WO2023037428A1

WO2023037428A1 - Optically transparent antenna

Info

Publication number: WO2023037428A1
Application number: PCT/JP2021/032944
Authority: WO
Inventors: 弘樹萩原; 央丸山
Original assignee: 日本電業工作株式会社
Priority date: 2021-09-08
Filing date: 2021-09-08
Publication date: 2023-03-16

Abstract

The present invention includes a substrate 14 formed from an insulating material with translucency and antenna units 11 and 12 that are provided on a surface of the substrate 14 and are formed from a conductive material with translucency. Each of the antenna units 11 and 12 is configured such that the resistance value of a portion of the conductive material where power is concentrated, such as a portion near a feeding unit, becomes less than the resistance value of another portion where power is diffused.

Description

light transmission antenna

The present invention relates to a light transmission antenna.

There is a transmissive antenna that is configured to transmit light such as visible light by providing a transparent conductive film on a transparent base material. By using a transparent base material and a transparent conductive film, the transmissive antenna can suppress the visibility of the antenna and suppress deterioration of the appearance at the installation location of the antenna.

Patent Literature 1 discloses a transparent electromagnetic radiation element that has a radiating element that radiates electromagnetic waves in a certain frequency band, and that the radiating element is made of one or both of a tin-doped indium oxide (ITO) thin film and a fluorine-doped tin oxide (FTO) thin film. A transparent antenna is disclosed which is a conductive film, the transparent conductive film has a certain film thickness, a certain level or more of transmittance in the visible light wavelength region, and a certain level or less of sheet resistance.

Japanese Patent Publication No. 2009-533888

　In an antenna using a transparent conductive film, the surface resistance greatly affects the gain and power handling performance of the antenna, as well as the light transmittance of the transparent conductive film. Specifically, the higher the resistance value of the surface, the greater the loss and the lower the gain and power handling capability. On the other hand, the higher the resistance value of the surface of the transparent conductive film, the higher the total light transmittance, so the transparency increases and the visibility decreases.

Conventionally, through-beam antennas are configured so that the overall surface resistance is constant, so the resistance value of the entire antenna was lowered to improve the gain and power handling capability of the antenna. However, when the resistance value of the entire antenna is lowered, the light transmittance of the entire antenna is lowered and the visibility of the antenna is improved.

An object of the present invention is to improve the gain and power handling capability of a light-transmissive antenna, and to suppress the deterioration of the light-transmittance of the antenna as a whole.

The present invention for achieving the above objects includes a substrate formed of a light-transmitting insulating member, and an antenna section provided on the surface of the substrate and constructed of a light-transmitting conductive member. In addition, the antenna section is a light transmission type antenna characterized in that a portion of the conductive member where electric power is concentrated has a lower resistance value than other portions.
More specifically, the conductive member is composed of a mesh-like conductor, and the wires forming the mesh of the conductor are thicker in a portion where electric power is concentrated than in other portions.
Also, the conductive member is made of a mesh-like conductor, and the size of the mesh of the conductor is smaller in a part where electric power concentrates than in other parts.
Also, the conductive member is made of a film-like conductor, and the film thickness of the conductor is thicker at a portion where electric power is concentrated than at other portions.
Further, another aspect of the present invention for achieving the above object is to provide a substrate formed of an insulating member having translucency, and an antenna section provided on the surface of the substrate and constituted by a conductive member having translucency. and wherein the antenna section is configured such that a portion of the conductive member near the feeding portion has a lower resistance value than other portions.
More specifically, the conductive member is made of a mesh-like conductor, and the wires forming the mesh of the conductor are thicker at a portion near the power supply portion than at other portions.
Also, the conductive member is made of a mesh-like conductor, and the size of the mesh of the conductor is smaller at a portion near the power supply portion than at other portions.
Also, the conductive member is made of a film-like conductor, and the film thickness of the conductor is thicker at a portion near the power supply portion than at other portions.

According to the present invention, in a transmissive antenna, it is possible to improve the gain and power resistance of the antenna and to suppress the deterioration of the translucency of the entire antenna.

