Fresnel zone plate lens, window glass with integrated Fresnel zone plate lens, and window glass with Fresnel zone plate lens

Abstract

The present invention is a Fresnel zone plate lens which improves radio wave reception sensitivity by suppressing the radio wave shielding action of a conductive film while reducing an installation space, and said Fresnel zone plate lens has a base 10, transmission sections T which are formed in a conductive film 20 on the base 10 and allow radio waves to pass therethrough, and shielding sections S which are formed in the conductive film 20 on the base 10 and have a lower degree of radio wave transmittance than the transmission sections T. The transmission sections T and the shielding sections S are disposed alternatingly in concentric circles form a Fresnel zone plate lens (FZPL) 2 that focuses, on a focal point, radio waves having a first wavelength λ1. The transmission sections T have a frequency selective surface (FSS) structure which allows radio waves having the first wavelength λ1 to pass therethrough.

Description

Technical Field

[0001] The present invention relates to a Fresnel zone plate lens, a window glass integrated with a Fresnel zone plate lens, and a window glass with a Fresnel zone plate lens.

Background Art

[0002] In the mobile communication standard called the fifth generation (5G), a band less than 6 GHz called "sub-6" and a band of 24.2 to 29.5 GHz called the "millimeter wave band" are included. Among these radio waves, especially in the millimeter wave band, the attenuation at boundaries such as glass and walls is large, making it difficult for radio waves to penetrate from the outside to the inside of a room.

[0003] In addition, a Low-E film may be provided on window glass for the purpose of heat insulation or the like. However, since the Low-E film is made of a conductive film, in window glass provided with the Low-E film, the radio waves in the millimeter wave band and the Sub-6 band are blocked by the Low-E film, preventing the penetration of radio waves from the outside to the inside of the room.

[0004] Therefore, in order to allow radio waves in the millimeter wave band to penetrate from the outside to the inside of a room even for a window provided with a Low-E film, in Patent Document 1, as shown in FIG. 1, a radio wave lens called a Fresnel zone plate lens (FZPL) is provided inside a window provided with the Low-E film, and by focusing the radio waves on a single point inside the room, it has been proposed to improve the reception sensitivity of radio waves inside the room.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the method described in Patent Document 1, even if an FZPL is installed on the indoor side, the radio wave blocking effect of the conductive Low-E film remains on the outside, resulting in a low improvement in reception sensitivity. In addition, since the FZPL is placed away from the window, a large installation space is required.

[0007] Therefore, in view of the above circumstances, the present invention aims to provide a Fresnel zone plate lens that can reduce the installation space and improve the reception sensitivity of radio waves by suppressing the radio wave blocking effect of the conductive film. [Means for solving the problem]

[0008] To solve the above problems, in one aspect of the present invention, Substrate and, A conductive film formed on the substrate, which transmits radio waves, It has a conductive film formed on the substrate and a shielding portion which has a lower degree of radio wave transmission than the transparent portion, A Fresnel zone plate lens (FZPL) that focuses radio waves of a first wavelength λ1 at a focal point by having the transmitting portion and the shielding portion arranged concentrically and alternately, The aforementioned transmission portion is an FSS (Frequency Selective Plate) structure that transmits radio waves of the first wavelength λ1. We provide Fresnel zone plate lenses.

[0009] Furthermore, in another aspect of the present invention, A glass plate on which a Low-E film is formed, The Fresnel zone plate lens includes a transparent portion formed on the glass plate in an exposed area where no Low-E film exists, which transmits radio waves, and a shielding portion formed on the Low-E film on the glass plate, which transmits radio waves less than the transparent portion, and the transparent portion and the shielding portion are arranged concentrically and alternately to focus radio waves of a first wavelength λ1 at a focal point. The Fresnel zone plate lens is formed on the same plane as the Low-E film outside the Fresnel zone plate lens area. We provide window glass with an integrated Fresnel zone plate lens.

Advantages of the Invention

[0010] According to one aspect, the Fresnel zone plate lens can reduce the placement space, suppress the blocking effect of radio waves by the conductive film, and improve the radio wave reception sensitivity.

Brief Description of the Drawings

[0011] [Figure 1] Perspective view showing the arrangement configuration of FZPL and Low-E window glass in the conventional example. [Figure 2] Perspective view of the FZPL integrated window glass in the first embodiment of the present invention. [Figure 3] Side cross-sectional explanatory view of the FZPL integrated window glass in the first embodiment of the present invention. [Figure 4] Diagram showing an example of the configuration of FZPL. [Figure 5] Explanatory diagram of a plurality of examples of the front configuration of FZPL. [Figure 6] Explanatory diagram of the FZPL integrated window glass of the first configuration example of the first embodiment. [Figure 7] Explanatory diagram of the FZPL integrated window glass of the second configuration example of the first embodiment. [Figure 8] Explanatory diagram of the FZPL integrated window glass of the third configuration example of the first embodiment. [Figure 9] Diagram showing an example of a photograph of the FZPL integrated window glass of the first configuration example, the second configuration example, and the third configuration example. [Figure 10] Perspective view of the window glass with FZPL in the second embodiment of the present invention. [Figure 11] Side cross-sectional explanatory view of the window glass with FZPL in the first configuration example of the second embodiment. [Figure 12] Cross-sectional view of the window glass with FZPL of the second configuration example of the second embodiment. [Figure 13] Cross-sectional view of the window glass with FZPL of the third configuration example of the second embodiment. [Figure 14] Cross-sectional view of the window glass with FZPL of the first modification of the second embodiment. [Figure 15] A diagram showing an analysis model that mimics Comparative Example 1, Comparative Example 2, and the first configuration example in Example 1. [Figure 16] Graphs showing the simulated gains for analysis model 1, analysis model 2, and analysis model 3 in Figure 15. [Figure 17] In Example 2, a table shows the various characteristics of analysis models 4, 5, and 6, which are modeled after the first, second, and third configuration examples. [Figure 18] Figure 17 shows graphs illustrating the gain near the focal point when simulating analysis models 4, 5, and 6 with a set wavelength of 28 GHz. [Figure 19] Figure 7, 8, 9, and 10 show the analysis models 7, 8, 9, and 10 in Example 3, where the state of the Low-E film is changed. [Figure 20] Graphs showing the transmission characteristics simulated for analysis models 7-10 in Figure 19. [Figure 21] Table showing various characteristics of analysis models 11 and 6, which mimic the first and third configuration examples in Example 4. [Figure 22] Graphs showing the transmission characteristics simulated for analysis models 11 and 6 in Figure 21. [Figure 23] A table summarizing the film retention rate, solar heat gain coefficient, and performance of the first, second, and third configurations of Example 5, and Comparative Example 1. [Figure 24] Graphs showing the solar heat gain coefficients for two Low-E film layers and three Low-E film layers in Figure 23. [Modes for carrying out the invention]

[0012] Embodiments of the present invention will be described below with reference to the drawings. For ease of understanding, the scale of each component in the drawings may differ from the actual scale. In directions such as parallel, right angles, orthogonal, horizontal, vertical, up and down, and left and right, deviations are permitted to the extent that they do not impair the function and effect of the embodiment. The shape of the corners is not limited to right angles, but may be rounded in an arc shape. Parallel, right angles, orthogonal, horizontal, and vertical directions may include approximately parallel, approximately right angles, approximately orthogonal, approximately horizontal, and approximately vertical directions.

