Electromagnetic scattering body

Abstract

To provide an electromagnetic wave scatterer capable of reflecting electromagnetic waves in a wide range of directions.SOLUTION: The present invention is a sheet-shaped electromagnetic wave scatterer 11, and comprises a conductive layer 16 containing reflective elements 12 that reflect electromagnetic waves and a base material layer 13 supporting the conductive layer 16, and the maximum height undulation of the cross-sectional curve of the reflective element 12 at any cross-section along the thickness direction of the electromagnetic wave scatterer 11 is 0.5 mm or more.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electromagnetic wave scatterer. [Background technology]

[0002] Mobile phones and wireless communications use electromagnetic waves in the frequency band of about 3 GHz to 300 GHz, known as centimeter waves or millimeter waves. Such short-wavelength electromagnetic waves tend to travel in a straight line, and if there is an obstacle between the transmitting antenna and the receiving antenna, the electromagnetic waves have difficulty circumventing the obstacle and reaching the receiving antenna. For this reason, reflectors that reflect electromagnetic waves in a desired direction are provided on the surfaces of buildings, such as the walls, floors, ceilings, and pillars of buildings (hereinafter referred to as "walls, etc."). For example, Patent Document 1 proposes a reflectarray that reflects electromagnetic waves in a specified direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-045378 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the reflectarray described in Patent Document 1, the reflection of electromagnetic waves is limited to one direction, and it is not possible to reflect the waves in a wide range of directions (beam width).

[0005] An object of the present invention is to provide an electromagnetic wave scatterer capable of reflecting electromagnetic waves in a wide range of directions. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention includes the subject matter described in the following paragraphs.

[0007] Item 1: A sheet-like electromagnetic wave scatterer comprising a conductive layer including a reflecting element that reflects electromagnetic waves, and a base layer that supports the conductive layer, An electromagnetic wave scatterer, wherein the maximum height waviness of the cross-sectional curve of the reflective element in any cross section along the thickness direction of the electromagnetic wave scatterer is 0.5 mm or more.

[0008] Item 2: The electromagnetic wave scatterer according to item 1, having a thickness of 0.05 mm or more and 10 mm or less.

[0009] Term 3: If the wavelength of the electromagnetic wave reflected by the electromagnetic wave scatterer is λ, then Radar cross section (RCS) is 200λ 2 That's all. 3. The electromagnetic wave scatterer according to claim 1 or 2, wherein the 3 dB beam width, which is 3 dB less than the maximum gain, is 1 degree or more.

[0010] Item 4: The reflective element is formed in plurality on the base layer; If the wavelength of the electromagnetic wave reflected by the electromagnetic wave scatterer is λ, then From a plan view, The area of ​​at least one of the reflective elements is λ 2 More than 400λ 2 It is set to: An electromagnetic wave scatterer according to any one of items 1 to 3, wherein the shortest distance between any points on the edges of adjacent reflecting elements is set to 1.1 λ or more. Effect of the Invention

[0011] According to the present invention, it is possible to provide an electromagnetic wave scatterer capable of reflecting electromagnetic waves in a wide range of directions. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1A is a cross-sectional view showing a schematic configuration of an electromagnetic wave scatterer according to an embodiment of the present invention, and FIG. 1B is an enlarged view of a portion A in FIG. [Diagram 2] 2 is a plan view showing a schematic overall configuration of the electromagnetic wave scatterer shown in FIG. [Diagram 3] FIG. 2 is an explanatory diagram of a beam width. [Figure 4] 13 is a modified example of the arrangement of the conductive layer. [Diagram 5] 13 is a diagram showing a modified example of the shape pattern of the conductor of the reflective element. [Figure 6] 6 is a plan view showing an example of an arrangement of a plurality of reflective elements shown in FIG. 5(A). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] (Overall configuration of electromagnetic wave scatterer 11) An embodiment of the present invention will be described with reference to the drawings. As shown in Fig. 1(A), an electromagnetic wave scatterer 11 of the present invention includes a conductive layer 16 including a reflecting element 12 that reflects electromagnetic waves, and a base layer 13 that supports the conductive layer 16. In this embodiment, the electromagnetic wave scatterer 11 further includes a protective layer 15 that protects the conductive layer 16, and an adhesive layer 14 that bonds the conductive layer 16 and the protective layer 15, and is laminated in the order of the base layer 13, the conductive layer 16, the adhesive layer 14, and the protective layer 15. Details of each layer will be described later. In Fig. 2(A), the adhesive layer 14 and the protective layer 15 are omitted from the illustration of a part of the electromagnetic wave scatterer 11.