It is a figure which shows the installation example of a transmissive antenna. It is a figure which shows the structural example of a transmissive antenna. FIG. 4 is a diagram showing an example of setting resistance values at respective parts of the antenna section of the light transmission type antenna; FIG. 4 is a diagram comparing mesh-like conductors with different mesh sizes. FIG. 4 is a diagram comparing mesh-like conductors having different thicknesses of lines forming the mesh. FIG. 6A is a diagram showing how the temperature rises when electric power is applied to the light-transmitting antenna, and FIG. FIG. 6B is a diagram showing the temperature distribution in a transmissive antenna in which a uniform resistance value is set over the entire antenna section. FIG. 4 is a diagram showing another configuration example of a light transmission antenna;

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<Structure of Light Transmission Type Antenna>
FIG. 1 is a diagram showing an installation example of a light transmissive antenna. The transmissive antenna 10 is installed on the ceiling, wall surface, or the like of a house. The example shown in FIG. 1 shows an example in which the light transmissive antenna 10 is installed on the ceiling 100 . In FIG. 1 , the side of the ceiling 100 on which the light transmission type antenna 10 is installed is called the front side of the ceiling 100 . The transmissive antenna 10 is fixed to the ceiling 100 by means of legs 20 . A power line (not shown) for supplying power to the transmissive antenna 10 is wired on the back side of the ceiling 100 , and a part of the line is drawn into the foot portion 20 . The leg portion 20 incorporates a power supply board (not shown) that is connected to the terminal of the light transmissive antenna 10 . As a result, power is supplied from the power line behind the ceiling 100 to the transmissive antenna 10 through the legs 20 .

FIG. 2 is a diagram showing a configuration example of the light transmissive antenna 10. FIG. The transmissive antenna 10 includes a substrate 14 , and

antenna portions

11 and 12 and terminals 13 provided on the surface of the substrate 14 . The substrate 14 is a plate-shaped member made of an electrically insulating material having high visible light transmittance. The substrate 14 may be made of any material as long as it has high transparency to visible light and electrical insulation. For example, the substrate 14 can be formed using a material such as a highly translucent resin such as PET (Poly Ethylene Terephthalate) resin or glass. Further, the substrate 14 may have flexibility (flexibility).

The

antenna sections

11 and 12 are formed on one side surface of the substrate 14 by a translucent conductive member. The antenna section 11 is, for example, a radiation element corresponding to a target frequency band, and the antenna section 12 is, for example, an antenna GND connected to the ground (GND). The

antenna sections

11 and 12 have a shape corresponding to a target frequency band (for example, 1.7 GHz to 5 GHz). In the example shown in FIG. 2, the antenna section 11 has a shape that gradually widens from the root section (lower side in FIG. 2) where the terminal 13 is provided toward the tip section (upper side in FIG. 2). Two antenna units 12 are provided on both sides of the antenna unit 11 on the substrate 14 . The two antenna sections 12 extend in a direction orthogonal to the direction in which the tip of the antenna section 11 extends. Note that the shapes of the

antenna portions

11 and 12 may be appropriately determined according to the target frequency band, and are not limited to the shape shown in FIG.

The terminal 13 is connected to the power supply board of the leg portion 20 in a state where the light transmission type antenna 10 is attached to the leg portion 20 and supplies power to the

antenna portions

11 and 12 . The terminal 13 consists of a terminal 13a provided at the base of the antenna section 11 and two terminals 13b provided at each of the two antenna sections 12. As shown in FIG. The terminal 13 a is a power feeding section that supplies power to the antenna section 11 , and the terminal 13 b is a power feeding section that supplies power to the antenna section 12 .

As the conductive members forming the

antenna parts

11 and 12, various materials that can be used in existing light-transmitting antennas, such as mesh-like conductors and film-like conductors, can be used. In the following, a case where a mesh-like conductor (hereinafter referred to as a "mesh-like conductor") is mainly used will be described as an example. As a conductive material forming the mesh-shaped conductor used for the

antenna portions

11 and 12, a material having high electrical conductivity and being easily processed into a mesh-like shape is used. For example, copper (Cu), silver (Ag), aluminum (Al), etc. can be used. The mesh pattern of the mesh conductor is not particularly limited, but in the example shown in FIG. 2, an orthogonal grid pattern is used.

The mesh conductor of the light transmission antenna 10 is manufactured by etching a conductor material such as a copper (Cu) film or a silver (Ag) film formed on the substrate 14, for example. In this manufacturing method, first, etching masks for forming the

antenna portions

11 and 12 are generated. Specifically, this etching mask is formed by cutting a conductive material into the shape of the

antenna portions

11 and 12, and has a mesh pattern forming surfaces within the shape of the

antenna portions

11 and 12. The portion is formed so that the conductive material remains without being processed into a mesh shape. Then, using this etching mask, the conductive material formed on the substrate 14 is etched. By doing so, the

antenna portions

11 and 12 having a mesh shape and a desired outer diameter and the terminal 13 are integrally formed by one etching.

