Noise removal body

Abstract

Provided is a noise removal body designed to reflect radio waves in a desired frequency band with minimal loss. A noise removal body 11 comprises first and second conductive layers 16 and 17 including a conductor 12, and a dielectric substrate layer 13 supporting the first and second conductive layers 16 and 17. In the noise removal body 11, the first conductive layer 16, the dielectric substrate layer 13, and the second conductive layer 17 are laminated in this order, and the noise removal body 11 specularly reflects radio waves. When the wavelength of the reflected radio waves is λ, the thickness of the dielectric substrate layer 13 is t, and the relative dielectric constant of the dielectric substrate layer 13 is ε, a substrate design coefficient Db = t ·√ε / λ is defined, and the substrate design coefficient Db is 0.0034 ≤ Db ≤ 0.12.

Description

Noise Eliminator

[0001] The present invention relates to a noise remover.

[0002] Communication devices such as mobile phones and wireless communication devices use radio waves in the frequency band of approximately 3 GHz to 300 GHz, known as centimeter waves or millimeter waves. Communication devices that use radio waves in such high-frequency bands can malfunction or suffer signal degradation due to interference with radio waves emitted by other electronic devices. For this reason, noise removers that absorb unwanted radio waves that cause noise are widely used.

[0003] As a noise remover, for example, a configuration in which a conductive substrate, a pressure-sensitive adhesive layer, and a release substrate are laminated in this order, and the conductive substrate includes a metal layer, is known (Patent Document 1).

[0004] Japanese Patent Application Laid-Open No. 2022-130302

[0005] It is known that the thicker the noise absorbing material that absorbs radio waves, the greater the radio wave absorbing effect. For this reason, most noise absorbing materials have been thick. However, due to space constraints at installation locations, noise absorbing materials that are as thin as possible are desired.

[0006] The present invention has been made in view of the above-mentioned problems, and has as its object to provide a noise remover that is as thin as possible and is designed to sufficiently remove radio waves that cause noise.

[0007] To achieve the above object, the present invention includes the following subject matter.

[0008] Item 1: A noise eliminator comprising first and second conductive layers each containing a conductor, and a dielectric substrate layer supporting the first and second conductive layers, and absorbing at least a portion of an incident radio wave, wherein the first conductive layer, the dielectric substrate layer, and the second conductive layer are laminated in this order, the noise eliminator specularly reflects the radio wave, and wherein a substrate design coefficient Db=t√ε / λ is defined as follows, where λ is the wavelength of the radio wave, t is the thickness of the dielectric substrate layer, and ε is the relative permittivity of the dielectric substrate layer, and the substrate design coefficient Db satisfies 0.0034≦Db≦0.12.

[0009] Item 2: A noise remover comprising first and second conductive layers each containing a conductor, and a dielectric substrate layer supporting the first and second conductive layers, and absorbing at least a portion of an incident radio wave, wherein the first conductive layer, the dielectric substrate layer, and the second conductive layer are laminated in this order, the noise remover specularly reflects the radio wave, and wherein, assuming that the wavelength of the radio wave is λ, the thickness of the dielectric substrate layer is t, and the dielectric substrate layer is a layer made of PET, a PET substrate design coefficient Dbp=t / λ is defined, and the PET substrate design coefficient Dbp satisfies 0.0017≦Dbp≦0.065.

[0010] Item 3: A noise eliminator comprising first and second conductive layers each containing a conductor, and a dielectric substrate layer supporting the first and second conductive layers, and absorbing at least a portion of incident radio waves, wherein the first conductive layer, the dielectric substrate layer, and the second conductive layer are laminated in this order, the noise eliminator specularly reflects radio waves, and wherein, assuming that the wavelength of the radio waves is λ, the thickness of the dielectric substrate layer is t, and the dielectric substrate layer is a layer made of FR4, an FR4 substrate design coefficient Dbf=t / λ is defined, and the FR4 substrate design coefficient Dbf satisfies 0.0017≦Dbf≦0.057.

[0011] Clause 4: A noise remover comprising first and second conductive layers each containing a conductor, and a dielectric substrate layer supporting the first and second conductive layers, and absorbing at least a part of an incident radio wave, wherein the first conductive layer, the dielectric substrate layer, and the second conductive layer are laminated in this order, the noise remover specularly reflects the radio wave, and wherein, assuming that the wavelength of the radio wave is λ, the thickness of the dielectric substrate layer is t, and the dielectric substrate layer is a layer made of glass, a glass substrate design coefficient Dbg is defined as Dbg=t / λ, and the glass substrate design coefficient Dbg satisfies 0.0014≦Dbg≦0.052.

[0012] Item 5: A noise remover comprising first and second conductive layers each containing a conductor, and a dielectric substrate layer supporting the first and second conductive layers, and absorbing at least a portion of incident radio waves, wherein the first conductive layer, the dielectric substrate layer, and the second conductive layer are laminated in this order, the noise remover specularly reflects radio waves, and wherein, assuming that the wavelength of the radio waves is λ, the thickness of the dielectric substrate layer is t, and the dielectric substrate layer is a layer made of silicon, a silicon substrate design coefficient Dbs=t / λ is defined, and the silicon substrate design coefficient Dbs satisfies 0.00091≦Dbs≦0.036.

[0013] Item 6: The noise remover according to any one of Items 1 to 5, wherein the first conductive layer includes a plurality of noise removal elements, and a difference between a phase of a radio wave incident on the noise removal elements and a phase of a radio wave reflected from the noise removal elements is the same.

[0014] Clause 7: A noise eliminator comprising first and second conductive layers each containing a conductor, and a dielectric substrate layer supporting the first and second conductive layers, and absorbing at least a portion of incident radio waves, wherein the first conductive layer, the dielectric substrate layer, and the second conductive layer are laminated in this order, and when reflecting radio waves, the noise eliminator reflects the radio waves at a reflection angle different from the angle of incidence, wherein: the wavelength of the radio waves is λ, the thickness of the dielectric substrate layer is t, and the relative dielectric constant of the dielectric substrate layer is ε, a substrate design coefficient Db=t√ε / λ is defined, and the substrate design coefficient Db satisfies 0.0034≦Db≦0.90.

[0015] Item 8: A noise remover comprising first and second conductive layers each containing a conductor, and a dielectric substrate layer supporting the first and second conductive layers, and absorbing at least a portion of an incident radio wave, wherein the first conductive layer, the dielectric substrate layer, and the second conductive layer are laminated in this order, and when reflecting a radio wave, the noise remover reflects the radio wave at a reflection angle different from the angle of incidence, wherein a PET substrate design coefficient Dbp is defined as Dbp=t / λ, where λ is the wavelength of the radio wave, t is the thickness of the dielectric substrate layer, and the dielectric substrate layer is a layer made of PET, and the PET substrate design coefficient Dbp satisfies 0.0017≦Dbp≦0.48.

[0016] Item 9: A noise filter comprising first and second conductive layers each containing a conductor, and a dielectric substrate layer supporting the first and second conductive layers, and absorbing at least a portion of incident radio waves, wherein the first conductive layer, the dielectric substrate layer, and the second conductive layer are laminated in this order, and when reflecting radio waves, the noise filter reflects the radio waves at a reflection angle different from the angle of incidence, wherein the wavelength of the radio waves is λ, the thickness of the dielectric substrate layer is t, and the dielectric substrate layer is a layer made of FR4, an FR4 substrate design coefficient Dbf is defined as Dbf=t / λ, and the FR4 substrate design coefficient Dbf satisfies 0.0017≦Dbf≦0.429.

