Reflectarray, electromagnetic wave reflection system, installation method for reflectarray, and reflectarray unit

Abstract

The purpose of the present invention is to provide: a reflectarray capable of reflecting, to a specific reflection angle, electromagnetic waves incident from a wide-angle range; an electromagnetic wave reflection system; and an installation method for the reflectarray.　To achieve the foregoing, this reflectarray is characterized in that: the reflectarray has a reflection control region for controlling a phase; the reflection control region satisfies an expression (1), where the longitudinal length of the reflection control region is designated as L, the wavelength of reflected electromagnetic waves as λ, the incident angle as θi, and the reflection angle as θr; the incident angle |θi| is in the range of 45° to 70°; the incident angle θi and the reflection angle θr satisfy the relationship of the following expression (2); and the incident allowable angle range Δθi is in the range of 5.5° to 16°.

Description

Reflectarray, electromagnetic wave reflection system, reflectarray installation method, and reflectarray unit

[0001] The present invention relates to a reflectarray, an electromagnetic wave reflecting system, a reflectarray installation method, and a reflectarray unit.

[0002] With the advancement of digitalization in society, data communication speeds in wireless communications have dramatically increased, and the accompanying increase in the frequency of electromagnetic waves (hereinafter also referred to as "radio waves"). However, as the frequency of electromagnetic waves increases, they tend to travel in a more directional manner, which makes it difficult for them to bend around shadows of buildings, etc., resulting in the creation of blind zones, areas where communication is not possible. 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, increasing the number of base stations requires a large amount of cost, making it difficult to rapidly increase the number of base stations. In recent years, technology that controls the direction of electromagnetic waves has been attracting attention as a solution to these issues.

[0003] Among these technologies, active development has been made on metamaterial or metasurface reflectors that can freely control the reflection angle of electromagnetic waves. Metamaterial reflectors include active reflectors that electrically control the direction of incident and reflected electromagnetic waves (e.g., Patent Document 1), and passive reflectors that do not have an electrical control mechanism and determine the direction of incident and reflected electromagnetic waves at the design stage, and then design the dimensions and material properties of the element based on that (e.g., Patent Document 2).

[0004] In Patent Document 1, a metamaterial structure is configured with a variable capacitor connected to the metamaterial structure, and the phase is controlled by the fixed capacitance of the metamaterial structure and the variable capacitance of the variable capacitor. The operation of the variable capacitor is controlled by a phase control signal (bias voltage). This makes it possible to reflect / scatter electromagnetic waves emitted from an electromagnetic wave source in any direction.

[0005] Furthermore, Patent Document 2 introduces a metasurface reflector that includes a metal ground plane provided on the bottom surface of a dielectric substrate that blocks polarization in all directions and multiple supercells with two or more types of cross-shaped metal resonators with different arm lengths. This metasurface reflector can control the phase by the structure of the metal resonators. The supercells with metal resonators are formed on the top surface of the dielectric substrate and are arranged with a diffraction grating period that reflects vertically and horizontally polarized incident waves and reflects extraordinary waves at a specified frequency with the required phase.

[0006] Patent Document 3 discloses a multibeam reflectarray that includes first and second array groups. The first array group includes a plurality of first element arrays, and the second array group includes a plurality of second element arrays, each of the first and second element arrays including a plurality of elements aligned in a predetermined direction. The phase difference between radio waves reflected by each of two of the plurality of elements is designed to be proportional to the product of the spacing between the two elements and the value of a trigonometric function for the reflection angle by the elements, so that the reflection angle when radio waves of a predetermined wavelength are reflected by the first array group differs from the reflection angle when radio waves of the predetermined wavelength are reflected by the second array group, thereby providing a multibeam reflectarray.

[0007] Patent Document 4 discloses a structure having a radio wave reflector. By providing a curvature to the reflecting surface and creating a structure in which the intensity of the reflected wave when the incident wave is specularly reflected is -30 dB or more compared to the incident wave, radio waves can be delivered over a wide range of space.

[0008] Patent Document 5 describes the development of an electromagnetic wave reflecting device that includes a panel with a reflective surface that reflects radio waves in a desired band selected from the 1 GHz to 170 GHz frequency band, and a support that supports the panel. The support is made up of a conductive frame and a slit that receives the edge of the panel, and the electromagnetic wave reflecting device, which is installed in the slit, improves radio wave propagation for mobile communications both indoors and outdoors.

[0009] Japanese Patent No. 6438857 Japanese Patent Publication No. 2021-48465 Japanese Patent No. 5480855 International Publication No. 2022 / 163813 International Publication No. 2022 / 196338

[0010] As the applications and communication spaces of wireless communication expand, there is a growing need to expand the space in which metamaterial reflectors can effectively incident or reflect electromagnetic waves. Furthermore, it is desirable that such metamaterial reflectors be manufactured more inexpensively and with higher yields. However, the following problems remain. (Example 1) The active reflector described in Patent Document 1 can control the angle between the incident and reflected electromagnetic waves by changing the voltage, etc., allowing for appropriate angle adjustment depending on the angle between the transmitter and receiver, providing a high degree of practical flexibility. However, it requires a phase control signal to control the phase, which increases its cost. The passive reflector described in Patent Document 2 can be manufactured inexpensively because it does not have an electrical control mechanism. However, it has a problem of limited practical flexibility because the angle between the incident and reflected electromagnetic waves is fixed.

[0011] (Example 2) Because metal reflectors are specular, there are limitations to the installation location when reflecting radio waves from a base station and delivering them to dead zones (areas where communication is not possible). In contrast, a normal reflectarray (metasurface reflector) can be made to reflect radio waves in a direction different from specular reflection (asymmetric reflection) by adjusting the element pattern, allowing for flexibility in the installation location and angle when delivering radio waves to dead zones.

[0012] However, although it is possible to increase the reflection intensity by connecting reflectarrays (metasurface reflectors) and increasing their area, the directivity of the reflected waves increases and the reflection area becomes narrower, which causes the problem that radio waves cannot be delivered over a wide area to blind zones. Patent Documents 2, 4, and 5 do not even disclose any recognition of this issue.

[0013] Furthermore, in reflectarrays with element patterns, if dimensional errors occur in the element patterns, the reflection phase in each region tends to vary significantly from the design value, which can reduce the reflection intensity in the desired direction. Furthermore, if multiple array groups are used, the design becomes complicated and can lead to a decrease in the yield rate during manufacturing. Patent Document 3 discloses the use of two types of reflectors with different reflection angles to address the issue of narrowing the beam area, but this complicates the design and poses a risk of a decrease in the yield rate.

[0014] Therefore, an object of the present invention is to provide a technology that enables easy communication over a wider area, even in blind areas, using a reflectarray. For example, it is desirable to provide a reflectarray, an electromagnetic wave reflection system, and a reflectarray installation method that are passive reflectors that can be manufactured inexpensively and that can reflect electromagnetic waves incident from a wide range of angles to a predetermined angle. It is also desirable to provide a reflectarray unit that can freely design the reflection angle, can deliver radio waves over a wide range of space (wider coverage), and has a high yield rate.

[0015] To solve the above problems, one representative embodiment of the present invention is a single or multiple reflectarrays including an element pattern, a dielectric layer, and a ground layer, and having a wide range of incident or reflection angles of electromagnetic waves for good communication. The reflectarray further includes a reflection control region for controlling the phase, where the reflection control region satisfies Equation (1) (described below), where L is the length of the long side, λ is the wavelength of the reflected electromagnetic wave, θi is the incident angle, and θr is the reflection angle. The incident angle |θi| is in the range of 45° to 70°, and the incident angle θi and the reflection angle θr satisfy the relationship of Equation (2) (described below), and the allowable incident angle range Δθi is in the range of 5.5° to 16°. The multiple arranged reflectarrays (hereinafter referred to as "reflectarray units") are further characterized in that a unit space exists between the reflectarrays, each reflectarray includes at least one reflection control region, and the reflection control region is the same for all of the reflectarrays.

[0016] According to the present invention, a reflectarray can be used to easily perform communication over a wider area, even in blind zones. For example, a reflectarray can be provided that can reflect electromagnetic waves incident from a wide angular range at a predetermined angle. Furthermore, for example, a reflectarray unit can be provided that can freely design the reflection angle, can deliver radio waves over a wide range of space (wider coverage), and has a high yield rate. Problems, configurations, and effects other than those described above will be made clear by the description of the following embodiments of the invention.

[0017] FIG. 1 is a diagram showing the angle of incidence and the angle of reflection when a reflectarray is arranged on the xy plane. FIG. 2 is a plan view showing the configuration of the reflectarray. FIG. 3 is a perspective view showing the configuration of the reflectarray 20. FIG. 4 is a diagram showing an example of the layer configuration of the reflectarray 20. FIG. 5 is a diagram showing an example of the layer configuration of the reflectarray 20. FIG. 6 is a diagram showing an example of the arrangement of unit cells depending on the direction in which asymmetric reflection is to be generated. FIG. 7 is a diagram showing an example of the arrangement of unit cells depending on the direction in which asymmetric reflection is to be generated. FIG. 8 is a diagram showing an example of the arrangement of unit cells depending on the direction in which asymmetric reflection is to be generated. FIG. 9 is a diagram showing the configuration of an element pattern. FIG. 10 is a diagram showing an example of the shape of an element pattern after etching. FIG. 11 is a diagram showing an example of an electromagnetic wave reflection system using a reflectarray. FIG. 12 is a diagram showing an example of a reflectarray installed on a support. FIG. 13 is an analysis result of the reflectarray 20 obtained in Example A1. FIG. 14 is an analysis result of the reflectarray 20 obtained in Comparative Example A1. FIG. 15 shows a comparison of the amount of power change that can be received at a specific reflection angle θrx when the angle of incidence is changed in Example A1 and Comparative Example A1. FIG. 16 shows the analysis result of the reflectarray 20 obtained in Example A2. FIG. 17 shows the analysis result of the reflectarray 20 obtained in Comparative Example A2. FIG. 18 shows a comparison of the amount of power change that can be received at a specific reflection angle θrx when the angle of incidence is changed in Example A2 and Comparative Example A2. FIG. 19 shows the analysis result of the reflectarray 20 obtained in Example A3. FIG. 20 shows the analysis result of the reflectarray 20 obtained in Comparative Example A3. FIG. 21 shows a comparison of the amount of power change that can be received at a specific reflection angle θrx when the angle of incidence is changed in Example A3 and Comparative Example A3. FIG. 22 shows the analysis result of the reflectarray 20 obtained in Example A4. FIG. 23 shows the analysis result of the reflectarray 20 obtained in Comparative Example A4. FIG. 24 shows the results of comparing the amount of change in power that can be received at a specific reflection angle θrx when the incident angle is changed in each of Example A4 and Comparative Example A4.FIG. 25 is a diagram showing the relationship between the absolute value of the incident angle and the acceptable incident angle range in Examples A1-A4, and the relationship between the absolute value of the reflection angle and the acceptable incident angle range in Comparative Examples A1-A4. FIG. 26 is an analysis result of the reflectarray 20 obtained in Example A5. FIG. 27 is an analysis result of the reflectarray 20 obtained in Comparative Example A5. FIG. 28 is a comparison result of the amount of power change that can be received at a specific reflection angle θrx when the incident angle is changed in Example A5 and Comparative Example A5. FIG. 29 is an analysis result of the reflectarray 20 obtained in Example A6. FIG. 30 is an analysis result of the reflectarray 20 obtained in Comparative Example A6. FIG. 31 is a comparison result of the amount of power change that can be received at a specific reflection angle θrx when the incident angle is changed in Example A6 and Comparative Example A6. FIG. 32 is an analysis result of the reflectarray 20 obtained in Example A7. FIG. 33 is an analysis result of the reflectarray 20 obtained in Comparative Example A7. FIG. 34 shows a comparison of the amount of power change that can be received at a specific reflection angle θrx when the angle of incidence is changed in Example A7 and Comparative Example A7. FIG. 35 shows the analysis results of the reflectarray 20 obtained in Example A8. FIG. 36 shows the analysis results of the reflectarray 20 obtained in Comparative Example A8. FIG. 37 shows the comparison of the amount of power change that can be received at a specific reflection angle θrx when the angle of incidence is changed in Example A8 and Comparative Example A8. FIG. 38 is a plan view showing an example of the configuration of a reflectarray unit 30 according to embodiment B-1. FIG. 39 is a cross-sectional view showing an example of the configuration of a reflectarray unit 30 according to embodiment B-1. FIG. 40 is a plan view showing an example of the configuration of a reflectarray unit 30 according to embodiment B-2. FIG. 41 is a cross-sectional view showing an example of the configuration of a reflectarray unit 30 according to embodiment B-2. FIG. 42 is a schematic diagram showing an example of installation of a reflectarray in the prior art. FIG. 43 is a schematic diagram showing an example of installation of a reflectarray in an embodiment of the present invention. Fig. 44 is a diagram showing a plan view and reflection characteristics of a unit reflectarray according to Comparative Example B1, and Fig. 45 is a diagram showing a plan view and reflection characteristics of a reflectarray according to Comparative Example B2.FIG. 46 is a diagram showing a plan view and reflection characteristics of a reflect array unit according to Comparative Example B3. FIG. 47 is a diagram showing a plan view and reflection characteristics of a reflect array unit according to Example B1. FIG. 48 is a diagram showing a plan view and reflection characteristics of a reflect array unit according to Example B2. FIG. 49 is a diagram showing a plan view and reflection characteristics of a reflect array unit according to Example B3. FIG. 50 is a diagram showing a plan view and reflection characteristics of a reflect array unit according to Example B4. FIG. 51 is a diagram showing a plan view and reflection characteristics of a reflect array unit according to Example B5. FIG. 52 is a diagram showing a plan view and reflection characteristics of a reflect array unit according to Example B6. FIG. 53 is a diagram showing a plan view and reflection characteristics of a reflect array unit according to Example B7. FIG. 54 is a diagram showing a plan view and reflection characteristics of a reflect array unit according to Example B8. FIG. 55 is a diagram showing a plan view and reflection characteristics of a reflect array unit according to Example B9. FIG. 56 is a diagram showing a plan view and reflection characteristics of a reflect array unit according to Example B10. Fig. 57 is a diagram showing a plan view and reflection characteristics of a reflect array unit according to Example B11. Fig. 58 is a diagram showing a plan view and reflection characteristics of a reflect array unit according to Example B12. Fig. 59 is a diagram showing a plan view, a cross-sectional view, and reflection characteristics of a reflect array unit according to Example B13. Fig. 60 is a diagram showing a plan view, a cross-sectional view, and reflection characteristics of a reflect array unit according to Example B14. Fig. 61 is a diagram showing a plan view, a cross-sectional view, and reflection characteristics of a reflect array unit according to Example B15. Fig. 62 is a diagram showing a plan view, a cross-sectional view, and reflection characteristics of a reflect array unit according to Example B16.

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to these embodiments. In addition, in the description of the drawings, identical parts are denoted by the same reference numerals. When there are multiple components having the same or similar functions, they may be described by using the same reference numerals with different subscripts. Furthermore, when it is not necessary to distinguish between these multiple components, the subscripts may be omitted. The position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc., in order to facilitate understanding of the invention. Therefore, the present disclosure is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

[0019] (Explanation of Terms) In this disclosure, a "reflectarray (electromagnetic wave reflector)" is a component that reflects electromagnetic waves and has one or more reflection control regions that control the phase, and is a reflector that does not perform phase control using external power. It includes reflectors that perform asymmetric reflection where the angle of incidence and the angle of reflection differ, reflectors that scatter electromagnetic waves in multiple directions, and reflectors that concentrate electromagnetic waves at a specific location. Phase control using external power refers to an active reflector that has an external power source and can control the phase by controlling the voltage, etc.

[0020] A "reflection control area" refers to a part of the area that constitutes the reflectarray. A reflection control area is the smallest area that can reflect electromagnetic waves incident on that area in a specified direction. A reflectarray is composed of a combination of one or more reflection control areas. The reflection control area includes not only a two-dimensional area in which the electromagnetic waves are incident in a direction parallel to the area, but also a layer structure formed in a direction perpendicular to the area.

[0021] A "unit cell" refers to an area obtained by dividing the reflection control area. One unit cell includes one element pattern (element). Two or more unit cells exist in one reflection control area.

[0022] In the following description, an xyz coordinate system is applied, and a reflectarray is placed on an xy plane (sometimes simply referred to as a "plane"). The positive direction of the z axis is sometimes referred to as upward, and the negative direction as downward. A view when the xy plane is viewed from above the z axis (planar view) is called a plan view, and a view when a plane cut by a plane parallel to the z axis is viewed from a perpendicular direction (cross-section) is called a cross-sectional view. FIG. 1 is a diagram showing the angle of incidence and the angle of reflection when a reflectarray is placed on an xy plane. The terminology related to the definition of angles in this disclosure will be explained with reference to FIG. 1. "θi" indicates the angle of incidence of an incident wave. The angle of incidence in the x-axis direction is defined as θix, and the angle of incidence in the y-axis direction is defined as θiy. Furthermore, "θr" indicates the angle of reflection of a reflected wave. The angle of reflection in the x-axis direction is defined as θrx, and the angle of reflection in the y-axis direction is defined as θry. The angle θx in the x-axis direction is expressed as a positive angle (0° to 180°) when it extends from the positive z-axis direction toward the positive x-axis direction, and as a negative angle (0° to -180°) when it extends from the positive z-axis direction toward the negative x-axis direction. Similarly, the angle θy in the y-axis direction is expressed as a positive angle (0° to 180°) when it extends from the positive z-axis direction toward the positive y-axis direction, and as a negative angle (0° to -180°) when it extends from the positive z-axis direction toward the negative y-axis direction.

[0023] 2 is a plan view showing the configuration of a reflectarray. The reflectarray 20 is composed of one or more reflection control regions 5 formed by periodically arranging a plurality of element patterns 1 on a plane, and can set the direction of asymmetric reflection to a desired value (asymmetric reflection set to a desired value is also called "reference asymmetric reflection"). The reflectarray 20 includes at least element patterns (elements) 1, a dielectric layer 2, and a ground layer (base plate) 3.