As another manufacturing method, for example, a method of processing a conductive material that has been processed into a mesh shape in advance into the shape of the

antenna portions

11 and 12 and attaching them to the substrate 14 is conceivable. In this case, the non-mesh terminal 13 is formed separately from the

antenna portions

11 and 12 and is attached to the substrate 14 while being connected to the

antenna portions

11 and 12 . In addition, various existing methods can be used as a method for manufacturing the light transmission type antenna 10 .

<Mesh pattern of antenna part>
If the resistance value of the conductive member is uniform throughout the

antenna sections

11 and 12 of the light transmission type antenna 10, local concentration of electric power occurs depending on the shape thereof. Suppressing the loss of power at locations where power concentrates greatly contributes to the improvement of the power handling capability and gain of the antenna. Therefore, in the present embodiment, the conductive members of the

antenna units

11 and 12 are configured so that the electric power concentrates at a portion having a lower resistance value than other electric power diffused portions. As a result, the current is dispersed over a wide area of the

antenna units

11 and 12, and local concentration of power is suppressed. In this way, the concentration of electric power at specific portions of the

antenna portions

11 and 12 is suppressed, thereby improving the power handling capability and gain of the antenna. A decrease in translucency of the

portions

11 and 12 can be suppressed. Also, by reducing local power concentration in the

antenna units

11 and 12, PIM (Passive Intermodulation) of the

antenna units

11 and 12 is expected to be improved.

Which part of the

antenna units

11 and 12 the electric power concentrates depends on the shape of the

antenna units

11 and 12 . In general, electric power is likely to be concentrated at a portion near a power supply portion or at the edge of a conductive member. In order to more specifically and accurately identify power concentration locations, a simulation may be performed to estimate the power concentration locations according to the shape of the

antenna units

11 and 12, or actual measurements of the actual light transmission antenna 10 may be performed. A location where power concentration occurs may be determined.

FIG. 3 is a diagram showing a setting example of resistance values at respective portions of the

antenna sections

11 and 12 of the light transmission type antenna 10. FIG. In the example shown in FIG. 3, the antenna section 11 is divided into three regions (a) to (c) and a terminal 13a, and the antenna section 12 is divided into two regions (d) and (e) and a terminal. 13b. In the illustrated example, the resistance values are set for the regions (a) to (e) shown in FIG.

In the antenna section 11 shown in FIG. 3, the area (c) is the closest to the terminal 13a, which is the feeding section, among the three areas. Therefore, the resistance value of the region (c) is set to be lower than that of the regions (a) and (b). In addition, both the area (a) and the area (b) are far from the terminal 13a, which is the feeding section, but since the area (b) is located on both sides of the antenna section 11, it is not as far as the area (c). There is more power concentration than in region (a), although there is none. On the other hand, the region (a) also includes the tip side edge of the antenna section 11, but since it is far from the terminal 13a, which is the feeding section, significant power concentration does not occur. Therefore, the resistance value of the region (b) is set to be lower than that of the region (a). Therefore, regarding the antenna section 11,

Area (a) > Area (b) > Area (c)

A resistance value for each region is set so that

Further, in the antenna section 12 shown in FIG. 3, the area (d) is the closest to the terminal 13b, which is the feeding section, among the two areas. Therefore, the resistance value of the region (d) is set to be lower than that of the region (e). Therefore, regarding the antenna section 12,

area (e) > area (d)

A resistance value for each region is set so that The resistance values of the regions (a) to (c) and the resistance values of the regions (d) and (e) can be set individually. and the region (d) may have the same resistance value, and the second region (b) and the region (e) may have the same resistance value. In this case, the resistance value of each region is

area (a) > area (b) = area (e) > area (c) = area (d)

becomes.

Next, a method of setting the resistance value when the

antenna sections

11 and 12 are made of a mesh conductor will be described. In order to make the resistance value of the conductive member different depending on the location of the

antenna parts

11 and 12, a method of making the surface resistance of the conductive member different can be taken. When a mesh-like conductor is used as the conductive member, each mesh-like conductor is made to have different thicknesses of lines forming the mesh or different mesh sizes, so that each mesh-like conductor Different resistance values can be used.

