Electromagnetic wave absorbing member
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Filing Date
- 2024-08-19
- Publication Date
- 2026-06-25
Abstract
Description
Electromagnetic wave absorbing materials
[0001] The present invention relates to an electromagnetic wave absorbing member.
[0002] Sheet-shaped electromagnetic wave absorbing materials that selectively absorb electromagnetic waves of a predetermined frequency are known. In such electromagnetic wave absorbing materials, electromagnetic waves of a predetermined frequency can be shielded by a thin line pattern of a frequency selective surface (FSS) element formed of a conductor (Patent Document 1).
[0003] Patent No. 6861907
[0004] Here, the impedance of the FSS element changes depending on the direction of polarization of the incident electromagnetic wave, and the electromagnetic wave absorption characteristics may deteriorate. Therefore, when used as an electromagnetic wave absorbing member, if the direction of polarization of the electromagnetic wave incident on the electromagnetic wave absorbing member is different from the direction in which the electromagnetic wave absorption characteristics are high, the electromagnetic wave absorption characteristics may deteriorate.
[0005] The present invention has been made in view of the above-mentioned problems, and has as its object to provide an electromagnetic wave absorbing member that has stable performance regardless of the direction of polarization of the incident electromagnetic wave.
[0006] In order to solve the above problems, the electromagnetic wave absorbing member according to the present invention has the following features.
[0007] [1] An electromagnetic wave absorbing member comprising: a resistive layer having a conductor pattern; the resistive layer having first and second regions having different electromagnetic wave transmission characteristics; the first region having a conductor pattern having a plurality of first arrays, each of which has a plurality of first units, and a plurality of second arrays, each of which has a plurality of second units different from the first units; the second region having a conductor pattern having a plurality of the first arrays and a plurality of the second arrays; in the first region, a plurality of the first units and a plurality of the second units are arranged in a first direction; in the second region, a plurality of the first units and a plurality of the second units are arranged in a second direction different from the first direction; and the first array and the second array are arranged adjacent to each other in the first region and the second region.
[0008] [2] The electromagnetic wave absorbing member according to [1], wherein the first region has a plurality of third arrays in which a plurality of third units different from both the first units and the second units are arranged, the second region has a plurality of the third arrays, the third units in the first region are arranged in the first direction, and the third units in the second region are arranged in the second direction.
[0009] [3] The electromagnetic wave absorbing member according to [1] or [2], wherein the conductor pattern in the second region is a pattern obtained by at least either rotating or inverting the conductor pattern in the first region.
[0010] [4] The electromagnetic wave absorbing member according to any one of [1] to [3], wherein the first region and the second region are repeatedly arranged at regular intervals.
[0011] [5] The resistive layer further has a third region and a fourth region having different electromagnetic wave transmission properties from each other, wherein the third region has a conductor pattern having a plurality of arrays in which a plurality of fourth units are arranged in the first direction, and a plurality of arrays in which a plurality of fifth units different from the fourth units are arranged in the first direction, wherein the fourth region has a conductor pattern having a plurality of arrays in which a plurality of the fourth units are arranged in the second direction, and a plurality of arrays in which a plurality of the fifth units are arranged in the second direction, wherein the first region and the third region differ in at least one of the spacing of the conductor pattern arrangement, the shape of the units included in the array, the size of the units, and the spacing between the units, and wherein the second region and the fourth region differ in at least one of the spacing of the conductor pattern arrangement, the shape of the units included in the array, the size of the units, and the spacing between the units.
[0012] [6] The electromagnetic wave absorbing member according to [5], wherein the third region has a plurality of arrays in which a plurality of sixth units different from both the fourth units and the fifth units are arranged in the first direction, and the fourth region has a plurality of arrays in which a plurality of the sixth units are arranged in the second direction.
[0013] [7] The electromagnetic wave absorbing member according to [5] or [6], wherein the third region and the fourth region are repeatedly arranged at regular intervals.
[0014] [8] The electromagnetic wave absorbing member according to any one of [5] to [7], wherein the conductor pattern in the fourth region is a pattern obtained by at least one of rotating and inverting the conductor pattern in the third region.
[0015] [9] The electromagnetic wave absorbing member according to any one of [5] to [8], wherein the first region is arranged so as to be adjacent to at least one of the third region and the fourth region, and not adjacent to the second region.
[0016]
[10] The electromagnetic wave absorbing member according to any one of [5] to [8], wherein the first region is arranged so as to be adjacent to at least one of the second region and the fourth region, and not adjacent to the third region.
[0017]
[11] The electromagnetic wave absorbing member according to any one of [1] to
[10] , comprising a fifth region having a conductor pattern having a plurality of the first arrays and a plurality of the second arrays, wherein in the fifth region, the first units and the second units are arranged in a third direction different from both the first direction and the second direction, and the first arrays and the second arrays are arranged adjacent to each other.
[0018]
[12] The electromagnetic wave absorbing member according to any one of [1] to
[11] , further comprising a spacer layer and a reflective layer.
[0019] According to the present invention, it is possible to provide an electromagnetic wave absorbing member that has stable performance regardless of the direction of polarization of the incident electromagnetic wave.
[0020] 1A is a cross-sectional view of an electromagnetic wave absorbing member according to the present embodiment; FIG. 1B is a plan view showing an example of a conductor pattern of an electromagnetic wave absorbing member according to the present embodiment; FIG. 1C is a plan view showing a conductor pattern of a comparative electromagnetic wave absorbing member; FIG. 4A is a diagram showing the electromagnetic wave absorption characteristics of a comparative electromagnetic wave absorbing member, and FIG. 4B is a diagram showing the electromagnetic wave absorption characteristics of an electromagnetic wave absorbing member according to the first embodiment; FIG. 5A is a plan view showing a first modified example of a conductor pattern of an electromagnetic wave absorbing member according to the first embodiment; and FIG. 5B is a plan view showing a second modified example of a conductor pattern of an electromagnetic wave absorbing member according to the first embodiment; FIG. 6A is a plan view showing an example of a conductor pattern of an electromagnetic wave absorbing member according to the second embodiment; and FIG. 6B is a plan view showing a reference example of a conductor pattern of an electromagnetic wave absorbing member; and FIG. 7A is a diagram showing the electromagnetic wave absorption characteristics of an electromagnetic wave absorbing member according to the reference example; and FIG. 7B is a diagram showing the electromagnetic wave absorption characteristics of an electromagnetic wave absorbing member according to the second embodiment. 8A is a plan view showing a modified example of one region of a conductor pattern of an electromagnetic wave absorbing member; and FIG. 8B is a plan view showing a modified example of one region of a conductor pattern of an electromagnetic wave absorbing member. 9A is a plan view showing a first modified example of the conductor pattern of the electromagnetic wave absorbing member according to the second embodiment, and 9B is a plan view showing a second modified example of the conductor pattern of the electromagnetic wave absorbing member according to the second embodiment.
[0021] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.
[0022] In this specification, the term "conductor pattern" refers to an aggregate of geometrically shaped units, and refers to an object that selectively transmits electromagnetic waves of a certain frequency. A "conductor pattern" can also be said to have the same function as a so-called antenna. In this specification, "electromagnetic waves in the millimeter wave region" refers to electromagnetic waves with a wavelength of 1 mm to 10 mm. "Electromagnetic waves in the millimeter wave region" can also be said to be electromagnetic waves with a frequency of 30 GHz to 300 GHz. In this specification, the symbol "to" indicating a numerical range means that the numerical values before and after it are included as the lower and upper limits.
