Radio wave scatterers

Abstract

To provide a radio wave scattering body capable of reducing a dead area of a radio wave.SOLUTION: A radio wave scattering body 100 that scatters a radio wave, comprises: a base part 1 which has a rectangular flat shape; and a plurality of flat plate parts 2 that is alternately adjacently arranged to one surface of the base part 1 to scatter the radio wave. Each width of the plurality of flat plate parts 2 is alternately the same. Each thickness of the plurality of flat plate parts 2 is defined on the basis of a predetermined arithmetic formula. The predetermined arithmetic formula is defined by a scattering pattern of the radio wave scattering body 100 defined on the basis of the fact that the plurality of flat plate parts 2 is defined as a radiation element of an array antenna and a condition that the radio wave reflected by the plurality of flat plate parts 2 is enhanced by an interference, and at least indicates a relationship of a magnetic field value of the radio wave, scattered by the radio wave scattering body 100 in each diffraction order and a phase amount corresponded to each thickness of the plurality of flat plate parts 2.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a radio wave scatterer. [Background technology]

[0002] Conventionally, a technique for improving the indoor wireless communication environment by placing a radio wave absorber indoors has been known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-261283 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, when radio waves in a relatively high frequency band are used for wireless communication, it is expected that the directionality of the radio waves is relatively strong, making it more likely that radio wave dead zones (areas where radio waves at a level that allows wireless communication cannot reach) will occur, and there has been a demand for technology to eliminate radio wave dead zones.

[0005] The present invention has been made in view of the above circumstances, and has as its object to provide a radio wave scatterer that can reduce radio wave blind zones. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the radio wave scatterer according to claim 1 is a radio wave scatterer that scatters radio waves, and comprises a plurality of plate-like portions that are arranged adjacent to each other, the plurality of plate-like portions scattering radio waves, the widths of the plurality of plate-like portions being the same, and the thicknesses of the plurality of plate-like portions being determined based on a predetermined arithmetic expression, the predetermined arithmetic expression being determined based on a scattering pattern of the radio wave scatterer that is determined based on the plurality of plate-like portions being regarded as radiating elements of an array antenna, and on a condition where radio waves reflected by the plurality of plate-like portions constructively interfere with each other, and the predetermined arithmetic expression at least indicates the relationship between the electric field value of the radio waves scattered by the radio wave scatterer in each diffraction order and a phase amount corresponding to the thickness of the plurality of plate-like portions. the plurality of plate-like portions are provided in a plurality of units, with K (K is an integer of 2 or more) plate-like portions adjacent to each other being defined as one unit, and the plurality of plate-like portions are periodically arranged in each of the plurality of units; the predetermined arithmetic expression is the following mathematical expression:

number

[0007] The radio wave scatterer according to claim 2 is the radio wave scatterer according to claim 1, The thicknesses of the plurality of plate-like portions are determined based on the δk calculated based on the predetermined arithmetic formula by setting all of the Esum(m) values ​​to be equal to each other, and the determined δk and the frequency of the radio wave.

[0008] The radio wave scatterer according to claim 3 is 1 to In the radio wave scatterer described above, The thicknesses of the plurality of plate-like portions are determined based on the δk calculated based on the predetermined arithmetic formula by setting Esum(m) to 0 when the diffraction order m is 0, and by setting all Esum(m) to be equal to each other when m is other than 0, and then based on the calculated δk and the frequency of the radio wave.

[0009] The radio wave scatterer according to claim 4 is In the radio wave scatterer described in any one of items 1 to 3, the plurality of plate-like portions are made of metal. [Effects of the Invention]

[0010] According to the radio wave scatterer of claim 1, by providing a plurality of plate-like portions that scatter radio waves, it is possible to scatter radio waves, for example, and thereby reduce radio wave blind zones. Furthermore, by determining the thicknesses of the plurality of plate-like portions based on a predetermined calculation formula, for example, the thicknesses of the plurality of plate-like portions can be easily determined, and therefore the radio wave scatterer can be easily designed. Furthermore, multiple units are provided, each unit consisting of K (K is an integer of 2 or more) plate-like parts that are adjacent to each other and are arranged periodically in each of the multiple units. For example, when radio waves are incident on this radio wave scatterer, diffracted waves are generated, and the radio waves can be scattered. Furthermore, since the predetermined arithmetic expression is the arithmetic expression of Mathematical Formula 1, it becomes possible to easily determine the thickness of the plate-like portion based on a relatively simple arithmetic expression, for example.

