Reflectarray with function layer

Abstract

To provide a reflectarray capable of suppressing foam with a micro fable size.SOLUTION: A reflectarray of the present invention comprises a ground layer, a dielectric layer, and an element pattern, and comprises an additional function layer that covers at least an upper surface and a side surface of the element pattern. A thickness L(μm) of the element pattern satisfies the formula (1): 1.0≤L(1). The side surface includes a first end connected to the lower surface of the element pattern, and a second end connected to the upper surface. In a cross section, an angle α(°) of a straight line connecting the first end and the second end, and a perpendicular to the lower surface from the second end satisfy the formula (2): α≥10 (2). When the side surface is divided at a ground point of N at an equal interval to the thickness direction by using the N calculated from the formula (3), an angle βi of a straight line connecting a first (i-1) ground point with a first i ground point in the cross section and a perpendicular from the second end to the lower surface is an arbitrary i, (where, i is an integer value satisfying the equation of 1≤i≤N+1), and is 0 or larger: N=[L](3).SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a reflective array with a functional layer.

Background Art

[0002] With the progress of digitalization in society, the data communication speed in wireless communication has improved dramatically, and the associated high-frequency electromagnetic waves have advanced. However, since electromagnetic waves become more direct as the frequency increases, electromagnetic waves do not penetrate into the shadows of buildings and the like, and dead zones where communication is impossible are likely to occur. For these reasons, in order to realize 5G and 6G communications over a wide area, it is necessary to increase the number of base stations. However, since increasing the number of base stations requires a large amount of cost, it is difficult to quickly increase the number of base stations. In recent years, in order to solve these problems, a reflective array has been proposed as a technique for controlling the direction of electromagnetic waves. A reflective array (electromagnetic wave reflector) is a member that reflects electromagnetic waves, and includes not only those that cause symmetric reflection with equal incident and reflection angles, but also those that cause asymmetric reflection with different incident and reflection angles, those that scatter electromagnetic waves in multiple directions, and those that collect electromagnetic waves at specific locations. Reflective arrays are described in Patent Documents 1 to 3.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] A reflect array generally has a structure in which an element pattern is formed of a conductor layer on a base material layer, and an additional functional layer such as a protective layer is laminated on and covers the conductor layer. When bubbles are generated around the element pattern in the process of laminating the additional functional layer on the element pattern, the reflection phase in the cell where the element pattern is located changes greatly from the designed value. When the proportion of cells with such a problem exceeds a certain ratio, it has an adverse effect such as an increase in unnecessary reflection and a decrease in the reflection intensity in the desired direction. In the reflect arrays of Patent Document 1 or 2, there is no recognition of the problem of bubble mixing in such an element pattern and the problem of suppression.

[0005] A bubble is a particle in which a gas is enclosed inside or on the surface of a liquid or a solid, and is covered with a single surfactant layer. Foam is an aggregate state of bubbles and may be covered with a double surfactant layer. A bubble is a general term including bubbles and foam. The particles of bubbles can take various shapes such as spheres and ellipsoids. The size of a bubble (bubble diameter) is defined as the length of the longest line segment among the line segments connecting two points on the contour line of the bubble (described later).

[0006] The inventor noticed that among bubbles, ultrafine bubbles with a bubble diameter of less than 1 μm are negatively charged in neutral water, so the bubbles repel each other and do not combine, while microfab bubbles with a bubble diameter of approximately 1 μm or more combine when the bubbles come into contact with each other to form a single larger bubble or foam, which has a greater adverse effect on the reflection characteristics.

[0007] Although Patent Document 3 is in the technology of an antenna and has a different technical field from a reflect array, it is described that an inclined surface or a curved surface is provided on the side surface shape of the conductor layer to suppress the generation of a gap between the conductor layer and the additional functional layer. However, there is no recognition of the problem focusing on the influence on the reflection characteristics according to the size of the bubbles, and it is not clear about the side surface shape of the element pattern aimed at suppressing bubbles of microfab size in particular. Therefore, an object of the present invention is to provide a reflect array capable of suppressing bubbles of microfab size.

Means for Solving the Problem

[0008] To solve the above problems, one of the representative reflect arrays with a functional layer of the present invention includes a ground layer, a dielectric layer, and an element pattern, and has an additional functional layer covering at least the upper surface and the side surface of the element pattern. The thickness L (μm) of the element pattern satisfies the formula (1), 1.0 ≦ L (1) The side surface has a first end connected to the lower surface of the element pattern and a second end connected to the upper surface. The angle α (°) between the straight line connecting the first end and the second end in the cross section and the perpendicular line from the second end to the lower surface satisfies the formula (2), α ≧ 10 (2) When the side surface is divided at N points at equal intervals in the thickness direction using N obtained from the formula (3), the angle βi between the straight line connecting the (i - 1)th point and the ith point in the cross section and the perpendicular line from the second end to the lower surface satisfies the formula (4) for any i. This is the feature of the present invention. N = [L] (3) βi ≧ 0 (4) (i is an integer satisfying 1 ≦ i ≦ N + 1.)

Advantages of the Invention

[0009] According to the present invention, it is possible to provide a reflect array capable of suppressing microfabric-sized bubbles. Problems, configurations, and effects other than those described above will be clarified by the description in the following embodiments for implementation.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 4

Figure 5

Figure 6

Figure 7A

Figure 7B

Figure 8

Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited by this embodiment. Also, in the description of the drawings, the same parts are denoted by the same reference numerals.

[0012] In the following description, an xyz coordinate system is applied, and it is assumed that the reflect array is formed on the xy plane. The shape of the reflect array in the xy plane is arbitrary, but in the following description, it is assumed that the reflect array is the simplest quadrilateral, and each side of the reflect array is formed to be parallel to the x-axis and the y-axis, respectively. Also, the ground layer, dielectric layer, element pattern, and functional layer are laminated in this order along the positive direction of the z-axis.

[0013] The term "surface" may refer not only to the surface of a plate-like member but also to the interface of a layer contained in the plate-like member that is substantially parallel to the surface of the plate-like member. Further, the "upper surface" and "lower surface" mean the surfaces shown above or below in the drawing when the plate-like member or the layer contained in the plate-like member is illustrated. The upper direction means the positive direction of the z-axis, and the lower direction means the negative direction. Note that the "upper surface" and "lower surface" may also be referred to by numbers such as "first surface" and "second surface".