[0024] Next, the configuration of the reflectarray 20 will be described in more detail with reference to Fig. 3. Fig. 3 is a perspective view showing the configuration of the reflectarray 20. The reflectarray 20 generates a predetermined asymmetric reflection of electromagnetic waves along the x-axis. The reflectarray 20 has a configuration in which a plurality of reflection control regions identical to the reflection control region 5 are arranged in the x-axis and y-axis directions. In Fig. 3, the reflection control region 5 is shown by a solid line as a representative of the reflection control regions included in the reflectarray 20. The reflection control region 5 has a plurality of unit cells 4. １ , 4 ２ , 4 ３ , …4 ｎ (Hereinafter, when a unit cell is referred to without specifying it, it will also be referred to as a "unit cell 4", where n is a positive integer of 2 or more.) The unit cells 4 are portions obtained by dividing the reflection control area 5 at equal intervals along the x-axis direction. n is the number of divisions when dividing the reflection control area into unit cells in the x-axis direction. The unit cells 4 are square, and if the size (length) of the unit cell 4 in the x-axis direction is sx and the size in the y-axis direction is sy, and the size (long side) of the reflection control area 5 in the x-axis direction is Lx and the size in the y-axis direction is Ly, then sx = Lx / n and sy = Ly.

[0025] Furthermore, the size of the reflectarray 20 is determined by the size and number of reflection control areas 5. For example, if a reflectarray that provides asymmetric reflection in the x-axis direction has eight reflection control areas 5 arranged in the x-axis direction and six in the y-axis direction, the size of the reflectarray 20 in the x-axis direction is 8Lx and the size in the y-axis direction is 6Ly. The reflection pattern of the reflectarray 20 changes depending on the number of reflection control areas arranged in the direction of asymmetric reflection. That is, in FIG. 3 , the reflection pattern changes depending on the number of reflection control areas arranged in the x-axis direction, but the number of reflection control areas arranged in the y-axis direction does not affect the reflection pattern. The more reflection control areas arranged in the x-axis direction, the thinner the reflection pattern of the reflectarray. The number of reflection control areas arranged in the y-axis direction affects the reflection intensity, and the greater the number of reflection control areas arranged in the y-axis direction, the greater the reflection intensity.

[0026] 2, reflection control region 5 is configured by n unit cells 4 aligned in the x-axis direction, and reflect array 20 is shown to include a plurality of reflection control regions 5, but the present disclosure is not limited to such a configuration. The reflection control region may be configured by unit cells aligned in the y-axis, or may include unit cells aligned in the x-axis and y-axis. The configuration of the reflection control region will be described later.

[0027] (Configuration of Element Pattern) An element pattern is formed on the surface of the unit cell 4 facing the +z-axis direction. １ , unit cell 4 ２ , ...unit cell 4 ｎ Unit cell 4 １ Element pattern 1 １ is formed. Unit cell 4 ２ Element pattern 1 ２ is formed. Unit cell 4 ３ Element pattern 1 ３ is formed. Unit cell 4 ｎ Element pattern 1 ｎ Furthermore, the element patterns are arranged at equal intervals within the reflection control region and between adjacent regions of the same reflection control region. Specifically, for each element pattern within the reflection control region 5, if the size of the closest interval between adjacent element patterns in the x-axis direction (hereinafter also referred to as "gap") is gx, then within the reflection control region 5, １ From 1 ｎare arranged at equal intervals gx. Furthermore, when the gap between element pattern 1n in reflection control region 5 and element pattern 1x1 in reflection control region 5x (shown by a dashed line, including unit cell 4x1 in which element pattern 1x1 is formed, unit cell 4x2 in which element pattern 1x2 is formed, ... unit cell 4xn in which element pattern 1xn is formed) adjacent to reflection control region 5 in the x-axis direction is defined as Gx, Gx and gx are equal in Fig. 3. Note that the gap between the element pattern in reflection control region 5 and the element pattern in reflection control region 5y (shown by a dashed line, including unit cell 4y1 in which element pattern 1y1 is formed, unit cell 4y2 in which element pattern 1y2 is formed, ... unit cell 4yn in which element pattern 1yn is formed) adjacent to reflection control region 5 in the y-axis direction is uniform and shown as Gy in Fig. 3.

[0028] Within the reflection control region, each element pattern has a shape that is slightly different from the other element patterns. １ From element pattern 1 ｎ The shape of the element pattern shown in is sometimes called a cross patch. A cross patch is a shape in which two square patches intersect at right angles on the xy plane. Element pattern 1 １ The element pattern 1 has a square patch having an element length lx1 in the x-axis direction and an element width wy1 in the y-axis direction, and a square patch having an element length ly1 in the y-axis direction and an element width wx1 in the x-axis direction, which are orthogonal to each other with a common center of gravity. ｎ has a shape in which a square patch having an element length lxn and an element width wyn and a square patch having an element length lyn and an element width wxn are orthogonal to each other with a common center of gravity.

[0029] (Explanation of Each Component and Design Method) (Layer Configuration) The layer configuration of the reflectarray 20 will be described with reference to FIGS. 4 and 5. FIGS. 4 and 5 are diagrams showing an example of the layer configuration of the reflectarray 20. The reflectarray 20 has a configuration in which at least an element pattern 1, a dielectric layer 2, and a ground layer 3 are stacked in a direction from the +z-axis direction to the −z-axis direction. In the following description, a configuration consisting of three layers, namely, the element pattern 1, the dielectric layer 2, and the ground layer 3, is referred to as the “basic configuration.” In practice, the reflectarray 20 preferably has one or more layers having various functionalities (hereinafter also referred to as “functional layers”) stacked on either the element pattern 1 side or the ground layer 3 side of the basic configuration, or on both sides. In the following description, layers included in the reflectarray other than the element pattern 1, the dielectric layer 2, and the ground layer 3 may be referred to as “functional layers” when the type of layer is not specified.

[0030] If necessary, a layer for improving the adhesion between the element pattern 1 and the dielectric layer 2, or between the ground layer 3 and the dielectric layer 2, may be formed. A layer used for a purpose other than improving the adhesion may also be formed. Note that intermediate products generated in the manufacturing process of the reflect array 20 may be formed in layers and remain on the reflect array 20.

[0031] Examples of functional layers include a design layer that is designed to take into consideration the landscape of the location where the reflect array 20 is installed, an installation layer that allows the reflect array 20 to be easily installed on a support such as a wall or ceiling, a protective layer that protects the basic structure, and an adhesive layer for laminating each layer.

[0032] FIG. 4 is a diagram showing an example of the arrangement of the functional layer 7. The lamination method on the element pattern 1 side may be such that the functional layer 7 is laminated so as to fill the gaps between the plurality of element patterns 1 as in the reflect array 20a ( FIG. 4( a) ), or such that the functional layer 7 is laminated so as to contact the upper surface of the element pattern 1 while maintaining the gaps between the plurality of element patterns 1 as in the reflect array 20b ( FIG. 4( b) ), or such that the functional layer 7 is laminated so as not to contact the upper surface of the element pattern 1 as in the reflect array 20c ( FIG. 4( c) ). Note that when the reflect arrays 20a to 20c have a common configuration except for the functional layer 7, the reflect arrays 20a to 20c each have different reflection characteristics. Therefore, it is possible to change the characteristics of the reflect array by changing the lamination method of the functional layer 7.

[0033] Figure 5 is a diagram showing another example of the arrangement of functional layers. Figure 5 shows an example of the arrangement of functional layers, including a protective layer 8, an adhesive layer 9, a design layer 10, and an installation layer 11. Figure 5(a) shows a reflectarray 20d in which a protective layer 8 is laminated to cover the element pattern 1 and the ground layer 3, and further includes a design layer 10 on the element pattern 1 side via an adhesive layer 9, and an installation layer 11 on the ground layer side via an adhesive layer 9. Figure 5(b) shows a reflectarray 20e in which an installation layer 11 is on the ground layer side via an adhesive layer 9, and a design layer 10 is on the element pattern 1 side separated by an air gap.

[0034] (Reflection Control Region) The reflectarray 20 includes at least one reflection control region. The properties of the reflectarray can be changed by changing the arrangement of the reflection control regions. For example, when electromagnetic waves of a certain wavelength are incident at a certain incident angle, it is possible to impart the reflectarray with the property of reflecting in a single direction by periodically arranging reflection control regions with a common reflection direction. Furthermore, when electromagnetic waves of a certain wavelength are incident at a certain incident angle, it is possible to impart the reflectarray with the property of scattering the electromagnetic waves in multiple directions by configuring a reflectarray with reflection control regions each with a different reflection direction. Furthermore, it is also possible to impart the property of concentrating electromagnetic waves at a specific location by shifting the reflection direction for each reflection control region by a predetermined angle. The frequency expected to be applied to the reflectarray during design is hereinafter referred to as the "operating frequency."

[0035] The size Lx of the reflection control area in the x-axis direction is determined, for example, by equation (3), where λ is the wavelength of the operating frequency, θix is ​​the x-axis component of the angle of incidence of the electromagnetic wave incident on the reflection control area, and θrx is the x-axis component of the angle of reflection of the electromagnetic wave reflected from the reflection control area. When θix ≠ −θrx,

[0036] Furthermore, the size Ly of the reflection control area in the y-axis direction is determined, for example, by equation (4), where θiy is the y-axis component of the angle of incidence of the electromagnetic wave incident on the reflection control area, and θry is the y-axis component of the angle of reflection of the electromagnetic wave reflected from the reflection control area. When θiy≠−θry,

[0037] In particular, when there is no distinction between the x and y axis components of equations (3) and (4), they are expressed as equation (1).

[0038] (Relationship Between Unit Cell and Reflection Phase) The relationship between the unit cell and the reflection phase will be described with reference to FIGS. 6 to 8. FIGS. 6 to 8 are diagrams showing examples of arrangements of unit cells according to the direction in which asymmetric reflection is generated. The reflection control region 5 has at least two unit cells. Here, FIG. 6(a) shows the direction of an electromagnetic wave (incident wave) incident on the reflectarray 20f and the direction of an electromagnetic wave (reflected wave) reflected from the reflectarray 20f. In other words, the thick solid arrows indicate the traveling direction of the wavefront, the arrow pointing toward the reflectarray 20 indicates the traveling direction of the wavefront of the incident wave, and the arrow pointing away from the reflectarray 20f indicates the traveling direction of the wavefront of the reflected wave. FIG. 6(b) shows a plan view of the reflectarray 20f as seen from the z-axis direction. The relationships between (a) and (b) in FIGS. 7 and 8 are similar to those between (a) and (b) in FIG. 6.

[0039] The unit cells have the effect of reflecting incident electromagnetic waves with a predetermined phase difference. Because each unit cell in the reflection control region exhibits a different reflection phase, the wavefront of the reflected wave generated in the reflection control region is tilted from the reflection angle when the angle of incidence and the angle of reflection are equal, resulting in asymmetric reflection, which is different from symmetric reflection, where the angle of incidence and the angle of reflection are equal.

[0040] When reflectarray 20f is intended to perform asymmetric reflection only along the x-axis direction (θix ≠ -θrx as shown in Figure 6(a)), unit cells exhibiting different reflection phases along the x-axis direction are arranged in reflection control region 5a (Figure 6(b)). Reflection control region 5a has three divisions, n = 3, and has three unit cells arranged in the x-axis direction. The size (long side) Lx of reflection control region 5a in the x-axis direction is determined by equation (3), and the size of the unit cell in the x-axis direction is Lx / 3. When the y-axis component of the reflection angle is symmetric reflection (θiy = -θry), as represented by this example, Ly does not need to be determined by equation (4) and can take any value. However, for ease of design, a square unit cell whose size is determined by Lx and the division number n is used for convenience, and Ly is set equal to Lx / 3.

[0041] Similarly, when reflectarray 20g is intended to perform asymmetric reflection only along the y-axis direction (θiy ≠ −θry as shown in FIG. 7A ), unit cells exhibiting different reflection phases are arranged along the y-axis direction in reflection control region 5b ( FIG. 7B ). Here, m (m is a positive integer greater than or equal to 2) is the number of divisions when dividing the reflection control region into unit cells in the y-axis direction. Reflection control region 5b has three divisions, m = 3, and has three unit cells arranged in the y-axis direction. The size Ly of reflection control region 5b in the y-axis direction is determined by equation (4), and the size of the unit cell in the y-axis direction is Ly / 3. Because the x-axis component of the reflection angle is symmetric reflection, Lx does not need to be determined by equation (3) and can take any value. However, for ease of design, a square unit cell whose size is determined by Ly and the number of divisions m is used for convenience, and Lx is set equal to Ly / 3.

[0042] FIG. 8(a) shows the relationship between the reflectarray and electromagnetic waves, with FIG. 8(a1) showing the electromagnetic waves projected onto the zx plane and FIG. 8(a2) showing the electromagnetic waves projected onto the zy plane. When reflectarray 20h is intended to perform asymmetric reflection in both the x-axis and y-axis directions (θix≠-θrx as shown in FIG. 8(a1) and θiy≠-θry as shown in FIG. 8(a2)), unit cells with different reflection phases are arranged in reflection control region 5c in the x-axis direction, and unit cells with different reflection phases are also arranged in the y-axis direction (FIG. 8(b)). Reflection control region 5c includes nine unit cells, with three unit cells arranged in the x-axis direction and three unit cells arranged in the y-axis direction. The number of divisions in reflection control region 5c can also be expressed as 3 × 3 = 9, using the number of divisions in the x-axis direction (n = 3) and the number of divisions in the y-axis direction (m = 3). The size Lx of reflection control region 5c in the x-axis direction is determined by equation (3), and the size Ly of reflection control region 5c in the y-axis direction is determined by equation (4). The size of the unit cell in the x-axis direction is determined by Lx and n and is equal to Lx / 3. The size of the unit cell in the y-axis direction is determined by Ly and m and is equal to Ly / 3. Both the x-axis and y-axis components of the incident wave are reflected asymmetrically. Therefore, the x-axis component of the reflected wavefront differs from the x-axis component of the incident wavefront, and the y-axis component of the reflected wavefront differs from the y-axis component of the incident wavefront ( FIG. 8( a) ). Note that gx denotes the gap between element patterns in reflection control region 5c in the x-axis direction. gy denotes the gap between element patterns in reflection control region 5c in the y-axis direction. The spacing gx between element patterns in the x-axis direction is equal, and the spacing gy between element patterns in the y-axis direction is equal. Although gx and gy are shown as being different, they may be equal. Gx indicates the gap between the element pattern of reflection control region 5c and the element pattern of the reflection control region adjacent to reflection control region 5c in the x-axis direction. Gy indicates the gap between the element pattern of reflection control region 5c and the element pattern of the reflection control region adjacent to reflection control region 5c in the y-axis direction.When reflection control area 5c is adjacent to reflection control area 5c in the y-axis direction (or x-axis direction) without changing its position in the x-axis direction (or y-axis direction), gx and Gx are equal, and gy and Gy are equal.

[0043] (Distribution of Reflection Phase and Distribution of Surface Impedance Within Reflection Control Region) The distribution of reflection phase within the reflection control region is determined, for example, according to equations (5) and (6). Here, the wavelength of the operating frequency is λ (m), the x-axis component of the incident angle of the electromagnetic wave incident on the reflection control region is θix, the y-axis component is θiy, the x-axis component of the reflection angle of the electromagnetic wave reflected from the reflection control region is θrx, and the y-axis component is θry. The reflection phases at arbitrary coordinates x1 and x2 parallel to the x-axis within the reflection control region are respectively φx1 and φx2, the distance between coordinates x1 and x2 is dx, and the reflection phase difference between coordinates Φx1 and Φx2 is ΔΦx. Furthermore, the reflection phases at arbitrary coordinates y1 and y2 parallel to the y-axis are respectively φy1 and φy2, the distance between coordinates y1 and y2 is dy, and the reflection phase difference between Φy1 and Φy2 is ΔΦy. When the reflection control region is intended to provide asymmetric reflection along the x-axis direction, it is preferable that formula (5) be satisfied, and when the reflection control region is intended to provide asymmetric reflection along the y-axis direction, it is preferable that formula (6) be satisfied. Furthermore, when the reflection control region is intended to provide asymmetric reflection in both the x-axis direction and the y-axis direction, it is preferable that both formulas (5) and (6) be satisfied.

[0044] Alternatively, instead of the reflection phase, the distribution of surface impedance can be applied to the reflection control area. In this case, the distribution of surface impedance can be expressed by, for example, equations (7) and (8). Here, Zsx is the surface impedance distribution parallel to the x-axis direction of the reflection control area, Zsy is the surface impedance distribution parallel to the y-axis direction of the reflection control area, and η １is the impedance of the incident wave. Furthermore, the x-axis component of the incident angle of the electromagnetic wave incident on the reflection control area is θix, the y-axis component is θiy, the x-axis component of the reflection angle of the electromagnetic wave reflected from the reflection control area is θrx, and the y-axis component is θry. Note that x1 and x2 indicate x coordinates as relative coordinates within the reflection control area, and can take the reference x=0 at any coordinate in the reflection control area. Similarly, y1 and y2 indicate y coordinates as relative coordinates within the reflection control area, and can take the reference y=0 at any coordinate in the reflection control area. Furthermore, k １ is the wave number of the reflected wave. j represents the imaginary unit. When the reflection control region is intended to perform asymmetric reflection along the x-axis direction, it is preferable that formula (7) be satisfied, and when the reflection control region is intended to perform asymmetric reflection along the y-axis direction, it is preferable that formula (8) be satisfied. Furthermore, when the reflection control region is intended to perform asymmetric reflection in both the x-axis direction and the y-axis direction, it is preferable that both formulas (5) and (6) be satisfied.

[0045] Other surface impedance distributions are expressed by, for example, equations (9) and (10). When the reflection control region is intended to cause asymmetric reflection only along the x-axis direction, it is preferable that equation (9) be satisfied, and when the reflection control region is intended to cause asymmetric reflection only along the y-axis direction, it is preferable that equation (10) be satisfied. Furthermore, when the reflection control region is intended to cause asymmetric reflection in both the x-axis and y-axis directions, it is preferable that equations (9) and (10) be satisfied simultaneously.

[0046] The above-mentioned formulas (5) to (10) are examples of design formulas used when designing the distribution of the reflection phase and the distribution of the surface impedance. The present disclosure is not limited to the use of formulas (5) to (10), and other design formulas can be selected as appropriate.

[0047] (Method for designing a reflectarray) A method for designing a reflectarray will now be described. As an example, a method for designing a reflectarray in which a plurality of identical reflection control regions are arranged in the x-axis direction will be described here. A similar method can also be used to design a reflectarray in which a plurality of identical reflection control regions are arranged in the y-axis direction, or a reflectarray that is intended to provide asymmetric reflection in both the x-axis direction and the y-axis direction.

