Frequency selective surface loading member and vehicle window member

Abstract

To provide a frequency selective surface loading member capable of reducing distortion of a wave surface generated in a boundary of a region where a frequency selective surface is provided and a region where the frequency selective surface is not provided.SOLUTION: In a frequency selective surface loading member, a frequency selective surface that transmits an electromagnetic wave of a frequency F on a dielectric body is provided. The frequency selective surface includes: a conductive part; and a non-conductive part, and a plurality of conductive parts is two-dimensionally arranged. In a plan view of the frequency selective surface, when a first region having the frequency selective surface, and a second region where the frequency selective surface is not provided are defined, the frequency selective surface is constructed by a pattern that a penetration phase of the electromagnetic wave of the frequency F is changed as approaching the penetration phase of the electromagnetic wave of the frequency F to a second region in at least first direction of a second direction crossed to the first direction so as to be approached to the penetration phase of the electromagnetic wave of the frequency F in the second region.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a frequency selective surface loading member and a window member for a vehicle. [Background technology]

[0002] In recent years, with the increase in communication speed and communication capacity, the frequency band of radio waves used for communication has expanded to higher frequency bands. For example, recent fourth-generation mobile communication systems (hereinafter referred to as "4G") and fifth-generation mobile communication systems (hereinafter referred to as "5G") use radio waves in frequency bands of several hundred MHz to several tens of GHz.

[0003] To perform communication in such high frequency bands, it has been proposed to install a radar device in an emblem or front grille on the exterior of a vehicle. In recent years, however, it has also been considered to install a radar device inside the vehicle, particularly on the passenger compartment side of the windshield, so that communication can be performed efficiently from a position relatively higher above the ground than in an emblem or front grille.

[0004] However, laminated glass used in windshields has the problem of reduced radio wave transmittance due to reflection and absorption of radio waves as they pass through. Furthermore, radio wave transmittance varies depending on the angle of the windshield and the thickness of the glass. Furthermore, windshields are often fitted with heat-reflecting films to reduce air conditioning loads, but in these cases, there is also the problem of radio wave shielding caused by the conductive film contained in the heat-reflecting film.

[0005] The above problem can occur not only in laminated glass for vehicles, but also in Low-E double glazing used in windows for buildings, etc., and with the use of high-frequency bands in communications, there is a demand for improving radio wave transmittance while maintaining good thermal performance.

[0006] To address the above problem, for example, Patent Document 1 discloses a method for detecting objects using an on-board radar that can detect objects by suppressing reflections from a windshield, even when radar waves are transmitted and received through a windshield equipped with a frequency selective surface (FSS) that selectively passes radar waves in a preset frequency band.

[0007] Furthermore, Patent Document 2 discloses a frequency selective surface for a vehicle that can effectively reduce the reflection coefficient for radar waves in a desired frequency band even if the angle of incidence of the radar waves on the frequency selective surface (FSS) installed on a dielectric member such as a bumper cover varies depending on the position on the frequency selective surface. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2018-179706 [Patent Document 2] Japanese Patent Application Publication No. 2018-019136 Summary of the Invention [Problem to be solved by the invention]

[0009] However, when transmitting and receiving radar waves through a windshield, if a frequency selective surface (FSS) as disclosed in Patent Documents 1 and 2 is installed, distortion of the wavefront occurs at the boundary between the area where the frequency selective surface is provided and the area where it is not provided. For this reason, a windshield equipped with a frequency selective surface (hereinafter referred to as "frequency selective surface (FSS)") has the problem that the detection performance of radar that penetrates near the boundary between these areas is degraded due to this distortion.

[0010] The present invention provides a frequency selective surface loading member and a vehicle window member that can reduce distortion of a wavefront that occurs at the boundary between an area where a frequency selective surface is provided and an area where no frequency selective surface is provided. [Means for solving the problem]

[0011] The frequency selective surface loading member of the present invention comprises a dielectric and a frequency selective surface on the dielectric that transmits radio waves of frequency F, the frequency selective surface having a plurality of cells that are unit areas including conductive portions and non-conductive portions, the plurality of cells being arranged two-dimensionally without gaps, and when a first area having the frequency selective surface and a second area not having the frequency selective surface are defined in a planar view of the dielectric, the frequency selective surface has a pattern in which the transmission phase of the radio waves of frequency F changes to approach the transmission phase of the radio waves of frequency F in the second area as it approaches the second area, at least in the first direction among a first direction and a second direction intersecting the first direction.