[0014] The "side surface" refers to the surface connecting the "upper surface" and the "lower surface". When the shape of the side surface is expressed as a taper, it means that all the side surfaces of the structure are inclined. When the shape of the side surface is expressed as a progressive taper, it means that all the side surfaces of the structure are inclined so as to be displaced outward from the upper surface to the lower surface.

[0015] The "cross section" refers to a part or all of the surface obtained by cutting the reflectarray in the z-axis direction along an arbitrary line along the x-axis or y-axis in the xyz coordinate system.

[0016] The distance in the z-axis direction in the xyz coordinate system may be referred to as the "thickness". Also, the z-axis direction may be referred to as the thickness direction.

[0017] (Reflection control region) The reflection control region refers to a part of the region constituting the reflectarray. The reflection control region is the smallest region that can reflect the electromagnetic wave incident on the region in a predetermined direction. And the reflectarray is composed of one or more combinations of the reflection control regions. When referring to the reflection control region, in addition to the two-dimensional region where the electromagnetic wave is in a direction parallel to the incident region, it shall also include the layer structure formed in the direction perpendicular to the region.

[0018] The unit cell refers to a region obtained by dividing the reflection control region. One element pattern is included in the unit cell. Two or more unit cells exist within one reflection control region. Define the size of one side of a single unit cell in the x-axis direction as Ux and the size in the y-axis direction as Uy. Define the size (length) of the side where a plurality of unit cells are arranged in the x-axis direction within one reflection control region as Sx.

[0019] FIG. 1 is an example of a schematic diagram showing an enlarged view of the reflection control region portion. FIG. 1(a) is a perspective view of the reflection control region, FIG. 1(b) is a cross-sectional view in the xz plane obtained by cutting the reflection control region at y = Uy / 2, and FIG. 1(c) is a cross-sectional view in the yz plane obtained by cutting an arbitrary unit cell of the reflection control region at x = Ux / 2. An element pattern 1 having an element side surface 5 is formed on one xy plane of the dielectric layer 2, and a ground layer 3 is formed on the other xy plane. And an additional function layer 4 is formed so as to cover the entire element side surface 5 of the element pattern 1. When the unit cell is obtained by equally dividing the reflection control region into n parts along a predetermined direction, Ux is Sx / n. However, n is an integer of 2 or more (in the example of FIG. 1, the long side in the x-axis direction is divided into three square unit cells 1 1 、1 2 、1 3 and the reflection control region is constituted.).

[0020] (Design of Reflectarray) The design of the reflectarray is carried out according to the following procedure. First, determine the length Sx of the long side of the reflection control region by the following formula (5). Here, Sx is the length of the long side of the reflection control region, λ is the wavelength of the electromagnetic wave applied to the reflectarray (hereinafter, also referred to as "wavelength at the operating (design) frequency"), θi is the incident angle, and θr is the reflection angle. Note that the incident angle θi and the reflection angle θr are values measured in the zx plane. Here, the direction parallel to the z-axis is set as θi = θr = 0°, the angle of rotation in the positive direction of the x-axis is θi = 0 to 90°, and the angle of rotation in the negative direction is θr = 0 to 90°.

Equation

[0021] Next, the reflection phase required in each reflection control region is obtained by the following equation (6).

Equation

Equation

Equation

Equation

[0022] After obtaining the reflection phase by the above method, the shape of the element pattern is changed so as to satisfy the reflection phase in each unit cell, and simulation is performed to optimize the shape of the element pattern. When an electromagnetic wave is incident on the element pattern, the relationship between the shape of the element pattern and the reflection phase can be obtained by simulation using, for example, an electromagnetic analysis tool (High Frequency Structure Simulator: HFSS) or the like.

[0023] The components of the reflectarray will be described in more detail. (Element Pattern) The element pattern is provided to asymmetrically reflect the incident electromagnetic wave and reflect it in a direction different from symmetric reflection. The thickness of the element pattern is, for example, 10 nm or more and 105 μm or less.

[0024] The element pattern preferably has a surface resistance value of 100 Ω / square or less. The material used for the element pattern is, for example, composed of a conductive material. As such a material, the same material as that used for the ground layer can be used. A conductive inorganic material or an organic material may be formed into a film on the dielectric layer. From the viewpoints of flexibility, film formability, stability, sheet resistance value, and low cost, as a forming method described later, it is preferable to use a film formed by a vapor deposition method as the element pattern.

[0025] Examples of the shape of the element pattern include, but are not limited to, a cross patch. FIG. 2 is a diagram showing an example of the element pattern shape. As shown in FIG. 2, a reflect array may be formed with an element pattern having an arbitrary shape that reflects radio waves, such as a continuous film, a mesh shape, or a punching shape. For example, instead of a cross patch (FIG. 2(a)), a cube patch (FIG. 2(b)), a cylinder patch (FIG. 2(c)), a triangular prism patch (FIG. 2(d)), an Jerusalem cross patch (FIG. 2(e)), a plurality of parallel conductive patterns (FIG. 2(f)), a ring-shaped conductive pattern (FIG. 2(g)), or an element pattern combining a plurality of these (FIG. 2(h)) may be used.

[0026] The case where the element pattern is a cross patch will be described. A cross patch refers to a shape in which two rectangular patches are orthogonal in the xy plane. Let the length of the element pattern of the cross patch be the element length, and the width of the element pattern of the cross patch be the element width. By changing either or both of the element length and the element width, the reflection phase of the unit cell is controlled. When fixing the element length, it is desirable to set the value of the element length as large as possible within the unit cell. By setting it large, it becomes easier to obtain the desired reflection phase characteristics. Also, when fixing the element width, it is desirable to set the value of the element width as large as possible within the unit cell. By setting the value of the element width large, the slope of the reflection phase becomes gentle, so the processing accuracy during processing is widened. Note that the element length is not limited to being set for the element pattern of the cross patch, and can also be set for element patterns having other shapes. Also, the element length can be set to a common length in the reflection control region, or can be set to different lengths for each element pattern included in the reflection control region.

[0027] As a method for forming the element pattern, a method of forming a conductive material on the dielectric layer over the entire surface to form a continuous film and then forming the element pattern by processing, or a method of directly forming an element pattern layer on the dielectric layer can be employed.