[0013] In this specification, a three-dimensional Cartesian coordinate system with three axes (X-axis, Y-axis, and Z-axis) is used, where the width direction of the wall is the X-axis direction, the height direction of the wall is the Z-axis direction, and the thickness direction of the wall is the Y-axis direction. The direction from the bottom of the wall upwards is the +Z-axis direction, and the opposite direction is the -Z-axis direction. The direction from the outdoors to the indoors is the +Y-axis direction, and the opposite direction is the -Y-axis direction. In the following description, the +Z-axis direction may be referred to as "up" and the -Z-axis direction as "down," the +Y-axis direction may be referred to as "indoor side," and the -Y-axis direction may be referred to as "outdoor side."

[0014] The X-axis, Y-axis, and Z-axis directions represent directions parallel to the X-axis, Y-axis, and Z-axis, respectively. The X-axis, Y-axis, and Z-axis directions are mutually orthogonal. The XY plane, YZ plane, and ZX plane represent virtual planes parallel to the X-axis and Y-axis, virtual planes parallel to the Y-axis and Z-axis, and virtual planes parallel to the Z-axis and X-axis, respectively.

[0015] Furthermore, in the following explanation, when we refer to "millimeter waves" or "millimeter wave band," we mean the quasi-millimeter wave band of 24 GHz to 30 GHz in addition to the frequency band of 30 GHz to 300 GHz. "Radio waves" are a type of electromagnetic wave, and generally, electromagnetic waves below 3 THz are called radio waves. In the following, electromagnetic waves radiated from outdoor base stations or relay stations will be referred to as "radio waves," and when referring to electromagnetic waves in general, we will use the term "electromagnetic waves." In the diagrams, the same elements may be given the same symbols to omit redundant explanations.

[0016] <First Embodiment> Figure 2 is a perspective view of the FZPL integrated window glass in the first embodiment of the present invention. Figure 3 is a side cross-sectional view of the FZPL integrated window glass in the first embodiment of the present invention.

[0017] As shown in Figures 2 and 3, the Fresnel Zone Plate Lens (hereinafter referred to as FZPL) according to the first embodiment of the present invention is integrally formed with a glass plate 10 as a window pane 30. The glass plate 10 on which the FZPL is integrally formed as a window pane 30 is not limited to a window pane of a building supported by a wall 80, but may also be the roof of a shelter at a bus stop or station platform, the rear window of a car, etc.

[0018] Generally, building walls act as shields for millimeter-wave radio waves, either blocking them completely or significantly attenuating them. Therefore, radio waves emitted from outdoor base stations (BS) enter the building through windows rather than walls. Once the radio waves pass through the windows, they continue to travel in a straight line. As a result, areas inside a building that are not within the line of sight (LOS) become dead zones with poor communication conditions, making it difficult to receive radio waves.

[0019] Therefore, in the window glass of this embodiment, as shown in Figures 2 and 3, the FZPL1, which functions as a phase adjustment plate, a radio wave focuser, and a frequency selection plate, is integrally formed with the glass plate 10. In this embodiment, the FZPL1 is composed of a homogeneous residual portion 22 which is a shielding portion and an exposed portion 23 which is a transparent portion where the outer surface 11 of the glass plate 10 is exposed.

[0020] As a result, the window glass 30, into which the FZPL1 is integrally formed, focuses the radio waves radiated from the outdoor base station BS and incident on the window glass 30 to a predetermined focal point F, allowing indoor wireless devices such as smartphones, repeaters, and CPE (Customer Premises Equipment) 90 to receive the radio waves.

[0021] Generally, as the frequency increases, propagation losses due to reflection and diffraction increase, making it easier for such dead zones to occur. Therefore, the frequency of radio waves selectively focused by the FZPL of the present invention is preferably in the millimeter-wave band, such as that used in fifth-generation mobile communication systems (5G).

[0022] Furthermore, in the mobile communication standard known as fifth generation (5G), some countries are allocated two or more frequency bands, including at least two bands that include the 24.2-29.5 GHz band known as the "millimeter wave band" and the band below 6 GHz known as the "sub-6" band. Even when the millimeter wave band, which has a high attenuation rate, is used as the design wavelength for focusing in FZPL, it is desirable to focus the target radio wave without interfering with the Sub-6 band (radio waves with frequencies lower than the target radio wave), which are radio waves other than the frequency to be focused.

[0023] In this example, the first frequency radio wave, which is the target radio wave of FZPL (the radio wave to be focused), is described as being in the millimeter wave band, and the second frequency radio wave, which is the radio wave to be transmitted, is described as being in the Sub-6 band. However, as another example of the present invention, the target radio wave may be set to the Sub-6 band, LTE (Long Term Evolution), LTE-A (LTE-Advanced), UMB (Ultra Mobile Broadband), IEEE802.11 (Wi-Fi®), IEEE802.16 (WiMAX®), IEEE802.20, UWB (Ultra-Wideband), Bluetooth®, LPWA (Low Power Wide Area), etc., and the second frequency radio wave may be set to a lower frequency than the first frequency radio wave.

[0024] Referring to Figure 2, the window glass 30 according to the first embodiment of the present invention is Low-E glass, in which a transparent conductive film, the Low-E film (Low Emissivity Coating) 20, is coated on the surface of the glass plate 10. Low-E glass, also known as low-emissivity glass, is window glass coated with a transparent conductive film (Low-E film), which is a coating layer having a heat-reflective function. In this example, the Low-E film 20 is coated on the outdoor surface (outer surface) 11 of the glass plate 10.

[0025] In this embodiment, the Low-E film 20 has an out-of-zone Low-E film 21 where the FZPL1 is not formed, and a homogeneous residual portion 22 that constitutes the shielding portion of the FZPL1. By processing the Low-E film 20 in this way, the Fresnel zone plate lens 1 is directly formed on the Low-E film 20, and when the Low-E film 20 is coated onto the glass plate 10, the window glass becomes a window glass in which the FZPL is integrally formed.

[0026] In other words, the FZPL of this embodiment is formed integrally with the window glass, which is Low-E glass, on the same plane as the Low-E film by processing a portion of the Low-E glass that is coated on one surface of the glass plate.

[0027] The glass plate 10 that makes up the window glass 30 can be any glass that is generally available, such as soda-lime glass, alkali-free glass, aluminosilicate glass, Pyrex® glass, or quartz glass.

[0028] Furthermore, the Low-E film 20 coated on the glass plate 10 is composed of a multilayer film consisting of, for example, one or more silver layers, which are metals that exhibit low radiation performance, and a protective metal oxide layer. The Low-E film 20 is a permeable film, but is not limited to being colorless and transparent; it may also be colored and transparent. For example, a colored and transparent Low-E film 20 may appear slightly colored, such as green, silver, blue, or blue-gray, when viewed from a distance.

[0029] Furthermore, while Figures 2 and 3 show an example where the window glass 30 is a single-layer glass composed of one glass plate, the window glass to which the Low-E film with partially formed FZPL1 is coated may be a double-layer glass with two glass plates facing each other with a space in between, or a double-layer glass with three or more plates.

[0030] Figures 2 and 3 show an example in which the FZPL1 is directly formed on the outdoor side of the window glass 30 by processing the Low-E film 20 coated on the outdoor side of the glass plate. However, the FZPL may also be directly formed on the indoor side by processing the Low-E film coated on the indoor side of the glass plate. Furthermore, if the window glass is double-glazed, the Low-E film may be coated on the inner surface where the two glass plates are arranged facing each other, in which case the FZPL1 will be formed on the inner surface where the two glass plates are arranged facing each other. In either case, in the FZPL-integrated window glass of this embodiment, the FZPL is formed on the same plane as the surface on the glass plate to which the Low-E film is coated.