[0012] Furthermore, in a frequency selective surface loading member according to one embodiment of the present invention, the frequency selective surface may be configured such that the cells are composed of non-conductive portions that surround the entire circumference of one of the conductive portions, the non-conductive portions extend in the first direction and the second direction to form a lattice pattern, and the width of the conductive portion in the first direction may gradually decrease as it approaches the second region.

[0013] In the frequency selective surface loading member according to an aspect of the present invention, the cells of the frequency selective surface extending in the first direction may have the same width.

[0014] In the frequency selective surface loading member according to one aspect of the present invention, the width of the cells extending in the first direction of the frequency selective surface may gradually decrease toward the second region.

[0015] In the frequency selective surface loading member according to one aspect of the present invention, the width of the cells extending in the second direction of the frequency selective surface may gradually decrease toward the second region.

[0016] In the frequency selective surface loading member according to an aspect of the present invention, the frequency selective surface may have the same width of the cells extending in the second direction.

[0017] In the frequency selective surface loading member according to an aspect of the present invention, the width of the conductive portion extending in the second direction of the frequency selective surface may be uniform.

[0018] In the frequency selective surface loading member according to one aspect of the present invention, the width of the conductive portion extending in the second direction of the frequency selective surface may gradually decrease toward the second region.

[0019] In addition, in the frequency selective surface loading member according to one aspect of the present invention, the plurality of cells may have the same width in the first direction of the non-conductive portion in a closed loop shape surrounding the entire periphery of the conductive portion.

[0020] In the frequency selective surface loading member according to an aspect of the present invention, the non-conductive portions of the plurality of cells may have the same width in the second direction in the closed loop shape.

[0021] In the frequency selective surface loading member according to an aspect of the present invention, the closed loop shape may be a rectangular loop shape.

[0022] In addition, in a frequency selective surface loading member according to one embodiment of the present invention, the frequency selective surface may have a plurality of cells each having a non-conductive portion in a closed loop shape inside the outer edge of the cell, and the conductive portion may have a first conductive portion arranged outside the closed loop shape and a second conductive portion arranged inside the closed loop shape, and be arranged two-dimensionally without gaps, and the width of the second conductive portion in the first direction may gradually decrease as it approaches the second region.

[0023] In the frequency selective surface loading member according to an aspect of the present invention, the cells of the frequency selective surface extending in the first direction may have the same width.

[0024] In the frequency selective surface loading member according to one aspect of the present invention, the width of the cells extending in the first direction of the frequency selective surface may gradually decrease toward the second region.

[0025] In the frequency selective surface loading member according to one aspect of the present invention, the width of the cells extending in the second direction of the frequency selective surface may gradually decrease toward the second region.

[0026] In the frequency selective surface loading member according to an aspect of the present invention, the frequency selective surface may have the same width of the cells extending in the second direction.

[0027] In the frequency selective surface loading member according to one aspect of the present invention, the width of the second conductive portion in the second direction may be gradually reduced toward the second region.

[0028] In the frequency selective surface loading member according to an aspect of the present invention, the frequency selective surface may have the same width as the second conductive portion extending in the second direction.

[0029] In the frequency selective surface loading member according to an aspect of the present invention, the width of the second conductive portion extending in the second direction may gradually decrease toward the second region.

[0030] In the frequency selective surface loading member according to an aspect of the present invention, the closed loop shape may be a rectangular loop shape.

[0031] In addition, in a frequency selective surface loading member according to one embodiment of the present invention, the frequency selective surface may have a plurality of cells each having a non-conductive portion in the shape of a circular or elliptical closed loop inside the outer edge of the cell, the conductive portion having a first conductive portion arranged outside the closed loop shape and a second conductive portion arranged inside the closed loop shape, and arranged two-dimensionally without gaps, and the width of the second conductive portion in the first direction may gradually decrease as it approaches the second region.

