Antenna device

Abstract

In an antenna device, electromagnetic waves are fully emitted in a target direction by suppressing reflection from a human body or other conductors. The antenna device (3) is an antenna device used in contact with or close to a human body or a conductor, and comprises an antenna pattern (17) and a supersurface layer (13). The supersurface layer (13) is a layer stacked on the antenna pattern (17) and arranged on the human body side. The supersurface layer (13) comprises a first low-loss film (20A) and a second low-loss film (20B), and a first supersurface (21A) and a second supersurface (21B) formed on the first low-loss film (20A) and the second low-loss film (20B), respectively.

Description

Technical Field

[0001] The present invention relates to an antenna device, in particular to an antenna device used near a human body or other conductors. Background Art

[0002] In recent years, various types of wearable computers are being developed, such as a watch type, a glasses type, a ring type, a shoe type, a pocket type, and a pendant type.

[0003] In addition, electronic devices such as earphones and headphones that are used close to the human body are also in use. And then, of course, electronic devices such as mobile phones and smart phones are also used close to or near the human body.

[0004] Various types of antennas are incorporated into the above-mentioned electronic devices for communication (for example, see Patent Document 1).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2018-170679 Summary of the Invention

[0008] Technical problem to be solved by the invention

[0009] The inventors of the present application have noticed that when a conventional electronic device with an antenna is used close to a human body (head or hand) or near a human body, the following problems may occur.

[0010] This problem occurs when radio waves emitted from an antenna are reflected by the human body, causing the antenna's transmission characteristics to be distorted. In this case, the radio waves are not sufficiently transmitted from the antenna in the target direction.

[0011] An object of the present invention is to enable an antenna device to sufficiently radiate radio waves in a target direction by suppressing reflection from a human body or other conductors.

[0012] Solutions for solving technical problems

[0013] Hereinafter, as means for solving the problem, a plurality of aspects will be described, and these aspects can be arbitrarily combined as needed.

[0014] An antenna device according to one aspect of the present invention is an antenna device used in contact with or close to a human body or a conductor, and includes an antenna and a metasurface layer.

[0015] The metasurface layer is a layer stacked on the antenna and arranged on the human body side. The metasurface layer includes a low-loss film and a metasurface formed on the low-loss film.

[0016] In this device, the metasurface layer is placed on the human body side of the antenna. Therefore, the metasurface layer suppresses reflection of electromagnetic waves from the human body, reducing the impact on the antenna. As a result, radio waves are effectively transmitted in the desired direction.

[0017] In this device, the metasurface is placed on a low-loss film. In this case, the use of a thin low-loss film enables a compact antenna device.

[0018] A plurality of low-loss films may be stacked.

[0019] The metasurface can be formed on each of the multiple low-loss films.

[0020] In this device, by forming a metasurface on multiple layers of low-loss films, even thin low-loss films can be constructed using a multi-stage circuit configuration to create an equivalent circuit of a filter that suppresses multiple reflections, thereby achieving impedance matching.

[0021] The thickness of the low-loss film can be 150 μm or less.

[0022] The metasurface can be a fractal shape.

[0023] In this device, wide-band characteristics can be easily achieved by increasing the fractal order of the metasurface.

[0024] Effects of the Invention

[0025] The antenna device according to the present invention can sufficiently radiate radio waves in a target direction by suppressing reflection from a human body. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic perspective view of a wireless headset incorporating the antenna device according to the first embodiment of the present invention.

[0027] Figure 2 Schematic diagram showing the layer structure of the antenna device.

[0028] Figure 3 Schematic diagram showing the cross-sectional structure of the antenna film.

[0029] Figure 4 is a schematic top view showing the planar position of the metasurface.

[0030] Figure 5 is the equivalent circuit diagram of the antenna device.

[0031] Figure 6 Schematic top view showing the planar position of the metasurface in a modified example.

[0032] Figure 7 It is a schematic diagram showing a cross-sectional structure of an antenna device according to a second embodiment.

[0033] Figure 8 is a schematic top view showing the planar positions of antennas and metasurfaces in various low-loss films.

[0034] Figure 9 It is a schematic diagram showing a cross-sectional structure of an antenna device according to a third embodiment.

