Window and manufacturing method therefor

Abstract

This window comprises: a multilayered glass that has glass sheets arranged facing each other with an interval therebetween, and a hollow layer formed between these glass sheets; and a frame that holds the peripheral edge of this multilayered glass, wherein in a target communication frequency band that is included in the frequency band 24-300 GHz, the window has a continuous frequency range in which the radio wave reflection rate is 50% or less, the dn∙√εn / λ values of each of the glass sheets and the hollow layer satisfy expression (1), and the total d∙√ε / λ value of the dn∙√εn / λ values satisfies expression (2). This window has good radio wave permeability throughout the entire frequency range of the millimeter wave band.　(1): 0.5Nn–0.1≤dn∙√εn / λ≤ 0.5Nn+0.1 (dn is the thickness (mm) of the respective layer, εn is the relative permittivity of the respective layer at an intermediate frequency of the target communication frequency band, λ is the radio wave wavelength (mm) at the intermediate frequency, N is a natural number from 1 to 100, and n is the number of the respective layer.)　(2): 0.5N–0.2≤d∙√ε / λ≤0.5N+0.2

Description

Window and its manufacturing method

[0001] The present invention relates to a window and a manufacturing method thereof, and more particularly to a window having good transmission characteristics for millimeter-wave band waves and a manufacturing method thereof.

[0002] In recent years, with the expansion of high-speed, high-capacity communication infrastructure, such as fifth-generation mobile communication systems (hereinafter referred to as "5G"), high-frequency waves, such as the millimeter wave band (30-300 GHz), which have not previously been used in general mobile communication networks, have begun to be fully utilized. However, millimeter wave radio waves have a strong tendency to propagate in a straight line, and are prone to degradation of transmission quality due to obstructions. Unlike conventional mobile communication systems, millimeter wave radio waves are significantly attenuated when passing through window glass, hindering communication through the window glass. This problem is more pronounced in windows made of double-glazed glass, which has high thermal insulation properties, than in windows made of a single pane of glass. In particular, because the millimeter wave band uses a wide frequency band for communication (e.g., in Japan, the 28 GHz band covers a 4 GHz band from 26 to 30 GHz), it is difficult to realize windows that transmit radio waves with sufficient strength across the entire frequency band.

[0003] To solve this problem, Patent Document 1 proposes a means for improving the radio wave transmission characteristics of a windshield by making the thickness and relative dielectric constant of the antireflection layer in an intermediate film made up of a resin layer and an antireflection layer and the glass plate satisfy a certain relationship. This allows millimeter waves to be efficiently transmitted through the windshield and irradiated outside the vehicle when a millimeter wave radar device is placed inside the vehicle, thereby improving the transmission characteristics of radio waves at a specific radio wave frequency of 76 to 77 GHz.

[0004] Furthermore, Patent Document 2 proposes a double-glazed window in which the transmittance of 5G radio waves is improved by providing a film structure on each of the outer and inner glass layers of the double-glazed glass. This document requires that the substrate have a slotted conductive structure. Furthermore, Patent Document 3, while not mentioning 5G, proposes that in a radio wave-transmitting body having, in this order, a first layer made of a surface finishing material such as concrete or glass, a second layer made of an air layer or the like having a relative dielectric constant of 1 to 1.5, and a third layer made of a low-dielectric-constant material, the relative dielectric constants of the first layer > the third layer > the second layer, and the thicknesses of each medium are equal to an integer multiple of half the electromagnetic wavelength (the half wavelength of the electromagnetic wave in each medium, Co / 2f√εr). Good performance can be achieved.

[0005] JP 2019-214129 A U.S. Patent Application Publication No. 2021 / 0050881 JP 6-196915 A

[0006] However, the technology of Patent Document 1 has a structure in which an interlayer film is sandwiched and bonded between two glass sheets, so there is no hollow layer, and while it is expected to improve millimeter wave transmittance at specific frequencies used in millimeter wave radar devices inside vehicle cabins, when applied to double-glazed glass, focusing only on the glass sheets and the anti-reflection wave-transmitting film layer does not propose a method for improving radio wave transmittance over a wider frequency band than that used in communications (e.g., the 4 GHz band from 26 to 30 GHz in the 28 GHz band in Japan). Furthermore, Patent Document 1 primarily aims to improve the millimeter wave transmittance characteristics of windshields installed at an angle to laminated glass for vehicles, and does not anticipate improving the radio wave transmittance of vertically installed glass windows, particularly glass windows installed on the sides of buildings and railway vehicles. On the other hand, it is possible to improve the communication environment by increasing the number of communication base stations and installing them near each household to increase the strength of radio waves reaching the household, but since base stations constantly consume power, this energy consumption cannot be ignored.

[0007] Furthermore, the technology of Patent Document 2 involves attaching a sheet with irregularities of 0.2λ to 2λ (λ is the wavelength of radio waves) and 0.2λ to 2λ in depth to a glass plate. However, since the wavelength of radio waves in the millimeter wave band (26 to 300 GHz) is 1 mm to 11.5 mm, this results in a window glass with an affixed sheet with irregularities of 0.2 mm minimum to 23 mm maximum. Glass windows with such irregularities scatter light, making it impossible to create a glass window that provides a clear view. Furthermore, the technology of Patent Document 2 does not take into consideration the thickness and relative dielectric constant of each glass plate and air gap in the double-glazed glass. Furthermore, the technology of Patent Document 3 aims to improve radio wave transmittance by making the thickness of each layer equal to an integer multiple of half the electromagnetic wavelength (the half wavelength of the electromagnetic waves in each medium, Co / 2f√εr). However, float glass, which is widely used for window glass, is allowed to have a thickness variation according to JIS R 3202:1996, and for example, the tolerance for a 10 mm glass plate is ±0.6 mm. This value corresponds to ±0.24 wavelengths (εr 6.5, 48 GHz), making it difficult to construct a radio wave transmitting window as designed using commonly used float glass.

[0008] The present invention has been made in view of the above circumstances, and has an object to provide a window that has good radio wave transmittance across the entire millimeter wave band (24 to 300 GHz) and that provides a clear view without light scattering, even when using float glass, a typical window glass sheet, and a method for manufacturing the same.

[0009] As a result of extensive research to solve the above problems, the present inventors have found that even when float glass having variations in thickness is used, the thickness of each glass plate or each hollow layer can be reduced. n ・√ε n The inventors have discovered that a window having a continuous frequency range in which the d√ε / λ value and the d√ε / λ value satisfy a certain relationship and in which the reflectivity of radio waves in the target communication frequency band is 50% or less provides a clear view without light scattering and has good radio wave transmittance over the entire millimeter wave frequency band, thereby completing the present invention.

[0010] That is, the present invention provides: 1. A double glazing unit comprising glass sheets arranged facing each other with a gap therebetween and a hollow layer formed between the glass sheets, and a frame for holding the outer edge of the double glazing unit, the double glazing unit having a continuous frequency range in which the reflectivity of radio waves is 50% or less in a target communication frequency band included in the frequency band of 24 to 300 GHz, and the d of each of the glass sheets and the hollow layer n ・√ε n / λ value satisfies the following formula (1), and d n ・√ε n A window in which the sum of d·√ε / λ values ​​satisfies the following formula (2): n -0.1≦d n ・√ε n / λ≦0.5N n +0.1 (1) (where d n is the thickness of each layer (mm), and ε n is the relative permittivity of each layer at the intermediate frequency of the target communication frequency band, λ is the radio wave wavelength (mm) at the intermediate frequency, N is a natural number from 1 to 100, and n is the number of each layer.) 0.5N-0.2≦d・√ε / λ≦0.5N+0.2 (2) (In the formula, N has the same meaning as above.) Here, the intermediate frequency and its radio wave wavelength λ are any of the values ​​shown in Table 1 below, and the target communication frequency band is a frequency band having a continuous region width of 3 to 17 GHz with the intermediate frequency shown in Table 1 below as a median. 2. A window according to claim 1, wherein the surface of the glass plate does not have a structure having an uneven shape; 3. The glass plate is a float glass, and the window further comprises an adjusting mechanism for adjusting the thickness of the hollow layer, and at least d of the glass plate n ・√ε n Window 1 or 2, whose / λ value satisfies the following formula (1-1) or (1-2): 0.5N n -0.1≦d n ・√ε n / λ<0.5N n (1-1) 0.5N n <d n ・√ε n / λ≦0.5N n +0.1 (1-2) (where d n, ε n , λ, N, and n have the same meanings as above.) 4. When the d·√ε / λ value exceeds 5, n ・√ε n Window 1 or 2 in which the / λ value satisfies the following formula (3) and the d·√ε / λ value satisfies the following formula (4), n −0.05≦d n ・√ε n / λ≦0.5N n +0.05 (3) (where d n , ε n , λ, N, and n have the same meanings as above.) 0.5N-0.1≦d·√ε / λ≦0.5N+0.1 (4) (wherein N has the same meaning as above.) 5. The glass plate is float glass, and an adjusting mechanism for adjusting the thickness of the hollow layer is further provided, and at least d of the glass plate n ・√ε n Window 4, whose / λ value satisfies the following formula (3-1) or (3-2): 0.5N n −0.05≦d n ・√ε n / λ<0.5N n (3-1) 0.5N n <d n ・√ε n / λ≦0.5N n +0.05 (3-2) (where d n , ε n, λ, N, and n have the same meanings as above.) 6. The window of 1 or 2, in which the intermediate frequency and its radio wave wavelength λ are included in the frequency range, 7. The window of 1 or 2, in which the frequency range is a continuous range width of 3 GHz or more, 8. The window of 1 or 2, in which the target communication frequency band is a communication frequency band for smartphone terminals or tablet terminals, 9. The window of 1 or 2, in which the double-glazed glass is arranged at intervals via a spacer, which is an adjustment mechanism for adjusting the thickness of the hollow layer, 10. The window of 1 or 2, in which the glass plate is float glass with an inorganic film or an organic film, or laminated glass, 11. The window of 7, in which the inorganic film or organic film is a low-emissivity (Low-E) film, 12. 12. A window manufacturing method according to claim 1, comprising: a step of preparing two or more float glasses that satisfy the formula (1), where λ is the radio wave wavelength of an intermediate frequency in a target communication frequency band included in the 24 to 300 GHz frequency band; a step of arranging the prepared two or more float glasses opposite each other at a predetermined distance via an adjustment mechanism that adjusts the thickness of the hollow layer, and assembling the two or more float glasses so that the hollow layers formed between each float glass and between the float glasses satisfy the formulas (1) and (2), to obtain a double-glazed glass; a step of integrating the obtained double-glazed glass with a frame to obtain a window; and a step of confirming that the reflectivity of radio waves in the target communication frequency band for the obtained window is in a frequency range of 50% or less; 13. A window manufacturing method according to claim 12, wherein in the step of obtaining double-glazed glass, the float glasses satisfy the following formula (1-1) or (1-2): n -0.1≦d n ・√ε n / λ<0.5N n (1-1) 0.5N n <d n ・√ε n / λ≦0.5N n +0.1 (1-2) (where d n , ε n , λ, N, and n have the same meanings as above.) 14. A method for manufacturing a window according to claim 12, wherein the frequency range is a continuous frequency band of 3 GHz or more.