[0017] Item 10: A noise remover comprising first and second conductive layers each containing a conductor, and a dielectric substrate layer supporting the first and second conductive layers, and absorbing at least a part of an incident radio wave, wherein the first conductive layer, the dielectric substrate layer, and the second conductive layer are laminated in this order, and when reflecting a radio wave, the noise remover reflects the radio wave at a reflection angle different from the angle of incidence, wherein a glass substrate design coefficient Dbg is defined as Dbg=t / λ, where λ is the wavelength of the radio wave, t is the thickness of the dielectric substrate layer, and the dielectric substrate layer is a layer made of glass, and the glass substrate design coefficient Dbg satisfies 0.0014≦Dbg≦0.39.

[0018] Item 11: A noise filter comprising first and second conductive layers each containing a conductor, and a dielectric substrate layer supporting the first and second conductive layers, and absorbing at least a portion of an incident radio wave, wherein the first conductive layer, the dielectric substrate layer, and the second conductive layer are laminated in this order, and when reflecting a radio wave, the noise filter reflects the radio wave at a reflection angle different from the angle of incidence, wherein the wavelength of the radio wave is λ, the thickness of the dielectric substrate layer is t, and the dielectric substrate layer is a layer made of silicon, a silicon substrate design coefficient Dbs=t / λ is defined, and the silicon substrate design coefficient Dbs satisfies 0.00091≦Dbs≦0.26.

[0019] Item 12: The noise remover according to any one of Items 7 to 11, wherein the first conductive layer includes a plurality of noise removal elements of two or more different types, and the different types of noise removal elements have different differences in phase between the radio waves incident on the different types of noise removal elements and the radio waves reflected from the different types of noise removal elements.

[0020] According to the present invention, it is possible to provide a noise remover that is designed to sufficiently remove radio waves that become noise while making the thickness as thin as possible.

[0021] Fig. 1 is a cross-sectional view of a portion of a noise removing body according to one embodiment of the present invention. Fig. 2 is a plan view of the noise removing body. Fig. 3 is a flowchart showing a method for designing a dielectric substrate layer. Fig. 4 is a cross-sectional view of a portion of a noise removing body according to another embodiment of the present invention. Fig. 5 is a plan view of the noise removing body. Fig. 6 is an explanatory diagram of the incident angle and reflection angle of radio waves incident on and reflected from the noise removing body. Fig. 7 is an explanatory diagram of incident waves and reflected waves of the noise removing body, where (A) is an explanatory diagram for the noise removing body of the embodiment shown in Fig. 1 and (B) is an explanatory diagram for the noise removing body of the embodiment shown in Fig. 4. Fig. 8 is a diagram explaining regular reflection and polarized reflection.

[0022] (First Embodiment) (Overall Configuration of Noise Remover 11) An embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a partial cross-sectional view of a noise remover 11 according to one embodiment of the present invention, and Fig. 2 is a partial plan view. The noise remover 11 of this embodiment absorbs at least a portion, and preferably most, of incident radio waves, but some of the radio waves are reflected without being absorbed by the noise remover 11.

[0023] The reflected wave is received by the receiving unit 101 and becomes noise. The radio wave generating source 100 is a communication device or the like having a transmitting antenna capable of transmitting radio waves. The receiving unit 101 is a device capable of receiving radio waves, such as a communication device having a receiving antenna. Examples of communication devices include smartphones, mobile phones, tablet devices, laptop computers, portable game consoles, repeaters, radios, and televisions.

[0024] In this specification, the incident angle α1 is the angle between the incident direction of the radio wave when it enters the noise removing body 11 (for example, as shown by arrow A1 in FIG. 6 ) and the direction in which the normal to the reflecting surface of the noise removing body 11 extends (for example, as shown by arrow A2 in FIG. 6 ). The reflection angle α2 is the angle between the reflection direction of the reflected wave (for example, as shown by arrow A3 in FIG. 6 ) and the normal to the reflecting surface. The normal refers to a straight line that is perpendicular to the tangent (or tangent plane) at the reflection point.

[0025] A portion of the incident wave is reflected by the noise remover 11 as a reflected wave at a reflection angle α2. Reflection at a reflection angle α2, which is the same as the incident angle α1, is called "specular reflection." The direction in which the specularly reflected reflected wave travels is called the "specular reflection direction." In the noise remover 11, which specularly reflects radio waves, the reflection intensity of the reflected wave in the specular reflection direction is greater than the reflection intensity of the reflected wave in other directions, i.e., the gain is maximum. For example, in the example of Figure 8, the reflection intensity of the reflected wave in the specular reflection direction is maximum, and a peak P3 appears in the reflection intensity of the reflected wave at the reflection angle α2. In other words, in specular reflection, there is no peak in the reflection intensity at the reflection angle α2, which is different from the incident angle α1.

[0026] Reflection of a reflected wave, including reflection at a reflection angle α2 different from the incident angle α1, is called "polarized reflection." In other words, there is at least one reflection angle α2 at which the reflection intensity of the reflected wave is greater than that of other reflection angles α2, and the reflection angle α2 of the reflected wave at this point is an angle different from the incident angle α1. The reflection angle α2 is designed to be a desired angle. The direction in which the reflected wave that is polarized and reflected at the desired reflection angle α2 travels is called the "polarized reflection direction." In a noise remover 11 that exhibits polarized reflection, the reflection intensity of the reflected wave in the polarized reflection direction is greater than that of the reflected wave in other directions within a certain range of reflection angles α2. For example, in the example of FIG. 8 , there is a peak P1 of reflection intensity where the reflection intensity of the reflected wave in the polarized reflection direction is greater than that of the reflected wave in other directions. Furthermore, there may be another peak P2 of reflection intensity in a direction different from the polarized reflection direction (e.g., a direction at the same angle as the incident angle α1), and the peak P1 of reflection intensity in the polarized reflection direction does not necessarily have to be the maximum reflection intensity.

[0027] In the example of Fig. 6, the incident angle α1 of the incident wave is 60 degrees. In the case of specular reflection, the reflected wave is reflected at a reflection angle α2 that is the same as the incident angle α1, i.e., in Fig. 6, in the direction of arrow A3 where the reflection angle α2 is 60 degrees. In the case of polarized reflection, the reflected wave is reflected at a desired reflection angle α2 that is different from the incident angle α1, i.e., in Fig. 6, in the direction of arrow A2 where the desired reflection angle α2 is 0 degrees.

[0028] The noise remover 11 of the present invention absorbs incident radio waves and specularly reflects a part of the incident radio waves.

[0029] The shape of the noise removing body 11 in a planar view is not limited, but is preferably, for example, a square with a side length of 20 cm or more and 400 cm or less. Radio waves with frequencies of 3 GHz or more and 300 GHz or less attenuate with distance, but in order to reflect the waves with sufficient intensity at all points within a practical distance from the radio wave source, the side length is preferably 20 cm or more. The upper limit of the side length is not particularly limited, but from a manufacturing perspective, 400 cm or less is preferable. The overall shape of the noise removing body 11 is not limited to a square and may be a rectangle or a polygon such as a triangle, pentagon, or hexagon. In this case, the length of the shortest side is set to 20 cm or more and 400 cm or less. Alternatively, the shortest distance between a vertex and the opposite side, or the shortest distance between a side and the opposite side, may be set to 20 cm or more and 400 cm or less. Furthermore, if the overall shape of the noise removing body 11 is circular, the diameter is set to 20 cm or more and 400 cm or less. When the overall shape of the noise removing body 11 is elliptical, the minor axis is set to 20 cm or more and 400 cm or less. When the overall shape of the noise removing body 11 is fan-shaped, the length of the shorter arc or radius is set to 20 cm or more and 400 cm or less. Furthermore, the overall shape of the noise removing body 11 may be three-dimensional, such as cylindrical or conical. The shape and size of the noise removing body 11 are appropriately selected depending on the manner in which the noise removing body 11 is used.