[0048] (Design Method 1) Design Method 1 controls the phase of the element pattern by changing the element width while fixing the element length and the gap between the element patterns. This method has the advantage that the phase change associated with changes in element width is more gradual than design methods 2 and 3 described below, making it easier to ensure product performance even if changes occur in the element shape during the manufacturing process. (Step 1) First, the target reflection characteristics (operating frequency, incident angle, and reflection angle) are set. (Step 2) Next, the size Lx of the reflection control region is determined using equation (3). (Step 3) Next, the size Lx of the reflection control region is divided into n parts. The size of the unit cell is determined. (Step 4) Next, the element length lx of the element pattern is determined within the unit cell. Since the element patterns are evenly and uniformly arranged within the unit cell, the gap gx between the element patterns is also determined. (Step 5) Next, the reflection phase of the unit cell is analyzed using the element width wx as a design parameter. The reflection phase is derived using the element width wx of the element pattern as a design parameter, and analysis results are obtained that show the relationship between the element width and reflection phase in the unit cell. (Step 6) Next, the ideal reflection phase or impedance for achieving the reflection characteristics of the target reflection control region is calculated using equations (5) to (10), and the element width wx that achieves the desired reflection phase or impedance is selected based on the above analysis results. (Step 7) Next, a reflectarray is formed so as to include at least one reflection control region. The reflection characteristics of the reflectarray are analyzed. (Step 8) Note that, based on the analysis results of step 7, it is also possible to further fine-tune the element width wx using an optimization method to further increase the RCS at the target reflection angle and reduce the RCS at angles other than the target angle.

[0049] (Design Method 2) Design Method 2 is a design method in which the phase of the element pattern is controlled by fixing the element width and varying the element length. (Step 1) First, the target reflection characteristics (operating frequency, incident angle, and reflection angle) are set. (Step 2) Next, the size Lx of the reflection control region is determined using Equation (3). (Step 3) Next, the size Lx of the reflection control region is divided into n parts. The size of the unit cell is determined. (Step 4) Next, the element width wx of the element pattern is determined within the range that fits into the unit cell. (Step 5) Next, the reflection phase of the unit cell is analyzed using the element length lx as a design parameter. The reflection phase is derived using the element length lx of the element pattern as a design parameter, and analysis results showing the relationship between the element length and reflection phase in the unit cell are obtained. (Step 6) Next, the ideal reflection phase or impedance to achieve the target reflection characteristics of the reflection control region is calculated using Equations (5) to (10), and the element length lx that achieves the desired reflection phase or impedance is selected based on the above analysis results. (Step 7) Next, a reflectarray is formed so as to include at least one reflection control region. The reflection characteristics of the reflectarray are analyzed. (Step 8) Note that, based on the analysis results of Step 7, it is also possible to further fine-tune the element length lx using an optimization method so as to further increase the RCS at the target reflection angle and reduce the RCS at angles other than the target angle.

[0050] (Design Method 3) Design Method 3 is a design method in which the phase of the element pattern is controlled by changing both the element width and element length. This design method is effective when design methods 1 and 2 do not ensure a sufficient reflection phase change width. (Step 1) First, the target reflection characteristics (operating frequency, incident angle, and reflection angle) are set. (Step 2) Next, the size Lx of the reflection control region is determined using equation (3). (Step 3) Next, the size Lx of the reflection control region is divided into n parts. The size of the unit cell is determined. (Step 4) Next, the reflection phase of the unit cell is analyzed using the element width wx and element length lx as design parameters. The reflection phase is derived using the element width wx and element length lx of the element pattern as design parameters, and analysis results are obtained that show the relationship between the element width wx, element length lx, and reflection phase in the unit cell. (Step 5) Next, the ideal reflection phase or impedance for achieving the reflection characteristics of the target reflection control region is calculated using equations (5) to (10), and the element width wx and element length lx that achieve the desired reflection phase or impedance are selected based on the analysis results. (Step 6) Next, a reflectarray is formed so as to include at least one reflection control region. The reflection characteristics of the reflectarray are analyzed. (Step 7) Note that, based on the analysis results of step 7, it is also possible to further fine-tune the element width wx and element length lx using an optimization method so as to further increase the RCS at the target reflection angle and reduce the RCS at angles other than the target angle.

[0051] (Element Pattern) The element pattern will be described in detail with reference to FIGS. 2, 9, and 10. Here, a detailed description will be given of the cross patch shape, but the element pattern shape is not limited to this. For example, it may be a circular shape, a rectangular shape, or a square shape. Generally, a reflectarray changes the reflection characteristics by utilizing resonance caused by the element pattern. Here, a linear or rectangular element pattern (square patch) mainly resonates polarized waves in the direction along its major axis, and it is known that when an element pattern with a shape that is orthogonal to these is used, it can accommodate both TE and TM polarized waves.

[0052] In the reflectarray of the present disclosure, as the division numbers n and m of the reflection control region increase, the size of each unit cell and the size of the element pattern become smaller. Because resonance occurs only when a certain element pattern size is satisfied for the frequency, if n and m are increased beyond a certain value, it becomes difficult to achieve asymmetric reflection at the operating frequency. On the other hand, as n and m are increased, the reflection characteristics can be controlled for each smaller region, and the reflection characteristics of the reflectarray approach the theoretical characteristics.

[0053] The element pattern in the reflectarray according to the present disclosure includes a cross patch in the xy plane, in which two square patches intersect at right angles. As shown in FIG. 3 , the square patch constituting the cross patch, having its long side in the x-axis direction, has an element length lx, which is the size of the long side, and an element width wy, which is the size of the short side, while the square patch having its long side in the y-axis direction has an element length ly, which is the size of the long side, and an element width wx, which is the size of the short side. Therefore, the element pattern in unit cell 4n can be expressed as having element lengths lxn and lyn and element widths wxn and wyn.

[0054] 9A and 9B are diagrams showing the configuration of an element pattern. One element pattern is arranged in a unit cell. The cross patches constituting the element pattern of a unit cell 4 may be such that the intersection point of two square patches is the same as the center of gravity of the unit cell (unit cell 4d in FIG. 9A), or may be different (unit cell 4e in FIG. 9B and unit cell 4f in FIG. 9C). These cross patch variations can be selected as appropriate, which can increase the flexibility and scalability of the design.

[0055] In the present disclosure, the element widths wx and wy are treated as design parameters, and each element pattern included in the reflection control region is designed to have a different element width. The element width wx can be varied within a range up to a value equal to the element length lx, and the element width wy can be varied within a range up to a value equal to the element length ly. The element widths wx and wy within the same element pattern may be equal or different. When different values ​​are used, the characteristics for TE and TM polarization can be controlled individually.

[0056] In the reflection control regions described so far, the element length lx in the x-axis direction is equal for each element pattern, and the element length ly in the y-axis direction is equal for each element pattern. Here, lx and ly may be equal or different. When lx and ly are different, characteristics for TE and TM polarization can be individually imparted to each element pattern.

[0057] The element pattern preferably has a surface resistance of 100 Ω / □ or less. Materials used for the element pattern include conductive materials such as inorganic oxide materials, metal materials, and conductive organic materials. Examples of inorganic oxide and metal materials include indium tin oxide (ITO), indium oxide-zinc oxide (IZO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), antimony-doped tin oxide (ATO), Ag, Al, Au, Pt, Pd, Cu, Co, Cr, In, Ag—Cu, Cu—Au, and Ni. Nanoparticles or nanowires containing at least one of these materials may also be used. Examples of conductive organic materials include polythiophene derivatives, polyacetylene derivatives, polyaniline derivatives, polypyrrole derivatives, carbon nanotubes, and graphene. Cu and Al are particularly preferred from the standpoints of material cost, conductivity, and film formability. Furthermore, a transparent reflect array can be fabricated by using ITO or a mixture of polyethylenedioxythiophene (PEDOT) and polystyrene sulfonic acid (PSS) (PEDOT / PSS). The thickness of the element pattern is, for example, 10 nm to 18 μm. From the viewpoints of flexibility, film formation, stability, sheet resistance, and low cost, it is preferable to use a film formed by vapor deposition as the element pattern.

[0058] The material of the element pattern may be the same as that of the ground layer described below, or a different material may be used. For example, at least one of the layers of the ground layer or the element pattern may be formed from Cu or Al. Cu has excellent conductivity, which reduces conductor loss. Al has low density, is lightweight, and is inexpensive, allowing for the formation of a lightweight and inexpensive reflect array. Furthermore, the thickness of at least one of the layers may be 1 μm or less. By making the thickness 1 μm or less, flexibility is improved, making it easier to install the reflect array on curved surfaces, and weight reduction is also possible.

[0059] The above materials can be used in the form of a continuous film, a mesh, or a punched shape.

[0060] Here, mesh refers to a state in which a conductor has a mesh-like opening (opening) on ​​its plane. When the conductor is formed in a mesh shape, the mesh openings may be rectangular or diamond-shaped. When the mesh openings are formed in a rectangular shape, the mesh openings are preferably square. Square mesh openings provide good design. They may also have a random shape formed by a self-organizing method. Making the mesh into a random shape can prevent moire. When processing metal into a mesh shape, methods such as punching a metal plate or etching a metal plate can be used.

[0061] When the element pattern is mesh-shaped or when a transparent conductive material is used, the reflect array exhibits visible light transparency, making it possible to maintain the appearance after installation.

[0062] When the element pattern is mesh-shaped, the line width of the mesh is preferably 5 μm or more and 30 μm or less, and more preferably 6 μm or more and 15 μm or less. The line spacing of the mesh is preferably 50 μm or more and 500 μm or less, and more preferably 100 μm or more and 300 μm or less. Furthermore, when the wavelength at the operating frequency is λ, the line spacing 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 spacing of the mesh is 0.5×λ or less, performance can be ensured. Furthermore, the line spacing of the mesh may be 0.001×λ or more.

[0063] When the element pattern is mesh-shaped or when a transparent conductive material is used, the reflect array exhibits visible light transparency, making it possible to maintain the appearance after installation.

[0064] When the element pattern is in the form of a thin film, the flexibility of the reflectarray can be improved, which makes it possible to use it on a curved surface or to carry out a roll-to-roll production process.

[0065] When the element pattern is formed using a thin film, its thickness is preferably greater than twice the skin depth calculated from Equation (11). Here, d is the skin depth, ω is the angular frequency, μ is the magnetic permeability of the material, and σ is the electrical conductivity of the material. If the thickness is less than twice the skin depth calculated from Equation (11), a portion of the electromagnetic waves incident on the conductor will be transmitted, resulting in poor reflection efficiency. Furthermore, the thickness is more preferably greater than or close to twice the skin depth calculated from Equation (11). An element pattern having a thickness sufficiently greater than twice the skin depth calculated from Equation (11) will concentrate current on the surface of the conductor due to the skin effect, with almost no current flowing in the center. Therefore, even if the thickness is greater than twice the skin depth calculated from Equation (11), the power transmission characteristics will not change significantly. The closer the value is to twice the skin depth calculated from Equation (11), the more sufficient the power transmission characteristics will be and the lower the material costs will be.

[0066] Another factor is reducing losses due to the element pattern in order to increase the reflection efficiency of electromagnetic waves. Therefore, it is preferable for the surface roughness of the element pattern to be small. At high frequencies, the skin effect causes current to concentrate on the surface of the conductor, increasing the current density on the conductor surface. This makes it susceptible to the effects of surface roughness, and the greater the surface roughness, the greater the conductor loss. In particular, when the surface roughness is greater than the skin depth, the conductor loss becomes significantly greater. Therefore, it is preferable for the surface roughness to be small in order to suppress conductor loss.

[0067] (Dielectric Layer) In addition to a simple resin, the dielectric layer may be made of a composite material in which paper, glass fiber, carbon fiber, or the like is impregnated with a resin.

[0068] The relative dielectric constant 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 dielectric constant is within the above range, it tends to be easier to obtain the desired reflection phase characteristics in the reflectarray 1. Furthermore, the dielectric loss tangent is preferably in the range of 0.00005 or more and 0.01 or less, and more preferably in the range of 0.00005 or more and 0.001 or less. When it is within the above range, a reflectarray 1 with low dielectric loss can be produced.

[0069] Examples of simple resins include polyethylene (εr=2.2 to 2.4), polypropylene (εr=2.0 to 2.6), polystyrene (εr=2.4 to 2.6), polyvinyl chloride (εr=2.8 to 8.0), AS resin (εr=2.6 to 3.1), ABS resin (εr=2.4 to 4.1), polyethylene terephthalate (εr=2.9 to 3.0), acrylic resin (εr=2.7 to 4.5), urethane resin (εr=4.0 to 7.1), epoxy resin (εr=2.5 to 6.0), nylon (εr Examples of suitable dielectric materials include polyimide (εr = 3.0 to 5.0), polyimide (εr = 2.4 to 2.7), fluororesin (εr = 2.0 to 2.6), polycarbonate (εr = 2.9 to 8.9), polyphenylene ether (εr = 2.8 to 8.2), polyphenylene sulfide (εr = 3.2 to 4.6), polyvinylidene fluoride (εr = 6.4 to 10.0), polyethylene naphthalate (εr = 2.9), phenolic resin (εr = 3.0 to 12.0), and cycloolefin polymer (εr = 2.3 to 2.5). Here, εr indicates the relative dielectric constant. Polyethylene terephthalate (PET) is particularly preferred due to its low cost and versatility. The dielectric layer can be a single layer or multiple layers. The dielectric layer may also be made of a foamed version of the above materials. A highly flexible foam is preferred.

[0070] Examples of composite materials include composite materials of paper / phenol resin, paper / epoxy resin, glass / epoxy resin, and glass / fluororesin.

[0071] From the viewpoint of adjusting the dielectric constant, a mixture containing resin components or a dielectric compound and a resin component can be used. The dielectric constant of the mixture can be adjusted by selecting the dielectric compound and its content.

[0072] The dielectric constant of a mixture can be predicted, for example, by using the Maxwell-Garnett law. In a mixture of a dielectric A having a dielectric constant εa and a dielectric B having a dielectric constant εb, when the volume fraction of A is δa, the dielectric constant εm of the mixture is expressed by the relational expression of formula (12).

[0073] Examples of the dielectric compound include barium titanate (εr=250 to 20,000), titanium oxide (εr=83 to 183), lead zirconate titanate, strontium tantalate bismuthate, and bismuth ferrite.

[0074] When a transparent dielectric is used, the reflectarray exhibits visible light transmittance, making it possible to maintain the appearance after installation.

[0075] The thickness of the dielectric layer is selected appropriately depending on 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 1. On the other hand, if it is too thick, it tends to become difficult to ensure the reflection phase, lose flexibility, and increase the total thickness of the reflectarray, making it difficult to save space. For this reason, 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, setting the thickness of the dielectric layer to a few μm or more and 100 μm or less makes it easier to design the reflectarray.

[0076] The dielectric layer can be formed by, for example, wet coating such as die coating, comma coating, or gravure coating, melt extrusion such as T-die method or inflation method, calendar film formation method, solution casting method, hot press method, etc. Alternatively, a co-extrusion method in which a plurality of resins are extruded in multiple layers to form a film may be used.

[0077] (Ground Layer) The ground layer is provided to reflect electromagnetic waves that reach the reflect array. The ground layer is made of a conductive material such as an inorganic oxide material, a metal material, or a conductive organic material.

[0078] For example, inorganic oxide materials and metal materials include indium tin oxide (ITO), indium oxide-zinc oxide (IZO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), antimony-doped tin oxide (ATO), Ag, Al, Au, Pt, Pd, Cu, Co, Cr, In, Ag—Cu, Cu—Au, and Ni. Nanoparticles or nanowires containing at least one of these materials may also be used. Examples of conductive organic materials include polythiophene derivatives, polyacetylene derivatives, polyaniline derivatives, polypyrrole derivatives, carbon nanotubes, and graphene. Cu and Al are particularly preferred from the standpoints of material cost, conductivity, and film formability. Furthermore, in order to reflect electromagnetic waves, it is desirable that the surface resistance of the ground layer be 100 Ω / □ or less. If this condition can be met, a transparent reflect array can be produced by using ITO or a mixture of polyethylene dioxythiophene (PEDOT) and polystyrene sulfonic acid (PSS) (PEDOT / PSS).

[0079] The above materials can be used in the form of a continuous film, a mesh, a punched shape, or a periodic structure.

[0080] Here, mesh refers to a state in which a conductor has a mesh-like opening (opening) on ​​its plane. When the conductor is formed in a mesh shape, the mesh openings may be rectangular or diamond-shaped. When the mesh openings are formed in a rectangular shape, the mesh openings are preferably square. Square mesh openings provide good design. They may also have a random shape formed by a self-organizing method. Making the mesh into a random shape can prevent moire. When processing metal into a mesh shape, methods such as punching a metal plate or etching a metal plate can be used.

[0081] When the ground layer is mesh-like or a transparent conductive material is used, the reflect array is transparent to visible light, allowing the appearance to be maintained after installation.

[0082] When the ground layer is mesh-shaped, the line width of the mesh is preferably 5 μm or more and 30 μm or less, and more preferably 6 μm or more and 15 μm or less. The line spacing of the mesh is preferably 50 μm or more and 500 μm or less, and more preferably 100 μm or more and 300 μm or less. Furthermore, when the wavelength at the operating frequency is λ, the line spacing 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 spacing of the mesh is 0.5×λ or less, performance can be ensured. Furthermore, the line spacing of the mesh may be 0.001×λ or more.

[0083] When a metal material is used, the ground layer can be formed by dry coating such as sputtering or vapor deposition, wet coating such as gravure coating or die coating by turning the metal material into ink, or surface treatment such as plating. Alternatively, a rolled metal plate can be used as the ground layer. When an inorganic oxide material is used, dry coating can be selected as the method for forming the ground layer 11. When an organic material is used, wet coating can be selected as the method for forming the ground layer 11. Alternatively, the ground layer can be formed by painting or spraying.

[0084] If the ground layer is in the form of a thin film formed by plating or vapor deposition, the flexibility of the reflect array can be improved, making it possible to use it on curved surfaces or to implement a roll-to-roll production process.

[0085] When the ground layer is in the form of a thin film, its thickness is preferably larger than the skin depth calculated from equation (11) in the same manner as the element pattern.

[0086] Furthermore, in order to increase the reflection efficiency of electromagnetic waves, it is also necessary to reduce loss due to the ground layer, so it is preferable that the surface roughness of the ground layer is small.

[0087] When the ground layer has a periodic structure, it can selectively reflect or transmit specific frequencies. For example, when a structure with periodically arranged patch-like conductive patterns is used as the ground layer, it is possible to reflect only specific frequencies, thereby imparting the ability to transmit frequencies other than the operating frequency. Furthermore, when a structure with periodically arranged holes where no conductive material exists is used, it is possible to design a reflect array that asymmetrically reflects the operating frequency while transmitting only specific frequencies.