[0031] In this embodiment, the height from the ground of the FZPL1, which is integrally configured on the window glass 30 of the building, is preferably 1 to 30 m, and particularly preferably 2 to 10 m, in terms of radio wave efficiency.

[0032] In this embodiment, an example was described in which FZPL is directly formed on window glass by processing a Low-E film coated on a glass plate. However, in other examples of this embodiment, FZPL may be directly formed on window glass by processing another conductive film coated on a glass plate. The conductive film on which FZPL is formed by processing a portion may be, for example, a colored conductive film for advertising coated on a glass plate. In addition, transparent conductive films such as zinc oxide (ZnO), tin oxide (SnO2), tin-doped indium oxide (ITO), indium oxide-tin oxide (IZO), or metal nitrides such as titanium nitride (TiN) or chromium nitride (CrN) may also be used.

[0033] Alternatively, the Low-E film or the conductive film mentioned above may be formed on the glass plate by adhesion instead of coating.

[0034] <Basic configuration of a Fresnel lens> Here, the basic configuration common to the FZPL of the present invention will be described. Figure 4 is a diagram showing an example of the configuration of the FZPL. In Figure 4, only the shielding parts S1, S2, S3, S4, and S5 of the FZPL1 are shown, and the configuration corresponding to the glass plate is omitted. Figure 4(a) is a plan view showing the FZPL1, and Figure 4(b) is a perspective view showing the FZPL1 and the focal point. In Figure 4, C indicates the center of the FZPL1, F indicates the focal point, and A indicates the central axis. The central axis A is an axis that passes through the center C of the FZPL1 and is parallel to the Y axis. The focal point F is located on the central axis A. The distance between the center C and the focal point F is denoted as the focal length D.

[0035] The basic configuration of an FZPL involves periodically arranging regions that transmit and reflect (shield) radio waves according to the wavelength of the radio wave to be focused. More specifically, in an FZPL1, annular shielding sections (also called conductor sections or reflectors) S (S1~S6) and annular transmitting sections T (T1~T6) are alternately arranged concentrically around a central C.

[0036] The shielding sections S1 to S6, which transmit less radio waves than the transmitting section T, are Fresnel annular bands positioned relative to the center C at a predetermined frequency f based on the wavelength λ and focal length D. In the example of FZPL shown in Figure 4, the shielding sections S1 to S6 and the transmitting sections T1 to T6 are each sixfold, thus forming 12th-order Fresnel annular bands.

[0037] Here, since the shielding portions S1 to S6 are all annular conductors, they have an inner end (inner circumferential end) and an outer end (outer circumferential end). The inner circumferential end is a circumferential end located on the inner circumference of the annular conductor, and the outer circumferential end is a circumferential end located on the outer circumference of the annular conductor.

[0038] The radial distance (inner radius) between the inner circumferential end of shielding portion S1 and the center C is half the inner diameter of shielding portion S1, and the radial distance (outer radius) between the outer circumferential end of shielding portion S1 and the center C is half the outer diameter of shielding portion S1. This is also true for shielding portions S1 to S6.

[0039] Let r1 be the radial distance (inner radius) between the inner circumference end of shielding part S1 and the center C, and r2 be the radial distance (outer radius) between the outer circumference end of shielding part S1 and the center C. Let r3 be the radial distance (inner radius) between the inner circumference end of shielding part S2 and the center C, and r4 be the radial distance (outer radius) between the outer circumference end of shielding part S2 and the center C. Let r5 be the radial distance (inner radius) between the inner circumference end of shielding part S3 and the center C, and r6 be the radial distance (outer radius) between the outer circumference end of shielding part S3 and the center C. Let r7 be the radial distance (inner radius) between the inner circumference end of shielding part S4 and the center C, and r8 be the radial distance (outer radius) between the outer circumference end of shielding part S4 and the center C. Let r9 be the radial distance (inner radius) between the inner circumference end of shielding part S5 and the center C, and r10 be the radial distance (outer radius) between the outer circumference end of shielding part S5 and the center C. Let r11 be the radial distance (inner radius) between the inner circumferential end of the shielding portion S6 and the center C, and let r12 be the radial distance (outer radius) between the outer circumferential end of the shielding portion S6 and the center C.

[0040] In FZPL1, let rk (k = an integer from 1 to 12) be the distances r1 to r12 to the Fresnel rings, and using the focal length D of FZPL1 and the wavelength λ of the radio wave at frequency f that FZPL1 focuses on, the following equation (1) holds.

[0041]

number

[0042]

number

[0043] Thus, of the N annular shielding parts S1 to S6 of FZPL1, the m-th shielding part (where m is any integer from 1 to N (where N is an integer greater than or equal to 3) from the inside has an inner radius k = 2m-1 and an outer radius k = 2m, and if the distance between the inner radius 2m-1 and the outer radius 2m is represented as the radial distance rk, then equation (2) holds for the radial distance rk. The radial distance rk is assigned sequentially from the inside as r1, ..., rk (where k is an even number greater than or equal to 4) to the radial distance between the inner and outer edges of each shielding part and the center C. Of the radial distances rk, the radial distances rk with an odd k are the distances with respect to the inner edges, and the radial distances rk with an even k are the distances with respect to the outer edges.

[0044] The positions of the shielding sections S1 to S6 relative to the center C are determined by the positions of the inner and outer edges. The positions of the inner and outer edges of the shielding sections S1 to S6 are determined by equation (2), which includes the wavelength λ of the radio wave at a predetermined frequency f that FZPL1 focuses, the focal length D of FZPL1, and the value k. Therefore, the positions of the shielding sections S1, S2, S3, S4, S5, and S6 are determined based on the wavelength λ and focal length D at a predetermined frequency f.

[0045] The shielding sections S1 to S6 refract the radio waves that have passed through FZPL1 toward the focal point F, and also block the radio waves that are out of phase at the focal point F, thereby focusing the radio waves of a predetermined frequency f to the focal point F with a focal length D through a lens effect.

[0046] In FZPL, the radial width of the shielding becomes narrower as you move away from the shielding S1 on the central C side, and the distance between adjacent radially adjacent shielding parts (S5, S6) on the outer side becomes narrower than the distance between adjacent radially adjacent shielding parts (S1, S2) on the central C side. Also, the further away the shielding is from the shielding S1 on the central C side, the greater the angle at which the radio waves are focused toward the focal point F.

[0047] In FZPL, the value of the radial distance rk k is treated as the order k from the center C side. In FZPL, it has been found that including shielding areas with low k values ​​closer to the center C (towards the center), such as shielding area S1 specified by k=1 and 2, and shielding area S2 specified by k=3 and 4, is effective in obtaining a high electric field strength at the focal point F. In other words, radio waves passing near shielding areas S1 and S2 of FZPL contribute more to the electric field strength at the focal point F than radio waves passing near shielding areas S3 to S6.

[0048] As mentioned above, Fresnel zone lenses with this configuration achieve their lens function by blocking all waves except those in phase at the focal point. Furthermore, the radius increases with lower frequencies (longer wavelengths) even with the same number of zones. A larger number of zones allows for the collection of more radio waves.

[0049] Figure 5 shows several examples of the front configuration of the FZPL. Figure 5(a) shows FZPL1, where the center is a transparent portion, and Figure 5(b) shows FZPL1α, where the center is a shielding portion. In Figure 4, an example of a Fresnel zone plate lens where the center is a transparent portion was described as in Figure 5(a), but the front configuration of the Fresnel zone plate lens of the present invention may also have a shielding portion S in the center, as shown in Figure 5(b).

