Radio-wave-transmitting body and window material

Abstract

The present invention enhances the radio wave transmissivity of a window material. Provided is a translucent radio-wave-transmitting body 4 disposed on the surface of a window material 1 comprising a transparent plate 2 and a metal layer 3 laminated on the transparent plate. The radio-wave-transmitting body comprises a conductive layer 41 and a substrate layer 43 supporting the conductive layer. The conductive layer 41 is such that a plurality of areas 42, which are surrounded by the conductive layer 41 and in which the conductive layer is absent, are periodically arranged both vertically and horizontally, spaced apart by a spacing GAP. Each area 42 is defined by the length of a line segment PA that passes through the center of gravity CG of the area 42 and connects two ends of the area 42. The length of the line segment PA is the distance between the centers of gravity CG of adjacent areas 42, 42 minus the spacing GAP between the areas 42, 42. The combination of the line segment PA and the spacing GAP is the combination of the line segment PA being between 5.3 mm and 21.1 mm, inclusive, and the spacing GAP being between 0.3 mm and 15 mm, inclusive, or the combination of the line segment PA being 31.6 mm and the spacing GAP being between 3 mm and 7 mm, inclusive. The transmitted radio wave strength is greater than 0 dB for incident radio waves with frequencies from 3.5 GHz to 4.7 GHz.

Description

Radio wave transmitting body and window material

[0001] The present invention relates to a radio wave transmitting body that is placed on the surface of a window material, and to a window material that includes a radio wave transmitting body.

[0002] In recent years, window glass (hereinafter referred to as window material) with excellent heat blocking properties in summer and heat insulating properties in winter has become increasingly popular as an energy-saving measure for buildings. In such window materials, a Low-E film is formed on the entire surface of one of the surfaces that constitutes the window material.

[0003] On the other hand, it is known that when a Low-E film is formed on a window material, the transmittance of radio waves decreases over a wide frequency band. The occurrence of radio wave blind zones inside a building is a problem for the widespread use of high-speed wireless communications, such as 5G, that make up mobile phone networks. Therefore, in conventional window materials, as in Patent Document 1, for example, a radio wave transmittance area is formed by removing a portion of the Low-E film using laser processing, thereby improving the indoor radio wave communication environment.

[0004] JP 2023-113772 A

[0005] However, when manufacturing a window material, removing a portion of the Low-E film as in Patent Document 1 cannot be said to be efficient for production. Moreover, it is not realistic to perform such a Low-E film removal process on window materials that have already been installed in buildings. There is a need for a technology that can easily increase the radio wave transmittance of window materials.

[0006] An object of the present invention is to provide a technique for easily increasing the radio wave transmittance of a window material.

[0007] To achieve the above object, the present invention includes the following subject matter. (Item 1) A light-transmitting radio wave transmitting body disposed on the surface of a window material comprising at least one transparent plate and a metal layer laminated on the at least one transparent plate, the body comprising: a conductive layer; and a base layer supporting the conductive layer; wherein the conductive layer has a plurality of conductive layer-free regions surrounded by the conductive layer, the conductive layer being periodically arranged vertically and horizontally at a predetermined interval, the conductive layer having a plurality of conductive layer-free regions surrounded by the conductive layer, the conductive layer being a region defined by the length of a line segment passing through the center of gravity of the region and connecting both ends of the region, the length of the line segment being the distance between the centers of gravity of adjacent regions minus the interval; and wherein the combination of the length of the line segment and the length of the interval is: the length of the line segment is 5.3 mm or more and 21.1 mm or less, and the length of the interval is 0.3 mm or more and 15 mm or less, or the length of the line segment is 31.6 mm, and the length of the interval is 3 mm or more and 7 mm or less; and wherein the radio wave intensity after transmission of incident radio waves having a frequency of 3.5 GHz to 4.7 GHz is greater than 0 dB. (Item 2) The radio wave transmission body according to Item 1, wherein the region without the conductive layer is a rectangle surrounded by one or more linear conductive layers. (Item 3) The radio wave transmission body according to Item 2, wherein a combination of the length of the line segment and the length of the gap is: a combination in which the length of the line segment is 5.3 mm or more and 21.1 mm or less and the length of the gap is 0.2 mm or more and 15 mm or less, or a combination in which the length of the line segment is 31.6 mm and the length of the gap is 3 mm or more and 5 mm or less, and the radio wave intensity after transmission is 4 dB or more. (Item 4) A window material comprising: at least one transparent plate; a metal layer laminated on the at least one transparent plate; and the radio wave transmission body according to any one of Items 1 to 3 attached to the transparent plate or the metal layer.