[0088] (Manufacturing Method) The main manufacturing method for the basic configuration of a reflectarray is to form an element pattern by cutting or etching a copper-clad laminate used in printed circuit boards, etc., or a dielectric layer on one or both sides of which a metal film is formed by dry coating using a vapor deposition method or sputtering method, plating process, wet coating, etc. Specifically, a copper-clad laminate is formed by laminating copper foil to an insulator, for example, a substrate such as glass cloth impregnated with a resin such as epoxy. A copper-clad laminate has a plate-like shape, and copper foil is laminated to both sides of the plate-like insulator. The copper foil on one side serves as the element pattern 1, and the copper foil on the other side serves as the ground layer 3. The insulator corresponds to the dielectric layer 2. When metal films are formed on both sides of the dielectric, the element pattern 1 is formed from one metal film, and the other metal film serves as the ground layer 3. The dielectric serves as the dielectric layer 2.

[0089] FIG. 10 shows an example of the shape of the element pattern after etching. FIG. 10( a) shows a plan view of the element pattern 1, and FIGS. 10( b) to 10( d) show cross-sectional views of the element pattern 1. As shown in FIG. 10( a), the element pattern 1 is formed by orthogonally intersecting a square patch having an element length lx and an element width wy with a square patch having an element length ly and an element width wx. Either dry etching or wet etching may be used for the etching method. When etching is used, corner rounding ( FIG. 10( a)) or pinholes may occur in the element pattern 1. It is also expected that a forward taper ( FIG. 10( b)), a reverse taper ( FIG. 10( c)), or rounding ( FIG. 10( d)) may be formed in the cross-section of the element pattern 1. In FIG. 10, the thickness of the element pattern 1 is denoted by t. When etching is used, the cross-sectional shape of the element pattern is preferably a forward taper shape that widens in the −z-axis direction. The forward tapered shape increases the surface area of ​​the element pattern, making it possible to increase the adhesive strength with the functional layer when the functional layer is laminated, as will be described later.

[0090] Generally, in the case of cutting, the dimensional error of the element pattern is about ±100 μm, and in the case of etching, the dimensional error of the element pattern is about ±50 μm.

[0091] Other manufacturing methods include directly forming the element pattern and ground layer on the dielectric layer, printing using letterpress printing, lithographic printing, intaglio printing, stencil printing, transfer printing, etc., or masking the dielectric layer except for the element pattern area with masking tape or a masking agent, and then forming the element pattern using dry coating, plating, painting, or spraying.

[0092] Lamination of other layers (functional layers such as protective layers, adhesive layers, design layers, installation layers, etc.) onto the basic structure can be achieved by laminating, printing / coating, or extrusion molding. Examples of laminating methods include, but are not limited to, dry laminating, wet laminating, thermal laminating, and extrusion laminating.

[0093] [Embodiment A] Embodiment A will be described. In this embodiment, the "incident angle" refers to the incident angle θi of an electromagnetic wave incident on the reflection control area, and the "reflection angle" refers to the reflection angle θr of an electromagnetic wave reflected from the reflection control area. When the wavelength of the electromagnetic wave reflected from the reflection control area is λ, the reflection control area is designed to satisfy the following formula (1): When specifically indicating the incident angle and reflection angle as designed, they are expressed as "incident angle or reflection angle that satisfies formula (1)," which indicates the relationship between the designed incident angle, reflection angle, and reflection control area. The "incident deviation angle" refers to the angle of deviation when the incident angle deviates from the reference angle (=0°) that satisfies formula (1). The angle expression for the "incident deviation angle" is expressed as a positive angle (0° to 180°) toward the +z-axis direction and a negative angle (0° to -180°) toward the -z-axis direction, with the reference angle (=0°) being the incident angle that satisfies formula (1). Furthermore, the "acceptable incident angle range" Δθi refers to the angle range of incident deviation angles within which the reflection intensity of the electromagnetic wave, which the reflection control area reflects from the incident deviation angle to the reflection angle, is within -3 dB, with the reference (=0 dB) being the reflection intensity of the electromagnetic wave, which the reflection control area reflects from the incident deviation angle to the reflection angle. -3 dB indicates that the power is half of the reference value. The -3 dB reference is used in the antenna industry as a standard for indicating directivity, and within that range, communication is considered sufficient. In this embodiment, the "acceptable incident angle range" is defined as the performance of a reflectarray in which eight reflection control areas are prepared and arranged so that the length of one side is 8L. However, the reflectarray in the scope of this claim is not limited to "a reflectarray in which eight reflection control areas are prepared and arranged so that the length of one side is 8L."

[0094] In this embodiment, the "electromagnetic wave reflection system" is composed of three components: a transmitter, a reflectarray, and a receiver. The "transmitter" refers to a device that emits electromagnetic waves or a device that reflects electromagnetic waves from a device that emits electromagnetic waves. Specific examples include a wireless base station, a mobile station, a repeater, a mobile body, a communication terminal, and a reflector. The "receiver" refers to a device that receives electromagnetic waves, and specific examples include a wireless base station, a mobile station, a repeater, a mobile body, a communication terminal, and a reflector. In this embodiment, the "primary radiation" refers to the electromagnetic waves emitted from the transmitter in the electromagnetic wave reflection system. The "secondary radiation" refers to the electromagnetic waves emitted from the reflectarray in the electromagnetic wave reflection system, and is the radiation of electromagnetic waves generated when the electromagnetic waves primarily emitted from the transmitter are incident on the reflectarray.

[0095] (Relationship between Incident Angle and Reflection Angle) In this embodiment, the incident angle of the reflectarray is preferably −70° or more and −45° or less, or +45° or more and +70° or less. The larger |θi| is, the wider the incident angle range of the reflectarray becomes, and electromagnetic waves incident from this angle range can be reflected in the reflection angle direction.

[0096] The reflection angle in the reflectarray must satisfy equation (2). Within this range, the reflectarray can reflect electromagnetic waves incident from a wide range of angles in the reflection angle direction. More preferably, the reflection angle θr is between -30° and +30°, and even more preferably between -20° and +20°. The closer the reflection angle is to 0°, the wider the range of angles that the reflectarray can reflect electromagnetic waves incident from, in the reflection angle direction, ensuring a wide range of allowable incident angles.

[0097] (Acceptable Incident Angle Range) The reflectarray can have a wider acceptable incident angle range as the absolute value of the incident angle |θi| increases. Furthermore, within a range where the absolute value of the incident angle |θi| is large, the more the incident deviation angle is positive, the wider the acceptable incident angle range, ensuring a wider acceptable incident angle range. This is thought to be because the apparent area of ​​the reflectarray viewed from the transmitter is smaller, resulting in less energy impinging on the reflectarray and therefore less reflected power. The acceptable incident angle range Δθi is preferably greater than 5.5° and less than 16°. An acceptable incident angle range smaller than 5.5° requires accurate determination of the direction of the electromagnetic waves radiated from the transmitter. Furthermore, even when a beamforming antenna is used for the transmitter, more antenna elements must be arranged to increase the angular accuracy of the beamforming, which leads to a larger transmitter area and higher costs. Furthermore, an acceptable incident angle range of 16° or more may reflect radio wave sources other than the transmitter, which may cause phase disturbance.

[0098] (Electromagnetic Wave Reflection System) An example of an electromagnetic wave reflection system and an installation method of a reflectarray will be described with reference to FIG. 11 . FIG. 11 is a diagram showing an example of an electromagnetic wave reflection system using a reflectarray. For ease of explanation, FIG. 11 is used as an example, but the environment in which the electromagnetic wave reflection system is used is not limited to this. As shown in the example of FIG. 11 , if there is a shielding object 500, the electromagnetic waves radiated from the transmitter are blocked by the shielding object and cannot reach the receiver directly. The higher the frequency, the more linear the electromagnetic waves are, making it more difficult for them to reach the back of the shielding object. Here, by using a reflectarray, the electromagnetic waves radiated primarily from the transmitter hit the reflectarray, and the electromagnetic waves radiated secondarily from the reflectarray hit the receiver, thereby enabling the electromagnetic waves to be delivered from the transmitter to the receiver. Generally, when constructing an electromagnetic wave reflection system using a passive reflector, the usage environment is confirmed in advance, the installation location of the passive reflector, the angle of incidence, and the angle of reflection are calculated, and the passive reflector is designed based on this. In this case, if the confirmation is not accurate in advance, the maximum effect cannot be achieved. In addition, accurate angle adjustment is required when installing the passive reflector. Here, by using the reflectarray of this embodiment, even if an incident angle deviation occurs, the electromagnetic wave incident on the reflectarray can be reflected in the reflection angle direction within the range of the incident angle and reflection angle that satisfies Equation (2), and the allowable incident angle range can be widened, making it easier to construct an electromagnetic wave reflection system.

[0099] (Installation Method of Reflectarray) In order to minimize installation space, it is preferable that the reflectarray be installed along a wall or the like. Specifically, in FIG. 11, installation on walls 200 and 201 is assumed. The reflectarray installed on wall 200 is shown as 20 １ The reflectarray installed on the wall 201 is designated as 202. １is an installation method that satisfies the formula (2), while the reflectarray 202 is an installation method that does not satisfy the formula (2). The installation method of the reflectarray 202 requires high precision in determining the positional relationship between the transmitter and the reflectarray 202, and if there is a deviation in the installation position, the power that the receiver can receive will change significantly. １ By installing a reflectarray, the allowable incident angle range is widened, and electromagnetic waves incident within this angle range can be reflected toward the receiver with a stable reflection intensity. From a practical perspective, for example, the accuracy of the reflectarray installation position during construction is relaxed, making construction easier. Furthermore, when an antenna with beamforming is used for the transmitter, the beamforming accuracy can also be relaxed.

[0100] (Support) The reflectarray is mounted on a support. FIG. 12 is a diagram showing an example of a reflectarray mounted on a support. The support may be an existing sign, wall, ceiling, window glass, etc., or a newly installed panel or pole. To minimize installation space, it is preferable to attach it to an existing sign, wall, ceiling, window glass, etc., as shown in FIG. 12( a). Furthermore, a design layer may be provided to harmonize with the space, or transparency may be imparted by meshing the elements or ground layer. Furthermore, when a new panel or pole is installed, as shown in FIG. 12( b), it is preferable to have a mechanism (support position adjustment jig 601) that can adjust the angle of the reflectarray in the vertical or horizontal directions, and more preferably, to have a mechanism that can move the position of the reflectarray up, down, left, and right. The reflectarray is mounted on a support 600 and used as a reflectarray device.

[0101] (Installation Layer) The installation layer is a layer for fixing the reflectarray to the support. For example, an adhesive layer, a pressure-sensitive adhesive layer, or a magnet can be used when the support is made of metal.

[0102] (Design Layer) The design layer is a layer for imparting design to the surface of the reflectarray. For example, when used as a building material such as wallpaper, a design layer may be further provided to harmonize with the space. Furthermore, when used as a whiteboard, a functional film may be used as the design layer. The design layer may be given the function of the protective layer described below.

[0103] (Protective Layer) For the protective layer, a film or sheet having gas barrier properties, water vapor barrier properties, water resistance, abrasion resistance, and scratch resistance may be used to prevent oxidation deterioration, physical damage, and peeling of the element pattern and ground layer.

[0104] When it is assumed that the reflectarray will be used indoors, it is preferable to use a protective layer that has antibacterial properties, antiviral properties, contamination resistance, etc. When it is assumed that the reflectarray will be used outdoors, weather resistance is required, and therefore a layer containing UVA (ultraviolet absorber) or HALS (light stabilizer) may be used.

[0105] [Evaluation Results (Examples and Comparative Examples)] Table A1 summarizes the results for Examples A1-A4 and Comparative Examples A1-A4, and Table A2 summarizes the results for Examples A5-A10 and Comparative Examples A5-A10. The comparative examples used here compare cases where the same reflectarray satisfies and does not satisfy Equation (2) in order to demonstrate that the reflectarray of this embodiment has a wide acceptable incident angle range at a specific incident angle. The ease of installation in Tables A1 and A2 is an index showing the extent to which installation error of the reflectarray is tolerable. When the distance between the transmitter and the reflectarray is 5 m, if the reduction in received power is within -3 dB even when the reflectarray is moved 45 cm, it is marked as ◯, and if the reduction in received power is greater than -3 dB, it is marked as ×. When the reflector is one that provides asymmetric reflection in the x-axis direction, the direction in which the reflectarray is moved is parallel to the x-axis. Reception stability is an index showing the stability of received power at a reflection angle that satisfies Equation (1) when the transmitter is moved. The transmitter is moved so as to change the incident deviation angle, and if the angle width (i.e., the incident allowable angle range) at which the received power at the reflection angle becomes -3 dB is 5.5° or less, the received power is judged as unstable and marked with an X, and if it is greater than 5.5° and less than 16°, the received power is stable and marked with an O.

[0106] (Example A1) A reflect array 20 having a basic configuration was constructed using copper with a thickness of 0.018 mm for the element pattern 1 and the ground layer 3, and a glass / fluororesin composite material with a thickness of 0.764 mm for the dielectric layer 2. However, the conductivity of copper was set to 5.8×10 siemens / m, the real part of the relative dielectric constant of the dielectric layer 2 was set to 2.6, and tan δ was set to 0.0025.

[0107] The operating frequency was set to 28 GHz, the target reflection characteristics (desired reflection characteristics) were set to θix = −45°, θrx = 0°, and θiy = θry = 0°, and the size Lx of reflection control area 5 in the x-axis direction was determined to be 15.142 mm using equation (3).

[0108] The number of divisions of reflection control region 5 was set to 3, and the size of the unit cell in the x-axis direction and the y-axis direction was set to 3.785 mm. The shape of the element pattern was a cross patch in which two square patches intersected at right angles in the xy plane. Here, the element lengths and element widths were different in each element pattern in reflection control region 5, and the element lengths and element widths in the x-axis direction and the y-axis direction were set to be the same within the same element pattern. Specifically, the element lengths were set to lx1 = ly1, lx2 = ly2, and lx3 = ly3, and the element widths were set to wx1 = wy1, wx2 = wy2, and wx3 = wy3. In Tables A1 and A2 and in the figures and text in the following description, the unit cells included in reflection control region 5 are represented as unit cell 1, unit cell 2, ..., unit cell p (p is an integer greater than or equal to 1 and less than or equal to the number of divisions n), and in unit cell p, the element length in the x-axis direction is represented as lxp, the element length in the y-axis direction as lyp, the element width in the x-axis direction as wxp, and the element width in the y-axis direction as wyp. However, the subscripts x and y are omitted when lxp and lyp are equal, and the subscripts x and y are omitted when wxp and wyp are equal, and the subscript p may be omitted when the unit cell is not specified.

[0109] The reflection phase of the unit cell for each element width w and element length l was analyzed using finite element analysis software (HFSS) manufactured by Ansys. It was confirmed that the reflection phase changed as the element width w or element length l changed when the element width w or element length l was 1.400 mm.

[0110] Next, based on the analysis results of the reflection phase of the unit cell obtained above, the element length l of each unit cell was determined so as to follow the impedance distribution of equation (9). The element lengths l were set to lx1 = ly1 = 3.800 mm, lx2 = ly2 = 3.000 mm, and lx3 = ly3 = 1.400 mm, and the element widths were set to wx1 = wy1 = 1.400 mm, wx2 = wy2 = 1.400 mm, and wx3 = wy3 = 1.100 mm, respectively.

[0111] The reflectarray 20 had 8 x 6 reflection control areas arranged in the x-axis and y-axis directions, and its size in the xy plane was 121.12 mm x 90.840 mm. HFSS was used to analyze the reflection characteristics when polarized waves parallel to the y-axis were irradiated onto the reflectarray 20 at θix = -45° and θrx = 0°.

[0112] In order to grasp the allowable incident angle range, a similar analysis was performed when the angle was changed in 2° increments within the range of −65°≦θix≦−25°.

[0113] Fig. 13 shows the analysis results of the reflectarray 20 obtained in Example A1. In Fig. 13, the horizontal axis represents the reflection angle θrx, and the vertical axis represents RCS (radar cross section). RCS is a value that substantially corresponds to the intensity of the reflected wave. In the reflectarray 20 of Example A1, the electromagnetic wave incident at θix = -45° was reflected in the desired direction of θrx = 0°, and the RCS was -0.02 dBsm.

[0114] (Comparative Example A1) A reflectarray similar to the reflectarray described in Example A1 was prepared except for the incident angle θix and the reflection angle θrx. The incident angle θix and the reflection angle θrx were set to θix = 0° and θrx = -45°, respectively. The reflection characteristics of the reflectarray 20 were analyzed using HFSS.

[0115] In order to grasp the allowable incident angle range, a similar analysis was performed when the angle was changed in 2° increments within the range of −20°≦θix≦20°.

[0116] 14 shows the analysis results of the reflectarray 20 obtained in the comparative example A1. In the reflectarray 20 of the example A1, the electromagnetic wave incident at θix=0° was reflected in the desired direction of θrx=−45°, and the RCS was −0.28 dBsm.

[0117] FIG. 15 shows a comparison of the amount of change in power that can be received at a specific reflection angle θrx when the incident angle is changed for Example A1 and Comparative Example A1. The horizontal axis of FIG. 15 represents the incident deviation angle, and the vertical axis represents the amount of change in RCS when the RCS when the incident deviation angle = 0° is set to 0 dB. Specifically, in Example A1, when the incident deviation angle = 0°, θix = -45°, and the angle when the incident deviation angle is changed by -65° ≦ θix ≦ -25° is shown on the horizontal axis of FIG. 15 as -20° ≦ incident deviation angle ≦ 20°. The vertical axis shows how much the RCS has changed compared to when the incident deviation angle = 0°, assuming that the RCS (-0.02 dBsm) at θrx = 0° is 0 dB. This is equivalent to showing how much the received power at the reflection angle has changed. In addition, in Comparative Example A1, when the incident deviation angle is 0°, θix = 0°, and the angle when changed by -20°≦θix≦20° is shown on the horizontal axis of Fig. 15 as -20°≦incident deviation angle≦20°. The vertical axis shows how much the RCS has changed compared to when the incident deviation angle is 0°, with the RCS (-0.28 dBsm) at θrx = -45° being set to 0 dB. The dotted line at -3 dB indicates the regulation of the allowable incident angle range.

[0118] 15, the acceptable incident angle range was 6.2° for Example A1 and 4.2° for Comparative Example A1. As a result of confirming ease of installation, in Example A1, even when the reflectarray was moved 45 cm, the change in received power was within -3 dB in the direction of the receiving angle that satisfied formula (1), whereas in Comparative Example A1, the change was greater than -3 dB. Furthermore, as a result of confirming reception stability, in Example A1, the received power was stable in a range where the acceptable incident angle range was greater than 5.5°, whereas in Comparative Example A1, the received power was unstable in a range where the acceptable incident angle range was 5.5° or less.