[0011] Even when manufactured using commonly used, inexpensive float glass, the window of the present invention maintains a clear view, which is the essential function of a window, while suppressing the reflectivity of radio waves, thereby achieving good radio wave transmission across the entire millimeter wave frequency band. By using a window of the present invention with these properties, a good wireless communication environment can be achieved indoors while ensuring economic rationality, and the number of outdoor wireless base stations can be reduced, contributing to a reduction in the energy (electricity) required to operate the base stations.

[0012] 1 is a conceptual diagram for explaining a frequency range in which the reflectivity of radio waves is 50% or less and intermediate frequencies in the present invention.

[0013] The present invention will be described in detail below. A window according to the present invention comprises double-glazed glass having glass panes arranged facing each other at a distance and a hollow space formed between the glass panes, and a frame that holds the outer edge of the double-glazed glass. More specifically, the window according to the present invention comprises a frame (sash) consisting of an upper frame, a lower frame, one vertical frame, and the other vertical frame, and double-glazed glass (a shoji screen body) whose outer edge is held by the frame to form the window surface. If necessary, the outer edge of the double-glazed glass may be held by a middle sash in addition to the frame to form the window surface.

[0014] The material of the glass plate is not particularly limited as long as it is transparent to visible light. Examples include inorganic glass such as soda glass, borosilicate glass, aluminosilicate glass, and quartz glass, and fluorine-containing glass thereof, as well as resin-based materials such as polymethyl methacrylate (PMMA), polycarbonate (PC), and amorphous polyolefin. From the viewpoints of mechanical strength and radio wave transmittance, the thickness of the glass plate is preferably 0.5 to 50 mm, more preferably 1 to 30 mm, and even more preferably 2 to 20 mm. From the viewpoints of radio wave transmittance and glass manufacturing costs, the relative dielectric constant (ε) of the glass plate is preferably 2 to 10, more preferably 3 to 9, even more preferably 3 to 7, and even more preferably greater than 5 and 7 or less. The glass plate may be manufactured by a known manufacturing method or may be a commercially available product. However, from the viewpoint of ensuring economic rationality, it is preferable to use commonly used, inexpensive float glass. The thickness of the float glass is as described above, but thickness variation is permitted according to JIS R 3202:1996.

[0015] Although the glass plate can be used as it is, it is preferable to provide a low-emissivity (Low-E) film on at least one of the main surfaces of the glass plate from the viewpoint of reducing the penetration of heat rays and saving energy required for indoor air conditioning. Examples of the low-emissivity (Low-E) film include dielectric films such as inorganic films and organic films that do not contain conductive materials that absorb radio waves.

[0016] The inorganic film is preferably a multilayer film formed by laminating two or more layers selected from a metal oxide layer, a metal nitride layer, and a metal oxynitride layer. Examples of the metal oxide layer include a tin oxide layer, a titanium oxide layer, a silicon oxide layer, or a zinc oxide layer. Examples of the metal nitride layer include a silicon nitride layer. Examples of the metal oxynitride layer include a silicon oxynitride layer. The inorganic film is preferably formed by a vacuum film formation method such as physical vapor deposition (PVD), and particularly preferably by sputtering, because it can form a uniform film over a large area.

[0017] Examples of organic films include single-layer films or multilayer films formed by laminating two or more layers of thermoplastic resins such as polyethylene naphthalate (PEN) resin, polymethyl methacrylate resin (PMMA), amorphous polyolefin, polycarbonate (PC), polyvinyl chloride, polyethylene, polypropylene, polytetrafluoroethylene, and polyvinyl butyral, with multilayer films being preferred. The organic film can be formed by a conventional multilayer film manufacturing method, such as forming a thermoplastic resin into a film by a known method such as heat stretching, forming this into a single layer or a multilayer film formed by alternately laminating two or more layers with different dielectric constants, and then further stretching the film to obtain a film of the desired thickness. In addition, for the purpose of improving the performance of the low-emissivity (Low-E) film, an inorganic film may be provided on the organic film, or an organic film may be provided on the inorganic film.

[0018] The glass plate used in the present invention may be a single plate, or may be a laminated glass having a structure in which an interlayer film such as a shatterproof film or the above-mentioned low-emissivity (Low-E) film is sandwiched between two glass plates and bonded to each other.

[0019] The double glazing can use two or more glass plates as long as a hollow layer is formed between the glass plates. The combination of glass plates can also be appropriately selected, such as a combination of glass plates with the same thickness and dielectric constant, a combination of glass plates with the same dielectric constant but different thicknesses, or a combination of glass plates with the same thickness but different dielectric constants.

[0020] The thickness of the hollow layer can be appropriately set so as to satisfy the mathematical formula of the present invention, taking into consideration the thickness and relative dielectric constant of the glass plate, but from the viewpoint of radio wave transmittance, it is preferably 1 to 500 mm, more preferably 1 to 300 mm, even more preferably 1 to 150 mm, even more preferably 1 to 100 mm, even more preferably 4 to 80 mm, even more preferably 7 to 60 mm, and even more preferably 10 to 50 mm. The thickness of this hollow layer can be adjusted by an adjustment mechanism for adjusting the thickness of the hollow layer, such as a spacer, which will be described later.

[0021] The materials for the frames constituting the windows of the present invention include metals such as aluminum, resins such as polyvinyl chloride, and wood. Among these, polyvinyl chloride is preferred from the viewpoints of mechanical strength, weather resistance, thermal insulation, flame retardancy, formability, manufacturing costs, etc. Each frame is formed with a mating recess formed between a pair of side walls on the inner periphery, and is configured to engage and hold the outer edge of the double-glazed glass. If necessary, the mating recess may be filled with a heat-resistant material such as silicone resin to hold the double-glazed glass.

[0022] When the window size is large, spacers can be placed to control the desired thickness in order to improve the accuracy of the thickness of the hollow layer in the double-glazed glass. Examples of materials for the spacer include resin materials such as polyvinyl chloride, various metals such as aluminum and brass, and glass materials such as borosilicate glass and soda glass. There are no particular restrictions on the placement of the spacer, but it is preferable to place it on the periphery of the double-glazed glass in order to ensure unobstructed views of the outdoors. When installing a spacer, it is preferable to fix the spacer and the glass panes in close contact with each other so that no gaps occur between them. The spacer may be provided separately from the frame, or the frame and spacer may be integrated. It is also possible to provide the spacer on the frame.

[0023] The window of the present invention has a continuous frequency range in which the radio wave reflectance is 50% or less in a target communication frequency band included in the frequency band of 24 to 300 GHz, and d n ・√ε n / λ value satisfies the following formula (1), and d n ・√ε n The total value of d·√ε / λ satisfies the following formula (2).

[0024] 0.5N n -0.1≦d n ・√ε n / λ≦0.5N n +0.1 (1) (where d n is the thickness of each layer (mm), and ε nis the relative permittivity of each layer at the intermediate frequency of the target communication frequency band, λ is the radio wave wavelength (mm) at the intermediate frequency, N is a natural number from 1 to 100, and n is the number of each layer.) 0.5N-0.2≦d・√ε / λ≦0.5N+0.2 (2) (In the formula, N has the same meaning as above.) Here, the intermediate frequency and its radio wave wavelength λ are any of the values ​​shown in Table 2 below, and the target communication frequency band is a frequency band having a continuous region width of 3 to 17 GHz with the intermediate frequency shown in Table 2 below as the median.