[0014] In the following description, the direction in which the layers are stacked is defined as the up-down direction, and the up-down direction of the electromagnetic wave scatterer 11 corresponds to the up-down direction in Fig. 1. Furthermore, the vertical and horizontal directions are defined based on Fig. 2 and Fig. 5. The up-down direction and the vertical and horizontal directions are used for the purpose of explanation, and do not define the up-down direction and the vertical and horizontal directions when the electromagnetic wave scatterer 11 is used, such as when it is attached to a building or the like. Furthermore, the drawings are not shown to actual scale.

[0015] When the electromagnetic wave scatterer 11 is attached flat to a wall or the like, it reflects electromagnetic waves having an incident frequency of 3 GHz or more and 5 GHz or less, 25 GHz or more and 30 GHz or less, or 100 GHz or more and 300 GHz or less.

[0016] The electromagnetic wave scatterer 11 is in the form of a sheet. In this specification, the term "sheet" refers to a shape in which the thickness of the object is 10% or less of the maximum length between the outer edges in a planar view. When the shape in a planar view is rectangular, the "maximum length between the outer edges in a planar view" refers to the length of the diagonal. When the shape in a planar view is circular, the "maximum length between the outer edges in a planar view" refers to the length of the diameter. In this specification, membranes, foils, films, etc. are also included in the term "sheet."

[0017] The electromagnetic wave scatterer 11 according to this embodiment is quadrilateral (including square and rectangle) in plan view as shown in Fig. 2. The length L10 of one side of the electromagnetic wave scatterer 11 is, for example, preferably 20 cm or more, more preferably 100 cm or more, and even more preferably 200 cm or more. On the other hand, the upper limit of the length L10 of one side of the electromagnetic wave scatterer 11 is not particularly limited, but is, for example, 400 cm or less. When the length L10 of one side is 20 cm or more, electromagnetic waves are easily reflected with sufficient intensity.

[0018] The thickness L1 of the electromagnetic wave scatterer 11 is preferably 0.05 mm or more and 10 mm or less, and more preferably 0.08 mm or more and 1.00 mm or less. When the thickness L1 of the electromagnetic wave scatterer 11 is 0.05 mm or more, the electromagnetic wave scatterer 11 can maintain its strength while having flexibility. When the thickness L1 of the electromagnetic wave scatterer 11 is 10 mm or less, the electromagnetic wave scatterer 11 can be made thin and is less likely to bend when curved, and as a result, stress concentration is less likely to occur in the reflection element 12. The term "bend" used here means bending accompanied by plastic deformation in any layer of the electromagnetic wave scatterer 11.

[0019] (Conductive layer 16) The reflective elements 12 of the conductive layer 16 of the electromagnetic wave scatterer 11 are conductors made of thin films formed in a square shape in a plan view on the upper surface of the base layer 13 as shown in Fig. 2. In the example of Fig. 2, the reflective elements 12 are formed slightly smaller than the base layer 13, but they may be the same size. The conductor of the reflective elements 12 is preferably made of silver, for example.

[0020] Furthermore, the thickness L3 of the conductive layer 16, i.e., the thickness (film thickness) L3 of the conductor of the reflecting element 12, is preferably a thickness that has visible light transmittance. The thickness L3 of the reflecting element 12 is preferably 0.05 μm or more and 10 μm or less. From the viewpoint of ensuring appropriate electromagnetic wave intensity, the thickness L3 is preferably 5 nm or more.

[0021] A plurality of reflective elements 12 may be formed on the upper surface of one base layer 13. For example, in the example of Fig. 4, the conductive layer 16 includes four reflective elements 12, and a total of four reflective elements 12 having a square shape in plan view are arranged on the upper surface of one base layer 13, two vertically and two horizontally.

[0022] In this way, when the conductive layer 16 includes a plurality of reflective elements 12, the area of ​​at least one reflective element 12 in a plan view is λ 2 More than 400λ 2 (lambda × lambda or more, 400 × lambda × lambda or less). The area of ​​all reflective elements is set to lambda 2 More than 400λ 2 or less. The shortest distance L21 between any points on the edge of adjacent reflective elements 12 is set to 1.1λ or more and 3λ or less, and more preferably, 1.2λ or more and 2.7λ or less. In the example of Fig. 4, the shortest distance L21 is the minimum value of the distance between any points on the conductors of adjacent reflective elements 12.