[0011] Claim 4 According to the radio wave scatterer described above, the multiple plate-like portions are made of metal, which, for example, can suppress attenuation of radio waves in the radio wave scatterer, making it possible to scatter radio waves while maintaining the level of the radio waves incident on the radio wave scatterer. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram showing an installation state of a radio wave scatterer according to an embodiment of the present invention; [Figure 2] FIG. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] FIG. 5 is an enlarged view of a portion of FIG. [Figure 6] FIG. 10 is a diagram showing an arithmetic formula for determining the thickness of a flat plate portion. [Figure 7] FIG. 10 is a diagram illustrating an example of characters for explaining a radio wave scatterer. [Figure 8] 10A and 10B are diagrams for explaining a method for determining the thickness of a flat plate portion. [Figure 9] FIG. 1 is a diagram relating to radio waves scattered by a radio wave scatterer. [Figure 10] FIG. 1 is a diagram relating to radio waves scattered by a radio wave scatterer. [Figure 11] FIG. 1 is a diagram relating to radio waves scattered by a radio wave scatterer. DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of radio wave scatterers according to the present invention will be described in detail with reference to the accompanying drawings.

[0016] [I] Basic Concept of the Embodiment First, the basic concept of the embodiment will be described. The embodiment relates to a radio wave scatterer. The radio wave scatterer according to the present invention is an object that scatters radio waves. The installation position of this radio wave scatterer is arbitrary, and it can be installed, for example, indoors or outdoors.

[0017] [II] Specific details of the embodiment Next, specific details of the embodiment will be described.

[0018] (Configuration - radio wave scatterer) FIG. 1 is a diagram showing the installation state of the radio wave scatterer, FIG. 2 is a perspective view of the radio wave scatterer, FIGS. 3 and 4 are front views of the radio wave scatterer, and FIG. 5 is an enlarged view of a part of FIG. 4.

[0019] It should be noted that Fig. 1 shows a simplified view of the interior of a room in which the radio wave scatterer 100 is installed. In Fig. 4 and Fig. 5, auxiliary lines for explaining the radio wave scatterer are shown as thin lines for the sake of convenience.

[0020] In addition, the X, Y, and Z axes in each figure are assumed to be perpendicular to each other, with the Z axis indicating the height direction of the radio wave scatterer 100 (thickness direction of each flat plate portion 2), the X axis indicating the direction in which multiple flat plate portions 2 are arranged (width direction of each flat plate portion 2), and the Y axis indicating the direction in which each flat plate portion 2 extends (length direction of each flat plate portion 2).

[0021] The radio wave scatterer 100 is an object that scatters radio waves when irradiated with the radio waves, and for example, reflects and scatters the radio waves at angles other than the angle of incidence of the radio waves onto the radio wave scatterer 100. The radio wave scatterer 100 has, for example, an uneven pattern on its surface (+Z direction), and is used by being installed on, for example, a ceiling as shown in FIG.

[0022] Although not shown in Fig. 1, it is assumed that a communication device that transmits and receives radio waves for wireless communication in a predetermined frequency band (for example, the 28 GHz band corresponding to 5G communication) is installed in the room in Fig. 1. The radio waves transmitted from this communication device are scattered by the radio wave scatterer 100 and reach a relatively wide area, making it possible to reduce radio wave blind zones (areas where radio waves at a level that allows wireless communication do not reach).

[0023] Furthermore, the installation position of the radio wave scatterer 100 is not limited to the ceiling, and it may be installed at any position including, for example, a wall, a floor, or the like.