[0023] <First embodiment> [Electromagnetic wave absorbing member] Fig. 1 is a cross-sectional view of a surface along the thickness direction of an electromagnetic wave absorbing member according to this embodiment. Fig. 2 is a plan view showing an example of a conductor pattern of the electromagnetic wave absorbing member according to this embodiment. As shown in Fig. 1, the electromagnetic wave absorbing member 1 of this embodiment has a resistance layer 10, a spacer layer 20, and a reflective layer 30. The resistance layer 10, the spacer layer 20, and the reflective layer 30 are laminated in this order.
[0024] The reflective layer 30 is disposed on the other surface (back surface) 10b of the resistive layer 10. The spacer layer 20 is disposed between the resistive layer 10 and the reflective layer 30. That is, the resistive layer 10 and the reflective layer 30 are stacked with the spacer layer 20 interposed therebetween.
[0025] The resistive layer 10 may be a single layer, or may include a substrate 11 and a conductive pattern 12 formed on the substrate 11, as shown in Fig. 1. When the resistive layer 10 is a single layer, the resistive layer 10 is made of the same material as the conductive pattern 12 described below.
[0026] (Resistive Layer) The resistive layer 10 is made of a frequency selective surface (FSS). A frequency selective surface is a surface that can block or transmit only electromagnetic waves of a specific frequency by forming a continuous structure with a shape smaller than the wavelength using a conductive material or the like.
[0027] A conductor pattern 12, which will be described later, is formed on the resistance layer 10. The conductor pattern 12 is formed by arranging, for example, thin metal wires, a conductive thin film, a conductive paste deposit, or the like, on the substrate 11. Examples of metal materials include copper, aluminum, tungsten, iron, molybdenum, nickel, titanium, silver, gold, and alloys containing two or more of these metals (for example, steels such as stainless steel and carbon steel, brass, phosphor bronze, zirconium-copper alloy, beryllium copper, iron-nickel, nichrome, nickel-titanium, Kanthal, Hastelloy, rhenium-tungsten, etc.).
[0028] Examples of materials for the conductive thin film include metal particles, carbon nanoparticles, carbon fiber, etc. The conductive pattern 12 may be formed using a plurality of materials in order to adjust the transmittance characteristics of the resistance layer 10.
[0029] The substrate 11 is a flat plate-like member, and its thickness may be, for example, 5 μm to 500 μm, 15 μm to 200 μm, or 25 μm to 100 μm. The material of the substrate 11 can be selected appropriately depending on the application of the electromagnetic wave absorbing member 1. For example, the substrate 11 may be made of a transparent material in order to provide transparency to the electromagnetic wave absorbing member 1. Alternatively, the substrate 11 may be made of a flexible material in order to provide conformability to curved surfaces of the electromagnetic wave absorbing member 1. The surface of the substrate 11 may be smoothed in order to improve the transparency and three-dimensional formability of the electromagnetic wave absorbing member 1.
[0030] For example, the substrate 11 can be made of a resin. The resin may be a thermoplastic resin or a thermosetting resin. However, when the three-dimensional formability of the electromagnetic wave absorbing member 1 is taken into consideration, the substrate 11 preferably contains a thermoplastic resin. Examples of thermoplastic resins include polyolefin resins, polyester resins, polyester-polyether resins, polyacrylic resins, polystyrene resins, polyimide resins, polyimideamide resins, polyamide resins, polyurethane resins, polycarbonate resins, polyarylate resins, melamine resins, epoxy resins, urethane resins, silicone resins, and fluororesins. Specific examples of polyolefin resins include polypropylene and polyethylene. Specific examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate.
[0031] The substrate 11 may contain optional components within a range that does not impair the effects of the present embodiment. Examples of the optional components include inorganic fillers, colorants, curing agents, antioxidants, light stabilizers, flame retardants, conductive agents, antistatic agents, and plasticizers.
[0032] The thickness, dielectric constant, electrical conductivity, and magnetic permeability of the substrate 11 can be set as appropriate in consideration of further improving the electromagnetic wave absorption performance of the electromagnetic wave absorbing member 1. When the electrical characteristics of the electromagnetic waves to be absorbed are taken into consideration, the substrate 11 may be a layer with a high dielectric constant. If the substrate 11 is a layer with a high dielectric constant, the thickness of the electromagnetic wave absorbing member 1 can be made relatively thin.
[0033] The resistance layer 10 can be produced, for example, by the following method. First, a substrate 11 is prepared. Next, a conductor pattern, which will be described later, is formed on one surface 11a of the substrate 11. When forming each conductor pattern, the conductor pattern is formed so that the frequency value at which the amount of electromagnetic wave transmitted by each conductor pattern shows a maximum value is a predetermined value [GHz]. The order in which each conductor pattern is formed is not particularly limited. Each conductor pattern may be formed in the same process, or may be formed in separate processes.
[0034] The method for forming each conductor pattern is not particularly limited as long as it is possible to absorb a predetermined frequency in the configuration of the electromagnetic wave absorbing member. Examples of the method for forming each conductor pattern include the following: (1) a printing method in which each conductor pattern is printed on one surface 11 a of the substrate 11 using a conductive paste, (2) a development method in which each conductor pattern is developed on one surface 11 a of the substrate 11, (3) a method in which a metal thin film is provided on one surface 11 a of the substrate 11 by sputtering, vacuum deposition, or lamination of a metal foil, and a pattern of the metal thin film is formed on one surface 11 a of the substrate 11 by photolithography, and (4) a method in which a metal wire is disposed on one surface 11 a of the substrate 11.
[0035] (Spacer Layer) The spacer layer 20 is provided on the other surface 10b of the resistive layer 10. The spacer layer 20 has two surfaces 20a and 20b. One surface 20a of the spacer layer 20 faces the other surface 10b of the resistive layer 10. A reflective layer 30 is provided on the other surface 20b of the spacer layer 20. The spacer layer 20 may have a single-layer structure or a multi-layer structure.
[0036] The material of the spacer layer 20 can be appropriately selected depending on the application, and examples thereof include plastic film, paper, cloth, nonwoven fabric, rubber sheet, and foam sheet. Among these, a foam sheet is preferred from the viewpoint of easily achieving weight reduction while increasing thickness. For example, a foam sheet formed by foaming the resin constituting the plastic film and forming it into a sheet can be used. Specific examples of foam sheets include polyethylene foam, polypropylene foam, and polyurethane foam.
[0037] When considering the wavelength shortening effect of the spacer layer 20, the thickness of the spacer layer 20 is appropriately changed according to the wavelength of the electromagnetic wave to be absorbed and the relative dielectric constant of the spacer layer 20. When considering the wavelength shortening effect of the spacer layer 20, it is preferable that the thickness of the spacer layer 20 satisfy the following formula (1): (Thickness of the spacer layer 20 in the z-axis direction) = (λ) × (¼) / (ε) １／２...Equation (1) where λ is the wavelength of the incident electromagnetic wave, and ε is the relative dielectric constant of the spacer layer 20. The thickness of the spacer layer 20 may be adjusted as appropriate to adjust the absorption characteristics of the electromagnetic wave absorbing member 1. For example, the thickness can be changed within a range of 0.1 to 3.0 times the thickness of the spacer layer 20 obtained by the above equation (1).