[0035] Figure 10 is a schematic top view showing the planar positions of antennas and metasurfaces in various low-loss films.

[0036] Figure 11 It is a schematic diagram showing a cross-sectional structure of an antenna device according to a fourth embodiment.

[0037] Figure 12 is a schematic top view showing the planar positions of antennas and metasurfaces in various low-loss films.

[0038] Figure 13 It is a schematic diagram showing a cross-sectional structure of an antenna device according to a fifth embodiment.

[0039] Figure 14 is a schematic top view showing the planar position of the metasurface.

[0040] Figure 15 It is a schematic diagram showing a cross-sectional structure of an antenna device according to a sixth embodiment.

[0041] Figure 16 is a schematic top view showing the planar position of the metasurface.

[0042] Figure 17 is a schematic diagram showing a planar configuration of a ground.

[0043] Figure 18 Schematic top view showing the planar positions of antennas and metasurfaces in each low-loss film in the seventh embodiment.

[0044] Figure 19 Schematic top view of the metasurface in a modified example.

[0045] Figure 20 is a schematic top view of the metasurface in the eighth embodiment.

[0046] Figure 21 This is a schematic top view of the super surface in the ninth embodiment.

[0047] Figure 22 4 is a schematic top view of the super surface in the tenth embodiment.

[0048] Figure 23This is a schematic perspective view of smart glasses incorporating the antenna device according to the eleventh embodiment.

[0049] Figure 24 Schematic diagram showing the layer structure of the antenna device.

[0050] Figure 25 12 is a diagram showing a continuous blood glucose meter in which an antenna device according to a twelfth embodiment is incorporated, in use. 13 is a schematic perspective view of the continuous blood glucose meter.

[0051] Figure 26 Schematic diagram showing a cross-sectional structure of an antenna device.

[0052] Figure 27 is a schematic perspective view of an antenna device.

[0053] Figure 28 is a schematic top view of the antenna device.

[0054] Figure 29 is the equivalent circuit diagram of the antenna device. DETAILED DESCRIPTION

[0055] 1. First Implementation

[0056] (1) Basic structure

[0057] use Figure 1 The wireless headset 1 is described. Figure 1 This is a schematic perspective view of a wireless headset incorporating the antenna device according to the first embodiment of the present invention.

[0058] The wireless headset 1 includes an antenna device 3 and the like incorporated in a housing.

[0059] use Figure 2 The antenna device 3 will be described. Figure 2 Schematic diagram showing the layer structure of the antenna device.

[0060] exist Figure 2 The antenna device 3 is, for example, Blutooth (registered trademark), and comprises, from top to bottom in the figure, a cover layer 9, an adhesive layer 11, an overcoat layer 13 (an example of an overcoat layer), and a protective layer 15.

[0061] The supersurface layer 13 is composed of one or more low-loss films and a supersurface (described later). In the figure, an antenna pattern 17 (an example of an antenna) is formed on the upper surface of the supersurface layer 13. The supersurface layer 13 is arranged on the human body side relative to the antenna pattern 17. The supersurface layer 13 and the antenna pattern 17 described above constitute the antenna film 19.

[0062] The cover layer 9 is made of polycarbonate, for example, and has a thickness of 2 mm. The adhesive layer 11 is made of OCA, for example, and has a thickness of 25 μm. The antenna pattern 17 is made of copper, for example, and has a thickness of 3 μm.

[0063] (2) Detailed description of antenna film

[0064] use Figure 3 The antenna film 19 will be described. Figure 3 Schematic diagram showing the cross-sectional structure of the antenna film.

[0065] The antenna film 19 comprises, from the bottom of the figure, a first low-loss film 20A, a second low-loss film 20B, and a third low-loss film 20C. These films are stacked one on top of the other. Each low-loss film is made of, for example, PET or COP and has a thickness of 50 to 150 μm. The low-loss films are not particularly limited, as long as they are made of a material with low tan δ (low dielectric loss). The overall thickness of the low-loss films is preferably 150 μm or less.

[0066] The antenna pattern 17 is formed on the upper surface of the third low-loss film 20C.