[0024] The radio wave scatterer 100 includes, for example, a base 1 and a plurality of flat plate portions 2 as shown in FIGS.

[0025] (Composition - Radio wave scatterer - Base) The base 1 is a portion on which multiple flat plate portions 2 are arranged, and has, for example, a rectangular flat plate shape. Multiple flat plate portions 2 are fixed and arranged on one surface (+Z direction) of the base 1, and the other surface (-Z direction) is attached to the ceiling of a room (Fig. 1). As shown in Fig. 3, one surface of the base 1 is a flat surface with no irregularities and at the same height, that is, a plane parallel to the XY plane. The material of the base 1 is arbitrary, and may be, for example, metal or resin.

[0026] (Composition - Radio wave scatterer - Flat plate part) The flat plate portion 2 forms an uneven pattern that scatters radio waves, and is, for example, a plurality of plate-like portions (plate-like portions) arranged adjacent to each other as shown in FIG. 3, that scatter radio waves. Each flat plate portion 2 has a predetermined thickness (thickness) and a predetermined width, and is shaped to extend in the longitudinal direction (Y-axis direction). The widths of the plurality of flat plate portions 2 are the same. The thickness of each flat plate portion 2 is determined based on a predetermined calculation formula. The determination of the thickness of each flat plate portion 2 will be described later.

[0027] The material of the flat plate portion 2 is arbitrary, and it may be made of, for example, metal, resin, or other material. In this embodiment, however, from the viewpoint of suppressing attenuation of radio waves in the flat plate portion 2, an example will be described in which the flat plate portion 2 is a metal plate made of metal.

[0028] The multiple flat plate portions 2 are configured in unit units based on thickness, and may be configured as only one unit or as multiple units (i.e., two or more units). In this embodiment, however, an example is given in which seven adjacent flat plate portions 2 are configured as one unit, and two units are configured.

[0029] That is, the plurality of flat plate portions 2 are configured so that the thicknesses of corresponding flat plate portions 2 belonging to each unit are the same in the direction in which the flat plate portions 2 are arranged (X axis). Specifically, the thicknesses of flat plate portions 2 provided at corresponding positions in each unit are the same. The flat plate portions 2 provided at corresponding positions in each unit are conceptually flat plate portions 2 that are in the same order within each unit when counted from one side of the radio wave scatterer 100 (for example, the -X direction in FIG. 4). That is, with regard to the thickness of each flat plate portion 2, the plurality of flat plate portions 2 are periodically arranged in each of the plurality of units.

[0030] In this embodiment, for example, the first flat plate portion 201 of the first unit and the first flat plate portion 208 of the second unit are configured to have the same thickness, and the second to seventh flat plate portions 202 to 207 of the first unit and the second to seventh flat plate portions 208 to 214 of the second unit are configured to have the same thickness.

[0031] (Method for determining the thickness of the flat part) Next, a description will be given of a method for determining the thickness of the plurality of flat plate portions 2 of the radio wave scatterer 100. That is, a description will be given of a method for determining the concave-convex pattern of the radio wave scatterer 100. Fig. 6 is a diagram showing an arithmetic expression for determining the thickness of the flat plate portion.

[0032] The thicknesses of the plurality of flat plate portions 2 are generally determined in accordance with the characteristics of the radio wave scatterer 100, based on the arithmetic formula (3) derived from the arithmetic formulas (1) and (2) in Fig. 6. Here, for example, each arithmetic formula will be explained, and then a method for determining the thicknesses of the plurality of flat plate portions 2 will be explained.

[0033] ===Characters=== First, the characters used in the following explanation will be explained. Fig. 7 is a diagram showing an example of characters used to explain radio wave scatterers. The characters shown in the "characters" column in Fig. 7 indicate the content shown in the "contents" column.

[0034] For example, "w" in FIG. 4 indicates the width of the flat plate portion 2.