[0025]

[0026] The "thin film interference formula" used to verify the radio wave transmittance of a window in this invention is a proven calculation method applied to the design of many electromagnetic wave (radio waves and light) products, and this formula can be used to derive solutions for reflectance and transmittance at specific frequencies (wavelengths). However, this formula does not derive a window structure that provides good radio wave transmittance characteristics across the entire communication frequency band. Therefore, the inventors conducted extensive research to find a window structure that provides good radio wave transmittance across the entire target communication frequency band (e.g., 26 to 30 GHz), and discovered that the above formulas (1) and (2) must be satisfied.

[0027] Here, millimeter waves generally refer to a frequency band of 30 to 300 GHz, but in this specification, millimeter waves refer to a frequency band in the frequency range of 24 to 300 GHz, which includes so-called general millimeter waves as well as 24.25 to 52.6 GHz of FR2 (Frequency Range 2), a frequency band used in 5G.

[0028] Furthermore, the target communication frequency band refers to a frequency band allocated to each telecommunications carrier, but also includes a continuous frequency band that can collectively cover the frequency bands allocated to multiple telecommunications carriers. The target communication frequency band varies depending on the country or region in which the communication device is used. The present invention targets communication frequency bands allocated to telecommunications carriers that provide services to mobile communication terminals, such as smartphones and tablet devices. For example, in Japan, the 27-29.5 GHz frequency band is allocated to four major telecommunications carriers as the 5G millimeter wave band, and a 26.5-29.5 GHz frequency band is planned to be allocated in the future. Therefore, if a window with improved radio wave transmittance can be provided for the target communication frequency band of 26-30 GHz, it will be possible to provide a window with improved radio wave transmittance for the frequencies allocated by the four domestic carriers.

[0029] The window of the present invention has a continuous frequency range in which the radio wave reflectance is 50% or less in the target communication frequency band, from the viewpoint of reliably obtaining a window with good radio wave transmission properties in the 24 to 300 GHz frequency band, which is the target frequency band allocated in each country. Here, a continuous frequency range in which the radio wave reflectance is 50% or less refers to a continuous frequency range in which the reflectance is 50% or less when the reflectance is measured while changing the frequency, as shown in Figure 1, for example. In consideration of the width of the frequency band allocated to telecommunications carriers, the frequency range is preferably a continuous range width of 3 GHz or more, more preferably 5 GHz or more, and even more preferably 7 GHz or more. While there is no particular upper limit to the frequency range, 17 GHz or less is preferred, taking into account the relative dielectric constant and thickness of practical glass sheets. The standard for a radio wave reflectance of 50% or less is based on the 3 dB insertion loss acceptance standard of the TIA / EIA-568B standard. Here, an insertion loss of 3 dB means that there is a loss of 50%, which corresponds to a reflectance of 50% when applied to a window.

[0030] d n ・√ε n / λ is the optical distance (d n ・√ε n) divided by the wavelength (λ), and can be defined independently of the relative permittivity of the material or the target frequency band. n ・√ε n / λ is used to explain the interference of electromagnetic waves, and d n ・√ε n When / λ is an integer multiple (N), it means that the phases of the electromagnetic waves that have passed through the dielectric and the electromagnetic waves that have not passed through the dielectric are the same. n ・√ε n When / λ is an integral multiple / 2, that is, 0.5N, the phases of the electromagnetic waves that have passed through the dielectric and the electromagnetic waves that have not passed through the dielectric are opposite, meaning that the electromagnetic waves cancel each other out, and the reflectance becomes minimal.

[0031] In the present invention, the d of the glass plate constituting the window n ・√ε n Not only / λ but also the d n ・√ε n / λ and the d of the glass plate and the hollow layer n ・√ε n By setting the total value of d·√ε / λ within a predetermined range based on 0.5N times as the standard and suppressing the reflectivity of radio waves, it is possible to achieve good radio wave transparency over the entire frequency range of the millimeter wave band.

[0032] Here, in formula (1), d of the glass plate n ・√ε n Not only the / λ value but also the d n ・√ε n The reason for specifying the / λ value is that radio waves are also interfered with in the air space where no glass is present. n ・√ε n If the / λ value does not satisfy the formula (1), the continuous frequency range in which the reflectance is 50% or less will be narrow, and part or all of the continuous frequency range in which the reflectance is 50% or less will be shifted to a range other than the target frequency band, making it impossible to have good radio wave transmittance.

[0033] In addition, in the formula (2), d of each layer n ・√ε n Not only the / λ value, but also each dn ・√ε n The reason for specifying the d √ε / λ value, which is the sum of the d √ε / λ values, is that the double glazing as a whole, including the hollow layer, also contributes to radio wave interference. Even if each glass sheet satisfies the above formula (1), if the d √ε / λ value of the entire window does not satisfy the following formula (2), part or all of the continuous frequency range in which the reflectance is 50% or less will shift to a range outside the target frequency band, and good radio wave transmittance will not be achieved.

[0034] That is, in the present invention, by defining d·√ε / λ defined by the formula (2), an important effect of ensuring good radio wave transmittance is achieved. In this regard, in Example 24 described later, the d of each layer of the glass plate is n ・√ε n On the other hand, in Comparative Example 4, the d of each layer is varied with the same glass thickness as in Example 24, and the d √ε / λ of each layer is also varied. n ・√ε n Although the window is constructed so that d √ε / λ is within the specified range, the d √ε / λ of the entire window is outside the specified range, and therefore sufficient radio wave transmittance cannot be ensured. If d √ε / λ in formula (2) is not specified, the d n ・√ε n It is necessary to set a stricter standard value for / λ. This means that it will be difficult to "achieve a good indoor wireless communication environment while ensuring economic rationality."

[0035] In addition, when the glass plate is a glass plate with an inorganic film or an organic film, these films and the glass plate are regarded as an integral structure, and are counted as one layer. n ・√ε n For example, in the case of a glass plate with an inorganic or organic film, the d n ・√ε n / λ value and d of glass plate n ・√ε n After deriving the / λ values, n ・√ε n By adding up the / λ values, the d of the layer of the inorganic film or organic film-coated glass plate can be calculated. n ・√εn In addition, when the glass sheets are laminated glass, each glass sheet and the interlayer film are regarded as an integral structure, and the d n ・√ε n / λ value is derived.

[0036] In formula (1), d n is the thickness (mm) of each layer of the glass plate and the hollow layer, and the preferred range is as described above. n is the relative permittivity of each layer at the intermediate frequency of the target communication frequency band. Here, the intermediate frequency refers to the intermediate frequency of the target communication frequency band in the case where the target communication frequency band is known in advance for a window. For example, if the target communication frequency band for a window is 26 to 30 GHz, the intermediate frequency is 28 GHz. On the other hand, for a window where the target communication frequency band is unknown, the intermediate frequency refers to the intermediate frequency in a continuous frequency range where the reflectivity of the window is measured and the radio wave reflectivity is 50% or less, as shown in Figure 1. In Figure 1, the intermediate frequency is read as 38.5 GHz, but it is not necessarily limited to this value and has a range of ±2 GHz. λ is the radio wave wavelength (mm) at the intermediate frequency. If the wavelength of the intermediate frequency in the target communication frequency band is λ, λ is preferably 0.8λ to 1.2λ, more preferably 0.9λ to 1.1λ, and even more preferably 0.95λ to 1.05λ. N is a natural number between 1 and 100, preferably between 1 and 50, more preferably between 1 and 30, and even more preferably between 1 and 20. While N can be any natural number between 1 and 100, it is preferable to design the thicknesses of the glass sheets and the hollow layer to satisfy required characteristics other than radio wave transmittance, such as thermal insulation and mechanical strength, and use the N closest to those design values. Furthermore, n represents the number of each layer. For example, in a double-glazed glass structure consisting of glass sheet 1, hollow layer, and glass sheet 2, glass sheet 1 is the first layer (n = 1), the intermediate layer is the second layer (n = 2), and glass sheet 2 is the third layer (n = 3). n is preferably an integer between 1 and 30, more preferably between 1 and 20, and even more preferably between 1 and 10. The number of layers in the double-glazed glass is preferably between 3 and 31, more preferably between 3 and 21, and even more preferably between 3 and 11.

[0037] In the present invention, at least the dn ・√ε n It is preferable that the / λ value further satisfies the following formula (1-1) or formula (1-2): n -0.1≦d n ・√ε n / λ<0.5N n (1-1) 0.5N n <d n ・√ε n / λ≦0.5N n +0.1 (1-2)

[0038] In the above formula (1), d of each glass plate n ・√ε n When using the above-mentioned float glass, it is difficult to adjust the / λ value to an integral multiple / double, i.e., exactly 0.5N, due to the influence of variations in thickness. n ・√ε n If the / λ value satisfies the above formula (1-1) or formula (1-2), then d n ・√ε n Even if the / λ value is not adjusted to exactly 0.5N, a window with good radio wave transmittance can be obtained. In the case of a window made of polished glass or the like whose thickness can be accurately adjusted, simply n ・√ε n This does not apply because a glass plate with a specified value of / λ can be used. n = d n ・√ε n Windows using glass plates for which the above equations are true do not fall under these formulas.