[0038] When the relationship between the thickness of the spacer layer 20 and the wavelength λ satisfies the above formula (1), the electromagnetic wave absorbing member 1 has a so-called λ / 4 structure. In this case, the phase between the electromagnetic wave that passes through the spacer layer 20 and is reflected by the reflective layer 30 and the electromagnetic wave that is reflected by the resistive layer 10 is inverted, i.e., the phase difference is 180 degrees. This reduces the power of the electromagnetic wave reflected from the electromagnetic wave absorbing member 1. The thickness of the spacer layer 20 can be appropriately set depending on the wavelength λ of the electromagnetic wave to be absorbed by the electromagnetic wave absorbing member 1. The thickness of the spacer layer 20 may be, for example, 25 μm to 5000 μm, 300 μm to 4000 μm, or 1000 μm to 3000 μm. The spacer layer 20 may be made of a material with a high dielectric constant. If the spacer layer 20 is a layer with a high dielectric constant, the thickness of the spacer layer 20 can be made relatively thin. When the dielectric constant of the spacer layer 20 is taken into consideration, the spacer layer 20 may contain at least one selected from the group consisting of barium titanate, titanium oxide, and strontium titanate.
[0039] (Reflective Layer) The reflective layer 30 has two surfaces 30a and 30b. One surface 30a of the reflective layer 30 faces the other surface 20b of the spacer layer 20. The reflective layer 30 is not particularly limited as long as it can reflect the electromagnetic waves that arrive at the surface of the electromagnetic wave absorbing member 1 and pass through the electromagnetic wave absorbing member 1. A portion of the electromagnetic waves that arrive at the electromagnetic wave absorbing member 1 is reflected by or absorbed by the resistive layer 10. On the other hand, the electromagnetic waves that are not reflected or absorbed by the resistive layer 10 pass through the resistive layer 10. The electromagnetic waves that pass through the resistive layer 10 are reflected by the reflective layer 30 toward the resistive layer 10.
[0040] For example, if the reflective layer 30 has conductivity in the surface direction of either of the two surfaces 30a, 30b, it can reflect electromagnetic waves that have passed through the resistive layer 10. Specifically, a resin film such as polyethylene terephthalate to which a metal foil such as aluminum foil or copper foil, or a metal plate such as a copper plate is attached can be used as the reflective layer 30. Instead of the metal foil or metal plate, a transparent conductive film such as ITO, or a mesh sheet formed of metal wires, etc. may also be used.
[0041] When the spacer layer 20 is formed on a conductive material such as a metal, the conductive material such as a metal serves as the reflective layer 30, and therefore the reflective layer 30 can be omitted.
[0042] For the purpose of applying the electromagnetic wave absorbing member 1 to the surfaces of various articles, an adhesive layer may be provided on the other surface 30b of the reflective layer 30. When an adhesive layer is provided on the other surface 30b of the reflective layer 30, a release film may be provided on the surface of the adhesive layer opposite to the side in contact with surface 30b. The release film is removed when the electromagnetic wave absorbing member 1 is used. Covering the adhesive surface with the release film improves handling during distribution.
[0043] Examples of adhesives constituting the adhesive layer include heat-sealing adhesives that bond by heat; adhesives that develop adhesiveness by wetting; and pressure-sensitive adhesives (adhesives) that bond by pressure. Among these, adhesives (pressure-sensitive adhesives) can be selected from the viewpoint of simplicity. Specific examples of adhesives include acrylic adhesives, urethane adhesives, rubber adhesives, polyester adhesives, silicone adhesives, polyvinyl ether adhesives, and the like. Among these, at least one selected from the group consisting of acrylic adhesives, urethane adhesives, and rubber adhesives can be used.
[0044] The electromagnetic wave absorbing member 1 of this embodiment may also include a protective layer formed on one surface (front surface) 10a of the resistance layer 10. The protective layer is not particularly limited as long as it can protect the resistance layer 10.
[0045] [Conductor Pattern] Next, the conductor pattern 12 will be described in detail with reference to FIG. 2 . FIG. 2 is a plan view schematically illustrating the resistance layer 10. The conductor pattern 12 includes a first region 200 and a second region 210. As shown in FIG. 2 , the first region 200 and the second region 210 are repeatedly arranged at regular intervals in both the X direction and the Y direction to form the conductor pattern 12. Note that the intervals in the X direction and the Y direction may be the same or different. Note that the regions 200 and 210 will be described as being quadrangular, but are not limited thereto and may have any shape, such as a triangle or a hexagon.
[0046] The electromagnetic wave transmission characteristic represents the ratio of the intensity of the electromagnetic wave transmitted through the surface 10b (electromagnetic wave transmittance) when an electromagnetic wave of a predetermined intensity is incident on the surface 10a of the resistive layer 10. For example, the electromagnetic wave transmission characteristic corresponds to the frequency of the electromagnetic wave and the electromagnetic wave transmittance for a plurality of different frequencies. For another example, the electromagnetic wave transmission characteristic corresponds to the polarization direction of the incident electromagnetic wave and the frequency of the electromagnetic wave and the electromagnetic wave transmittance. The electromagnetic wave transmission characteristic may be defined for the entire resistive layer 10, or may be defined for each of the first region 200 and the second region 210. Furthermore, the electromagnetic wave transmission characteristic may be defined for each of the first unit u1 to third unit u3 of the conductor pattern 12 described below, or for each of the first array 202 to third array 204 in which a plurality of units are arranged.
[0047] The first region 200 includes a first array 202 in which a plurality of first units u1 are arranged, a second array 203 in which a plurality of second units u2 are arranged, and a third array 204 in which a plurality of third units u3 are arranged. As shown in FIG. 2 , the first region 200 includes a plurality of first to third arrays 202 to 204, respectively.
[0048] In addition, in the first region 200, the first to third arrays 202 to 204 extend in a first direction indicated by an arrow 201 (hereinafter, sometimes referred to as direction 201), i.e., "units," which are geometric figures included in the arrays, are repeatedly arranged in the first direction at predetermined intervals.
[0049] The second region 210 includes a first array 212 in which a plurality of first units u1 are arranged, a second array 213 in which a plurality of second units u2 are arranged, and a third array 214 in which a plurality of third units u3 are arranged.
[0050] In addition, in the second region 210, the first to third arrays 212 to 214 extend in a second direction indicated by an arrow 211 (hereinafter, sometimes referred to as direction 211), i.e., in the second region 210, the units are repeatedly arranged in the second direction 211 at predetermined intervals.
[0051] The spacing between units within an array is not particularly limited. The spacing between units may be regular or irregular. The spacing between multiple arrays is not particularly limited. The spacing between multiple arrays may be regular or irregular. In this embodiment, the spacing between units is the same in the first region 200 and the second region 210. This allows the spacing between units u1 to u3 in the first to third arrays 202 to 204 of the first region 200 to be determined, and then the arrangement of the conductors in the second region 210 can be determined by rotating the first region 200 in the XY plane. In another example, after determining the arrangement of the units in the first region 200, the arrangement of the units in the second region 210 can be determined by flipping the first region 200 in a predetermined direction on the XY plane shown in FIG. 2 . In this way, after determining the arrangement of units in the first region 200, the arrangement of units in the second region 210 can be determined by at least one of rotating and inverting the arrangement of units in the first region 200, thereby easily designing the arrangement of units in the second region 210.
