Electromagnetic wave control plate

Abstract

This electromagnetic wave control plate can emit incident electromagnetic waves in a prescribed direction, and includes a plurality of unit structures arranged on a first surface. The unit structure includes: a first substrate; a first electrode provided to the first substrate and formed in a mesh shape in plan view; a second substrate provided facing the first substrate; a second electrode provided to the second substrate, facing the first electrode, and formed in a mesh shape in plan view; and a liquid crystal layer provided between the first substrate and the second substrate. At least one of the first electrode and the second electrode is formed so that at least a part of a region where the first electrode and the second electrode overlap each other in plan view has a higher mesh density than at least a part of a region where the first electrode and the second electrode do not overlap in plan view.

Description

Radio Control Board

[0001] The present disclosure relates to a radio wave control board.

[0002] There are known techniques for controlling radio waves without using a dielectric lens. For example, Patent Document 1 describes a technique for refracting radio waves by changing the parameters of each element in a structure in which resonator elements are arranged. Furthermore, techniques for controlling radio waves have been studied from various perspectives (for example, Non-Patent Document 1).

[0003] JP 2015-231182 A

[0004] Hong, I.-P. Reviews Based on the Reconfigurable Intelligent Surface Technical Issues. Electronics 2023, 12, 4489. https: / / doi.org / 10.3390 / electronics12214489

[0005] The radio wave control board of the present disclosure is a radio wave control board capable of emitting incident radio waves in a predetermined direction, and includes a plurality of unit structures arranged on a first surface, the unit structures including a first substrate, a first electrode provided on the first substrate and formed in a mesh shape in a planar view, a second substrate provided opposite the first substrate, a second electrode provided on the second substrate and facing the first electrode and formed in a mesh shape in a planar view, and a liquid crystal layer provided between the first substrate and the second substrate, and at least one of the first electrode and the second electrode is formed so that at least a portion of the area where the first electrode and the second electrode overlap in a planar view has a higher mesh density than at least a portion of the area where the first electrode and the second electrode do not overlap in a planar view.

[0006] The radio wave control board of the present disclosure is a radio wave control board capable of emitting incident radio waves in a predetermined direction, and includes a plurality of unit structures arranged on a first surface, the unit structures including a first substrate, a first electrode provided on the first substrate and formed in a mesh shape in a planar view, a second substrate provided opposite the first substrate, a second electrode provided on the second substrate and facing the first electrode and formed in a mesh shape in a planar view, and a liquid crystal layer provided between the first substrate and the second substrate, and at least one of the first electrode and the second electrode has a higher effective conductivity in at least a portion of the area where the first electrode and the second electrode overlap in a planar view than in an area where the first electrode and the second electrode do not overlap in a planar view.

[0007] The radio wave control board of the present disclosure is a radio wave control board capable of emitting incident radio waves in a predetermined direction, and includes a plurality of unit structures arranged on a first surface, the unit structures including a first substrate, a first electrode provided on the first substrate and formed in a mesh shape in a planar view, a second substrate provided opposite the first substrate, a second electrode provided on the second substrate and facing the first electrode and formed in a mesh shape in a planar view, and a liquid crystal layer provided between the first substrate and the second substrate, and at least one of the first electrode and the second electrode has at least a portion of the area where the first electrode and the second electrode overlap in a planar view covered with a transparent conductive material.

[0008] FIG. 1 is a diagram for explaining an overview of a radio wave control plate according to an embodiment. FIG. 2 is a cross-sectional view showing an example of the configuration of a unit structure according to the first embodiment. FIG. 3 is a diagram showing an example of the configuration of an electrode according to the first embodiment. FIG. 4 is a diagram for explaining a method for designing a mesh according to the first embodiment. FIG. 5 is a diagram for explaining the shape of a mesh according to a first example of the first embodiment. FIG. 6 is a diagram for explaining the shape of a mesh according to a second example of the first embodiment. FIG. 7 is a diagram for explaining the shape of a mesh according to a third example of the first embodiment. FIG. 8 is a diagram showing an example of the configuration of an electrode according to a modified example of the first embodiment. FIG. 9 is a diagram for explaining an overview of a second embodiment. FIG. 10 is a cross-sectional view showing an example of the configuration of a unit structure according to the second embodiment.