[0008] According to the present invention, a technique for easily increasing the radio wave transmittance of a window material can be provided.

[0009] FIG. 1 is a cross-sectional view of a window material according to an embodiment. FIG. 2 is a diagram showing a schematic configuration of the entire radio wave transmitting body according to an embodiment. (A) is a plan view, and (B) is an enlarged view of part A in (A). FIG. 1 is a cross-sectional view of a radio wave transmitting body according to an embodiment. FIG. 2 is a diagram for explaining another example of the pattern of a conductive layer provided on a radio wave transmitting body. FIG. 3 is a cross-sectional view of a window material according to modified example 1. FIG. 4 is a cross-sectional view of a window material according to modified example 2. FIG. 5 is a waveguide model used in a numerical simulation according to an example. FIG. 6 is a pattern of a conductive layer used in a numerical simulation according to an example. FIG. 7 is a scatter plot for explaining the results of a numerical simulation according to an example.

[0010] Embodiments of the present invention will now be described with reference to the drawings. A window material 1 according to this embodiment has a light-transmitting radio wave transmitting body 4 disposed on its surface. Although the window material 1 according to this embodiment has reduced radio wave transmittance over a wide frequency band due to the inclusion of the metal layer 3, the radio wave transmittance body 4, which is a metasurface film, disposed on the surface improves radio wave transmittance.

[0011] First, the window material 1 on which the radio wave transmitting body 4 is disposed will be described below. Next, each component of the window material 1, including the radio wave transmitting body 4, will be described.

[0012] (Window Material) As shown in Fig. 1 , the window material 1 is a double glazing having a plurality of transparent plates 2. The window material 1 includes the plurality of transparent plates 2, a metal layer 3, and a radio wave transmitting body 4. The window material 1 also includes a spacer 5 that maintains a distance between the plurality of transparent plates 2.

[0013] As shown in FIGS. 2 and 3, the radio wave transmitting body 4 includes a base layer 43 attached to the transparent plate 2 or the metal layer 3, and a conductive layer 41 formed on the base layer 43.

[0014] Because the window material 1 according to this embodiment is configured in this manner, it is possible to increase the radio wave transmittance only for radio waves in a specific frequency band, even if the metal layer 3 reflects or blocks radio waves. Moreover, because it is only necessary to attach the radio wave transmitting body 4 to the window material 1 on which the existing metal layer 3 is laminated, the window material 1 can be made highly manufacturable.

[0015] The window material 1 according to this embodiment is used, for example, as window glass in buildings, as well as light-receiving windows in doors, fixed windows in ceilings, floors, etc. Furthermore, the window material 1 according to this embodiment can also be used for windows in automobiles, aircraft, ships, trains, ropeways, etc. in addition to buildings.

[0016] In the window material 1, the specific frequency band of radio waves that can enhance the radio wave transmittance is preferably any radio wave in the range of 0.5 GHz to 60 GHz. In this embodiment, the transparent plate 2 is configured to enhance the radio wave transmittance in the 5 GHz frequency band (3 GHz to 5 GHz, 25 GHz to 30 GHz). However, there are no particular restrictions on the frequency band in which the radio wave transmittance of the window material 1 is to be enhanced. The specific frequency band in which the radio wave transmittance is to be enhanced can be set to a desired frequency band by changing the shape of the conductive layer 41 in the radio wave transmitting body 4.

[0017] (Transparent Plate 2) The transparent plate 2 is a transparent plate material. In this specification, "transparent" means that the light transmittance is 10% or more with respect to the peak wavelength of the light before incidence, preferably 50% or more, and more preferably 80% or more. In other words, "transparent" in this specification also includes "semi-transparent" in which the light transmittance is, for example, about 30% with respect to the peak wavelength of the light before incidence. Furthermore, the transparent plate 2 is not limited to being colorless and transparent, and may be colored.