[0039] Furthermore, when the d·√ε / λ value exceeds 5, the d·√ε / λ value is set to 5. In the target communication frequency band included in the frequency band of 24 to 300 GHz, the d·√ε / λ value is set to 5. In addition ... in the target communication frequency band included in the frequency band of 24 to 300 GHz, the d·√ε / λ value is set to 5. In addition, in the target communication frequency band included in the frequency band of 24 to n ・√ε n / λ value satisfies the following formula (3), and d n ・√ε n It is preferable that the total value of d·√ε / λ satisfies the following formula (4).

[0040] 0.5N n −0.05≦dn ・√ε n / λ≦0.5N n +0.05 (3) (where d n , ε n , λ, N, and n have the same meanings as above.) 0.5N-0.1≦d·√ε / λ≦0.5N+0.1 (4) (wherein N has the same meaning as above.)

[0041] As the d √ε / λ value of the window increases, the frequency range in which the reflectance is 50% or less becomes narrower. n ・√ε n From the viewpoint of controlling the d·√ε / λ and d·√ε / λ values, when the d·√ε / λ value exceeds 5, it is preferable to satisfy the formula (3) and the formula (4).

[0042] d of each glass plate and each hollow layer n ・√ε n When the d √ε / λ value does not satisfy the formula (3), the continuous frequency range in which the reflectance is 50% or less becomes narrower, and part or all of the continuous frequency range in which the reflectance is 50% or less shifts to a range other than the target frequency band, making it impossible to have good radio wave transmittance. Also, when the d √ε / λ value does not satisfy the formula (4), part or all of the continuous frequency range in which the reflectance is 50% or less shifts to a range other than the target frequency band, making it impossible to have good radio wave transmittance.

[0043] For the same reasons as those mentioned above, at least d of each glass plate n ・√ε n It is preferable that the / λ value further satisfies the following formula (3-1) or (3-2): n −0.05≦d n ・√ε n / λ<0.5N n (3-1) 0.5N n <d n ・√ε n / λ≦0.5N n +0.05 (3-2)

[0044] Furthermore, from the viewpoint of providing a window with high radio wave transmittance while providing a clear view without light scattering, which is the essential function of a window, it is preferable to avoid laminating a structure such as a film having an uneven shape on the window surface. Laminating such a structure such as a film having an uneven shape on the window surface may result in failure to achieve the object of the present invention. Examples of uneven shapes include unevenness with a width of 0.2λ to 2λ (λ is the wavelength of radio waves) and a depth of 0.2λ to 2λ, as disclosed in Patent Document 2. Similarly, it is undesirable to have a slotted conductive structure, as required by Patent Document 2, and one aspect of the present invention does not include such a slotted conductive structure.

[0045] Next, a method for manufacturing a window according to the present invention will be described. When λ is the wavelength of an intermediate frequency radio wave in a target communication frequency band included in the 24 to 300 GHz frequency band, glass plates, preferably float glass, that satisfy the above formula (1), preferably formula (1-1) or formula (1-2), more preferably formula (3), and even more preferably formula (3-1) or formula (3-2), are prepared. Two or more of the prepared glass plates are arranged facing each other at a predetermined distance, and assembled to obtain double-glazed glass so that the hollow layers formed between each glass plate and between the glass plates satisfy the above formula (1), preferably formula (1-1) or formula (1-2) and formula (2), more preferably formula (3), and even more preferably formula (3-1) or formula (3-2) and formula (4). In this case, as described above, it is possible to provide a spacer that can control the thickness of the hollow layer. The outer edge of the double-pane glass is then engaged and held in the mating recess formed between a pair of side wall portions on the inner periphery of each frame, thereby integrating the double-pane glass and each frame, thereby obtaining the window of the present invention.

[0046] EXAMPLES The present invention will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0047] Example 1: The intermediate frequency in the target communication frequency band (26-30 GHz) was 28 GHz, and a window with a double-pane structure (total three-layer structure) was manufactured by integrating two glass plates and a polyvinyl chloride frame using the following soda quartz glass plates, each having a dielectric constant (ε) of 6.5 at a radio wave wavelength (λ) of 10.7 mm for that frequency. The glass plates were assembled so that each layer satisfied the following formulas (1) and (2): First layer glass plate thickness (d1) = 4.20 mm, dielectric constant (ε1) = 6.50; Second layer hollow layer thickness (d2) = 10.71 mm, dielectric constant (ε2) = 1.00; Third layer glass plate thickness (d3) = 4.20 mm, dielectric constant (ε3) = 6.50.

[0048] The frequency range of the obtained window with a reflectance of 50% or less in the range of 26 to 30 GHz spans a continuous frequency band of 8.20 GHz. n ・√ε n / λ and d n ・√ε n The total ε / λ value, d·√ε / λ, was as follows, satisfying formulas (1) and (2): First layer glass plate: d1·√ε1 / λ = 1.00... twice 0.5 Second layer hollow layer: d2·√ε2 / λ = 1.00... twice 0.5 Third layer glass plate: d3·√ε3 / λ = 1.00... twice 0.5 Total value of the above three layers: d·√ε / λ = 3.00... six times 0.5

[0049] Next, to confirm the frequency characteristics of the reflectance and radio wave transmission power of the obtained window, a thin film interference calculation formula was used to simulate the reflectance and transmission power versus frequency within the target frequency range, creating curves of reflectance and transmission power versus frequency, and calculating the maximum reflectance and maximum radio wave transmission power loss. The results are shown in Table 3. It was confirmed that good radio wave transmission was achieved in both cases within the range of 26 to 30 GHz.

[0050] Example 2 A window with a triple-pane structure (a total of five layers) was manufactured by assembling the following glass plates, each of which has an intermediate frequency of 28 GHz in the target communication frequency band (26 to 30 GHz) and a relative dielectric constant (ε) of 6.5 at a radio wave wavelength (λ) of 10.7 mm at that frequency, so that each layer satisfied the mathematical expressions (1) and (2). The glass plates were assembled so that each layer satisfied the mathematical expressions (1) and (2). Thickness of first glass plate (d1) = 4.62 mm, relative dielectric constant (ε1) = 6.50 Thickness of second hollow layer (d2) = 10.71 mm, relative dielectric constant (ε2) = 1.00 Thickness of third glass plate (d3) = 2.10 mm, relative dielectric constant (ε3) = 6.50 Thickness of fourth hollow layer (d4) = 10.71 mm, relative dielectric constant (ε4) = 1.00 Thickness of fifth glass plate (d5) = 4.20 mm, relative dielectric constant (ε5) = 6.50

[0051] The frequency range of the obtained window with a reflectance of 50% or less in the range of 26 to 30 GHz spans a continuous frequency band of 7.98 GHz. n ・√ε n / λ and d n ・√ε n The total ε / λ value, d·√ε / λ, was as follows, satisfying formulas (1) and (2): First layer glass plate: d1·√ε1 / λ = 1.10...2 times 0.5 + 0.1 Second layer hollow layer: d2·√ε2 / λ = 1.00...2 times 0.5 Third layer glass plate: d3·√ε3 / λ = 0.50...1 times 0.5 Fourth layer hollow layer: d4·√ε4 / λ = 1.00...2 times 0.5 Fifth layer glass plate: d5·√ε5 / λ = 1.00...2 times 0.5 Total value of the above five layers: d·√ε / λ = 4.60...9 times 0.5 + 0.1

[0052] Next, to confirm the frequency characteristics of the reflectance and radio wave transmission power of the obtained window, the maximum reflectance and maximum radio wave transmission power loss were calculated by simulation using the thin film interference calculation formula, as in Example 1. The results are shown in Table 3. It was confirmed that good radio wave transmission was ensured in both cases in the range of 26 to 30 GHz.

[0053] Example 3 A window with a triple-pane structure (a total of five layers) in which three glass plates and a frame were integrated was manufactured using the following glass plates, which have an intermediate frequency of 28 GHz in the target communication frequency band (26 to 30 GHz) and a relative dielectric constant (ε) of 6.5 at a radio wave wavelength (λ) of 10.7 mm at that frequency. The glass plates were assembled so that each layer satisfied the mathematical expressions (1) and (2). Thickness of first glass plate (d1) = 6.30 mm, relative dielectric constant (ε1) = 6.50 Thickness of second hollow layer (d2) = 10.93 mm, relative dielectric constant (ε2) = 1.00 Thickness of third glass plate (d3) = 6.30 mm, relative dielectric constant (ε3) = 6.50 Thickness of fourth hollow layer (d4) = 10.71 mm, relative dielectric constant (ε4) = 1.00 Thickness of fifth glass plate (d5) = 8.24 mm, relative dielectric constant (ε5) = 6.50

[0054] The frequency range of the obtained window with a reflectance of 50% or less in the range of 26 to 30 GHz spans a continuous frequency band of 5.40 GHz. n ・√ε n / λ and d n ・√ε n The total ε / λ value, d·√ε / λ, was as follows, satisfying formulas (1) and (2): First glass sheet: d1·√ε1 / λ = 1.50...3 times 0.5 Second hollow layer: d2·√ε2 / λ = 1.02...2 times 0.5 + 0.02 Third glass sheet: d3·√ε3 / λ = 1.50...3 times 0.5 Fourth hollow layer: d4·√ε4 / λ = 1.00...2 times 0.5 Fifth glass sheet: d5·√ε5 / λ = 1.96...4 times 0.5 - 0.04 Total value of the above five layers: d·√ε / λ = 6.98...14 times 0.5 - 0.02

[0055] Next, to confirm the frequency characteristics of the reflectance and radio wave transmission power of the obtained window, the maximum reflectance and maximum radio wave transmission power loss were calculated by simulation using the thin film interference calculation formula, as in Example 1. The results are shown in Table 3. It was confirmed that good radio wave transmission was ensured in both cases in the range of 26 to 30 GHz.