[0009] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to this embodiment, and in the following embodiments, the same components are designated by the same reference numerals, and redundant explanations will be omitted.

[0010] [Overview] (Radio wave control board) An overview of the radio wave control board will be described with reference to Fig. 1. Fig. 1 is a diagram for explaining the overview of the radio wave control board according to the embodiment.

[0011] The radio wave control plate 1 is configured to be able to control the direction of travel of incident radio waves. For example, when receiving radio waves transmitted from a base station, the radio wave control plate 1 is configured to reflect or refract (transmit) the radio waves at a predetermined angle. The radio wave control plate 1 may be made of, for example, a metamaterial that changes the phase of the incident wave. The radio wave control plate 1 may be capable of controlling not only one of the reflection direction and the refraction direction of the radio waves, but also both. In the present disclosure, reflection and refraction are sometimes collectively referred to as emission.

[0012] 1, the radio wave control plate 1 may include, for example, a substrate 2 and unit structures 10a, 10b, 10c, and 10d. When there is no need to distinguish between the unit structures 10a to 10d, they will be collectively referred to as unit structures 10. The unit structures 10 are also called metasurface elements.

[0013] The unit structures 10a, 10b, 10c, and 10d may be formed on a substrate 2. The substrate 2 may be, for example, a dielectric substrate made of a dielectric material. The substrate 2 may have, for example, but is not limited to, a rectangular shape. The unit structures 10a, 10b, 10c, and 10d may be arranged two-dimensionally.

[0014] In the radio wave control board 1, a plurality of unit structures 10a are arranged along the X-axis direction on one tier. A plurality of unit structures 10b are arranged along the X-axis direction on the tier above the tier on which unit structures 10a are arranged. A plurality of unit structures 10c are arranged along the X-axis direction on the tier above the tier on which unit structures 10b are arranged. A plurality of unit structures 10d are arranged along the X-axis direction on the tier above the tier on which unit structures 10c are installed. In the example shown in FIG. 1 , unit structures 10a, 10b, 10c, and 10d are periodically arranged along the Y-axis direction. Note that the unit structures do not need to be arranged parallel to the X-axis and Y-axis directions. For example, the arrangement direction of the plurality of unit structures 10a does not need to intersect perpendicularly with the arrangement direction of unit structures 10a, 10b, 10c, and 10d.

[0015] By varying the properties of each of unit structures 10a to 10d (for example, the relative dielectric constant of the liquid crystal layer, described later), it is possible to vary the phase change amount (the difference between the phase of the incident radio wave and the phase of the outgoing radio wave) of each of unit structures 10a to 10d. By varying the properties of each of unit structures 10a to 10d so that the phase change amount increases (or decreases) sequentially, radio wave control board 1 has a gradient of phase change amount. Due to the gradient of phase change amount, radio wave control board 1 can reflect and / or refract incident radio waves in a predetermined direction. Note that, although unit structures 10a to 10d are rectangular in shape in FIG. 1, the shape of the unit structures is not limited to rectangular.

[0016] [First embodiment] (Unit structure) A configuration example of a unit structure according to the first embodiment will be described with reference to Fig. 2 and Fig. 3. Fig. 2 is a cross-sectional view showing a configuration example of a unit structure according to the first embodiment. Fig. 3 is a diagram showing a configuration example of an electrode according to the first embodiment.

[0017] As shown in FIG. 2, the unit structure 10 includes a first substrate 2-1, a second substrate 2-2, a first electrode 12, a second electrode 14, and a liquid crystal layer 16.

[0018] The first substrate 2-1 is preferably formed of a dielectric material, particularly a dielectric material that is substantially transparent to visible light, such as glass or a PET film, because this makes the appearance of the substrate 2 less conspicuous.

[0019] The second substrate 2-2 is provided at a position spaced apart from the first substrate 2-1 in the -Z direction. The second substrate 2-2 faces the first substrate 2-1. The second substrate 2-2 is preferably formed of a dielectric material. In particular, it is preferably formed of a dielectric material that is substantially transparent to visible light, such as glass or a PET film. This is because the appearance of the substrate 2 becomes less noticeable.