FIG. 4 is a diagram comparing mesh conductors with different mesh sizes. Let the mesh-like conductor on the left side in FIG. Here, in the reference mesh A, the width (thickness) of the lines forming the mesh is set to 10 μm, and the interval between the lines is set to 100 μm. On the other hand, the mesh-like conductor on the right side shown in FIG. Here, in the low-resistance mesh B, the width (thickness) of the lines forming the mesh is 10 μm, and the interval between the lines is 50 μm. Comparing the reference mesh A and the low-resistance mesh B, the low-resistance mesh B has a line interval of 1/2 that of the reference mesh A. Therefore, the mesh size of the low resistance mesh B is 1/4 of the mesh size of the reference mesh A. In this way, the low-resistance mesh B has a surface resistance smaller than that of the reference mesh A by narrowing the line spacing in the mesh-like conductor.

FIG. 5 is a diagram comparing mesh-like conductors having different thicknesses of lines forming the mesh. The mesh-like conductor on the left side shown in FIG. 5 is the reference mesh A, which is the same as the reference mesh A shown in FIG. On the other hand, the mesh-like conductor on the right side shown in FIG. Here, in the low-resistance mesh C, the width (thickness) of the lines forming the mesh is 30 μm, and the interval between the lines is 100 μm. Comparing the reference mesh A and the low resistance mesh C, the low resistance mesh C has a line width (thickness) three times that of the reference mesh A. In this way, by increasing the wire thickness of the mesh-like conductor, the low-resistance mesh C has a surface resistance smaller than that of the reference mesh A. As shown in FIG.

In the examples shown in FIGS. 4 and 5, the surface resistance of the low-resistance mesh C is smaller than that of the low-resistance mesh B and the low-resistance mesh C. As shown in FIG. Therefore, the surface resistance of the reference mesh A, the low-resistance mesh B, and the low-resistance mesh C is

Reference mesh A > low resistance mesh B > low resistance mesh C

becomes. It should be noted that the numerical values of the thickness and spacing of the mesh conductors shown in FIGS. 4 and 5 are merely examples for comparison. In practice, it is only necessary to select meshes of appropriate size for each part according to the shape of the

antenna parts

11 and 12 and the set resistance value.

Here, referring to the light transmission type antenna 10 shown in FIG. 2, the

antenna parts

11 and 12 are mesh-like conductors with different meshes for each region corresponding to the regions (a) to (e) shown in FIG. is shown to be constructed using As an example, a mesh with a line width of 0.03 mm and a line spacing of 0.3 mm is used in regions (c) and (d), and a line width of 0 is used in regions (b) and (e). A mesh with a line width of 0.03 mm and a line spacing of 0.5 mm is used, and in region (a) a mesh with a line width of 0.03 mm and a line spacing of 0.8 mm is used. Each region is distinguished by the code of the corresponding region in FIG.

By applying such a mesh, the resistance values of the regions (c) and (d) are the lowest, the resistance values of the regions (b) and (e) are the next lowest, and the resistance value of the region (a) is The resistance value of the

entire antenna units

11 and 12 is set so that Here, an example is shown in which the resistance value of each region is changed by changing only the distance between lines without changing the line width, but as described above, the resistance value of each region can be changed by changing the line width. They may be different, or both the line width and line spacing may be different to make the resistance value of each region different.

FIG. 6 is a diagram showing how the temperature rises when power is applied to the transmissive antenna 10. FIG. FIG. 6(A) shows the temperature distribution in the light transmission type antenna 10 of the present embodiment in which the

antenna portions

11 and 12 are set with multistage resistance values, and FIG. FIG. 10 is a diagram showing temperature distribution in a transmissive antenna in which various resistance values are set; Comparing the temperature distributions of FIGS. 6(A) and 6(B), FIG. 6(A) has a flat temperature rise over a wide range, and the temperature difference is higher than that of FIG. 6(B). Less is. In other words, this means that power is widely diffused over the

entire antenna sections

11 and 12, and concentration of power on a specific portion is suppressed. Therefore, it is possible to suppress the deterioration of the translucency of the

antenna sections

11 and 12 caused by increasing the resistance value of the

entire antenna sections

11 and 12 in order to deal with concentration of electric power to a specific portion.

<Other mesh patterns of the antenna part>
As for the mesh-shaped conductors forming the

antenna sections

11 and 12, the light transmission type antenna 10 of FIG. However, if the mesh pattern in the mesh-like conductor of the

antenna parts

11 and 12 can be set with meshes of different sizes depending on the parts of the

antenna parts

11 and 12, the grid-like pattern shown in FIG. It is not limited and can take various patterns. As an example, a mesh that spreads radially from one point on the

antenna sections

11 and 12 may be applied.