[0018] The transparent plate 2 according to the present embodiment is preferably a glass plate. Examples of the glass plate include float glass, figured glass, frosted glass, wired glass, and tempered glass. However, examples of the transparent plate 2 include an acrylic plate and a polycarbonate plate in addition to a glass plate.

[0019] There are no particular limitations on the shape of the transparent plate 2. The shape of the transparent plate 2 may be, for example, a rectangular shape in a plan view, a circular shape in a plan view, a pentagonal shape in a plan view, a hexagonal shape in a plan view, an elliptical shape in a plan view, etc. Here, "plan view" means that the main surface of the transparent plate 2 is viewed from a direction perpendicular to the main surface.

[0020] 1, the multiple transparent plates 2 are arranged at regular intervals in the thickness direction of the window material 1. Of the adjacent transparent plates 2, one transparent plate 2 may be referred to as the "first transparent plate 21" and the other transparent plate 2 may be referred to as the "second transparent plate 22."

[0021] A spacer 5 is disposed between the first transparent plate 21 and the second transparent plate 22. The spacer 5 maintains the distance between the two adjacent transparent plates 21, 22. The outer peripheries of the transparent plates 2 are surrounded by a sealing material (not shown), and the space (intermediate layer 6) between the two adjacent transparent plates 21, 22 is formed airtight. The intermediate layer 6 is preferably filled with an insulating gas. Examples of the insulating gas include an inert gas such as argon gas. However, the intermediate layer 6 may also be filled with air. Alternatively, the intermediate layer 6 may be a vacuum.

[0022] The first transparent plate 21 has a first surface 211 and a second surface 212. Similarly, the second transparent plate 22 has a first surface 221 and a second surface 222. The first surfaces 211 and 221 are one of the surfaces (main surfaces) in the thickness direction of the transparent plate 2. The second surfaces 212 and 222 are main surfaces opposite the first surfaces 211 and 221. In this embodiment, the first surfaces 211 and 221 refer to surfaces of adjacent transparent plates 2 that face each other (inner surfaces in the thickness direction of the window material 1), and the second surfaces 212 and 222 refer to outer surfaces of the window material 1.

[0023] The window material 1 in this embodiment is a double-pane glass made up of two transparent plates 2, but it may also be a triple-pane glass made up of three transparent plates 2, or it may be made up of four or more transparent plates 2.

[0024] (Metal Layer 3) The metal layer 3 is laminated on the transparent plate 2 to improve the heat insulating properties of the window material 1. The metal layer 3 is preferably a Low-E film. There are no particular limitations on the Low-E film, and examples thereof include a film in which a transparent dielectric layer, an infrared reflective layer, and a transparent dielectric layer are laminated in this order. Examples of the transparent dielectric layer include metal oxides (e.g., zinc oxide, tin oxide) and metal nitrides. Examples of the infrared reflective layer include metal films (e.g., silver), semiconductor films, etc.

[0025] The metal layer 3 may be laminated on any one of the plurality of transparent plates 2. In this embodiment, the metal layer 3 is laminated on the first surface 211 of the first transparent plate 21. The metal layer 3 is laminated over the entire surface of the first surface 211 of the transparent plate 2. The metal layer 3 is laminated on the transparent plate 2 by, for example, coating, vapor deposition, adhesion, welding, or the like.

[0026] (Radio wave transmitting body 4) The radio wave transmitting body 4 is attached to the transparent plate 2 or the metal layer 3. By attaching the radio wave transmitting body 4 to the transparent plate 2 or the metal layer 3, it is possible to increase the radio wave transmittance of the window material 1 in a specific frequency band of radio waves. As shown in Figures 2 and 3, the radio wave transmitting body 4 has a base layer 43, a conductive layer 41, and a protective film 45 laminated in this order. The radio wave transmitting body 4 according to this embodiment is attached to the second surface 212 of the first transparent plate 21. The radio wave transmitting body 4 may cover the entire surface of the transparent plate 2, or may be attached to only a part of the entire surface.