[0035] Furthermore, "k" indicates a number that identifies the flat plate portion 2, and more specifically, indicates a number that corresponds to the order counted from one side (-X direction) to the other side (+X direction) of the radio wave scatterer 100, as shown in Fig. 4. In the example of Fig. 4, "k=1" indicating that "k" is "1" indicates the flat plate portion 201 in Fig. 3, and "k=2" indicates the flat plate portion 202.

[0036] "K" indicates the number of flat plate portions 2 contained in one unit, and the value of "K" is equal to or greater than 2. In the example of FIG. 4, seven flat plate portions 2 are contained in one unit, so the value of "K" is "7."

[0037] "N" indicates the number of units included in the radio wave scatterer 100. In the example of Fig. 4, two units are included in the radio wave scatterer 100, so the value of "N" is "2".

[0038] "θ" indicates the angle corresponding to the direction in which the plane waves from the flat plate portion 2 constructively interact with each other; specifically, it indicates the angle corresponding to the direction in which the plane waves corresponding to the radio waves reflected and scattered by the flat plate portion 2 constructively interact with each other, and indicates the angle in the XZ plane shown in Figure 4.

[0039] "D" indicates the distance between the reference plane 900 and the top surface of each flat plate portion 2 in the thickness direction (Z-axis direction in FIG. 4). The "reference plane" 900 is a plane used as a reference for determining the thickness of the flat plate portion 2, and is a plane set at a predetermined position in the thickness direction. The reference plane 900 is a plane parallel to the XY plane. The reference plane 900 can be set at any position, but for ease of explanation, in FIG. 4 it is illustrated at a position corresponding to the top surfaces of the flat plate portions 2 with "k=2" and "k=4". In the example of FIG. 4, "D" is illustrated as a representative in the portion indicating the distance between the reference plane 900 and the top surface of the flat plate portion 2 with "k=1".

[0040] "h" indicates the thickness of each flat plate portion 2. In the example of Fig. 4, "h" is representatively illustrated in the portion indicating the thickness of the flat plate portion 2 of "k=1".

[0041] "λ" in the arithmetic formula (1) in FIG. 6 indicates the wavelength of the radio wave irradiated (incident) on the radio wave scatterer 100.

[0042] "Ak" in the arithmetic formula (1) in FIG. 6 indicates the scattering amplitude value of each flat plate portion 2. The "scattering amplitude value" is a concept corresponding to the magnitude of the amplitude of radio waves reflected and scattered by the flat plate portion 2, and is a fixed value determined, for example, by the material of the flat plate portion 2. The "k" in "Ak" indicates the aforementioned "k." That is, "A1" corresponding to "k=1" indicates the scattering amplitude value of the flat plate portion 2 for "k=1," and "A2" corresponding to "k=2" indicates the scattering amplitude value of the flat plate portion 2 for "k=2." In this embodiment, a case will be described in which the multiple flat plate portions 2 are formed from the same metal material and the "Ak"s of the respective flat plate portions 2 are the same.

[0043] "δk" in the calculation formula (1) of FIG. 6 indicates a phase amount corresponding to the thickness of each flat plate portion 2. The "phase amount" is a quantity determined according to the aforementioned "D" (the distance between the reference plane 900 and the top surface of each flat plate portion 2), and is a concept indicating, for example, the optical distance corresponding to the "D". Note that the "k" in "δk" indicates the aforementioned "k", i.e., "δ1" corresponding to "k=1" indicates the phase amount of the flat plate portion 2 for "k=1", and "δ2" corresponding to "k=2" indicates the phase amount of the flat plate portion 2 for "k=2".

[0044] "α" in the arithmetic formula (2) in FIG. 6 indicates an angle corresponding to the direction in which the plane waves from the flat plate portion 2 side constructively interact with each other, and represents the same concept as "θ" described above.

[0045] "m" in the equation (2) in FIG. 6 indicates the diffraction order.

[0046] === Arithmetic expression === Next, each calculation formula will be explained. Note that here, as shown in Fig. 4 and Fig. 5, for example, a case where a plane wave corresponding to a radio wave is perpendicularly incident on the radio wave scatterer 100 from the +Z direction to the -Z direction will be explained.

