Radio wave control plate

Abstract

This radio wave control plate is a radio wave control plate capable of emitting incident radio waves in a predetermined direction, and includes a plurality of unit structures arranged on a first surface. The unit structure includes a substrate and an electrode provided on the substrate and formed in a mesh shape in a 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 plate of the present disclosure is a radio wave control plate capable of emitting incident radio waves in a predetermined direction, and includes a plurality of unit structures arranged on a first surface, and the unit structures include a substrate and an electrode provided on the substrate and formed in a mesh shape when viewed in a plane.

[0006] FIG. 1 is a diagram for explaining an overview of a radio wave control plate. FIG. 2 is a top view showing a configuration example of a unit structure according to a first embodiment. FIG. 3 is a diagram for explaining ion migration. FIG. 4 is a diagram showing a configuration example of a unit structure according to a first example of a third embodiment. FIG. 5 is a diagram showing a configuration example of a unit structure according to a second example of the third embodiment. FIG. 6 is a diagram showing a configuration example of a unit structure according to a fourth embodiment.

[0007] 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.

[0008] [Outline] (Radio wave control board) An outline of the radio wave control board will be described with reference to Fig. 1. Fig. 1 is a diagram for explaining the outline of the radio wave control board.

[0009] The radio wave control plate 1 is configured to be able to emit incident radio waves in a predetermined direction. For example, when receiving radio waves transmitted from a base station, the radio wave control plate 1 is configured to reflect or refract 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 transmission (refraction) direction of the radio waves, but also both. In the present disclosure, reflection and refraction are sometimes collectively referred to as emission.

[0010] 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.

[0011] 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.

[0012] 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.

[0013] By varying the properties (e.g., size and shape) of each of the unit structures 10a to 10d, 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 the unit structures 10a to 10d can be varied. By varying the properties of each of the unit structures 10a to 10d so that the phase change amount increases (or decreases) sequentially, the radio wave control board 1 has a gradient of phase change amount. The gradient of phase change amount allows the radio wave control board 1 to reflect and / or refract the incident radio wave in a predetermined direction. For example, in the example shown in FIG. 1 , the size of the unit structure 10a is the largest, and the sizes of the unit structures 10b, 10c, and 10d are reduced in that order, thereby providing a gradient of phase change amount for the radio wave control board 1. In FIG. 1 , the shapes of the unit structures 10a to 10d are rectangular, but the shape of the unit structures is not limited to rectangular.

[0014] [First embodiment] (Unit structure) A configuration example of a unit structure according to the first embodiment will be described with reference to Fig. 2. Fig. 2 is a top view showing a configuration example of a unit structure according to the first embodiment.

[0015] As shown in Fig. 2, the unit structure 10 includes a substrate 2 and an electrode 12. In the examples shown in Figs. 2 and 3, for simplicity of explanation, the unit structure 10 is described as including one electrode 12, but the present disclosure is not limited thereto. The unit structure 10 may have a multi-stage structure in which multiple electrodes 12 are arranged in multiple stages. In the present disclosure, the multiple electrodes 12 may function as a resonator or a ground.

[0016] The substrate 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, because this makes the appearance of the substrate 2 less conspicuous. The substrate 2 formed of a dielectric material is also called a dielectric layer.

[0017] The electrode 12 is provided on the substrate 2. The electrode 12 extends in the XY plane. The electrode 12 is formed of a plurality of metal wires in a mesh (network) shape when viewed from the XY plane (planar view). The metal wires may contain elements other than metal elements. While the shape of the mesh (the gaps between the electrodes) is shown as a rectangle in FIG. 2 , it may be any other polygonal shape or may be composed of curves. That is, the present disclosure does not particularly limit the shape of the mesh. Furthermore, the size of the mesh may be the same for all of the meshes as shown in FIG. 2 , or may vary in part. The metal wires are formed of a material with a higher effective conductivity than a transparent conductive film (such as ITO (indium tin oxide)). Examples of materials with a higher effective conductivity than a transparent conductive film include, but are not limited to, silver, copper, and aluminum. From the viewpoint of conductivity, the metal wires are preferably silver or copper.

[0018] In the first embodiment, the electrodes 12 are formed in a mesh shape, making it difficult to recognize the electrodes 12 from the outside. Furthermore, the effective conductivity of the electrodes can be made higher than when a transparent conductive film is used as the electrode, which can reduce antenna loss in the radio wave control board.

[0019] Second Embodiment Next, a second embodiment will be described. In the first embodiment, the electrode 12 included in the unit structure 10 is formed in a mesh shape using a plurality of metal wires. In this case, ion migration may occur in the electrode 12.