[0020] The first electrode 12 is provided on the first substrate 2-1. The first electrode 12 extends in the XY plane. The first electrode 12 is formed of, for example, a metal. The first electrode 12 is formed of, for example, copper, but is not limited to this. The first electrode 12 is formed in a mesh shape. Because the first electrode 12 is formed in a mesh shape, gaps (mesh holes) exist between the multiple metal wires that make up the first electrode 12 (between two adjacent metal wires). Note that the metal wires may contain elements other than metal elements.

[0021] The second electrode 14 is provided on the second substrate 2-2. The second electrode 14 faces the first electrode 12. The second electrode 14 is formed of, for example, a metal. The second electrode 14 is formed of, for example, copper, but is not limited to this. The second electrode 14 is formed in a mesh shape. Since the second electrode 14 is formed in a mesh shape, mesh holes are formed between the multiple metal wires that make up the second electrode 14 (between two adjacent metal wires). The metal wires may contain elements other than metal elements.

[0022] FIG. 3 is a top view of the unit feature 10. FIG. 3 is a diagram illustrating an example configuration of the first electrode 12 and the second electrode 14. The unit feature 10 includes first electrodes 12-1, 12-2, 12-3, and 12-4 as the first electrodes 12. The first electrodes 12-1 to 12-4 are formed, for example, in a rectangular shape. The second electrode 14 includes an opening 18. The opening 18 includes a rectangular opening formed in the center of the unit feature 10 and rectangular openings extending from the rectangular opening toward each vertex of the unit feature 10. The first electrodes 12-1 to 12-4 and the second electrode 14 are arranged so that they at least partially overlap when viewed in a direction perpendicular to the XY plane (in a planar view). When it is not necessary to distinguish between the first electrodes 12-1 to 12-4, they are collectively referred to as the first electrodes 12.

[0023] Regions 21 and 22 are regions where the first electrode 12-1 and the second electrode 14 overlap when viewed from the direction perpendicular to the XY plane. Regions 23 and 24 are regions where the first electrode 12-2 and the second electrode 14 overlap when viewed from the direction perpendicular to the XY plane. Regions 25 and 26 are regions where the first electrode 12-3 and the second electrode 14 overlap when viewed from the direction perpendicular to the XY plane. Regions 27 and 28 are regions where the first electrode 12-4 and the second electrode 14 overlap when viewed from the direction perpendicular to the XY plane.

[0024] The liquid crystal layer 16 is provided between the first electrode 12 and the second electrode 14. The first electrode 12 and the second electrode 14 apply a voltage to the liquid crystal layer 16. By applying a voltage to the liquid crystal layer 16, the orientation of the liquid crystal molecules contained in the liquid crystal layer 16 can be controlled (dynamically changed). This makes it possible to dynamically change the relative dielectric constant of the liquid crystal layer 16 of each unit feature 10. Therefore, it is possible to dynamically change the gradient of the phase change amount of the radio wave control plate 1. This makes it possible to dynamically change the reflection direction and / or transmission direction of the radio wave by the radio wave control plate 1.

[0025] [Method of Designing a Mesh] A method of designing a mesh according to the first embodiment will be described with reference to Fig. 4. Fig. 4 is a diagram for explaining the method of designing a mesh according to the first embodiment.

[0026] FIG. 4 shows an enlarged view of the first electrode 12-1 and the second electrode 14. As shown in FIG. 4, the first electrode 12-1 and the second electrode 14 have regions 21 and 22 where the first electrode 12-1 and the second electrode 14 overlap when viewed perpendicularly to the XY plane (in a plan view), and a region 30 where the first electrode 12-1 and the second electrode 14 do not overlap when viewed in a plan view (region 30 consists of a non-overlapping region in the first electrode 12-1 and a non-overlapping region in the second electrode 14). In the example shown in FIG. 4, the first electrode 12-1 and the second electrode 14 are formed so that the effective conductivity in regions 21 and 22 is higher than the effective conductivity in the non-overlapping region 30. For example, at least one of the first electrode 12-1 and the second electrode 14 is formed so that the mesh density in regions 21 and 22 is higher than the mesh density in the non-overlapping region 30.