[0032] In the frequency selective surface loading member according to an aspect of the present invention, the second conductive portions of the frequency selective surface may have the same width in the second direction.

[0033] In the frequency selective surface loading member according to one aspect of the present invention, the width of the second conductive portion in the second direction may be gradually reduced toward the second region.

[0034] Furthermore, the frequency selective surface loading member according to one aspect of the present invention may be point symmetric with respect to the center of gravity.

[0035] In addition, in a frequency selective surface loading member according to one embodiment of the present invention, the dielectric may include a first glass substrate, a second glass substrate, and one or more intermediate films sandwiched between the first glass substrate and the second glass substrate.

[0036] Furthermore, in a frequency selective surface loaded member according to one aspect of the present invention, the intermediate film may have a first intermediate film and a second intermediate film, and the frequency selective surface may be arranged between the first intermediate film and the second intermediate film.

[0037] In the frequency selective surface loading member according to an aspect of the present invention, the dielectric may be a laminated glass for a vehicle.

[0038] In the frequency selective surface loading member according to an aspect of the present invention, the frequency F may be in the range of 1 GHz to 100 GHz.

[0039] Furthermore, the frequency selective surface loading member according to one aspect of the present invention may be a window member for a vehicle.

[0040] Furthermore, the frequency selective surface loading member according to an aspect of the present invention may be a windshield for a vehicle. [Effects of the Invention]

[0041] The frequency selective surface loading member according to the present invention can reduce distortion of the wavefront of the radar wave that is transmitted at the boundary between an area where the frequency selective surface is provided and an area where the frequency selective surface is not provided. [Brief explanation of the drawings]

[0042] [Figure 1] FIG. 1(a) shows a plan view of an example of an FSS loading member according to the present invention, and FIG. 1(b) shows an example of a dielectric substrate (laminate) that is one component of the FSS loading member. [Figure 2] FIG. 2 shows a plan view of an FSS according to one embodiment of the present invention. [Figure 3] FIG. 3 shows a plan view of an FSS according to another embodiment of the present invention. [Figure 4] FIG. 4 shows a plan view of an FSS according to another embodiment of the present invention. [Figure 5] FIG. 5 shows a plan view of an FSS according to another embodiment of the present invention. [Figure 6] FIG. 6 shows a plan view of an FSS according to another embodiment of the present invention. [Figure 7] FIG. 7 shows a plan view of an FSS according to another embodiment of the present invention. [Figure 8] FIG. 8 shows a cross-sectional view of the FSS loading member in the first embodiment. [Figure 9] FIG. 9 shows the unit patterns of FSS in Example 1 and Comparative Example 1. [Figure 10] FIG. 10 shows the arrangement of unit patterns of the FSS in the first embodiment. [Figure 11] FIG. 11 shows the arrangement of unit patterns of FSS in Comparative Example 1. [Figure 12] FIG. 12(a) shows the transmission characteristics of the FSS loading member in Example 1, and FIG. 12(b) shows the phase difference of the electric field after passing through the FSS loading member in Example 1. [Figure 13] 13(a) shows the phase characteristics after passing through the FSS loading member in Example 1 and Comparative Example 1, and FIG. 13(b) shows the effective values ​​of the electric field after passing through the FSS loading member in Example 1 and Comparative Example 1. [Figure 14] FIG. 14 shows the electric field distribution when a plane wave is incident on the FSS loading member of Example 1. [Figure 15] FIG. 15 shows the electric field distribution when a plane wave is incident on the FSS loading member of Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0043] Hereinafter, embodiments of the present invention will be described in detail. In addition, in the following drawings, components and parts that perform the same function may be described with the same reference numerals, and duplicated descriptions may be omitted or simplified. Furthermore, the embodiments shown in the drawings are schematic in order to clearly explain the present invention, and do not necessarily accurately represent the size or scale of an actual product.