[0030] The noise eliminating body 11 preferably has a thickness L1 of 1 mm or less. The thickness L1 of the noise eliminating body 11 is set to a thickness that allows the noise eliminating body 11 to have flexibility and prevents force from being concentrated on the conductor 12 when an external force is applied to the noise eliminating body 11 to bend it.

[0031] (Structure of Noise Eliminator 11) The noise eliminater 11 includes a first conductive layer 16 including a conductor 12, a dielectric substrate layer 13 supporting the first conductive layer 16, and a second conductive layer 17 including a conductor, provided on the surface of the dielectric substrate layer 13 opposite to the surface on which the first conductive layer 16 is provided. In the embodiment shown in FIG. 1 , the first conductive layer 16, the dielectric substrate layer 13, and the second conductive layer 17 are laminated in this order. Radio waves are incident on the first conductive layer 16 side and are reflected. Although not shown, a protective layer for protecting the first conductive layer 16 may be provided on the surface of the first conductive layer 16 opposite to the dielectric substrate layer 13 (upper side in FIG. 1 ) and on the surface of the second conductive layer 17 opposite to the dielectric substrate layer 13 (lower side in FIG. 1 ). Furthermore, an adhesive layer made of an adhesive may be provided between the protective layer and the first conductive layer 16 and the second conductive layer 17 to bond the protective layer to the first conductive layer 16 and the second conductive layer 17.

[0032] (First conductive layer 16) The first conductive layer 16 includes a plurality of noise elimination elements 20 having the same shape in a planar view. Each noise elimination element 20 includes a thin-film conductor 12 formed in a predetermined shape in a planar view on the upper surface of the dielectric substrate layer 13. The first conductive layer 16 is formed by periodically arranging the noise elimination elements 20 on the dielectric substrate layer 13, which is formed in a sheet shape, with each noise elimination element 20 serving as a unit.

[0033] The difference between the phase of the radio wave incident on the noise removal element 20 and the phase of the radio wave reflected from each noise removal element 20 (hereinafter also referred to as "phase difference" or "phase difference of the noise removal element") is determined according to the shape, etc. of the noise removal element 20. In this embodiment, since each noise removal element 20 has the same shape, the phase difference among the multiple noise removal elements 20 is the same.

[0034] The radio waves incident on (or reflected from) the noise removal element 20 refer to the radio waves incident on (or reflected from) the area where the noise removal element 20 is formed in a planar view in the noise removal body 11 of this embodiment.

[0035] As a result, the noise eliminating body 11 specularly reflects the incident wave incident at an incident angle α1. For the sake of explanation, only one noise eliminating element 20 constituting one unit is shown in Figures 1 and 2. The conductors 12 of adjacent noise eliminating elements 20 may be one continuous unit.

[0036] An example of the noise elimination element 20 is shown in Fig. 2. In the example of Fig. 2, the noise elimination element 20 has a square shape in a plan view, and is made up of a conductor 12 and a region 12a surrounded by the conductor 12 where no conductor is present.

[0037] The configuration of the noise elimination element 20 is not limited to the example shown in Fig. 2 and may be appropriately selected depending on the frequency and intensity of the radio waves to be absorbed. For example, the planar shape may be any shape such as a rectangle, a circle, an ellipse, a triangle, or a polygon.

[0038] The shape, size, and arrangement of the conductors 12 and the regions 12a without conductors 12 may be arbitrary. For example, conductors 12 of any shape, such as rectangular, circular, elliptical, triangular, or polygonal, and regions 12a without conductors 12 between the conductors 12 may be periodically arranged. Furthermore, for example, multiple linear conductors 12 may be arranged vertically and horizontally in a lattice pattern, or may be arranged to form a rectangular, circular, elliptical, triangular, polygonal, or other contour. In this case, the linear conductors 12 surround regions 12a without conductors 12 of any shape, such as square, rectangular, circular, elliptical, triangular, or polygonal. The term "linear" means that the longitudinal length is 3000 times or more the length in the direction perpendicular to the longitudinal direction.

[0039] Furthermore, the thickness L3 of the first conductive layer 16, i.e., the thickness (film thickness) L3 of the noise elimination element 20, is preferably thick enough to transmit visible light. The thickness L3 of the noise elimination element 20 is preferably 0.05 μm or more and 10 μm or less. From the viewpoint of ensuring appropriate radio wave intensity, the thickness L3 is preferably 5 nm or more.

[0040] Furthermore, the multiple noise elimination elements 20 on the first conductive layer 16 are not limited to being identical. As long as the difference between the phase of the radio wave incident on each noise elimination element 20 and the phase of the radio wave reflected from each noise elimination element 20 is the same, the configuration of each noise elimination element 20 may be different, and for example, the material, thickness, shape, size, etc. of the conductor 12 of each noise elimination element 20 may be different.

[0041] The conductor 12 is preferably made of, for example, silver. However, the conductor 12 of the first conductive layer 16 may be made of any metal, metal compound, or alloy having free electrons, and is not limited to silver. For example, gold, copper, platinum, aluminum, titanium, silicone, indium tin oxide, and alloys (e.g., alloys containing nickel, chromium, and molybdenum) may also be used. Examples of alloys containing nickel, chromium, and molybdenum include various grades of Hastelloy B-2, B-3, C-4, C-2000, C-22, C-276, G-30, N, W, and X.

[0042] One example of a method for manufacturing the first conductive layer 16 is to form a conductive film, then form a pattern by etching, and then extract a conductive thin film having the pattern. Another example is to apply a photosensitive resist to a base film provided with a lift-off layer, form a pattern by photolithography, fill the patterned portion with conductor 12, and then extract the conductive thin film having the pattern. Note that the manufacturing method is not limited to the above, and examples of methods for forming the first conductive layer 16 include a method of adhering a metal thin film and a method of vapor-depositing a metal.

[0043] (Dielectric substrate layer 13) The dielectric substrate layer 13 is a sheet-like member on whose upper surface the first conductive layer 16 is formed. The term "sheet" refers to a shape in which the thickness of the object is 10% or less of the maximum length between the outer edges in a planar view. When the shape in a planar view is rectangular, the "maximum length between the outer edges in a planar view" refers to the length of the diagonal. When the shape in a planar view is circular, the "maximum length between the outer edges in a planar view" refers to the length of the diameter. In this specification, the term "sheet" also includes membranes, foils, films, etc.

[0044] The dielectric substrate layer 13 is made of materials such as PET (polyethylene terephthalate), FR4 (glass fiber cloth impregnated with epoxy resin and heat-cured to form a plate), glass, silicon, etc. Alternatively, synthetic resins may be used, examples of which include one or more selected from the group consisting of polyethylene, polypropylene, polyvinyl chloride, polystyrene, polymethyl methacrylate, polyester, polyformaldehyde, polyamide, polyphenylene ether, vinylidene chloride, polyvinyl acetate, polyvinyl acetal, AS resin, ABS resin, acrylic resin, fluororesin, nylon resin, polyacetal resin, polycarbonate resin, polyamide resin, and polyurethane resin.

[0045] The dielectric substrate layer 13 has an outer shape that is square in plan view, but is not limited to this and may have a rectangular, circular, elliptical, sector-shaped, polygonal, three-dimensional, or other shape that matches the overall shape of the noise remover 11.

[0046] (Second Conductive Layer 17) The second conductive layer 17 is composed of a single thin film conductor having a size corresponding to the dielectric substrate layer 13, and the conductor is, for example, a thin film of a metal such as aluminum or copper. The second conductive layer 17 reflects radio waves that have passed through the first conductive layer 16 and the dielectric substrate layer 13. The second conductive layer 17 is fabricated on the surface of the dielectric substrate layer 13 opposite to the surface on which the first conductive layer 16 is provided, using the same fabrication method as the first conductive layer. The thickness L11 is preferably 0.05 μm or more and 10 μm or less. From the viewpoint of ensuring appropriate radio wave intensity, the thickness L11 is preferably 0.5 nm or more.