[0047] =Arithmetic expression (1)= The arithmetic formula (1) in FIG. 6 is a formula that indicates the scattering pattern of the radio wave scatterer 100 that is determined based on the assumption that the plurality of flat plate portions 2 are radiating elements of an array antenna.

[0048] In addition, "Esum(θ)" in the calculation formula (1) indicates the scattering pattern of the radio waves reflected and scattered by the radio wave scatterer 100, and specifically indicates the electric field strength of the reflected waves superimposed on each other from each flat plate portion 2 in the direction of angle θ.

[0049] In addition, "g(θ)" in the calculation formula (1) is a concept corresponding to the radiation pattern of one element in array antenna theory, and in this embodiment, it is a concept indicating the scattering pattern in each flat plate portion 2, and has the same value in each flat plate portion 2.

[0050] Furthermore, the exp term in "D(θ)" in the calculation formula (1) indicates the optical distance or the difference in optical distance between each flat plate portion 2. For example, in the flat plate portions of "k=2" and "k=3" in FIG. 5, "(2π / λ)wsinθ" indicates the optical distance of the portion indicated by symbol 901 in FIG. 5, and "δk (specifically, δ3)" indicates the optical distance of the portion indicated by symbol 902 in FIG. 6.

[0051] In the radio wave scatterer 100, when a plane wave of radio waves is incident on each flat plate portion 2, a reflected wave is radiated from each flat plate portion 2. Since the thicknesses of the flat plate portions 2 are different from one another, the radio wave scatterer 100 can be considered as an array antenna in which radiating elements with a phase amount of δk are arranged, and the scattering pattern corresponding to the radiation pattern of the array antenna can be considered as the scattering pattern of the radio wave scatterer 100. Therefore, equation (1) can be used as an equation that indicates the scattering pattern of the radio wave scatterer 100.

[0052] =Arithmetic expression (2)= 6 is an arithmetic expression that indicates the condition under which plane waves corresponding to the radio waves that are reflected and scattered by the radio wave scatterer 100 constructively interfere with each other due to interference, and more specifically, it is an arithmetic expression that indicates the condition under which the plane waves corresponding to the radio waves that are reflected by the flat plate portion 2 that is each element constructively interfere with each other due to interference, for example, when the radio wave scatterer 100 is regarded as a reflective diffraction grating with a lattice constant Kw (in other words, when the radio wave scatterer 100 is regarded as a diffraction grating with a lattice constant Kw, the condition under which waves corresponding to the radio waves that are diffracted by the diffraction grating constructively interfere with each other due to interference).

[0053] =Arithmetic expression (3)= The arithmetic formula (3) in Figure 6 is a predetermined arithmetic formula that shows at least the relationship between "Esum(m)", which is the scattering pattern (i.e., electric field strength (electric field value)) of the radio waves scattered by the radio wave scatterer 100 at each diffraction order, and "δk", which is the phase amount corresponding to the thickness of the multiple flat plate portions 2.

[0054] Regarding this arithmetic expression (3), in arithmetic expression (2) indicating the constructive condition, "α" is converted to "θ" corresponding to arithmetic expression (1), and then "sinθ=mλ / Kw" from the converted arithmetic expression (2) is substituted into arithmetic expression (1), thereby converting arithmetic expression (1) into an arithmetic expression with "m" as a variable, thereby deriving arithmetic expression (3).

[0055] ===Decision Method=== Next, a method for determining the thickness of the flat plate portion 2 using the arithmetic expression (3) will be described. FIG. 8 is a diagram for explaining the method for determining the thickness of the flat plate portion. Here, for example, as shown in the "common conditions" in FIG. 8, when radio waves with a frequency of "28 GHz" are perpendicularly incident on the radio wave scatterer 100 as shown in FIG. 4, the width of the flat plate portion 2 is "10.71 mm", the period of one unit is "74.97 mm", and the overall width of the radio wave scatterer 100 is "149.94 mm". That is, the case will be described where one unit contains seven flat plate portions 2 (K=7) and the number of units in the radio wave scatterer 100 is two (N=2). Furthermore, although not shown in FIG. 8, the case will be described where "Ak", which is the scattering amplitude value of each flat plate portion 2, is a predetermined numerical value (for example, "1"). Note that "Ak" may be a value determined by any method, including experiments or simulations performed in advance.