[0067] A first electrode 21A1 of a first metasurface 21A is formed on the upper surface of the first low-loss film 20A. A second electrode 21B1 of a second metasurface 21B is formed on the upper surface of the second low-loss film 20B. The metasurface is, for example, copper with a thickness of 3 μm. Alternatively, the metasurface can be made of a conductive film transparent to visible light. Specifically, ITO (indium tin oxide) or a transparent conductive ink (e.g., silver nanowire ink) is used.

[0068] It should be noted that a metasurface is a "periodic structure with a wavelength shorter than that of an artificially constructed incident radio wave." Because the electromagnetic properties of a metasurface are determined by the resonance of the periodic structure, appropriately designed periodic structures can produce unique electromagnetic properties with refractive indices not found in nature.

[0069] A grounding layer 29 is formed on the lower surface of the first low-loss film 20A. The grounding layer 29 is a solid layer formed on the entire surface.

[0070] Gaps are provided between the first electrodes 21A1, for example, in a grid pattern. Capacitance components are generated in these gaps. Capacitance components are also generated between the first electrodes 21A1 and the ground 29. Furthermore, the first electrodes 21A1 themselves generate inductance components.

[0071] The same applies to the second electrode 21B1.

[0072] The first metasurface 21A has a first through-hole 21A2 connecting the first electrode 21A1 with the ground 29 . The second metasurface 21B has a second through-hole 21B2 connecting the second electrode 21B1 with the ground 29 .

[0073] Each first through hole 21A2 corresponds to one first electrode 21A1, penetrates the second low-loss film 20B and the first low-loss film 20A, and connects the first electrode 21A1 to the ground 29. Thus, an inductance component is generated in the first through hole 21A2.

[0074] The same applies to the second through hole 21B2.

[0075] use Figure 4 , the pattern configuration of the first super surface and the second super surface is described. Figure 4 is a schematic top view showing the planar position of the metasurface.

[0076] The first electrodes 21A1 and the second electrodes 21B1 are regular hexagonal. The first electrodes 21A1 and the second electrodes 21B1 are arranged alternately in rows and do not overlap when viewed from above. It should be noted that first through-holes 21A2 are provided corresponding to the first electrodes 21A1, and second through-holes 21B2 are provided corresponding to the second electrodes 21B1. There are no particular restrictions on the shape and placement of the electrodes. For example, the electrodes may partially overlap.

[0077] The structure described above realizes an EBG (Electromagnetic Band Gap) or an AMC (Artificial Magnetic Conductor) structure.

[0078] As described above, the use of an EBG structure allows the antenna thickness (for example, the thickness of antenna film 19) to be kept below λ / 4 while maintaining radiation efficiency. This is because, if the periodic structure is precisely tailored to the frequency, the phases of the electromagnetic waves incident on the EBG structure and those reflected by it can be aligned. If these phases are aligned, the electromagnetic waves reflected by the EBG structure and those emitted into space without reflection will mutually reinforce each other, even if the thickness is not λ / 4. This allows for a thinner antenna while maintaining radiation efficiency.

[0079] As described above, the first metasurface 21A and the second metasurface 21B are provided on the first low-loss film 20A and the second low-loss film 20B, respectively. In this case, a small antenna device can be realized by using a thin low-loss film.

[0080] use Figure 5 The equivalent circuit of the antenna device will be described. Figure 5 is the equivalent circuit diagram of the antenna device.

[0081] Inductance components L1 and L2 are generated between the first electrode 21A1 and the second electrode 21B1 and the first through hole 21A2 and the second through hole 21B2, respectively. In addition, capacitance components C1 and C2 are generated between the first electrode 21A1 and the second electrode 21B1 and the ground 29, respectively. Furthermore, capacitance components C1 and C2 are generated between the first electrode 21A1 and the second electrode 21B1 and the antenna pattern 17, respectively. g1 、C g2 .

[0082] As described above, by forming the first electrode 21A1 and the second electrode 21B1 on the thin multilayer first low-loss film 20A and the second low-loss film 20B, a filter can be constructed with a periodically continuous equivalent circuit (EBG structure) even with thin films. The filter is composed of inductors and capacitors.

[0083] By adjusting the filter characteristics composed of L and C, as well as the shape, size, number of repetitions, and thickness of multiple films of the electrode as the minimum unit of the periodic structure through simulation, broadband impedance matching can be achieved and the reflection coefficient Γ can be made +1.