[0052] However, the arrangement patterns of the units may be designed separately for the first region 200 and the second region 210. Furthermore, the impedance may change due to coupling between the units near the boundary between the first region 200 and the second region 210. For this reason, the intervals between the units adjacent to the boundary between the first region 200 and the second region 210 may be changed from d1 to d3 in FIG.
[0053] (First Array) As described above, the first arrays 202 and 212 are made up of a plurality of first units u1. Each of the first units u1 is a geometric figure.
[0054] In other words, the first arrays 202 and 212 can be considered as a collection of first units u1, which are geometric figures. Each of the first units u1 functions as an antenna. The first arrays 202 and 212 may be, for example, a thin-line pattern of FSS elements.
[0055] As shown in Figure 2, the shape of the first unit u1 is a cross that is symmetrical in both the vertical and horizontal directions. Specifically, the first unit u1 has one cross portion S1 and four end portions T1. The cross portion S1 includes two straight line portions that intersect at right angles, and the two straight line portions are arranged so that they intersect at 45 degrees and -45 degrees with respect to the direction in which the units u1 are arranged. Linear end portions T1 contact both ends of the two straight line portions included in the cross portion S1 so as to be perpendicular to the respective straight line portions.
[0056] By adjusting the length and width of the straight portions of the cross portion S1 of the first unit u1 and the length and width of each of the four end portions T1, the electromagnetic wave transmission characteristics of the first unit u1, which functions as a single antenna, can be adjusted.
[0057] However, the shape of the first unit u1 is not limited to a cross shape. The shape of the first unit u1 is not particularly limited as long as the frequency value at which the amount of electromagnetic wave transmitted through the first arrays 202 and 212 reaches a maximum value is A [GHz]. For example, the shape of the figure that is the first unit u1 may be a circle, an annular shape, a linear shape, a square shape, a polygonal shape, an H-shape, a Y-shape, a V-shape, etc.
[0058] In this embodiment, the shapes of the multiple first units u1 included in one array are described as being identical to each other. However, the shapes of any of the multiple first units u1 do not have to be identical to each other. In another example, the shapes of the multiple first units u1 may be identical to each other or different from each other as long as the transmission characteristics can be adjusted to the target frequency.
[0059] The first arrays 202 and 212 selectively transmit electromagnetic waves having a frequency of A [GHz]. The frequency value A [GHz] is the frequency value at which the amount of electromagnetic waves transmitted by the first arrays 202 and 212 reaches a maximum value in the range of 20 GHz to 110 GHz.
[0060] The first arrays 202, 212 transmit electromagnetic waves having a frequency of A [GHz] as determined by the above-described method X.
[0061] In the resistive layer 10 of this embodiment, the frequency value A is, for example, 20 GHz to 110 GHz, preferably 60 GHz to 100 GHz, and more preferably 65 GHz to 95 GHz, for example, 70 GHz to 90 GHz. When the frequency value A is within the above range, the resistive layer 10 can transmit electromagnetic waves in the millimeter wave region, making it easier to apply to automobile parts, road peripheral members, building exterior wall related materials, windows, communication devices, radio telescopes, etc.
[0062] The spacing between the ends of the first unit u1 is not particularly limited as long as the transmission characteristics can be adjusted to the desired frequency. For example, the spacing between the ends of the first unit u1 may all be the same or may be different from each other. However, it is preferable that the spacing between the ends of the first unit u1 be the same, as this makes it easier to design a resistive layer 10 that is less susceptible to the influence of the surrounding environment and improves the accuracy of the frequency band of the transmitted electromagnetic waves during manufacturing.
[0063] 2, the second arrays 203 and 213 are composed of a plurality of second units u2. Similar to the first units u1, the second units u2 are cross-shaped and symmetrical in both the vertical and horizontal directions. Specifically, the second units u2 have one cross portion S2 and four end portions T2, and either the dimensions of S2 or T2 differ from the dimensions of the first units u1.
[0064] The dimensions S2 and T2 of the second arrays 203, 213 are designed to selectively transmit electromagnetic waves having a frequency of B [GHz] that satisfies the following formula (2). The frequency value B [GHz] is the frequency value at which the amount of electromagnetic waves transmitted by the second arrays 203, 213 reaches a maximum. The frequency value B [GHz] satisfies the following formula (2).
[0065] 1.037×A≦B≦1.30×A (2) As shown in the above formula (2), the second arrays 203, 213 transmit electromagnetic waves having a frequency of 1.037×A [GHz] to 1.30×A [GHz]. It is preferable that the second arrays 203, 213 transmit electromagnetic waves having a frequency of 1.17×A [GHz] to 1.25×A [GHz].
[0066] Because the second arrays 203, 213 transmit electromagnetic waves with frequencies of 1.037×A [GHz] or higher, the peaks of the electromagnetic wave transmission amount through the second arrays 203, 213 and the peaks of the electromagnetic wave transmission amount through the first arrays 202, 212 sufficiently overlap in the frequency band higher than A [GHz]. As a result, the frequency band of electromagnetic waves that can be absorbed by the entire electromagnetic wave absorbing member is expanded to the frequency band higher than A [GHz], compared to an electromagnetic wave absorbing member having only the first arrays 202, 212. In other words, the frequency band of electromagnetic waves that can be absorbed by the entire electromagnetic wave absorbing member can be broadened to the higher frequency side.
[0067] Because the second arrays 203, 213 transmit electromagnetic waves with frequencies of 1.30×A [GHz] or less, the frequency difference between the peak of the amount of electromagnetic wave transmitted by the second arrays 203, 213 and the peak of the amount of electromagnetic wave transmitted by the first arrays 202, 212 becomes small in the frequency band higher than A [GHz]. As a result, a single peak is formed at which the amount of electromagnetic wave absorbed by the entire electromagnetic wave absorbing material 1 reaches a local maximum. From the above, because the second arrays 203, 213 transmit electromagnetic waves with frequencies of 1.037×A [GHz] to 1.30×A [GHz], the amount of electromagnetic wave absorbed by the entire electromagnetic wave absorbing material is extended into the higher frequency band.
[0068] The material of the second unit u2 constituting the second array 203, 213 is not particularly limited as long as it is capable of transmitting electromagnetic waves of B [GHz], and is not particularly limited as long as the transmission characteristics can be adjusted to the desired frequency.
[0069] (Third Array) As shown in FIG. 2, the third arrays 204 and 214 are made up of a plurality of third units u3.
[0070] The third unit u3 has a cross shape that is vertically and horizontally symmetrical to the first unit u1. Specifically, the third unit u3 has one cross portion S3 and four end portions T3, and any of the dimensions of S3 and T3 differs from the dimensions of the first unit u1 and the second unit u2.
[0071] The dimensions S3 and T3 of the third arrays 204, 214 are designed to selectively transmit electromagnetic waves having a frequency of C [GHz] that satisfies the following formula (3). The frequency value C [GHz] is the frequency value at which the amount of electromagnetic waves transmitted by the third arrays 204, 214 exhibits a maximum value. The frequency value C [GHz] satisfies the following formula (3).