[0023] (Maximum swell height Wz) Assuming that the protective layer 15 side of the laminated electromagnetic wave scatterer 11 is the upper side and the base layer 13 side is the lower side, as shown in FIG. 1(B), in any cross section along the thickness direction of the electromagnetic wave scatterer 11, the upper edge of the cross section of the reflective element 12 of the conductive layer 16 is a curve with vertical unevenness. The maximum waviness height Wz of this curve (cross-sectional curve) is set to 0.5 mm or more. The maximum waviness height Wz is specified in JIS B0601:2013. In this embodiment, since the reflective element 12 is a thin-film conductor, the upper edge of the cross section of the conductor is set to be the cross-sectional curve.

[0024] 1(B), the upper edge of the cross section of the conductive layer 16 of the reflective element 12 is curved, and the thickness L3 of the reflective element 12 is not uniform. However, the upper edge of the cross section of the base material layer 13 may be formed to have an uneven curve, and may be formed on the upper surface of the base material layer 13 of the reflective element 12 having a uniform thickness L3. In this case, the upper edge of the cross section of the reflective element 12 is curved corresponding to the curve of the upper edge of the base material layer 13.

[0025] (Reflection performance of electromagnetic wave scatterer 11) The electromagnetic wave scatterer 11 has a radar cross section (RCS) of 200λ 2 (200×λ×λ) mm 2 (square millimeters) or more. Radar cross section is a measure of the ability of a material to reflect electromagnetic waves in the direction of an antenna when irradiated by a radar, and is a function of the geometric cross section, reflectivity, and directivity. Radar cross section is expressed as the area of ​​an isotropic reflector (the cross section of a sphere made of a perfect conductor) that can reflect electromagnetic waves of equal strength to the reflected wave.

[0026] The electromagnetic wave scatterer 11 has a 3 dB beam width (also simply called "beam width") of 1 degree or more, which is 3 dB less than the maximum gain of the reflected wave when the electromagnetic wave is reflected. The beam width refers to the angle between two directions B including direction A when direction A in which the reflection intensity of the electromagnetic wave is maximum (maximum gain) and two directions B in which the reflection intensity of the electromagnetic wave is 3 dB lower than the maximum gain are on the same plane. In this case, the magnitude of the beam width is expressed as an angle. The direction in which the maximum gain occurs (reflection angle) may coincide with the direction of specular reflection, but it does not have to coincide with the direction of specular reflection.

[0027] Figure 3 is an explanatory diagram of beam width. The horizontal axis shows the reflection direction of the electromagnetic wave in degrees, and the direction in which the reflection intensity of the reflected wave has the maximum gain is set to an angle of 0 degrees. The vertical axis shows the reflection intensity of the electromagnetic wave. In the example of Figure 3, the angle in the direction in which the maximum gain is 11.47 dB is 0 degrees. The angles at which the reflection intensity is greater than 8.47 (3 dB less than 11.47 dB) are between -0.9 degrees and 0.89 degrees, and the beam width is 1.79 degrees.

[0028] By setting the maximum waviness height Wz of the cross-sectional curve of the reflecting element 12 of the conductive layer 16 to 0.5 mm or more, the electromagnetic wave scatterer 11 can scatter the electromagnetic wave with a wide beam width. Furthermore, a plurality of reflecting elements 12 may be formed on one electromagnetic wave scatterer 11, in which case the electromagnetic wave can be scattered over an even wider range. Furthermore, it is known that the beam width of a conventional electromagnetic wave scatterer becomes smaller as the overall size increases, and the electromagnetic wave cannot be received if the receiving antenna moves frequently. However, according to the electromagnetic wave scatterer 11 of this embodiment, the beam width is larger than that of a conventional electromagnetic wave scatterer of the same size, and the electromagnetic wave can be scattered over a wider range.

[0029] (Evaluation test) Examples 1 to 3 were prepared as the electromagnetic wave scatterer 11, and an evaluation test was performed on the electromagnetic wave reflection intensity for Examples 1 to 3 and Comparative Examples 1 and 2. However, the electromagnetic wave scatterer 11 of the present invention is not limited to Examples 1 to 3. Table 1 shows the configurations and evaluation results of Examples 1 to 3 and Comparative Examples 1 and 2.

