examples 1 and 2. The electromagnetic wave absorbers of Comparative Examples 1 and 2 differ from the electromagnetic wave absorber 1 of Example 1 only in the pattern body 12. As shown in FIG. 16A, the pattern body of Comparative Example 1 has a configuration in which only the large square pieces 14 of Example 1 are arranged in a matrix at intervals D of Example 1. As shown in FIG. 16B, the pattern body 12 of the comparative example 2 has a configuration in which the small square pieces 13 and the rectangular pieces 15a and 15b are removed from the pattern body 12 of the first embodiment.

  As shown in FIG. 15 and Table 4, in Comparative Example 1 having only a square pattern piece 14 having a single dimension, absorption bands are provided in the 2.3 GHz band in which the pattern piece 14 resonates and the 7.1 GHz band in the higher order resonance. However, since the high-order resonance frequency appears in a frequency band about three times the basic resonance frequency, there is a limit to the control of the absorption band by the high-order resonance. In the case of Comparative Example 2, the resonance frequency is different from that of Comparative Example 1, but has the same problem. The electromagnetic wave absorber 1 of Example 1 according to the present invention has absorption peaks in two bands of 2.4 GHz band (2.4 GHz to less than 2.5 GHz) and 5.2 GHz band (5.2 GHz to less than 5.3 GHz). Existing.

  FIG. 17 is a graph showing a comparison between the absorption characteristics of the electromagnetic wave absorber 1 of Example 1 and the absorption characteristics of the electromagnetic wave absorbers of Comparative Examples 3 and 4 having square pattern pieces of two types of dimensions. FIG. 18 is a front view showing the shapes of the pattern bodies of Comparative Example 3 and Comparative Example 4. Table 5 shows the absorption characteristics of the electromagnetic wave absorbers of Example 1 and Comparative Examples 3 and 4, and Table 6 shows the ratio of the pattern area to the specific pattern area of Example 1 and Comparative Examples 3 and 4. The electromagnetic wave absorbers of Comparative Examples 3 and 4 differ from the electromagnetic wave absorber 1 of Example 1 only in the pattern body 12. As shown in FIG. 18A, the pattern body of Comparative Example 3 has a configuration in which the rectangular pieces 15a and 15b are removed from the pattern body 12 of Example 1. As shown in FIG. 18B, the pattern body 12 of Comparative Example 4 has a configuration in which the rectangular pieces 15 a and 15 b of the pattern body 12 of Example 1 are replaced with small square pieces 14.

  As shown in FIG. 17 and Table 5, in Comparative Examples 3 and 4 having large and small square pattern pieces, a 2.5 GHz band (2.5 GHz or more and less than 2.6 GHz) and a 5.7 GHz band ( 5.7 GHz or more and less than 5.8 GHz) shows a bimodal absorption characteristic, but there is a limit in arranging the pattern densely, and the peak absorption amount is the electromagnetic wave absorber 1 of Example 1 according to the present invention. Is not enough. According to the present invention, it is possible to obtain an electromagnetic wave absorber 1 having a bimodal absorption band with a large peak absorption.

  FIG. 19 is a graph showing a comparison between the absorption characteristics of the electromagnetic wave absorber 1 of Example 2 and the absorption characteristics of the electromagnetic wave absorber of Comparative Example 5 having a square pattern piece of one kind of size. FIG. 20 is a front view showing the shape of the pattern body of Comparative Example 5. Table 7 shows the absorption characteristics of the electromagnetic wave absorbers of Example 1 and Comparative Example 5. The electromagnetic wave absorber 1 of Example 2 has the same laminated structure as that of Example 1 in which the pattern layer 5, the absorption layer 4, the dielectric layer 3, and the reflective layer 2 are laminated in this order from the electromagnetic wave incident side. . The pattern body 12 has the configuration shown in FIGS. 1 and 3, and the dimensions are such that the first dimension L1 of the small square piece 13 is 22 mm, the second dimension L2 of the large square piece is 23.5 mm, and the interval D is 5 mm. is there.