[0072] 0.60×A≦C≦0.963×A (3) As shown in the above formula (3), the third arrays 204, 214 transmit electromagnetic waves having a frequency of 0.60×A [GHz] to 0.963×A [GHz]. It is preferable that the third arrays 204, 214 transmit electromagnetic waves having a frequency of 0.60×A [GHz] to 0.83×A [GHz].
[0073] Because the third arrays 204, 214 transmit electromagnetic waves with frequencies of 0.60×A [GHz] or higher, in the frequency band lower than A [GHz], the difference in frequency between the peak of the amount of electromagnetic wave transmitted by the third arrays 204, 214 and the peak of the amount of electromagnetic wave transmitted by the first arrays 202, 212 becomes small. As a result, a single peak is formed at which the amount of electromagnetic wave transmitted through the entire resistive layer 10 reaches a maximum value.
[0074] Because the third arrays 204, 214 transmit electromagnetic waves with frequencies of 0.963×A [GHz] or less, the peak of the amount of electromagnetic wave transmission by the third arrays 204, 214 fully overlaps with the peak of the amount of electromagnetic wave transmission by the first arrays 202, 212 in the frequency band lower than A [GHz]. As a result, the frequency band of electromagnetic waves that can be absorbed by the electromagnetic wave absorbing member is expanded to the frequency band lower than A [GHz], compared to a film having only the first arrays 202, 212. In other words, the frequency band of electromagnetic waves that can be absorbed by the entire electromagnetic wave absorbing member can be broadened to the lower frequency side.
[0075] As described above, the third arrays 204, 214 transmit electromagnetic waves with frequencies between 0.60×A [GHz] and 0.963×A [GHz], and therefore the amount of electromagnetic waves transmitted through the entire resistive layer 10 is extended to the lower frequency band.
[0076] The material of the third unit u3 constituting the third array 204, 214 is not particularly limited as long as it is capable of transmitting electromagnetic waves of C [GHz], and is not particularly limited as long as the transmission characteristics can be adjusted to the desired frequency.
[0077] 2 , in both the first region 200 and the second region 210, the first arrays 202 and 212, the second arrays 203 and 213, and the third arrays 204 and 214 are arranged adjacent to one another. Because the first arrays 202 and 212, the second arrays 203 and 213, and the third arrays 204 and 214 are arranged adjacent to one another on the substrate 11, the frequency band of the electromagnetic waves selectively transmitted by the second arrays 203 and 213 and the frequency band of the electromagnetic waves selectively transmitted by the third arrays 204 and 214 overlap, based on the frequency value A [GHz] of the peak position of the electromagnetic waves selectively transmitted by the first arrays 202 and 212. As a result, the transmission range of the electromagnetic waves transmitted through the entire resistive layer 10 is easily expanded toward both the high-frequency side and the low-frequency side, based on the frequency value A [GHz] of the peak position.
[0078] The distance d1 between the first unit u1 and the second unit u2, the distance d2 between the second unit u2 and the third unit u3, and the distance d3 between the third unit u3 and the first unit u1, shown in FIG. 2, may be the same as or different from one another. The distance d1 may be, for example, 0.2 mm to 4 mm, 0.3 mm to 2 mm, or 0.5 mm to 1 mm. The distance d2 may be, for example, 0.2 mm to 4 mm, 0.3 mm to 2 mm, or 0.5 mm to 1 mm. The distance d3 may be, for example, 0.2 mm to 4 mm, 0.3 mm to 2 mm, or 0.5 mm to 1 mm. When the distances d1, d2, and d3 are each within the above-described ranges, the transmission range of electromagnetic waves transmitted through the entire resistive layer 10 is likely to be further expanded relative to the frequency value A [GHz] at the peak position. As described above, the values of d1 to d3 may be different between the first region 200 and the second region 210.
[0079] In the resistive layer 10, the first unit u1, the second unit u2, and the third unit u3 have the same shape. However, the shapes of the first unit u1, the second unit u2, and the third unit u3 do not have to be identical to each other. That is, in other examples of the present invention, the shapes of the first unit u1, the second unit u2, and the third unit u3 may be the same or different from each other. Furthermore, in the example of FIG. 2, the first unit u1, the second unit u2, and the third unit u3 are illustrated as having the same orientation, but the orientations of adjacent two units in each of the first unit u1, the second unit u2, and the third unit u3 may be different.
[0080] 3 shows a conductor pattern 300 of an electromagnetic wave absorbing member that is composed of only a single region. In the conductor pattern 300 of the electromagnetic wave absorbing member, the first unit u1, the second unit u2, and the third unit u3 described with reference to FIG. 2 are arranged along a single direction 301.
[0081] 4A shows the absorption characteristics of the electromagnetic wave absorbing member 1 having the comparative conductive pattern 300. The absorption rate is the ratio of the incident signal intensity P inAs a result, the reflected signal strength P ref Let Ra be the absorption coefficient, and Ra = 1-P ref / P in The Ra is calculated as follows. The polarization direction of the incident electromagnetic wave is set to 0 degrees (0 deg) when it is vertically polarized, i.e., when the electric field oscillates in the Y direction, and the tilt of the electric field oscillates in relation to the Y axis in Figure 3 is rotated in 15-degree increments to measure Ra. For example, when it is horizontally polarized, i.e., when the electric field oscillates in the X direction, it is calculated as 90 degrees (90 deg).
[0082] When the polarization direction is 30 degrees, 45 degrees, or 60 degrees, the absorption rate may fall below 96% between 76 and 76.2 GHz, as shown in Figure 4A. It can also be seen that the absorption rate varies by up to about 5% depending on the polarization direction.
[0083] The measurement results of the absorption rate of the electromagnetic wave absorbing member 1 of Fig. 2 are shown in Fig. 4B. The direction of polarization of the electromagnetic waves is the same as in Fig. 4A. As shown in Fig. 4B, it can be seen that the absorption rate of the electromagnetic wave absorbing member 1 according to this embodiment exceeds 96% regardless of the direction of polarization. It can also be seen that the difference in absorption rate due to differences in the direction of polarization is suppressed to about 3%.
[0084] As shown in Figure 4A, the electromagnetic wave absorption characteristics of the electromagnetic wave absorbing member having the comparative conductor pattern 300 can change depending on the orientation of the conductor pattern relative to the polarization direction of the incident electromagnetic wave. Therefore, when using the electromagnetic wave absorbing member having the comparative conductor pattern 300, it was necessary to adjust the orientation of the electromagnetic wave absorbing member 1 so that the polarization direction of the electromagnetic wave incident on the electromagnetic wave absorbing member, which exhibits high absorption characteristics, matches the polarization direction of the electromagnetic wave incident on the electromagnetic wave absorbing member. Furthermore, when inspecting multiple high-frequency components that emit different polarization directions, it was necessary to change the orientation of the electromagnetic wave absorbing member for each inspection. Thus, with the electromagnetic wave absorbing member having the comparative conductor pattern 300, the electromagnetic wave absorption characteristics could change depending on the polarization direction of the incident electromagnetic wave.
[0085] On the other hand, the electromagnetic wave absorbing member 1 having a conductor pattern according to this embodiment has a plurality of regions 200, 210 that have different properties depending on the polarization direction of the incident electromagnetic wave, so that even when the polarization direction of the incident electromagnetic wave changes, the high absorption properties of the electromagnetic wave absorbing member 1 can be maintained. This allows the electromagnetic wave absorbing member 1 to be used without having to consider the polarization direction of the incident electromagnetic wave, thereby improving the convenience for the user when using the electromagnetic wave absorbing member.