[0027] (Substrate Layer 43) The substrate layer 43 supports the conductive layer 41. In this embodiment, the substrate layer 43 is transparent. The substrate layer 43 is attached to the transparent plate 2 or the metal layer 3. An adhesive layer (hereinafter referred to as the first adhesive layer 46) is provided on the surface of the substrate layer 43 opposite the conductive layer 41. The first adhesive layer 46 preferably has a large number of capsules filled with adhesive before bonding, and is structured so that the adhesive ruptures when pressure is applied from the substrate layer 43 toward the transparent plate 2 or the metal layer 3 during bonding, thereby enabling bonding. However, the first adhesive layer 46 may also be an adhesive applied without being filled into capsules. Examples of adhesives include synthetic resins such as acrylic resin, silicone resin, and polyvinyl alcohol resin.

[0028] In this embodiment, the outer shape of the base material layer 43 is quadrangular (more specifically, square) in plan view, as shown in Fig. 2. However, there are no particular limitations on the shape of the base material layer 43, and examples thereof include a polygon, a circle, an ellipse, a star, a heart, and the like. The thickness of the base material layer 43 is uniform over the entire surface. However, the thickness of the base material layer 43 does not have to be uniform.

[0029] Examples of the substrate layer 43 include synthetic resin, fiber reinforced plastics (FRP), carbon, and glass. Examples of the synthetic resin include one or more selected from the group consisting of PET (polyethylene terephthalate), 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. The substrate layer 43 may be a composite material of these synthetic resins. The substrate layer 43 according to this embodiment is made of a PET film.

[0030] The thickness of the base layer 43 is, for example, preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 20 μm or more. On the other hand, the upper limit of the thickness of the base layer 43 is, for example, preferably 500 μm or less, more preferably 130 μm or less, and even more preferably 100 μm or less.

[0031] The base layer 43 preferably has flexibility. The modulus of longitudinal elasticity of the base layer 43 is, for example, preferably 0.01 GPa or more, more preferably 1 GPa or more, and even more preferably 8 GPa or more. On the other hand, the upper limit of the modulus of longitudinal elasticity of the base layer 43 is, for example, preferably 80 GPa or less, more preferably 30 GPa or less, and even more preferably 20 GPa or less.

[0032] (Conductive layer 41) The conductive layer is a metal microstructure having a structure finer than the wavelength of the target radio wave (electromagnetic wave). The conductive layer corresponds to a split ring resonator in a metasurface (metamaterial) and is also called a split ring resonator (SRR). In this specification, the conductive layer may be referred to as a "split ring resonator portion."

[0033] The conductive layer 41 includes a conductor and constitutes a transmission surface. The conductive layer 41 is formed on a base layer 43. Methods for forming the conductive layer 41 on the base layer 43 include, for example, laminating a thin film formed by embedding the conductive layer 41 in a thin-film dielectric on the base layer 43, or forming the conductive layer 41 on the base layer 43 without using a dielectric.

[0034] Examples of the conductor constituting the conductive layer 41 include one or more of silver, gold, copper, platinum, aluminum, titanium, silicone, indium tin oxide, and alloys (e.g., alloys containing nickel, chromium, and molybdenum). 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.

[0035] The thickness of the conductive layer 41 is preferably 10 nm or more, more preferably 30 nm or more, and even more preferably 100 nm or more. On the other hand, the upper limit of the thickness of the conductive layer 41 is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 4 μm or less. When the thickness of the conductive layer 41 is 10 nm or more, appropriate radio wave intensity can be ensured.

[0036] The conductive layer 41 preferably has a relative dielectric constant of 7 or more. On the other hand, the upper limit of the relative dielectric constant is preferably 10,000 or less.