[0050] Fresnel zone plate lenses form a so-called metasurface. A "metasurface" refers to an artificial surface that controls the transmission and reflection properties of incident electromagnetic waves. By controlling at least one of the phase and amplitude of the electromagnetic waves incident on the shielding portion (conductor portion), it is possible to realize optical properties that do not exist in nature. Fresnel zone plate lenses can transmit, reflect, or focus (concentrate) incident electromagnetic waves in a desired direction.

[0051] In Figures 4 and 5, an example of a first configuration in the FZPL is shown in which the shielding portion is a homogeneous (uniform, solid) conductive portion without holes or gaps, and the permeable portion is a hollowed-out portion without a conductor. However, in the FZPL of the present invention, the shielding portion does not have to be homogeneous, and a conductive portion with grooves may remain in the permeable portion. The details of the FZPL of the first embodiment of the present invention will be described below.

[0052] <First Configuration Example of the First Embodiment> Figure 6 is an explanatory diagram of the FZPL integrated window glass 30 of the first configuration example of the first embodiment.

[0053] In this configuration example, in FZPL1, the shielding portions S1, S2, and S3 are formed by homogeneous residual portions 22 in which the Low-E film 20 remains uniformly without holes or gaps, similar to the out-of-region Low-E film 21 where FZPL is not formed. On the other hand, the transparent portions T1, T2, T3, and T4 are formed by exposed portions 23 in which the Low-E film is cut out and the outer surface 11 of the glass plate 10 is exposed.

[0054] In other words, in the FZPL1 constructed with the Low-E film 20 of this configuration example, the film is peeled off (decoated) in the areas where the first wavelength of radio waves are to be transmitted, while the film remains uniformly in the areas where reflection (shielding) is to be performed. Therefore, in this configuration example, since the FZPL can be formed by decoating only the partially transparent areas, an FZPL integrated window glass can be realized with simple processing.

[0055] Furthermore, in this configuration example, since the FZPL is formed by processing a portion of the Low-E film, as shown in Figure 1, there is no Low-E film that interferes with radio waves relative to the FZPL. Therefore, without being affected by radio wave blocking, the FZPL, which is integrated with the window glass, can focus radio waves of the first wavelength through the shielding portion S and the transmitting portion T indoors, and transmit radio waves of the second wavelength through the transmitting portion T.

[0056] Furthermore, because the window glass and FZPL are integrally constructed, there is no need for space on the inside of the window glass to place the FZPL, compared to a configuration where the FZPL is placed separately from the window glass.

[0057] <Second configuration example of the first embodiment> Figure 7 is an explanatory diagram of the FZPL integrated window glass 30A of the second configuration example of the first embodiment.

[0058] In the first configuration example of FZPL, the transparent portion has no Low-E film (decoated), while the shielding portion remains uniformly intact. Therefore, the decoating may reduce the heat shielding performance of the Low-E glass in the transparent portion. In addition, a contrast is created between the decoated portion with no film and the uniformly remaining film portion, and when viewed from a certain distance, the annular shape of the shielding portion S of FZPL may become visible, potentially degrading the appearance.

[0059] Therefore, in the FZPL2 configuration example, the transmission sections T1, T2, T3, and T4 are formed by a Low-E film processed to a Frequency Selective Surface (FSS) structure. Figure 7 shows an example where the Low-E film with an FSS structure constituting the transmission sections T1, T2, T3, and T4 has a fine grid shape (mesh shape, a unit shape in which the mesh is arranged in a grid) with small grid sections 24.

[0060] In Figure 7, the transmission section T is shown as an example of a grid with vertical and horizontal slits to select the frequency to be transmitted. However, the shape of the FSS is not limited to this configuration, as long as it transmits both millimeter waves and Sub6 bands. For example, it may have slits in only one direction, either vertical or horizontal, in the direction of the polarization to be transmitted. Alternatively, it may have slits at an angle of ±45°. Furthermore, it may have an FSS structure with slits such as a roughly cross-shaped Jerusalem cross, or in which the Jerusalem cross shape remains as floating islands.

[0061] Furthermore, in this configuration example, the shielding portions S1, S2, and S3 are formed by homogeneous residual portions 22, where the Low-E film 20A remains uniformly, similar to the out-of-region Low-E film 21 other than FZPL, as shown in Figure 6. Therefore, the Low-E film 20A in this configuration example has an out-of-region Low-E film 21 where FZPL2 is not formed, a homogeneous residual portion 22 that constitutes the shielding portion of FZPL2, and a small grid portion 24 that constitutes the transmission portion.

[0062] In this configuration example, the transmission section T (T1, T2, T3, T4) of the FZPL2 realizes an FSS structure by a unit shape with slits arranged in a grid pattern in two directions. Preferably, the circumference of the unit shape of the FSS structure of the transmission section T is 1 / 100 to 1 times the first wavelength λ1 and 1 / 600 to 1 / 6 times the second wavelength λ2. With this configuration, the transmission section T can selectively transmit both the millimeter wave band (e.g., 28 GHz), which is the first wavelength λ1, and the Sub-6 band (e.g., 3.3 GHz), which is the second wavelength λ2, which is lower than the first wavelength.

[0063] Therefore, with the FZPL2, which is integrated with the window glass, the shielding part S and the transmitting part T can focus radio waves of the first wavelength indoors, and the transmitting part T can transmit radio waves of the second wavelength.

[0064] In this configuration example, with FZPL2, a Low-E film remains in a grid pattern on the small grid sections 24 that constitute the transparent section T. Therefore, the boundary between the annular shielding section S and the transparent section T of FZPL2 is less visible than in the first configuration example, and the decrease in heat shielding performance can be suppressed.

[0065] <Third Configuration Example of the First Embodiment> Figure 8 is an explanatory diagram of the FZPL integrated window glass 30B of the third configuration example of the first embodiment.

[0066] In the first and second configuration examples, the homogeneous residual portion 22 of the FZPL reflects frequencies other than those to be focused, which may slightly obstruct the intrusion of radio waves of a second wavelength, which are radio waves other than the desired frequency.

[0067] Therefore, in this configuration example, in the FZPL, the shielding sections S1, S2, and S3 are formed by a Low-E film processed into a frequency-selective surface FSS structure, which has different characteristics from the transmission section. In this example, the FSS structure of the shielding section S is formed by a grid shape (mesh shape) created by vertical and horizontal slits, and is shown to be formed by a large grid section 25, which has a larger repeating unit shape than the transmission section T.

[0068] Furthermore, in this configuration example, the permeable portions T1, T2, T3, and T4 are formed by a small grid portion 24, which is a Low-E film processed into a lattice-like FSS structure, similar to the second configuration example.

[0069] More specifically, the shielding section S realizes an FSS structure by a unit shape with slits arranged in a grid pattern in two directions. Preferably, the perimeter (sum of the four sides of the square) of the unit shape of the FSS structure of the shielding section S is 1 / 4 to 2 times the first wavelength λ1 and 1 / 25 to 1 / 4 times the second wavelength λ2.

[0070] In Figure 8, the shielding section S is shown as a grid with vertical and horizontal slits to allow selection of the frequency to be transmitted. However, the shape of the FSS is not limited to this configuration, as long as it transmits the Sub-6 band and shields the millimeter wave band. For example, it may have slits in only one direction, either vertical or horizontal, in the direction of the polarization to be transmitted. Alternatively, it may have slits at an angle of ±45°. Furthermore, it may have an FSS structure with slits such as a roughly cross-shaped Jerusalem cross, or in which the Jerusalem cross shape remains as floating islands.