[0086] Furthermore, in the electromagnetic wave absorbing member 1 according to this embodiment, two or more types of units are arranged side by side in one region, which allows the frequency band in which electromagnetic waves are absorbed by the electromagnetic wave absorbing member 1 to be broadened.
[0087] 2, the first regions 200 and the second regions 210 are illustrated as being repeatedly arranged at regular intervals in the X and Y directions. However, the arrangement of the first regions 200 and the second regions 210 may be in different patterns.
[0088] 5A in Fig. 5 shows a conductor pattern 600 of an electromagnetic wave absorbing member according to a first modified example. Note that the same reference numerals are used for the same components as in Fig. 2, and descriptions thereof will be omitted. In the conductor pattern 600 according to the first modified example, the first regions 200 and the second regions 210 are alternately and repeatedly arranged in one direction. That is, as shown in Fig. 2, the first regions 200 and the second regions 210 may be alternately and repeatedly arranged two-dimensionally, or as shown in Fig. 5A in Fig. 5, the first regions 200 and the second regions 210 may be alternately and repeatedly arranged one-dimensionally.
[0089] 2 shows a first region 200 in which conductor units are arranged in a first direction and a second region 210 in which the units are arranged in a second direction, which are repeatedly arranged at regular intervals. In one example, the conductor pattern may additionally include a region in which conductor units are arranged in a direction different from the first and second directions.
[0090] 5B shows a conductor pattern 700 of an electromagnetic wave absorbing member according to a second modification. Note that the same reference numerals are used for the same components as those in FIG. 2 , and a description thereof will be omitted. The conductor pattern 700 of the electromagnetic wave absorbing member includes a region 710 in which units are arranged in a direction indicated by an arrow 711 (hereinafter referred to as direction 711), a region 720 in which units are arranged in a direction indicated by an arrow 721 (hereinafter referred to as direction 721), a region 730 in which units are arranged in a direction indicated by an arrow 731 (hereinafter referred to as direction 731), and a region 740 in which units are arranged in a direction indicated by an arrow 741 (hereinafter referred to as direction 741). Note that regions 710, 720, 730, and 740 have the same configuration as regions 200 and 210 described with reference to FIG. 2, except that the directions in which the units are arranged are different. In the regions 710, 720, 730, and 740, the directions 711, 721, 731, and 741 in which the units are arranged are different from one another.
[0091] In the example of Fig. 5B, the direction in which the units are arranged is illustrated as being in 45-degree increments, but this is not limited thereto and may be, for example, in 22.5-degree increments. Also, in Fig. 2, the units are arranged in two directions, the direction along the arrow 201 and the direction along the arrow 211, while in Fig. 5B, the units are illustrated as being arranged in four directions, the directions 711, 721, 731, and 741. However, it is sufficient that there are multiple directions in which the units are arranged in the conductor pattern, and the units may be arranged in three directions, or in five or more directions.
[0092] Also, as described with reference to FIG. 2, the arrangement of units in regions 710 to 740 may be determined individually, or may be determined by rotating and / or flipping the arrangement of units in one region.
[0093] 6A, an electromagnetic wave absorbing member 1 according to a second embodiment includes a conductor pattern 800 having a first region 200A, a second region 210A, a third region 220A, and a fourth region 230A (hereinafter, these may be referred to as regions 200A to 230A without distinction). Note that a description of the same configuration as in the first embodiment will be omitted.
[0094] The first region 200A has the same configuration as the region 200 described with reference to FIG. 2, and has first to third arrays 202 to 204 in which units u1 to u3 are arranged in a first direction 201.
[0095] The second region 210A has a configuration similar to that of the second region 210 described with reference to Fig. 2. The second region 210A has units u1 to u3 similar to those of the first region 200A, but unlike the first region 200A, the units u1 to u3 are arranged along a third direction 211 that is different from the first direction 201. However, in the second region 210A, in addition to the direction in which the units are arranged, at least one of the shape of the units u1 to u3, any dimensions and spacing, and spacing between the arrays may be changed compared to the first region 200A.
[0096] The third region 220A differs from the adjacent first region 200A in at least one of the shape of the first to third units u1 to u3, the dimensions of any of them, the spacing between them, and the spacing between the arrays. This causes the regions 200A and 220A to have different electromagnetic wave transmission characteristics. Note that in this embodiment, the first direction 201 in which the units are arranged in the first region 200A and the second direction 211 in which the units are arranged in the third region 220A are described as being the same, but it goes without saying that the first direction 201 and the second direction 211 may be different.
[0097] For example, if the first region 200A has multiple types of units as described above, the third region 220A preferably has the same types of units, and at least one of the surface area, thickness, and arrangement interval of the units is reduced by a predetermined amount. Specifically, the surface area or thickness of each of the units in the third region 220A is preferably 99 to 60%, and more preferably 95 to 80%, of the first unit u1 to the third unit u3 in the first region 200A. Furthermore, the arrangement interval of the third region 220A is preferably 99 to 60%, and more preferably 90 to 70%, of that of the first region 200A.
[0098] The fourth region 230A has units u1 to u3 similar to those of the third region 220A, but unlike the third region 220A, the units u1 to u3 are arranged along a fourth direction 231 that is different from the third direction 221. However, in the fourth region 230A, in addition to the direction in which the units are arranged, at least one of the shape of the units u1 to u3, any dimension and spacing, and spacing between the arrays may be changed compared to the third region 220A.
[0099] As a reference example, Fig. 6B shows a conductor pattern 900 of an electromagnetic wave absorbing member that is composed only of first regions 200A and third regions 220A. In the conductor pattern 900, the first regions 200A and third regions 220A described with reference to Fig. 6A are repeatedly and alternately arranged.
[0100] 7A of FIG. 7 shows the absorption characteristics of the electromagnetic wave absorbing member 1 having the conductor pattern 900 of the reference example. The polarization direction of the electromagnetic wave is the same as in FIGS. 4A and 4B. As shown in FIG. 7A of FIG. 7, the difference in absorption rate around 79 GHz between when the polarization direction of the incident electromagnetic wave is 45 degrees and when it is 135 degrees is 8% or more. In other words, the absorption rate varies by 8% or more depending on the angle of the conductor pattern 900 relative to the polarization direction of the incident electromagnetic wave. It can also be seen that when the polarization direction of the incident electromagnetic wave is 30, 45, 60, or 75 degrees, the absorption rate of the conductor pattern 900 is less than 95% in the range of 78 to 80.5 GHz.
[0101] 7B of Fig. 7 shows the absorption characteristics of the electromagnetic wave absorbing member 1 having the conductor pattern 800 shown in Fig. 6A. The direction of polarization of the electromagnetic wave is the same as that shown in Fig. 7A. As shown in Fig. 5A of Fig. 5, it can be seen that the absorption rate of the conductor pattern 800 exceeds 95% in the range of 76 to 81 GHz for all directions of polarization of the incident electromagnetic wave. It can also be seen that the variation in absorption rate depending on the angle of the conductor pattern 800 with respect to the direction of polarization of the incident electromagnetic wave is suppressed to less than 5%.
