Antenna

Abstract

A radiation unit (7) has: a first mesh pattern (101) including a first unit cell (C1) directly connected to a power supply unit (6), and a plurality of second unit cells (C2) connected to the power supply unit (6) via the first unit cell (C1); and a second mesh pattern (102) including a plurality of third unit cells (C3) connected to the power supply unit (6) via the first mesh pattern (101). The first wiring density of the first unit cell (C1) is higher than the third wiring density of the third unit cell (C3), and the second wiring density of the second unit cell (C2) is higher than the third wiring density of the third unit cell (C3).

Description

Antenna

[0001] The present invention relates to an antenna.

[0002] Conventionally, regarding electric field-type antennas such as dipole antennas, those disclosed in Patent Document 1, for example, are known.

[0003] Patent Document 1 discloses an antenna provided on a radio wave concentrating film (radio wave concentrating film 1). The radio wave concentrating film comprises a light-transmissive film-shaped base material (base material 10), and a mesh-shaped dipole antenna (first antenna layer 20A or second antenna layer 20B) provided on the base material. The dipole antenna is for high-frequency transmission and reception.

[0004] The dipole antenna comprises a pair of radiating portions (radiating portions 21, 22) opposed to each other, circuit portions (circuit portions 23, 24) respectively connected to the radiating portions, and feeding portions (feeding portions 25, 26) connected to the respective circuit portions and provided on the opposite side from the radiating portions.

[0005] In the radiating portions and the circuit portions, quadrangular antenna opening regions (antenna opening regions 29) form a mesh shape that is filled without gaps (see FIG. 3 of Patent Document 1). The antenna opening regions are formed by a plurality of antenna conductors (plurality of antenna conductors 30) linearly extending in a first direction (first direction a1), and a plurality of antenna conductors linearly extending in a second direction (second direction a2) orthogonal to the first direction.

[0006] Japanese Unexamined Patent Application Publication No. 2024-22571

[0007] In Patent Document 1, the pitch P2 in the second direction of multiple antenna conductors extending in the first direction is constant. The pitch P1 in the first direction of multiple antenna conductors extending in the second direction is constant. Pitch P2 is the same as pitch P1. The antenna aperture regions are arranged at a constant pitch in mutually orthogonal first directions (first direction a1) and second directions (second direction a2). As a result, all of the multiple antenna aperture regions included in the radiating section and circuit section are formed in the same rectangular shape (rhombic shape). That is, in the multiple antenna aperture regions, the aperture ratio of each region is the same. In this way, in the dipole antenna disclosed in Patent Document 1, the wiring density of the entire antenna (wiring density of multiple antenna conductors) is made uniform.

[0008] Incidentally, the distribution of current flowing through a dipole antenna is generally maximum at the location corresponding to the feed point. In other words, the current flowing through the dipole antenna is concentrated near the feed point.

[0009] In the configuration of Patent Document 1, in areas where current is concentrated, such as near the power supply section (hereinafter referred to as "current concentration points"), the wiring density of the entire antenna is uniform, which relatively increases the load due to the current. As a result, the antenna conductors tend to overheat in current concentration points, which could impair the reliability of the antenna.

[0010] This disclosure has been made in light of the above points, and its purpose is to ensure the reliability of the antenna.

[0011] To achieve the above objective, one embodiment of the present disclosure is an antenna comprising a film substrate, a power supply unit provided on the film substrate, and a radiating unit provided on the film substrate and electrically connected to the power supply unit. The radiating unit has a first mesh pattern including a first unit cell directly connected to the power supply unit and a plurality of second unit cells connected to the power supply unit via the first unit cell, and a second mesh pattern including a plurality of third unit cells connected to the power supply unit via the first mesh pattern. The first wiring density of the first unit cell is higher than the third wiring density of the third unit cell, and the second wiring density of the second unit cell is higher than the third wiring density of the third unit cell.

[0012] According to this disclosure, the reliability of the antenna can be guaranteed.

[0013] Figure 1 is an overall perspective view of an antenna according to the first embodiment of this disclosure. Figure 2 is a schematic diagram showing the positional relationship of each mesh pattern and the distribution of current flowing through the antenna in the antenna shown in Figure 1. Figure 3 is a partially enlarged view of part III shown in Figure 2. Figure 4 is a schematic cross-sectional view showing the cross-sectional structure of a metal nanowire. Figure 5 is a partially enlarged view of part V shown in Figure 2. Figure 6 is a partially enlarged view of part VI shown in Figure 2. Figure 7 is a partially enlarged view showing the configuration of the first unit cell. Figure 8 is a partially enlarged view showing the configuration of the second unit cell. Figure 9 is a partially enlarged view showing the configuration of the third unit cell. Figure 10 is a partially enlarged view showing the configuration of the fourth unit cell. Figure 11 is a schematic diagram relating to a measuring device for measuring the temperature rise of samples A and B. Figure 12 is a graph showing the results of measuring the maximum temperature of each sample A and B using thermography. Figure 13 is a diagram corresponding to Figure 7, showing a partially enlarged view of the configuration of the first unit cell according to Modification 1. Figure 14 is a diagram corresponding to Figure 7, showing a partially enlarged view of the configuration of the first unit cell according to Modification 2. Figure 15 is a diagram corresponding to Figure 7, showing a partially enlarged view of the configuration of the first unit cell of the antenna according to Modification 3. Figure 16 is a diagram corresponding to Figure 7, showing a partially enlarged view of the configuration of the first unit cell of the antenna according to Modification 4. Figure 17 is a diagram corresponding to Figure 7, showing a partially enlarged view of the configuration of the first unit cell of the antenna according to Modification 5. Figure 18 is a diagram corresponding to Figure 7, showing a partially enlarged view of the configuration of the first unit cell of the antenna according to Modification 6. Figure 19 is an overall perspective view of the antenna according to the second embodiment of this disclosure. Figure 20 is a diagram schematically showing the positional relationship of each mesh pattern in the antenna shown in Figure 19.

[0014] The embodiments of this disclosure will be described in detail below with reference to the drawings. The following descriptions of the embodiments are illustrative in nature and are not intended to limit this disclosure, its applications, or its uses.

[0015] [First Embodiment] Figure 1 shows an overall view of the antenna 1 according to the first embodiment of the present disclosure. The antenna 1 according to the first embodiment of the present disclosure has the function of generating radio waves in space or receiving radio waves from space. Figure 1 shows a dipole antenna as an example of the antenna 1 according to the first embodiment of the present disclosure. Although not shown, the antenna 1 may be a monopole antenna or an inverted F antenna.

[0016] The antenna 1 according to the first embodiment is applicable to equipment for performing communication between 3G and 5G, for example. The communication frequency of the antenna 1 is a predetermined frequency band, for example, 0.5 GHz to 30 GHz. Specifically, the communication frequencies of the antenna 1 are the 700 MHz band / 800 MHz band / 900 MHz band, 1.5 GHz band, 1.7 GHz band, 2 GHz band, 2.5 GHz band, 3.4 GHz band / 3.5 GHz band, 3.7 GHz band / 4.5 GHz band, 5.0 GHz band, 6.0 GHz band, or 28 GHz band, etc.

[0017] Here, in the first embodiment of this disclosure, for the sake of explanation, the direction from the left side of Figure 2 to the right side of the page (direction D1 shown in Figure 2) is defined as the "first direction". The direction from the bottom side of Figure 2 to the top side of the page (direction D2 shown in Figure 2) is defined as the "second direction".

[0018] As shown in Figures 1 and 2, the antenna 1 comprises a film substrate 2, a power supply section 6, and radiating sections 7a and 7b.

[0019] (Film Substrate) As shown in Figures 1 and 2, the film substrate 2 is formed in a substantially rectangular shape in plan view. The thickness of the film substrate 2 is, for example, 50 μm or more and 300 μm or less. The film substrate 2 is transparent.

[0020] As shown in Figure 4, the film substrate 2 has a first layer 3 and a second layer 4.

[0021] The third layer consists of a transparent resin material. Examples of transparent resin materials include PET (polyethylene terephthalate), PC (polycarbonate), COP (cycloolefin polymer), and COC (cycloolefin copolymer).

[0022] The second layer 4 is laminated on top of the first layer 3. The second layer 4 is a layer for forming the multiple grooves 5, which will be described later. The second layer 4 is made of a resin material that has insulating and permeable properties. The thickness of the second layer 4 is greater than the depth of the grooves 5, which will be described later.

[0023] Multiple grooves 5 are provided on the upper surface of the film substrate 2 (the upper surface of the second layer 4). The grooves 5 have a bottomed shape that is recessed downwards (in the thickness direction of the film substrate 2). The depth of the grooves 5 is set to, for example, 0.8 μm or more and 4.0 μm or less.

[0024] (Power supply section) As shown in Figures 1 and 2, the power supply section 6 is provided on the film substrate 2. The power supply section 6 is formed, for example, as a mesh pattern consisting of a plurality of fine metal wires 9 (described later) (not shown).

[0025] The power supply unit 6 is located on the upper surface of the film substrate 2, between adjacent radiating units 7a and 7b. A transmission wave is supplied to the power supply unit 6 from a communication device (not shown), for example, via a flexible wiring board (not shown).