[0037] (Pattern of Conductive Layer 41) The conductive layers 41 are arranged in a planar pattern, for example, as shown in FIG. 2B . In this embodiment, linear conductive layers 41 are arranged at equal intervals along the vertical and horizontal directions, and a region 42 (non-conductive region 42) without a conductive layer is surrounded by one or more linear conductive layers 41. In this embodiment, the region 42 without a conductive layer is rectangular (square), and multiple regions are periodically arranged at intervals equal to the line width L6 of the conductive layer 41. At the intersections where a conductive layer 41 (41A) extending along the horizontal direction overlaps a conductive layer 41 (41B) extending along the vertical direction, the conductive layers 41A and 41B are electrically connected. The length L7 between adjacent conductive layers 41 along the vertical or horizontal direction (the length of one side of the square region 42 without a conductive layer) is set to be greater than the wavelength of visible light and smaller than the wavelength of radio waves passing through the radio wave transmitting body 4. The area 42 without the conductive layer may be filled with adhesive of the adhesive layer 44 .

[0038] 4 is a diagram illustrating another example of the pattern of the conductive layer 41 provided on the radio wave transmitting body 4. In this embodiment, the pattern of the region 42 without a conductive layer is rectangular (square) in plan view, but the pattern of the region 42 is not limited to a rectangle. The pattern of the region 42 without a conductive layer can be a pattern that satisfies the conditions described below.

[0039] That is, in a pattern in which a plurality of regions 42 without a conductive layer are surrounded by a conductive layer 41 and periodically arranged vertically and horizontally at predetermined intervals, the region 42 is defined by the length of a line segment that passes through the center of gravity of the region 42 and connects both ends of the region 42. The length of this line segment is the distance between the centers of gravity of adjacent regions 42 minus the spacing between the multiple regions 42. As shown below for several shapes as examples, the region 42 without a conductive layer can be defined by the length of such a line segment that passes through the center of gravity of the region 42 and connects both ends of the region 42.

[0040] 4A shows an example in which the conductive layer-free region 42 is circular. In the example shown in FIG. 4A, the conductive layer-free region 42 is defined by the line segment a １ b １ The length of the line segment a １ b １is the center of gravity C of the region 42 １ The length of the line segment a1b1 is the distance from the center of gravity C of the adjacent region 42. １ , C ２ From the distance between the adjacent regions 42 (line segment b １ a ２ The length is the length minus the length of the

[0041] In the example of the circle shown in FIG. 4A, the area 42 without the conductive layer is defined by the line segment a １ b １ Instead of the length of the line segment d １ e １ It can also be defined by the length of the line segment d １ e １ is the center of gravity C of the region 42 １ The line segment d passes through and connects both ends of the region 42. １ e １ The length of the center of gravity C of the adjacent region 42 １ , C ３ From the distance between the adjacent regions 42 (line segment e １ d ３ The length is the length minus the length of the

[0042] 4B shows an example in which the region 42 without a conductive layer is a regular pentagon. In the example shown in FIG. 4B, the region 42 without a conductive layer is defined by a line segment a １ b １ As in FIG. 4A, the length of the line segment a １ b １ is the center of gravity C of the region 42 １ The line segment a passes through and connects both ends of the region 42. １ b １ The length of the center of gravity C of the adjacent region 42 １ , C ２ From the distance between the adjacent regions 42 (line segment b １ a ２ The length is the length minus the length of the

[0043] In the example of a regular pentagon shown in FIG. 4B, the area 42 without a conductive layer is defined by the line segment a １ b １ Instead of the length of the line segment d １ e １It can also be defined by the length of the line segment d １ e １ is the center of gravity C of the region 42 １ The line segment d passes through and connects both ends of the region 42. １ e １ The length of the center of gravity C of the adjacent region 42 １ , C ３ From the distance between the adjacent regions 42 (line segment e １ d ３ The length is the length minus the length of the

[0044] (Protective Film 45) The protective film 45 can protect the conductive layer 41 by covering the conductive layer 41. The protective film 45 has a size corresponding to the base material layer 43 in a plan view. Examples of the protective film 45 include films made of synthetic resins. Examples of synthetic resins include one or more selected from the group consisting of PET (polyethylene terephthalate), COP (cycloolefin polymer), 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 protective film 45 preferably contains fluorine. The protective film 45 containing fluorine can prevent transmission of ultraviolet rays, and therefore can protect the conductive layer 41 from ultraviolet rays.