[0056] Example 4 A window with a triple-pane structure (a total of five layers) was manufactured by assembling the following glass plates, each of which has an intermediate frequency of 48 GHz in the target communication frequency band (47 to 49 GHz) and a relative dielectric constant (ε) of 6.5 at a radio wave wavelength (λ) of 6.25 mm at that frequency, so that each layer satisfied the mathematical expressions (1) and (2). The glass plates were assembled so that each layer satisfied the mathematical expressions (1) and (2). Thickness of first glass plate (d1) = 9.93 mm, relative dielectric constant (ε1) = 6.50 Thickness of second hollow layer (d2) = 15.63 mm, relative dielectric constant (ε2) = 1.00 Thickness of third glass plate (d3) = 7.23 mm, relative dielectric constant (ε3) = 6.50 Thickness of fourth hollow layer (d4) = 15.63 mm, relative dielectric constant (ε4) = 1.00 Thickness of fifth glass plate (d5) = 9.93 mm, relative dielectric constant (ε5) = 6.50

[0057] The frequency range of the obtained window with a reflectance of 50% or less in the range of 47 to 49 GHz spans a continuous frequency band of 3.80 GHz. n ・√ε n / λ and d n ・√ε n The total ε / λ value, d·√ε / λ, was as follows, satisfying formulas (1) and (2): First layer glass plate: d1·√ε1 / λ=4.05...8 times 0.5 + 0.05 Second layer hollow: d2·√ε2 / λ=2.50...5 times 0.5 Third layer glass plate: d3·√ε3 / λ=2.95...6 times 0.5 - 0.05 Fourth layer hollow: d4·√ε4 / λ=2.50...5 times 0.5 Fifth layer glass plate: d5·√ε5 / λ=4.05...8 times 0.5 + 0.05 Total value of the above five layers: d·√ε / λ=16.05...32 times 0.5 + 0.05

[0058] Next, to confirm the frequency characteristics of the reflectance and radio wave transmission power of the obtained window, the maximum reflectance and maximum radio wave transmission power loss were calculated by simulation using the thin film interference calculation formula, as in Example 1. The results are shown in Table 3. It was confirmed that good radio wave transmission was ensured in both cases in the range of 47 to 49 GHz.

[0059] Comparative Example 1 The intermediate frequency in the target communication frequency band (26 to 30 GHz) was 28 GHz, and a window with a double-glazed structure (three layers in total) was manufactured by integrating two glass plates with a frame using the following glass plates having a relative dielectric constant (ε) of 6.50 at a radio wave wavelength (λ) of 10.7 mm for that frequency: First layer glass plate thickness (d1) = 4.71 mm, relative dielectric constant (ε1) = 6.50 Second layer hollow layer thickness (d2) = 10.71 mm, relative dielectric constant (ε2) = 1.00 Third layer glass plate thickness (d3) = 4.62 mm, relative dielectric constant (ε3) = 6.50.

[0060] The frequency range of the obtained window with a reflectance of 50% or less in the range of 26 to 30 GHz is a continuous frequency band of 4.83 GHz, and the d n ・√ε n / λ and d n ・√ε n The total ε / λ value, d·√ε / λ, was as follows, and did not satisfy formulas (1) and (2): First layer glass plate: d1·√ε1 / λ = 1.12...2x0.5 + 0.12 Second layer hollow layer: d2·√ε2 / λ = 1.00...2x0.5 Third layer glass plate: d3·√ε3 / λ = 1.10...2x0.5 + 0.10 Total value of the above three layers: d·√ε / λ = 3.22...6x0.5 + 0.22

[0061] Next, to confirm the frequency characteristics of the reflectance and radio wave transmission power of the obtained window, the maximum reflectance and maximum radio wave transmission power loss were calculated by simulation using the thin film interference calculation formula, as in Example 1. The results are shown in Table 3. In all cases, good radio wave transmission was not achieved in the range of 26 to 30 GHz.

[0062] Comparative Example 2 The intermediate frequency in the target communication frequency band (26 to 30 GHz) was 28 GHz, and a window with a triple-glazed structure (a total of five layers) was manufactured by integrating three glass sheets and a frame using the following glass sheets having a relative dielectric constant (ε) of 6.50 at a radio wave wavelength (λ) of 10.7 mm for that frequency: First layer glass sheet thickness (d1) = 6.30 mm, relative dielectric constant (ε1) = 6.50 Second layer hollow layer thickness (d2) = 12.00 mm, relative dielectric constant (ε2) = 1.00 Third layer glass sheet thickness (d3) = 4.20 mm, relative dielectric constant (ε3) = 6.50 Fourth layer hollow layer thickness (d4) = 12.00 mm, relative dielectric constant (ε4) = 1.00 Fifth layer glass sheet thickness (d5) = 6.30 mm, relative dielectric constant (ε5) = 6.50

[0063] The frequency range of the obtained window with a reflectance of 50% or less in the range of 26 to 30 GHz is a continuous frequency band of 1.05 GHz, and the d n ・√ε n / λ and d n ・√ε n The total ε / λ value, d·√ε / λ, was as follows, and did not satisfy formulas (1) and (2): First glass plate: d1·√ε1 / λ = 1.50...3 times 0.5 Second hollow layer: d2·√ε2 / λ = 1.12...2 times 0.5 + 0.12 Third glass plate: d3·√ε3 / λ = 1.00...2 times 0.5 Fourth hollow layer: d4·√ε4 / λ = 1.12...2 times 0.5 + 0.12 Fifth glass plate: d5·√ε5 / λ = 1.50...3 times 0.5 Total value of the above five layers: d·√ε / λ = 6.24...12 times 0.5 + 0.24

[0064] Next, to confirm the frequency characteristics of the reflectance and radio wave transmission power of the obtained window, the maximum reflectance and maximum radio wave transmission power loss were calculated by simulation using the thin film interference calculation formula, as in Example 1. The results are shown in Table 3. In all cases, good radio wave transmission was not achieved in the range of 26 to 30 GHz.

[0065]

[0066] Example 5 A window with a triple-layer glass structure (a total of five layers) in which three glass plates and a frame were integrated was manufactured using the following glass plates, each having an intermediate frequency of 28 GHz in the target communication frequency band (26 to 30 GHz) and a relative dielectric constant (ε) of 6.5 at a radio wave wavelength (λ) of 10.7 mm at that frequency, and a low-emissivity (Low-E) coated glass plate formed on the glass plate, so that each layer satisfied the mathematical expressions (1) and (2).

[0067] Here, the low-emissivity (Low-E) coated glass plate is formed by alternately laminating polyethylene naphthalate (PEN) resin and poly(methyl methacrylate) (PMMA) resin, which have different refractive indices for infrared rays, as shown in JP-A-2004-503402, and integrating an interference-type reflective film (dielectric multilayer film) with a predetermined relative dielectric constant and having an infrared reflecting function with the glass plate. The relative dielectric constant used in designing the window is the apparent relative dielectric constant of the entire low-emissivity film. First layer glass plate: Thickness (d 11 )=8.32mm, relative permittivity (ε 11 ) = 6.50 Thickness of low emissivity film (d 12 )=0.11mm, relative dielectric constant (ε 12 ) = 4.00 Thickness of second hollow layer (d2) = 10.71 mm, relative dielectric constant (ε2) = 1.00 Thickness of third glass plate (d3) = 8.40 mm, relative dielectric constant (ε3) = 6.50 Thickness of fourth hollow layer (d4) = 10.71 mm, relative dielectric constant (ε4) = 1.00 Fifth glass plate: Low emissivity film: Thickness (d 52 )=0.11mm, relative dielectric constant (ε 52 ) = 4.00 Glass plate: Thickness (d 51 )=8.32mm, relative dielectric constant (ε 51 ) = 6.50

[0068] The frequency range of the obtained window with a reflectance of 50% or less in the range of 26 to 30 GHz spans a continuous frequency band of 5.95 GHz. n ・√ε n / λ and d n ・√ε nThe total ε / λ value, d·√ε / λ, was as follows, satisfying formulas (1) and (2): First layer glass plate: d1·√ε1 / λ = 2.00 + 0.01 = 2.00...4 times 0.5 Second layer hollow layer: d2·√ε2 / λ = 1.00...2 times 0.5 Third layer glass plate: d3·√ε3 / λ = 2.00...4 times 0.5 Fourth layer hollow layer: d4·√ε4 / λ = 1.00...2 times 0.5 Fifth layer glass plate: d5·√ε5 / λ = 0.02 + 1.98 = 2.00...4 times 0.5 Total value of the above five layers: d·√ε / λ = 8.00...16 times 0.5

[0069] Next, to confirm the frequency characteristics of the reflectance and radio wave transmission power of the obtained window, the maximum reflectance and maximum radio wave transmission power loss were calculated by simulation using the thin film interference calculation formula, as in Example 1. The results are shown in Table 4. It was confirmed that good radio wave transmission was ensured in both cases in the range of 26 to 30 GHz.