[0026] (Radiating section) As shown in Figures 1 and 2, the radiating sections 7a and 7b are provided on the film substrate 2. The radiating section 7a and the radiating section 7b are separated in the first direction D1. Note that in Figure 2, for the sake of illustration, the metal wires 9 (described later) that constitute the radiating section 7a and the radiating section 7b are not shown.

[0027] The radial portion 7a is located on the right side of the paper in Figures 1 and 2. The radial portion 7b is located on the left side of the paper in Figures 1 and 2. The radial portion 7b is symmetrical to the radial portion 7a with respect to the center line CL shown in Figure 2.

[0028] In this embodiment, each of the radiating sections 7a and 7b is bent. Specifically, the radiating section 7a has an L-shape in a plan view. The radiating section 7b has an inverted L-shape in a plan view. In the following description, the bent portion of each of the radiating sections 7a and 7b will be referred to as the "bent portion" (see "reference numeral 8" shown in Figures 2, 3, and 6). In a dipole antenna for high-frequency transmission and reception, the bent portion 8 corresponds to the point where the current flowing through the radiating section 7 is concentrated.

[0029] The radiating portion 7a is electrically connected to the power supply portion 6 at approximately the center of the first direction D1 in the film substrate 2. The radiating portion 7b is electrically connected to the power supply portion 6 at approximately the center of the first direction D1 in the film substrate 2.

[0030] As shown in Figure 2, in the radiating section 7a, current flows from the position corresponding to the power supply section 6 toward the tip of the radiating section 7a (see the dashed arrow Ia shown in Figure 2). In the radiating section 7b, current flows from the position corresponding to the power supply section 6 toward the tip of the radiating section 7b (see the dashed arrow Ib shown in Figure 2).

[0031] Here, the waveform shown on the lower side of Figure 2 (indicated as CD) schematically shows the distribution of current flowing through the antenna 1 (radiating sections 7a and 7b) (hereinafter referred to as the "current distribution"). In this current distribution, the position corresponding to the feed point 6 becomes a so-called "antinode." That is, in each of the radiating sections 7a and 7b, the current concentrates near the feed point 6. On the other hand, in the current distribution, the tip ends of each of the radiating sections 7a and 7b become so-called "nodes." That is, in each of the radiating sections 7a and 7b, the current does not concentrate at positions far from the feed point 6.

[0032] The specific configuration of the radiating section 7a will be described below. Note that the specific configuration of the radiating section 7b is the same as that of the radiating section 7a, so a detailed explanation will be omitted.

[0033] As shown in Figure 3, the radial portion 7a is composed of a mesh pattern consisting of multiple metal nanowires 9. Each metal nanowire 9 is conductive. The multiple metal nanowires 9 extend along the first direction D1 and the second direction D2, respectively.

[0034] The line width of each metal wire 9 is, for example, 1 μm or more and 10 μm or less. The spacing between adjacent metal wires 9 is, for example, 50 μm or more and 600 μm or less. Although not shown in the figures, multiple metal wires 9 may extend in directions that intersect the first direction D1 and the second direction D2, respectively.

[0035] The metal wire 9 contains a conductive material embedded in the groove 5. As shown in Figure 4, the metal wire 9 has a conductive layer M1, an adhesion layer M2, and a seed layer M3.

[0036] The conductive layer M1 is embedded in the groove 5. The conductive layer M1 is laminated onto the adhesion layer M2 and seed layer M3 provided within the groove 5.

[0037] The adhesion layer M2 is an element that ensures the adhesion of the seed layer M3 to the groove 5. The adhesion layer M2 is a metal layer composed of a metal nitride or metal oxide containing at least one metal selected from the group consisting of Ti, Ni, Al, V, W, Ta, Si, Cr, Ag, Mo, Cu, and Zn. The adhesion layer M2 may be a single layer or a laminate of multiple layers with different compositions. The adhesion layer M2 is laminated as a thin film on the lower and side surfaces of the groove 5, for example, by vapor deposition or sputtering.

[0038] The seed layer M3 has the function of bonding the conductive layer M1 to the adhesion layer M2. Specifically, in this embodiment, the seed layer M3 functions as a cathode for laminating the conductive layer M1, which will be described later and contains copper (Cu), onto the adhesion layer M2 during an electroplating process to form the conductive layer M1. The seed layer M3 is laminated onto the adhesion layer M2 in the form of a thin film by, for example, vapor deposition or sputtering.

[0039] The conductive layer M1 is made of a conductive metal such as copper (Cu). The conductive layer M1 is formed by electroplating, electroless plating, vacuum deposition, or the like. When electroplating is performed, the conductive layer M1 and the seed layer M3 are formed integrally. This may result in a state where the interface between the conductive layer M1 and the seed layer M3 cannot be distinguished. Although copper (Cu) is suitable as the main component of the wiring, metals other than copper (for example, silver, gold, nickel, aluminum) may be contained.

[0040] As shown in FIG. 4, the fine metal wire 9 includes a blackened layer M4. The blackened layer M4 has a function to make the fine metal wire 9 not visible when viewed from the upper surface of the second layer 4. The blackened layer M4 may be omitted depending on the usage conditions of the antenna.

[0041] The blackened layer M4 is laminated on the upper surface of the conductive layer M1. From the viewpoint of suppressing the electrical resistance of the fine metal wire 9, the thickness of the blackened layer M4 is preferably, for example, 3 nm or more and 50 nm or less.

[0042] As shown in FIGS. 2 and 3, the radiating portion 7a includes a first mesh pattern 101, a second mesh pattern 102, and a third mesh pattern 103. In this embodiment, the area of the first mesh pattern 101 in plan view is smaller than the area of the second mesh pattern 102 in plan view (see FIG. 2). The area of the first mesh pattern 101 in plan view is, for example, 8% of the total area of the antenna.

[0043] (First Mesh Pattern) As shown in FIG. 2, the first mesh pattern 101 includes a position corresponding to an "antinode" of current distribution. As shown in FIGS. 3 and 5, the first mesh pattern 101 includes a first unit cell C1 and a plurality of second unit cells C2.

[0044] (First Unit Cell) As shown in FIGS. 3 and 5, the first unit cell C1 of the radiating portion 7a is adjacent to the feeding portion 6 on the right side of the drawing sheet in the figure. That is, the first unit cell C1 is located at a "node" of the current distribution (see FIG. 2).

[0045] The first unit cell C1 is directly connected to the feeder 6. That is, the first unit cell C1 is electrically connected to the feeder 6.

[0046] As shown in FIG. 5 and FIG. 7, the first unit cell C1 has a polygonal shape. Specifically, the first unit cell C1 is a quadrilateral shape (a square in this embodiment). Although not shown in the figures, the shape of the first unit cell C1 may be a rhombus or a rectangle.

[0047] The first unit cell C1 is constituted by a plurality of thin metal wires 9. Specifically, as shown in FIG. 7, the first unit cell C1 includes a first contour line 10 and a first auxiliary wiring 15. Each of the first contour line 10 and the first auxiliary wiring 15 is a part of the thin metal wire 9.

[0048] The first unit cell C1 has a predetermined aperture ratio. The aperture ratio of the first unit cell C1 is, for example, 90.0% or more and 100% or less. Note that the "aperture ratio" described above refers to a ratio obtained by subtracting the ratio (shadow ratio) that the plurality of thin metal wires 9 occupy in one cell from the total area (100%) of the cell.

[0049] (First Contour Line) As shown in FIG. 7, the first contour line 10 surrounds the first unit cell C1. Specifically, the first contour line 10 corresponds to the quadrilateral outline of the first unit cell C1.

[0050] The first contour line 10 includes a first main wiring 11, a second main wiring 12, a third main wiring 13, and a fourth main wiring 14. The first to fourth main wirings 11 to 14 are electrically conductive with each other.

[0051] The first main wiring 11 corresponds to one side on the left side of the drawing plane of the quadrilateral shape of the first unit cell C1 shown in FIG. 7. The first main wiring 11 extends linearly along the second direction D2.

[0052] The second main wiring 12 corresponds to one side on the upper side of the drawing plane of the quadrilateral shape of the first unit cell C1 shown in FIG. 7. The second main wiring 12 extends linearly along the first direction D1. Furthermore, the end portion of the first main wiring 11 and the end portion of the second main wiring 12 are located at the vertex V11 of the first unit cell C1 (the vertex located at the upper left side of the drawing plane in FIG. 7).

[0053] The third main wiring 13 corresponds to one side of the right side of the rectangle of the first unit cell C1 shown in Figure 7. That is, the third main wiring 13 faces the first main wiring 11 in the first direction D1. Furthermore, the third main wiring 13 extends linearly along the second direction D2. That is, the third main wiring 13 is parallel to the first main wiring 11.

[0054] The fourth main wiring 14 corresponds to one side of the lower edge of the rectangle of the first unit cell C1 shown in Figure 7. That is, the fourth main wiring 14 faces the second main wiring 12 in the second direction D2. Also, the fourth main wiring 14 extends linearly along the first direction D1. That is, the fourth main wiring 14 is parallel to the second main wiring 12.

[0055] (First auxiliary wiring) As shown in Figure 7, the first auxiliary wiring 15 is located inside the first contour line 10. The first auxiliary wiring 15 is connected to the first contour line 10. In this embodiment, the presence of the first auxiliary wiring 15 in the first unit cell C1 causes the direction of the current supplied from the power supply unit 6 to align with the diagonal of the first unit cell C1 (see arrow Ia shown in Figure 7).