  The material characteristics of the electromagnetic wave absorber 1 of Example 2 are the same as those of Example 1, and values for the electromagnetic wave of 2.45 GHz are as follows. The pattern layer 5 is adhered to the absorbent layer 4 with an adhesive (first adhesive layer), and the base material 11 and the first adhesive layer (described as support / adhesive layer in Table 1) of the pattern layer 5 are The real part εr ′ = 3 and the imaginary part εr ″ = 0.01 of the dielectric constant, and the combined thickness of the substrate 11 and the adhesive layer is 0.16. The absorption layer 4 has a real part εr ′ = 12.86 and an imaginary part εr ″ = 1.29 of a relative dielectric constant, a real part μr ′ = 1.46 and an imaginary part μr ″ = 0 of a relative permeability. .43 and the thickness dimension is 0.5 mm. The dielectric layer 3 has a real part εr ′ = 4.22 and an imaginary part εr ″ = 0.12 of a relative dielectric constant, and has a thickness dimension of 2 mm. The dielectric layer 3 and the reflective layer 2 are bonded with an adhesive (second adhesive layer), and the second adhesive layer has a real part εr ′ = 3 and an imaginary part εr ″ = 0.01 of relative dielectric constant. Yes, the thickness dimension is 0.05 mm. The pattern body 12 and the reflective layer 2 of the pattern layer 5 are made of aluminum (Al) and have a conductivity σ = 3.54e7.

  The electromagnetic wave absorber of Comparative Example 5 differs from the electromagnetic wave absorber 1 of Example 2 only in the pattern body 12. As shown in FIG. 17, the pattern body of Comparative Example 5 has a configuration in which only the large square pieces 14 of Example 2 are arranged in a matrix at intervals D of Example 2.

  As shown in FIG. 19 and Table 7, Comparative Example 5 having a single-dimensional square pattern has an absorption band in the 2.4 GHz band (2.4 GHz or more and less than 2.5 GHz) where the pattern resonates, but −15 dB The absorption bandwidth (the value obtained by reducing the lowest frequency from the highest frequency in the continuous frequency range in which a reflection loss of −15 dB or more is obtained) is 107 MHz, and −15 dB absorption of the electromagnetic wave absorber 1 of Example 2 according to the present invention. It does not reach the bandwidth of 119 MHz. As in the second embodiment, in the configuration having two types of pattern pieces having slightly different dimensions, it is possible to widen the frequency band that can be absorbed compared to the configuration having only one type of pattern pieces. According to the present invention, it is possible to obtain the electromagnetic wave absorber 1 having a wide absorption band and a wide band.

  FIG. 21 is a graph showing the absorption characteristics of the electromagnetic wave absorbers 1 of Examples 3 to 7. Table 8 shows the material constants of the electromagnetic wave absorber 1 of Examples 3 to 7, and Table 9 shows the absorption characteristics of Examples 3 to 7. Table 10 shows the ratio of the pattern area and the specific pattern area of Examples 3 to 7.

  The electromagnetic wave absorber 1 of Examples 3 to 7 has the laminated structure of FIG. 2 in which the pattern layer 5, the absorption layer 4, the dielectric layer 3, and the reflective layer 2 are laminated in this order from the electromagnetic wave incident side. The material properties of the electromagnetic wave absorbers 1 of Examples 3 to 7 are shown in Table 8, and values for electromagnetic waves of 2.45 GHz are as follows. The pattern layer 5 is adhered to the absorbent layer 4 with an adhesive (first adhesive layer), and the base material 11 and the first adhesive layer (described as support / adhesive layer in Table 1) of the pattern layer 5 are The real part εr ′ = 3 and the imaginary part εr ″ = 0.04 of the dielectric constant, and the combined thickness of the base material 11 and the adhesive layer is 0.16 mm. The absorbing layer 4 has a real part εr ′ = 23.23 of relative permittivity and an imaginary part εr ″ = 0.76, and a real part μr ′ = 1.20 and an imaginary part μr ″ = 0 of relative permeability. .47 and the thickness dimension is 0.5 mm. The dielectric layer 3 has a real part εr ′ = 4.49 of relative permittivity and an imaginary part εr ″ = 0.10, and has a thickness dimension of 2 mm. The pattern body 12 and the reflective layer 2 of the pattern layer 5 on which the reflective layer 2 is disposed on the back surface of the dielectric layer 3 are made of aluminum (Al) and have a conductivity σ = 3.54e7.