[0028] As a method for forming a continuous film of a conductive material over the entire surface on the dielectric layer, in the case of a metal, dry coating such as sputtering or vapor deposition, wet coating such as plating or gravure coating or die coating using metal ink, etc. can be selected. Or, a rolled metal plate can be bonded to the dielectric layer. Similarly, for an inorganic oxide material, a continuous film can be formed by dry coating, and for an organic-based material, a continuous film can be formed by wet coating. Also, painting or spraying methods may be used. For the formed continuous film, unnecessary portions are removed using removal processing such as dry etching, wet etching, cutting, etc., thereby forming the element pattern.

[0029] When performing removal processing by an etching method, the ends of the element patterns constituting the reflect array may have an R (in other words, may be rounded), pinholes may occur, the cross-sectional shape may be a forward taper shape or a reverse taper shape, or undercutting or over-etching may occur. Although such shape changes are assumed to occur during etching processing, in the basic configuration, if the direction of the main beam among the reflected electromagnetic waves is within the range of approximately ±5° of the designed reflection angle, it is considered acceptable as the reflection phase characteristics. The same is true when formed by cutting, printing methods, dry coating, plating, painting, or spraying methods.

[0030] In addition, as a method of directly forming element patterns on the dielectric layer, methods such as printing using relief printing, lithography, intaglio printing, screen printing, transfer printing, etc., or masking the portions other than the element pattern portions on the dielectric layer with masking tape, masking agents, etc., and then forming the element patterns using dry coating, plating, painting, or spraying methods can also be used.

[0031] The cross-sectional shape of the element pattern is preferably a forward taper shape in which the base widens from the upper surface to the lower surface. By having a forward taper shape, the surface area of the element pattern increases, the adhesion with the functional layer during the lamination of the functional layer described later can be increased, and the mixing of air bubbles can be suppressed.

[0032] The material of the element pattern may be the same as that of the ground layer or may be a different material. For example, it is also possible that at least one of the ground layer or the element pattern layer is formed of Cu or Al. Since Cu has excellent conductivity, conductor loss can be reduced. Since Al has a small density, is lightweight, and has a low cost, a lightweight and inexpensive reflect array can be formed.

[0033] When the element pattern is in a mesh shape, the line width of the mesh is preferably 5 μm or more and 30 μm or less, more preferably 6 μm or more and 15 μm or less. The line interval of the mesh is preferably 50 μm or more and 500 μm or less, more preferably 100 μm or more and 300 μm or less. Also, when the wavelength at the operating frequency is λ, the line interval of the mesh is preferably 0.5×λ or less, more preferably 0.1×λ or less, and even more preferably 0.01×λ or less. If the line interval of the mesh is 0.5×λ or less, the performance can be ensured. Also, the line interval of the mesh may be 0.001×λ or more. When using a metal mesh or a transparent conductive material, the reflect array exhibits visible light transmissibility, making it possible to maintain the landscape after installation. When the element pattern is in a mesh shape or when a transparent conductive material is used, the reflect array exhibits visible light transmissibility, making it possible to maintain the landscape after installation.

[0034] When the form of the element pattern is a thin film, the adhesion with the additional functional layer and the adhesion improvement layer is improved, and the flexibility of the reflect array can be improved, thereby enabling use on a curved surface and implementing a roll-to-roll production process.

[0035] When forming the element pattern using a thin film, its thickness is preferably greater than the skin depth calculated from the following formula (10). However, d is the skin depth, ω is the angular frequency, μ is the magnetic permeability of the material, and σ is the conductivity of the material.

Equation

[0036] To increase the radio wave reflection efficiency, reducing the radio wave loss by the element can be mentioned. Therefore, the smaller the surface roughness of the element, the better.

[0037] (Dielectric) Examples of the dielectric include not only a single resin but also a composite material in which paper, glass fiber, carbon fiber, etc. are impregnated with resin. Examples of single resins include polyethylene (εr = 2.2 - 2.4), polypropylene (εr = 2.0 - 2.6), polystyrene (εr = 2.4 - 2.6), polyvinyl chloride (εr = 2.8 - 8.0), AS resin (εr = 2.6 - 3.1), ABS resin (εr = 2.4 - 4.1), polyethylene terephthalate (εr = 2.9 - 3.0), acrylic resin (εr = 2.7 - 4.5), urethane resin (εr = 4.0 - 7.1), epoxy resin (εr = 2.5 - 6.0), nylon (εr = 3.0 - 5.0), polyimide (εr = 2.4 - 2.7), fluororesin (εr = 2.0 - 2.6), polycarbonate (εr = 2.9 - 8.9), polyphenylene ether (εr = 2.8 - 8.2), polyphenylene sulfide (εr = 3.2 - 4.6), polyvinylidene fluoride (εr = 6.4 - 10.0), polyethylene naphthalate (εr = 2.9), phenolic resin (εr = 3.0 - 12.0), cycloolefin polymer (εr = 2.3 - 2.5), etc. Here, εr represents the relative permittivity. In particular, from the viewpoints of low cost and excellent versatility, it is preferable to use polyethylene (PS), polyethylene terephthalate (PET), cycloolefin polymer (COP), etc. Also, the dielectric layer can be a single layer or a multilayer. Further, the dielectric layer may use a foam obtained by foaming the above materials. Also, as the foam, a foam with high flexibility is preferably used. Examples of composite materials include composite materials such as paper / phenolic resin, paper / epoxy resin, glass / epoxy resin, and glass / fluororesin. In addition, from the viewpoint of permittivity adjustment, the use of mixtures containing resin components with each other or a dielectric compound and a resin component can be mentioned. The relative permittivity in the mixture can be adjusted according to the selection of the dielectric compound and its content.

[0038] The relative permittivity of the mixture can be predicted, for example, using the Maxwell - Garnett rule. In a mixture of dielectric A with relative permittivity εa and dielectric B with relative permittivity εb, when the volume fraction of dielectric A is δa, the relative permittivity εm of the mixture is shown by the relational expression of the following formula (11).

Equation

[0039] Examples of the dielectric compound include barium titanate (εr = 250 to 20000), titanium oxide (εr = 83 to 183), lead titanate zirconate, strontium bismuth tantalate, bismuth ferrite, and the like.