[0056] We will explain how to determine the thickness of the flat plate portion 2 when, under the above-mentioned common conditions, the scattering pattern of the radio waves scattered by the radio wave scatterer 100 at each diffraction order corresponds to the following design guidelines 1 and 2.

[0057] =Design Policy 1= Design policy 1 is a policy for determining the thickness of the flat plate portion 2 so that the peaks of the scattering patterns of the diffraction orders m=0, m=±1, m=±2, and m=±3 are equal to each other.

[0058] In this case, the seven arithmetic equations Esum(0), Esum(±1), Esum(±2), and Esum(±3) derived by substituting m=0, m=±1, m=±2, and m=±3 into equation (3) in Figure 6 have the same value, so a total of seven equations are derived, for example, Esum(0)=1, Esum(±1)=1, Esum(±2)=1, and Esum(±3)=1. Note that although the right-hand sides of these equations are set to "1" here, other numerical values ​​may be used as long as they are the same.

[0059] Note that "k" in "δk" shown on the right side of the equation for D(m) in arithmetic formula (3) in Fig. 6 is substituted with "k=1" to "k=14", but since the thickness of the flat plate portion 2 of the radio wave scatterer 100 is configured periodically in unit units, δ1=δ8, δ2=δ, δ3=δ10, δ4=δ11, δ5=δ12, δ6=δ13, δ7=δ14. That is, in the above seven equations in total, seven variables (unknowns), δ1 to δ7, are provided, and it is possible to find δ1 to δ7 by solving these seven equations.

[0060] Here, for example, first, by substituting values ​​corresponding to design policy 1 into equation (3), a total of seven equations are derived: Esum(0) = 1, Esum(±1) = 1, Esum(±2) = 1, Esum(±3) = 1. These seven equations are then solved to find δ1 to δ7. Next, the wavelength of the radio waves is calculated based on "28 GHz" specified in the common conditions in Fig. 8, and the calculated wavelength of the radio waves is used to find the distance "D" (Fig. 4) between reference plane 900 and the top surface of each flat plate portion 2 corresponding to the previously found δ1 to δ7. The thickness of flat plate portion 2 ("h" in Fig. 4) is then determined so as to achieve this found "D."

[0061] The specific method for determining the distance "D" (Figure 4) between the reference plane 900 corresponding to δ1 to δ7 and the top surface of each flat portion 2 may be any method, but for example, the solution to (2D / λ)×2π=δk may be used as the value of "D".

[0062] When solving seven equations to find δ1 to δ7, it is possible that there will be no solution to the equations. In this case, any method such as the least squares method may be used to find values ​​close to the solutions, and these found values ​​may be used as δ1 to δ7.

[0063] =Design Policy 2= Design policy 2 is to determine the thickness of the flat plate portion 2 so that the peak of the scattering pattern for diffraction order m=0 is "0" and the peaks of the scattering patterns for m=±1, m=±2, and m=±3 are equal to each other.

[0064] Here, for example, first, by substituting values ​​corresponding to design principle 2 into equation (3), a total of seven equations are derived: Esum(0) = 0, Esum(±1) = 1, Esum(±2) = 1, Esum(±3) = 1. These seven equations are then solved to find δ1 to δ7. Thereafter, the thickness of each flat plate portion 2 is determined in the same manner as in design principle 1.