[0047] The second conductive layer 17 is not limited to the above configuration, and may be made of a metal plate having a size corresponding to that of the dielectric substrate layer 13 .

[0048] (Substrate Design Coefficient) When the wavelength of the incident radio wave that is absorbed or reflected is λ (mm), the thickness of the dielectric substrate layer 13 is t (mm), and the relative dielectric constant of the dielectric substrate layer 13 is ε, the substrate design coefficient Db is defined as Equation 1-1: Db=t·√ε / λ (Equation 1-1), where √ε represents the square root of ε. In this case, the noise remover 11 has a substrate design coefficient Db that satisfies the following: 0.0034≦Db≦0.12 (Equation 1-2).

[0049] The method for designing the dielectric substrate layer 13 of the noise filter 11 is shown in the flowchart of FIG. 3 . First, a step of determining the wavelength λ is performed (Step S1). Since the wavelength λ is determined by the frequency of the radio waves, the frequency of the desired radio waves to be absorbed by the noise filter 11 is determined. This determined frequency is also referred to as the "corresponding frequency f." Next, a step of determining the material of the dielectric substrate layer 13 is performed (Step S2). This determines the relative permittivity ε. Then, a step of determining the thickness t of the dielectric substrate layer 13 is performed (Step S3). The thickness t of the dielectric substrate layer 13 is set within a range in which the substrate design coefficient Db satisfies Equation 1-2. Typically, a thinner noise filter 11 makes it easier to handle the noise filter 11 during installation, so the thickness t of the dielectric substrate layer 13 is set as thin as possible. The shape and size of the noise filter 11 in a plan view are arbitrary.

[0050] The steps of determining the wavelength λ, determining the material of the dielectric substrate layer 13, and determining the thickness t of the dielectric substrate layer 13 may be performed in any order. For example, depending on the installation location of the noise eliminating body 11, it may be difficult to install the noise eliminating body 11 if the thickness L1 of the noise eliminating body 11 is large. In such a case, in order to make the dielectric substrate layer 13 as thin as possible, the step of determining the thickness t of the dielectric substrate layer 13 may be performed first, then the wavelength λ may be determined, and finally a material for the dielectric substrate layer 13 having a relative dielectric constant ε that satisfies Expression 1-2 may be determined.

[0051] In order for the noise remover 11 to have a sufficient noise removal effect, the substrate design coefficient Db is preferably 0.0095 or more and 0.12 or less, and more preferably 0.0095 or more and 0.057 or less.

[0052] As described above, PET, FR4, glass, and silicon are preferably used as the material for the dielectric substrate layer 13. Since the relative dielectric constants ε of PET, FR4, glass, and silicon are 3.6, 4.4, 5.5, and 11.9, respectively, the relative dielectric constant ε is determined once the material of the dielectric substrate layer 13 in Equation 1-1 is determined.

[0053] When the material of the dielectric substrate layer 13 is PET, the substrate design coefficient is particularly defined as a PET substrate design coefficient Dbp, and Equation 2-1 is defined as follows: PET substrate design coefficient Dbp=Db / √ε=t / λ (Equation 2-1) In this case, the PET substrate design coefficient Dbp of the noise remover 11 satisfies the following: 0.0017≦Dbp≦0.065 (Equation 2-2)

[0054] When the material of the dielectric substrate layer 13 is FR4, the substrate design coefficient is particularly defined as an FR4 substrate design coefficient Dbf, and Equation 3-1 is defined as follows: FR4 substrate design coefficient Dbf=Db / √ε=t / λ (Equation 3-1) In this case, the FR4 substrate design coefficient Dbf of the noise remover 11 satisfies the following: 0.0017≦Dbf≦0.057 (Equation 3-2)

[0055] When the material of the dielectric substrate layer 13 is glass, the substrate design coefficient is particularly defined as a glass substrate design coefficient Dbg, and Equation 4-1 is defined as follows: Glass substrate design coefficient Dbg=Db / √ε=t / λ (Equation 4-1) In this case, the noise remover 11 has a glass substrate design coefficient Dbg that satisfies the following: 0.0014≦Dbg≦0.052 (Equation 4-2)

[0056] When the material of the dielectric substrate layer 13 is silicon, the substrate design coefficient is particularly defined as a silicon substrate design coefficient Dbs, and Equation 5-1 is defined as follows: Silicon substrate design coefficient Dbs=Db / √ε=t / λ (Equation 5-1) In this case, the silicon substrate design coefficient Dbs of the noise remover 11 satisfies the following: 0.00091≦Dbs≦0.036 (Equation 5-2)

[0057] (Operation of noise remover 11) The noise remover 11 of this embodiment absorbs radio waves incident as noise, thereby suppressing the adverse effects of the noise on electronic devices and the like arranged in the vicinity. By designing the substrate design coefficient Db shown in Equation 1-1 to be within the range of Equation 1-2, the noise remover 11 can sufficiently absorb radio waves of the corresponding frequency f while making the thickness t as small as possible.

[0058] Furthermore, a portion of the radio waves incident on the noise remover 11 as noise is reflected without being absorbed by the noise remover 11. At this time, the reflected waves in the specular reflection direction become even more noise, so it is necessary to reduce the intensity of the reflected waves in the specular reflection direction as much as possible. The noise remover 11 of this embodiment has a large absorption effect, so it is possible to reduce the reflection intensity of the reflected waves in the specular reflection direction, i.e., to further reduce noise.

[0059] In the example shown in Fig. 7(A), radio waves are incident in a direction perpendicular to the plane of the noise removing body 11, i.e., at an incident angle α1 of 0 degrees. Most of the waves are absorbed by the noise removing body 11, but a portion is specularly reflected by the noise removing body 11 at a reflection angle α2 of 0 degrees, i.e., in the same perpendicular direction as the incident wave, relative to the plane of the noise removing body 11. However, because the noise removing body 11 of this embodiment has a high absorption effect, the reflection intensity of the reflected wave reflected in the perpendicular direction is small. Note that Fig. 7(A) and Fig. 7(B), which will be described later, are diagrams for explaining incident and reflected radio wave waves, and the arrows in the figures do not indicate the actual intensities or propagation directions of the incident and reflected waves.

[0060] Furthermore, by setting the substrate design coefficients Dbp, Dbf, Dbg, and Dbs of each material within the ranges of Equations 2-2 to 5-2 according to the material of the dielectric substrate layer 13, it is possible to obtain a noise remover 11 that has the smallest possible thickness t and that sufficiently absorbs radio waves of the corresponding frequency f.

[0061] In the noise remover 11 of this embodiment, radio waves are incident from the first conductive layer 16 side, pass through the dielectric substrate layer 13, and reach the second conductive layer 17. At this time, the phases of the incident and reflected waves of the radio waves that reach the second conductive layer 17 and the radio wave absorption rate are determined depending on the thickness t of the dielectric substrate layer 13, i.e., the propagation distance of the radio waves and the relative dielectric constant ε of the dielectric substrate layer 13. In this way, the phases of the incident and reflected waves of the radio waves change depending on the setting of the substrate design coefficient Db, which includes the thickness t and the relative dielectric constant ε, and the direction of specular reflection of the radio waves and the radio wave absorption rate of the noise remover 11 change. The radio wave absorption rate is the ratio of the intensity of the absorbed radio waves to the incident intensity of the incident wave, and is calculated by the equation: absorption rate = (incident intensity RI - reflected intensity RO - transmitted intensity RT) / incident intensity RI x 100.