[0020] Ion migration will be described with reference to Fig. 3. Fig. 3 is a diagram for explaining ion migration.

[0021] FIG. 3 is a cross-sectional view of the unit structure 10 shown in FIG. 2 . As shown in FIG. 3 , the electrode 12 is formed in a mesh shape, resulting in gaps between the metal wires and the adjacent metal wires. In this case, ion migration may occur between the metal wires and the adjacent metal wires. This may result in a short circuit between the electrode 12 and a signal line (not shown). Therefore, it is preferable to suppress the occurrence of ion migration. Ion migration is more likely to occur when the metal wires are made of a metal with relatively high conductivity, such as silver or copper. Ion migration is primarily caused by, for example, water molecules contained in the substrate 2. Specifically, when a voltage is applied to the electrode 12 while the electrode 12 is in contact with the substrate 2 containing water molecules, ion migration is likely to occur between the metal wire and the adjacent metal wire.

[0022] (Example of Electrode Configuration) In the second embodiment, the occurrence of ion migration is suppressed by forming the electrode 12 from an alloy. Specifically, in the second embodiment, the occurrence of ion migration is suppressed by forming the metal wire from an alloy containing at least one of copper, silver, gold, aluminum, nickel, titanium, chromium, molybdenum, and tantalum. Examples of the alloy according to the second embodiment include, but are not limited to, binary alloys such as an aluminum-molybdenum alloy (Al-Mo) or a silver-copper alloy (Ag-Cu), or ternary alloys such as a palladium alloy (Ag-Au-Pd). From the viewpoint of ion migration resistance, the alloy is preferably a ternary alloy.

[0023] In the second embodiment, it is possible to form a unit structure 10 in which the electrodes 12 are hard to recognize externally and the occurrence of ion magnetization is suppressed.

[0024] Third Embodiment Next, a third embodiment will be described. In the third embodiment, the electrode 12 is formed of a metal with high conductivity, such as silver, copper, or aluminum, and a protective film is provided to cover at least a portion of the electrode 12 in order to suppress the occurrence of ion migration. In the third embodiment, the conductivity of the electrode 12 can be higher than in the second embodiment.

[0025] (Configuration Example of Unit Structure) A configuration example of a unit structure according to a first example of the third embodiment will be described with reference to Fig. 4. Fig. 4 is a diagram showing a configuration example of a unit structure according to the first example of the third embodiment.

[0026] 4, a unit structure 10A according to a first example of the third embodiment includes a substrate 2, an electrode 12, and a protective layer 14. The protective layer 14 is a type of protective film.

[0027] The protective layer 14 is provided on the substrate 2 so as to cover the entire electrode 12. Therefore, the protective layer 14 exists between the metal wires constituting the electrode 12 and adjacent metal wires. The protective layer 14 may be formed of an insulator, a conductor, or a metal conductor. Examples of insulators include, but are not limited to, SiO2 or SiN. Examples of conductors include, but are not limited to, ITO or silver nanowires. Examples of metal conductors include, but are not limited to, molybdenum or cobalt.

[0028] In the first example of the third embodiment, the gap between the metal wire constituting the electrode 12 and the adjacent metal wire is filled with the protective layer 14, which can prevent water molecules from entering. Therefore, in the first example of the third embodiment, the occurrence of ion migration can be prevented between the metal wire constituting the electrode 12 and the signal line.

[0029] A configuration example of a unit structure according to a second example of the third embodiment will be described with reference to Fig. 5. Fig. 5 is a diagram showing a configuration example of a unit structure according to the second example of the third embodiment.

[0030] As shown in Fig. 5, a unit structure 10B according to a second example of the third embodiment includes a substrate 2, an electrode 12, and a plating layer 16. As shown in Fig. 5, the unit structure 10B differs from the unit structure 10A shown in Fig. 4 in that a plating layer 16 is formed instead of the protective layer 14. The plating layer 16 is a type of protective film.

[0031] The plated layer 16 is plated so as to cover the surface of the metal wire that constitutes the electrode 12. Examples of the material for the plated layer 16 include, but are not limited to, molybdenum and cobalt.

[0032] In the second example of the third embodiment, the plating layer 16 is formed on the surface of the metal wire that constitutes the electrode 12, which reduces adhesion of water molecules to the surface of the metal wire. Therefore, the second example of the third embodiment can suppress the occurrence of ion migration between the metal wire that constitutes the electrode 12 and the signal line.

[0033] The first and second examples of the third embodiment may be combined. That is, both the protective layer 14 and the plating layer 16 may be provided. Furthermore, the second and third embodiments may be combined. That is, the electrode 12 may be formed of an alloy, and a protective film may be further provided.