[0065] (verification) Next, the verification results of the radio wave scatterer 100 having the plate portion 2 (i.e., uneven pattern) with a thickness determined by applying the above-mentioned "method for determining the thickness of the plate portion" will be described. Figs. 9 to 11 are diagrams relating to radio waves scattered by the radio wave scatterer. (a) of each diagram shows the scattering characteristics (i.e., scattering pattern, scattering intensity) of radio waves by the radio wave scatterer 100 having the plate portion 2 with a thickness corresponding to design guideline 1 (i.e., the thickness determined in design guideline 1). (b) of each diagram shows the scattering characteristics (i.e., scattering pattern, scattering intensity) of radio waves by the radio wave scatterer 100 having the plate portion 2 with a thickness corresponding to design guideline 2 (i.e., the thickness determined in design guideline 2).

[0066] 9 show scattering characteristics (i.e., scattering intensity) of radio waves by the radio wave scatterer 100, calculated taking into account the thickness of the flat-plate portion 2, for the radio wave scatterer 100 including the flat-plate portion 2 having a thickness determined by applying the above-mentioned "(Method for Determining the Thickness of the Flat-plate portion)." That is, FIG. 9 shows scattering characteristics corresponding to theoretical values ​​calculated taking into account the thickness of the flat-plate portion 2. Any theoretical formula can be used to calculate these theoretical values, and for example, a formula corresponding to calculation formula (1) in FIG. 6 may be used. FIG. 10 shows scattering characteristics corresponding to the analysis results of electromagnetic wave analysis using the finite difference time domain method (FDTD) for the radio wave scatterer 100 including the flat-plate portion 2 having a thickness determined by applying the above-mentioned "(Method for Determining the Thickness of the Flat-plate portion)." FIG. 11 shows scattering characteristics corresponding to the measurement results (measured values) of actual measurements for the radio wave scatterer 100 including the flat-plate portion 2 having a thickness determined by applying the above-mentioned "(Method for Determining the Thickness of the Flat-plate portion)."

[0067] 9 to 11(a), almost the same peaks are shown when the diffraction order is m=0, m=±1, m=±2, and m=±3, so it was confirmed that by applying the thickness of the flat plate portion 2 determined using the above-mentioned method, a radio wave scatterer 100 corresponding to design principle 1 was designed. Furthermore, in the graphs of Fig. 9 to 11(a), similar trends were confirmed for m=0, m=±1, m=±2, and m=±3, so it was confirmed by a plurality of types of verification methods that by applying the thickness of the flat plate portion 2 determined using the above-mentioned method, a radio wave scatterer 100 corresponding to design principle 1 was designed.

[0068] 9 to 11(b), when the diffraction order is m=±1, m=±2, and m=±3, almost the same peak is shown, when the diffraction order is m=0, an extremely low peak is shown, and when the diffraction order is m=±1, m=±2, and m=±3, almost the same peak is shown, so it was confirmed that by applying the thickness of the flat plate portion 2 determined using the above-mentioned method, a radio wave scatterer 100 corresponding to design principle 2 was designed. Furthermore, in the graphs of FIGS. 9 to 11(b), similar trends were confirmed for m=0, m=±1, m=±2, and m=±3, so it was confirmed by a plurality of types of verification methods that by applying the thickness of the flat plate portion 2 determined using the above-mentioned method, a radio wave scatterer 100 corresponding to design principle 2 was designed.

[0069] (Effects of this embodiment) According to this embodiment, by providing a plurality of flat plate portions 2 that scatter radio waves, it is possible to scatter radio waves, for example, and thereby reduce radio wave blind zones. Furthermore, by determining the thicknesses of the plurality of flat plate portions 2 based on a predetermined arithmetic expression, for example, the thicknesses of the plurality of flat plate portions 2 can be easily determined, and therefore the radio wave scatterer 100 can be easily designed.

[0070] [III] Modifications to the embodiment Although the embodiments of the present invention have been described above, the specific configurations and means of the present invention can be arbitrarily modified and improved within the scope of the technical ideas of each invention described in the claims.