[0040] When a dielectric having transparency is used, the reflect array exhibits visible light transmittance, making it possible to maintain the landscape after installation.

[0041] The relative permittivity of the dielectric layer is preferably in the range of 1 or more and 20 or less, more preferably in the range of 1 or more and 10 or less, and even more preferably in the range of 2 or more and 4 or less. When the relative permittivity is within the above range, it tends to be easy to obtain desired reflection phase characteristics in the reflect array. Also, the dielectric loss tangent is preferably in the range of 0.00005 or more and 0.01 or less, and preferably in the range of 0.00005 or more and 0.001 or less. When it is within the above range, a reflect array with less dielectric loss can be fabricated.

[0042] The dielectric layer can be formed, for example, by wet coating such as die coating, comma coating, and gravure coating, melt extrusion methods such as the T-die method and the inflation method, calendar film forming method, solution casting method, hot pressing method, and the like. Also, a coextrusion method in which a plurality of resins are extruded in multiple layers to form a film may be used.

[0043] The thickness of the dielectric layer is appropriately selected according to the design frequency. When the design frequency is 28 GHz, it is preferably 40 μm or more and 250 μm or less, and more preferably 50 μm or more and 200 μm or less. If it is too thin, it becomes difficult to ensure the reflection phase, making it difficult to design the reflectarray. On the other hand, if it is too thick, there is a tendency that it becomes difficult to ensure the reflection phase, the flexibility is lost, the total thickness of the reflectarray becomes thick, etc., making it difficult to save space. Therefore, the thickness of the dielectric layer is preferably 250 μm or less. When the design frequency is 60 GHz, the thickness of the dielectric layer is preferably 10 μm or more and 250 μm or less. When the design frequency is 100 GHz or more, if the thickness of the dielectric layer is about several μm or more and 100 μm or less, it is easy to design the reflectarray.

[0044] (Ground layer) The ground layer is provided to reflect the electromagnetic waves reaching the reflectarray. It is also used to support and protect the dielectric layer. As the material of the ground layer, a conductive material such as an inorganic oxide material, a metal material, or a conductive organic material is used. The thickness of the ground layer is, for example, 10 nm or more and 105 μm or less.

[0045] For example, as the inorganic oxide materials and metal materials, indium tin oxide (ITO), indium zinc oxide (IZO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO), tin antimonide oxide, Ag, Al, Au, Pt, Pd, Cu, Co, Cr, In, Ag-Cu, Cu-Au, Ni, etc. are used. Further, nanoparticles or nanowires containing at least one of these materials may be used. Examples of the conductive organic materials include polythiophene derivatives, polyacetylene derivatives, polyaniline derivatives, polypyrrole derivatives, carbon nanotubes, graphene, etc. Particularly from the viewpoints of material cost, conductivity, and film-forming property, Cu and Al are preferable. Further, in order to reflect electromagnetic waves, it is desirable that the surface resistance value of the ground layer is 100 Ω / sq or less. If this condition can be satisfied, a reflective array having transparency can be produced by using ITO, a mixture of polyethylenedioxythiophene (PEDOT) and polystyrene sulfonic acid (PSS) (PEDOT / PSS), etc.

[0046] Examples of the form of using the above materials include a continuous film, a mesh shape, a punching shape, and a periodic structure. Here, a mesh refers to a state in which a mesh-like through-hole (opening) is formed in the plane of a conductor. When the conductor is formed in a mesh shape, the mesh openings may be square or rhombic. When the mesh openings are formed in a square shape, it is preferable that the mesh openings are square. If the mesh openings are square, the design property is good. Also, a random shape by a self-assembly method may be used. By making it a random shape, moiré can be prevented. When processing the metal into a mesh shape, methods such as punching of a metal plate and etching of a metal plate can be adopted. When the ground layer is in a mesh shape or when a transparent conductive material is used, the reflective array exhibits visible light transmittance and makes it possible to maintain the landscape after installation.

[0047] When the ground layer is in a mesh shape, the line width of the mesh is preferably 5 μm or more and 30 μm or less, more preferably 6 μm or more and 15 μm or less. The line interval of the mesh is preferably 50 μm or more and 500 μm or less, more preferably 100 μm or more and 300 μm or less. Further, when the wavelength at the operating frequency is λ, the line interval of the mesh is preferably 0.5×λ or less, more preferably 0.1×λ or less, and even more preferably 0.01×λ or less. If the line interval of the mesh is 0.5×λ or less, the performance can be ensured. Also, the line interval of the mesh may be 0.001×λ or more.

[0048] As a method for forming the ground layer, in the case of using a metal material, dry coating such as sputtering or vapor deposition, gravure coating by inking the metal material, wet coating such as die coating, surface treatment such as plating, etc. can be selected. Alternatively, as the ground layer, a rolled metal plate may be used. In the case of using an inorganic oxide material, dry coating can be selected as a method for forming the ground layer. In the case of using an organic material, wet coating can be selected as a method for forming the ground layer. Also, it may be formed by painting or spraying.

[0049] When the form of the ground layer is a thin film formed by plating or vapor deposition, etc., it is possible to improve the flexibility of the reflect array, thereby enabling use on a curved surface and implementing a roll-to-roll production process.

[0050] When the form of the ground layer is a thin film, its thickness is preferably greater than the skin depth calculated from Equation (10) as in the case of the element pattern. Also, in order to increase the reflection efficiency of electromagnetic waves, it is possible to reduce the loss due to the ground layer. Therefore, the surface roughness of the ground layer is preferably small.

[0051] When the form of the ground layer is a periodic structure, a function of selectively reflecting or transmitting a specific frequency can be exhibited. For example, when a structure in which patch-shaped conductive patterns are periodically arranged is used as the ground layer, it becomes possible to reflect only a specific frequency, so that a function of transmitting frequencies other than the operating frequency can be imparted. Further, when a structure in which holes are periodically provided at locations where there is no conductive material is used, it is possible to design a reflectarray that asymmetrically reflects the operating frequency and transmits only a specific frequency.

[0052] In the present disclosure, surface resistance measurement is performed in accordance with JIS-K-7194. As the surface resistance measurement method, a measurement method such as a four-terminal method, a two-terminal method, a four-probe method, a dielectric method, or an eddy current method can be appropriately selected. The surface resistance value of the ground layer can be measured using, for example, Loresta GP MCP-T610 (trade name, manufactured by Mitsubishi Chemical Analytech Co., Ltd.).