[0027] Here, the first electrode 12-1 and / or the second electrode 14 do not need to be formed so that the effective conductivity in the entire region 21 and the region 22 is higher than the effective conductivity in the non-overlapping region 30. It is sufficient that the effective conductivity in at least a part of the region 21 and the region 22 (a part of the region 21 and / or a part of the region 22) is higher than the effective conductivity in the non-overlapping region 30.

[0028] Furthermore, the first electrode 12-1 and / or the second electrode 14 may have an effective conductivity in a portion of the non-overlapping region 30 that is equal to or greater than the highest effective conductivity in the regions 21 and 22. For example, with respect to the first electrode 12-1, the mesh density of the outer periphery (side) of the first electrode 12-1 may be the same as the mesh density in the regions 21 and 22, even in the non-overlapping region 30. Furthermore, for example, the mesh density of the non-overlapping region of either the first electrode 12-1 or the second electrode 14 within the non-overlapping region 30 may be the same as the mesh density in the regions 21 and 22. In other words, it is sufficient that at least one of the first electrode 12-1 and the second electrode 14 is formed so that the effective conductivity in at least a portion of the regions 21 and 22 is higher than the effective conductivity in at least a portion of the non-overlapping region 30. The relationship between the first electrodes 12-2 to 12-4 and the second electrode 14 is the same as the relationship between the first electrode 12-1 and the second electrode 14, and therefore a description thereof will be omitted.

[0029] By increasing the mesh density in at least a portion of region 21 and region 22, the electric flux density applied to the liquid crystal layer 16 in those regions can be made higher than in the absence of such density. This makes it easier to control the orientation of the liquid crystal molecules contained in the liquid crystal layer 16. Increasing the mesh density in a portion of the electrode, as in this embodiment, can reduce the electrode's irregularities compared to a non-increased region. Reducing the electrode's irregularities can also make it easier to control the orientation of the liquid crystal molecules. Furthermore, because a strong electric field is distributed in the region where the first electrode 12 and the second electrode 14 overlap, it becomes easier to control the liquid crystal molecules in the liquid crystal layer 16 corresponding to at least a portion of this region, which leads to the radio wave control board 1 being able to dynamically change the refraction and / or reflection direction of radio waves. Furthermore, the appearance is less noticeable than when the mesh density is increased in all regions of the electrode.

[0030] [Mesh Shape] (First Example) The shape of the mesh holes according to the first example of the first embodiment will be described with reference to Fig. 5. Fig. 5 is a diagram for explaining the shape of the mesh holes according to the first example of the first embodiment.

[0031] FIG. 5 schematically illustrates an enlarged view of the first electrode 12-1 (or the second electrode 14). As shown in FIG. 5, the first electrode 12-1 is formed of metal wires 41 and has mesh holes 42. As shown in FIG. 5, the size of the mesh holes 42 in the region 21 (or region 22) is larger than the size of the mesh holes 42 in the region 30. That is, the first electrode 12-1 (or the second electrode 14) is formed such that the mesh density in the region 21 (or region 22) is higher than the mesh density in the region 30. In this case, it is sufficient that at least one of the first electrode 12-1 and the second electrode 14 is formed such that the mesh density in at least a portion of the region 21 (or region 22) is higher than the mesh density in the region 30. Although the mesh density has been described as being changed by changing the size of the mesh holes 42 between the region 21 and the region 22 and the region 30, the present disclosure is not limited thereto. For example, the mesh density may be changed by changing the width of the metal wire 41 between the region 21 and the region 22 and the region 30. Increasing the mesh density of the region 21 (or the region 22) also includes configuring the region 21 (or the region 22) without mesh holes (for example, configuring the region as a single plate).

[0032] In the example shown in FIG. 5, the mesh holes 42 have an effective conductivity σ of the first electrode 12-1 (or the second electrode 14). ｅｆｆ is expressed by the following formula (1), where σ is the conductivity of the material of the first electrode 12-1 (or the second electrode 14), w is the line width of the metal wire 41, g is the width of the mesh hole 42, and ψ = w / (w + g). ψ is called the fill factor. If the first electrode 12-1 (or the second electrode 14) is formed of a metal plate without mesh holes, ψ = 1.