  The pattern body 12 of the third embodiment has the configuration shown in FIG. 5, and the dimensions thereof are the first dimension L1 = 21 mm of the first and second rectangular pieces 15a and 15b, and the first and second rectangular pieces 15a and 15b. The second dimension L2 = 9.5 mm and the interval D = 1 mm. As shown in FIG. 21 and Table 9, in the electromagnetic wave absorber 1 of Example 3, the frequency of the electromagnetic wave to be absorbed is 2.48 GHz and 5.28 GHz, and the absorption characteristics are bimodal.

  The pattern body 12 of the fourth embodiment has the configuration shown in FIG. 6, and the dimensions thereof are the first dimension L1 = 27.5 mm of the first and second elliptical pieces 15c and 15d, and the first and second elliptical pieces. The second dimension L2 of 15c and 15d is 10 mm, and the distance D is 1 mm. As shown in FIG. 21 and Table 9, in the electromagnetic wave absorber 1 of Example 4, the frequency of the electromagnetic wave to be absorbed is 2.45 GHz and 5.21 GHz, and the absorption characteristics are bimodal.

  The pattern body 12 of Example 5 has the configuration shown in FIG. 1, and the dimensions thereof are the first dimension L1 = 8 mm of the small square piece 13, the second dimension L2 = 21 mm of the large square piece 14, and the interval D = 2mm. is there. As shown in FIG. 21 and Table 9, in the electromagnetic wave absorber 1 of Example 5, the frequency of the electromagnetic wave to be absorbed is 2.49 GHz and 5.30 GHz, and the absorption characteristics are bimodal.

  The pattern body 12 of Example 6 has the configuration shown in FIG. 7, and the dimensions thereof are the first dimension L1 = 8.5 mm of the small square piece 13, the second dimension L2 = 22 mm of the large square piece 14, and the distance D =. The radius of curvature R is 3 mm. As shown in FIG. 21 and Table 9, in the electromagnetic wave absorber 1 of Example 6, the frequencies of electromagnetic waves to be absorbed are 2.47 GHz and 5.22 GHz, and the absorption characteristics are bimodal.

  The pattern body 12 of Example 7 has the configuration shown in FIG. 8, and the dimensions thereof are the first dimension L1 = 9 mm of the small circular piece 13a and the first and second elliptical pieces 15c, 15d, and the large circular piece 14a. The second dimension L2 of the first and second elliptical pieces 15c and 15d is 26 mm and the distance D is 2 mm. As shown in FIG. 21 and Table 9, in the electromagnetic wave absorber 1 of Example 7, the frequencies of electromagnetic waves to be absorbed are 2.46 GHz and 5.21 GHz, and the absorption characteristics are bimodal.

  Therefore, the electromagnetic wave absorbers 1 of Examples 3 to 7 according to the present invention have two bands of 2.4 GHz band (2.4 GHz or more and less than 2.5 GHz) and 5.2 GHz band (5.2 GHz or more and 5.3 GHz or less). It can be seen that there is an absorption peak, and the absorption characteristics are bimodal.

  Hereinafter, examples according to the free space method will be described. In the free space method, an electromagnetic wave is transmitted from a transmitting antenna, an electromagnetic wave absorber that is a measurement sample placed in free space is irradiated with a plane wave, and the reflected wave is received by the receiving antenna to obtain the reflection coefficient of the absorber. Is the method. This time, measurement was performed for both TE wave and TM wave with an incident angle of 10 °. The measuring instrument used was a network analyzer (trade name HP8720ES manufactured by Agilent Technologies), and the antenna was a double rigid antenna. The size of each side of the rectangle of the measurement sample that is the electromagnetic wave absorber 1 is 500 × 500 (mm).