[0119] (Example A2) A reflectarray 20 having a basic configuration was constructed using copper with a thickness of 0.018 mm for the element pattern 1 and the ground layer 3, and a glass / fluororesin composite material with a thickness of 0.764 mm for the dielectric layer 2. However, the conductivity of copper was set to 5.8×10 siemens / m, the real part of the relative dielectric constant of the dielectric layer 2 was set to 2.6, and tan δ was set to 0.0025.

[0120] The operating frequency was set to 28 GHz, the target reflection characteristics (desired reflection characteristics) were set to θix = -50°, θrx = 0°, and θiy = θry = 0°, and the size Lx of reflection control area 5 in the x-axis direction was determined to be 13.977 mm using equation (3).

[0121] The number of divisions of reflection control region 5 was set to 3, and the size of the unit cell in the x-axis direction and the y-axis direction was set to 4.659 mm. The shape of the element pattern was a cross patch in which two square patches intersected at right angles in the xy plane. Here, the element lengths and element widths were different in each element pattern in reflection control region 5, and the element lengths and element widths in the x-axis direction and the y-axis direction were set to be the same within the same element pattern. Specifically, the element lengths were set to lx1 = ly1, lx2 = ly2, and lx3 = ly3, and the element widths were set to wx1 = wy1, wx2 = wy2, and wx3 = wy3.

[0122] The reflection phase of the unit cell for each element width w and element length l was analyzed using finite element analysis software (HFSS) manufactured by Ansys. It was confirmed that the reflection phase changed as the element width w or element length l changed.

[0123] Next, based on the analysis results of the reflection phase of the unit cell obtained above, the element length l of each unit cell was determined so as to conform to the impedance distribution of equation (9). The element lengths l were set to lx1 = ly1 = 3.790 mm, lx2 = ly2 = 2.775 mm, and lx3 = ly3 = 2.065 mm, and the element widths were set to wx1 = wy1 = 2.303 mm, wx2 = wy2 = 2.217 mm, and wx3 = wy3 = 2.024 mm, respectively.

[0124] The reflectarray 20 had 8 x 6 reflection control areas arranged in the x-axis and y-axis directions, and its size in the xy plane was 111.816 mm x 27.954 mm. The reflection characteristics when polarized waves parallel to the y-axis were irradiated onto the reflectarray 20 at θix = -50° and θrx = 0° were analyzed using HFSS.

[0125] In order to grasp the allowable incident angle range, a similar analysis was performed when the angle was changed in 2° increments within the range of −70°≦θix≦−30°.

[0126] Fig. 16 shows the analysis results of the reflectarray 20 obtained in Example A2. In Fig. 16, the horizontal axis represents the reflection angle θrx, and the vertical axis represents the RCS. In the reflectarray 20 of Example A2, the electromagnetic wave incident at θrx = -50° was reflected in the desired direction of θrx = 0°, and the RCS was -1.82 dBsm.

[0127] (Comparative Example A2) A reflectarray similar to the reflectarray described in Example A2 was prepared except for the incident angle θix and the reflection angle θrx. The incident angle θix and the reflection angle θrx were set to θix = 0° and θrx = -50°, respectively. The reflection characteristics of the reflectarray 20 were analyzed using HFSS.

[0128] In order to grasp the allowable incident angle range, a similar analysis was performed when the angle was changed in 2° increments within the range of −20°≦θix≦20°.

[0129] 17 shows the analysis results of the reflectarray 20 obtained in comparative example A2. In the reflectarray 20 of example A2, the electromagnetic wave incident at θix=0° was reflected in the desired direction of θrx=−50°, and the RCS was −1.89 dBsm.

[0130] FIG. 18 shows the results of comparing the amount of change in power that can be received at a specific reflection angle θrx when the incident angle is changed in Example A2 and Comparative Example A2.

[0131] 18, the acceptable incident angle range was 7.4° for Example A2 and 4.5° for Comparative Example A2. As a result of confirming ease of installation, in Example A2, even when the reflectarray was moved 45 cm, the change in received power was within -3 dB in the direction of the receiving angle that satisfied formula (1), whereas in Comparative Example A2, the change was greater than -3 dB. Furthermore, as a result of confirming reception stability, in Example A2, the received power was stable in a range where the acceptable incident angle range was greater than 5.5°, whereas in Comparative Example A2, the received power was unstable in a range where the acceptable incident angle range was 5.5° or less.

[0132] (Example A3) A reflectarray 20 having a basic configuration was constructed using copper with a thickness of 0.018 mm for the element pattern 1 and the ground layer 3, and a glass / fluororesin composite material with a thickness of 0.764 mm for the dielectric layer 2. However, the conductivity of copper was set to 5.8×10 siemens / m, the real part of the relative dielectric constant of the dielectric layer 2 was set to 2.6, and tan δ was set to 0.0025.

[0133] The operating frequency was set to 28 GHz, the target reflection characteristics (desired reflection characteristics) were set to θix = -60°, θrx = 0°, and θiy = θry = 0°, and the size Lx of reflection control area 5 in the x-axis direction was determined to be 12.363 mm using equation (3).

[0134] The number of divisions of reflection control region 5 was set to 3, and the size of the unit cell in the x-axis direction and the y-axis direction was set to 4.121 mm. The shape of the element pattern was a cross patch in which two square patches were orthogonal to each other in the xy plane. Here, the element lengths and element widths were different in each element pattern in reflection control region 5, and the element lengths and element widths in the x-axis direction and the y-axis direction were set to be the same within the same element pattern. Specifically, the element lengths were set to lx1 = ly1, lx2 = ly2, and lx3 = ly3, and the element widths were set to wx1 = wy1, wx2 = wy2, and wx3 = wy3.

[0135] The reflection phase of the unit cell for each element width w and element length l was analyzed using finite element analysis software (HFSS) manufactured by Ansys. It was confirmed that the reflection phase changed as the element width w or element length l changed.

[0136] Next, based on the analysis results of the reflection phase of the unit cell obtained above, the element length l of each unit cell was determined so as to conform to the impedance distribution of equation (9). The element lengths l were set to lx1 = ly1 = 2.051 mm, lx2 = ly2 = 3.614 mm, and lx3 = ly3 = 2.815 mm, and the element widths were set to wx1 = wy1 = 1.427 mm, wx2 = wy2 = 1.521 mm, and wx3 = wy3 = 1.699 mm, respectively.

[0137] The reflectarray 20 had 8 x 6 reflection control areas arranged in the x-axis and y-axis directions, and its size in the xy plane was 98.904 mm x 24.726 mm. The reflection characteristics when polarized waves parallel to the y-axis were irradiated onto the reflectarray 20 at θix = -60° and θrx = 0° were analyzed using HFSS.

[0138] In order to grasp the allowable incident angle range, a similar analysis was performed when the angle was changed in 2° increments within the range of −80°≦θix≦−40°.

[0139] Fig. 19 shows the analysis results of the reflectarray 20 obtained in Example A3. In Fig. 19, the horizontal axis represents the reflection angle θrx, and the vertical axis represents the RCS. In the reflectarray 20 of Example A3, the electromagnetic wave incident at θix = -60° was reflected in the desired direction of θrx = 0°, and the RCS was -6.14 dBsm.

[0140] (Comparative Example A3) A reflectarray similar to the reflectarray described in Example A3 was prepared except for the incident angle θix and the reflection angle θrx. The incident angle θix and the reflection angle θrx were set to θix = 0° and θrx = -60°, respectively. The reflection characteristics of the reflectarray 20 were analyzed using HFSS.

[0141] In order to grasp the allowable incident angle range, a similar analysis was also performed when the angle was changed in 2° increments within the range of −20°≦θix≦20°.

[0142] 20 shows the analysis results of the reflectarray 20 obtained in comparative example A3. In the reflectarray 20 of example A3, the electromagnetic wave incident at θix=0° was reflected in the desired direction of θrx=−60°, and the RCS was −6.22 dBsm.

[0143] FIG. 21 shows the comparison results of the amount of change in power that can be received at a specific reflection angle θrx when the incident angle is changed in each of Example A3 and Comparative Example A3.

[0144] From the results of Figure 21, the acceptable incident angle range was 10.8° for Example A3 and 0.1° for Comparative Example A3. As a result of confirming ease of installation, in Example A3, even when the reflectarray was moved 45 cm, the change in received power was within -3 dB in the direction of the receiving angle that satisfied formula (1), whereas in Comparative Example A3, the change was greater than -3 dB. Furthermore, as a result of confirming reception stability, in Example A3, the received power was stable in a range where the acceptable incident angle range was greater than 5.5°, whereas in Comparative Example A3, the received power was unstable in a range where the acceptable incident angle range was 5.5° or less.

[0145] (Example A4) A reflectarray 20 having a basic configuration was constructed using copper with a thickness of 0.018 mm for the element pattern 1 and the ground layer 3, and a glass / fluororesin composite material with a thickness of 0.764 mm for the dielectric layer 2. However, the conductivity of copper was set to 5.8×10 siemens / m, the real part of the relative dielectric constant of the dielectric layer 2 was set to 2.6, and tan δ was set to 0.0025.

[0146] The operating frequency was set to 28 GHz, the target reflection characteristics (desired reflection characteristics) were set to θix = -70°, θrx = 0°, and θiy = θry = 0°, and the size Lx of reflection control area 5 in the x-axis direction was determined to be 11.394 mm using equation (3).

[0147] The number of divisions of reflection control region 5 was set to 3, and the size of the unit cell in the x-axis direction and the y-axis direction was set to 3.798 mm. The shape of the element pattern was a cross patch in which two square patches intersected at right angles in the xy plane. Here, the element lengths and element widths were different in each element pattern in reflection control region 5, and the element lengths and element widths in the x-axis direction and the y-axis direction were set to be the same within the same element pattern. Specifically, the element lengths were set to lx1 = ly1, lx2 = ly2, and lx3 = ly3, and the element widths were set to wx1 = wy1, wx2 = wy2, and wx3 = wy3.

[0148] The reflection phase of the unit cell for each element width w and element length l was analyzed using finite element analysis software (HFSS) manufactured by Ansys. It was confirmed that the reflection phase changed as the element width w or element length l changed.

[0149] Next, based on the analysis results of the reflection phase of the unit cell obtained above, the element length l of each unit cell was determined so as to follow the impedance distribution of equation (9). The element lengths l were set to lx1 = ly1 = 2.353 mm, lx2 = ly2 = 3.308 mm, and lx3 = ly3 = 2.786 mm, and the element widths were set to wx1 = wy1 = 1.500 mm, wx2 = wy2 = 1.500 mm, and wx3 = wy3 = 1.500 mm, respectively.

[0150] The reflectarray 20 had 8 x 6 reflection control areas arranged in the x-axis and y-axis directions, and its size in the xy plane was 91.152 mm x 22.788 mm. The reflection characteristics when polarized waves parallel to the y-axis were irradiated onto the reflectarray 20 at θix = -70° and θrx = 0° were analyzed using HFSS.

[0151] In order to grasp the allowable incident angle range, a similar analysis was performed when the angle was changed in 2° increments within the range of −90°≦θix≦−50°.

[0152] Fig. 22 shows the analysis results of the reflectarray 20 obtained in Example A4. In Fig. 22, the horizontal axis represents the reflection angle θrx, and the vertical axis represents the RCS. In the reflectarray 20 of Example A4, the electromagnetic wave incident at θix = -70° was reflected in the desired direction of θrx = 0°, and the RCS was -15.56 dBsm.

[0153] (Comparative Example A4) A reflectarray similar to the reflectarray described in Example A4 was prepared except for the incident angle θix and the reflection angle θrx. The incident angle θix and the reflection angle θrx were set to θix = 0° and θrx = -70°, respectively. The reflection characteristics of the reflectarray 20 were analyzed using HFSS.

[0154] In order to grasp the allowable incident angle range, a similar analysis was also performed when the angle was changed in 2° increments within the range of −20°≦θix≦20°.

[0155] 23 shows the analysis results of the reflectarray 20 obtained in comparative example A4. In the reflectarray 20 of example A4, the electromagnetic wave incident at θix=0° was reflected in the desired direction of θrx=−70°, and the RCS was −15.56 dBsm.

[0156] FIG. 24 shows the results of comparing the amount of change in power that can be received at a specific reflection angle θrx when the incident angle is changed in each of Example A4 and Comparative Example A4.

[0157] 24, the acceptable incident angle range was 15.3° for Example A4 and 5.5° for Comparative Example A4. As a result of confirming ease of installation, in Example A4, even when the reflectarray was moved 45 cm, the change in received power was within -3 dB in the direction of the receiving angle that satisfied formula (1), whereas in Comparative Example A4, the change was greater than -3 dB. Furthermore, as a result of confirming reception stability, in Example A4, the received power was stable in a range where the acceptable incident angle range was greater than 5.5°, whereas in Comparative Example A4, the received power was unstable in a range where the acceptable incident angle range was 5.5° or less.

[0158] From the results of Examples A1-A4 and Comparative Examples A1-A4, it was found that a large allowable incident angle range was achieved in the range that satisfied formula (2). Figure 25 shows a relationship diagram between the absolute value of the incident angle that satisfies formula (1) and the allowable incident angle range for the Examples, and a relationship diagram between the absolute value of the reflection angle that satisfies formula (1) and the allowable incident angle range for the Comparative Examples. From the results of Figure 25, it was found that in this example, the allowable incident angle range increased as |θi| increased.

[0159] The frequency dependence was confirmed using Examples A5 to A7 and Comparative Examples A5 to A7. (Example A5) A reflectarray 20 with a basic configuration was constructed using copper with a thickness of 0.018 mm for the element pattern 1 and the ground layer 3, and a glass / epoxy resin composite material with a thickness of 1.564 mm for the dielectric layer 2. However, the conductivity of copper was set to 5.8 x 10^7 siemens / m, the real part of the relative dielectric constant of the dielectric layer 2 was set to 4.5, and tan δ was set to 0.014.

[0160] The operating frequency was set to 4.85 GHz, the target reflection characteristics (desired reflection characteristics) were set to θix = −70°, θrx = 0°, and θiy = θry = 0°, and the size Lx of reflection control area 5 in the x-axis direction was determined to be 65.780 mm using equation (3).

[0161] The number of divisions of reflection control region 5 was set to 4, and the size of the unit cell in the x-axis direction and the y-axis direction was set to 16.445 mm. The shape of the element pattern was a cross patch in which two square patches intersected at right angles in the xy plane. Here, the element lengths and element widths were different in each element pattern in reflection control region 5, and the element lengths and element widths in the x-axis direction and the y-axis direction were the same within the same element pattern. Specifically, the element lengths were set to lx1 = ly1, lx2 = ly2, lx3 = ly3, and lx4 = ly4, and the element widths were set to wx1 = wy1, wx2 = wy2, wx3 = wy3, and wx4 = wy4.

[0162] The reflection phase of the unit cell for each element width w and element length l was analyzed using finite element analysis software (HFSS) manufactured by Ansys. It was confirmed that the reflection phase changed as the element width w or element length l changed.

[0163] Next, based on the analysis results of the reflection phase of the unit cell obtained above, the element length l of each unit cell was determined so as to follow the impedance distribution of equation (9). The element lengths l were lx1 = ly1 = 14.000 mm, lx2 = ly2 = 14.000 mm, lx3 = ly3 = 14.000 mm, and lx4 = ly4 = 14.000 mm, and the element widths were wx1 = wy1 = 8.303 mm, wx2 = wy2 = 5.887 mm, wx3 = wy3 = 11.538 mm, and wx4 = wy4 = 9.400 mm, respectively.

[0164] The reflectarray 20 had 8 x 6 reflection control areas arranged in the x-axis and y-axis directions, and its size in the xy plane was 206.240 mm x 38.670 mm. The reflection characteristics when polarized waves parallel to the y-axis were irradiated onto the reflectarray 20 at θix = -70° and θrx = 0° were analyzed using HFSS.

[0165] In order to grasp the allowable incident angle range, a similar analysis was performed when the angle was changed in 2° increments within the range of −90°≦θix≦−50°.

[0166] Fig. 26 shows the analysis results of the reflectarray 20 obtained in Example A5. In Fig. 26, the horizontal axis represents the reflection angle θrx, and the vertical axis represents the RCS. In the reflectarray 20 of Example A5, the electromagnetic wave incident at θix = -70° was reflected in the desired direction of θrx = 0°, and the RCS was 2.13 dBsm.

[0167] (Comparative Example A5) A reflectarray similar to the reflectarray described in Example A5 was prepared except for the incident angle θix and the reflection angle θrx. The incident angle θix and the reflection angle θrx were set to θix = 0° and θrx = -70°, respectively. The reflection characteristics of the reflectarray 20 were analyzed using HFSS.

[0168] In order to grasp the allowable incident angle range, a similar analysis was also performed when the angle was changed in 2° increments within the range of −20°≦θix≦20°.

[0169] 27 shows the analysis results of the reflectarray 20 obtained in comparative example A5. In the reflectarray 20 of example A5, the electromagnetic wave incident at θix=0° was reflected in the desired direction of θrx=−70°, and the RCS was 2.07 dBsm.

[0170] FIG. 28 shows the results of comparing the amount of change in power that can be received at a specific reflection angle θrx when the incident angle is changed in Example A5 and Comparative Example A5.

[0171] 28, the acceptable incident angle range was 15.4° for Example A5 and 5.5° for Comparative Example A5. As a result of confirming ease of installation, in Example A5, even when the reflectarray was moved 45 cm, the change in received power was within -3 dB in the direction of the receiving angle that satisfied formula (1), whereas in Comparative Example A5, the change was greater than -3 dB. Furthermore, as a result of confirming reception stability, in Example A5, the received power was stable in a range where the acceptable incident angle range was greater than 5.5°, whereas in Comparative Example A5, the received power was unstable in a range where the acceptable incident angle range was 5.5° or less.

[0172] (Example A6) A reflect array 20 having a basic configuration was constructed using copper with a thickness of 0.018 mm for the element pattern 1 and the ground layer 3, and a fluororesin material with a thickness of 0.200 mm for the dielectric layer 2. However, the conductivity of copper was set to 5.8×10 siemens / m, the real part of the relative dielectric constant of the dielectric layer 2 was set to 2.06, and tan δ was set to 0.0007.

[0173] The operating frequency was set to 60 GHz, the target reflection characteristics (desired reflection characteristics) were set to θix = −45°, θrx = 0°, and θiy = θry = 0°, and the size Lx of reflection control area 5 in the x-axis direction was determined to be 7.065 mm using equation (3).

[0174] The number of divisions of reflection control region 5 was set to 3, and the size of the unit cell in the x-axis direction and the y-axis direction was set to 2.355 mm. The shape of the element pattern was a cross patch in which two square patches intersected at right angles in the xy plane. Here, the element lengths and element widths were different in each element pattern in reflection control region 5, and the element lengths and element widths in the x-axis direction and the y-axis direction were set to be the same within the same element pattern. Specifically, the element lengths were set to lx1 = ly1, lx2 = ly2, and lx3 = ly3, and the element widths were set to wx1 = wy1, wx2 = wy2, and wx3 = wy3.