[0070] Example 6 A window with a triple-layer glass structure (a total of five layers) in which three glass plates and a frame were integrated was manufactured using the following glass plates, each having an intermediate frequency of 28 GHz in the target communication frequency band (26 to 30 GHz) and a relative dielectric constant (ε) of 6.5 at a radio wave wavelength (λ) of 10.7 mm for that frequency, and a glass plate formed by laminating a low-emissivity (Low-E) film similar to that used in Example 6 to the glass plate, so that each layer satisfied the formulas (1) and (2).

[0071] Here, the low-emissivity (Low-E) coated glass plate was a glass plate with an interference-type reflective film (dielectric multilayer film) having an infrared reflecting function and a predetermined relative dielectric constant, which was obtained by alternately laminating titanium oxide films and silicon oxide films, which have different refractive indices for infrared rays, on a glass plate as shown in WO 2014 / 010532. The relative dielectric constant used in designing the window was the apparent relative dielectric constant of the entire low-emissivity film. First layer glass plate: Glass plate: Thickness (d 11 )=8.40mm, relative permittivity (ε 11 ) = 6.50 Low emissivity film: Thickness (d 12 ) = 0.02 mm, relative permittivity (ε 12) = 7.00 Second hollow layer: Thickness (d2) = 10.71 mm, relative dielectric constant (ε2) = 1.00 Third glass plate: Thickness (d3) = 8.40 mm, relative dielectric constant (ε3) = 6.50 Fourth hollow layer: Thickness (d4) = 10.71 mm, relative dielectric constant (ε4) = 1.00 Fifth glass plate: Low-emissivity film: Thickness (d 52 ) = 0.02 mm, relative permittivity (ε 52 ) = 7.00 Glass plate: Thickness (d 51 )=8.40mm, relative permittivity (ε 51 ) = 6.50

[0072] The frequency range of the obtained window with a reflectance of 50% or less in the range of 26 to 30 GHz spans a continuous frequency band of 5.96 GHz. n ・√ε n / λ and d n ・√ε n The total ε / λ value, d·√ε / λ, was as follows, satisfying formulas (1) and (2): First layer glass plate: d1·√ε1 / λ = 2.00 + 0.01 = 2.01...4 times 0.5 + 0.01 Second layer hollow layer: d2·√ε2 / λ = 1.00...2 times 0.5 Third layer glass plate: d3·√ε3 / λ = 2.00...4 times 0.5 Fourth layer hollow layer: d4·√ε4 / λ = 1.00...2 times 0.5 Fifth layer glass plate: d5·√ε5 / λ = 0.01 + 2.00 = 2.01...4 times 0.5 + 0.01 Total value of the above five layers: d·√ε / λ = 8.01...16 times 0.5 + 0.01

[0073] Next, to confirm the frequency characteristics of the reflectance and radio wave transmission power of the obtained window, the maximum reflectance and maximum radio wave transmission power loss were calculated by simulation using the thin film interference calculation formula, as in Example 1. The results are shown in Table 4. It was confirmed that good radio wave transmission was ensured in both cases in the range of 26 to 30 GHz.

[0074] Comparative Example 3 A window with a three-layer glass structure (a total of five layers) was manufactured by integrating three glass plates with a frame as described below. The intermediate frequency in the target communication frequency band (26 to 30 GHz) was 28 GHz, and the relative dielectric constant (ε) at a radio wave wavelength (λ) of 10.7 mm of that frequency was 6.5. A low-emissivity (Low-E) film was laminated on the glass plate by the same method as in Example 5 to form a glass plate integral with an interference-type reflective film (dielectric multilayer film) having an infrared reflecting function and a predetermined relative dielectric constant. The relative dielectric constant used in designing the window was the apparent relative dielectric constant of the entire low-emissivity film. First layer glass plate: Glass plate: Thickness (d 11 )=8.40mm, relative permittivity (ε 11 ) = 6.50 Low-emissivity film glass plate: Thickness (d 12 )=0.32mm, relative dielectric constant (ε 12 ) = 4.00 Second hollow layer: Thickness (d2) = 10.07 mm, relative dielectric constant (ε2) = 1.00 Third glass plate: Thickness (d3) = 8.40 mm, relative dielectric constant (ε3) = 6.50 Fourth hollow layer: Thickness (d4) = 10.07 mm, relative dielectric constant (ε4) = 1.00 Fifth glass plate: Glass plate with low-emissivity film: Thickness (d 52 )=0.32mm, relative dielectric constant (ε 52 ) = 4.00 Glass plate: Thickness (d 51 )=8.40mm, relative permittivity (ε 51 ) = 6.50

[0075] The frequency range of the obtained window with a reflectance of 50% or less in the range of 26 to 30 GHz is a continuous frequency band of 1.33 GHz, and the d n ・√ε n / λ and d n ・√ε nThe total value of the ε / λ values, d·√ε / λ, was as follows, and did not satisfy formula (1). First layer glass plate: d1·√ε1 / λ = 2.00 + 0.06 = 2.06...4 times 0.5 + 0.06 Second layer hollow layer: d2·√ε2 / λ = 0.94...2 times 0.5 - 0.06 Third layer glass plate: d3·√ε3 / λ = 1.80...4 times 0.5 - 0.20 Fourth layer hollow layer: d4·√ε4 / λ = 0.94...2 times 0.5 - 0.06 Fifth layer glass plate: d5·√ε5 / λ = 0.06 + 2.00 = 2.06...4 times 0.5 + 0.06 Total value of the above five layers: d·√ε / λ = 7.80...16 times 0.5 - 0.02

[0076] Next, to confirm the frequency characteristics of the reflectance and radio wave transmission power of the obtained window, the maximum reflectance and maximum radio wave transmission power loss were calculated by simulation using the thin film interference calculation formula, as in Example 1. The results are shown in Table 4. In all cases, good radio wave transmission was not achieved in the range of 26 to 30 GHz.

[0077]

[0078] [Examples 7 to 23] Using the glass plates shown in Table 5 according to the target communication frequency band, windows with a double-glazed structure (three layers in total) were manufactured by assembling two glass plates and a frame so that each layer satisfied the formulas (1) and (2). The frequency range of the obtained windows with a reflectance of 50% or less in the target communication frequency band all spanned a continuous frequency band of 17 GHz or higher, and the d of each layer n ・√ε n / λ and d n ・√ε n As shown in Table 5, the total value of d·√ε / λ also satisfied the formulas (1) and (2).

[0079] Next, to confirm the frequency characteristics of the reflectance and radio wave transmission power of the obtained window, the maximum reflectance and maximum radio wave transmission power loss were calculated by simulation using the thin film interference calculation formula, as in Example 1. As a result, as shown in Table 5, in each target communication frequency band, the maximum reflectance value was 46% or less, and the maximum radio wave transmission power loss was 2.7 dB or less, confirming that good radio wave transmission properties could be ensured.

[0080]

[0081] Example 24 A window with a triple-pane structure (a total of five layers) in which three glass plates and a frame were integrated was manufactured using the following glass plates, which have an intermediate frequency of 48 GHz in the target communication frequency band (46 to 50 GHz) and a relative dielectric constant (ε) of 6.5 at a radio wave wavelength (λ) of 10.7 mm at that frequency. The glass plates were assembled so that each layer satisfied the mathematical expressions (1) and (2). Thickness of first glass plate (d1) = 7.55 mm, relative dielectric constant (ε1) = 6.50 Thickness of second hollow layer (d2) = 12.50 mm, relative dielectric constant (ε2) = 1.00 Thickness of third glass plate (d3) = 7.55 mm, relative dielectric constant (ε3) = 6.50 Thickness of fourth hollow layer (d4) = 12.50 mm, relative dielectric constant (ε4) = 1.00 Thickness of fifth glass plate (d5) = 7.16 mm, relative dielectric constant (ε5) = 6.50

[0082] The frequency range of the obtained window with a reflectance of 50% or less in the range of 46 to 50 GHz spans a continuous frequency band of 4.00 GHz. n ・√ε n / λ and d n ・√ε nThe total ε / λ value, d·√ε / λ, was as follows, satisfying formulas (1) and (2): First layer glass plate: d1·√ε1 / λ=3.08...6 times 0.5 + 0.08 Second hollow layer: d2·√ε2 / λ=2.00...4 times 0.5 Third layer glass plate: d3·√ε3 / λ=3.08...6 times 0.5 + 0.08 Fourth hollow layer: d4·√ε4 / λ=2.00...4 times 0.5 Fifth layer glass plate: d5·√ε5 / λ=2.92...6 times 0.5 - 0.08 Total value of the above five layers: d·√ε / λ=13.08...26 times 0.5 + 0.08

[0083] Next, to confirm the frequency characteristics of the reflectance and radio wave transmission power of the obtained window, the maximum reflectance and maximum radio wave transmission power loss were calculated by simulation using the thin film interference calculation formula, as in Example 1. The results are shown in Table 6. It was confirmed that good radio wave transmission was ensured in both cases in the range of 46 to 50 GHz.