[0053] (Additional functional layer) The additional functional layer can select its function as needed. Examples of the functions to be added include deterioration prevention, designability, protection / scratch resistance, waterproofness, gas / water vapor barrier property, flame retardancy, non-combustibility, self-extinguishing property, weather resistance, antifouling, antibacterial / antiviral, chemical resistance, deodorization property, adhesiveness / adhesion, etc. One of these functions may be added, or a plurality of them may be combined. The thickness of the additional functional layer is, for example, 5 μm or more and 6 mm or less.

[0054] Examples of the method of laminating the sheet-shaped additional functional layer include bonding by using lamination, extrusion lamination, etc., and examples of the method of applying the liquid additional functional layer include printing, coating, dry lamination, wet lamination, etc., but the method is not limited thereto. Further, when the additional functional layer does not have adhesiveness or adhesivity, there is a method of adhering it to the reflectarray using an adhesion improvement layer (adhesive).

[0055] Weather resistance As causes of deterioration of the reflective array, oxidation due to exposure to the atmosphere, absorption of water vapor, and alteration by light (ultraviolet rays) such as sunlight are conceivable. In order to prevent deterioration by oxygen and water vapor, it is conceivable to provide a layer with excellent gas barrier properties, such as a barrier film, on the surface of the reflective array. Further, in particular, to prevent deterioration by oxygen, it is preferable that the oxygen permeability of the functional layer is 500 cc / m 2 ·atm·day or less. If this condition can be satisfied, films may be laminated, or an overcoat layer may be provided by dry coating or wet coating. These layers may be single layers, or a plurality of them may be combined or laminated. Examples of the barrier film include single films such as ethylene-vinyl alcohol copolymer resins, coextruded multilayer nylon (Ny) films, and wet-coated films with a vinylidene chloride (PVDC) coat or a polyvinyl alcohol (PVA) coat.

[0056] Further, in order to prevent deterioration of the dielectric layer, an antioxidant, a deterioration inhibitor, or an antioxidant material may be added during the formation of the dielectric layer. Similarly, when preventing deterioration by water vapor, it is preferable to provide a layer with a water vapor permeability of 300 g / m 2 ·day or less. When preventing light from sunlight or the like, it is conceivable to provide a film having UV cut properties or a layer having light shielding properties. Further, an ultraviolet ray scattering agent, an ultraviolet ray absorber, or a light stabilizer may be added. Examples of the UV cut film include vinyl chloride-based resins and polyolefin-based resins.

[0057] Design characteristics When a reflect array is installed, for example, on the exterior or interior of a building, it is conceivable to endow it with a design property in order to harmonize with the space. Specifically, a design property can be imparted by bonding a sheet-like material with a design applied thereto to the reflect array using an adhesive, or by welding and attaching the sheet-like material to the reflect array by applying heat and pressure. For example, a decorative sheet in which a printed pattern and a surface embossed pattern are synchronized by laminating a base sheet, an underpattern layer, and a transparent thermoplastic resin layer in this order, or a decorative sheet having a color similar to that of real wood or stone by laminating a pattern layer, a transparent resin layer, and a surface protection layer in this order can be mentioned.

[0058] Protection and abrasion resistance Protection and abrasion resistance refer to the function of preventing the reflect array from being damaged or preventing the deterioration of the reflect array itself. As a method of imparting such a function, the reflect array can be subjected to a coating process to increase the surface hardness, or a synthetic resin film can be laminated. As an evaluation of protection and abrasion resistance, it is preferably carried out by a pencil hardness test based on JIS K5600-5-4 and is H or higher. Also, when rubbed with steel wool (#0000) under a load of 1,000 gf / cm 2 it is preferable that no scratches occur until the number of reciprocating sliding times exceeds 1,000 times. Examples of the synthetic resin include polyethylene terephthalate, 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, polyurethane resin, and the like.

[0059] Flame retardancy, nonflammability, self-extinguishing property As a method of imparting flame retardancy and non-combustibility to a reflect array, it can be imparted by laminating non-combustible materials, semi-non-combustible materials, and flame-retardant materials to which the fire protection certification specified in the Building Standards Act is applied. For example, there are flame-retardant fibers, flame-retardant plastics, non-combustible paints, flame-retardant paints, etc. Examples of flame-retardant fibers include halogen-based compounds, phosphorus-based compounds, vinylon fibers, polyetherimide fibers, aramid fibers, polyester fibers, vinylon fibers, etc. Examples of flame-retardant plastics include those obtained by adding inorganic flame retardants such as halogen-based, phosphorus-based, aluminum hydroxide, and magnesium hydroxide to plastic materials. Also, materials having self-extinguishing properties include nylon, polycarbonate, vinyl chloride, etc.

[0060] Antifouling, antibacterial, and antiviral properties As a method of imparting antifouling properties to a reflect array, it is felt that laminating or coating a substrate having hydrophilicity or water repellency can be done. As materials having hydrophilicity, photocatalytic materials, silica-based materials, etc. can be used. As materials having water repellency, fluororesin-based, silicone-based, etc. materials can be used. As antibacterial and antiviral materials, materials containing photocatalytic materials, chlorine-based, organic-based containing cationic polymers as components, metal-supported systems such as silver and zinc, etc. can be used. As forming methods, methods such as laminating as these material films or using them for coating processing, and mixing during the formation of the dielectric layer can be adopted.

[0061] (Adhesion improvement layer) The adhesion improvement layer is a layer having an adhesive force for adhering layers to each other. The adhesion improvement layer may be composed of two or more layers, or may have a configuration in which a plurality of materials are combined. In the present embodiment, the adhesion improvement layer adheres the ground layer and the dielectric layer, or the dielectric layer and the element pattern, or the dielectric layer and the element pattern and the additional function layer, and is composed of an adhesive. The adhesive may be a water-dispersion adhesive, a solution adhesive, a solventless adhesive, or a solid adhesive. Examples of the adhesive include epoxy resin adhesives, polyvinyl acetate adhesives, nitrile rubber adhesives, phenolic resin adhesives, vinyl acetate adhesives, chloroprene rubber adhesives, acrylic resin adhesives, polyvinyl alcohol resin adhesives, silicone rubber adhesives, styrene-butadiene rubber adhesives, urethane adhesives, and the like. Note that the adhesion improvement layer may contain substances such as arbitrary synthetic resins and arbitrary members in addition to the adhesive. The thickness of the adhesion improvement layer is, for example, 5 μm or more and 500 μm or less.