[0056] The first auxiliary wiring 15 has a first end 15a and a second end 15b. In the first auxiliary wiring 15 illustrated in this embodiment, the first end 15a is located lower left of the page in Figure 7 than the second end 15b.

[0057] The first end 15a of the first auxiliary wiring 15 is in contact with the middle section of the first main wiring 11. The first end 15a is located approximately in the center of the first main wiring 11.

[0058] The second end 15b of the first auxiliary wiring 15 is in contact with the middle section of the second main wiring 12. The second end 15b is located approximately in the center of the second main wiring 12.

[0059] The first auxiliary wiring 15 extends in a curved shape from the first end 15a to the second end 15b. Specifically, as the first auxiliary wiring 15 moves from the first end 15a to the second end 15b, it curves outwards towards the vertex V11 (the intersection point of the end of the first main wiring 11 and the end of the second main wiring 21) located on the upper left side of Figure 7 of the first unit cell C1. This allows the current flowing through the first unit cell C1 to be smoothly and efficiently divided from the first end 15a to the second end 15b of the first auxiliary wiring 15.

[0060] Thus, in the first unit cell C1, by providing the first auxiliary wiring 15 separately from the first contour line 10, the current flowing through the first unit cell C1 is dispersed. As a result, the antenna radiation efficiency can be increased without significantly reducing the overall transmittance of the antenna 1, and the temperature rise due to localized current concentration can be suppressed. Furthermore, it becomes possible to prevent the breakage of the multiple metal wires 9 constituting the first unit cell C1 at positions corresponding to the "antinodes" of the current distribution in the antenna 1.

[0061] (Second Unit Cell) As shown in Figure 3, the multiple second unit cells C2 are connected to the power supply unit 6 via the first unit cell C1. That is, the multiple second unit cells C2 are electrically connected to the power supply unit 6 via the first unit cell C1. Furthermore, the multiple second unit cells C2 are positioned to include the "antinodes" of the current distribution.

[0062] As shown in Figure 8, the second unit cell C2 is polygonal. Specifically, the second unit cell C2 is quadrilateral (a square in this embodiment). Although not shown, the shape of the second unit cell C2 may also be a rhombus or a rectangle.

[0063] The second unit cell C2 is composed of multiple metal wires 9. Specifically, as shown in Figure 8, the second unit cell C2 has a second contour line 20 and at least one of the second auxiliary wirings 25 and 26. Both the second contour line 20 and the second auxiliary wirings 25 and 26 are parts of the metal wires 9.

[0064] The aperture ratio of the second unit cell C2 is the same as that of the first unit cell C1. That is, the aperture ratio of the second unit cell C2 is, for example, between 90.0% and 100%.

[0065] (Second contour line) As shown in Figure 8, the second contour line 20 encloses the second unit cell C2. Specifically, the second contour line 20 corresponds to the outline of the rectangular shape in the second unit cell C2. The second pitch of the second contour line 20 (dimension P2 shown in Figure 8) is equal to the first pitch of the first contour line 10 in the first unit cell C1 (dimension P1 shown in Figure 7).

[0066] The second contour line 20 includes the first main wiring 21, the second main wiring 22, the third main wiring 23, and the fourth main wiring 24. The first to fourth main wirings 21 to 24 are electrically conductive to each other.

[0067] The first main wiring 21 corresponds to one side of the left side of the rectangle of the second unit cell C2 shown in Figure 8. The first main wiring 21 extends linearly along the second direction D2.

[0068] The second main wiring 22 corresponds to one side of the upper part of the paper in the rectangular shape of the second unit cell C2 shown in Figure 8. The second main wiring 22 extends linearly along the first direction D1.

[0069] The ends of the first main wiring 21 and the second main wiring 22 are located at vertex V21 of the second unit cell C2 (the vertex located on the upper left side of the page in Figure 8).

[0070] The third main wiring 23 corresponds to one side of the right side of the rectangle in the second unit cell C2 shown in Figure 8. That is, the third main wiring 23 faces the first main wiring 21 in the first direction D1. Furthermore, the third main wiring 23 extends linearly along the second direction D2. That is, the third main wiring 23 is parallel to the first main wiring 21.

[0071] The fourth main wiring 24 corresponds to one side of the lower edge of the rectangle of the second unit cell C2 shown in Figure 8. That is, the fourth main wiring 24 faces the second main wiring 22 in the second direction D2. Also, the fourth main wiring 24 extends linearly along the first direction D1. That is, the fourth main wiring 24 is parallel to the second main wiring 22.

[0072] The ends of the third main wiring 23 and the fourth main wiring 24 are located at vertex V23 of the second unit cell C2 (the vertex located on the lower right side of the page in Figure 8).

[0073] (Second auxiliary wiring) As shown in Figure 8, the second auxiliary wirings 25 and 26 are located inside the second contour line 20. Specifically, the second auxiliary wiring 25 is located near vertex V21 in the second unit cell C2. The second auxiliary wiring 26 is located near vertex V23 in the second unit cell C2.

[0074] Each of the second auxiliary wirings 25 and 26 is connected to the second contour line 20. In this embodiment, the presence of the second auxiliary wirings 25 and 26 in the second unit cell C2 causes the direction of the current supplied from the power supply unit 6 to align with the diagonal of the first unit cell C1 (see arrow Ia shown in Figure 8).

[0075] The second auxiliary wiring 25 has a first end 25a and a second end 25b. In the second auxiliary wiring 25 illustrated in this embodiment, the first end 25a is located lower left of the page in Figure 8 than the second end 25b.

[0076] The first end 25a of the second auxiliary wiring 25 is in contact with the middle portion of the first main wiring 21. In this embodiment, the first end 25a of the second auxiliary wiring 25 is located approximately in the center of the first main wiring 21.

[0077] The second end 25b of the second auxiliary wiring 25 is in contact with the middle portion of the second main wiring 22. In this embodiment, the second end 25b of the second auxiliary wiring 25 is located approximately in the center of the second main wiring 22.

[0078] The second auxiliary wiring 25 extends in a curved shape from the first end 25a towards the second end 25b. Specifically, as the second auxiliary wiring 25 moves from the first end 25a towards the second end 25b, it curves outwards towards the vertex V21 of the second unit cell C2 (the intersection point of the end of the first main wiring 21 and the end of the second main wiring 22).

[0079] The second auxiliary wiring 26 has a first end 26a and a second end 26b. In the second auxiliary wiring 26 illustrated in this embodiment, the first end 26a is located lower left of the page in Figure 8 than the second end 26b.

[0080] The first end 26a of the second auxiliary wiring 26 is in contact with the middle portion of the fourth main wiring 24. In this embodiment, the first end 26a of the second auxiliary wiring 26 is located approximately in the center of the fourth main wiring 24.

[0081] The second end 26b of the second auxiliary wiring 26 is in contact with the middle portion of the third main wiring 23. In this embodiment, the second end 26b of the second auxiliary wiring 26 is located approximately in the center of the third main wiring 23.

[0082] The second auxiliary wiring 26 extends in a curved shape from the first end 26a toward the second end 26b. Specifically, as the second auxiliary wiring 26 moves from the first end 26a toward the second end 26b, it curves outwards toward the vertex V23 of the second unit cell C2 (the intersection point of the end of the third main wiring 23 and the end of the fourth main wiring 24).

[0083] Thus, in the second unit cell C2, the current flowing through the second unit cell C2 is dispersed by providing the second auxiliary wiring 26, 26 separately from the second contour line 20. As a result, the antenna radiation efficiency can be increased without significantly reducing the overall transmittance of the antenna 1, and the temperature rise due to localized current concentration can be suppressed. Furthermore, it becomes possible to prevent the breakage of the multiple metal wires 9 constituting the second unit cell C2 at positions corresponding to the "antinodes" of the current distribution in the antenna 1.

[0084] (Second Mesh Pattern) As shown in Figure 2, the second mesh pattern 102 includes positions corresponding to the "nodes" of the current distribution. The second mesh pattern 102 does not include positions corresponding to the "antinodes" of the current distribution.

[0085] As shown in Figure 3, the second mesh pattern 102 includes a plurality of third unit cells C3.

[0086] (Third Unit Cell) Multiple third unit cells C3 are connected to the power supply unit 6 via the first mesh pattern 101. That is, multiple third unit cells C3 are electrically connected to the power supply unit 6 via the first unit cell C1 and multiple second unit cells C2. In addition, multiple third unit cells C3 are arranged at positions that include the "nodes" of the current distribution (see Figure 2).

[0087] As shown in Figure 9, the third unit cell C3 is polygonal. Specifically, the third unit cell C3 is quadrilateral (a square in this embodiment). Although not shown, the shape of the third unit cell C3 may also be a rhombus or a rectangle.

[0088] The third unit cell C3 is composed of multiple metal wires 9. Specifically, as shown in Figure 9, the third unit cell C3 has a third contour line 30. The third contour line 30 is part of the metal wires 9. The third unit cell C3 does not have auxiliary wiring.

[0089] The aperture ratio of the third unit cell C3 is, for example, 90.0% or more and 100% or less. However, as mentioned above, since the third unit cell C3 does not have auxiliary wiring, the aperture ratio of the third unit cell C3 is higher than that of the first unit cell C1 and the second unit cell C2.