[0084] Comparative Example 4 The intermediate frequency in the target communication frequency band (46 to 50 GHz) was 48 GHz, and a window with a triple-glazed structure (a total of five layers) was manufactured by integrating three glass sheets and a frame using the following glass sheets, each having a dielectric constant (ε) of 6.5 at a radio wave wavelength (λ) of 10.7 mm for that frequency: First layer glass sheet thickness (d1) = 7.55 mm, dielectric constant (ε1) = 6.50 Second layer hollow layer thickness (d2) = 12.50 mm, dielectric constant (ε2) = 1.00 Third layer glass sheet thickness (d3) = 7.55 mm, dielectric constant (ε3) = 6.50 Fourth layer hollow layer thickness (d4) = 12.50 mm, dielectric constant (ε4) = 1.00 Fifth layer glass sheet thickness (d5) = 7.55 mm, dielectric constant (ε5) = 6.50

[0085] The frequency range of the obtained window with a reflectance of 50% or less in the range of 46 to 50 GHz spans a continuous frequency band of 1.90 GHz. n ・√ε n / λ and d n ・√ε nThe total value of the ε / λ values, d·√ε / λ, was as follows, and although formula (1) was satisfied, formula (2) was not. First layer glass plate: d1·√ε1 / λ = 3.08...6 times 0.5 + 0.08 Second layer hollow: d2·√ε2 / λ = 2.00...4 times 0.5 Third layer glass plate: d3·√ε3 / λ = 3.08...6 times 0.5 + 0.08 Fourth layer hollow: d4·√ε4 / λ = 2.00...4 times 0.5 Fifth layer glass plate: d5·√ε5 / λ = 3.08...6 times 0.5 + 0.08 Total value of the above five layers: d·√ε / λ = 13.24...26 times 0.5 + 0.24

[0086] Next, to confirm the frequency characteristics of the reflectance and radio wave transmission power of the obtained window, the maximum reflectance and maximum radio wave transmission power loss were calculated by simulation using the thin film interference calculation formula, as in Example 1. The results are shown in Table 6. In all cases, good radio wave transmission was not achieved in the range of 46 to 50 GHz.

[0087] Comparative Example 5 The intermediate frequency in the target communication frequency band (26 to 30 GHz) was 28 GHz, and a window with a triple-layer glass structure (a total of five layers) was manufactured by integrating three glass sheets and a frame using the following glass sheets, each having a dielectric constant (ε) of 6.5 at a radio wave wavelength (λ) of 10.7 mm for that frequency: First layer glass sheet thickness (d1) = 5.97 mm, dielectric constant (ε1) = 6.50; Second layer hollow layer thickness (d2) = 9.86 mm, dielectric constant (ε2) = 1.00; Third layer glass sheet thickness (d3) = 6.09 mm, dielectric constant (ε3) = 6.50; Fourth layer hollow layer thickness (d4) = 10.71 mm, dielectric constant (ε4) = 1.00; Fifth layer glass sheet thickness (d5) = 8.40 mm, dielectric constant (ε5) = 6.50

[0088] The frequency range of the obtained window with a reflectance of 50% or less in the range of 26 to 30 GHz spans a continuous frequency band of 4.19 GHz. n ・√ε n / λ and d n ・√ε nThe total value of the ε / λ values, d·√ε / λ, was as follows, and although formula (1) was satisfied, formula (2) was not. First layer glass plate: d1·√ε1 / λ = 1.42...3 times 0.5 - 0.08 Second layer hollow: d2·√ε2 / λ = 0.92...2 times 0.5 - 0.08 Third layer glass plate: d3·√ε3 / λ = 1.45...3 times 0.5 - 0.05 Fourth layer hollow: d4·√ε4 / λ = 1.00...2 times 0.5 Fifth layer glass plate: d5·√ε5 / λ = 2.00...4 times 0.5 Total value of the above five layers: d·√ε / λ = 6.79...14 times 0.5 - 0.21

[0089] Next, to confirm the frequency characteristics of the reflectance and radio wave transmission power of the obtained window, the maximum reflectance and maximum radio wave transmission power loss were calculated by simulation using the thin film interference calculation formula in the same manner as in Example 1. The results are shown in Table 6. In all cases, good radio wave transmission was not achieved in the range of 26 to 30 GHz.

[0090] Comparative Example 6 The intermediate frequency in the target communication frequency band (47 to 49 GHz) was 48 GHz, and a window with a triple-glazed structure (a total of five layers) was manufactured by integrating three glass sheets and a frame using the following glass sheets, each having a dielectric constant (ε) of 6.5 at a radio wave wavelength (λ) of 6.25 mm for that frequency: First layer glass sheet thickness (d1) = 10.00 mm, dielectric constant (ε1) = 6.50; Second layer hollow layer thickness (d2) = 16.13 mm, dielectric constant (ε2) = 1.00; Third layer glass sheet thickness (d3) = 7.55 mm, dielectric constant (ε3) = 6.50; Fourth layer hollow layer thickness (d4) = 15.63 mm, dielectric constant (ε4) = 1.00; Fifth layer glass sheet thickness (d5) = 9.81 mm, dielectric constant (ε5) = 6.50.

[0091] The frequency range of the obtained window with a reflectance of 50% or less in the range of 47 to 49 GHz spans a continuous frequency band of 2.90 GHz. n ・√ε n / λ and d n ・√ε nThe total value of the ε / λ values, d·√ε / λ, was as follows, and although formula (1) was satisfied, formula (2) was not. First layer glass plate: d1·√ε1 / λ = 4.08...8 times 0.5 + 0.08 Second layer hollow: d2·√ε2 / λ = 2.58...5 times 0.5 + 0.08 Third layer glass plate: d3·√ε3 / λ = 3.08...6 times 0.5 + 0.08 Fourth layer hollow: d4·√ε4 / λ = 2.50...5 times 0.5 Fifth layer glass plate: d5·√ε5 / λ = 4.00...8 times 0.5 Total value of the above five layers: d·√ε / λ = 16.24...32 times 0.5 + 0.24

[0092] Next, to confirm the frequency characteristics of the reflectance and radio wave transmission power of the obtained window, the maximum reflectance and maximum radio wave transmission power loss were calculated by simulation using the thin film interference calculation formula in the same manner as in Example 1. The results are shown in Table 6. In all cases, good radio wave transmission was not achieved in the range of 47 to 49 GHz.

[0093] Comparative Example 7 The intermediate frequency in the target communication frequency band (172 to 182 GHz) was 177.0 GHz, and a window with a double-pane structure (total three-layer structure) was manufactured by integrating two glass plates and a frame using the following soda quartz glass plates, which had a relative dielectric constant (ε) of 5.20 at a radio wave wavelength (λ) of 1.69 mm for that frequency: First layer glass plate thickness (d1) = 3.78 mm, relative dielectric constant (ε1) = 5.20 Second layer hollow layer thickness (d2) = 8.63 mm, relative dielectric constant (ε2) = 1.00 Third layer glass plate thickness (d3) = 3.78 mm, relative dielectric constant (ε3) = 5.20

[0094] The frequency range of the obtained window with a reflectance of 50% or less in the range of 172 to 182 GHz spans a continuous frequency band of 7.40 GHz. n ・√ε n / λ and d n ・√ε nThe total value of the ε / λ values, d·√ε / λ, was as follows, and although formula (1) was satisfied, formula (2) was not. First layer glass plate: d1·√ε1 / λ = 5.09...10 times 0.5 + 0.09 Second layer hollow layer: d2·√ε2 / λ = 5.09...10 times 0.5 + 0.09 Third layer glass plate: d3·√ε3 / λ = 5.09...10 times 0.5 + 0.09 Total value of the above three layers: d·√ε / λ = 15.27...30 times 0.5 + 0.27

[0095] Next, to confirm the frequency characteristics of the reflectance and radio wave transmission power of the obtained window, a thin film interference calculation formula was used to simulate the reflectance and transmission power versus frequency within the target frequency range, creating curves of reflectance and transmission power versus frequency, and calculating the maximum reflectance and maximum radio wave transmission power loss. The results are shown in Table 6. It was confirmed that good radio wave transmission was achieved in both cases within the 172 to 182 GHz range.

[0096]

[0097] Example 25 A window with a triple-pane structure (a total of five layers) was manufactured by assembling three glass sheets and a frame together using the following float glass, which has an intermediate frequency of 28 GHz in the target communication frequency band (26 to 30 GHz) and a relative dielectric constant (ε) of 6.5 at a radio wave wavelength (λ) of 10.7 mm at that frequency, so that each layer satisfied the formulas (1) and (2). First layer glass plate thickness (d1) = 5.97 mm, relative dielectric constant (ε1) = 6.50 ... Selected and used from float glass with a nominal thickness of 6 mm, tolerance of ±0.3 mm (standard product with a deviation of -0.03 mm from the nominal thickness of 6 mm) Second layer hollow layer thickness (d2) = 10.93 mm, relative dielectric constant (ε2) = 1.00 Third layer glass plate thickness (d3) = 6.64 mm, relative dielectric constant (ε3) = 6.50 ... Selected and used from float glass with a nominal thickness of 6.5 mm, tolerance of ±0.3 mm (standard product with a deviation of +0.14 mm from the nominal thickness of 6.5 mm) Fourth layer hollow layer thickness (d4) = 11.04 mm, relative dielectric constant (ε4) = 1.00 Fifth layer glass plate thickness (d5) = 5.97 mm, relative dielectric constant (ε5) = 6.50 ...Selected and used from float glass with a nominal thickness of 6 mm and a tolerance of ±0.3 mm (a standard product with a thickness deviation of -0.03 mm from 6 mm). The float glass used above is a combination selected within the thickness tolerance of the JIS standard.