[0030] (Explanation of Examples and Comparative Examples) Example 1 The electromagnetic wave scatterer 11 produced as Example 1 has the following configuration. Thickness of the electromagnetic wave scatterer 11: 3 mm Maximum waviness height Wz: 0.5mm Number of reflective elements 12: 1 Planar area of ​​the reflective element 12: 40,000 mm 2 (square millimeters) Planar area of ​​the electromagnetic wave scatterer 11: 40,000 mm 2 (square millimeters) Minimum distance L21 between reflective elements 12: Not specified since the number of reflective elements 12 is one (shown as "-" in Table 1). Electromagnetic wave frequency: 30GHz Wavelength: 10mm

[0031] Example 2 The electromagnetic wave scatterer 11 produced as Example 2 has the following configuration. Example 2 differs from Example 1 in maximum waviness height Wz. Thickness of the electromagnetic wave scatterer 11: 3 mm Maximum waviness height Wz: 20mm Number of reflective elements 12: 1 Planar area of ​​the reflective element 12: 40,000 mm 2 (square millimeters) Planar area of ​​the electromagnetic wave scatterer 11: 40,000 mm 2 (square millimeters) Minimum distance L21 between reflective elements 12: Not specified since the number of reflective elements 12 is one (shown as "-" in Table 1). Electromagnetic wave frequency: 30GHz Wavelength: 10mm

[0032] Example 3 The electromagnetic wave scatterer 11 created as Example 3 has the following configuration. Example 3 differs from Example 1 in the number of multiple reflective elements 12 and the area of ​​the electromagnetic wave scatterer 11. In Example 3, a total of four square reflective elements 12 of the same shape are arranged in two rows and two columns. Thickness of the electromagnetic wave scatterer 11: 3 mm Maximum waviness height Wz: 0.5mm Number of reflective elements 12: 4 Planar area of ​​each reflective element 12: 40,000 mm 2 (square millimeters) (The length of one side of each reflective element 12, L20: 200 mm) Planar area of ​​the electromagnetic wave scatterer 11: 168,921 mm 2 (square millimeters) Shortest distance between reflective elements 12 L21: 11 mm Electromagnetic wave frequency: 30GHz Wavelength: 10mm

[0033] Comparative Example 1 The electromagnetic wave scatterer 11 produced as Comparative Example 1 has the following configuration: Comparative Example 1 differs from Example 1 in maximum waviness height Wz. Thickness of the electromagnetic wave scatterer 11: 3 mm Maximum waviness height Wz: 0mm Number of reflective elements 12: 1 Planar area of ​​the reflective element 12: 40,000 mm 2 (square millimeters) Planar area of ​​the electromagnetic wave scatterer 11: 40,000 mm 2 (square millimeters) Minimum distance L21 between reflective elements 12: Not specified since the number of reflective elements 12 is one (shown as "-" in Table 1). Electromagnetic wave frequency: 30GHz Wavelength: 10mm

[0034] Comparative Example 2 The electromagnetic wave scatterer 11 created as Comparative Example 2 has the following configuration. Comparative Example 2 differs from Example 1 in the maximum waviness height Wz and the number and area of ​​the reflective elements 12. In Comparative Example 2, a total of 49 square reflective elements 12 of the same shape are arranged in 7 rows and 7 columns. Thickness of the electromagnetic wave scatterer 11: 3 mm Maximum waviness height Wz: 0mm Number of reflective elements 12: 49 Planar area of ​​each reflective element 12: 400 mm 2 (square millimeters) Planar area of ​​the electromagnetic wave scatterer 11: 40,000 mm 2 (square millimeters) Shortest distance between reflective elements 12 L21: 10 mm Electromagnetic wave frequency: 30GHz Wavelength: 10mm

[0035] [Table 1]

[0036] (Common configuration among Examples 1 to 3 and Comparative Examples 1 and 2) Planar shape of the electromagnetic wave scatterer 11: Square Length of one side of the electromagnetic wave scatterer 11 L10: 200 mm

[0037] Material of the base layer 13: Synthetic resin material sheet made of PET (Toray Industries, Lumirror 50T60) Thickness L2 of the base layer 13: 0.13 mm

[0038] Planar shape of the reflective element 12 of the conductive layer 16: Square Material of the reflective element 12 of the conductive layer 16: Metal thin film made of copper (Cu) Thickness (film thickness) L3 of the conductive layer 16 of the reflecting element 12: 7 μm

[0039] Material of adhesive layer 14: rubber-based adhesive (a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer, a dropping funnel and a stirrer was charged with 100 parts by weight of a rubber-based polymer (a mixture of 50% by weight of styrene-(ethylene-propylene)-styrene type block copolymer and 50% by weight of styrene-(ethylene-propylene) type block copolymer, styrene content 15%, weight average molecular weight 130,000), 40 parts by weight of a synthetic resin (Mitsui Chemicals, Inc., FMR-0150), 20 parts by weight of a softener (JX Nippon Oil & Energy Corporation, LV-100), 0.5 parts by weight of an antioxidant (ADEKA Corporation, Adekastab AO-330) and 150 parts by weight of toluene, and stirred at 40° C. for 5 hours). Thickness L4 of adhesive layer 14: 0.05 mm