[0062] The direction in which the radio waves are specularly reflected and the radio wave absorption rate of the noise remover 11 of this embodiment are determined as appropriate by setting the different types of noise removing elements 20A to 20C, the substrate design coefficient Db, the PET substrate design coefficient Dbp, etc. Note that the "PET substrate design coefficient Dbp, etc." refers to the PET substrate design coefficient Dbp, the FR4 substrate design coefficient Dbf, the glass substrate design coefficient Dbg, and the silicon substrate design coefficient Dbs.

[0063] (Other Embodiments) (Overall Configuration of Noise Eliminator 11) Another embodiment will be described with reference to the drawings. Fig. 4 is a partial cross-sectional view of a noise eliminater 11 according to another embodiment, and Fig. 5 is a partial plan view of a noise eliminater 11 according to another embodiment.

[0064] The noise remover 11 of this embodiment polarizes and reflects the reflected wave. In this embodiment, the configuration of the first conductive layer 16 is different from that of the embodiment shown in Fig. 1, and this configuration polarizes and reflects the reflected wave. In the description of this embodiment, the same components as those in the embodiment shown in Fig. 1 are denoted by the same reference numerals, and description thereof will be omitted.

[0065] (First conductive layer 16) The first conductive layer 16 includes a plurality of different types of noise elimination elements 20A to 20C. Each of the noise elimination elements 20A to 20C includes a thin-film conductor 12 formed in a predetermined shape in plan view on the upper surface of the dielectric substrate layer 13. The first conductive layer 16 is formed by periodically arranging these plurality of types of noise elimination elements 20A to 20C as one unit on the dielectric substrate layer 13, which is formed in a sheet shape.

[0066] The different types of noise elimination elements 20A to 20C refer to noise elimination elements 20A to 20C that are designed so that the difference between the phase of an incident radio wave and the phase of a radio wave reflected from each noise elimination element (hereinafter also referred to as "phase difference") is different for each type. In the example shown in Figures 4 and 5, the first conductive layer 16 includes three types of noise elimination elements 20A to 20C.

[0067] As a result, the noise eliminating body 11 polarizes and reflects the incident wave incident at an incident angle α1. For the sake of explanation, only three types of noise eliminating elements 20A to 20C that constitute one unit are shown in Figures 4 and 5. The two-dot chain lines in Figures 4 and 5 indicate the boundaries between the noise eliminating elements 20A to 20C. The conductors 12 of adjacent noise eliminating elements 20A to 20C may be continuous and integral.

[0068] 5, each of the noise elimination elements 20A to 20C is made up of a conductor 12 and a region 12a without the conductor 12 that is surrounded by the conductor 12. When viewed from above, the shapes of the conductor 12 and the region 12a without the conductor 12 differ from each other in each of the noise elimination elements 20A to 20C.

[0069] The configuration of the multiple noise elimination elements 20A to 20C on the first conductive layer 16 is not limited to the example in Fig. 5, and any configuration may be used as long as it can differentiate the phases of the reflected waves from each of the noise elimination elements 20A to 20C. For example, the material, thickness, shape, and size of the conductors 12 constituting each noise elimination element 20, and the shape and size of the regions 12a without the conductors 12, may be varied to differentiate the phase differences of the reflected waves from different types of noise elimination elements 20A to 20C.

[0070] Each unit of the noise elimination elements 20A to 20C may include two or more types of noise elimination elements 20A to 20C, and may include, for example, a plurality of the same type of noise elimination elements 20A to 20C. Also, each unit of the noise elimination elements 20A to 20C may be of a plurality of types, and each unit may include different types of noise elimination elements 20A to 20C.

[0071] The other configurations are the same as those of the noise elimination element 20 described in the embodiment of FIG. 1, and therefore the description thereof will be omitted.

[0072] (Substrate Design Coefficient) When the wavelength of the incident and absorbed or reflected radio wave is λ (mm), the thickness of the dielectric substrate layer 13 is t (mm), and the relative dielectric constant of the dielectric substrate layer 13 is ε, the substrate design coefficient Db is defined as Equation 6-1: Db=t·√ε / λ (Equation 6-1), where √ε represents the square root of ε. In this case, the noise remover 11 has a substrate design coefficient Db that satisfies the following: 0.0034≦Db≦0.90 (Equation 6-2).

[0073] In order for the noise remover 11 to have a sufficient radio wave absorbing effect, the substrate design coefficient Db is preferably 0.019 or more and 0.19 or less, and more preferably 0.019 or more and 0.15 or less.

[0074] In this way, by designing the noise removing body 11 so that the substrate design coefficient Db shown in Equation 6-1 falls within the range of Equation 6-2, it is possible to easily design the noise removing body 11 so that it sufficiently absorbs radio waves of the corresponding frequency f. At this time, it is assumed that the reflection angle α2 of the reflected wave from the noise removing body 11 is designed to be a desired angle.

[0075] PET, FR4, glass, and silicon are preferably used as the material for the dielectric substrate layer 13. Since the relative dielectric constants ε of PET, FR4, glass, and silicon are 3.6, 4.4, 5.5, and 11 to 9, respectively, the relative dielectric constant ε is determined once the material of the dielectric substrate layer 13 is determined in Equation 6-1.

[0076] When the material of the dielectric substrate layer 13 is PET, the substrate design coefficient is particularly defined as a PET substrate design coefficient Dbp, and Equation 7-1 is defined as follows: PET substrate design coefficient Dbp=Db / √ε=t / λ (Equation 7-1) In this case, the PET substrate design coefficient Dbp of the noise remover 11 satisfies the following: 0.0017≦Dbp≦0.48 (Equation 7-2)

[0077] When the material of the dielectric substrate layer 13 is FR4, the substrate design coefficient is particularly defined as an FR4 substrate design coefficient Dbf, and Equation 8-1 is defined as follows: FR4 substrate design coefficient Dbf=Db / √ε=t / λ (Equation 8-1) In this case, the FR4 substrate design coefficient Dbf of the noise remover 11 satisfies the following: 0.0017≦Dbf≦0.429 (Equation 8-2)

[0078] When the material of the dielectric substrate layer 13 is glass, the substrate design coefficient is particularly defined as a glass substrate design coefficient Dbg, and Equation 9-1 is defined as follows: Glass substrate design coefficient Dbg=Db / √ε=t / λ (Equation 9-1) In this case, the noise remover 11 has a glass substrate design coefficient Dbg that satisfies the following: 0.0014≦Dbg≦0.39 (Equation 9-2)

[0079] When the material of the dielectric substrate layer 13 is silicon, the substrate design coefficient is particularly defined as a silicon substrate design coefficient Dbs, and Equation 10-1 is defined as follows: Silicon substrate design coefficient Dbs=Db / √ε=t / λ (Equation 10-1) In this case, the silicon substrate design coefficient Dbs of the noise remover 11 satisfies the following: 0.00091≦Dbs≦0.26 (Equation 10-2)

[0080] (Operation of noise remover 11) The noise remover 11 of this embodiment absorbs radio waves incident as noise, thereby suppressing the adverse effects of the noise on electronic devices and the like arranged in the vicinity. By designing the noise remover 11 so that the substrate design coefficient Db shown in Equation 6-1 falls within the range of Equation 6-2, the thickness t of the noise remover 11 can be made as small as possible, and radio waves of the corresponding frequency f can be sufficiently absorbed.