[0084] In other words, the energy of the surface can be controlled using the concept of an equivalent circuit of a filter. Specifically, the multi-level structure of the metasurface placed on the human body side of antenna pattern 17 suppresses multiple reflections, reducing the energy transmitted from antenna pattern 17 to the human body. As a result, the reflection of radio waves from the human body can be reduced. As a result, the impact on antenna pattern 17 is reduced, allowing radio waves to be fully transmitted in the target direction.

[0085] It should be noted that the metasurface can be composed of holes arranged in a periodic two-dimensional square lattice (i.e., a matrix) in the conductive component. In addition, the shape of the conductive component or the hole is not particularly limited and can be various shapes as long as it can be periodically arranged.

[0086] use Figure 6 Modification examples of the top-view shape of the metasurface will be described. Figure 6 1 is a schematic top view showing the plane position of the metasurface in a modified example. The basic structure is the same as that of the aforementioned embodiment.

[0087] The third and fourth electrodes 21C1 and 21D1 correspond to the first and second electrodes 21A1 and 21B1 of the first embodiment and have a diamond shape. The third and fourth electrodes 21C1 and 21D1 are arranged alternately in rows and do not overlap when viewed from above. It should be noted that third through-holes 21C2 are provided for the third electrodes 21C1, and fourth through-holes 21D2 are provided for the fourth electrodes 21D1.

[0088] There are no particular restrictions on the shape and arrangement of the electrodes. For example, the electrodes may partially overlap.

[0089] 2. Second Implementation

[0090] In the first embodiment, the number of stacked low-loss films is three, but the number may be three or more.

[0091] use Figure 7 and Figure 8 A second embodiment as such an example will be described. Figure 7 It is a schematic diagram showing a cross-sectional structure of an antenna device according to a second embodiment. Figure 8 is a schematic top view showing the planar positions of antennas and metasurfaces in various low-loss films.

[0092] The antenna device 3 is, for example, a plate inverted F antenna (PIFA) and includes a metasurface layer 13 .

[0093] The supersurface layer 13 is composed of a plurality of low-loss films and a supersurface (described later). In the figure, an antenna pattern 17 is formed on the upper surface of the supersurface layer 13. The supersurface layer 13 and the antenna pattern 17 described above constitute an antenna film 19.

[0094] The antenna film 19 includes, from the lower side in the figure, a first low-loss film 20A, a second low-loss film 20B, a third low-loss film 20C, and a fourth low-loss film 20D. These films are stacked one on another.

[0095] The antenna pattern 17 is formed on the upper surface of the fourth low-loss film 20D.

[0096] A first electrode 21A1 of a first supersurface 21A is formed on the upper surface of the first low-loss film 20A, and a second electrode 21B1 of a second supersurface 21B is formed on the upper surface of the second low-loss film 20B.

[0097] A ground connection 29 is formed on the lower surface of the first low-loss film 20A.

[0098] The first electrodes 21A1 are arranged in a grid pattern with gaps between them, for example. The same applies to the second electrodes 21B1.

[0099] The first metasurface 21A has a first through-hole 21A2 connecting the first electrode 21A1 with the ground 29 .

[0100] The second metasurface 21B has a second through-hole 21B2 connecting the second electrode 21B1 with the ground 29 .

[0101] The first through holes 21A2 each correspond to one of the first electrodes 21A1 , pass through the second low-loss film 20B and the first low-loss film 20A, and connect the first electrode 21A1 to the ground 29 .

[0102] The same applies to the second through hole 21B2.

[0103] 3. Third Implementation

[0104] In the first embodiment, the number of stacked low-loss films is three, but the number may be three or more.

[0105] use Figure 9 and Figure 10 A third embodiment will be described as such an example. Figure 9 It is a schematic diagram showing a cross-sectional structure of an antenna device according to a third embodiment. Figure 10 is a schematic top view showing the planar positions of antennas and metasurfaces in various low-loss films.

[0106] exist Figure 9 The antenna device 3 is, for example, a planar inverted F antenna (PIFA) and has a metasurface layer 13 .