[0175] The reflection phase of the unit cell for each element width w and element length l was analyzed using finite element analysis software (HFSS) manufactured by Ansys. It was confirmed that the reflection phase changed as the element width w or element length l changed.

[0176] Next, based on the analysis results of the reflection phase of the unit cell obtained above, the element length l of each unit cell was determined so as to follow the impedance distribution of equation (9). The element lengths l were lx1 = ly1 = 1.700 mm, lx2 = ly2 = 1.700 mm, lx3 = ly3 = 1.700 mm, and lx4 = ly4 = 14.000 mm, and the element widths were wx1 = wy1 = 1.362 mm, wx2 = wy2 = 1.741 mm, and wx3 = wy3 = 1.538 mm, respectively.

[0177] The reflectarray 20 had 8 x 6 reflection control areas arranged in the x-axis and y-axis directions, and its size in the xy plane was 62.184 mm x 15.546 mm. The reflection characteristics when polarized waves parallel to the y-axis were irradiated onto the reflectarray 20 at θix = -45° and θrx = 0° were analyzed using HFSS.

[0178] In order to grasp the allowable incident angle range, a similar analysis was performed when the angle was changed in 2° increments within the range of −65°≦θix≦−25°.

[0179] Fig. 29 shows the analysis results of the reflectarray 20 obtained in Example A6. In Fig. 29, the horizontal axis represents the reflection angle θrx, and the vertical axis represents the RCS. In the reflectarray 20 of Example A6, the electromagnetic wave incident at θix = -45° was reflected in the desired direction of θrx = 0°, and the RCS was -6.86 dBsm.

[0180] (Comparative Example A6) A reflectarray similar to the reflectarray described in Example A6 was prepared except for the incident angle θix and the reflection angle θrx. The incident angle θix and the reflection angle θrx were set to θix = 0° and θrx = -45°, respectively. The reflection characteristics of the reflectarray 20 were analyzed using HFSS.

[0181] In order to grasp the allowable incident angle range, a similar analysis was performed when the angle was changed in 2° increments within the range of −20°≦θix≦20°.

[0182] 30 shows the analysis results of the reflectarray 20 obtained in Comparative Example A6. In the reflectarray 20 of Comparative Example A6, the electromagnetic wave incident at θix=0° was reflected in the desired direction of θrx=−45°, and the RCS was −6.94 dBsm.

[0183] FIG. 31 shows the results of comparing the amount of change in power that can be received at a specific reflection angle θrx when the incident angle is changed in Example A6 and Comparative Example A6.

[0184] 31, the acceptable incident angle range was 6.1° for Example A6 and 4.2° for Comparative Example A6. As a result of confirming ease of installation, in Example A6, even when the reflectarray was moved 45 cm, the change in received power was within -3 dB in the direction of the receiving angle that satisfied formula (1), whereas in Comparative Example A6, the change was greater than -3 dB. Furthermore, as a result of confirming reception stability, in Example A6, the received power was stable in a range where the acceptable incident angle range was greater than 5.5°, whereas in Comparative Example A6, the received power was unstable in a range where the acceptable incident angle range was 5.5° or less.

[0185] (Example A7) A reflect array 20 having a basic configuration was constructed using copper with a thickness of 0.018 mm for the element pattern 1 and the ground layer 3, and a fluororesin material with a thickness of 0.200 mm for the dielectric layer 2. However, the conductivity of copper was set to 5.8 × 10 siemens / m, the real part of the relative dielectric constant of the dielectric layer 2 was set to 2.06, and tan δ was set to 0.0007.

[0186] The operating frequency was set to 60 GHz, the target reflection characteristics (desired reflection characteristics) were set to θix = −70°, θrx = 0°, and θiy = θry = 0°, and the size Lx of reflection control area 5 in the x-axis direction was determined to be 5.316 mm using equation (3).

[0187] The number of divisions of reflection control region 5 was set to 3, and the size of the unit cell in the x-axis direction and the y-axis direction was set to 1.772 mm. The shape of the element pattern was a cross patch in which two square patches intersected at right angles in the xy plane. Here, the element lengths and element widths were different in each element pattern in reflection control region 5, and the element lengths and element widths in the x-axis direction and the y-axis direction were set to be the same within the same element pattern. Specifically, the element lengths were set to lx1 = ly1, lx2 = ly2, and lx3 = ly3, and the element widths were set to wx1 = wy1, wx2 = wy2, and wx3 = wy3.

[0188] The reflection phase of the unit cell for each element width w and element length l was analyzed using finite element analysis software (HFSS) manufactured by Ansys. It was confirmed that the reflection phase changed as the element width w or element length l changed.

[0189] Next, based on the analysis results of the reflection phase of the unit cell obtained above, the element length l of each unit cell was determined so as to follow the impedance distribution of equation (9). The element lengths l were set to lx1 = ly1 = 1.310 mm, lx2 = ly2 = 1.570 mm, and lx3 = ly3 = 1.459 mm, and the element widths were set to wx1 = wy1 = 1.100 mm, wx2 = wy2 = 1.100 mm, and wx3 = wy3 = 1.100 mm, respectively.

[0190] The reflectarray 20 had 8 x 6 reflection control areas arranged in the x-axis and y-axis directions, and its size in the xy plane was 42.528 mm x 10.632 mm. The reflection characteristics when polarized waves parallel to the y-axis were irradiated onto the reflectarray 20 at θix = -70° and θrx = 0° were analyzed using HFSS.

[0191] In order to grasp the allowable incident angle range, a similar analysis was performed when the angle was changed in 2° increments within the range of −90°≦θix≦−50°.

[0192] Fig. 32 shows the analysis results of the reflectarray 20 obtained in Example A7. In Fig. 32, the horizontal axis represents the reflection angle θrx, and the vertical axis represents the RCS. In the reflectarray 20 of Example A7, the electromagnetic wave incident at θix = -70° was reflected in the desired direction of θrx = 0°, and the RCS was -8.84 dBsm.

[0193] (Comparative Example A7) A reflectarray similar to the reflectarray described in Example A7 was prepared except for the incident angle θix and the reflection angle θrx. The incident angle θix and the reflection angle θrx were set to θix = 0° and θrx = -70°, respectively. The reflection characteristics of the reflectarray 20 were analyzed using HFSS.

[0194] In order to grasp the allowable incident angle range, a similar analysis was performed when the angle was changed in 2° increments within the range of −20°≦θix≦20°.

[0195] 33 shows the analysis results of the reflectarray 20 obtained in Comparative Example A7. In the reflectarray 20 of Comparative Example A7, the electromagnetic wave incident at θix=0° was reflected in the desired direction of θrx=−70°, and the RCS was −8.89 dBsm.

[0196] FIG. 34 shows the results of comparing the amount of change in power that can be received at a specific reflection angle θrx when the incident angle is changed in Example A7 and Comparative Example A7.

[0197] From the results of Figure 34, the acceptable incident angle range was 15.1° for Example A7 and 5.4° for Comparative Example A7. As a result of confirming the ease of installation, in Example A7, even when the reflectarray was moved 45 cm, the change in received power was within -3 dB in the direction of the receiving angle that satisfied formula (1), whereas in Comparative Example A7, the change was greater than -3 dB. Furthermore, as a result of confirming the reception stability, in Example A7, the received power was stable in a range where the acceptable incident angle range was greater than 5.5°, whereas in Comparative Example A7, the received power was unstable in a range where the acceptable incident angle range was 5.5° or less.

[0198] Comparisons between Example A1 (Comparative Example A1) and Example A6 (Comparative Example A6), and between Example A4 (Comparative Example A4) and Example A5 (Comparative Example A5), and Example A7 (Comparative Example A7) revealed that there is no significant difference in the allowable incident angle range depending on the frequency.

[0199] The influence of the reflection angle was confirmed using Example A8 and Comparative Example A8. (Example A8) A reflectarray 20 having a basic configuration was constructed using copper with a thickness of 0.018 mm for the element pattern 1 and the ground layer 3, and a glass / fluororesin composite material with a thickness of 0.764 mm for the dielectric layer 2. However, the conductivity of copper was set to 5.8 × 10 siemens / m, the real part of the relative dielectric constant of the dielectric layer 2 was set to 2.6, and tan δ was set to 0.0025.

[0200] The operating frequency was set to 28 GHz, the target reflection characteristics (desired reflection characteristics) were set to θix = 70°, θrx = -30°, and θiy = θry = 0°, and the size Lx of the reflection control area 5 in the x-axis direction was determined to be 24.348 mm using equation (3).

[0201] The number of divisions of reflection control region 5 was set to 6, and the size of the unit cell in the x-axis direction and the y-axis direction was set to 4.058 mm. The shape of the element pattern was a cross patch in which two square patches were orthogonal to each other in the xy plane. Here, the element length and element width were different in each element pattern in reflection control region 5, and the element length and element width in the x-axis direction and the y-axis direction were the same within the same element pattern. Specifically, the element lengths were set to lx1 = ly1, lx2 = ly2, lx3 = ly3, lx4 = ly4, lx5 = ly5, and lx6 = ly6, and the element widths were set to wx1 = wy1, wx2 = wy2, wx3 = wy3, wx4 = wy4, wx5 = wy5, and wx6 = wy6.

[0202] The reflection phase of the unit cell for each element width w and element length l was analyzed using finite element analysis software (HFSS) manufactured by Ansys. It was confirmed that the reflection phase changed as the element width w or element length l changed.

[0203] Next, based on the analysis results of the reflection phase of the unit cell obtained above, the element length l of each unit cell was determined to follow the impedance distribution of equation (9). The element lengths l were lx1 = ly1 = 2.897 mm, lx2 = ly2 = 3.079 mm, lx3 = ly3 = 3.621 mm, lx4 = ly4 = 1.885 mm, lx5 = ly5 = 2.530 mm, and lx6 = ly6 = 2.743 mm, and the element widths were wx1 = wy1 = 1.500 mm, wx2 = wy2 = 1.500 mm, wx3 = wy3 = 1.500 mm, wx1 = wy1 = 1.500 mm, wx2 = wy2 = 1.500 mm, and wx3 = wy3 = 1.500 mm, respectively.

[0204] The reflectarray 20 had 8 x 6 reflection control areas arranged in the x-axis and y-axis directions, and its size in the xy plane was 194.784 mm x 146.008 mm. The reflection characteristics when polarized waves parallel to the y-axis were irradiated onto the reflectarray 20 at θix = 70° and θrx = -30° were analyzed using HFSS.

[0205] In order to grasp the allowable incident angle range, a similar analysis was performed when the angle was changed in 2° increments within the range of 50°≦θix≦90°.

[0206] Fig. 35 shows the analysis results of the reflectarray 20 obtained in Example A8. In Fig. 35, the horizontal axis represents the reflection angle θrx, and the vertical axis represents the RCS. In the reflectarray 20 of Example A8, the electromagnetic wave incident at θrx = 70° was reflected in the desired direction of θrx = -30°, and the RCS was -1.19 dBsm.

[0207] (Comparative Example A8) A reflectarray similar to the reflectarray described in Example A8 was prepared except for the incident angle θix and the reflection angle θrx. The incident angle θix and the reflection angle θrx were set to θix = -30° and θrx = 70°, respectively. The reflection characteristics of the reflectarray 20 were analyzed using HFSS.

[0208] In order to grasp the allowable incident angle range, a similar analysis was performed when the angle was changed in 2° increments within the range of −20°≦θix≦20°.

[0209] 36 shows the analysis results of the reflectarray 20 obtained in Comparative Example A8. In the reflectarray 20 of Comparative Example A8, the electromagnetic wave incident at θix=−30° was reflected in the desired direction of θrx=70°, and the RCS was −1.86 dBsm.

[0210] FIG. 37 shows the results of comparing the amount of change in power that can be received at a specific reflection angle θrx when the incident angle is changed in each of Example A8 and Comparative Example A8.

[0211] 37, the acceptable incident angle range was 8.3° for Example A8 and 2.5° for Comparative Example A8. As a result of confirming ease of installation, in Example A8, even when the reflectarray was moved 45 cm, the change in received power was within -3 dB in the direction of the receiving angle that satisfied formula (1), whereas in Comparative Example A8, the change was greater than -3 dB. Furthermore, as a result of confirming reception stability, in Example A8, the received power was stable in a range where the acceptable incident angle range was greater than 5.5°, whereas in Comparative Example A8, the received power was unstable in a range where the acceptable incident angle range was 5.5° or less.

[0212] [Embodiment B] Next, we will explain embodiment B. In this embodiment, a "reflectarray unit (electromagnetic wave reflector assembly)" is an assembly of multiple reflectarrays, and is a component that reflects electromagnetic waves in multiple directions, with asymmetric reflection, in which the angle of incidence and the angle of reflection differ, being the main component of the reflected electromagnetic waves.

[0213] [Embodiment B-1] (Configuration of Reflectarray Unit) The configuration of a reflectarray unit 30 according to embodiment B-1 will be described with reference to Figures 38 and 39. Figure 38 is a plan view showing an example of the configuration of the reflectarray unit 30 according to embodiment B-1. Also, Figure 39 is a cross-sectional view showing an example of the configuration of the reflectarray unit 30 according to embodiment B-1. The reflectarray unit 30 is an assembly in which multiple reflectarrays 20 are arranged on a plane, with a unit space between adjacent reflectarrays. By providing a unit space 6 between adjacent reflectarrays 20, asymmetric reflection becomes the main component, and electromagnetic waves can be reflected in multiple other directions.

[0214] More specifically, reflections with a radar scattering cross section (RCS) of -15 dBsm or greater can be obtained at two or more angles excluding the range of ±1 degree of the reference asymmetric reflection, and the RCS of reflections occurring at peak angles other than the peak angle at which the RCS is maximum is within 10 dBsm of the maximum value. This allows electromagnetic waves to be delivered to the entire area even if the blind zone is large, stabilizing communication connections and communication speeds.

[0215] The unit space 6 is preferably an air layer or a resin layer having a dielectric constant of 1 or more and 1.5 or less. If the unit space 6 is made of a conductive material, specular reflection will be mixed in addition to asymmetric reflection, causing unwanted multipath reflection.

[0216] [Embodiment B-2] The configuration of a reflectarray unit 30 according to embodiment B-2 will be described with reference to Figures 40 and 41. Figure 40 is a plan view showing an example of the configuration of a reflectarray unit 30 according to embodiment B-2. Figure 41 is a cross-sectional view showing an example of the configuration of a reflectarray unit 30 according to embodiment B-2. Since the configuration is similar to embodiment B-1 except that multiple reflectarrays 20 are arranged on a support 12 with a unit space 6 sandwiched between them to form the reflectarray unit 30, a detailed description will be omitted. The support 12 is made of a dielectric material such as resin, and a medium with a dielectric constant close to that of air (dielectric constant 1) is preferred. The hardness of the support may be adjusted appropriately depending on the location where the reflectarray unit is to be installed. Setting the support to a predetermined standard size allows for easy transport and attachment to a wide range of components, such as indoor and outdoor building materials, roads, and communication equipment.

[0217] <Example> Figure 42 is a schematic diagram showing an installation example of a reflectarray in the prior art. And Figure 43 is a schematic diagram showing an installation example of a reflectarray in an embodiment of the present invention. Incident waves transmitted from a base station 31 are asymmetrically reflected by a reflectarray unit 30, and the radio waves can be delivered to a radio wave region 34 within a blind zone 33 created by a radio wave shielding object 32. Whereas in the prior art the radio wave region 34 is narrowed (Figure 42), when the reflectarray unit 30 according to an embodiment of the present invention is used, the radio wave region 34 can be widened, and radio waves can be delivered to a wider range of blind zones compared to the prior art.

[0218] Simulations in the examples and comparative examples were performed using the finite element method, and calculations were performed assuming that a plane wave was irradiated onto the reflectarray unit. In a real environment, the base station and the reflectarray unit can be appropriately installed taking into account the distance so that the reflectarray unit is irradiated with a plane wave. Similarly, the distance between the reflectarray unit and the blind zone can also be appropriately installed so that the reflected wave from the reflectarray unit becomes a plane wave. The distance at which a plane wave is formed can be determined using the far-field distance as a guide. For example, if the reflectarray unit is square, where d is the length of one side of the reflectarray unit parallel to the plane formed by the incident wave from the base station and the normal to the reflectarray unit, and λ is the wavelength, then the far-field distance x = 2d ２ / λ. As a specific example, in the case of a reflectarray unit with d = 0.3 m and a base station with a frequency of 4.6 GHz, the reflectarray unit and the base station or blind zone should be separated by 2.76 m or more. However, the above example is only a guideline, and the effect of the present invention cannot be obtained just because the distance between the reflectarray unit and the base station or blind zone is shorter than the far-field distance.

[0219] Examples and comparative examples will be described below. (Comparative Example B1) First, comparative example B1 will be described, which relates to the reflectarray (hereinafter referred to as "unit reflectarray") that constitutes the reflectarray unit that is the subject of the example and serves as the unit when arranging the reflectarrays at a distance. Table B1 shows the configuration data of the unit reflectarray according to comparative example B1. FIG. 44 is a diagram showing a plan view and reflection characteristics of the unit reflectarray according to comparative example B1. FIG. 44(a) is the plan view, and FIG. 44(b) is the reflection characteristics. The cross section of the unit reflectarray according to comparative example B1 is the same as the cross section of the reflectarray 20 in FIG. 39. In the following description, the reference numerals for the same parts will be omitted. A unit reflectarray 20 was constructed using copper with a thickness of 0.018 mm for the element pattern 1 and ground layer 3, and CGP-500 with a thickness of 0.764 mm for the dielectric layer 2. However, the conductivity of copper was set to 5.8 × 10 siemens / m, the real part of the relative dielectric constant of the dielectric layer 2 was set to 2.6, and tan δ was set to 0.0025.

[0220] The operating frequency was set to 27.2 GHz, the target reflection characteristics (desired reflection characteristics) were set to θix = 33°, θrx = 0°, θiy = 0°, and θry = 0°, and the size Lx of the reflection control area 5 in the x-axis direction was determined to be 20.238 mm using equation (1).