[0102] 7A and 7B, the electromagnetic wave absorption characteristics of the electromagnetic wave absorbing member having the conductor pattern 900 of the reference example can change depending on the orientation of the conductor pattern relative to the polarization direction of the incident electromagnetic wave. Therefore, when using the electromagnetic wave absorbing member having the conductor pattern 900 of the reference example, it was necessary to adjust the orientation of the electromagnetic wave absorbing member 1 so that the polarization direction that exhibits high absorption characteristics when electromagnetic waves are incident on the electromagnetic wave absorbing member coincides with the polarization direction of the electromagnetic waves incident on the electromagnetic wave absorbing member. Furthermore, when inspecting multiple high-frequency components that emit polarized waves with different directions, it was necessary to change the orientation of the electromagnetic wave absorbing member for each inspection.
[0103] On the other hand, the electromagnetic wave absorbing member 1 having the conductor pattern 800 according to this embodiment has a plurality of regions 200A, 210A, 220A, and 230A that have different characteristics depending on the polarization direction of the incident electromagnetic wave, so that even when the polarization direction of the incident electromagnetic wave changes, the high absorption characteristics of the electromagnetic wave absorbing member 1 can be maintained. This allows the electromagnetic wave absorbing member 1 to be used without having to consider the polarization direction of the incident electromagnetic wave, thereby improving the convenience for the user when using the electromagnetic wave absorbing member 1.
[0104] Next, Table 1 shows the changes in the absorption characteristics of electromagnetic waves in the range of 76 to 81 GHz when the thickness of the spacer layer 20 is changed for the conductor pattern 300 shown in Figure 3, the conductor pattern 900 shown in Figure 6B, and the conductor pattern 800 shown in Figure 6A.
[0105]
[0106] As shown in Table 1, for the conductor pattern 300 shown in Figure 3, when the spacer layer 20 is 1.8 mm thick, the maximum absorption rate at 76 to 81 GHz is 87.0%, and when the spacer layer 20 is 1.8 mm thick, the minimum absorption rate at 76 to 81 GHz is 68.4%. For the conductor pattern 900 shown in Figure 6B, when the spacer layer 20 is 1.8 mm thick, the maximum absorption rate at 76 to 81 GHz is 89.4%, and when the spacer layer 20 is 1.8 mm thick, the minimum absorption rate at 76 to 81 GHz is 85.1%. For the conductor pattern 800 shown in Figure 6A, when the spacer layer 20 is 2.2 mm thick, the maximum absorption rate at 76 to 81 GHz is 91.6%, and when the spacer layer 20 is 1.8 mm thick, the minimum absorption rate at 76 to 81 GHz is 87.6%. As described above, it can be seen that the conductor pattern 800 according to this embodiment exhibits stable absorption characteristics even when the thickness of the spacer layer varies greatly.
[0107] Furthermore, in the electromagnetic wave absorbing member 1 according to this embodiment, two or more types of units are arranged side by side in one region, which allows the frequency band in which electromagnetic waves are absorbed by the electromagnetic wave absorbing member 1 to be broadened.
[0108] [First Modification] In the example of Figure 6A in Figure 6, the first region 200A and the third region 220A are regions that differ in at least one of the shape, size, and spacing of the units u1 to u3 and the spacing between the units, and the second region 210A and the fourth region 230A are regions that differ in the direction in which the units are arranged compared to the first region 200A and the third region 220A, respectively. In one example, three or more types of regions may be arranged that have the same arrangement direction but differ in at least one of the shape, size, and spacing of the units u1 to u3 included in the regions and the spacing between the units. Below, with reference to Figures 8 and 9, a conductor pattern of an electromagnetic wave absorbing member in which three or more types of regions are arranged and have the same arrangement direction will be described.
[0109] FIG. 8A shows some regions of a conductor pattern according to a first modified example. The conductor pattern according to the first modified example has regions 200A to 200C. As described with reference to FIG. 2, in region 200A, units u1 to u3 are arranged along direction 201. In regions 200B and 200C, units u1 to u3 similar to those in region 200A are arranged along the same direction 201, but the arrangement of arrays 202 to 204 differs from that in region 200A. For example, in regions 200A to 200C, the order in which arrays 202 to 204 are arranged in a direction perpendicular to direction 201 in which the units are arranged is the same. On the other hand, the longest array in direction 201 in which the units are arranged is array 204 in region 200A, whereas it is array 203 in region 200B and array 202 in region 200C.
[0110] 8B, the conductor pattern according to the first modified example has regions 220A to 220C. In region 220A, units u1 to u3 are arranged along direction 221. In regions 220B and 220C, units u1 to u3 similar to those in region 220A are arranged along the same direction 221, but the arrangement of arrays 222 to 224 differs from that in region 220A.
[0111] In the example shown in FIGS. 8A and 8B, the regions 200A to 200C and the regions 220A to 220C are shown adjacent to each other, but the arrangement of the regions 200A to 200C and the regions 220A to 220C is not limited to this.
[0112] An example of a conductor pattern according to a first modification is shown in 9A of Fig. 9. Conductor pattern 1400 shown in 9A of Fig. 9 includes rows 1410 to 1460 arranged side by side in the Y-axis direction. Note that rows 1410 to 1460 may be arranged below row 1460 in the Y-axis direction. In other words, rows 1410 to 1460 may be arranged in plurality at equal intervals in the Y-axis direction.
[0113] In row 1410, the regions are arranged in the X-axis direction in the order of regions 200A, 220A, 200B, 220B, 200C, and 220C described with reference to FIGS. 8A and 8B.
[0114] In row 1420, the regions are arranged in the order of regions 230A, 210B, 230B, 210C, 230C, and 210A in the X-axis direction. Here, region 210A is a region in which the direction 201 in which units are arranged in region 200A has been changed to direction 211. Similarly, regions 210B and 210C are regions in which the direction 201 in which units are arranged in region 200B and 200C, respectively, has been changed to direction 211. Similarly, regions 230A, 230B, and 230C are regions in which the direction 221 in which units are arranged in region 220A to 220C, respectively, has been changed to direction 231.
[0115] The regions 210A to 210C may differ from each other in at least one of the shape, size, and spacing of the units u1 to u3 included in the regions, and the spacing between the arrays.
[0116] Furthermore, the regions 230A to 230C may differ from one another in at least one of the shape, size, and spacing of the units u1 to u3 included in the regions, and the spacing between the arrays.
[0117] In row 1430, the regions are arranged in the X-axis direction in the following order: regions 200B, 220B, 200C, 220C, 200A, 220A. In row 1440, the regions are arranged in the X-axis direction in the following order: regions 230B, 210C, 230C, 210A, 230A, 220B. In row 1450, the regions are arranged in the X-axis direction in the following order: regions 200C, 220C, 200A, 220A, 200B, 220B. In row 1460, the regions are arranged in the X-axis direction in the following order: regions 230C, 210A, 230A, 210B, 230B, 210C.
[0118] As described above, regions 200A-200C and 210A-210C have different electromagnetic wave transmission characteristics from regions 220A-220C and 230A-230C. Therefore, by arranging regions with different electromagnetic wave transmission characteristics adjacent to each other, it is possible to maintain good electromagnetic wave transmission characteristics when viewed as a whole of conductor pattern 1400. Furthermore, as shown in rows 1410-1460, the regions are arranged so that the direction in which units u1-u3 are arranged in the Y direction differs between adjacent regions. This allows the entire conductor pattern 1400 to maintain good electromagnetic wave absorption characteristics depending on the polarization direction of the incident electromagnetic wave.