[0040] Material of protective layer 15: Synthetic resin sheet made of PET (Toray Industries, Lumirror 50T60) Thickness L5 of protective layer 15: 0.13 mm

[0041] (Measurement of reflection intensity (maximum gain) and calculation of beam width) The reflected wave intensity of the measurement objects, Examples 1 to 3 and Comparative Examples 1 and 2 (collectively referred to as "samples"), was measured using a cylindrical near-field far-field conversion radar cross section (RCS) measurement system (model number RCS03) provided by KEYCOM Corporation. In this system, two probe antennas (hereinafter also referred to as "transmitting antenna" and "receiving antenna") constituting a transmitter and a receiver are provided vertically on the same support base. The sample is attached to a rotating base. The distance between the transmitting antenna and the receiving antenna and the sample is set to 2000 mm. The direction in which the transmitting antenna transmits electromagnetic waves to the sample is the same as the direction in which the receiving antenna receives reflected waves from the sample. The transmitting antenna and the receiving antenna are connected to a vector network analyzer, a computer, etc.

[0042] The direction of the sample relative to the probe antenna is adjusted by the rotating table so that the incident angle is a specified angle. The specified angles of incidence are from 0 degrees to 60 degrees in increments of 0.1 degrees. At each incident angle, an electromagnetic wave with a frequency of 30 GHz and an intensity of 0.1 mW is output from the transmitter, and the reflection intensity of the reflected wave reflected by the sample is measured by the receiver. In other words, the receiver measures the reflection intensity of the reflected wave with successively different reflection angles. The maximum value of the measured reflection intensity is the maximum gain. The reflection angle of the reflected wave with the maximum gain is set to 0 degrees, and the angle between the two directions where the reflection intensity of the electromagnetic wave is 3 dB lower than the maximum gain is set to the beam width. In calculating the beam width, the direction of the reflected wave with the maximum gain and the two directions where the reflection intensity is 3 dB lower than the maximum gain are assumed to be on the same plane.

[0043] (evaluation) We evaluated whether electromagnetic waves of sufficient strength could reach the receiving antenna. The radar cross section (RCS) was 200λ. 2 (mm 2 ) or more (in this evaluation test, the radar cross section is 20,000 mm 2The cases where all of the following are met are evaluated as "○", and the case where any one of them is not met is evaluated as "×".

[0044] In Example 1, the maximum gain is 11.9 dB, the beam width is 1 degree, and the radar cross section is 1,765,600 mm 2 Therefore, it was evaluated as "○". In Example 2, the maximum gain was -3.2 dB, the beam width was 68.6 degrees, and the radar cross section was 86,905 mm 2 Therefore, it was evaluated as "○". In Example 3, the maximum gain was 23.6 dB, the beam width was 1.72 degrees, and the radar cross section was 4,038,800 mm 2 Therefore, it was rated as "○". On the other hand, the beam width of Comparative Example 1 was 0.7 degrees, and the beam width of Comparative Example 2 was 0.9 degrees, so the electromagnetic waves did not reach the receiving antenna with sufficient strength, and they were rated as "×".

[0045] (Modification of the electromagnetic wave scatterer 11) The shape of the electromagnetic wave scatterer 11 is not limited to a rectangle, and may be a geometric shape such as a triangle, a pentagon, a hexagon, a circle, an ellipse, or a non-geometric shape. In the electromagnetic wave scatterer 11, the maximum dimension of the distance between the edges is preferably 20 cm or more and 400 cm or less. The "maximum dimension of the distance between the edges" refers to the diagonal dimension when the electromagnetic wave scatterer 11 is rectangular, refers to the diameter dimension when the electromagnetic wave scatterer 11 is circular, and refers to the length of the major axis when the electromagnetic wave scatterer 11 is elliptical.

[0046] (Modifications of the Conductive Layer 16) The conductor of the conductive layer 16 may be made of a metal, metal compound, or alloy having free electrons, and is not limited to silver, but may be, for example, gold, copper, platinum, aluminum, titanium, silicone, indium tin oxide, and alloys (for example, alloys containing nickel, chromium, and molybdenum), etc. Examples of alloys containing nickel, chromium, and molybdenum include various grades of Hastelloy B-2, B-3, C-4, C-2000, C-22, C-276, G-30, N, W, X, etc.

[0047] In the embodiment of Figure 2, the shapes (patterns) of the conductors of each reflective element 12 in the conductive layer 16 are all the same shape, size, and material, but they may include a number of different shapes and may be different sizes and materials.

[0048] The shape (pattern) of the conductive layer 16 when viewed from the plane of the reflective element 12 may be any geometric shape, such as a triangle, a pentagon, a hexagon, a circle, an ellipse, or the like.