[0090] (Third contour line) As shown in Figure 9, the third contour line 30 encloses the third unit cell C3. Specifically, the third contour line 30 corresponds to the outline of the rectangle in the third unit cell C3. The third pitch of the third contour line 30 (dimension P3 shown in Figure 9) is equal to the first pitch of the first contour line 10 in the first unit cell C1 (dimension P1 shown in Figure 7).

[0091] The third contour line 30 includes the first main wiring 31, the second main wiring 32, the third main wiring 33, and the fourth main wiring 34. The first to fourth main wirings 31 to 34 are electrically conductive to each other.

[0092] The first main wiring 31 corresponds to one side of the left side of the rectangle of the third unit cell C3 shown in Figure 9. The first main wiring 31 extends linearly along the second direction D2.

[0093] The second main wiring 32 corresponds to one side of the upper part of the paper in the rectangular shape of the third unit cell C3 shown in Figure 9. The second main wiring 32 extends linearly along the first direction D1.

[0094] The third main wiring 33 corresponds to one side of the right side of the rectangle in the third unit cell C3 shown in Figure 9. That is, the third main wiring 33 faces the first main wiring 31 in the first direction D1. The third main wiring 31 extends linearly along the second direction D2. That is, the third main wiring 33 is parallel to the first main wiring 31.

[0095] The fourth main wiring 34 corresponds to one side of the lower edge of the rectangle of the third unit cell C3 shown in Figure 9. That is, the fourth main wiring 34 faces the second main wiring 32 in the second direction D2. Also, the fourth main wiring 34 extends linearly along the first direction D1. That is, the fourth main wiring 34 is parallel to the second main wiring 32.

[0096] (Characteristic Configuration of the First Mesh Pattern) A characteristic configuration of the first mesh pattern 101 is that the first wiring density of the first unit cell C1 is higher than the third wiring density of the third unit cell C3. Also, the second wiring density of the second unit cell C2 is higher than the third wiring density of the third unit cell C3. Due to this relationship between the first and third wiring densities, the wiring density of the first mesh pattern 101, which is located near the feed point 6, is higher than the wiring density of the second mesh pattern 102, which is located far from the feed point 6. In other words, the sheet resistance of the first mesh pattern 101 is lower than the sheet resistance of the second mesh pattern 102. As a result, for example in a dipole antenna, it is possible to suppress the load due to current at the current concentration point near the feed point 6. As a result, heat generation of the first mesh pattern 101 (specifically, the multiple fine metal wires 9 that constitute the first mesh pattern 101) is suppressed at the current concentration point. Therefore, for example in a dipole antenna for high-frequency transmission and reception, the reliability of the antenna 1 can be ensured.

[0097] Furthermore, as mentioned above, the area of ​​the first mesh pattern 101 in a plan view is smaller than the area of ​​the second mesh pattern 102 in a plan view (see Figure 2). In other words, the first mesh pattern 101, which has a high wiring density, occupies a relatively small area of ​​the entire antenna. This makes it possible to suppress a decrease in the overall transmittance of the antenna 1 while ensuring the reliability of the antenna 1.

[0098] Furthermore, in the first mesh pattern 101, the first auxiliary wiring 15 is provided separately from the first contour line 10 in the first unit cell C1, resulting in a higher first wiring density than the third wiring density. Similarly, in the second unit cell C2, the second auxiliary wiring 25 is provided separately from the second contour line 20, resulting in a higher second wiring density than the third wiring density. As a result, it becomes possible to suppress the load caused by current at current concentration points near the power supply section 6.

[0099] Furthermore, in this embodiment, since the first to third pitches P1 to P3 are equal to each other, the external dimensions of each of the first to third unit cells C1 to C3 are made common. As a result, differences in appearance between each of the first to third unit cells C1 to C3 are less likely to occur. Consequently, the overall visibility of the antenna 1 can be ensured.

[0100] Furthermore, by providing the first auxiliary wiring 15 within the first unit cell C1, the first and second main wirings 11 and 12 of the first unit cell C1 branch into two current paths: one path from the first main wiring 11 through the apex V11 of the first unit cell C1 to the second main wiring 12, and another path from the middle of the first main wiring 11 through the first auxiliary wiring 15 to the middle of the second main wiring 12. In particular, the current path via the first auxiliary wiring 15 results in a short circuit between the first main wiring 11 and the second main wiring 12. As a result, even if one or both of the first and second main wirings 11 and 12 are disconnected for any reason, the current flow to the first unit cell C1 can be guaranteed by the current path via the first auxiliary wiring 15.

[0101] Furthermore, by providing the first auxiliary wiring 15 within the first unit cell C1, it becomes possible to appropriately adjust the virtual direction of the current flowing within the first unit cell C1 (see symbol Ia in Figure 7). In this embodiment, the virtual direction of the current flowing within the first unit cell C1 is adjusted to align with the direction of the current flowing throughout the entire antenna 1. Specifically, the virtual direction of the current flowing within the first unit cell C1 aligns with the diagonal lines of the rectangular shape constituting the first unit cell C1.

[0102] (Third Mesh Pattern) As shown in Figure 2, the third mesh pattern 103 includes positions corresponding to the "antinodes" of the current distribution. As shown in Figures 3 and 6, the third mesh pattern 103 in this embodiment includes a plurality (three in the illustrated example) of fourth unit cells C4. Note that the third mesh pattern 103 only needs to include at least one fourth unit cell C4.

[0103] (Fourth Unit Cell) As shown in Figures 3 and 6, the multiple fourth unit cells C4 are connected to the power supply unit 6 via the first mesh pattern 101. That is, the multiple fourth unit cells C4 are electrically connected to the power supply unit 6 via the first unit cell C1 and the multiple second unit cells C2. Furthermore, the multiple fourth unit cells C4 are positioned to include the "antinodes" of the current distribution.

[0104] Multiple fourth unit cells C4 are located at the bent portion 8 of the radiating section 7 (see Figures 3 and 6). As described above, the bent portion 8 is a point where the current flowing through the radiating section 7 is concentrated. In other words, multiple fourth unit cells C4 are located at points where the current is concentrated throughout the entire radiating section 7.

[0105] As shown in Figure 10, the fourth unit cell C4 is polygonal. Specifically, the fourth unit cell C4 is quadrilateral (a square in this embodiment). Although not shown, the shape of the fourth unit cell C4 may also be a rhombus or a rectangle.

[0106] The fourth unit cell C4 is composed of multiple metal wires 9. Specifically, as shown in Figure 10, the fourth unit cell C4 has a fourth contour line 40 and fourth auxiliary wirings 45 and 46. Both the fourth contour line 40 and the fourth auxiliary wirings 45 and 46 are parts of the metal wires 9. Although the fourth unit cell C4 illustrated in this embodiment has both fourth auxiliary wirings 45 and 46, the fourth unit cell C4 only needs to have at least one of the fourth auxiliary wirings 45 and 46.

[0107] The aperture ratio of the fourth unit cell C4 is the same as that of the second unit cell C2. That is, the aperture ratio of the fourth unit cell C4 is, for example, between 90.0% and 100%.

[0108] Here, the specific configuration of the fourth contour line 40 is the same as the specific configuration of the second contour line 20 in the second unit cell C2. Also, the specific configuration of the fourth auxiliary wiring 45 and 46 is the same as the specific configuration of the second auxiliary wiring 25 and 26 in the second unit cell C2. For this reason, the explanation of the specific configurations of the fourth contour line 40 and the second auxiliary wiring 25 and 26 is omitted.

[0109] (Characteristic configuration of the third mesh pattern) A characteristic configuration of the third mesh pattern 103 is that the fourth wiring density of the fourth unit cell C4 is higher than the third wiring density of the third unit cell C3. Due to this configuration, the wiring density of the third mesh pattern 103 located near the bent portion 8 is higher than the wiring density of the second mesh pattern 102 located far from the bent portion 8. In other words, the sheet resistance of the third mesh pattern 103 is lower than that of the second mesh pattern 102. As a result, for example in a dipole antenna, it is possible to suppress the load due to current at the current concentration point near the bent portion 8. As a result, heat generation of the third mesh pattern 103 near the bent portion 8 is suppressed. Therefore, for example in a dipole antenna for high-frequency transmission and reception, the reliability of the antenna 1 can be ensured.

[0110] Furthermore, the third mesh pattern 103 is integrated with the first mesh pattern 101. This makes it possible to suppress the load due to current at current concentration points near the feed point 6 and the bent section 8 in a dipole antenna, for example. As a result, heat generation of the first mesh pattern 101 and the third mesh pattern 103 (specifically, the multiple fine metal wires 9 that make up the first mesh pattern 101 and the third mesh pattern 103) is suppressed. Therefore, the reliability of the antenna 1 can be ensured.

[0111] (Examples of measured temperature rise) Below, we will briefly describe examples of measured temperature rise related to the antenna 1 according to the first embodiment of this disclosure.

[0112] Using the measuring device E illustrated in Figure 11, the maximum temperature of each sample was measured by thermography as the input power (unit: dBm) was increased for each sample. Figure 12 shows the results of measuring the maximum temperature of each sample by thermography.