[0081] As described above, when radio waves are incident on the noise removing body 11 at an incident angle α1, part of the radio waves is absorbed by the noise removing body 11, and part is reflected by the noise removing body 11. In this case, the reflected waves reflected in the direction of a reflection angle α2 that is the same as the incident angle α1 become further noise, so the intensity of these reflected waves needs to be reduced. In the case of the noise removing body 11 that polarizes and reflects radio waves as in this embodiment, the radio waves are reflected in the direction of a reflection angle α2 that is the same as the incident angle α1, and may also be polarized and reflected in the direction of a desired reflection angle α2. Since the reflected waves are dispersed in the direction of a reflection angle α that is the same as the incident angle α1 and in the polarized reflection direction, the reflection intensity of the reflected waves reflected at a reflection angle α2 that is the same as the incident angle α1 is reduced, thereby reducing noise.

[0082] 7(B), when a radio wave is incident in a direction perpendicular to the plane of the noise removing body 11, i.e., at an incident angle α1 of 0 degrees, part of the incident wave is absorbed by the noise removing body 11 and part is reflected by the noise removing body 11. The reflected wave at this time is polarized and reflected in a predetermined desired polarized reflection direction, and the reflection intensity of the reflected wave reflected at a reflection angle α2 of 0 degrees is small, thereby reducing noise.

[0083] Furthermore, by setting the substrate design coefficients Dbp, Dbf, Dbg, and Dbs of each material within the ranges of Equations 7-2 to 10-2 according to the material of the dielectric substrate layer 13, it is possible to obtain a noise remover 11 that has the smallest possible thickness t and that sufficiently absorbs radio waves of the corresponding frequency f.

[0084] In the noise remover 11 of this embodiment, radio waves are incident from the first conductive layer 16 side, pass through the dielectric substrate layer 13, and reach the second conductive layer 17. At this time, the phases of the incident and reflected waves of the radio waves that reach the second conductive layer 17 and the radio wave absorption rate are determined depending on the thickness t of the dielectric substrate layer 13, i.e., the propagation distance of the radio waves and the relative dielectric constant ε of the dielectric substrate layer 13. In this way, the phases of the incident and reflected waves of the radio waves change depending on the setting of the substrate design coefficient Db, which includes the thickness t and the relative dielectric constant ε, and so the direction of polarized reflection of the radio waves and the radio wave absorption rate of the noise remover 11 change.

[0085] The direction in which the radio waves are polarized and reflected by the noise remover 11 of this embodiment and the radio wave absorption rate are determined appropriately by setting the different types of noise removing elements 20A to 20C, the substrate design coefficient Db, the PET substrate design coefficient Dbp, etc.

[0086] (Evaluation Test) Examples 1 to 30 were prepared as the noise remover 11, and an evaluation test was conducted on the radio wave reflection characteristics of Examples 1 to 30 and Comparative Examples 1 to 27. However, the noise remover 11 of the present invention is not limited to Examples 1 to 30.

[0087] (Explanation of Examples and Comparative Examples) (Overall Configuration) The noise eliminating bodies 11 produced in Examples 1 to 30 and Comparative Examples 1 to 27 are each formed by laminating a second conductive layer 17, a dielectric substrate layer 13, and a first conductive layer 16 in this order. The noise eliminating body 11 is a square with one side measuring 360 mm in plan view. The configuration of each layer in Examples 1 to 30 and Comparative Examples 1 to 27 will be described below.

[0088] (Configuration of First Conductive Layer 16) The first conductive layer 16 in Examples 1 to 30 and Comparative Examples 1 to 27 has the configuration of either Pattern A or Pattern B described below. Tables 1, 2, 4, and 5 show the patterns of Examples 1 to 30 and Comparative Examples 1 to 27. In the following description of Patterns A and B, the direction along one side of the square-shaped noise elimination elements 20, 20A to 20C in plan view is defined as the up-down direction, and the direction perpendicular to the up-down direction is defined as the left-right direction, and these up-down, left-right directions correspond to the up-down, left-right directions in FIGS.

[0089] (Pattern A) The first conductive layer 16 is provided with the same noise eliminating elements 20 as shown in FIG. 2. FIG. 2 is a plan view of the noise eliminating body 11 of pattern A created for this evaluation test. The noise eliminating elements 20 are square regions with a side length L20 of 1.3 mm in plan view. The first conductive layer 16 is formed by arranging a plurality of noise eliminating elements 20 on the dielectric substrate layer 13, with the noise eliminating element 20 shown in FIG. 2 being one unit. No gap is provided between adjacent noise eliminating elements 20.

[0090] The noise elimination element 20 comprises a thin-film conductor 12 having a thickness L3 of 2 μm formed on the upper surface of the dielectric substrate layer 13, and a conductor-free region 12a surrounded by the conductor 12. The conductor 12 comprises top, bottom, left, and right side edge portions 21a-21d extending along the four edges of the square, and a central portion 22 located at the center in the vertical direction in FIG. 2 and extending from the right side edge portion 21a to the left. The central portion 22 extends in the horizontal direction to approximately half the length L20 of one side, and comprises a first central portion 22a whose vertical length is approximately 5 / 6 of the length L20. The central portion 22 further comprises a second central portion 22b continuing from the first central portion 22a to the left, whose vertical length is approximately 1 / 8 of the length L20 of one side, and whose horizontal length is approximately 1 / 10 of the length L20 of one side. The region 12a without the conductor 12 is a region surrounded by the upper, lower, left, and right side edge portions 21a to 21d, the first central portion 22a, and the second central portion 22b. The dielectric substrate layer 13 is exposed through the region 12a without the conductor 12.

[0091] (Pattern B) The first conductive layer 16 is provided with different types of noise elimination elements 20. FIG. 5 is a plan view of the noise elimination body 11 of pattern B created for this evaluation test, which is provided with three types of noise elimination elements 20A to 20C. Each of the noise elimination elements 20A to 20C is square in shape with a side length L20 of 13 mm in plan view. The first conductive layer 16 is formed by arranging these noise elimination elements 20A to 20C arranged in a row as one unit on the dielectric substrate layer 13. Adjacent units of noise elimination elements 20 are arranged without any gaps between them.

[0092] Each of the noise elimination elements 20A to 20C comprises a thin-film conductor 12 having a thickness L3 of 2 μm formed on the upper surface of the dielectric substrate layer 13, and a conductor-free region 12a surrounded by the conductor 12. The conductor 12 is made of copper.

[0093] The conductor 12 of the noise elimination element 20A includes upper, lower, left, and right side edge portions 21a-21d extending along the four edges of the square, and a central portion 22 located at the center in the vertical direction in FIG. 5 and extending leftward from the right side edge portion 21a. The central portion 22 extends leftward to a length approximately 5 / 6 of the length L20 of one side of the noise elimination element 20A. The central portion 22 includes a first central portion 22a located on the right side edge portion 21a side and having a vertical length approximately 2 / 3 of the length L20 of one side of the noise elimination element 20A. The central portion 22 also includes a second central portion 22b connected to the first central portion 22a and slightly shorter in the vertical direction than the first central portion 22a. The horizontal length of the first central portion 22a is approximately 1 / 2 of the length L20 of one side of the noise elimination element 20A. The region 12a without the conductor 12 is a region surrounded by the upper, lower, left, and right side edge portions 21a to 21d, the first central portion 22a, and the second central portion 22b. The dielectric substrate layer 13 is exposed through the region 12a without the conductor 12.

[0094] The noise elimination element 20B includes upper, lower, left, and right side edge portions 21a-21d extending along the four edges of the square, and a central portion 22 located at the center in the vertical direction in FIG. 5 and extending leftward from the right side edge portion 21a. The central portion 22 extends leftward to a length approximately 5 / 6 of the side length L20 of the noise elimination element 20A. The central portion 22 includes a first central portion 22a located on the right side edge portion 21a side and having a vertical length approximately 2 / 3 of the side length L20. The central portion 22 also includes a second central portion 22b connected to the first central portion 22a and slightly longer in the vertical direction than the first central portion 22a. The horizontal length of the first central portion 22a is approximately 1 / 6 of the side length L20. The region 12a without the conductor 12 is a region surrounded by the upper, lower, left, and right side edge portions 21a to 21d, the first central portion 22a, and the second central portion 22b. The dielectric substrate layer 13 is exposed through the region 12a without the conductor surrounded by the conductor 12.