[0062] When the additional function layer has no adhesiveness or adhesivity, the adhesion improvement layer can be used to bond it to the reflect array. The functional layer is a general term including a single-layer or multi-layer additional function layer, a single-layer or multi-layer adhesion improvement layer, or a layer in which a single or a plurality of additional function layers and adhesion improvement layers are stacked.

[0063] (Installation layer) The installation layer is a layer for supporting and fixing the reflect array to a support. For example, an adhesive layer, an adhesive layer, or the use of a magnet when the support is made of metal can be mentioned. When a magnet is used, the position and angle of the reflect array can be easily changed.

[0064] (Support) The reflective array is installed on a support. As the support, new panels or poles can be installed, or existing billboards, walls, ceilings, etc. can be used. The support preferably has a mechanism capable of adjusting the angle of the reflective array in the vertical or horizontal direction, and more preferably has a mechanism capable of moving the position of the reflective array vertically, horizontally, and laterally. The reflective array is installed on the support and used as a reflective array device.

[0065] (Variations in layer structure) Figures 3A and 3B (hereinafter collectively referred to as Figure 3 for convenience) are schematic diagrams showing examples of variations in the layer structure of the reflective array. However, the layer structure is not limited to this example. Figure 3(a) shows a configuration in which an additional function layer 4 is laminated on the upper surface of a configuration in which a ground layer 3, a dielectric layer 2, and an element pattern 1 are laminated (hereinafter referred to as the "basic configuration"), and the adjacent element patterns 1 are connected by a groove formed in the additional function layer 4. Figure 3(b) shows a mode similar to Figure 3(a) except that a gap where the additional function layer 4 does not exist is formed between adjacent element patterns 1. Figure 3(c) shows a mode in which the additional function layer 4 is uniformly laminated on the upper and lower surfaces of the basic configuration. Figure 3(d) shows a mode in which the additional function layer 4 is uniformly laminated so as to cover not only the upper and lower surfaces of the basic configuration but also the side surfaces.

[0066] Figure 3(e) shows a mode in which an adhesion improvement layer 6 and an additional function layer 4 are uniformly laminated on the upper surface of the basic configuration. Figure 3(f) shows a mode similar to Figure 3(e) except that a gap where neither the additional function layer 4 nor the adhesion improvement layer 6 exists is formed between adjacent element patterns 1. Figure 3(g) shows a mode in which an adhesion improvement layer 6 and an additional function layer 4 are uniformly laminated on the upper and lower surfaces of the basic configuration, respectively. FIG. 3(h) shows a mode in which the additional function layer 4 is uniformly laminated on the upper surface of the basic configuration, and the adhesion improvement layer 6 is further laminated between the dielectric layer 2 and the element pattern 1 and between the dielectric layer 2 and the ground layer 3.

[0067] (Entrainment of air bubbles) When a functional layer is laminated on the reflect array of the basic configuration, the functional layer may contain a plurality of bubbles, but it is preferable that the number of bubbles is small because it has an adverse effect on the appearance of the reflect array and the performance of the reflector. In particular, the bubbles on the side surface of the element pattern change the reflection phase in the unit cell, and strongly suppress the occurrence thereof because it has an adverse effect such as an increase in unnecessary reflection and a decrease in the reflection intensity in the desired direction. Further, the larger the bubble diameter is with respect to the wavelength of the radio wave, the greater the above-mentioned adverse effect becomes. From the above viewpoints, for example, when using radio waves in the band from 1 GHz to 300 GHz, the bubble diameter of the bubbles on the element side surface is preferably less than 100 μm.

[0068] For example, for 100 randomly selected element patterns on the reflect array, it is preferable that the number of element patterns having bubbles with a bubble diameter of 100 μm or more on the side surface is less than 5, more preferably less than 3, and even more preferably 0.

[0069] FIG. 4 is a photograph of observing a part of the element pattern from the upper surface of the functional layer using an optical microscope. When the upper surface of the element pattern has a transparent or translucent adhesion improvement layer and an opaque additional function layer, the additional function layer is removed by a method such as peeling, scraping, or dissolving while leaving the adhesion improvement layer, and the entire circumference of the element pattern is observed from the upper surface of the adhesion improvement layer using an optical microscope. When the element pattern cannot be observed by the above method, the reflect array is cut in the thickness direction, and the cross section of the element pattern is observed using an optical microscope. In FIG. 4, the presence of bubbles is observed above the side surface 5 of the element pattern.

[0070] In the measurement of the bubble diameter in a reflective array with a functional layer, the bubble diameter of the bubbles is determined by observing the entire circumference or cross-section of the element pattern at a magnification of 50 to 400 times using an optical microscope. Note that the magnification during the entire circumference observation can be set arbitrarily, and the magnification during the cross-section observation is set so that the upper and lower surfaces of the element pattern are simultaneously displayed on one screen. Here, when measuring the bubble diameter, only the bubbles that can be clearly observed as a whole from the observation image are targeted for measurement, and among the lengths of the line segments connecting two points on the contour line of the bubble, the longest line segment is measured as the diameter of the bubble. When actually measuring, the above-described detection of bubbles and measurement of the bubble diameter may be performed on randomly selected element patterns (for example, 100) on the reflective array.

[0071] (Suppression of bubbles) Next, a configuration for efficiently suppressing the generation of micro-fine bubble-sized bubbles will be described. FIG. 5 is a schematic cross-sectional view showing a part of the basic layer configuration of a reflective array including the side surface of element pattern 1. However, the following description is not limited to the layer configuration of FIG. 5, and it goes without saying that it is also applicable to other layer configurations as long as they do not deviate from the layer configuration shown in FIG. 3 and the object of the present invention.

[0072] In the layer configuration of FIG. 5, a ground layer 3 including a first surface and a second surface located on the opposite side of the first surface, a third surface facing the second surface, a dielectric layer 2 including a fourth surface located on the opposite side of the third surface, a fifth surface facing the fourth surface, a sixth surface located on the opposite side of the fifth surface, and an element pattern 1 including an element pattern side surface 5 (first side surface) located between the fifth surface and the sixth surface are provided. The first side surface includes a first end connected to the fifth surface, a second end connected to the sixth surface, and an intermediate point therebetween.