[0034] Fourth Embodiment A configuration example of a unit structure according to a fourth embodiment will be described with reference to Fig. 6. Fig. 6 is a diagram showing a configuration example of a unit structure according to the fourth embodiment.

[0035] 6, the unit structure 10C includes a substrate 2, an electrode 12, a protective layer 14, a liquid crystal layer 18, and an alignment film 20. The unit structure 10C differs from the unit structure 10A shown in FIG. 4 in that the unit structure 10C includes the liquid crystal layer 18 and the alignment film 20.

[0036] The liquid crystal layer 18 is provided on the protective layer 14. The relative dielectric constant of the liquid crystal layer 18 changes when a voltage is applied to the liquid crystal layer 18. In the fourth embodiment, the relative dielectric constant of the liquid crystal layer can be dynamically changed for each unit structure by adjusting the voltage applied to the liquid crystal layer 18. Therefore, in the fourth embodiment, the gradient of the phase change amount of the radio wave control plate 1 can be dynamically changed. As a result, in the fourth embodiment, the refraction direction and / or reflection direction of the radio wave can be dynamically changed.

[0037] The alignment film 20 is provided between the liquid crystal layer 18 and the protective layer 14. The alignment film 20 is a layer that controls the alignment angle of liquid crystal molecules contained in the liquid crystal layer 18 in a desired direction. The alignment film 20 is formed of a material containing polyimide, for example. Therefore, when the electrode 12 and the alignment film 20 are in contact with each other, moisture absorbed from the air by the alignment film 20 increases the possibility of ion migration occurring in the electrode 12.

[0038] In the unit structure 10C, a protective layer 14 is provided between the electrode 12 and the alignment film 20. The protective layer 14 reduces adhesion of moisture absorbed from the air by the alignment film 20 to the electrode 12. As a result, ion migration occurring in the electrode 12 can be suppressed. In the fourth embodiment, instead of or in addition to the protective layer 14, the electrode 12 may be made of an alloy as in the second embodiment, or a plating layer 16 as in the third embodiment may be provided on the surface of the electrode 12.

[0039] The present disclosure may also be configured as follows. (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 substrate; and an electrode provided on the substrate and formed in a mesh shape in a plan view. (2) The radio wave control board according to (1), including a protective film covering at least a portion of the electrode. (3) The radio wave control board according to (2), wherein the protective film is provided so as to cover the entire electrode. (4) The radio wave control board according to (2) or (3), wherein the protective film is plated on the surface of a metal wire constituting the electrode. (5) The radio wave control board according to any one of (2) to (4), wherein the protective film is formed of an insulator, a conductor, or a metal conductor. (6) The radio wave control board according to any one of (1) to (5), wherein the conductivity of the electrode is higher than the conductivity of a transparent conductive film. (7) The radio wave control board according to any one of (1) to (6), wherein the electrodes are formed of copper, silver, or aluminum. (8) The radio wave control board according to any one of (1) to (6), wherein the electrodes are formed of an alloy containing at least one of copper, silver, gold, aluminum, nickel, titanium, chromium, molybdenum, and tantalum. (9) The radio wave control board according to (8), wherein the electrodes are formed of a ternary alloy.

[0040] REFERENCE SIGNS LIST 1 Radio wave control plate 10, 10A, 10B, 10C Unit structure 12 Electrode 14 Protective layer 16 Plating layer 18 Liquid crystal layer 20 Alignment film

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, each of the unit structures comprising: a substrate; and an electrode provided on the substrate and formed in a mesh shape in a planar view.

2. The radio wave control board according to claim 1, further comprising a protective film covering at least a portion of the electrodes.

3. The radio wave control board according to claim 2, wherein the protective film is provided so as to cover the entire electrode.

4. The radio wave control board according to claim 2 or 3, wherein the protective film is plated on the surface of the metal wire that constitutes the electrode.

5. The radio wave control board according to any one of claims 2 to 4, wherein the protective film is formed of an insulator, a conductor, or a metal conductor.

6. The radio wave control board according to any one of claims 1 to 5, wherein the conductivity of the electrodes is higher than the conductivity of the transparent conductive film.

7. The radio wave control board according to any one of claims 1 to 6, wherein the electrodes are formed of copper, silver, or aluminum.

8. The radio wave control board according to any one of claims 1 to 6, wherein the electrodes are formed from an alloy containing at least one of copper, silver, gold, aluminum, nickel, titanium, chromium, molybdenum, and tantalum.

9. The radio wave control board according to claim 8, wherein the electrodes are formed from a ternary alloy.

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