[0033] σ ｅｆｆ = σ × (2ψ − ψ ２ ) ... (1)

[0034] As shown in formula (1), by changing the line width of the metal wire 41 and the width of the mesh hole 42, the effective conductivity σ ｅｆｆ The effective conductivity σ can be changed. ｅｆｆFrom this viewpoint, it is preferable that ψ=1, that is, the first electrode 12-1 (or the second electrode 14) is formed of a metal plate without a mesh.

[0035] (Second Example) The shape of a mesh hole according to a second example of the first embodiment will be described with reference to Fig. 6. Fig. 6 is a diagram for explaining the shape of a mesh hole according to the second example of the first embodiment.

[0036] 6 , in the second example, the size of the mesh holes 42 in the region 21 (or region 22) is formed so as to gradually decrease from the boundary between the region 21 (or region 22) and the region 30. That is, the mesh density in the region 21 (or region 22) is formed so as to gradually decrease from the boundary between the region 24 (or region 22) and the region 30. That is, the sizes of the mesh holes 42 included in the region 21 (or region 22) may be different.

[0037] (Third Example) The shape of a mesh according to a third example of the first embodiment will be described with reference to Fig. 7. Fig. 7 is a diagram for explaining the shape of a mesh according to the third example of the first embodiment.

[0038] 7, in the third example, the region 21 (or the region 22) includes a triangular mesh hole 42 and a square mesh hole 42. That is, the region 21 (or the region 22) may include mesh holes 42 of different shapes.

[0039] As described above, in the first embodiment, at least one of the first electrode and the second electrode has a mesh density higher in at least a portion of the area where the first electrode and the second electrode overlap in a plan view than in at least a portion of the area where the first electrode and the second electrode do not overlap in a plan view, which makes it easier to control the orientation of the liquid crystal molecules contained in the liquid crystal layer 16.

[0040] [Modification of First Embodiment] A configuration example of an electrode according to a modification of the first embodiment will be described with reference to Fig. 8. Fig. 8 is a diagram showing a configuration example of an electrode according to a modification of the first embodiment.

[0041] The unit structure 10A includes a first electrode 12A and a second electrode 14A. It differs from the unit structure 10 shown in FIG. 3 in that it includes a single first electrode 12A and a rectangular opening 18A. In the example shown in FIG. 8 , the first electrode 12A and the second electrode 14A also have, when viewed perpendicular to the XY plane (in a plan view), a region 21A and a region 22A where the first electrode 12-1 and the second electrode 14 overlap, and a region 30A where the first electrode 12-1 and the second electrode 14 do not overlap in a plan view. For at least one of the first electrode 12A and the second electrode 14A, the mesh density of at least a portion of the region 21A and the region 22A is formed to be higher than the mesh density of at least a portion of the other region, thereby making it easier to control the orientation of the liquid crystal molecules contained in the liquid crystal layer 16.

[0042] Second Embodiment An outline of a second embodiment will be described with reference to Fig. 9. Fig. 9 is a diagram for explaining an outline of the second embodiment.

[0043] As described above, in the present disclosure, the first electrode 12 and the second electrode 14 are formed in a mesh shape and therefore have metal wires 41 and mesh holes 42. In the present disclosure, a transparent conductive material 50 is provided so as to cover the metal wires 41 and the mesh holes 42.

[0044] (Unit Structure) A configuration example of a unit structure according to the second embodiment will be described with reference to Fig. 10. Fig. 10 is a cross-sectional view showing a configuration example of a unit structure according to the second embodiment.

[0045] 10, the unit structure 10A includes a first substrate 2-1, a second substrate 2-2, a first electrode 12, a second electrode 14, a liquid crystal layer 16, and transparent conductive materials 50-1 and 50-2. The unit structure 10A differs from the unit structure 10 shown in FIG. 2 in that the unit structure 10A includes the transparent conductive materials 50-1 and 50-2.