[0095] The noise elimination element 20C includes side edge portions 21a-21d extending along the four edges of the square, and a central portion 22. The right side edge portion 21a has a horizontal length of approximately 1 / 2 of the side length L20. The central portion 22 is located in the vertical center and extends continuously from the right side edge portion 21a to the left for a length of approximately 5 / 6 of the side length L20 of the noise elimination element 20C. The central portion 22 includes a region 12a without conductors 12, whose vertical length is approximately 2 / 3 of the side length L20, surrounded by the top, bottom, left, and right side edge portions 21 and the central portion 22. The dielectric substrate layer 13 is exposed through the region 12a without conductors 12.

[0096] The phase difference of the noise elimination element 20A is -75 degrees, the phase difference of the noise elimination element 20B is 3.8 degrees, and the phase difference of the noise elimination element 20C is 67 degrees. Furthermore, due to these phase differences of the noise elimination elements 20A to 20C, the reflection angle α2 of the radio wave of the radio wave absorber 11 is designed to be the desired angle of 60 degrees when the incident angle α1 is 0 degree.

[0097] (Configuration of second conductive layer 17) The second conductive layer 17 is a thin-film conductor made of copper and has a thickness L11 of 2 μm. The second conductive layer 17 is formed on the surface of the dielectric substrate layer 13 opposite to the surface on which the first conductive layer 16 is provided.

[0098] (Dielectric Substrate Layer 13) The configurations of the dielectric substrate layer 13 of Examples 1 to 10 are shown in Table 1, and the configurations of the dielectric substrate layer 13 of Comparative Examples 1 to 9 are shown in Table 2. Examples 1 to 10 and Comparative Examples 1 to 9 were designed with a corresponding frequency f of 79 GHz, i.e., a wavelength λ of 3.8 mm. Table 4 shows the configurations of the dielectric substrate layer 13 of Examples 11 to 20, and Table 5 shows the configurations of the dielectric substrate layer 13 of Comparative Examples 10 to 18. Examples 11 to 20 and Comparative Examples 10 to 18 were designed with a corresponding frequency f of 3 GHz, i.e., a wavelength λ of 100 mm. Table 7 shows the configurations of the dielectric substrate layer 13 of Examples 21 to 30, and Table 8 shows the configurations of the dielectric substrate layer 13 of Comparative Examples 19 to 27. Examples 21 to 30 and Comparative Examples 19 to 27 were designed with a corresponding frequency f of 300 GHz, i.e., a wavelength λ of 1 mm.

[0099] (Evaluation Method) A radio wave absorption characteristic test (simulation) was conducted for Examples 1 to 30 and Comparative Examples 1 to 27 (hereinafter also referred to as "samples"). Radio waves with a predetermined frequency, a predetermined incident intensity RI, and an incident angle α1 of 0 degrees were incident on each sample. The reflection intensity RO of the reflected wave with a reflection angle α2 of 0 degrees and the transmission intensity RT of the transmitted wave that passed through the sample and was along the direction of the incident angle α1 were calculated. The incident intensity RI, reflection intensity RO, and transmission intensity RT of the radio waves were calculated by far-field analysis using the full-wave finite element simulation software ANSYS HFSS. The absorption coefficient for each radio wave frequency was calculated using the formula "absorption coefficient = (incident intensity RI - reflected intensity RO - transmitted intensity RT) / incident intensity RI x 100." The samples were square in plan view, with each side length being 3λ or longer.

[0100] In the above tests, radio waves of frequencies of 77 GHz, 78 GHz, 79 GHz, 80 GHz, and 81 GHz were reflected for Examples 1 to 10 and Comparative Examples 1 to 9. Radio waves of frequencies of 2.6 GHz, 2.8 GHz, 3.0 GHz, 3.2 GHz, and 3.4 GHz were reflected for Examples 11 to 20 and Comparative Examples 10 to 18. Radio waves of frequencies of 260 GHz, 280 GHz, 300 GHz, 320 GHz, and 340 GHz were reflected for Examples 21 to 30 and Comparative Examples 19 to 27.

[0101] The case where the absorption rate was 90% or more was evaluated as "◎". The case where the absorption rate was 50% or more but less than 90% was evaluated as "◯". The case where the absorption rate was less than 50% was evaluated as "×".

[0102] (Evaluation Results) The evaluation results for Examples 1 to 10 and Comparative Examples 1 to 9 are shown in Table 3. Examples 1 to 10 were designed to reflect radio waves with a corresponding frequency f of 79 GHz. Examples 1 to 10 satisfied the predetermined range for the substrate design coefficient Db, and also satisfied the predetermined ranges for the PET substrate design coefficient Dbp, FR4 substrate design coefficient Dbf, glass substrate design coefficient Dbg, and silicon substrate design coefficient Dbs, which are determined depending on the material of each dielectric substrate layer. Therefore, Examples 1 to 10 had good radio wave absorption rates. On the other hand, in Comparative Examples 1 to 9, the substrate design coefficient Db was outside the predetermined range, and sufficient absorption rates were not obtained.

[0103] The evaluation results for Examples 11 to 20 and Comparative Examples 10 to 18 are shown in Table 6. Examples 11 to 20 were designed to reflect radio waves with a corresponding frequency f of 3 GHz. Examples 11 to 20 satisfied the predetermined range for the substrate design coefficient Db, and also satisfied the predetermined ranges for the PET substrate design coefficient Dbp, FR4 substrate design coefficient Dbf, glass substrate design coefficient Dbg, and silicon substrate design coefficient Dbs, which are determined according to the material of each dielectric substrate layer. Therefore, Examples 11 to 20 had good radio wave absorption rates. On the other hand, in Comparative Examples 10 to 18, the substrate design coefficient Db was outside the predetermined range, and sufficient absorption rates were not obtained.

[0104] The evaluation results for Examples 21 to 31 and Comparative Examples 19 to 27 are shown in Table 9. Examples 21 to 31 were designed to reflect radio waves with a corresponding frequency f of 300 GHz. Examples 21 to 31 satisfied the predetermined range for the substrate design coefficient Db, and also satisfied the predetermined ranges for the PET substrate design coefficient Dbp, FR4 substrate design coefficient Dbf, glass substrate design coefficient Dbg, and silicon substrate design coefficient Dbs, which are determined depending on the material of each dielectric substrate layer. Therefore, Examples 21 to 31 had good radio wave absorption rates. On the other hand, in Comparative Examples 19 to 27, the substrate design coefficient Db was outside the predetermined range, and sufficient absorption rates were not obtained.

[0105]

[0106]

[0107]

[0108]

[0109]

[0110]

[0111]

[0112]

[0113]

[0114] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit and scope of the present invention. The dimensions, materials, shapes, and relative arrangements of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention. For example, expressions expressing relative or absolute arrangements, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," not only strictly express such arrangements, but also express relative displacements with a tolerance or angle or distance to the extent that the same function is obtained. For example, expressions expressing the equality of things, such as "same," "equal," and "homogeneous," not only express strict equality, but also express tolerance or differences to the extent that the same function is obtained. For example, expressions expressing shapes such as a square or cylindrical shape not only express shapes such as a square or cylindrical shape in the strict geometric sense, but also express shapes including concave and convex portions, chamfered portions, etc., to the extent that the same effect is obtained. The expressions "comprise," "include," "have," "includes," or "have" one component are not exclusive expressions that exclude the presence of other components. In addition, expressions that include "approximately," such as "approximately parallel" or "approximately perpendicular," are sometimes used. For example, "approximately parallel" means that the component is essentially "parallel," and does not mean a strictly "parallel" state, but also includes an error of a few degrees. The same applies to other expressions that include "approximately." In addition, expressions that include "... part," such as "end portion," are sometimes used. For example, "end portion" means a portion having a certain range that includes the "end." The same applies to other expressions that include "... part."