FIG. 7 is a diagram showing another configuration example of the light transmissive antenna 10. FIG. In the example shown in FIG. 7, the

antenna portions

11 and 12 of the light transmission type antenna 10 have a mesh shape that applies a mesh that spreads radially from one point (point O in the drawing) of the terminal 13 toward the tips of the

antenna portions

11 and 12. It is composed of a conductor. In the mesh-like conductor, a straight line (hereinafter referred to as a "vertical line") extending radially at one end and converging toward a point O at the other end, and an arc centered at the point O are drawn. A network of curved lines (hereinafter referred to as "horizontal lines") is formed.

In the radial mesh shown in FIG. 7, the distance between the radial vertical lines increases as the distance from the point O increases. Therefore, as shown in FIG. 7, by setting the point O to the terminal 13, which is the power supply unit, the mesh becomes dense near the power supply unit where electric power concentration tends to occur, and the mesh becomes sparse as the distance from the power supply unit increases. It is easy to create a state In the example shown in FIG. 7, by changing the interval of the horizontal lines in two stages, a region with the lowest resistance value near the feeder, a region with the second lowest resistance value The region with the largest value is formed.

In the example shown in FIG. 7, the resistance value of each region in the

antenna sections

11 and 12 is varied depending on the line spacing, but as described with reference to FIGS. Each region may have a different resistance value, or both the line width and the line spacing may be different to make the resistance value of each region different.

<Formation of Antenna Part by Film-like Conductive Member>
The light transmissive antenna 10 described with reference to FIGS. 2 to 7 shows an example in which the

antenna portions

11 and 12 are made of a mesh conductor. However, as a conductive member that can be used as the

antenna portions

11 and 12 of the light transmission type antenna 10, a film-like conductor (hereinafter referred to as a "film-like conductor") may be used. As the film conductor, for example, a translucent metal thin film such as Ag-Stacked Film can be used.

By changing the thickness of the metal thin film, the surface resistance can be changed. Specifically, the thicker the film, the lower the surface resistance, and the thinner the film, the higher the surface resistance. Therefore, the film thickness is increased to reduce the resistance value at the portions where power is concentrated in the antenna portions 11 and 12 (for example, near the feeding portion), and the film thickness is decreased at other portions where power is diffused. The film conductor is configured to increase the resistance value.

Although the embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the above embodiments. For example, in the above embodiment, the meshes of the mesh-like conductors forming the

antenna units

11 and 12 are orthogonal lattice meshes (see FIG. 2) or radially expanding meshes (FIG. 7). ), but the mesh pattern is not limited to these patterns. Any pattern may be used as long as the mesh size can be adjusted for each specific portion of the

antenna units

11 and 12 to set a desired resistance value. can be In addition, the present invention includes various modifications and alternative configurations that do not depart from the scope of the technical idea of the present invention.

DESCRIPTION OF SYMBOLS 10... Light transmission type antenna, 11, 12... Antenna part, 13... Terminal, 14... Substrate, 20... Foot part, 100... Ceiling

Claims

a substrate formed of an insulating member having translucency;
an antenna unit provided on the surface of the substrate and configured by a conductive member having translucency;
A light transmission type antenna, wherein the antenna section is configured such that a portion of the conductive member where electric power concentrates has a lower resistance value than other portions.
3. The conductive member is composed of a mesh-like conductor, and in the portion where the electric power is concentrated, the thickness of the wire forming the mesh of the conductor is thicker than in other portions. 2. The light transmission antenna according to 1.
2. The apparatus according to claim 1, wherein said conductive member is composed of a mesh-like conductor, and the mesh size of said conductor is smaller in said part where said electric power is concentrated than in other parts. Optical transmission type antenna.
2. The light transmission according to claim 1, wherein the conductive member is composed of a film-like conductor, and the conductor is thicker at a portion where the electric power is concentrated than at other portions. type antenna.
a substrate formed of an insulating member having translucency;
an antenna unit provided on the surface of the substrate and configured by a conductive member having translucency;
A light transmission type antenna, wherein the antenna section is configured such that a portion of the conductive member near the feeding portion has a lower resistance value than other portions.
The conductive member is composed of a mesh-like conductor, and in a portion near the power supply portion, the thickness of the wire forming the mesh of the conductor is thicker than in other portions. Item 6. The light transmission antenna according to item 5.
6. The conductive member according to claim 5, wherein the conductive member is made of a mesh-shaped conductor, and the size of the mesh of the conductor is smaller at a portion near the power supply portion than at other portions. light transmission antenna.
6. The light according to claim 5, wherein the conductive member is composed of a film-shaped conductor, and the film thickness of the conductor is thicker at a portion near the power supply portion than at other portions. Transparent antenna.