[0113] Here, the measuring device E illustrated in Figure 11 comprises a signal generator E1, an amplifier E2, a directional coupler E3, a power sensor E4, a power meter E5, and a thermograph E6. The symbols D in Figure 11 represent each sample being measured. The measurement temperature for this test was indoors (22°C).

[0114] In this measurement, two types of samples, Sample A and Sample B, were used. Samples A and B are different from the antenna 1 according to the first embodiment.

[0115] Sample A is an antenna that includes only the same configuration as the second mesh pattern 102 in the first embodiment (i.e., a configuration that does not include the first and third mesh patterns 101 and 103). In contrast, Sample B is an antenna that has the same configuration as antenna 1 according to the first embodiment. The wire width of the metal nanowires used in Samples A and B is 2 μm. In Samples A and B, the spacing (pitch) between adjacent metal nanowires is 400 μm.

[0116] According to the temperature curves showing the measurement results for samples A and B in Figure 12, for both samples A and B, as the input power (Pin) was increased, the temperature began to rise when the input power reached around 15 dBm.

[0117] At an input power of around 20 dBm, the temperature of sample A reached 29°C. In contrast, at an input power of around 20 dBm, the temperature of sample B reached 28°C. In other words, at an input power of around 20 dBm, the temperature of sample B was 1°C lower than that of sample A.

[0118] At an input power of around 23 dBm (corresponding to the maximum input power of a typical smartphone), the temperature of sample A reached 34°C. In contrast, at an input power of around 23 dBm, the temperature of sample B reached 32°C. In other words, in sample B, the temperature was 2°C lower than that of sample A at an input power of around 23 dBm.

[0119] At an input power of approximately 26.5 dBm, the temperature of sample A reached 50°C. In contrast, at an input power of approximately 26.5 dBm, the temperature of sample B reached 45°C. In other words, at an input power of approximately 26.5 dBm, the temperature of sample B was 5°C lower than that of sample A.

[0120] At an input power of approximately 28 dBm, the temperature of sample A reached 63°C. In contrast, at an input power of approximately 28 dBm, the temperature of sample B reached 55°C. In other words, at an input power of approximately 28 dBm, the temperature of sample B was 8°C lower than that of sample A.

[0121] Based on the above, the temperature curves showing the measurement results for samples A and B indicate that in sample B, the temperature was suppressed by 1°C to 8°C compared to sample A when the input power was between 20 dBm and 28 dBm. In other words, the temperature curve showing the measurement results for sample B showed an antenna efficiency difference of approximately 0.8 dBm compared to the temperature curve showing the measurement results for sample A. Thus, the results of this measurement show that the characteristic configuration of sample B (i.e., the first auxiliary wiring 15 in the first unit cell C1 and the second auxiliary wiring 25, 26 in the second unit cell C2 in the first and third mesh patterns 101, 103) can increase the antenna radiation efficiency and suppress the temperature rise due to localized current concentration.

[0122] Incidentally, in the range where the input power exceeded 28 dBm, some of the thin metal wires constituting sample A broke, causing it to cease functioning properly as an antenna, and thus the temperature dropped. In other words, in Figure 11, although the signal attempts to be input to the measurement target D (antenna), it is returned at the input terminal of measurement target D (antenna), and no signal is supplied to measurement target D (antenna). In contrast, when the input power was around 29 dBm, the temperature of sample B reached 62°C.

[0123] [Modification 1 of the First Embodiment] In the first embodiment described above, the first auxiliary wiring 15 is shown to curve and bulge toward the vertex V11 of the first unit cell C1 as it moves from the first end 15a to the second end 15b, but it is not limited to this form. For example, as shown in Figure 13, the first auxiliary wiring 15 may curve and bulge toward the center of the first unit cell C1 as it moves from the first end 15a to the second end 16b.

[0124] [Modification 2 of the First Embodiment] Although Modification 1 above shows a configuration in which one first auxiliary wiring 15 is provided, the embodiment is not limited to this configuration. For example, as shown in Modification 2 in Figure 14, multiple (two in the illustrated example) first auxiliary wirings 15, 15 may be provided. This makes it possible to further increase the first wiring density of the first unit cell C1. Note that in the first auxiliary wirings 15, 15 exemplified in Modification 2, the curvature of each curved portion is different from that of the others.

[0125] [Modification 3 of the First Embodiment] In the above embodiment and modifications 1 and 2, the first auxiliary wiring 15 is shown to extend in a curved shape from the first end 15a to the second end 15b, but it is not limited to this shape. For example, as shown in Modification 3 in Figure 15, the first auxiliary wiring 15 may extend in a straight line from the first end 15a to the second end 15b.

[0126] Specifically, in Modification 3, the extension direction of the first auxiliary wiring 15 from the first end 15a to the second end 15b is parallel to the extension direction of the diagonal in the first unit cell C1. This makes it possible to align the current path via the first auxiliary wiring 15 with the overall direction of the current flowing through the antenna 1 when the overall direction of the current flowing through the antenna 1 is aligned with the diagonal of the first unit cell C1. As a result, the antenna characteristics can be optimized.

[0127] [Modification 4 of the First Embodiment] In Modification 3 above, the first auxiliary wiring 15 is shown to extend in a straight line from the first end 15a to the second end 15b, but the embodiment is not limited to this. For example, as shown in Modification 4 in Figure 16, the first auxiliary wiring 15 may be bent from the first end 15a to the second end 15b. The configuration of the first contour line 10 is the same as in the above embodiment or Modification 3 above.

[0128] In the first unit cell C1 of Modification 4, the first auxiliary wiring 15 further comprises a first straight line 16, a third end 15c, and a second straight line 17. The first straight line 16 extends linearly in the first direction D1 from the first end 15a toward the third end 15c. The third end 15c is located at the end of the first straight line 16 opposite to the first end 15a. The second straight line 17 extends linearly in the second direction D2 from the third end 15c toward the second end 15b. The first straight line 16 and the fourth main wiring 14 are parallel. The second straight line 17 and the third main wiring 13 are parallel. Note that the first unit cell C1 of Modification 4 does not have the dummy wiring 18 of Modification 5, which will be described later.

[0129] In Modification 4, the shape of the area enclosed by the first main wiring 11, the second main wiring 12, the first straight line 16, and the second straight line 17 is a rectangle and is similar in shape to the first unit cell C1 (hereinafter simply referred to as the "similar rectangle"). In other words, the similar rectangle, except for its size, is identical in appearance to the first unit cell C1. As a result, the first auxiliary wiring 15 located in the first unit cell C1 becomes less conspicuous. Therefore, in Modification 4, the visibility of the entire antenna 1 is not affected.

[0130] [Modification 5 of the First Embodiment] Although Modification 4 above shows a configuration in which the first unit cell C1 does not have a dummy wiring 18, the embodiment is not limited to this configuration. For example, as shown in Modification 5 in Figure 17, a dummy wiring 18 may be provided inside the first unit cell C1. The configurations of the first contour line 10 and the first auxiliary wiring 15 are the same as in Modification 4 above.

[0131] In the first unit cell C1 of the modified example 5, the dummy wiring 18 is electrically nonconductive to both the first contour line 10 and the first auxiliary wiring 15. The dummy wiring 18 has a first dummy wiring 18a and a second dummy wiring 18b.

[0132] The first dummy wire 18a is parallel to the fourth main wire 14. The first dummy wire 18a is located on the extension of the first straight line 16. The first dummy wire 18a is separated from the third end 15c in the direction opposite to the first direction D1. Also, the first dummy wire 18a is separated from the third main wire 13 in the first direction D1.

[0133] The second dummy wiring 18b is parallel to the third main wiring 13. The second dummy wiring 18b is located on the extension of the second straight line 17. The second dummy wiring 18b is separated from the third end 15c in the second direction D2. Also, the second dummy wiring 18b is separated from the fourth main wiring 14 in the opposite direction to the second direction D2.

[0134] In this way, the dummy wiring 18 provided in the first unit cell C1 of the modified example 5 makes the first auxiliary wiring 15 located in the first unit cell C1 less conspicuous.

[0135] Furthermore, in Modification 5, by adding the first dummy wiring 18a and the second dummy wiring 18b, the area of ​​the first unit cell C1 is divided into multiple (four in the illustrated example) rectangular areas. The shape of each of these divided areas is the same as the shape (rectangular) of the area enclosed by the first main wiring 11, the second main wiring 12, the first straight line 16, and the second straight line 17. In other words, the shape of each of the above areas is similar to the first unit cell C1, and except for the size of the shape, it is the same as the appearance of the first unit cell C1. As a result, in Modification 5, the first auxiliary wiring 15 (first straight line 16 and second straight line 17) located in the first unit cell C1 can be made even less conspicuous.

[0136] [Modification 6 of the First Embodiment] In the first embodiment described above, the first auxiliary wiring 15 is shown to be located near vertex V11 of the first unit cell C1 (the intersection point of the end of the first main wiring 11 and the end of the second main wiring 21), but the embodiment is not limited to this. That is, the first auxiliary wiring 15 may be located near vertices other than vertex V11 of the first unit cell C1 (any of vertices V12, V13, or V14).