[0046] The thickness of the protective film 45 is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 15 μm or more. On the other hand, the upper limit of the thickness of the protective film 45 is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 25 μm or less.

[0047] The protective film 45 is adhered to the base layer 43 via an adhesive layer (hereinafter referred to as the second adhesive layer 44). Examples of the second adhesive layer 44 include a synthetic resin, a rubber adhesive sheet, etc. Examples of the synthetic resin include an acrylic resin, a silicone resin, and a polyvinyl alcohol resin.

[0048] <Modifications> The above embodiment is merely one of various embodiments of the present invention. The embodiment can be modified in various ways depending on the design, etc., as long as the object of the present invention can be achieved. Modifications of the embodiment are listed below. The modifications described below can be applied in appropriate combinations.

[0049] (Variation 1) In the above embodiment, the window material 1 has multiple transparent plates 2, but as shown in Fig. 5, the window material 1 may have only one transparent plate 2. As shown in Fig. 5, a metal layer 3 is laminated on a first surface 211 of the transparent plate 2. A radio wave transmitting body 4 is attached to the metal layer 3. Note that the radio wave transmitting body 4 may also be attached to a second surface 212 on which no metal layer 3 is provided.

[0050] Furthermore, the metal layer 3 is not limited to a Low-E film and may be a heat-shielding film. When the metal layer 3 is a heat-shielding film, it may be attached to the first surface 211 or the second surface 212 of the transparent plate 2, for example, after the window material 1 is installed in the window frame.

[0051] (Variant 2) In the above embodiment, the radio wave transparent body 4 was attached to a transparent plate 2 (first transparent plate 21) on which the metal layer 3 was laminated, but as shown in Figure 6, the radio wave transparent body 4 may also be attached to a transparent plate 2 (second transparent plate 22) other than the transparent plate 2 on which the metal layer 3 was laminated.

[0052] The distance between the radio wave transmitting body 4 and the metal layer 3 is preferably 110 mm or less, more preferably 30 mm or less, and even more preferably 10 mm or less. On the other hand, the lower limit of the distance between the radio wave transmitting body 4 and the metal layer 3 may be 0 mm. In other words, the radio wave transmitting body 4 may be directly bonded to the metal layer 3 (see FIG. 5 ).

[0053] Example In this example, the degree to which radio wave transmission is improved by placing a radio wave transmitting body on the surface of a window material was confirmed by numerical simulation. The numerical simulation was performed based on the waveguide model 9 shown in Fig. 7. For the radio wave transmitting body included in the illustrated waveguide model 9, the conductive layer pattern (i.e., the metastructure conditions) shown in Fig. 8 was specified, and the intensity of radio waves transmitted through the window material was calculated for this specified waveguide model 9.

[0054] The line segment PA and the gap GAP shown in FIG. 8 were defined as variables defining the pattern of the conductive layer of the radio wave transmitting body. The radio wave intensity transmitted through the window material was calculated by comprehensively combining the multiple conditions (numerical ranges) shown in Table 1 and comprehensively varying the dimensions of these defined variables PA and GAP within the numerical ranges shown in Table 1. In this example, the radio wave intensity transmitted through the window material was calculated for a total of 281 conditions, including 253 combinations of the 11 variables PA and 23 variables GAP shown in the upper part of Table 1, plus 28 combinations of the variables PA and GAP shown in the lower part of Table 1. In this example, the frequencies of the radio waves incident on the window material were 3.5 GHz, 3.7 GHz, 4.5 GHz, and 4.7 GHz. Comprehensive numerical simulations were performed for each of these four frequencies, varying the conditions across the 281 conditions described above. The strength of the incident radio waves was calculated by multiplying the strength of the radio waves transmitted through the window material (Low-E) by -60.9578 dB (minus 60.9578 dB). The results of the numerical simulation are shown in Figure 9. When considering the results, it was determined that radio wave transmission was improved when the radio wave strength after transmission was greater than 0 dB for the incident radio waves.