[0049] As shown in Fig. 5(A) to Fig. 5(F), each reflective element 12 of the conductive layer 16 may be one or more linear conductors formed as a thin film on the upper surface of the base layer 13. Fig. 5(A) to Fig. 5(F) are diagrams showing part B of Fig. 2. In these examples, one or more linear conductors 12A to 12C constituting the conductor are arranged surrounding a plurality of conductor-free regions 12a. That is, the reflective element 12 is one in which the conductors and the conductor-free regions 12a are periodically arranged at a predetermined interval. "Linear" means that the length in the longitudinal direction is 3000 times or more the length in the direction perpendicular to the longitudinal direction.

[0050] In this way, when the reflective element 12 is composed of a conductor and a region 12a without a conductor, the area of ​​the reflective element 12 as viewed from the plane is the sum of the area of ​​the conductor and the area of ​​the region 12a without a conductor surrounded by the conductor. Fig. 6 shows an example in which each reflective element 12 includes conductors (first and second linear bodies 12A, 12B) as shown in Fig. 5(A) and a region 12a without a conductor. In Fig. 6, the area of ​​the reflective element 12 as viewed from the plane is the sum of the area of ​​the conductors (first and second linear bodies 12A, 12B) and the area of ​​the region 12a without a conductor colored light gray.

[0051] In this case, the shortest distance L21 between any points on the edges of adjacent reflecting elements 12 is the shortest value of the distance between any point on the conductor of one reflecting element 12 and any point on the conductor of the adjacent reflecting element 12. In Fig. 6, the shortest distance L21 is the distance between the ends of linear bodies 12A, 12B of adjacent reflecting elements 12.

[0052] In the example shown in FIG. 5(A), a plurality of first linear bodies 12A and a plurality of second linear bodies 12B constituting a conductor are arranged at equal intervals along the vertical and horizontal directions of FIG. 5(A), and a region surrounded by two adjacent first linear bodies 12A and two adjacent second linear bodies 12B is a region 12a without a conductor. The region 12a without a conductor is a square of the same shape. In other words, a plurality of regions 12a without a conductor are arranged in the vertical and horizontal directions at intervals of the line width L6 of the linear bodies 12A and 12B. At the intersection where the first linear body 12A along the horizontal direction and the second linear body 12B along the vertical direction overlap, the first linear body 12A and the second linear body 12B are electrically conductive. The line width L6 of the linear bodies 12A, 12B is preferably set to 0.05 μm or more and 15 μm or less. The interval L7 between adjacent linear bodies 12A, 12B in the vertical or horizontal direction (the length of one side of the square non-conductor region 12a) is set to be greater than the wavelength of visible light and smaller than the wavelength of the electromagnetic wave reflected by the electromagnetic wave scatterer 11, and in this example, is set to 2 μm or more and 10 cm or less. More preferably, it is 20 μm or more and 1 cm or less, and even more preferably, it is 25 μm or more and 1 mm or less. Still more preferably, it is 30 μm or more and 250 μm or less. When the non-conductor region 12a is not a square, the maximum length between any two points on the ends of the non-conductor region 12a is set to the above length. The non-conductor region 12a may be filled with the adhesive of the adhesive layer 14.

[0053] In the arrangement of conductors shown in Figure 5(A), the shape of the area 12a without conductors is square, but for example, the distance between adjacent linear bodies 12A extending in the horizontal direction and the distance between adjacent linear bodies 12B extending in the vertical direction may be different, and the shape of the area 12a without conductors may be rectangular.

[0054] The reflecting elements 12 may be arranged in the arrangement patterns shown in Fig. 5(B) to Fig. 5(F). In Fig. 5(B), the conductors are arranged in a brick-laying pattern. A plurality of first linear bodies 12A are arranged horizontally and vertically at a predetermined interval, and a plurality of second linear bodies 12B extending vertically are arranged in a staggered pattern between the first linear bodies 12A adjacent to each other vertically. The staggered pattern refers to a state in which a plurality of second linear bodies 12B extending vertically are arranged horizontally at a predetermined interval, a plurality of second linear bodies 12B forming one row are positioned between a plurality of second linear bodies 12B forming a row adjacent to this row in the vertical direction, and the second linear bodies 12B of every other row are arranged in a straight line. The region 12a without conductors is a region surrounded by two adjacent first linear bodies 12A and two adjacent second linear bodies 12B.