[0221] The number of divisions of reflection control region 5 was set to 3, and the size of the unit cell in the x-axis direction and the y-axis direction was set to 6.746 mm. The shape of the element pattern was a cross patch in which two square patches were orthogonal to each other in the xy plane. Here, only the element width differed in each element pattern within reflection control region 5. Specifically, the element length was set to lx1 = lx2 = lx3 = ly1 = ly2 = ly3 = 3.25 mm, and the element widths within the same element pattern were set to wx1 = wy1, wx2 = wy2, and wx3 = wy3. The reflection phase of the unit cell relative to the element width w was analyzed using HFSS. Note that in unit cell p, the element length in the x-axis direction is set to lxp, the element length in the y-axis direction is set to lyp, the element width in the x-axis direction is set to wxp, and the element width in the y-axis direction is set to wyp. However, when lxp and lyp are equal, the subscripts x and y are omitted, when wxp and wyp are equal, the subscripts x and y are omitted, and when the unit cell is not specified, the subscript p may be omitted.

[0222] Next, based on the analysis results of the unit cells, the element width w in each unit cell was determined so as to conform to the impedance distribution of equation (8). The element widths w were set to w1 = 1.582 mm, w2 = 2.955 mm, and w3 = 0.319 mm, respectively.

[0223] 44(a), the reflectarray 20 has 1 × 3 identical reflection control regions 5 arranged in the x-axis and y-axis directions (resulting in 3 × 3 unit cells in the x-axis and y-axis directions), resulting in a size of 20.238 mm square in the xy plane. The reflection characteristics when polarized waves parallel to the x-axis were irradiated onto the reflectarray 20 at θix = 33° and θiy = 0° were analyzed using HFSS.

[0224] 44(b) is a diagram showing the reflection characteristics of the unit reflectarray 20 according to Comparative Example B1. The horizontal axis is the reflection angle θry, and the vertical axis is the RCS (radar cross section). The RCS is a value that substantially corresponds to the intensity of the reflected wave. The electromagnetic wave incident at θix=33° was reflected at its maximum value in the desired direction of θrx=0° (reference asymmetric reflection direction), and the RCS was −19.12 dBsm.

[0225] In evaluating the reflection characteristics of the following examples and comparative examples, as described above, a test piece is deemed to pass if it is possible to obtain a reflection with a radar scattering cross section (RCS) of -15 dBsm or greater at two or more angles excluding the range of ±1 degree from the reference asymmetric reflection, and the RCS of the reflection occurring at a peak angle other than the peak angle at which the RCS is maximum is within 10 dBsm of the maximum value. If the reflection characteristics satisfy the pass criteria, reflected light having a peak of a predetermined intensity is generated in directions other than the reference asymmetric reflection direction, making it possible to broaden the radio wave range 34 with sufficient intensity overall. Comparative Example B1 fails because the peak intensity value in the reference asymmetric reflection direction at which the RCS is maximum does not even reach -15 dBsm.

[0226] (Comparative Example B2) Figure 45 shows a plan view and reflection characteristics of a reflectarray according to Comparative Example B2. Figure 45(a) is a plan view, and Figure 45(b) shows reflection characteristics. As shown in Figure 45(a), Comparative Example B2 is the same as Comparative Example B1, except that it is a reflectarray having a configuration in which 2 x 2 unit reflectarrays 20 are arranged closely together. Furthermore, when analyzed using HFSS, as shown in Figure 45(b), an electromagnetic wave incident at θix = 33° was reflected at its maximum value in the desired θrx = 0° direction (reference asymmetric reflection direction), and the RCS was -6.97 dBsm. In Comparative Example B2, reflected light having a peak at an angle different from the reference asymmetric reflection direction was generated (-18.01 dBsm at -25°), but the difference from the maximum value was greater than 10 dBsm, so it failed.

[0227] (Comparative Example B3) FIG. 46 shows a plan view and reflection characteristics of a reflectarray according to Comparative Example B3. FIG. 46(a) is a plan view, and FIG. 46(b) shows reflection characteristics. As shown in FIG. 46(a), Comparative Example B3 is the same as Comparative Example B1, except that it is a reflectarray having a configuration in which 3 x 3 unit reflectarrays 20 are arranged side by side. Furthermore, when analyzed using HFSS, as shown in FIG. 46(b), an electromagnetic wave incident at θix = 33° was reflected at its maximum value in the desired θrx = 0° direction (reference asymmetric reflection direction), and the RCS was 0.26 dBsm. In Comparative Example B3, reflected light having a peak at an angle different from the reference asymmetric reflection direction was generated (-12.26 dBsm at -15°, -13.01 dBsm at 15°), but both were rejected because the difference from the maximum value was greater than 10 dBsm.

[0228] Next, examples related to reflectarray units will be described. In the following description, the length of the unit space between reflectarrays refers to the average distance of the gap between adjacent reflectarrays arranged at a distance. (Example B1) Figure 47 shows a plan view and reflection characteristics of a reflectarray unit according to Example B1. Figure 47(a) is a plan view, and Figure 47(b) is reflection characteristics. As shown in Figure 47(a), the reflectarray unit 30 according to Example B1 is composed of an assembly of unit reflectarrays arranged with a unit space of 0.5 unit reflectarrays between them, compared to the reflectarray of Comparative Example B2, which is an array of 2 x 2 unit reflectarrays 20. The length of the unit space between each unit reflectarray 20 is 10.119 mm, and the length of one side of the outer shape of the reflectarray unit 30 is 50.595 mm. Some of the incident light irradiated onto the reflect array unit 30 as a plane wave is transmitted through the unit space, but when analyzed using HFSS, as shown in Figure 47 (b), the electromagnetic wave incident at θix = 33° exhibited reflection characteristics in which the reflected light at θrx = 0°, which is the reference asymmetric reflection direction, was split into two reflected lights.

[0229] As shown in Figure 47(b), the peaks of the two reflected lights are seen at an RCS of -8.39 dBsm at -9 degrees and -8.59 dBsm at 9 degrees. Therefore, since there are two or more reflected lights with an RCS peak intensity of -15 dBsm or more at angles excluding the range of ±1 degree from the reference asymmetric reflection direction, and the difference between the maximum value and the other RCSs is within 10 dBsm, the test passes.

[0230] (Example B2) Figure 48 is a diagram showing a plan view and reflection characteristics of a reflectarray unit according to Example B2. Figure 48(a) is a plan view, and Figure 48(b) is the reflection characteristics. As shown in Figure 48(a), the reflectarray unit 30 according to Example B2 is composed of an assembly of unit reflectarrays arranged with a unit space of 0.75 unit reflectarrays, compared to the reflectarray of Comparative Example B2, which is an array of 2 x 2 unit reflectarrays 20. The length of the unit space between each unit reflectarray 20 is 15.1785 mm, and the length of one side of the outer shape of the reflectarray unit 30 is 55.6545 mm. Some of the incident light irradiated onto the reflect array unit 30 as a plane wave is transmitted through the unit space, but when analyzed using HFSS, the reflection characteristics were such that the electromagnetic wave incident at θix = 33° was split into three reflected lights from the reflected light at θrx = 0°, which is the reference asymmetric reflection direction, as shown in Figure 48(b). Note that the characteristics show behavior between the reflection characteristics of Example B1 (Figure 16(b)) and the reflection characteristics of Example B3 (Figure 18(b)) described below.

[0231] As shown in Figure 48(b), the three reflected light peaks are found at RCS of -9.14 dBsm at -12°, -7.26 dBsm at 4°, and -14.63 dBsm at 20°. Therefore, since there are two or more reflected lights with peak intensities of RCS of -15 dBsm or more at angles excluding the range of ±1 degree from the reference asymmetric reflection direction, and the difference between the maximum value and the other RCSs is within 10 dBsm, the test passes.

[0232] (Example B3) Figure 49 is a diagram showing a plan view and reflection characteristics of a reflectarray unit according to Example B3. Figure 49(a) is a plan view, and Figure 49(b) is the reflection characteristics. As shown in Figure 49(a), the reflectarray unit 30 according to Example B3 is composed of an assembly of unit reflectarrays arranged with a unit space of one unit reflectarray between them, as opposed to the reflectarray of Comparative Example B2, which is an array of 2 x 2 unit reflectarrays 20. The length of the unit space between each unit reflectarray 20 is 20.238 mm, and the length of one side of the outer shape of the reflectarray unit 30 is 60.714 mm. Some of the incident light irradiated onto the reflect array unit 30 as a plane wave is transmitted through the unit space portion, but when analyzed using HFSS, the reflection characteristics were such that the electromagnetic wave incident at θix = 33° was split into three reflected lights from the reflected light at θrx = 0°, which is the reference asymmetric reflection direction, as shown in Figure 49(b). In particular, compared to Comparative Example B3, which has the same side length of the outer shape but no unit space, the effect of the presence of the unit space on broadening the reflection characteristics was clearly shown.

[0233] As shown in Figure 49(b), the peaks of the three reflected lights are found at RCS of -9.81 dBsm at -15 degrees, -6.80 dBsm at 0 degrees, and -10.58 dBsm at 14 degrees. Therefore, since there are two or more reflected lights with peak intensities of RCS of -15 dBsm or more at angles excluding the range of ±1 degree from the reference asymmetric reflection direction, and the difference between the maximum value and the other RCSs is within 10 dBsm, the test passes.

[0234] (Example B4) Figure 50 is a diagram showing a plan view and reflection characteristics of a reflectarray unit according to Example B4. Figure 50(a) is a plan view, and Figure 50(b) is the reflection characteristics. As shown in Figure 50(a), the reflectarray unit 30 according to Example B4 is composed of an assembly of unit reflectarrays arranged with a unit space of 1.5 unit reflectarrays, compared to the reflectarray of Comparative Example B2, which is an array of 2 x 2 unit reflectarrays 20. The length of the unit space between each unit reflectarray 20 is 30.357 mm, and the length of one side of the outer shape of the reflectarray unit 30 is 70.833 mm. Some of the incident light irradiated onto the reflect array unit 30 as a plane wave is transmitted through the unit space, but when analyzed using HFSS, the reflection characteristics were such that the electromagnetic wave incident at θix = 33° was split into four reflected lights from the reflected light at θrx = 0°, which is the reference asymmetric reflection direction, as shown in Figure 50(b). Note that the characteristics show behavior between the reflection characteristics of Example B3 (Figure 49(b)) and the reflection characteristics of Example B5 (Figure 20(b)) described below.

[0235] As shown in Figure 50(b), the peaks of the four reflected lights are found at RCS of -11.43 dBsm at -18 degrees, -7.49 dBsm at -6 degrees, -7.59 dBsm at 6 degrees, and -12.53 dBsm at 18 degrees. Therefore, since there are two or more reflected lights with an RCS peak intensity of -15 dBsm or more at angles excluding the range of ±1 degree from the reference asymmetric reflection direction, and the difference between the maximum value and the other RCSs is within 10 dBsm, the test passes.

[0236] (Example B5) Figure 51 is a diagram showing a plan view and reflection characteristics of a reflectarray unit according to Example B5. Figure 51(a) is a plan view, and Figure 51(b) is the reflection characteristics. As shown in Figure 51(a), the reflectarray unit 30 according to Example B5 is composed of an assembly of unit reflectarrays arranged with a unit space of two unit reflectarrays between them, as opposed to the reflectarray of Comparative Example B2, which is an array of 2 x 2 unit reflectarrays 20. The length of the unit space between each unit reflectarray 20 is 40.476 mm, and the length of one side of the outer shape of the reflectarray unit 30 is 80.952 mm. Some of the incident light irradiated onto the reflect array unit 30 as a plane wave is transmitted through the unit space, but when analyzed using HFSS, as shown in Figure 51 (b), the electromagnetic wave incident at θix = 33° exhibited reflection characteristics in which the reflected light at θrx = 0°, which is the reference asymmetric reflection direction, was split into five reflected lights.

[0237] As shown in Figure 51(b), the five reflected light peaks are found at RCS of -13.04 dBsm at -21°, -8.48 dBsm at -10°, -7.00 dBsm at 0°, -8.59 dBsm at 10°, and -14.21 dBsm at 20°. Therefore, since there are two or more reflected lights with an RCS peak intensity of -15 dBsm or more at angles excluding the range of ±1 degree from the reference asymmetric reflection direction, and the difference between the maximum value and the other RCSs is within 10 dBsm, the test passes.

[0238] (Example B6) Figure 52 shows a plan view and reflection characteristics of a reflectarray unit according to Example B6. Figure 52(a) is a plan view, and Figure 52(b) is reflection characteristics. As shown in Figure 52(a), the reflectarray unit 30 according to Example B6 has a configuration in which a unit reflectarray is added to the center of the reflectarray unit according to Example B3, which is configured with a unit space equivalent to one unit reflectarray. Some of the incident light irradiated onto the reflectarray unit 30 as a plane wave is transmitted through the unit space portion. However, when analyzed using HFSS, as shown in Figure 52(b), the reflection direction (peak angle) indicating the peak intensity of the reflected light split into three was almost the same as in Example B3. On the other hand, the RCS at 0° was larger than the value in Example B3, suggesting that reflection from the central unit reflectarray contributes.

[0239] As shown in Figure 52(b), the peaks of the three reflected lights are found at RCS of -12.35 dBsm at -15°, -4.87 dBsm at 0°, and -13.11 dBsm at 15°. Therefore, since there are two or more reflected lights with peak intensities of RCS of -15 dBsm or more at angles excluding the range of ±1 degree from the reference asymmetric reflection direction, and the difference between the maximum value and the other RCSs is within 10 dBsm, the test passes.

[0240] (Example B7) Figure 53 shows a plan view and reflection characteristics of a reflectarray unit according to Example B7. Figure 53(a) is a plan view, and Figure 53(b) is reflection characteristics. As shown in Figure 53(a), the reflectarray unit 30 according to Example B7 has a configuration in which a unit reflectarray is added to the center of the reflectarray unit according to Example B4, which is configured with a unit space equivalent to 1.5 unit reflectarrays. Some of the incident light irradiated onto the reflectarray unit 30 as a plane wave is transmitted through the unit space. However, when analyzed using HFSS, as shown in Figure 53(b), the reflection direction (peak angle) indicating the peak intensity of the reflected light split into four was almost the same as in Example B4. On the other hand, the RCS at angles less than -15° was reduced compared to the value in Example B4, and the RCS at angles greater than 15° tended to increase compared to the value in Example B4.

[0241] As shown in Figure 53(b), the peaks of the four reflected lights are found at RCS of -14.11 dBsm at -18°, -5.53 dBsm at -6°, -10.15 dBsm at 6°, and -10.55 dBsm at 18°. Therefore, since there are two or more reflected lights with an RCS peak intensity of -15 dBsm or more at angles excluding the range of ±1 degree from the reference asymmetric reflection direction, and the difference between the maximum value and the other RCSs is within 10 dBsm, the test passes.

[0242] (Example B8) Figure 54 shows a plan view and reflection characteristics of a reflectarray unit according to Example B8. Figure 54(a) is a plan view, and Figure 54(b) is reflection characteristics. As shown in Figure 54(a), the reflectarray unit 30 according to Example B8 has a configuration in which a unit reflectarray is added to the center of the reflectarray unit according to Example B5, which is configured with a unit space equivalent to two unit reflectarrays. Although some of the incident light irradiated to the reflectarray unit 30 as a plane wave is transmitted through the unit space, when analyzed using HFSS, as shown in Figure 54(b), the reflection direction (peak angle) indicating the peak intensity of the reflected light divided into five was almost the same as in Example B5. On the other hand, the RCS around 0° and ±20° was reduced compared to the value of Example B5, and the RCS around ±10° tended to increase compared to the value of Example B5.

[0243] As shown in Figure 54(b), the five reflected light peaks are -15.68 dBsm RCS at -21 degrees, -6.46 dBsm at -10 degrees, -9.56 dBsm at 0 degrees, -6.1 dBsm at 10 degrees, and -16.82 dBsm at 21 degrees. Therefore, since there are two or more reflected lights with an RCS peak intensity of -15 dBsm or more at angles excluding the range of ±1 degree from the reference asymmetric reflection direction, and the difference between the maximum value and the other RCSs is within 10 dBsm, the test passes.

[0244] (Example B9) Figure 55 is a diagram showing a plan view and reflection characteristics of a reflectarray unit according to Example B9. Figure 55(a) is a plan view, and Figure 55(b) is the reflection characteristics. As shown in Figure 55(a), the reflectarray unit 30 according to Example B9 has an increased number of reflectarrays while leaving a unit space equivalent to one unit reflectarray. The reflectarray unit according to Example B3, which is spaced apart by a unit space equivalent to one unit reflectarray, is arranged in the center, and reflectarrays are arranged at the four corners extending diagonally, spaced apart by one unit reflectarray. The length of one side of the external shape of the reflectarray unit 30 of this example is 141.666 mm. Although some of the incident light irradiated onto the reflect array unit 30 as a plane wave is transmitted through the unit space, when analyzed using HFSS, as shown in Figure 55(b), the reflection directions (peak angles) indicating the peak intensities of the reflected light split into three were almost the same as in Example B3. On the other hand, the RCS at each peak angle tended to increase compared to the value in Example B3.

[0245] As shown in Figure 55(b), the peaks of the three reflected lights are found at RCS of -4.18 dBsm at -16°, -0.78 dBsm at 0°, and -5.00 dBsm at 16°. Therefore, since there are two or more reflected lights with peak intensities of RCS of -15 dBsm or more at angles excluding the range of ±1 degree from the reference asymmetric reflection direction, and the difference between the maximum value and the other RCSs is within 10 dBsm, the test passes.

[0246] (Example B10) Figure 56 is a diagram showing a plan view and reflection characteristics of a reflectarray unit according to Example B10. Figure 56(a) is a plan view, and Figure 56(b) is reflection characteristics. As shown in Figure 56(a), the reflectarray unit 30 according to Example B10 has an increased number of reflectarrays while leaving a unit space equivalent to one unit reflectarray, as in Example B9. Compared to the reflectarray unit according to Example B9, two unit reflectarrays are added to each of the four sides of the outer shape, with a unit space equivalent to one unit reflectarray. The length of one side of the outer diameter of the reflectarray unit 30 according to this example is 141.666 mm. Some of the incident light irradiated onto the reflectarray unit 30 as a plane wave is transmitted through the unit space portion. However, when analyzed using HFSS, as shown in Figure 55(b), the reflection direction (peak angle) indicating the peak intensity of the reflected light split into three was almost the same as in Examples B3 and B9. On the other hand, the RCS at each peak angle tended to be higher than the values ​​of Examples B3 and B9.

[0247] As shown in Figure 55(b), the peaks of the three reflected lights are found at RCS 2.03 dBsm at -16°, 5.33 dBsm at 0°, and 0.99 dBsm at 16°. Therefore, since there are two or more reflected lights with peak intensities of RCS of -15 dBsm or more at angles excluding the range of ±1 degree from the reference asymmetric reflection direction, and the difference between the maximum value and the other RCSs is within 10 dBsm, the test passes.