[0071] Furthermore, the transparent section T, similar to the second configuration example, realizes an FSS structure by a unit shape with slits arranged in a grid pattern in two directions, and it is preferable that the circumference of the unit shape is 1 / 100 to 1 times the first wavelength λ1 and 1 / 600 to 1 / 6 times the second wavelength λ2.

[0072] In this configuration example, the Low-E film 20B has an out-of-region Low-E film 21 where FZPL3 is not formed, a large grid portion 25 that constitutes the shielding portion of FZPL3, and a small grid portion 24 that constitutes the transmission portion. Therefore, in the FZPL3 of this configuration example, since the Low-E film remains in a grid pattern in both the transmission portion and the shielding portion, the boundary between the annular shielding portion S and the transmission portion T of FZPL3 becomes less visible than in the first configuration example.

[0073] In this configuration example, both the transmission section T and the shielding section S have a grid-like FSS structure. The transmission section T is configured to transmit both radio waves of the first frequency (for example, the millimeter-wave band with a center frequency of 28 GHz) and radio waves of the second frequency (for example, the Sub-6 band with a center frequency of 3.3 GHz). On the other hand, the shielding section S is configured to block radio waves of the first frequency but transmit radio waves of the second frequency.

[0074] Therefore, in this configuration example, by using an FSS configuration for both the transparent and shielding parts, it is possible to convert Low-E glass to FZPL without compromising the heat shielding properties and aesthetics of the Low-E film, and without interfering with radio waves other than the frequency to be focused. With this setting, in the third configuration example, if one of the frequencies to be focused by FZPL (the first frequency) is set to the millimeter wave band (for example, 6GHz to 100GHz), then in the other frequency band, the Sub6 band (400MHz to 6GHz), an improvement in the reception sensitivity of millimeter wave radio waves can be expected without causing shielding of Sub6 band radio waves in the shielding part S.

[0075] Figure 9 shows images of the FZPL integrated window glass for the first, second, and third configurations, taken from a distance of 1.0 m.

[0076] As an example of a window glass used as the subject of photography, the glass plate 10 had dimensions of 300mm x 300mm, a thickness of 0.55mm, and an FZPL focal length D=300mm. The Low-E coating used consisted of two layers of Ag film. In addition, in the FZPL integrated window glass 30, 30A, and 30B shown in Figure 9, the out-of-bounds Low-E coating 21 was not applied to any of them.

[0077] In the first configuration example, FZPL1, a Fresnel order of 12 was used, while in the second and third configuration examples, FZPL2 and FZPL3, a Fresnel order of 11 was used.

[0078] As shown in Figure 9(a), in the FZPL integrated window glass 30 of the first configuration example, the annular shielding portion S of FZPL1 is visible from a distance of 1.0 m. As shown in Figures 9(b) and 9(c), in the FZPL integrated window glass 30A and 30B of the second and third configuration examples, the shielding portion S and the transparent portion T are difficult to see.

[0079] <Second Embodiment> In the above embodiment, an example was described in which the FZPL is formed on the same plane as the Low-E film coated on the window glass. However, the FZPL may also be attached to the glass plate by bonding it to the glass plate with an adhesive layer, without being integrally formed with the glass plate.

[0080] Figure 10 is a perspective view of the FZPL-equipped window glass (laminated window glass) 300 in the second embodiment of the present invention. Figure 11 is a side cross-sectional explanatory view of the FZPL-equipped window glass 300 in the first configuration example of the second embodiment.

[0081] In this embodiment, the Fresnel zone plate lens (hereinafter referred to as FZPL) 4, which is a laminate in which a Fresnel zone plate lens layer is formed on a substrate 50 by a Low-E film 60, is not integrally formed with the glass but is attached to the glass plate 10 by an adhesive layer 40.

[0082] Furthermore, in the window glass 300 of this embodiment, the region of the Low-E film 20C coated on the glass plate 10C that faces the FZPL4 is an opening region 26.

[0083] In this embodiment, the FZPL4 comprises a substrate 50 having a first main surface (indoor side surface) 51 and a second main surface 52 facing each other, and a Low-E film 60 provided on the first main surface 51 of the substrate 50. Here, "main surface" refers to a surface perpendicular to the thickness direction of the substrate 50. The substrate 50 transmits radio waves incident from the second main surface 52 to the first main surface 51. The Low-E film 60 may also be provided on the second main surface 52 of the substrate 50.

[0084] The substrate 50 is made of any material that is transparent to radio waves of a first frequency, which is the operating frequency of the FZPL4, and also transparent to radio waves of a second frequency, and that can support the Low-E film 60. "Transparent" means that the transmittance is 40% or more, preferably 50% or more, more preferably 60% or more, and even more preferably 70% or more. As an example, a resin substrate is used for the substrate 50. As a resin material that satisfies the above conditions, polyethylene terephthalate (PET), acrylic resins such as polymethyl methacrylate, cycloolefin resins, polycarbonate resins, etc. can be used. The substrate 50 is a disc-shaped substrate having the same outer edge as the outer edge of the FZPL4. Furthermore, if the substrate is a resin, a plate-shaped, sheet-shaped, or film-shaped resin can be used.

[0085] The conductive portion, the homogeneous pattern 61, is composed of a homogeneous Low-E film 60 without holes or gaps, just like the Low-E film 20C on the glass plate 10C.

[0086] The adhesive layer 40 is made of any adhesive material that is transparent to the first frequency radio waves, which are the operating frequencies of the FZPL4, and to the second frequency radio waves, and that can bond the glass plate 10C and the substrate 50 of the FZPL4. The "transparent" of the adhesive layer 40 is the same as the "transparent" of the substrate 50.

[0087] In this embodiment, for example, the laminated FZPL4 is formed separately from the glass plate 10C and attached to the glass plate 10C with an adhesive layer 40. Therefore, for example, the function of FZPL can be added to existing Low-E glass by decoating the Low-E film on the opposite side of the FZPL4 and attaching the FZPL4.

[0088] In the second embodiment, the first, second, and third configuration examples show that the shape of the FZPL formed on the Low-E film is the same as in the first embodiment, but the difference is that the substrate to which the Low-E film is coated is not the glass plate 10, but a substrate (base) 50 bonded to the glass plate.

[0089] <First configuration example of the second embodiment> Referring to Figures 10 and 11, in the second embodiment, the FZPL4 is positioned opposite the opening region 26 where the Low-E film 20C on the glass plate 10C has been removed.

[0090] The front view of the Low-E film 60 in FZPL4 according to the first configuration example of the second embodiment is the same as that of FZPL1, as shown in Figure 6(a).

[0091] Therefore, referring to Figure 11, in FZPL4, the shielding portion S is formed by a homogeneous pattern 61 in which the Low-E film 60 on the substrate 50 is formed uniformly without holes or gaps. On the other hand, the permeable portion T is formed by an exposed portion 62 in which the Low-E film is cut out and the indoor-side surface 51 of the substrate 50 is exposed.

[0092] In this configuration example, the FZPL4 is positioned on the glass plate 10C so as to face the opening region 26 where the Low-E film 20C has been removed. Therefore, without being affected by the radio wave blocking by the Low-E film 20C, the FZPL4 can focus radio waves of a first wavelength with its shielding portion S and transmitting portion T, and transmit radio waves of a second wavelength with its transmitting portion S, even indoors.