[0137] For example, as shown in Figure 18, the first auxiliary wiring 15 may be located closer to the vertex V13 of the first unit cell C1 (the intersection of the end of the third main wiring 13 and the end of the fourth main wiring 24). Specifically, the first auxiliary wiring 15 shown in this modified example curves outward towards the vertex V13 of the first unit cell C1 as it moves from the first end 15a to the second end 15b. Even with this modified example, the current flowing through the first unit cell C1 can be smoothly and efficiently divided from the first end 15a to the second end 15b of the first auxiliary wiring 15, just as in the first embodiment.

[0138] [Second Embodiment] Figures 19 and 20 show an antenna 201 according to the second embodiment of this disclosure. Unlike the antenna 1 (dipole antenna) shown in the first embodiment, the second embodiment illustrates a patch antenna. The antenna 201 according to the second embodiment will be described in detail below.

[0139] The antenna 201 according to the second embodiment comprises a film substrate 2, a power supply unit 202, a connection unit 203, and a radiating unit 204. The film substrate 2 in the second embodiment has the same configuration as the film substrate 2 described in the first embodiment. Therefore, a detailed description of the film substrate 2 will be omitted in the following description.

[0140] (Power supply unit) As shown in Figures 19 and 20, the power supply unit 202 is located on the upper surface of the film substrate 2, on the left side of the paper in the figures. The other configurations of the power supply unit 202 are the same as those described in the above embodiment.

[0141] (Connection part) As shown in Figures 19 and 20, the connection part 203 is provided on the film substrate 2. The connection part 203 is connected to the power supply part 202. The connection part 203 extends in a substantially strip shape along the first direction D1. The connection part 203 illustrated in Figure 19 has a mesh pattern containing multiple unit cells. The unit cells of the connection part 203 are the same as the fifth unit cell C5 described later.

[0142] (Radiating section) As shown in Figures 19 and 20, the radiating section 204 is provided on the film substrate 2. The radiating section 204 is composed of a mesh pattern consisting of a plurality of metal fine wires 9. Here, the metal fine wires 9 are the same as those described in the first embodiment above, so a detailed explanation is omitted. Also, in Figure 20, for the sake of illustration, the metal fine wires 9 that make up the radiating section 204 are not shown.

[0143] The radiating section 204 is located on the right side of the paper in Figures 19 and 20 relative to the connecting section 203. The radiating section 204 is connected to the power supply section 202 via the connecting section 203. Specifically, the radiating section 204 is connected to the connecting section 203 at its first side 204a, which will be described later.

[0144] The radial portion 204 is formed in a rectangular shape. Specifically, the radial portion 204 in this embodiment has a first side 204a, a second side 204b, a third side 204c, and a fourth side 204d.

[0145] The first side 204a is located on the left side of the paper in Figures 19 and 20. The first side 204a extends linearly along the second direction D2.

[0146] The second side 204b is located on the right side of the paper in Figures 19 and 20. That is, the second side 204b is opposite the first side 204a. The second side 204b extends linearly along the second direction D2.

[0147] The third side 204c is located on the lower side of the paper in Figures 19 and 20. The third side 204c extends linearly along the first direction D1.

[0148] The fourth side 204d is located on the upper side of the paper in Figures 19 and 20. That is, the fourth side 204d is opposite the third side 204c. The fourth side 204d extends linearly along the first direction D1.

[0149] In this embodiment of the antenna 201, current flows from the position corresponding to the power supply unit 202 (approximately the center of the paper in Figures 19 and 20) through the connection unit 203 toward the tip side (second side 204b side) away from the power supply unit 202.

[0150] In a patch antenna, the current distribution of the radiating section 204 (not shown) generally shows that the approximate center of the first direction D1 in the radiating section 204 is a so-called "antinode." Specifically, current concentrates at positions corresponding to the approximate center of the third side 204c and the fourth side 204d of the radiating section 204. On the other hand, the current distribution of the radiating section 204 shows that the first side 204a and the second side 204b of the radiating section 204 are so-called "nodes." That is, current does not concentrate on the first side 204a and the second side 204b of the radiating section 204.

[0151] As shown in Figures 19 and 20, the radiating section 204 has a fourth mesh pattern 104, a fifth mesh pattern 105, and a sixth mesh pattern 106.

[0152] In this embodiment, the area of ​​the fifth mesh pattern 105 in plan view is smaller than the area of ​​the fourth mesh pattern 104 in plan view. The area of ​​the sixth mesh pattern 106 in plan view is smaller than the area of ​​the fourth mesh pattern 104 in plan view. The area of ​​the fifth mesh pattern 105 and the sixth mesh pattern 106 in plan view is, for example, 13.3% of the total area of ​​the radial section 204.

[0153] (Fourth Mesh Pattern) As shown in Figure 19, the fourth mesh pattern 104 includes a plurality of fifth unit cells C5. The fourth mesh pattern 104 is directly connected to the connection part 203. Note that the fourth mesh pattern 104 does not include positions corresponding to the "antinodes" of the current distribution.

[0154] (Fifth Unit Cell) As shown in Figure 19, the multiple fifth unit cells C5 are connected to the power supply unit 202 via the connection part 203. That is, the multiple fifth unit cells C5 are electrically connected to the power supply unit 202 via the connection part 203. In addition, the multiple fifth unit cells C5 are arranged at positions that include the "nodes" of the current distribution in the patch antenna.

[0155] The fifth unit cell C5 is polygonal in shape. Specifically, the fifth unit cell C5 is quadrilateral (a square in this embodiment). Furthermore, the fifth unit cell C5 has an outline, similar to the third unit cell in the above embodiment. Note that the specific configuration of the fifth unit cell C5 is the same as that of the third unit cell C3 in the first embodiment, so a detailed explanation is omitted.

[0156] (Fifth Mesh Pattern) As shown in Figure 19, the fifth mesh pattern 105 includes a plurality of sixth unit cells C6. The fifth mesh pattern 105 is located approximately in the center of the third side 204c of the radiating portion 204. That is, the fifth mesh pattern 105 corresponds to an "antinode" of the current distribution. Note that the fifth mesh pattern 105 only needs to include at least one sixth unit cell C6.

[0157] (Sixth Unit Cell) As shown in Figure 19, the multiple sixth unit cells C6 are connected to the connection section 203 via the fourth mesh pattern 104. That is, the multiple sixth unit cells C6 are electrically connected to the connection section 203 via the multiple fifth unit cells C5.

[0158] The sixth unit cell C6 is located in the center of the third side 204c of the radiating section 204. That is, multiple sixth unit cells C6 are positioned in the patch antenna 201 at locations that include the "antinodes" of the current distribution.

[0159] The sixth unit cell C6 is polygonal in shape. Specifically, the sixth unit cell C6 is quadrilateral (a square in this embodiment). Furthermore, the sixth unit cell C6 has contour lines and auxiliary wiring, similar to the first unit cell C1 or the second unit cell C2 in the above embodiment.

[0160] The specific configuration of the sixth unit cell C6 is the same as that of the first unit cell C1 or the second unit cell C2 in the above embodiment, so a detailed explanation is omitted. Furthermore, the sixth unit cell C6 may be configured in the same manner as in the above modifications 1 to 5.

[0161] A characteristic feature of the fourth mesh pattern 104 is that the sixth wiring density of the sixth unit cell C6, located in the center of the third side 204c, is higher than the fifth wiring density of the fifth unit cell C5. In other words, the wiring density of the fifth mesh pattern 105, located near the center of the third side 204c (the center of the radiating section 204), is higher than the wiring density of the fourth mesh pattern 104, located far from the center of the third side 204c. Specifically, the sheet resistance of the fifth mesh pattern 105 is lower than that of the fourth mesh pattern 104. This makes it possible to suppress the load due to current at current concentration points in a patch-type antenna (near the center of the radiating section 204), for example. As a result, heat generation of the fifth mesh pattern 105 (specifically, the multiple metal fine wires 9 constituting the fifth mesh pattern 105) is suppressed at current concentration points. Therefore, the reliability of the antenna 201 (patch-type antenna) can be ensured.

[0162] (Sixth Mesh Pattern) As shown in Figure 19, the sixth mesh pattern 106 includes a plurality of seventh unit cells C7. The sixth mesh pattern 106 is located approximately in the center of the fourth side 204d of the radiating portion 204. That is, the sixth mesh pattern 106 corresponds to an "antinode" of the current distribution. Note that the sixth mesh pattern 106 only needs to include at least one seventh unit cell C7.

[0163] (Seventh Unit Cell) As shown in Figure 19, multiple seventh unit cells C7 are connected to the connection section 203 via the sixth mesh pattern 106. That is, multiple seventh unit cells C7 are electrically connected to the connection section 203 via multiple fifth unit cells C5.

[0164] The seventh unit cell C7 is located in the center of the fourth side 204d of the radiating section 204. That is, multiple seventh unit cells C7 are positioned in locations that include the "antinodes" of the current distribution in the patch antenna.

[0165] The seventh unit cell C7 is polygonal in shape. Specifically, the seventh unit cell C7 is quadrilateral (a square in this embodiment). Furthermore, the seventh unit cell C7 has contour lines and auxiliary wiring, similar to the first unit cell C1 or the second unit cell C2 in the above embodiment.

[0166] The specific configuration of the seventh unit cell C7 is the same as that of the first unit cell C1 or the second unit cell C2 in the first embodiment described above, so a detailed explanation is omitted. Furthermore, the seventh unit cell C7 may be configured in the same manner as in the modifications 1 to 5 described above.