[0073] FIG. 6 is an enlarged schematic view near the first side surface of element pattern 1. The thickness L (μm) of element pattern 1 satisfies the following formula (1). 1.0 ≦ L (1) It is considered that the generation of microfibers with a bubble diameter of approximately 1 μm or more becomes a problem when the thickness L satisfies the formula (1). Therefore, according to the provisions of formula (1), a configuration specialized for suppressing microfibers can be achieved.

[0074] Also, it is defined that the angle (general inclination angle) α (°) between the straight line connecting the first end and the second end and the perpendicular line from the second end to the fifth surface satisfies the following formula (2). α≧10 (2) As a result, the side surface of the element pattern 1 has an overall configuration that spreads so as to be displaced outward from the upper surface (the sixth surface) to the lower surface (the fifth surface).

[0075] Next, the side surface of the element pattern 1 is divided at N points at equal intervals in the thickness direction using N obtained from the following formula (3), and the division point closest to the second end is defined as the first point, and the division point closest to the first end is defined as the Nth point. N = [L] (3) (N = 1, 2 ···) Here, N takes the value of the largest integer not exceeding L (μm).

[0076] And it is defined that the angle (point inclination angle) βi (°) between the straight line connecting the (i - 1)th point and the ith point and the perpendicular line from the second end to the lower surface satisfies the following formula (4) for any i (i = 1 to N + 1). βi≧0 (4) (i is an integer satisfying 1 ≦ i ≦ N + 1. However, the 0th point corresponds to the second end, and the (N + 1)th point corresponds to the first end.)

[0077] Figures 7A and 7B (hereinafter collectively referred to as Figure 7 for convenience) are schematic diagrams showing an example of the division of the side surface shape of the element pattern and the inclination angles α and βi. Figure 7(a) shows α when the formula (1) is not satisfied and N = 0 (La < 1.0). Regarding a thickness where La is less than 1.0 μm, even if the first side surface has an arbitrary shape, it is considered that there is almost no generation of bubbles with a microfiber size across the air layer as long as α≧10.

[0078] Figure 7(b) shows β1 when N = 1 (1.0 ≤ Lb < 2.0). If the conditions that the general inclination angle α ≥ 10 and the local inclination angles β1, β2 ≥ 0 are satisfied, even if the two divided sections of the first side surface have arbitrary shapes respectively, it is considered that there is almost no generation of micro-fabric size bubbles by catching an air layer.

[0079] Figure 7(c) shows β2 when N = 2 (2.0 ≤ Lc < 3.0). If the conditions that the general inclination angle α ≥ 10 and the local inclination angles β1 to β3 ≥ 0 are satisfied, even if the three divided sections of the first side surface have arbitrary shapes respectively, it is considered that there is almost no generation of micro-fabric size bubbles by catching an air layer.

[0080] Figure 7(d) shows β3 when N = 3 (3.0 ≤ Ld < 4.0). If the conditions that the general inclination angle α ≥ 10 and the local inclination angles β1 to β4 ≥ 0 are satisfied, even if the four divided sections of the first side surface have arbitrary shapes respectively, it is considered that there is almost no generation of micro-fabric size bubbles by catching an air layer.

[0081] Thus, when the thickness of the element pattern 1 satisfies Equation (1), in the divided sections scaled to approximately 1 μm size of N + 1 by Equation (3) according to the thickness, if the conditions of Equation (2) and Equation (4) are satisfied, even if the N + 1 divided sections of the first side surface have arbitrary shapes respectively, there is no depression that allows bubbles of a size larger than micro-fabric to enter, so it is possible to suppress the generation of bubbles. Therefore, the growth of a large number of bubbles with a bubble diameter of 100 μm or more can also be efficiently suppressed.

[0082] Examples and comparative examples will be described. Table 1 shows the specifications of the configuration of the reflect array used. Also, FIG. 8 is a graph showing the reflection angle and the reflection intensity (bistatic RCS) in the examples and the comparative examples. [Table 1]

[0083] (Example 1) For the basic configuration using copper with a thickness of 0.018 mm (L = 18 μm) for the element pattern and the ground layer, and a composite material of glass / fluororesin with a thickness of 0.764 mm for the dielectric, an additional functional layer with a thickness of 0.098 mm was laminated on the element pattern side to form a reflectarray. However, the conductivity of copper was 5.8×10^7 siemens / m, the real part of the relative permittivity of the dielectric was 2.6, tanδ was 0.0025, the real part of the relative permittivity of the additional functional layer was 2.70, and tanδ was 0.0060.

[0084] The operating frequency was set to 27.2 GHz, the target reflection characteristics were set to θi = 33° and θr = 0°, and the size Sx of the reflection control region in the x-axis direction was determined to be 20.238 mm using Equation (5). The number of divisions of the reflection control region was set to 3, and the sizes of the unit cell in the x-axis and y-axis directions were 6.746 mm. The shape of the element was a cross patch in which two square patches were orthogonal in the xy plane. Here, the element lengths of each element pattern in the reflection control region were the same, and only the element widths were different. The reflectarray was arranged with 81 unit cells in 9×9 in the x-axis and y-axis directions, and the size in the xy plane was 60.714 mm square.

[0085] With the general tilt angle α of all element patterns being 10° and the side surface shape being a plane with a uniform slope (the local tilt angles β1~β19 = 10°) (β1~β19 may be collectively referred to simply as β), an air layer with a thickness of 0.1 mm was provided on the side surface of the element pattern in 4 unit cells. The reflection characteristics when irradiating the reflectarray with a wave polarized parallel to the y-axis at θix = 33° and θiy = 0° were analyzed using HFSS.

[0086] Table 1 shows the reflection characteristics of the reflectarray in the xz plane. The radio wave incident at θi = 33° was reflected in the desired θr = 0° direction, and its RCS was 0.22 dBsm. Also, the relationship between the reflection angle and the reflection intensity is shown in Fig. 5.