[0093] <Second configuration example of the second embodiment> Figure 12 is a cross-sectional view of the window glass 300A with FZPL in the second configuration example of the second embodiment. The front configuration of the Low-E film 60A in FZPL5 in the second configuration example of the second embodiment is the same as that of FZPL2 shown in Figure 7(a).

[0094] Therefore, referring to Figure 12, in the laminated FZPL5, the transparent portion T is formed by a Low-E film 60A processed into a lattice-like FSS structure. Figure 12 shows an example where the Low-E film of the FSS structure constituting the transparent portion T is a small grid portion 63 with a fine grid shape. More specifically, it is preferable that the circumference of the unit shape of the FSS structure of the transparent portion T is 1 / 100 to 1 times the first wavelength λ1 and 1 / 600 to 1 / 6 times the second wavelength λ2.

[0095] Furthermore, the shielding portion S is formed by a homogeneous pattern 61 on the substrate 50A, where the Low-E film 60A is uniformly formed without holes or gaps, similar to Figure 11.

[0096] In this configuration example, the FZPL5 is positioned opposite the opening region 26 where the Low-E film 20C on the glass plate 10C has been removed. Therefore, without being affected by the radio wave blocking effect of the Low-E film 20C, the shielding portion S and the transmitting portion T of the FZPL5 can focus radio waves of the first wavelength, and the transmitting portion T can transmit radio waves of the second wavelength indoors.

[0097] Furthermore, in this configuration example, the transmissive portion T of the FZPL5 is made with an FSS configuration to suppress the loss of heat shielding and aesthetics due to the Low-E film. The heat-shielding FZPL5 is then provided opposite the portion that has lost heat shielding due to the opening region 26 where the Low-E film 20C on the outdoor glass plate 10C has been removed. As a result, the Low-E film 20C and 60A are continuously present when viewed from the indoor side of the entire window glass 300A with FZPL, so the reduction in heat shielding can be suppressed without significantly impairing the aesthetics.

[0098] <Third Configuration Example of the Second Embodiment> Figure 13 is a cross-sectional view of the window glass 300B with FZPL in the third configuration example of the second embodiment. The front configuration of the Low-E film 60B in the FZPL6 according to the third configuration example of the second embodiment is the same as that of the FZPL3 shown in Figure 8(a).

[0099] Therefore, referring to Figure 13, in the laminated FZPL6, the shielding portion S is formed by a Low-E film 60B processed into an FSS structure, which has different characteristics from the transmitting portion. In this example, the FSS structure of the shielding portion S is formed by a grid created by vertical and horizontal slits, and is shown to be formed by a large grid portion 64, which has a larger repeating unit shape than the transmitting portion. More specifically, it is preferable that the perimeter of the unit shape of the FSS structure of the shielding portion S (sum of the four sides of the square) is 1 / 4 to 2 times the first wavelength λ1 and 1 / 25 to 1 / 4 times the second wavelength λ2.

[0100] Furthermore, the permeable portion T is formed by a small grid portion 63, which is a Low-E film processed into a lattice-like FSS structure, similar to the second configuration example.

[0101] In this configuration example, the FZPL6 is positioned on the glass plate 10C so as to face the opening region 26 where the Low-E film 20C has been removed, and the shielding portion S and the transmitting portion T of the FZPL6 are configured as FSS. Therefore, without being affected by the radio wave blocking by the Low-E film 20C, the shielding portion S and the transmitting portion T of the FZPL6 can focus radio waves of the first wavelength indoors, and the shielding portion S, whose blocking is suppressed by the transmitting portion T and the FSS configuration, can transmit radio waves of the second wavelength.

[0102] Furthermore, as shown in Figure 9 above, the second and third configurations exhibit good visibility from a distance and suppression of heat shielding reduction. Therefore, the mounting type FZPL of the second embodiment is particularly preferable to be FZPL5 and 6 of the second and third configurations.

[0103] (Modification 1 of the second embodiment) In the second embodiment described above, the region (aperture region) facing FZPL4(5,6) in the Low-E coated glass (10C+20C) was shown as an example where the Low-E film was completely cut out and no Low-E film was present. However, in Low-E glass, the region facing FZPL4(5,6) may be a transparent portion composed of small grid sections that transmit radio waves of the first and second frequencies.

[0104] Figure 14 is a cross-sectional view of a window glass with FZPL (laminated window glass) 3000 of a modified example 1 of the second embodiment. In this example, the region opposite to the FZPL 4(5, 6) is the aperture-transmitting region (second transmitting portion) 27 of the Low-E glass, and a Low-E film with the same configuration as the small grid portion 24 in Figure 7(a) exists on the outer surface 11D of the glass plate 10D.

[0105] Therefore, in this modified example, the Low-E film 20D that constitutes the aperture-transmitting region 27 on the glass plate 10D to which the FZPL4(5,6) is attached suppresses the reduction in visibility from a distance and heat shielding performance more effectively than when the area is cut out. As a result, in this modified example, the mounting type FZPL in the second embodiment may be any of the FZPL4, 5, or 6 from the first, second, or third configuration examples.

[0106] (Modification 2 of the second embodiment) In the second embodiment shown in Figures 10 to 13, an example was described in which a portion of the Low-E film is cut out from Low-E glass and an FZPL is attached. However, in particular, the FZPLs 5 and 6 in the second and third configurations have good visibility from a distance, so they may also be attached to plain glass that is not Low-E glass.

[0107] Furthermore, when FZPL5 and 6, which have the FZPL configurations of the second and third configuration examples, are mounted on plain glass that is not Low-E glass, the conductive film constituting the FZPL layer of FZPL5 and 6 does not have to be a Low-E film. In that case, it is desirable that the conductive films 60A and 60B constituting the FZPL in FZPL5 and 6 are formed of transparent conductive films such as zinc oxide (ZnO), tin oxide (SnO2), tin-doped indium oxide (ITO), indium oxide-tin oxide (IZO), or metal nitrides such as titanium nitride (TiN) or chromium nitride (CrN).

[0108] <<Experimental Example>> The inventors created an analytical model that mimicked an FZPL integrated window glass and compared various performance characteristics such as the gain and transmission coefficient of FZPL in each analytical model.

[0109] (Example 1: Comparison with a comparative example) Figure 15 shows an analysis model that simulates Comparative Example 1, Comparative Example 2, and the first configuration example in Example 1.

[0110] In comparative example 1, analysis model 1, a Low-E film 20X was coated on one side of the outer surface of the glass plate 10X, and no FZPL was provided.

[0111] In comparative example 2, analysis model 2, a Low-E film 20X was coated over the entire outer surface of the glass plate 10Y, and FZPL9 was formed on the inner surface with the Low-E film 20Y, which consisted of a homogeneous pattern 28 and exposed portions 29.

[0112] In the analysis model 3, which mimics configuration example 1, an FZPL1 was formed on the outer surface of the glass plate 10, consisting of a homogeneous pattern 22 made of a Low-E film 20 and exposed portions 23.

[0113] The various dimensions are as follows: Glass plate sizes 10X, 10Y, 10: 100mm x 100mm Glass plate 10X, 10Y, 10, thickness: 4 mm Surface resistance values ​​of Low-E films 20X, 20Y, and 20: R_s = 2.65 Ω / □ Design value for FZPL9 and FZPL1 in analysis models 2 and 3: 28 GHz Focal length of FZPL9 and FZPL1 in analysis models 2 and 3: 50 mm Number of zones for FZPL9 and FZPL1 in analysis models 2 and 3: 3 That's what I decided.