[0107] The supersurface layer 13 is composed of a plurality of low-loss films and a supersurface (described later). In the figure, an antenna pattern 17 is formed on the upper surface of the supersurface layer 13. The supersurface layer 13 and the antenna pattern 17 described above constitute an antenna film 19.

[0108] exist Figure 9 In FIG. 1 , the antenna film 19 includes, from the bottom of the figure, a first low-loss film 20A, a second low-loss film 20B, a third low-loss film 20C, a fourth low-loss film 20D, and a fifth low-loss film 20E. These films are stacked one on another.

[0109] The antenna pattern 17 is formed on the upper surface of the fifth low-loss film 20E.

[0110] The first electrode 21A1 of the first super surface 21A is formed on the upper surface of the second low-loss film 20B. The second electrode 21B1 of the second super surface 21B is formed on the upper surface of the third low-loss film 20C.

[0111] A ground connection 29 is formed on the upper surface of the first low-loss film 20A.

[0112] A third electrode 30 is formed on the lower surface of the first low-loss film 20A.

[0113] The first electrodes 21A1 are arranged in a grid pattern with gaps between them, for example. The same applies to the second electrodes 21B1.

[0114] The first metasurface 21A has a first through-hole 21A2 that connects the first electrode 21A1 , the ground 29 , and the third electrode 30 .

[0115] The second metasurface 21B has a second through-hole 21B2 connecting the second electrode 21B1 with the ground 29 .

[0116] The first through hole 21A2 corresponds to each of the first electrode 21A1 and the third electrode 30 , and penetrates the second low-loss film 20B and the first low-loss film 20A.

[0117] The same applies to the second through hole 21B2.

[0118] 4. Fourth embodiment

[0119] In the first to third embodiments, the number of stacked low-loss films having a metasurface formed thereon is two, but the number may be two or more.

[0120] use Figure 11 and Figure 12 A fourth embodiment will be described as such an example. Figure 11 It is a schematic diagram showing a cross-sectional structure of an antenna device according to a fourth embodiment. Figure 12 is a schematic top view showing the planar positions of antennas and metasurfaces in various low-loss films.

[0121] exist Figure 11 The antenna device 3 is, for example, a dipole antenna and has a metasurface layer 13 .

[0122] The supersurface layer 13 is composed of a plurality of low-loss films and a supersurface (described later). In the figure, an antenna pattern 17 is formed on the upper surface of the supersurface layer 13. The supersurface layer 13 and the antenna pattern 17 described above constitute an antenna film 19.

[0123] exist Figure 11 In FIG. 1 , the antenna film 19 includes, from the bottom of the figure, a first low-loss film 20A, a second low-loss film 20B, a third low-loss film 20C, and a fourth low-loss film 20D. These films are stacked one on another.

[0124] The antenna pattern 17 is formed on the upper surface of the fourth low-loss film 20D.

[0125] The first low-loss film 20A has a first electrode 21A1 of the first supersurface 21A formed on its upper surface. The second low-loss film 20B has a second electrode 21B1 of the second supersurface 21B formed on its upper surface. The third low-loss film 20C has a third electrode 21C1 of the third supersurface 21C formed on its upper surface.

[0126] A ground connection 29 is formed on the lower surface of the first low-loss film 20A.

[0127] The first electrodes 21A1 are arranged in a lattice pattern with gaps between them, and the same applies to the second electrodes 21B1 and the third electrodes 21C1.

[0128] The first metasurface 21A has a first through-hole 21A2 connecting the first electrode 21A1 with the ground 29 .

[0129] The second metasurface 21B has a second through-hole 21B2 connecting the second electrode 21B1 with the ground 29 .

[0130] The third metasurface 21C has a third through-hole 21C2 connecting the third electrode 21C1 with the ground 29 .

[0131] The first through holes 21A2 each correspond to one of the first electrodes 21A1 , penetrate the first low-loss film 20A, and connect the first electrode 21A1 to the ground 29 .

[0132] The same applies to the second through hole 21B2 and the third through hole 21C2.

[0133] 5. Fifth Implementation

[0134] In the first to fourth embodiments, the electrodes of the metasurface are connected to the ground through through-holes, but the through-holes of the electrodes can be omitted by increasing the area of the electrodes or shortening the intervals between layers.