  The absorber structure is the structure of the pattern layer 5, the loss layer 7, and the reflective layer 2 from the surface side, and each layer is joined via the adhesion layer. The pattern layer is composed of a PET film substrate having a thickness of 100 μm and a conductive pattern. The conductive pattern is formed by printing a conductive ink made of silver paste. The loss layer 7 is composed of an absorption layer 4 and a dielectric layer 3. The absorption layer 4 is made of PVC, which is a magnetic loss material, and graphite, which is a magnetic loss material. The dielectric layer 3 is made of PVC, and the absorption layer 4. And the dielectric layer 3 are integrated by heat fusion. The composition of the absorption layer 4 is based on PVC (Kaneka Co., Ltd., KS1700) 100 (phr), ferrite (LD-M manufactured by JFE Ferrite Co., Ltd.) 235 (phr), graphite (Nippon Graphite Co., Ltd. Blue P 65 (phr)) Are added with plasticizer, dispersant, calcium carbonate, etc. The material constants of the absorption layer 4 and the dielectric layer 3 measured by the coaxial tube method are shown in Table 11, but the values for electromagnetic waves of 2.45 GHz are described. The absorption layer 4 has a real part εr ′ = 23.31 and an imaginary part εr ″ = 0.93 of the relative permittivity, a real part μr ′ = 1.29 of the relative permeability, and The imaginary part μr ″ = 0.6 and the thickness dimension is 0.5 mm. The dielectric layer 3 has the real part εr ′ = 4.56 and the imaginary part εr ″ = 0.09 of the relative permittivity. The thickness is 2 mm, and the reflective layer 2 is a 25 μm PET film. This is a sheet in which aluminum is vapor-deposited on a base material and a support layer made of 75 μm PVC is bonded to the aluminum vapor-deposited surface side with an adhesive, the conductive ink side of the pattern layer 5 and the absorption layer 4 side of the loss layer 7, loss The dielectric layer 3 side of the layer 7 and the PET base material side of the reflective layer 2 are bonded to each other using a 30 μm double-sided adhesive tape (manufactured by Teraoka Seisakusho).

  22 and Table 12 are graphs and tables showing absorption characteristics for TE waves with an incident angle of 10 ° in Examples 8 and 9 and Comparative Example 6, and FIG. 23 and Table 13 are Examples 8 and 9 and Comparative Example. 6 is a graph and a table showing absorption characteristics for a TM wave with an incident angle of 10 ° of 6. FIG.

  22 and 23, the reflection characteristic | ΔS21 | indicating the absorption characteristic is a reflection characteristic of the absorber when the reflection characteristic when the metal plate is installed is a reference (0 dB), and the reflection characteristic is transmitted from the transmitting antenna. The ratio of the power of the electromagnetic wave received by the receiving antenna to the power of the electromagnetic wave is expressed in decibels.

  The pattern shape of the eighth embodiment is the same as that of the fifth embodiment. The pattern body 12 has the configuration shown in FIG. L2 = 21 mm and the interval D = 2 mm. In the electromagnetic wave absorber 1 of Example 8, as shown in FIGS. 22 and 23 and Tables 12 and 13, the frequencies of electromagnetic waves to be absorbed are 2.49 GHz and 5.29 GHz, and the absorption characteristics are bimodal. .

  The pattern shape of the ninth embodiment is the same as that of the sixth embodiment, and the pattern body 12 has the configuration of FIG. 7. The dimensions of the pattern body 12 are the first dimension L1 = 8.5 mm of the small square piece 13, and Two dimensions L2 = 22 mm, a distance D = 2 mm, and a radius of curvature R is 3 mm. In the electromagnetic wave absorber 1 of Example 9, as shown in FIGS. 22 and 23 and Tables 12 and 13, the frequencies of electromagnetic waves to be absorbed are 2.53 GHz and 5.21 GHz, and the absorption characteristics are bimodal. .