[0055]

[0056] To facilitate understanding of the example, the same reference numerals are used in Figures 7 and 8 to designate the same components as those described in the above embodiment. Line segment PA corresponds to the line segment that passes through the center of gravity of region 42 without a conductive layer and connects both ends of region 42, as described with reference to Figure 4. Symbol CG indicates the center of gravity of region 42 without a conductive layer. Gap corresponds to the gap between adjacent regions 42 without a conductive layer, as described with reference to Figure 4.

[0057] The scatter diagram in FIG. 9 plots combinations of the PA and GAP variables for which the intensity of the radio waves transmitted through the window material was greater than 0 dB over the frequency range of 3.5 GHz to 4.7 GHz of the incident radio waves, as determined by numerical simulation.

[0058] FIG. 9A shows a combination of dimensions for which the radio wave intensity is greater than 0 dB and less than 4 dB, and a combination of dimensions for which the radio wave intensity is 4 dB or greater.

[0059] Figure 9(B) shows the combinations of dimensions that result in radio wave intensity greater than 0 dB and less than 4 dB. As shown in Figure 9(B), numerical simulations have shown that when the combination of dimensions of the line segment PA and the gap GAP is either the first or second combination shown below, radio waves penetrate with an intensity greater than 0 dB and less than 4 dB. In the first combination, the line segment PA is 5.3 mm or more and 21.1 mm or less, and the gap GAP is 0.3 mm or more and 15 mm or less. In the second combination, the line segment PA is 31.6 mm, and the gap GAP is 3 mm or more and 7 mm or less.

[0060] Figure 9(C) shows the combinations of dimensions that result in radio wave intensity of 4 dB or more. As shown in Figure 9(C), numerical simulations have shown that when the combination of dimensions of the line segment PA and the gap GAP is either the third or fourth combination shown below, radio waves penetrate with an intensity of 4 dB or more. In the third combination, the line segment PA is 5.3 mm or more and 21.1 mm or less, and the gap GAP is 0.2 mm or more and 15 mm or less. In the fourth combination, the line segment PA is 31.6 mm, and the gap GAP is 3 mm or more and 5 mm or less.

[0061] REFERENCE SIGNS LIST 1 window material 2 transparent plate 21 first transparent plate 211 first surface 212 second surface 22 second transparent plate 221 first surface 222 second surface 3 metal layer 4 radio wave transparent body (metasurface film) 41 conductive layer 42 non-conductive region 43 substrate layer 44 adhesive layer 45 protective film

Claims

1. A light-transmitting radio wave transmitting body arranged on the surface of a window material comprising at least one transparent plate and a metal layer laminated on said at least one transparent plate, said body comprising: a conductive layer; and a base layer supporting said conductive layer; wherein said conductive layer has a plurality of regions without conductive layer surrounded by said conductive layer, which are periodically arranged lengthwise and widthwise at predetermined intervals; wherein said regions without conductive layer are regions defined by the length of a line segment passing through the center of gravity of said region and connecting both ends of said region, said length of said line segment being the distance between the centers of gravity of said adjacent regions minus said interval; and wherein the combination of the length of said line segment and the length of said interval is: a combination in which the length of said line segment is 5.3 mm or more and 21.1 mm or less, and the length of said interval is 0.3 mm or more and 15 mm or less, or a combination in which the length of said line segment is 31.6 mm, and the length of said interval is 3 mm or more and 7 mm or less; and wherein the radio wave intensity after transmission of incident radio waves with a frequency of 3.5 GHz to 4.7 GHz is greater than 0 dB.

2. The radio wave transparent body according to claim 1, wherein the region without the conductive layer is a rectangle surrounded by one or more linear conductive layers.

3. The radio wave transmitting body according to claim 2, wherein the combination of the length of the line segment and the length of the gap is: the length of the line segment is 5.3 mm or more and 21.1 mm or less, and the length of the gap is 0.2 mm or more and 15 mm or less; or the length of the line segment is 31.6 mm, and the length of the gap is 3 mm or more and 5 mm or less; and the radio wave intensity after transmission is 4 dB or more.

4. A window material comprising: at least one transparent plate; a metal layer laminated on said at least one transparent plate; and a radio wave transparent body according to any one of claims 1 to 3 attached to said transparent plate or said metal layer.

Images