[0119] [Second Modification] In the examples of 6A in Fig. 6 and 9A in Fig. 9, the units u1 to u3 are arranged in the same direction in two regions adjacent to each other in the X direction. In one example, the regions may be arranged such that the units u1 to u3 are arranged in different directions in regions adjacent to each other in the X and Y directions.
[0120] Figure 9B shows a conductor pattern 1500 according to a second modification. In Figure 9B, regions similar to regions 200A to 230C in Figure 9A are arranged in a different pattern. The conductor pattern 1500 includes rows 1510 to 1560.
[0121] In row 1510, regions 200A, 210A, 220B, 230B, 200C, and 210C are arranged side by side in the X direction. In row 1520, regions 230A, 220A, 210B, 200B, 230C, and 220C are arranged side by side in the X direction. In row 1530, regions 200B, 210B, 220C, 230C, 200A, and 210A are arranged side by side in the X direction. In row 1540, regions 230B, 220B, 210C, 200C, 230A, and 220A are arranged side by side in the X direction. In row 1550, regions 200C, 210C, 220A, 230A, 200B, and 210B are arranged side by side in the X direction. In row 1560, regions 230C, 220C, 210A, 200A, 230B, and 220B are arranged side by side in the X direction.
[0122] In this way, the regions are arranged so that the directions in which the units u1 to u3 are arranged are different in adjacent regions in both the X and Y directions. This allows the electromagnetic wave absorption characteristics depending on the polarization direction of the incident electromagnetic waves to be maintained favorably throughout the conductor pattern 1500. Furthermore, by arranging two regions with different electromagnetic wave transmission characteristics in the X direction and one region in the Y direction, the electromagnetic wave transmission characteristics can be maintained favorably when viewed as a whole of the conductor pattern 1500.
[0123] The area arrangement pattern is not limited to this, as long as the areas are arranged so that the directions in which the units are arranged differ between adjacent areas in the X and Y directions.
[0124] Other Embodiments The invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the gist of the invention.
[0125] In the examples of Figures 2, 5, 6A, and 9, the first to third units are arranged in one region. In one example, two units may be arranged in one region, or four or more types of units may be arranged in one region. That is, the electromagnetic wave absorbing member may have two or more regions including a first region including one or more first arrays in which first units are arranged in a first direction and a second array in which second units different from the first units are arranged in the first direction, and a second region including one or more third and fourth arrays in which the first and second units are arranged in a second direction different from the first direction, and the number of arrays and the number of regions can be changed as appropriate.
[0126] In addition, although the present embodiment has been described assuming that the region is rectangular, the shape of the region is not limited to a rectangle, and may be a quadrangle including a parallelogram, a triangle, a hexagon, or a polygon.
[0127] In the examples of Figures 2, 5, 6A, and 9, the two arrays are shown as being arranged so as not to overlap in the direction in which the units are arranged. However, multiple arrays may be arranged so as to overlap in the direction in which the units are arranged. For example, an array in which three units u1 are arranged in the direction along the arrow 201, followed by an array in which three units u2 are arranged, may be arranged.
[0128] In 6A of FIG. 6, the units are arranged in two directions. However, the units may be arranged in three or more directions. For example, the area may be designed so that the units are arranged in four directions, such as 0 degrees, 30 degrees, 60 degrees, and 90 degrees.
[0129] REFERENCE SIGNS LIST 1 electromagnetic wave absorbing member 10 resistive layer 11 substrate 12 conductive pattern 20 spacer layer 30 reflective layer 200 first region 250 second region 210, 260 first arrangement 220, 270 second arrangement 230, 280 third arrangement
Claims
1. It has a resistive layer with a conductive pattern, The resistive layer has first and second regions that have different electromagnetic wave transmission characteristics from each other. The first region is, It has multiple first arrangements in which multiple first units are arranged, It has multiple second arrangements, each in which multiple second units, different from the first unit, are arranged. Having a conductive pattern, The aforementioned second region is, Having multiple of the above-mentioned first sequences, Having multiple of the aforementioned second sequences, Having a conductive pattern, In the first region, the first unit and the second unit are arranged in a plurality in the first direction. In the second region, the first and second units are arranged in a second direction different from the first direction. An electromagnetic wave absorbing member characterized in that, in the first region and the second region, the first arrangement and the second arrangement are arranged adjacent to each other.
2. The first region has multiple third arrangements, each in which multiple third units, which are different from both the first and second units, are arranged. The second region has a plurality of the third arrangements, In the first region, the third unit is arranged in the first direction. The electromagnetic wave absorbing member according to claim 1, wherein the third unit is arranged in the second direction within the second region.
3. The electromagnetic wave absorbing member according to claim 1, wherein the conductive pattern of the second region is a pattern obtained by rotating and inverting at least one of the conductive patterns of the first region.
4. The electromagnetic wave absorbing member according to claim 1, wherein the first region and the second region are repeatedly arranged at regular intervals.
5. The resistive layer further comprises a third region and a fourth region having different electromagnetic wave transmission characteristics from each other. The third region described above is, The array has multiple arrangements in which the fourth unit is arranged in the first direction, The array has multiple arrangements in which a fifth unit, different from the fourth unit, is arranged in the first direction. Having a conductive pattern, The fourth region is, The array has multiple arrangements in which the fourth unit is arranged in the second direction, The array has multiple arrangements in which the fifth unit is arranged in the second direction. Having a conductive pattern, The first region and the third region differ in at least one of the following: the spacing of the conductive pattern array, the shape of the units included in the array, the dimensions of the units, and the spacing of the units. The electromagnetic wave absorbing member according to claim 1, wherein the second region and the fourth region differ in at least one of the spacing of the arrangement of conductive patterns, the shape of the units included in the arrangement, the dimensions of the units, and the spacing of the units.
6. The third region has multiple arrays in which a sixth unit, different from both the fourth unit and the fifth unit, is arranged in the first direction. The electromagnetic wave absorbing member according to claim 5, wherein the fourth region has a plurality of arrangements in which the sixth unit is arranged in the second direction.
7. The electromagnetic wave absorbing member according to claim 5, wherein the third region and the fourth region are repeatedly arranged at regular intervals.
8. The electromagnetic wave absorbing member according to claim 5, wherein the conductive pattern of the fourth region is a pattern obtained by rotating and inverting at least one of the conductive patterns of the third region.
9. The electromagnetic wave absorbing member according to claim 5, wherein the first region is arranged to be adjacent to at least one of the third region and the fourth region, but not adjacent to the second region.
10. The electromagnetic wave absorbing member according to claim 5, wherein the first region is arranged to be adjacent to at least one of the second region and the fourth region, but not adjacent to the third region.
11. It has a fifth region having a conductive pattern having a plurality of the first arrangements and a plurality of the second arrangements, In the fifth region described above, The first unit and the second unit are arranged in a third direction different from both the first and second directions. The first array and the second array are arranged adjacent to each other. The electromagnetic wave absorbing member according to claim 1.
12. An electromagnetic wave absorbing member according to any one of claims 1 to 11, further comprising a spacer layer and a reflective layer.