[0114] Figure 16 is a graph showing the simulated gains for analysis model 1, analysis model 2, and analysis model 3 in Figure 15.

[0115] As shown in Figure 16, in analysis model 1, where the entire surface is coated with a Low-E 20X film, radio waves do not pass through easily, and the overall gain is low at all distances. In analysis model 2, the gain is improved compared to analysis model 1 at the focal length of 50 mm, but it is still low at -30 dB.

[0116] In contrast, in analysis model 3, which mimics the first configuration example, the gain is approximately +10dB at a focal length of 50mm.

[0117] This graph shows that by processing the Low-E film to form an FZPL, as in analysis model 3 which mimics the first configuration example of the present invention, the effect of improving the gain reduced by the Low-E film is significantly higher than when an FZPL is provided in addition to the Low-E film, as in analysis model 2.

[0118] (Example 2: Gain for each configuration example at the first wavelength (set wavelength)) Figure 17 is a table showing the various characteristics of analysis models 4, 5, and 6, which are modeled after the first, second, and third configuration examples in Example 2.

[0119] In Figure 17, analysis model 4 is an FZPL modeled after the first configuration example, analysis model 5 is an FZPL modeled after the second configuration example, and analysis model 6 is an FZPL modeled after the third configuration example.

[0120] The various dimensions of analysis models 4, 5, and 6 are as follows: Glass plate size: 300mm x 300mm Glass plate thickness: 0.55mm Surface resistance of Low-E film: R_s = 2.65 Ω / □ FZPL design wavelength: 28 GHz The focal length of the FZPL lens was set to 300 mm.

[0121] In this example, the unit cell of the small grid portion constituting the transparent part of the second and third configuration examples is set to have a side length of 1 / 50 wavelength and a circumference of 1 / 12.5 wavelength with respect to the first wavelength λ1 of 28 GHz.

[0122] Furthermore, in the third configuration example, the unit cell of the large grid section constituting the shielding section is set to have a side length of 1 / 5 wavelength and a circumference of 4 / 5 wavelength with respect to the first wavelength λ1 of 28 GHz, and to have a side length of 1 / 45 wavelength and a circumference of 4 / 45 wavelength with respect to the second wavelength λ2 of 3.3 GHz.

[0123] Figure 18 is a graph showing the gain near the focal point when simulating with analysis models 4, 5, and 6 in Figure 17, using 28 GHz as the set wavelength.

[0124] As shown in Figure 18, at the first wavelength λ1 (28 GHz), which is the target wavelength for focusing radio waves with FZPL, the gain is 10 dB or more at the focal length of 300 mm in all analysis models. Therefore, it can be said that all configurations effectively focus radio waves as FZPL.

[0125] (Example 3: Transmission characteristics of Low-E film on glass for each state (for each slit spacing)) Next, without constructing an FZPL on a glass plate, we simulated the transmission characteristics by changing the state of the Low-E film.

[0126] Figure 19 shows the analysis models 7, 8, 9, and 10 in Example 3, with varying states of the Low-E film. The various dimensions of the analysis models 7-10 in this study are as follows: Glass plate size: 300mm x 300mm Glass plate thickness: 0.55mm Surface resistance of Low-E film: R_s = 2.65Ω / □ That is the case.

[0127] In this example's analysis model, as shown in Figure 19, the FZPL is not formed with a Low-E film, and each state is uniformly applied to the entire surface of one side of the glass plate.

[0128] More specifically, in analysis model 7, a homogeneous Low-E film is coated over the entire surface of the glass plate. In analysis model 8, a small grid-like Low-E film with a slit pitch of 0.2 mm is coated over the entire surface of the glass plate. In analysis model 9, a large grid-like Low-E film with a slit pitch of 2 mm is coated over the entire surface of the glass plate. In analysis model 10, the glass plate is plain glass without a Low-E film coating.

[0129] Figure 20 is a graph showing the transmission characteristics simulated for analysis models 7-10 in Figure 19.

[0130] Generally, a transmission characteristic of -10dB or higher indicates that it transmits radio waves in that frequency band. In the analysis model 7 for a fully homogeneous Low-E film, the transmission coefficient S is... 21 However, there is no region where the level is above -10dB, indicating that radio waves are not being transmitted.

[0131] On the other hand, in analysis model 10, which is entirely made of plain glass, the transmission coefficient S is calculated across the entire range from 0 GHz to 40 GHz. 21 However, it is above -10dB, meaning it is allowing radio waves to pass through.

[0132] Furthermore, analysis model 8, which is coated with a Low-E film in a small grid pattern with a full slit pitch of 0.2 mm, shows a transmission coefficient S across the entire range from 0 GHz to 40 GHz. 21However, it is above -10dB, indicating that radio waves are being transmitted. In particular, the transmission coefficient S is high for both the first wavelength λ1, which is 26-29GHz, where we want to focus the radio waves, and the second wavelength λ2, which is 0-6GHz, which is the Sub-6 band, where we want to transmit radio waves. 21 However, the level must be above -10dB, and furthermore, between -5dB and 0dB.

[0133] Therefore, a Low-E film with a slit pitch of 0.2 mm and a small grid pattern can be said to function as a FSS (Fixed Stencil) that transmits radio waves for the first and second wavelengths.

[0134] On the other hand, analysis model 8, which is coated with a large grid-like Low-E film with a slit pitch of 2 mm across the entire surface, shows a transmission coefficient S in the range of 0 GHz to 40 GHz. 21 This gradually decreases. Therefore, in the Sub-6 band, which corresponds to the second wavelength λ2 of 0-6 GHz and where we want to transmit waves, the transmission coefficient is greater than -10 dB, and radio waves between -5 dB and 0 dB are transmitted. Also, in the first wavelength λ1 of 26-29 GHz and where we want to focus radio waves, the transmission coefficient becomes less than -10 dB.

[0135] Therefore, a Low-E film with a large grid pattern and a slit pitch of 2 mm can be said to function as an FSS (Fixed Scaling System) that does not transmit radio waves at the first wavelength but transmits radio waves at the second wavelength.

[0136] (Example 4: Transmission characteristics at the first and second wavelengths) Figure 21 is a table showing the various characteristics of analysis models 11 and 6, which are modeled after the first and third configuration examples in Example 4.

[0137] In Figure 21, analysis model 11 is FZPL1, which mimics the first configuration example, and analysis model 6 is FZPL3, which mimics the third configuration example.

[0138] Unlike analysis model 4, analysis model 11 has a shielding section formed of a copper film.

[0139] Figure 22 is a graph showing the transmission characteristics simulated for analysis models 6 and 11 in Figure 21.

[0140] As shown in Figure 22, at 28 GHz in the millimeter-wave band, which is the design wavelength of the FZPL, the transmission coefficient S is found in both analysis models 6 and 11 at a focal length of approximately 300 mm. 21 Because it is above +10dB, it is focusing the radio waves.

[0141] On the other hand, in the Sub6 band at 3.3 GHz, at a focal length of around 300 mm, in analysis model 6 which mimics configuration example 3, the transmission coefficient S 21 It is approximately -1 dB, and in the analysis model 11 which mimics configuration example 1, the transmission coefficient S 21 This is approximately -5dB.

[0142] More specifically, at a focal length of around 300mm, the FZPL1 in analysis model 11 exhibits a slight decrease in the transmission characteristics of Sub-6 band radio waves, such as 3.3GHz. As shown in Figure 20 above, Sub-6 band radio waves pass through the transparent portion of the plain glass that constitutes the FZPL1, but do not pass through the shielding portion composed of a homogeneous Low-E film.