  The pattern layer of Comparative Example 6 is a conductive pattern formed by aluminum deposition, and the pattern shape is a combination of a square pattern with R with R at the corner and a cross-shaped pattern with R with R at the corner. It has the structure shown in FIG. The dimensions are a cross length a2x, a2y = 17.5 mm, a cross width a1x, a1y = 1.5 mm, a square dimension = 20.5 mm, a distance D = 1.5 mm, a cross curvature radius R is 7.5 mm, The square cross curvature radius R is 7 mm. As shown in FIGS. 22 and 23 and Tables 12 and 13, the electromagnetic wave absorber 1 of Comparative Example 6 has a single-peak absorption characteristic when the frequency of the electromagnetic wave to be absorbed is only 2.45 GHz.

  Therefore, the electromagnetic wave absorber 1 of Examples 8 and 9 according to the present invention has two bands of 2.4 GHz band (2.4 GHz or more and less than 2.5 GHz) and 5.2 GHz band (5.2 GHz or more and 5.3 GHz or less). It can be seen that there is an absorption peak, and the absorption characteristics are bimodal.

It is a front view which shows a part of electromagnetic wave absorber 1 of one Embodiment of this invention. 1 is a cross-sectional view showing a part of an electromagnetic wave absorber 1. 3 is an enlarged front view showing one pattern group 17 in the pattern body 12. FIG. It is a front view which shows a part of electromagnetic wave absorber 1A of the other form of implementation of this invention. It is a front view which shows a part of electromagnetic wave absorber 1D of further another form of implementation of this invention. It is a front view which shows a part of electromagnetic wave absorber 1E of the further another form of implementation of this invention. It is a front view which shows a part of electromagnetic wave absorber 1F of further another form of implementation of this invention. It is a front view which shows a part of electromagnetic wave absorber 1G of the further another form of implementation of this invention. It is a front view which shows a part of electromagnetic wave absorber 1H of the further another form of implementation of this invention. It is a front view which shows a part of electromagnetic wave absorber 1J of further another form of implementation of this invention. It is a front view which shows a part of electromagnetic wave absorber 1K of further another form of implementation of this invention. It is sectional drawing which shows a part of electromagnetic wave absorber 1B of the further another form of implementation of this invention. It is sectional drawing which shows a part of electromagnetic wave absorber 1C of further another form of implementation of this invention. 3 is a graph showing the absorption characteristics of the electromagnetic wave absorber 1 of Example 1. It is a graph which compares and shows the absorption characteristic of the electromagnetic wave absorber 1 of Example 1, and the electromagnetic wave absorber of the comparative examples 1 and 2 which have a square pattern piece of one kind of dimension. It is a front view which shows the shape of the pattern body of the comparative example 1 and the comparative example 2. FIG. It is a graph which compares and shows the absorption characteristic of the electromagnetic wave absorber 1 of Example 1, and the electromagnetic wave absorber of the comparative examples 3 and 4 which have a square pattern piece of two types of dimensions. It is a front view which shows the shape of the pattern body of the comparative example 3 and the comparative example 4. FIG. It is a graph which compares and shows the absorption characteristic of the electromagnetic wave absorber 1 of Example 2, and the absorption characteristic of the electromagnetic wave absorber of the comparative example 5 which has a square pattern piece of one kind of dimension. It is a front view which shows the shape of the pattern body of the comparative example 5.

It is a graph which shows the absorption characteristic of the electromagnetic wave absorber 1 of Examples 3-7. It is a graph which shows the absorption characteristic with respect to the TE wave of the incident angle 10- of Example 8, 9 and the comparative example 6. FIG. It is a graph which shows the absorption characteristic with respect to TM wave of the incident angle 10- of Example 8, 9 and the comparative example 6. FIG. 10 is a plan view showing a conductive pattern of Comparative Example 6. FIG.

Explanation of symbols

1, 1A, 1B, 1C, 1E, 1F, 1G, 1H, 1J, 1K Electromagnetic wave absorber 2 Reflective layer 3 Dielectric layer 4 Absorbing layer 5 Pattern layer 11 Plate substrate 11 Pattern body 13 Small square piece 13a Small circle Piece 14 Large square piece 14a Large square piece 15a, 15b Rectangular piece 15c, 15d Elliptical piece 15e Rhombus piece 17 Pattern group 21 Square piece 22a, 22b Hexagon piece

Claims (21)