[0135] use Figure 13 and Figure 14 A fifth embodiment will be described as such an example. Figure 13 It is a schematic diagram showing a cross-sectional structure of an antenna device according to a fifth embodiment. Figure 14 Schematic top view showing the planar positions of antennas and metasurfaces in various low-loss films.

[0136] The antenna device 3 is, for example, a plate inverted F antenna (PIFA) and includes a supersurface layer 13A.

[0137] The supersurface layer 13A is composed of a low-loss film and a supersurface (described later). In the figure, an antenna pattern 17A is formed on the upper surface of the supersurface layer 13A. The supersurface layer 13A and the antenna pattern 17A described above constitute an antenna film 19A.

[0138] The antenna film 19A includes a first low-loss film 22A, a second low-loss film 22B, and a third low-loss film 22C from the lower side of the figure. These films are stacked on each other.

[0139] The antenna pattern 17A is formed on the upper surface of the third low-loss film 22C.

[0140] The super surface electrode 13A1 is formed under the second low-loss film 22B. Figure 14As shown, the electrode 13A1 comprises a pair of electrodes extending side by side in one direction. Specifically, the pair of electrodes 13A1 have triangular protrusions extending toward each other, and there is no zigzag (sawtooth) electrode portion between the pair of electrodes.

[0141] A ground 29A is formed on the lower surface of the first low-loss film 22A. In summary, only the first low-loss film 22A is disposed between the electrode 13A1 of the metasurface and the ground 29A.

[0142] In this embodiment, no through-holes are formed to connect the electrodes to the ground. However, antenna performance is maintained by one or more of the following features, for example, the wide shape of the electrodes, the short distance between the electrodes and the ground, etc.

[0143] 6. Sixth Implementation

[0144] Another embodiment using a metasurface without through-holes will be described.

[0145] use Figures 15 to 17 A sixth embodiment as such an example will be described. Figure 15 It is a schematic diagram showing a cross-sectional structure of an antenna device according to a sixth embodiment. Figure 16 is a schematic top view showing the planar position of the metasurface. Figure 17 1 is a schematic top view showing a planar configuration of a ground.

[0146] exist Figure 15 The antenna device 3 has a metasurface layer 13 .

[0147] The supersurface layer 13 is composed of a plurality of low-loss films and a supersurface (described later). In the figure, an antenna pattern 17 is formed on the upper surface of the supersurface layer 13. The supersurface layer 13 and the antenna pattern 17 described above constitute an antenna film 19.

[0148] exist Figure 15 In FIG. 1 , the antenna film 19 includes a first low-loss film 20A and a second low-loss film 20B from the bottom of the figure. These films are stacked on each other.

[0149] The antenna pattern 17 is formed on the upper surface of the second low-loss film 20B.

[0150] The upper surface of the first low-loss film 20A is formed with a first super surface 21A. Figure 16 As shown, the first metasurface 21A is a complementary split ring resonator (CSRR) having a split ring-shaped cutout 31 .

[0151] A ground 29B is formed on the lower side of the first low-loss film 20A.

[0152] like Figure 17 As shown, the ground 29B is a defective ground structure (DGS) having a cutout 33 corresponding to the first metasurface 21A. The cutout 33 is H-shaped.

[0153] In summary, the antenna film 19 without a through hole is realized.

[0154] Furthermore, in summary, the metasurface is a single layer, but it can realize a multi-stage equivalent circuit similar to the first embodiment.

[0155] 7. Seventh Implementation

[0156] use Figure 18 and Figure 19 A seventh embodiment will be described. Figure 18 Schematic top view showing the planar positions of antennas and metasurfaces in each low-loss film in the seventh embodiment. Figure 19 Schematic top view of the metasurface in a modified example.

[0157] The layer structure of the seventh embodiment is the same as that of the fifth embodiment. That is, the metasurface is a single layer.

[0158] The antenna pattern 17A is linear and extends in one direction, and the antenna pattern 17A is fed with power at the center of the entire antenna pattern.

[0159] When viewed from above, the first electrode 21A1 of the first super surface 21A is H-shaped.