[0143] On the other hand, in analysis model 6's FZPL3, both the transmission and shielding sections are treated with FSS processing, resulting in minimal degradation of the transmission characteristics of Sub-6 band radio waves. As shown in Figure 20 above, Sub-6 band radio waves pass through the transmission section of the small grid and also through the shielding section of the large grid that constitutes FZPL3.

[0144] In this simulation, analysis model 6 showed an example where the transmission coefficient at 3.3 GHz was -1 dB. However, it is also possible to improve the transmission loss of the glass by acting as a matching layer, in which case FZPL3 can transmit radio waves of the second wavelength with a positive value. Therefore, FZPL3 in the third configuration example can transmit the second wavelength by -5 dB or more to 3 dB.

[0145] (Example 5: Performance summary for each comparative example and configuration example) Figure 23 is a table summarizing the film retention rate, solar heat gain coefficient, and performance of the first, second, and third configurations of Example 5, as well as Comparative Example 1.

[0146] Here, the solar heat gain coefficient is an indicator of heat shielding performance, showing the proportion of solar radiation that enters the room through the glass. For heat shielding and reduction of cooling load, glass with a low solar heat gain coefficient is effective. Also, there are two types of Low-E films: two layers of silver and three layers of silver. The three-layer silver film has higher heat shielding performance, i.e., a lower solar heat gain coefficient. For each film, an FZPL (Fiber Temperature Plan) was created and various performance parameters were measured.

[0147] Figure 24 is a graph showing the solar heat gain coefficient for two Low-E film layers and three Low-E film layers as shown in Figure 23. For each layer in Figure 24, the points represent measured points, and the lines are approximate lines connecting these measured points.

[0148] As shown in the table in Figure 23 and the graph in Figure 24, plain glass has the highest solar heat gain coefficient, while the completely homogeneous Low-E (uncoated) state, as shown in the comparative example, has the lowest solar heat gain coefficient.

[0149] Furthermore, in the first configuration example, since the Low-E film is not present in the transparent area, the only remaining part of the film is the shielding area, and as shown in Figure 23, the film retention rate is 0.5 (=50%).

[0150] In that case, as shown in Figure 24, the effect of the Low-E film on reducing the solar heat gain coefficient compared to plain glass is also reduced to 50% compared to uniformly Low-E film.

[0151] Therefore, in order to suppress the decrease in heat shielding performance, which is the solar heat gain coefficient, due to the Low-E film, the film residue rate is preferably 70% to 99%, and for this purpose, the FZPL is preferably the second and third configuration examples.

[0152] Although an exemplary embodiment of the Fresnel zone plate lens of the present invention has been described above, the present invention is not limited to the specifically disclosed embodiments, and various modifications and changes are possible without departing from the scope of the claims.

[0153] This international application claims priority based on Japanese Patent Application No. 2022-018309, filed on 8 February 2022, and the entire contents of No. 2022-018309 are incorporated herein by reference. [Explanation of Symbols]

[0154] 1,2,3 Fresnel Zone Plate Lens (FZPL) 4,5,6 Fresnel zone plate lenses (FZPL, laminated) 10, 10A, 10B Glass plate (base) 10C, 10D glass plate 11 Outer surface 20,20A,20B,20C,20D Low-E film (conductive film) 21 Extra-regional Low-E membrane 22. Homogeneous remaining area (homogeneous pattern) 23 Exposed part 24 Small grid section 25 Large grid section 26 Opening area 27. Aperture-transmitting region (second transmissive area) 30, 30A, 30B FZPL integrated window glass (window glass) 50,50A,50B base 60,60A,60B,60C Low-E film (conductive film) 61. Homogeneous pattern (conductor part) 62 Exposed part 63 Small grid section 64 Large grid section 80 Wall 90 Smartphones 300, 300A, 300B FZPL-coated window glass (window glass, laminated window glass) 3000 FZPL-coated window glass (window glass, laminated window glass)

Claims

1. Substrate and, A conductive film formed on the substrate, which transmits radio waves, It has a conductive film formed on the substrate and a shielding portion which has a lower degree of radio wave transmission than the transparent portion, A Fresnel zone plate lens (FZPL) that focuses radio waves of a first wavelength λ1 at a focal point by having the transmitting portion and the shielding portion arranged alternately in concentric circles, The aforementioned transmission portion is an FSS (Frequency Selective Plate) structure that transmits the first wavelength λ1 radio waves. Fresnel zone plate lens.

2. The FSS structure of the aforementioned transmission section transmits radio waves of the first wavelength λ1 by -5 dB or more. The Fresnel zone plate lens according to claim 1.

3. The shielding section of the FZPL has an FSS structure. The Fresnel zone plate lens according to claim 1.

4. The FSS structure of the shielding portion prevents the transmission of radio waves of the first wavelength λ1 by -10 dB or more. The Fresnel zone plate lens according to claim 3.

5. The FSS structure of the transmission portion and the FSS structure of the shielding portion transmit radio waves of a second wavelength λ2, which is different from the first wavelength λ1, to a level of -5 dB or more and 0 dB or less. The Fresnel zone plate lens according to claim 3.

6. The Fresnel zone plate lens transmits radio waves of the second wavelength by -5 dB or more to 3 dB. The Fresnel zone plate lens according to claim 5.

7. The FSS structure of the transparent portion is a grid structure with two-directional slits, and the perimeter of the unit shape is 1 / 100 to 1 times the first wavelength λ1 and 1 / 600 to 1 / 6 times the second wavelength λ2. The Fresnel zone plate lens according to claim 5.

8. The FSS structure of the shielding portion is a grid structure with two-way slits, and the perimeter of the unit shape is 1 / 4 to 2 times the first wavelength λ1 and 1 / 25 to 1 / 4 times the second wavelength λ2. The Fresnel zone plate lens according to claim 5.

9. The first wavelength λ1 is 6 GHz to 100 GHz, The second wavelength λ2 is 400 MHz to 6 GHz. The Fresnel zone plate lens according to claim 5.

10. The FSS structure described above has a slit in only one direction, aligned with the polarization direction. The Fresnel zone plate lens according to claim 1.

11. The FSS structure has a film rate of 70% to 99% for the conductive film. The Fresnel zone plate lens according to claim 1.

12. The Fresnel rings of the FZPL are formed in order 4 or higher. The Fresnel zone plate lens according to claim 1.

13. The conductive film is a Low-E film. The Fresnel zone plate lens according to claim 1.

14. The substrate is glass or resin. The Fresnel zone plate lens according to claim 1.

15. The substrate is a window glass on which a conductive film is formed, The Fresnel zone plate lens according to any one of claims 1 to 13 is formed on the same plane as the conductive film outside the Fresnel zone plate lens area. Window glass with integrated Fresnel zone plate lens.

16. A Fresnel zone plate lens according to any one of claims 1 to 14, It comprises a glass plate on which a conductive film is formed, The Fresnel zone plate lens is attached to the glass plate, In the region of the glass plate facing the Fresnel zone plate lens, the conductive film has an FSS (Frequency Selective Plate) structure that transmits the first wavelength λ1 radio waves. Window glass with Fresnel zone plate lens.

17. A Fresnel zone plate lens according to any one of claims 1 to 14, The glass plate on which the conductive film is formed comprises The Fresnel zone plate lens is attached to the glass plate, At least a portion of the region of the glass plate facing the Fresnel zone plate lens is free from the conductive film. Window glass with Fresnel zone plate lens.

Images