[0248] (Example B11) Figure 57 shows a plan view and reflection characteristics of a reflectarray unit according to Example B11. Figure 57(a) is a plan view, and Figure 57(b) is reflection characteristics. As shown in Figure 57(a), the reflectarray unit 30 according to Example B11 has a configuration in which the reflectarray unit according to Example B3, which is located at the center, is removed from the reflectarray unit according to Example B9. The length of the unit space between each unit reflectarray 20 is 101.19 mm, and the length of one side of the outline of the reflectarray unit 30 is 141.666 mm. Although some of the incident light irradiated onto the reflectarray unit 30 as a plane wave is transmitted through the unit space, analysis using HFSS showed a tendency for a large number of reflected lights with approximately the same peak intensity to be generated, rather than being divided into reflected lights with significant peak intensities as in Examples B3, B9, and B10, as shown in Figure 57(b).

[0249] As shown in Figure 57(b), the three reflected light peaks corresponding to Examples B3, B9, and B10 are found at RCS of -10.29 dBsm at -16°, -6.90 dBsm at 0°, and -11.05 dBsm at 16°. Therefore, since there are two or more reflected lights with an RCS peak intensity of -15 dBsm or more at angles excluding the range of ±1 degree from the reference asymmetric reflection direction, and the difference between the maximum value and the other RCSs is within 10 dBsm, the test passes.

[0250] (Example B12) Figure 58 is a diagram showing a plan view and reflection characteristics of a reflectarray unit according to Example B12. Figure 58(a) is a plan view, and Figure 58(b) is reflection characteristics. As shown in Figure 58(a), the reflectarray unit 30 according to Example B12 is configured by combining and arranging two reflectarray units of Example B1, each spaced apart by a unit space of 0.5 unit reflectarrays, in the second and fourth quadrants of the xy plane, and two reflectarray units of Example B3, each spaced apart by a unit space of one unit reflectarray, in the first and third quadrants of the xy plane, with a unit space of one unit reflectarray between them. Some of the incident light irradiated onto the reflectarray unit 30 as a plane wave is transmitted through the unit space portions, but when analyzed using HFSS, it was found that the reflection characteristics were a superposition of the reflection characteristics of Example B1 and Example B3, as shown in Figure 58(b).

[0251] As shown in Figure 58(b), the three reflected light peaks corresponding to Examples B3, B9, and B10 are found at RCS 0.52 dBsm at -15°, -0.68 dBsm at 0°, and -0.14 dBsm at 14°. Therefore, since there are two or more reflected lights with an RCS peak intensity of -15 dBsm or more at angles excluding the range of ±1 degree from the reference asymmetric reflection direction, and the difference between the maximum value and the other RCSs is within 10 dBsm, the test passes.

[0252] An example of embodiment B-2 including a support 12 will be described below. (Example B13) Figure 59 shows a plan view, a cross-sectional view, and reflection characteristics of a reflectarray unit according to Example B13. Figure 59(a-1) is a plan view, Figure 59(a-2) is a cross-sectional view, and Figure 59(b) is reflection characteristics. As shown in Figures 59(a-1) and (a-2), the reflectarray unit 30 according to Example B13 has a configuration in which the reflectarray unit of Example B3, which is spaced apart by a unit space equivalent to one unit reflectarray, is arranged on a support 12. The support 12 is made of Styrofoam made of polystyrene, and has a thickness of 30 mm, a dielectric constant ε' = 1.02, and tan δ = 0. The configuration other than the support is the same as that of Example B3. Some of the incident light irradiated onto the reflect array unit 30 as a plane wave passes through the unit space and the support, but when analyzed using HFSS, as shown in Figure 59 (b), the reflection characteristics such as the reflection direction (peak angle) and RCS, which indicate the peak intensity of the reflected light split into three, were almost unchanged from those in Example B3.

[0253] As shown in Figure 59(b), the peaks of the three reflected lights are found at RCS of -9.71 dBsm at -15 degrees, -6.41 dBsm at 0 degrees, and -10.39 dBsm at 14 degrees. Therefore, since there are two or more reflected lights with peak intensities of RCS of -15 dBsm or more at angles excluding the range of ±1 degree from the reference asymmetric reflection direction, and the difference between the maximum value and the other RCSs is within 10 dBsm, the test passes.

[0254] (Example B14) Figure 60 is a diagram showing a plan view, a cross-sectional view, and reflection characteristics of a reflectarray unit according to Example B14. Figure 60(a-1) is a plan view, Figure 60(a-2) is a cross-sectional view, and Figure 60(b) is reflection characteristics. As shown in Figures 60(a-1) and (a-2), the reflectarray unit 30 according to Example B14 has a configuration in which the reflectarray units of Example B3, each spaced apart by a unit space equivalent to one unit reflectarray, are arranged on a support 12. The support 12 is an acrylic plate made of acrylic, with a thickness of 30 mm, a dielectric constant ε' = 3.3, and tan δ = 0. The configuration other than the support is the same as that of Example B3. Some of the incident light irradiated onto the reflect array unit 30 as a plane wave passes through the unit space portion and the support body. When analyzed using HFSS, as shown in Figure 60(b), the reflection direction (peak angle) indicating the peak intensity of the reflected light split into three was almost the same as in Example B3, but the peak intensity in the reference asymmetric reflection direction (0°) decreased and the RCS in the specular reflection direction (33°) increased, indicating a tendency for reflection to dissipate overall.

[0255] As shown in Figure 60(b), the three reflected light peaks are found at RCS of -6.91 dBsm at -15°, -7.42 dBsm at -1°, and -11.51 dBsm at 14°. Therefore, since there are two or more reflected lights with peak intensities of RCS of -15 dBsm or more at angles excluding the range of ±1 degree from the reference asymmetric reflection direction, and the difference between the maximum value and the other RCSs is within 10 dBsm, the test passes.

[0256] (Example B15) Figure 61 is a diagram showing a plan view, a cross-sectional view, and reflection characteristics of a reflectarray unit according to Example B15. Figure 61(a-1) is a plan view, Figure 61(a-2) is a cross-sectional view, and Figure 61(b) is the reflection characteristics. As shown in Figures 61(a-1) and (a-2), the reflectarray unit 30 according to Example B15 has a configuration in which the reflectarray units of Example B3, each spaced apart by a unit space equivalent to one unit reflectarray, are arranged on a support 12. The support 12 is made of Styrofoam made of polystyrene, and has a thickness of 5 mm, a dielectric constant ε' = 1.02, and tan δ = 0. The configuration other than the support is the same as that of Example B3. Some of the incident light irradiated onto the reflect array unit 30 as a plane wave passes through the unit space and the support, but when analyzed using HFSS, as shown in Figure 61 (b), the reflection characteristics such as the reflection direction (peak angle) and RCS, which indicate the peak intensity of the reflected light split into three, were almost unchanged from those in Example B3.

[0257] As shown in Figure 61(b), the peaks of the three reflected lights are found at RCS of -9.48 dBsm at -15 degrees, -6.39 dBsm at 0 degrees, and -10.57 dBsm at 14 degrees. Therefore, since there are two or more reflected lights with peak intensities of RCS of -15 dBsm or more at angles excluding the range of ±1 degree from the reference asymmetric reflection direction, and the difference between the maximum value and the other RCSs is within 10 dBsm, the test passes.

[0258] (Example B16) Figure 62 is a diagram showing a plan view, a cross-sectional view, and reflection characteristics of a reflectarray unit according to Example B16. Figure 62(a-1) is a plan view, Figure 62(a-2) is a cross-sectional view, and Figure 62(b) is reflection characteristics. As shown in Figures 62(a-1) and (a-2), the reflectarray unit 30 according to Example B16 has a configuration in which the reflectarray units of Example B3, each spaced apart by a unit space equivalent to one unit reflectarray, are arranged on a support 12. The support 12 is an acrylic plate made of acrylic, with a thickness of 5 mm, a dielectric constant ε' = 3.3, and tan δ = 0. The configuration other than the support is the same as that of Example B3. Some of the incident light irradiated onto the reflect array unit 30 as a plane wave passes through the unit space portion and the support body, but when analyzed using HFSS, as shown in Figure 62(b), the reflection direction (peak angle) indicating the peak intensity of the reflected light divided into three was almost the same as in Example B3, but there was a tendency for the reflection to dissipate overall, with the peak intensity in the reference asymmetric reflection direction (0°) decreasing and the RCS in the specular reflection direction (33°) increasing.

[0259] As shown in Figure 62(b), the three reflected light peaks are found at RCS of -9.49 dBsm at -15°, -5.99 dBsm at -1°, and -9.91 dBsm at 14°. Therefore, since there are two or more reflected lights with peak intensities of RCS of -15 dBsm or more at angles excluding the range of ±1 degree from the reference asymmetric reflection direction, and the difference between the maximum value and the other RCSs is within 10 dBsm, the test passes.

[0260] (Discussion) In the above examples, when a unit space for p reflectarrays is referred to, it actually means p times the length of the reflection control region included in the reflectarray (however, the length of the reflection control region means the length (Lx) in the direction in which multiple unit cells included in the reflection control region are aligned). Therefore, according to the results of the examples, for a reflectarray unit in which the length of the unit space is 0.75 (3 / 4) of the length of the reflection control region, reflected light with sufficient peak intensity is generated so as to split before and after the reflection angle in the reference asymmetric reflection direction, thereby realizing a wider area. Therefore, a similar effect can be achieved if the length is at least 1 / 3 of the length of the reflection control region. Furthermore, as the length of the unit space increases, there is a tendency for the number of reflected light beams split before and after the reference asymmetric reflection direction to increase, making it possible to deliver reflected waves over a wider area.

[0261] In particular, when the length of the unit space is n times (n is a natural number) the length of the reflection control region, reflected light having a peak intensity is generated in the same direction as the reference asymmetric reflection direction, which is preferable because it makes design easier (Examples B3 and B5).In contrast, when the length of the unit space is (n+1 / 2) times (n is 0 or a natural number) the length of the reflection control region, reflected light having a peak intensity is not generated in the reference asymmetric reflection direction, and reflected light having approximately the same peak intensity tends to be generated at angles before and after that (B1 and B4).

[0262] When the length of the unit space is n times (n is a natural number) the length of the reflection control area, and a reflectarray is placed at the center of the reflectarray unit in addition to the reflectarrays at the four corners of the square arrangement, the peak intensity in the reference asymmetric reflection direction may increase (Example B6).

[0263] When the number of reflectarrays arranged was increased while keeping the length of the unit space constant, the peak reflection intensity tended to increase as the number of reflectarrays increased (Examples B9 and B10).

[0264] The reflection characteristics of a reflectarray unit configured by mixing and arranging reflectarray units with unit space lengths of different lengths is a superposition of the reflection characteristics of each of the constituent reflectarrays (Example B12).

[0265] In the case of a reflectarray unit having a support, if the dielectric constant of the support is a high value of about 3.3, the reflection characteristics show a tendency for the peak intensity in the reference asymmetric reflection direction to decrease and the RCS in the specular reflection direction to increase, resulting in an overall tendency for reflection to dissipate, so the dielectric constant is preferably between 1 and 1.5 (Examples B13 to B16). Furthermore, any dielectric such as a resin with a dielectric constant within this numerical range can be used as the material to fill the unit space.

[0266] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and examples, and various modifications are possible without departing from the spirit of the present invention. It is also possible to combine embodiments. For example, in embodiment B, the configuration of the unit reflectarray is not limited to the examples of the element pattern, unit cell, reflection control region, etc. described in comparative example B1. Furthermore, the reflectarray unit is not necessarily limited to arranging multiple reflectarrays on a plane, and they can also be arranged on a curved surface within the spirit of the present invention.

[0267] The following are non-limiting examples of aspects that may be included in the present invention. (Aspect 1) A reflectarray including an element pattern, a dielectric layer, and a ground layer, and arranged in one or more locations, and having a wide range of incident angles or reflection angles for electromagnetic waves that provide good communication. (Aspect 2) The reflectarray according to Aspect 1 has a reflection control region that controls a phase, and the reflection control region satisfies the following formula (1) when the length of a long side is L, the wavelength of the reflected electromagnetic wave is λ, the incident angle is θi, and the reflection angle is θr, where |θi| is in the range of 45° to 70°, and the incident angle θi and the reflection angle θr satisfy the relationship of the following formula (2), and the allowable incident angle range Δθi is in the range of more than 5.5° and not more than 16°. (Aspect 3) The reflectarray according to Aspect 1 or 2, wherein the element pattern has a cross patch structure. (Aspect 4) The reflectarray according to any one of Aspects 1 to 3, wherein the reflectarray reflects electromagnetic waves of 3 GHz to 60 GHz. (Aspect 5) An electromagnetic wave reflecting system in which an electromagnetic wave primarily radiated from a transmitter hits the reflectarray and an electromagnetic wave secondarily radiated from the reflectarray is delivered to a receiver, wherein the reflectarray is the reflectarray according to any one of Aspects 1 to 4. (Aspect 6) A method for installing a reflectarray that reflects electromagnetic waves, wherein the reflectarray has a reflection control region that controls a phase, and the reflection control region satisfies the following formula (1) when the length of the long side is L, the wavelength of the electromagnetic wave to be reflected is λ, the incident angle is θi, and the reflection angle is θr, and the reflectarray is fixed to a support such that the incident angle θi is in the range of 45° or more and 70° or less, and the incident angle θi and the reflection angle θr satisfy the relationship of the following formula (2). (Aspect 7) The installation method of a reflectarray according to Aspect 6, wherein the reflectarray is the reflectarray according to any one of Aspects 1 to 4. (Aspect 8) The reflectarray unit according to any one of Aspects 1 to 3, wherein the plurality of arranged reflectarrays (hereinafter referred to as "reflectarray units") are characterized in that a unit space exists between the reflectarrays, the reflectarrays include at least one reflection control area, and the reflection control area is the same in all of the reflectarrays. (Aspect 9) The reflectarray unit according to Aspect 8, wherein the length of the unit space is one-third or more of the length of the reflection control area. (Aspect 10) The reflectarray unit according to Aspect 8 or 9, wherein the length of the unit space is a natural number multiple of the length of the reflection control area. (Aspect 11) The reflectarray unit according to any one of Aspects 8 to 10, wherein the lengths of the unit spaces are all the same. (Aspect 12) The reflectarray unit according to any one of Aspects 8 to 11, characterized in including a reflectarray arranged in the center in addition to the reflectarrays arranged at the four corners of a square. (Aspect 13) The reflectarray unit according to any one of Aspects 8 to 11, characterized in that the reflectarrays are arranged on a support. (Aspect 14) The reflectarray unit according to Aspect 13, characterized in that the support has a relative dielectric constant of 1 or more and 1.5 or less. (Aspect 15) The reflectarray unit according to any one of Aspects 8 to 14, characterized in that, within the reflection control region, a first element width wx that is the width of the element pattern in the x-axis direction and / or a second element width wy that is the width of the element pattern in the y-axis direction differs for each of the element patterns arranged in at least two unit cells.

[0268] 1, 1a-1c, 1 １ -1 ｎ , 1 ｘ １ -1 ｘ ｎ , 1 ｙ１ -1 ｙ ｎ : Element pattern, 2: Dielectric layer, 3: Ground layer, 4, 4a-4f, 4 １ -4 ｎ , 4 ｘ １ -4 ｘ ｎ , 4 ｙ １ -4 ｙ ｎ : unit cell, 5, 5a-5c, 5x, 5y: reflection control region, 6: unit space, 7: functional layer, 8: protective layer, 9: adhesive layer, 10: design layer, 11: installation layer, 12: support, 20, 20a-20h, 20 １ , 20 ２ : Reflectarray, 30: Reflectarray unit, 31: Base station, 32: Radio wave shield, 33: Blind zone, 34: Radio wave area, 200, 201: Wall, 300: Transmitter, 400: Receiver, 500: Shield, 501: Building (shield), 600: Support, 601: Support position adjustment jig

Claims

1. A reflectarray that includes an element pattern, a dielectric layer, and a ground layer, and is arranged in one or more configurations to provide a wide range of incidence angles or reflection angles of electromagnetic waves that enable good communication.

2. The reflect array according to claim 1, wherein the reflect array has a reflection control region that controls a phase, and the reflection control region satisfies the following formula (1) when the length of the long side is L, the wavelength of the reflected electromagnetic wave is λ, the incident angle is θi, and the reflection angle is θr, and the incident angle |θi| is in the range of 45° or more and 70° or less, and the incident angle θi and the reflection angle θr satisfy the relationship of the following formula (2), and the allowable incident angle range Δθi is in the range of more than 5.5° and less than 16°.

3. The reflect array according to claim 2, wherein the element pattern is a cross patch.

4. The reflectarray according to any one of claims 1 to 3, wherein the reflectarray reflects electromagnetic waves of 3 GHz to 60 GHz.

5. An electromagnetic wave reflecting system in which an electromagnetic wave primarily radiated from a transmitter is incident on the reflectarray and an electromagnetic wave secondarily radiated from the reflectarray is received by a receiver, wherein the reflectarray is a reflectarray according to any one of claims 1 to 3.

6. A method for installing a reflectarray that reflects electromagnetic waves, wherein the reflectarray has a reflection control area that controls the phase, and the reflection control area satisfies the following formula (1) when the length of the long side is L, the wavelength of the reflected electromagnetic wave is λ, the incident angle is θi, and the reflection angle is θr, and the reflectarray is fixed to a support so that the incident angle θi is in the range of 45° or more and 70° or less, and the incident angle θi and the reflection angle θr satisfy the relationship of the following formula (2).

7. A method for installing a reflectarray as described in claim 6, wherein the reflectarray is the reflectarray as described in claim 2.

8. The reflectarray unit of claim 1, characterized in that the multiple reflectarrays (hereinafter referred to as "reflectarray unit") have a unit space between them, the reflectarrays include at least one reflection control area, and the reflection control area is the same in all of the reflectarrays.

9. The reflect array unit according to claim 8, wherein the length of the unit space is 1 / 3 or more of the length of the reflection control area.

10. The reflect array unit according to claim 8, wherein the length of the unit space is a natural number multiple of the length of the reflection control area.

11. The reflect array unit according to any one of claims 8 to 10, wherein the unit spaces have the same length.

12. A reflectarray unit according to any one of claims 8 to 10, comprising, in addition to the reflectarrays arranged at the four corners of a square, a reflectarray arranged in the center.

13. A reflect array unit according to any one of claims 8 to 10, characterized in that the reflect array is disposed on a support.

14. The reflect array unit according to claim 13, wherein the relative dielectric constant of the support is 1 or more and 1.5 or less.

15. A reflect array unit described in any one of claims 8 to 10, characterized in that the shape of the element pattern includes a cross patch, and within the reflection control region, a first element width wx which is the width of the element pattern in the x-axis direction and / or a second element width wy which is the width in the y-axis direction differs for each of the element patterns arranged in at least two unit cells.

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