[0160] By achieving a small artificial magnetic conductor (AMC) as described above, the reflection coefficient Γ=+1 characteristic can maintain radiation efficiency and impedance matching, thereby minimizing the impact on the human body.

[0161] Figure 19 In the illustrated modification, the antenna pattern 17B is a coplanar waveguide (CPW) structure, and antenna power is supplied at the lower end of the CPW.

[0162] 8. Eighth Implementation

[0163] use Figure 20 An eighth embodiment will be described. Figure 20 is a schematic top view of the metasurface in the eighth embodiment.

[0164] In this embodiment, the electrode 41 of the metasurface 21 has a fractal shape. A fractal is a pattern in which a part of the pattern and the whole are self-similar (recursive).

[0165] Specifically, the electrode 41 of the metasurface 21 is formed of a plurality of self-similar quadrilaterals. It should be noted that the smallest unit of the electrode 41 is a quadrilateral conductive component, which has a quadrilateral portion in the middle where no conductive component is formed.

[0166] As mentioned above, the fractal shape of the metasurface electrodes facilitates broadband performance and miniaturization. In particular, the higher the fractal order, the more broadband characteristics can be achieved.

[0167] Previously, due to manufacturing issues, studies have been conducted to eliminate the through-holes in the metasurface. However, this approach has the problem of increasing the size of the metasurface and the overall area while maintaining the same performance.

[0168] When the electrodes on the metasurface are fractal-shaped, as in this embodiment, various equivalent circuits can be fabricated, thereby maintaining performance while miniaturizing the overall structure. This allows for the omission of through-holes. In this embodiment, the metasurface is a single layer, but it can also be multi-layered. In the case of multiple layers, through-holes can be present or omitted.

[0169] 9. Ninth Implementation

[0170] use Figure 21 A ninth embodiment will be described. Figure 21 This is a schematic top view of the super surface in the ninth embodiment.

[0171] In this embodiment, electrode 41A of metasurface 21 has a fractal shape. Specifically, electrode 41A is a shape composed of multiple self-similar quadrilaterals. Electrode 41A is an example of a fractal with a higher degree than electrode 41.

[0172] 10. Tenth Implementation

[0173] use Figure 22 A tenth embodiment will be described. Figure 22 4 is a schematic top view of the super surface in the tenth embodiment.

[0174] In this embodiment, the electrode 41B of the metasurface 21 has a fractal shape. Specifically, the electrode 41B is a pattern composed of countless self-similar triangles. It should be noted that the smallest unit of the electrode 41B is a triangular conductive component, and between three of these conductive components facing the same direction, there is a triangular portion in the opposite direction where no conductive component is formed.

[0175] 11. Eleventh Implementation Method

[0176] use Figure 23 and Figure 24 An eleventh embodiment will be described. Figure 23 This is a schematic perspective view of smart glasses incorporating the antenna device according to the eleventh embodiment. Figure 24 Schematic diagram showing the layer structure of the antenna device.

[0177] like Figure 23 As shown, the smart glasses 81 have an antenna device 83 built into them.

[0178] exist Figure 24 The lower side of the figure is the human body side. Antenna device 83 is, for example, Blutooth (registered trademark), and comprises, from the upper side to the lower side of the figure, a first cover layer 123, a ground plane 125, an insulating substrate 127, double-sided adhesive tape 129, an overcoat layer 113 (an example of an overcoat layer), and a second cover layer 131.

[0179] The supersurface layer 113 is composed of one or more low-loss films and a supersurface (described later). In the figure, an antenna pattern 117 is formed on the lower surface of the supersurface layer 113. The supersurface layer 113 is arranged on the human body side relative to the antenna pattern 117. The supersurface layer 113 and the antenna pattern 117 described above constitute the antenna film 119.

[0180] The configuration of the supersurface layer 113 is the same as that of the supersurface layers in the first to tenth embodiments.

[0181] 12. Twelfth Implementation

[0182] use Figures 25 to 29 A twelfth embodiment will be described. Figure 25 It is a schematic perspective view of a continuous blood glucose monitor incorporating an antenna device according to a twelfth embodiment. Figure 26 Schematic diagram showing a cross-sectional structure of an antenna device. Figure 27 is a schematic perspective view of an antenna device. Figure 28 is a schematic top view of the antenna device. Figure 29 is the equivalent circuit diagram of the antenna device.