[0167] A characteristic feature of the sixth mesh pattern 106 is that the sixth wiring density of the seventh unit cell C7, located in the center of the fourth side 204d, is higher than that of the fifth unit cell C5. In other words, the wiring density of the sixth mesh pattern 106, located near the center of the fourth side 204d, is higher than that of the fourth mesh pattern 104, located far from the center of the fourth side 204d. Specifically, the sheet resistance of the sixth mesh pattern 106 is lower than that of the fourth mesh pattern 104. This makes it possible to suppress the load caused by the current flowing through the antenna 201, for example, at the current concentration point of the patch-type antenna 201 (near the center of the radiating section 204). As a result, heat generation of the sixth mesh pattern 106 (specifically, the multiple fine metal wires 9 constituting the sixth mesh pattern 106) is suppressed at the current concentration point. Therefore, the reliability of the antenna 201 (patch-type antenna) can be ensured.

[0168] [Other Embodiments] In the embodiments described above, a configuration in which a conductive material is embedded in the groove 5 with a metal wire 9 has been shown, but the embodiment is not limited to this. Although not shown, the metal wire 9 may, for example, protrude upward from the upper surface of the film substrate 9 (the upper surface of the second layer 4).

[0169] [Summary] As the first disclosure, the antenna 1 comprises a film substrate 2, a power supply unit 6 provided on the film substrate 2, and a radiating unit 7 provided on the film substrate 2 and electrically connected to the power supply unit 6. The radiating unit 7 has a first mesh pattern 101 including a first unit cell C1 directly connected to the power supply unit 6 and a plurality of second unit cells C2 connected to the power supply unit 6 via the first unit cell C1, and a second mesh pattern 102 including a plurality of third unit cells C3 connected to the power supply unit 6 via the first mesh pattern 101. The first wiring density of the first unit cell C1 is higher than the third wiring density of the third unit cell C3. The second wiring density of the second unit cell C2 is higher than the third wiring density of the third unit cell C3.

[0170] In the first disclosure, the above configuration (particularly the relationship between the first and third wiring densities) results in a wiring density of the first mesh pattern 101 located near the feed point 6 being higher than that of the second mesh pattern 102 located farther from the feed point 6. That is, the sheet resistance of the first mesh pattern 101 is lower than that of the second mesh pattern 102. As a result, for example in a dipole antenna, it is possible to suppress the load due to current at the current concentration point near the feed point 6. Consequently, heat generation of the first mesh pattern 101 (specifically, the multiple metal fine wires 9 constituting the first mesh pattern 101) is suppressed at the current concentration point. Therefore, the reliability of the antenna 1 can be ensured.

[0171] As a second disclosure, the area of ​​the first mesh pattern 101 in a plan view is smaller than the area of ​​the second mesh pattern 102 in a plan view. In other words, the first mesh pattern 101, which has a high wiring density, occupies a relatively small area of ​​the entire antenna 1. This makes it possible to suppress a decrease in the overall transmittance of the antenna 1 while ensuring the reliability of the antenna 1.

[0172] As a third disclosure, the first unit cell C1 has a first contour line 10 surrounding the first unit cell C1 and a first auxiliary wiring 15 located inside the first contour line 10 and connected to the first contour line 10. The second unit cell C2 has a second contour line 20 surrounding the second unit cell C2 and a second auxiliary wiring 25 located inside the second contour line 20 and connected to the second contour line 20. The third unit cell C3 has a third contour line 30 surrounding the third unit cell C3. The second pitch p2 of the second contour line 20 is equal to the first pitch P1 of the first contour line 10. The third pitch P3 of the third contour line 30 is equal to the first pitch P1 of the first contour line 10.

[0173] In the third disclosure, in the first unit cell C1, the first auxiliary wiring 15 is provided separately from the first contour line 10, resulting in a higher first wiring density than the third wiring density. Similarly, in the second unit cell C2, the second auxiliary wiring 25 is provided separately from the second contour line 20, resulting in a higher second wiring density than the third wiring density. As a result, it becomes possible to suppress the load caused by current at current concentration points near the power supply section 6.

[0174] Furthermore, in the third disclosure, the size of the external dimensions of each of the first to third unit cells C1 to C3 is standardized because the first to third pitches P1 to P3 are equal to each other. As a result, differences in appearance between each of the first to third unit cells C1 to C3 are less likely to occur. Consequently, the visibility of the antenna 1 as a whole can be ensured.

[0175] As a fourth disclosure, the first unit cell C1 is polygonal in shape. The first contour line 10 includes a first main wiring 11 and a second main wiring 12. The ends of the first main wiring 11 and the ends of the second main wiring 12 are located at the vertex V11 of the first unit cell C1. The first auxiliary wiring 15 has a first end 15a and a second end 15b. The first end 15a is in contact with the middle portion of the first main wiring 11. The second end 15b is in contact with the middle portion of the second main wiring 12.

[0176] In the fourth disclosure, the first and second main wirings 11 and 12 branch into two current paths: one path from the first main wiring 11 through the apex V11 of the first unit cell C1 to the second main wiring 12, and another path from the middle of the first main wiring 11 through the first auxiliary wiring 15 to the middle of the second main wiring 12. In particular, the current path via the first auxiliary wiring 15 shorts the connection between the first main wiring 11 and the second main wiring 12. As a result, even if one or both of the first and second main wirings 11 and 12 are disconnected for any reason, the current flow to the first unit cell C1 can be ensured by the current path via the first auxiliary wiring 15.

[0177] As a fifth disclosure, the first auxiliary wiring 15 extends in a curved shape from the first end 15a to the second end 15b. This allows the current flowing through the first unit cell C1 to be smoothly and efficiently divided from the first end 15a to the second end 15b of the first auxiliary wiring 15.

[0178] As a sixth disclosure, the first unit cell C1 is rectangular in shape. The first auxiliary wiring 15 is straight. The extension direction of the first auxiliary wiring 15 from the first end 15a to the second end 15b is parallel to the extension direction of the diagonal in the first unit cell C1. This makes it possible to align the current path via the first auxiliary wiring 15 with the overall direction of the current flowing through the antenna 1 when the overall direction of the current flowing through the antenna 1 is along the diagonal of the first unit cell C1. As a result, the antenna characteristics can be optimized.

[0179] As a seventh disclosure, the first unit cell C1 is rectangular in shape. The first contour line 10 further includes a third main wiring 13 facing the first main wiring 11 and a fourth main wiring 14 facing the second main wiring 12. The first auxiliary wiring 15 further includes a straight first line 16 extending from the first end 15a, a third end 15c located at the end of the first line 16 opposite to the first end 15a, and a straight second line 17 extending from the third end 15c toward the second end 15b. The first line 16 and the fourth main wiring 14 are parallel. The second line 17 and the third main wiring 13 are parallel.

[0180] In the seventh disclosure, the shape of the area enclosed by the first main wiring 11, the second main wiring 12, the first straight line 16, and the second straight line 17 is a rectangle and is similar in shape to the first unit cell C1. That is, the similar rectangle, except for its size, is identical in appearance to the first unit cell C1. As a result, the first auxiliary wiring 15 located in the first unit cell C1 becomes less conspicuous. Therefore, in the seventh disclosure, it is possible to avoid affecting the visibility of the entire antenna 1.

[0181] As the eighth disclosure, the first unit cell C1 is provided with a dummy wiring 18. The dummy wiring 18 is electrically non-conductive to both the first contour line 10 and the first auxiliary wiring 15. This dummy wiring 18 makes the first auxiliary wiring 15 located in the first unit cell C1 even less conspicuous.

[0182] As a ninth disclosure, the dummy wiring 18 includes a first dummy wiring 18a parallel to the fourth main wiring 14 and a second dummy wiring 18b parallel to the third main wiring 13. The first dummy wiring 18a and the second dummy wiring 18b make the first auxiliary wiring 15 located in the first unit cell C1 even less conspicuous.

[0183] As a tenth disclosure, the radiating section 7 is bent. The radiating section 7 further has a third mesh pattern 103 which includes a fourth unit cell C4 that connects to the power supply section 6 via a first mesh pattern 101. The fourth unit cell C4 is located in the bent portion of the radiating section 7. The fourth wiring density of the fourth unit cell C4 is higher than the third wiring density of the third unit cell C3.

[0184] In the conventional dipole antenna disclosed in the prior art (for example, Patent Document 1), a bent portion (bent section) is formed at the connection point between the radiating section and the circuit section. In particular, in dipole antennas for high-frequency transmission and reception, the current flowing through the dipole antenna is concentrated near the bent section. On the other hand, in the prior art (Patent Document 1), as described above, the wiring density of the entire antenna is made uniform, so the load due to the current increases relatively not only near the feed point but also at the current concentration point near the bent section. As a result, in the prior art, the antenna conductors tend to overheat even near the bent section, which may impair the reliability of the antenna.