[0046] The transparent conductive material 50-1 is provided so as to cover the first electrode 12. The transparent conductive material 50-2 is provided so as to cover the second electrode 14. The transparent conductive material 50-1 and the transparent conductive material 50-2 are substantially transparent to visible light and are conductive. The transparent conductive material 50-1 and the transparent conductive material 50-2 are formed of, for example, ITO (Indium Tin Oxide). When there is no need to distinguish between the transparent conductive material 50-1 and the transparent conductive material 50-2, they may be collectively referred to as the transparent conductive material 50.

[0047] By covering the first electrode 12 and the second electrode 14 with the transparent conductive material 50-1 and the transparent conductive material 50-2, respectively, it is possible to increase the electric flux density that can be applied to the liquid crystal layer 16 compared to when not covered. This makes it easier to control the orientation of the liquid crystal molecules contained in the liquid crystal layer 16.

[0048] In the second embodiment, the first electrode 12 and the second electrode 14 do not have to be entirely covered with the transparent conductive material 50-1 and the transparent conductive material 50-2, respectively. For example, in at least one of the first electrode 12 and the second electrode 14, at least a portion of the region where the first electrode 12 and the second electrode 14 overlap in a planar view may be covered with the transparent conductive material 50. This allows a higher electric flux density to be applied to the liquid crystal layer 16 compared to when the transparent conductive material 50 is not provided. This makes it easier to control the orientation of the liquid crystal molecules contained in the liquid crystal layer 16. Furthermore, by covering the electrodes with the transparent conductive material as in this embodiment, unevenness caused by the electrodes may be reduced compared to when not covered. This reduction in unevenness may also make it easier to control the orientation of the liquid crystal molecules.

[0049] Furthermore, the first embodiment and the second embodiment may be combined. For example, in at least one of the first electrode 12 and the second electrode 14, a mesh density may be formed higher in at least a part of the region where the first electrode 12 and the second electrode 14 overlap in a plan view than in the region where they do not overlap, and the first electrode 12 and the second electrode 14 may further be covered with a transparent conductive material 50.

[0050] The present disclosure may also take the following configuration: (1) A radio wave control board capable of emitting incident radio waves in a predetermined direction, the radio wave control board including a plurality of unit structures arranged on a first surface, the unit structures including: a first substrate, a first electrode provided on the first substrate and formed in a mesh shape in a plan view, a second substrate provided opposite the first substrate, a second electrode provided on the second substrate and facing the first electrode, the second electrode being formed in a mesh shape in a plan view, and a liquid crystal layer provided between the first substrate and the second substrate, wherein at least one of the first electrode and the second electrode is formed so that at least a portion of an area where the first electrode and the second electrode overlap in a plan view has a higher mesh density than at least a portion of an area where the first electrode and the second electrode do not overlap in a plan view. (2) The radio wave control board according to (1), wherein at least one of the first electrode and the second electrode has a mesh line width that is thicker in at least a portion of an area where the first electrode and the second electrode overlap in a planar view than in at least a portion of an area where the first electrode and the second electrode do not overlap in a planar view. (3) The radio wave control board according to (1) or (2), wherein at least a portion of an area where the first electrode and the second electrode overlap in a planar view is formed of a material that is different from at least a portion of an area where the first electrode and the second electrode do not overlap in a planar view. (4) The radio wave control board according to any one of (1) to (3), wherein at least a portion of the area where the first electrode and the second electrode overlap in a planar view is covered with a transparent conductive material.(5) A radio wave control board capable of emitting incident radio waves in a predetermined direction, comprising a plurality of unit structures arranged on a first surface, wherein the unit structures comprise: a first substrate; a first electrode provided on the first substrate and formed in a mesh shape in a planar view; a second substrate provided opposite the first substrate; a second electrode provided on the second substrate and facing the first electrode and formed in a mesh shape in a planar view; and a liquid crystal layer provided between the first substrate and the second substrate, wherein at least one of the first electrode and the second electrode has a higher effective conductivity in at least a part of an area where the first electrode and the second electrode overlap in a planar view than an area where the first electrode and the second electrode do not overlap in a planar view. (6) The radio wave control board according to (5), wherein at least one of the first electrode and the second electrode has at least a part of an area where the first electrode and the second electrode overlap in a planar view formed of a material different from an area where the first electrode and the second electrode do not overlap in a planar view. (7) The radio wave control board according to (5) or (6), wherein at least a part of an area where the first electrode and the second electrode overlap in a planar view is covered with a transparent conductive material. (8) A radio wave control board capable of emitting incident radio waves in a predetermined direction, comprising a plurality of unit structures arranged on a first surface, wherein the unit structures comprise: a first substrate; a first electrode provided on the first substrate and formed in a mesh shape in a planar view; a second substrate provided opposite the first substrate; a second electrode provided on the second substrate and facing the first electrode and formed in a mesh shape in a planar view; and a liquid crystal layer provided between the first substrate and the second substrate, wherein at least one of the first electrode and the second electrode has at least a portion of an area where the first electrode and the second electrode overlap in a planar view covered with a transparent conductive material.