[0183] The continuous glucose monitoring (GMC) 201 is worn on a person's wrist, and the measurement results are displayed on, for example, a display device (not shown).

[0184] like Figure 25 As shown, the GMC 201 has an antenna arrangement 203 .

[0185] The antenna device 203 is, for example, a dipole antenna. Figure 26 As shown, there is an antenna film 205. In the figure, the antenna film 205 includes, from bottom to top, a first low-loss film 207, a second low-loss film 209, and a third low-loss film 211. These films are stacked on top of each other.

[0186] Antenna film 205 includes a ground connection 221 formed on the lower surface of first low-loss film 207. Antenna film 205 includes a first conductor pattern 213 formed on the upper surface of first low-loss film 207. First conductor pattern 213 is circular in plan view. First through-holes 215 extend from first conductor pattern 213 to ground connection 221. First through-holes 215 provide a power supply for the antenna.

[0187] The antenna film 205 includes a second conductor pattern 217 formed on the upper surface of the second low-loss film 209. The second conductor pattern 217 is circular in plan view. The second conductor pattern 217 has a larger area than the first conductor pattern 213 and covers the first conductor pattern 213 in plan view.

[0188] A plurality of second vias 219 extend from the second conductor pattern 217 to the ground 221 . The second vias 219 are arranged around the first conductor pattern 213 .

[0189] A capacitance component C is generated between the first conductor pattern 213 and the second conductor pattern 217. L A capacitance component C is generated between the second conductor pattern 217 and the ground 221. R The inductance component L is generated in the second conductor pattern 217. R The inductance component L is generated in the second through hole 219. L .

[0190] In this embodiment, if Figure 27 and Figure 28 As shown, there are four second through holes 219 , which are equally spaced along the circumferential direction, that is, periodically arranged.

[0191] Through the above composition, such as Figure 29 As shown, an equivalent circuit that realizes the composite right- / left-handed transmission line (CRLH) characteristics is formed.

[0192] With the above configuration, due to the Zero Order Resonance (ZOR) characteristic, current flows through the second through-hole 219 even in the human body and its surrounding environment, allowing a large amount of current to flow throughout the dipole antenna. As a result, the antenna film 205 functions as a wideband antenna.

[0193] The number of the second through holes is not limited.

[0194] 13. Other Implementation Methods

[0195] While various embodiments of the present invention have been described above, the present invention is not limited to the aforementioned embodiments and various modifications are possible without departing from the spirit of the invention. In particular, the various embodiments and modifications described in this specification may be arbitrarily combined as needed.

[0196] Industrial Applicability

[0197] The present invention is widely applicable to antenna devices used near a human body or other conductors.

[0198] Description of Reference Numerals

[0199] 1…wireless earphones; 3…antenna device; 9…covering layer; 11…adhesive layer; 13…supersurface layer; 19…antenna film; 20A…first low-loss film; 20B…second low-loss film; 21A…first supersurface; 21A1…first electrode; 21A2…first through hole; 21B…second supersurface; 21B1…second electrode; 21B2…second through hole.

Claims

1. An antenna device for use in contact with or close to a human body or a conductor, the antenna device comprising: antennas; and The metasurface layer is a layer stacked on the antenna and arranged on the human body side, and comprises a low-loss film and a metasurface formed on the low-loss film. The low-loss film includes a first low-loss film and a second low-loss film stacked together. The metasurface includes a first metasurface and a second metasurface, a plurality of first electrodes of the first metasurface are formed on the upper surface of the first low-loss film, and a plurality of second electrodes of the second metasurface are formed on the upper surface of the second low-loss film. The first electrodes and the second electrodes are alternately arranged row by row and do not overlap with each other in a plan view.

2. The antenna device according to claim 1, wherein The low-loss film is stacked in multiple layers. The metasurface is formed on each of the plurality of low-loss films.

3. The antenna device according to claim 1 or 2, wherein: The low-loss film has a thickness of 150 μm or less.

4. The antenna device according to claim 1 or 2, wherein: The metasurface is a fractal shape.

5. The antenna device according to claim 3, wherein The metasurface is a fractal shape.

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