[0115] 11 noise eliminating body 12 conductor 13 dielectric substrate layer 16 first conductive layer 20, 20A to 20C noise eliminating element λ wavelength t thickness of dielectric substrate layer ε relative permittivity of dielectric substrate layer

Claims

1. A noise eliminator comprising first and second conductive layers containing a conductor and a dielectric substrate layer supporting the first and second conductive layers, and absorbing at least a portion of an incident radio wave, wherein the first conductive layer, the dielectric substrate layer and the second conductive layer are laminated in this order, the noise eliminator specularly reflects radio waves, and wherein, where λ is the wavelength of the radio waves, t is the thickness of the dielectric substrate layer and ε is the relative dielectric constant of the dielectric substrate layer, a substrate design coefficient Db=t√ε / λ is defined, and the substrate design coefficient Db satisfies 0.0034≦Db≦0.

12.

2. A noise remover comprising first and second conductive layers containing a conductor and a dielectric substrate layer supporting the first and second conductive layers, and absorbing at least a portion of an incident radio wave, wherein the first conductive layer, the dielectric substrate layer, and the second conductive layer are laminated in this order, the noise remover specularly reflects radio waves, and wherein, assuming that the wavelength of the radio waves is λ, the thickness of the dielectric substrate layer is t, and the dielectric substrate layer is a layer made of PET, a PET substrate design coefficient Dbp=t / λ is defined, and the PET substrate design coefficient Dbp satisfies 0.0017≦Dbp≦0.

065.

3. A noise filter comprising first and second conductive layers containing a conductor and a dielectric substrate layer supporting the first and second conductive layers, and absorbing at least a portion of an incident radio wave, wherein the first conductive layer, the dielectric substrate layer and the second conductive layer are laminated in this order, the noise filter specularly reflects radio waves, and wherein, assuming that the wavelength of the radio waves is λ, the thickness of the dielectric substrate layer is t and the dielectric substrate layer is a layer made of FR4, an FR4 substrate design coefficient Dbf=t / λ is defined, and the FR4 substrate design coefficient Dbf satisfies 0.0017≦Dbf≦0.

057.

4. A noise eliminator comprising first and second conductive layers containing a conductor and a dielectric substrate layer supporting the first and second conductive layers, and absorbing at least a portion of an incident radio wave, wherein the first conductive layer, the dielectric substrate layer, and the second conductive layer are laminated in this order, the noise eliminator specularly reflects radio waves, and wherein, assuming that the wavelength of the radio waves is λ, the thickness of the dielectric substrate layer is t, and the dielectric substrate layer is a layer made of glass, a glass substrate design coefficient Dbg=t / λ is defined, and the glass substrate design coefficient Dbg satisfies 0.0014≦Dbg≦0.

052.

5. A noise remover comprising first and second conductive layers containing a conductor and a dielectric substrate layer supporting the first and second conductive layers, and absorbing at least a portion of an incident radio wave, wherein the first conductive layer, the dielectric substrate layer and the second conductive layer are laminated in this order, the noise remover specularly reflects radio waves, and wherein, assuming that the wavelength of the radio wave is λ, the thickness of the dielectric substrate layer is t and the dielectric substrate layer is a layer made of silicon, a silicon substrate design coefficient Dbs=t / λ is defined, and the silicon substrate design coefficient Dbs satisfies 0.00091≦Dbs≦0.

036.

6. A noise remover according to any one of claims 1 to 5, wherein the first conductive layer comprises a plurality of noise removal elements, and the difference between the phase of the radio wave incident on each of the noise removal elements and the phase of the radio wave reflected from each of the noise removal elements is the same.

7. A noise eliminator comprising first and second conductive layers containing a conductor and a dielectric substrate layer supporting the first and second conductive layers, and absorbing at least a portion of an incident radio wave, wherein the first conductive layer, the dielectric substrate layer and the second conductive layer are laminated in this order, and when reflecting a radio wave, the noise eliminator reflects the radio wave at a reflection angle different from the incident angle, wherein: the wavelength of the radio wave is λ, the thickness of the dielectric substrate layer is t and the relative dielectric constant of the dielectric substrate layer is ε, a substrate design coefficient Db=t√ε / λ is defined, and the substrate design coefficient Db satisfies 0.0034≦Db≦0.

90.

8. A noise eliminator comprising first and second conductive layers containing a conductor and a dielectric substrate layer supporting the first and second conductive layers, and absorbing at least a portion of an incident radio wave, wherein the first conductive layer, the dielectric substrate layer, and the second conductive layer are laminated in this order, and when reflecting a radio wave, the noise eliminator reflects the radio wave at a reflection angle different from the incident angle, wherein the wavelength of the radio wave is λ, the thickness of the dielectric substrate layer is t, and the dielectric substrate layer is a layer made of PET, a PET substrate design coefficient Dbp=t / λ is defined, and the PET substrate design coefficient Dbp satisfies 0.0017≦Dbp≦0.

48.

9. A noise eliminator comprising first and second conductive layers containing a conductor and a dielectric substrate layer supporting the first and second conductive layers, and absorbing at least a portion of an incident radio wave, wherein the first conductive layer, the dielectric substrate layer and the second conductive layer are laminated in this order, and when reflecting a radio wave, the noise eliminator reflects the radio wave at a reflection angle different from the incident angle, wherein an FR4 substrate design coefficient Dbf=t / λ is defined as follows, where λ is the wavelength of the radio wave, t is the thickness of the dielectric substrate layer and the dielectric substrate layer is a layer made of FR4, and the FR4 substrate design coefficient Dbf satisfies 0.0017≦Dbf≦0.

429.

10. A noise eliminator comprising first and second conductive layers containing a conductor and a dielectric substrate layer supporting the first and second conductive layers, and absorbing at least a portion of an incident radio wave, wherein the first conductive layer, the dielectric substrate layer, and the second conductive layer are laminated in this order, and when reflecting a radio wave, the noise eliminator reflects the radio wave at a reflection angle different from the incident angle, wherein the wavelength of the radio wave is λ, the thickness of the dielectric substrate layer is t, and the dielectric substrate layer is a layer made of glass, a glass substrate design coefficient Dbg is defined as Dbg=t / λ, and the glass substrate design coefficient Dbg satisfies 0.0014≦Dbg≦0.

39.

11. A noise eliminator comprising first and second conductive layers containing a conductor and a dielectric substrate layer supporting the first and second conductive layers, and absorbing at least a portion of an incident radio wave, wherein the first conductive layer, the dielectric substrate layer and the second conductive layer are laminated in this order, and when reflecting a radio wave, the noise eliminator reflects the radio wave at a reflection angle different from the incident angle, wherein the wavelength of the radio wave is λ, the thickness of the dielectric substrate layer is t, and the dielectric substrate layer is a layer made of silicon, a silicon substrate design coefficient Dbs=t / λ is defined, and the silicon substrate design coefficient Dbs satisfies 0.00091≦Dbs≦0.

26.

12. A noise remover as described in any one of claims 7 to 11, wherein the first conductive layer comprises a plurality of noise removal elements of two or more different types, and the different types of noise removal elements have different differences in the phase of the radio waves incident on the noise removal elements and the phase of the radio waves reflected from the noise removal elements.

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