[0055] In FIG. 5(C), the linear bodies 12A to 12C are arranged so that the regions without conductors are triangular. The regions without conductors include a plurality of triangular first regions 12a and a plurality of inverted triangular second regions 12b. The first regions 12a and the second regions 12b are arranged at regular intervals in the horizontal and vertical directions, respectively, and the second regions 12b are arranged between the adjacent first regions 12a. Each of the first region 12a and the second region 12b is an area surrounded by the first to third linear bodies 12A to 12C. The first linear body 12A is arranged along the horizontal direction, the second linear body 12B is arranged along a direction inclined obliquely with respect to the first linear body 12A, and the third linear body 12C is arranged along a direction symmetrical to the second linear body 12B with respect to the first linear body 12A.

[0056] In FIG. 5C, the shape of each of the regions 12a and 12b is an equilateral triangle, but it may be an isosceles triangle or a triangle whose three sides have different lengths.

[0057] 5(D), linear bodies 12A are arranged surrounding regular hexagonal non-conductor regions 12a. Non-conductor regions 12a are arranged vertically in succession at intervals of line width L6 of linear body 12A, and multiple such rows are arranged horizontally. Non-conductor regions 12a in adjacent rows in the horizontal direction are arranged between non-conductor regions 12a adjacent in the vertical direction.

[0058] In FIG. 5(E), there are a plurality of types of non-conductor regions with different shapes. The non-conductor regions include a first region 12a of a regular pentagon surrounded by the linear body 12A, a second region 12b of an inverted regular pentagon, and a third region 12c of a rhombus. The first region 12a to the third region 12c are arranged at regular intervals in the horizontal and vertical directions. In detail, the first region 12a and the second region 12b are arranged adjacent to each other in the vertical direction with an interval of the line width L6 of the linear body 12A, and pairs of the first region 12a and the second region 12b are arranged periodically in the horizontal direction. The third region 12c is arranged between pairs of the first region 12a and the second region 12b adjacent to each other in the horizontal direction. The shapes formed by the first region 12a, the second region 12b, and the third region 12c are arranged at the same period.

[0059] In FIG. 5(F), there are a plurality of types of conductor-free regions with different shapes. The conductor-free regions include a circular first region 12a surrounded by the linear body 12A, a substantially triangular second region 12b, and a substantially inverted triangular third region 12c. The first to third regions 12a to 12c are periodically arranged at regular intervals in the vertical and horizontal directions. The first regions 12a are periodically arranged side by side in the horizontal direction so as to be continuous with an interval of the line width L6 of the linear body 12A. Rows of such first regions 12a are continuously arranged in the vertical direction, and vertically adjacent first regions 12a are arranged between horizontally adjacent first regions 12a.

[0060] 5(A) to (F) show only the conductors of reflecting element 12.

[0061] The conductive layer 16 can be manufactured, for example, by forming a conductive film, forming a pattern by etching, and extracting a conductive thin film having the pattern. Another example is a method in which a photosensitive resist is applied onto a base film provided with a lift-off layer, a pattern is formed by photolithography, a conductor is filled in the patterned portion, and then the conductive thin film having the pattern is extracted. The manufacturing method is not limited to the above, and examples of the conductive layer 16 include a method of adhering a metal thin film and a method of vapor-depositing a metal.

[0062] (Configuration of other layers of the electromagnetic wave scatterer 11) (Base material layer 13) In this embodiment, the base layer 13 has an outer shape formed in a square shape in a plan view. However, the shape is not limited thereto, and may be a rectangle, a circle, an ellipse, a sector, a polygon, a three-dimensional shape, or the like, according to the overall shape of the electromagnetic wave scatterer 11. A synthetic resin sheet is used as the base material of the base layer 13. Examples of the synthetic resin include one or more types selected from the group consisting of PET (polyethylene terephthalate), polyethylene, polypropylene, polyvinyl chloride, polystyrene, polymethyl methacrylate, polyester, polyformaldehyde, polyamide, polyphenylene ether, vinylidene chloride, polyvinyl acetate, polyvinyl acetal, AS resin, ABS resin, acrylic resin, fluororesin, nylon resin, polyacetal resin, polycarbonate resin, polyamide resin, and polyurethane resin.

[0063] In this embodiment, the thickness L2 (length in the vertical direction in FIG. 1) of the base layer 13 is uniform, and the thickness L2 is set to 0.13 mm, but is not limited to this and is appropriately set depending on the manner of use of the electromagnetic wave scatterer 11. The thickness does not have to be uniform, and may be formed, for example, in a wedge shape, or may be formed in a three-dimensional shape having a partially spherical surface or an uneven shape. The base layer 13 may contain any material such as a synthetic resin or any member in addition to the base material.