[0185] In contrast, in the tenth disclosure, since the fourth wiring density of the fourth unit cell C4 is higher than the third wiring density of the third unit cell C3, the wiring density of the third mesh pattern 103 located near the bent portion 8 is higher than the wiring density of the second mesh pattern 102 located far from the bent portion 8. That is, the sheet resistance of the third mesh pattern 103 is lower than the sheet resistance of the second mesh pattern 102. As a result, for example in a dipole antenna, it is possible to suppress the load due to current at the current concentration point near the bent portion 8. Consequently, heat generation of the third mesh pattern 103 near the bent portion 8 is suppressed. Therefore, for example in a dipole antenna for high-frequency transmission and reception, the reliability of the antenna 1 can be ensured.

[0186] As the eleventh disclosure, the third mesh pattern 103 is integrated with the first mesh pattern 101. This makes it possible to suppress the load due to current at current concentration points (near the feed point 6 and near the bend 8) in a dipole antenna, for example. As a result, heat generation of the first mesh pattern 101 and the third mesh pattern 103 (specifically, the multiple metal wires 9 that make up the first mesh pattern 101 and the third mesh pattern 103) is suppressed. Therefore, the reliability of the antenna 1 can be ensured.

[0187] As a twelfth disclosure, the antenna 201 includes a power supply section 202 provided on a film substrate 2, a connection section 203 provided on the film substrate 2 and connected to the power supply section 202, and a rectangular radiating section 204 provided on the film substrate 2 and connected to the power supply section 202 via the connection section 203. The radiating section 204 is directly connected to the connection section 203 and has a fourth mesh pattern 104 including a plurality of fifth unit cells C5, and a fifth mesh pattern 105 including a sixth unit cell C6 connected to the connection section 203 via the fourth mesh pattern 104. The radiating section 204 is connected to the connection section 203 at its first side 204a. The sixth unit cell C6 is located in the center of the third side 204c of the radiating section 204, which connects the first side 204a and the second side 204b opposite the first side 204a. The sixth wiring density of the sixth unit cell C6 is higher than the fifth wiring density of the fifth unit cell C5.

[0188] Incidentally, unlike a dipole antenna, the distribution of current flowing through a patch antenna is maximum at a position corresponding to the center of the radiating section. In other words, in a patch antenna, the current flowing through the antenna is concentrated near the center of the radiating section. On the other hand, in a patch antenna, if the wiring density of the entire antenna is uniform (i.e., the same configuration as the conventional technology described above), the load due to the current increases relatively near the center of the radiating section. As a result, in a patch antenna, the thin metal wires located at the current concentration point (near the center of the radiating section) are prone to overheating, which could impair the reliability of the antenna.

[0189] In contrast, in the twelfth disclosure, the sixth wiring density of the sixth unit cell C6 located in the center of the third side 204c is higher than the fifth wiring density of the fifth unit cell C5. That is, the wiring density of the fifth mesh pattern 105 located near the center of the third side 204c is higher than the wiring density of the fourth mesh pattern 104 located far from the center of the third side 204c. Specifically, the sheet resistance of the fifth mesh pattern 105 is lower than that of the fourth mesh pattern 104. This makes it possible to suppress the load caused by the current flowing through the antenna 201 at current concentration points (near the center of the radiating section 204) of a patch-type antenna. As a result, heat generation of the fifth mesh pattern 105 (specifically, the multiple metal fine wires 9 constituting the fifth mesh pattern 105) is suppressed at current concentration points. Therefore, the reliability of the antenna 201 can be ensured in the twelfth disclosure.

[0190] As a thirteenth disclosure, the radial section 204 has a sixth mesh pattern 106 including a seventh unit cell C7 located in the center of the fourth side 204d opposite the third side 204c. The seventh wiring density of the seventh unit cell C7 is higher than the fifth wiring density of the fifth unit cell C5.

[0191] In the thirteenth disclosure, the wiring density of the sixth mesh pattern 106, located near the center of the fourth side 204d, is higher than that of the fourth mesh pattern 104, located further from the center of the fourth side 204d. Specifically, the sheet resistance of the sixth mesh pattern 106 is lower than that of the fourth mesh pattern 104. This makes it possible to suppress the load due to current at current concentration points, for example, in a patch-type antenna, as in the twelfth disclosure. As a result, heat generation of the fifth mesh pattern 105 (specifically, the multiple metal wires 9 constituting the fifth mesh pattern 105) is suppressed at current concentration points. Therefore, in the twelfth disclosure, the reliability of the antenna 201 can be ensured.

[0192] This disclosure is applicable to industrial use as an antenna.

[0193] 1, 201: Antenna 2: Film substrate 6, 202: Power supply section 7a, 7b, 204: Radiating section 8: Bent section 9: Metal thin wire 15: First auxiliary wiring 15a: First end 15b: Second end 16: First straight line 17: Second straight line 18: Dummy wiring 18a: First dummy wiring 18b: Second dummy wiring 20: Second contour line 25, 26: Second auxiliary wiring 25a, 26a: First end 25b, 26b: Second end 30: Third contour line 40: Fourth contour line 45, 46: Fourth auxiliary wiring 101: First mesh pattern 102: Second mesh pattern 103: Third mesh pattern 104: Fourth mesh pattern 105: Fifth mesh pattern 106: Sixth mesh pattern 203: Connection section 204a: First side 204b: Second side 204c: Third side 204d: Fourth side C1: First unit cell C2: Second unit cell C3: Third unit cell C4: Fourth unit cell C5: Fifth unit cell C6: Sixth unit cell C7: Seventh unit cell

Claims

1. An antenna comprising: a film substrate; a power supply unit provided on the film substrate; and a radiating unit provided on the film substrate and electrically connected to the power supply unit, wherein the radiating unit has a first mesh pattern including a first unit cell directly connected to the power supply unit and a plurality of second unit cells connected to the power supply unit via the first unit cell; and a second mesh pattern including a plurality of third unit cells connected to the power supply unit via the first mesh pattern, wherein the first wiring density of the first unit cell is higher than the third wiring density of the third unit cell, and the second wiring density of the second unit cell is higher than the third wiring density of the third unit cell.

2. An antenna according to claim 1, wherein the area of ​​the first mesh pattern in a plan view is smaller than the area of ​​the second mesh pattern in a plan view.

3. An antenna according to claim 1 or 2, wherein the first unit cell has a first contour line surrounding the first unit cell and a first auxiliary wiring located inside the first contour line and connected to the first contour line; the second unit cell has a second contour line surrounding the second unit cell and a second auxiliary wiring located inside the second contour line and connected to the second contour line; the third unit cell has a third contour line surrounding the third unit cell; the second pitch of the second contour line is equal to the first pitch of the first contour line; and the third pitch of the third contour line is equal to the first pitch of the first contour line.

4. An antenna according to claim 3, wherein the first unit cell is polygonal in shape, the first contour line includes a first main wiring and a second main wiring, the end of the first main wiring and the end of the second main wiring are located at the vertices of the first unit cell, the first auxiliary wiring has a first end and a second end, the first end is in contact with the middle portion of the first main wiring, and the second end is in contact with the middle portion of the second main wiring.

5. An antenna according to claim 4, wherein the first auxiliary wiring extends in a curved manner from the first end toward the second end.

6. An antenna according to claim 4, wherein the first unit cell is rectangular in shape, the first auxiliary wiring is linear, and the extension direction of the first auxiliary wiring from the first end to the second end is parallel to the extension direction of the diagonal in the first unit cell.

7. An antenna according to claim 4, wherein the first unit cell is rectangular in shape, the first contour line further comprises a third main wiring facing the first main wiring and a fourth main wiring facing the second main wiring, the first auxiliary wiring further comprises a straight first line extending from the first end, a third end located at the end of the first line opposite to the first end, and a straight second line extending from the third end toward the second end, the first line and the fourth main wiring are parallel, and the second line and the third main wiring are parallel.

8. An antenna according to claim 7, wherein the first unit cell is provided with a dummy wiring, and the dummy wiring is electrically nonconductive to both the first contour line and the first auxiliary wiring.

9. The antenna according to claim 8, wherein the dummy wiring comprises a first dummy wiring parallel to the fourth main wiring and a second dummy wiring parallel to the third main wiring.

10. An antenna according to claim 1, wherein the radiating portion is bent, and the radiating portion further has a third mesh pattern including a fourth unit cell connected to the feeding portion via the first mesh pattern, the fourth unit cell is located in the bent portion of the radiating portion, and the fourth wiring density of the fourth unit cell is higher than the third wiring density of the third unit cell.

11. An antenna according to claim 10, wherein the third mesh pattern is integrated with the first mesh pattern.

12. An antenna comprising: a film substrate; a power supply unit provided on the film substrate; a connection unit provided on the film substrate and connected to the power supply unit; and a rectangular radiating unit provided on the film substrate and connected to the power supply unit via the connection unit, wherein the radiating unit has a fourth mesh pattern directly connected to the connection unit and including a plurality of fifth unit cells, and a fifth mesh pattern including a sixth unit cell connected to the connection unit via the fourth mesh pattern, the radiating unit is connected to the connection unit at its first side, the sixth unit cell is located in the center of the third side of the radiating unit that connects the first side and the second side opposite the first side, and the sixth wiring density of the sixth unit cell is higher than the fifth wiring density of the fifth unit cell.

13. An antenna according to claim 12, wherein the radiating portion has a sixth mesh pattern including a seventh unit cell located in the center of the fourth side opposite the third side, and the seventh wiring density of the seventh unit cell is higher than the fifth wiring density of the fifth unit cell.

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