[0087] (Example 2) In a reflect array similar to that of Example 1, with the general tilt angle α of all element patterns being 15° and the side surface shape being a flat surface with a uniform shape (local tilt angles β1 to β19 = 15°), an air layer of 0.1 mm was formed on the side surfaces of the element patterns in two unit cells. The reflection characteristics when irradiating the reflect array with a polarization parallel to the y-axis at θix = 33° and θiy = 0° were analyzed using HFSS.

[0088] The reflection characteristics of the reflect array in the xz plane are shown in Table 1. The radio wave incident at θi = 33° was reflected in the desired direction of θr = 0°, and its RCS was 0.23 dBsm. The relationship between the reflection angle and the reflection intensity is shown in Fig. 5.

[0089] (Example 3) In a reflect array similar to that of Example 1, with the general tilt angle α of all element patterns being 30° and the side surface shape being a flat surface with a uniform shape (local tilt angles β1 to β19 = 30°), an air layer of 0.1 mm was formed on the side surfaces of the element patterns in zero unit cells (no air bubbles). The reflection characteristics when irradiating the reflect array with a polarization parallel to the y-axis at θix = 33° and θiy = 0° were analyzed using HFSS.

[0090] The reflection characteristics of the reflect array in the xz plane are shown in Table 1. The radio wave incident at θi = 33° was reflected in the desired direction of θr = 0°, and its RCS was 0.25 dBsm. The relationship between the reflection angle and the reflection intensity is shown in Fig. 5.

[0091] (Comparative Example 1) In a reflect array similar to that of Example 1, with the general tilt angle α of all element patterns being 0° and the side surface shape being a flat surface, an air layer of 0.1 mm was formed on the side surfaces of the element patterns in 27 unit cells. The reflection characteristics when irradiating the reflect array with a polarization parallel to the y-axis at θix = 33° and θiy = 0° were analyzed using HFSS.

[0092] The reflection characteristics of the reflectarray in the xz plane are shown in Table 1. The radio wave incident at θi = 33° was reflected in the desired direction of θr = 0°, and its RCS was -1.2 dBsm. Also, the relationship between the reflection angle and the reflection intensity is shown in Fig. 5.

[0093] (Comparative Example 2) In a reflectarray similar to that of Example 1, with the general tilt angle α of all element patterns being 0° and the side surface shape being a uniform plane, an air layer of 0.1 mm was provided on the side surface of the element pattern in 27 unit cells. The reflection characteristics when irradiating the reflectarray with a polarization parallel to the y-axis at θix = 33° and θiy = 0° were analyzed using HFSS.

[0094] The reflection characteristics of the reflectarray in the xz plane are shown in Table 1. The radio wave incident at θi = 33° was reflected in the desired direction of θr = 0°, and its RCS was -1.18 dBsm. Also, the relationship between the reflection angle and the reflection intensity is shown in Fig. 5.

[0095] (Comparative Example 3) In a reflectarray similar to that of Example 1, with the general tilt angle α of all element patterns being 0° and the side surface shape being a uniform plane, an air layer of 0.1 mm was provided on the side surface of the element pattern in 8 unit cells. The reflection characteristics when irradiating the reflectarray with a polarization parallel to the y-axis at θix = 33° and θiy = 0° were analyzed using HFSS.

[0096] The reflection characteristics of the reflectarray in the xz plane are shown in Table 1. The radio wave incident at θi = 33° was reflected in the desired direction of θr = 0°, and its RCS was -1.06 dBsm. Also, the relationship between the reflection angle and the reflection intensity is shown in Fig. 5.

[0097] In Example 1, with an inclination angle α / β = 10°, 4 bubbles; in Example 2, with an inclination angle α / β = 15°, 2 bubbles; and in Example 3, with an inclination angle α / β = 30°, 0 bubbles were in a state of catching on the element pattern, and it was shown that good reflection intensity and suppression of unnecessary reflection were possible. On the other hand, in Comparative Examples 1 to 3, the inclination angle α / β = 0° in all cases. In Comparative Example 1, 27 bubbles; in Comparative Example 2, 27 bubbles; and in Comparative Example 3, 8 bubbles were in a state of catching on the element pattern, and unnecessary reflection to the back side of the reflector was observed. When the number of bubbles catching on the element pattern exceeds a certain number (4), the unnecessary reflection to the back side of the reflector increases, and the RCS in the direction of the desired reflection angle θr = 0° decreases. By providing an inclination angle at which the general inclination angle α and the local inclination angle βi on the side surface of the element pattern are displaced outward, it is considered possible to reduce the entry of bubbles between the additional functional layer and the side surface of the element pattern, and to realize the suppression of unnecessary reflection.

[0098] As described above, the embodiments of the present invention have been described. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

Explanation of Reference Numerals

[0099] 1... Element pattern, 2... Dielectric layer, 3... Ground layer, 4... Additional functional layer, 5... Side surface of element pattern

Claims

1. The device includes a ground layer, a dielectric layer, and an element pattern. Further, an additional functional layer is provided which covers at least the upper surface and the side surface of the element pattern, The thickness L (μm) of the element pattern satisfies the following formula (1), 1.0≦L (1) the side surface has a first end connected to a lower surface of the element pattern and a second end connected to the upper surface; An angle α (°) between a straight line connecting the first end and the second end in a cross section and a perpendicular line from the second end to the lower surface satisfies the following formula (2), α≧１０ （２） When the side surface is divided at N points at equal intervals in the thickness direction, using N calculated from the following formula (3), and the division point closest to the second end is defined as a first point, and the division point closest to the first end is defined as an Nth point, an angle βi between a line connecting the (i-1)th point and the i-th point in a cross section and a perpendicular line from the second end to the lower surface satisfies the following formula (4) for any i (i = 1 to N + 1), N = [L] (3) (N is an even number) β ≧ 0 (4) (i is an integer satisfying 1≦i≦N+1, where the 0th point corresponds to the second end, and the N+1th point corresponds to the first end.) Furthermore, each of the divided sections has an arbitrary shape (excluding a shape in which a straight line connecting the first end and a midpoint between the first end and the second end, and a straight line connecting the second end and the midpoint each have an angle of 0° or more with respect to a perpendicular line from the second end to the lower surface). The reflect array is characterized by:

2. The reflect array according to claim 1 , further comprising an adhesion improving layer.

3. The reflect array according to claim 1 , wherein the element pattern has a cross patch shape.

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