[0051] REFERENCE SIGNS LIST 1 Radio wave control plate 2 Substrate 2-1 First substrate 2-2 Second substrate 10, 10A Unit structure 12, 12-1 First electrode 14 Second electrode 16 Liquid crystal layer 41 Metal wire 42 Mesh hole 50, 50-1, 50-2 Transparent conductive material

Claims

1. A radio wave control board capable of emitting incident radio waves in a predetermined direction, comprising a plurality of unit structures arranged on a first surface, wherein the unit structures comprise: a first substrate; a first electrode provided on the first substrate and formed in a mesh shape in a planar view; a second substrate provided opposite the first substrate; a second electrode provided on the second substrate and facing the first electrode and formed in a mesh shape in a planar view; and a liquid crystal layer provided between the first substrate and the second substrate, wherein at least one of the first electrode and the second electrode is formed so that at least a portion of the area where the first electrode and the second electrode overlap in a planar view has a higher mesh density than at least a portion of the area where the first electrode and the second electrode do not overlap in a planar view.

2. A radio wave control board as described in claim 1, wherein at least one of the first electrode and the second electrode has a mesh line width that is thicker in at least a portion of the area where the first electrode and the second electrode overlap in a planar view than in at least a portion of the area where the first electrode and the second electrode do not overlap in a planar view.

3. A radio wave control board as described in claim 1 or 2, wherein at least one of the first electrode and the second electrode is formed of a material in which at least a portion of the area where the first electrode and the second electrode overlap in a planar view is made of a different material from at least a portion of the area where the first electrode and the second electrode do not overlap in a planar view.

4. A radio wave control board as described in any one of claims 1 to 3, wherein at least one of the first electrode and the second electrode has at least a portion of the area where the first electrode and the second electrode overlap in a planar view covered with a transparent conductive material.

5. A radio wave control board capable of emitting incident radio waves in a predetermined direction, comprising a plurality of unit structures arranged on a first surface, wherein the unit structures comprise: a first substrate; a first electrode provided on the first substrate and formed in a mesh shape in a planar view; a second substrate provided opposite the first substrate; a second electrode provided on the second substrate and facing the first electrode and formed in a mesh shape in a planar view; and a liquid crystal layer provided between the first substrate and the second substrate, wherein at least one of the first electrode and the second electrode has a higher effective conductivity in at least a portion of an area where the first electrode and the second electrode overlap in a planar view compared to an area where the first electrode and the second electrode do not overlap in a planar view.

6. A radio wave control board as described in claim 5, wherein at least one of the first electrode and the second electrode has at least a portion of an area where the first electrode and the second electrode overlap in a planar view formed of a material different from that of an area where the first electrode and the second electrode do not overlap in a planar view.

7. A radio wave control board as described in claim 5 or 6, wherein at least one of the first electrode and the second electrode has at least a portion of the area where the first electrode and the second electrode overlap in a planar view covered with a transparent conductive material.

8. A radio wave control board capable of emitting incident radio waves in a predetermined direction, comprising a plurality of unit structures arranged on a first surface, wherein the unit structures comprise: a first substrate; a first electrode provided on the first substrate and formed in a mesh shape in a planar view; a second substrate provided opposite the first substrate; a second electrode provided on the second substrate and facing the first electrode and formed in a mesh shape in a planar view; and a liquid crystal layer provided between the first substrate and the second substrate, wherein at least one of the first electrode and the second electrode has at least a portion of an area where the first electrode and the second electrode overlap in a planar view covered with a transparent conductive material.

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