A pattern layer on which a conductive pattern body made of a conductive material is formed, the conductive pattern bodies being provided apart from each other, each interior angle being 180 ° or less, and a polygon other than a regular polygon Alternatively, a pattern layer that is formed in an ellipse and includes part of pattern pieces arranged in different directions and has translational symmetry,
An electromagnetic wave absorber comprising a structure in which at least one loss layer having a portion made of a material that is at least one of a magnetic loss material and a dielectric loss material is laminated.   The electromagnetic wave absorber according to claim 1, wherein the pattern pieces are arranged so as to have a rotational symmetry of three or more times.   The electromagnetic wave absorber according to claim 2, wherein the pattern pieces are arranged so as to have at least one of three, four, or six rotational symmetry.   The pattern layer has an area ratio in which the area of the region where the conductive pattern body is formed is 0.55 or more when the area of the entire pattern layer region is 1. Electromagnetic wave absorber as described in any one of these.   The electromagnetic wave absorber according to any one of claims 1 to 4, wherein the pattern piece and a pattern piece formed in a regular polygon or a circle are arranged in combination. The pattern piece formed into a polygon excluding a regular polygon is formed in a rectangle whose length dimension of each side is not less than the first dimension and not more than the second dimension,
The conductive pattern body further includes a small square pattern piece whose one side length is a first dimension, and a large square pattern piece whose one side length is a second dimension larger than the first dimension. The electromagnetic wave absorber according to claim 5.   The electromagnetic wave absorber according to claim 6, wherein the rectangular pattern piece includes two short sides having a first dimension and two long sides having a second dimension.   The small square pattern piece and the large square pattern piece are arranged such that the diagonal line of the small square pattern piece and the diagonal line of the large square pattern piece are arranged on the same straight line. The rectangular pattern pieces are arranged such that the short side faces one side of the small square pattern piece and the long side faces one side of the large square pattern piece, and these four pattern pieces are grouped into one group. The electromagnetic wave absorber according to claim 6 or 7, wherein pattern groups to be arranged are arranged.   9. The corner portion of the small square pattern piece and at least one corner portion of the corner portion of the large square pattern piece are formed in a curved shape. The electromagnetic wave absorber as described in one.   The electromagnetic wave absorber according to any one of claims 6 to 9, wherein at least one or more corner portions of the rectangular pattern pieces are formed in a curved shape.   11. The pattern layer has an area ratio in which an area of a region where the conductive pattern body is formed is 0.6 or more when an area of the entire pattern layer region is 1. Electromagnetic wave absorber as described in any one of these.   The electromagnetic wave absorber according to claim 1, wherein the loss layer includes a layer made of at least a magnetic loss material. The loss layer is
A layer of at least a magnetic loss material;
It has a layer which consists of a dielectric loss material at least, The electromagnetic wave absorber as described in any one of Claims 1-12 characterized by the above-mentioned.   The electromagnetic wave absorber according to any one of claims 1 to 13, which absorbs two or more electromagnetic waves having different frequencies.   The pattern layer includes a plurality of pattern pieces, and the basic resonance frequency and the higher-order resonance frequency of the first pattern piece are different from the basic resonance frequency of at least one of the other pattern pieces. The electromagnetic wave absorber according to any one of claims 1 to 14.   The electromagnetic wave absorber according to any one of claims 1 to 15, wherein the electromagnetic wave absorber absorbs electromagnetic waves in any part of a band from 300 MHz to 30 GHz. An electromagnetic wave absorber for absorbing 2.4 GHz band electromagnetic waves,
The total thickness dimension is 5 mm or less, The electromagnetic wave absorber as described in any one of Claims 1-16 characterized by the above-mentioned.   The electromagnetic wave absorber according to claim 1, which has an electromagnetic wave shielding property for shielding electromagnetic waves.   The electromagnetic wave absorber according to any one of claims 1 to 18, wherein the electromagnetic wave absorber has flame retardancy, quasi-incombustibility, or incombustibility.   A building material comprising the electromagnetic wave absorber according to any one of claims 1 to 19.   The electromagnetic wave absorption method by using the electromagnetic wave absorber as described in any one of Claims 1-20.

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