[0071] (Regarding the flat part) In the above embodiment, the radio wave scatterer 100 is formed by arranging the flat plate portion 2 on the base portion 1 as shown in Fig. 2 and Fig. 3, but the present invention is not limited to this. For example, the portion corresponding to the base portion 1 and the portion corresponding to the flat plate portion 2 may be integrally formed. That is, the radio wave scatterer 100 may be formed by cutting a metal plate having a predetermined thickness so as to become the radio wave scatterer 100 having the concave-convex pattern shown in Fig. 2 and Fig. 3, or the radio wave scatterer 100 may be formed using a predetermined mold.

[0072] (Regarding the incident direction of a plane wave) Furthermore, in the above embodiment, a case has been described in which a plane wave corresponding to a radio wave is perpendicularly incident on the radio wave scatterer 100, but the present invention is not limited to this, and a plane wave may be incident from an oblique direction. In this case, the first term in the exponent on the upper side indicating "D(θ)" in the arithmetic formula (1) in Fig. 6 may be changed to an equation corresponding to the case in which a plane wave is incident from an oblique direction.

[0073] (About the number) Furthermore, in the above embodiment, an example has been described in which the number of flat plate portions 2 included in one unit is seven, and the number of units included in the radio wave scatterer 100 is two, but the number is not limited to these, and the radio wave scatterer 100 may be designed and installed with other numbers. [Explanation of symbols]

[0074] 1 base 2 Flat plate part 100 Radio wave scatterer 201 Flat plate part 202 Flat plate part 203 Flat plate part 204 Flat plate part 205 Flat plate part 206 Flat plate part 207 Flat plate part 208 Flat plate part 209 Flat plate part 210 Flat plate part 211 Flat plate part 212 Flat plate part 213 Flat plate part 214 Flat Panel 900 datum level 901 Symbol 902 Symbol

Claims

1. A radio wave scatterer that scatters radio waves, The antenna includes a plurality of plate-like portions arranged adjacent to each other, the plate-like portions scattering radio waves, The widths of the plurality of plate-like portions are the same. the thicknesses of the plurality of plate-like portions are determined based on a predetermined calculation formula; the predetermined calculation formula is determined based on a scattering pattern of the radio wave scatterer, which is determined based on the assumption that the plurality of plate-like portions are radiating elements of an array antenna, and on a condition under which radio waves reflected by the plurality of plate-like portions constructively interfere with each other, the predetermined arithmetic expression indicates at least a relationship between an electric field value of the radio wave scattered by the radio wave scatterer at each diffraction order and a phase amount corresponding to a thickness of the plurality of plate-like portions, The plurality of plate-like portions are provided in a number of units, with K (K is an integer of 2 or more) plate-like portions that are consecutively adjacent to each other as one unit, the plurality of plate-like portions are periodically arranged in each of the plurality of units, The predetermined calculation formula is the following formula: [Equation 1] In the above formula, Esum(m) represents the electric field value of the radio wave scattered by the radio wave scatterer at each diffraction order, m denotes the diffraction order, K represents the number of plate-like portions in one unit, N indicates the number of the multiple units, A represents the scattering amplitude value in the plurality of plate-like portions, δ represents a phase amount corresponding to the thickness of the plurality of plate-like portions, The thicknesses of the plurality of plate-like portions are determined based on the δk calculated based on the predetermined arithmetic formula by setting the Esum (m) necessary to eliminate the dead zone of the radio wave, and the determined thicknesses are determined based on the δk and the frequency of the radio wave. Radio wave scatterer.

2. The thicknesses of the plurality of plate-like portions are determined based on the calculated δk and the frequency of the radio wave by setting all of the Esum (m) to be equal to each other, and then determining the δk calculated based on the predetermined arithmetic formula. The radio wave scatterer according to claim 1 .

3. The thickness of the plurality of plate-like portions is determined based on the δk calculated based on the predetermined arithmetic formula by setting Esum(m) to 0 when the diffraction order m is 0, and setting all Esum(m) to be equal to each other when m is other than 0, and then determining the thickness of the plurality of plate-like portions based on the calculated δk and the frequency of the radio wave. The radio wave scatterer according to claim 1 .

4. The plurality of plate-shaped portions are made of metal. The radio wave scatterer according to any one of claims 1 to 3.

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