[0098] The frequency range of the obtained window with a reflectance of 50% or less in the range of 26 to 30 GHz spans a continuous frequency band of 4.00 GHz. n ・√ε n / λ and d n ・√ε n The total d·√ε / λ value was as follows, satisfying formulas (1) and (2): First layer glass plate: d1·√ε1 / λ = 1.42...3 times 0.5 - 0.08 Second layer hollow: d2·√ε2 / λ = 1.02...2 times 0.5 + 0.02 Third layer glass plate: d3·√ε3 / λ = 1.58...3 times 0.5 + 0.08 Fourth layer hollow: d4·√ε4 / λ = 1.03...2 times 0.5 + 0.03 Fifth layer glass plate: d5·√ε5 / λ = 1.42...3 times 0.5 - 0.08 Total value of the above five layers: d·√ε / λ = 6.47...13 times 0.5 - 0.03

[0099] Next, to confirm the frequency characteristics of the reflectance and radio wave transmission power of the obtained window, the maximum reflectance and maximum radio wave transmission power loss were calculated by simulation using the thin film interference calculation formula, as in Example 1. The results are shown in Table 7. It was confirmed that good radio wave transmission was ensured in both cases in the range of 26 to 30 GHz.

[0100] Comparative Example 8 A window with a triple-pane structure (a total of five layers) in which three glass sheets and a frame were integrated was manufactured using the following float glass, which has an intermediate frequency of 28 GHz in the target communication frequency band (26 to 30 GHz) and a relative dielectric constant (ε) of 6.5 at a radio wave wavelength (λ) of 10.7 mm at that frequency. The glass was assembled so that each layer satisfied the formulas (1) and (2). First layer glass plate thickness (d1) = 5.97 mm, relative dielectric constant (ε1) = 6.50 ... Selected and used from float glass with a nominal thickness of 6 mm, tolerance of ±0.3 mm (standard product with a deviation of -0.03 mm from the nominal thickness of 6 mm) Second layer hollow layer thickness (d2) = 10.71 mm, relative dielectric constant (ε2) = 1.00 Third layer glass plate thickness (d3) = 5.97 mm, relative dielectric constant (ε3) = 6.50 ... Selected and used from float glass with a nominal thickness of 6.5 mm, tolerance of ±0.3 mm (standard product with a deviation of -0.03 mm from the nominal thickness of 6.5 mm) Fourth layer hollow layer thickness (d4) = 10.71 mm, relative dielectric constant (ε4) = 1.00 Fifth layer glass plate thickness (d5) = 5.97 mm, relative dielectric constant (ε5) = 6.50 ...Selected and used from float glass with a nominal thickness of 6 mm and a tolerance of ±0.3 mm (a standard product with a thickness deviation of -0.03 mm from 6 mm). The float glass used above is a combination selected within the thickness tolerance of the JIS standard.

[0101] The frequency range of the obtained window in which the reflectance was 50% or less in the range of 26 to 30 GHz spanned a continuous frequency band of 4.00 GHz, and the dn·√εn / λ of each layer and the total value of the dn·√εn / λ were as follows. Although the formula (1) was satisfied, the formula (2) was not satisfied. First glass sheet: d1 · √ε1 / λ = 1.42...3 times 0.5 - 0.08 Second hollow layer: d2 · √ε2 / λ = 1.00...2 times 0.5 Third glass sheet: d3 · √ε3 / λ = 1.42...3 times 0.5 - 0.08 Fourth hollow layer: d4 · √ε4 / λ = 1.00...2 times 0.5 Fifth glass sheet: d5 · √ε5 / λ = 1.42...3 times 0.5 - 0.08 Total value of the above five layers: d · √ε / λ = 6.26...13 times 0.5 - 0.24

[0102] Next, to confirm the frequency characteristics of the reflectance and radio wave transmission power of the obtained window, the maximum reflectance and maximum radio wave transmission power loss were calculated by simulation using the thin film interference calculation formula in the same manner as in Example 1. The results are shown in Table 7. In all cases, good radio wave transmission was not achieved in the range of 26 to 30 GHz.

[0103]

Claims

1. A double-glazed glass having glass plates arranged facing each other with a gap therebetween and a hollow layer formed between the glass plates, and a frame that holds the outer peripheral edge of the double-glazed glass. In the target communication frequency band included in the frequency band of 24 to 300 GHz, the glass has a continuous frequency range in which the reflectance of radio waves is 50% or less, and the d of each glass plate and the hollow layer is n ・√ε n / λ value satisfies the following formula (1), and d n ・√ε n A window in which the sum of the d·√ε / λ values ​​satisfies the following formula (2): n −0.1≦d n ・√ε n / λ ≦ 0.5N n +0.1 (1) (where d n is the thickness of each layer (mm), and ε n is the dielectric constant of each layer at the intermediate frequency of the target communication frequency band, λ is the radio wave wavelength (mm) at said intermediate frequency, N is a natural number from 1 to 100, and n is the number of each layer.) 0.5N-0.2≦d・√ε / λ≦0.5N+0.2 (2) (In the formula, N has the same meaning as above.) Here, the intermediate frequency and its radio wave wavelength λ are any of the values ​​shown in Table 1 below, and the target communication frequency band is a frequency band having a continuous region width of 3 to 17 GHz with the intermediate frequency shown in Table 1 below as a median value.

2. The window according to claim 1, wherein the surface of the glass plate does not have a structure having an uneven shape.

3. The glass sheet is a float glass, and an adjustment mechanism for adjusting the thickness of the hollow layer is further provided, and at least d of the glass sheet is n ・√ε n 3. The window according to claim 1, wherein the / λ value satisfies the following formula (1-1) or (1-2). n −0.1≦d n ・√ε n / λ < 0.5N n (1-1) 0.5N n <d n ・√ε n / λ ≦ 0.5N n +0.1 (1-2) (where d n , ε n , λ, N and n have the same meanings as above.

4. When the d·√ε / λ value exceeds 5, n ・√ε n 3. The window according to claim 1, wherein the d·√ε / λ value satisfies the following formula (3) and the d·√ε / λ value satisfies the following formula (4). n -0.05≦d n ・√ε n / λ ≦ 0.5N n +0.05(3) (in the formula, d n , ε n , λ, N, and n have the same meaning as above.) 0.5N-0.1≦d·√ε / λ≦0.5N+0.1 (4) (wherein N has the same meaning as above.) 5. The glass sheet is a float glass, and an adjustment mechanism for adjusting the thickness of the hollow layer is further provided, and at least d of the glass sheet is n ・√ε n 5. The window according to claim 4, wherein the / λ value satisfies the following formula (3-1) or (3-2). n -0.05≦d n ・√ε n / λ < 0.5N n (3-1) 0.5N n <d n ・√ε n / λ ≦ 0.5N n +0.05 (3-2) (where d n , ε n , λ, N and n have the same meanings as above.

6. A window according to claim 1 or 2, wherein said intermediate frequency and its radio wave wavelength λ are included in said frequency range.

7. The window according to claim 1 or 2, wherein the frequency range has a width of 3 GHz or more.

8. The window according to claim 1 or 2, wherein the target communication frequency band is a communication frequency band for a smartphone terminal or a tablet terminal.

9. A window according to claim 1 or 2, wherein the insulating glass is arranged at intervals via a spacer which is an adjustment mechanism for adjusting the thickness of the hollow layer.

10. The window according to claim 1 or 2, wherein the glass plate is float glass with an inorganic or organic film, or laminated glass.

11. The window according to claim 7, wherein the inorganic or organic film is a low emissivity (Low-E) film.

12. A method for manufacturing a window as claimed in claim 1, comprising the steps of: preparing two or more pieces of float glass which satisfy formula (1), where λ is the radio wave wavelength of an intermediate frequency in a target communication frequency band included in the 24 to 300 GHz frequency band; arranging the two or more pieces of float glass prepared opposite each other at a predetermined distance via an adjustment mechanism which adjusts the thickness of the hollow layer, and assembling the pieces of float glass so that the hollow layers formed between each piece of float glass and between the pieces of float glass satisfy formulas (1) and (2), to obtain a double-glazed window; integrating the obtained double-glazed window with a frame to obtain a window; and confirming that the reflectance of radio waves in the target communication frequency band for the obtained window is in a frequency range of 50% or less.

13. The method for manufacturing a window according to claim 12, wherein in the step of obtaining the double glazing, the float glass satisfies the following formula (1-1) or (1-2): n −0.1≦d n ・√ε n / λ < 0.5N n (1-1) 0.5N n <d n ・√ε n / λ ≦ 0.5N n +0.1 (1-2) (where d n , ε n , λ, N and n have the same meanings as above.

14. The method for manufacturing a window according to claim 12, wherein the frequency range is a continuous frequency band of 3 GHz or more.

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