[0064] (adhesive layer 14) The adhesive layer 14 is made of an adhesive and bonds the protective layer 15 onto the base material layer 13 and the conductive layer 16. The adhesive layer 14 has a size corresponding to the base material layer 13 in a plan view. An adhesive sheet made of synthetic resin or rubber is used as the adhesive of the adhesive layer 14. Examples of the synthetic resin include an acrylic resin, a silicone resin, and a polyvinyl alcohol resin.

[0065] The thickness L4 of the adhesive layer 14 is the distance between the upper surface of the conductive layer 16 and the lower surface of the protective layer 15, and is set to 150 μm in this embodiment, but is not limited to this. The adhesive of the adhesive layer 14 may be filled in the region 12a of the conductive layer 16 that has no conductor or the peripheral end of the base material layer 13 (the portion between the edge of the base material layer 13 and the conductive layer 16). Note that the adhesive layer 14 may contain any substance such as a synthetic resin or any member in addition to the adhesive.

[0066] (Protective layer 15) The protective layer 15 has a size corresponding to the base layer 13 in a plan view, protects the reflective element 12, and is made of a protective material. A synthetic resin sheet (film) is used as the protective material of the protective layer 15. Examples of the synthetic resin include one or more selected from the group consisting of PET (polyethylene terephthalate), COP (cycloolefin polymer), polyethylene, polypropylene, polyvinyl chloride, polystyrene, polymethyl methacrylate, polyester, polyformaldehyde, polyamide, polyphenylene ether, vinylidene chloride, polyvinyl acetate, polyvinyl acetal, AS resin, ABS resin, acrylic resin, fluororesin, nylon resin, polyacetal resin, polycarbonate resin, polyamide resin, and polyurethane resin. The thickness L5 of the protective layer 15 is preferably set to 0.02 mm or more and 0.30 mm or less. The protective layer 15 may contain any substance such as a synthetic resin or any member in addition to the protective material.

[0067] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention. The dimensions, materials, shapes, and relative arrangements of the components described as embodiments or shown in the drawings are merely illustrative examples, and are not intended to limit the scope of the present invention. For example, expressions expressing relative or absolute arrangements such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" not only strictly express such arrangements, but also express a state in which they are relatively displaced with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions expressing that things are in an equal state, such as "same," "equal," and "homogeneous," not only strictly express a state in which they are equal, but also express a state in which there is a tolerance or a difference to the extent that the same function is obtained. For example, expressions expressing shapes such as a square shape or a cylindrical shape not only express shapes such as a square shape or a cylindrical shape in the strict geometric sense, but also express shapes including uneven parts and chamfered parts to the extent that the same effect is obtained. The expressions "comprise", "include", "have", "include", or "have" one component are not exclusive expressions that exclude the presence of other components. In addition, expressions with "approximately" such as "approximately parallel" or "approximately perpendicular" may be used. For example, "approximately parallel" means that it is substantially "parallel", and includes not only a strictly "parallel" state but also an error of a few degrees. The same applies to other expressions with "approximately". In addition, expressions with "part" such as "end" may be used. For example, "end" means a part having a certain range that includes the "end". The same applies to other expressions with "part". [Explanation of symbols]

[0068] 11 Electromagnetic wave scatterer 12 Conductors 13 Base material layer 14 Adhesive layer 15 Protective layer 16 Conductive layer λ wavelength L21 The shortest distance between any points on the edge of a conductive layer Wz Maximum height waviness

Claims

1. A sheet-like electromagnetic wave scatterer comprising a conductive layer including a reflecting element that reflects electromagnetic waves, and a base layer that supports the conductive layer, An electromagnetic wave scatterer, wherein the maximum height waviness of a cross-sectional curve of the reflecting element in any cross section along a thickness direction of the electromagnetic wave scatterer is 0.5 mm or more.

2. 2. The electromagnetic wave scatterer according to claim 1, having a thickness of 0.05 mm or more and 10 mm or less.

3. If the wavelength of the electromagnetic wave reflected by the electromagnetic wave scatterer is λ, then Radar cross section (RCS) is 200 λ ２ That's all.

3. The electromagnetic wave scatterer according to claim 1, wherein a 3 dB beam width, which is 3 dB less than the maximum gain, is 1 degree or more.

4. The reflecting element is formed in plurality on the base layer, If the wavelength of the electromagnetic wave reflected by the electromagnetic wave scatterer is λ, then From a plan view, The area of ​​at least one of the reflective elements is λ ２ More than 400 λ ２ It is set to:

3. The electromagnetic wave scatterer according to claim 1, wherein the shortest distance between any points on the edge of adjacent reflecting elements is set to 1.1 .lambda. or more.

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