[0044] (First embodiment) 1A is a plan view showing a frequency selective surface loading member 101 according to the first embodiment, which has a first region 10 and a second region 20 around the first region 10. As shown in FIG. 1A, the first region 10 is a region that has a frequency selective surface (FSS) in a plan view of the frequency selective surface loading member 101, and the second region 20 is a region that does not have a frequency selective surface (FSS). In other words, the frequency selective surface loading member 101 is defined, in a plan view of the dielectric, as having a first region 10 that has an FSS and a second region that does not have an FSS.

[0045] The frequency selective surface loading member 101 (hereinafter also referred to as the FSS loading member 101) according to this embodiment has a dielectric in a first region 10 and a frequency selective surface (hereinafter also referred to as the FSS) on the dielectric that transmits radio waves of frequency F. As will be described later, the FSS has conductive portions 11 and non-conductive portions 12 and is arranged two-dimensionally in the XY plane of FIG. 1(a). In this case, the FSS loading member 101 forms an FSS pattern in which the transmission phase of the FSS for radio waves of a predetermined frequency F approaches the transmission phase in the second region 20 as it approaches from the first region 10 to the second region 20. Note that in this specification, the range of radio waves of frequency F is described as 1 GHz to 100 GHz, including quasi-millimeter waves and millimeter waves, but the range may be 10 GHz to 100 GHz or 30 GHz to 100 GHz.

[0046] The FSS loading member 101 according to this embodiment is composed of a single dielectric substrate, and the FSS may be disposed on the main surface of the single substrate. Furthermore, the FSS loading member 101 according to this embodiment is composed of a laminate in which multiple dielectrics are stacked, and the FSS may be disposed on any surface of the laminate. The FSS loading member 101 mainly comprises a dielectric (substrate) and an FSS, and each component of the FSS loading member 101 will be described below.

[0047] <Dielectric (substrate)> Fig. 1(b) is a perspective view showing a dielectric substrate 50 made of a laminate, one of the components of the FSS loading member 101. The dielectric substrate 50 shown in Fig. 1(b) has a first substrate 51, a second substrate 52, and an intermediate film 53 sandwiched between the first substrate 51 and the second substrate 52. Fig. 1(b) shows an example in which the intermediate film 53 is formed by laminating a first intermediate film 53A and a second intermediate film 53B in this order from the first substrate 51 side, but the intermediate film 53 may be one layer or three or more layers.

[0048] The first substrate 51 and the second substrate 52 can be, for example, a glass substrate or a resin substrate, and the intermediate film 53 can be, for example, a resin film. The intermediate film 53 (first intermediate film 53A, second intermediate film 53B) can be, for example, a thermoplastic resin such as polyvinyl butyral (PVB), ethylene vinyl acetate copolymer (EVA), or cycloolefin polymer (COP) having a thickness of about 0.3 mm to 1.0 mm.

[0049] When the first substrate 51 and the second substrate 52 are glass substrates, they may be made of glass having the same composition or different compositions. Furthermore, the first substrate 51 (glass substrate 51) and the second substrate 52 (glass substrate 52) may have the same thickness or different thicknesses. When the first substrate 51 and the second substrate 52 have the same thickness, the thickness of each substrate can be, for example, about 2.0 mm. The type of glass substrate is not particularly limited, and examples include aluminosilicate glass, soda-lime glass, borosilicate glass, lead glass, alkali barium glass, and aluminoborosilicate glass. In particular, when the first substrate 51 and the second substrate 52 are glass substrates, the dielectric substrate 50 can be, for example, laminated glass for vehicles. Hereinafter, unless otherwise specified, the dielectric substrate 50 will be described as laminated glass.

[0050] Furthermore, the smaller the dielectric loss tangent (tan δ) at millimeter waves of the first substrate 51 and the second substrate 52, the more likely it is that the transmittance at millimeter waves will improve. When the first substrate 51 and the second substrate 52 are glass substrates, the tan δ at millimeter waves is preferably 0.05 or less. Even if the dielectric substrate 50 is a single glass plate, the tan δ at millimeter waves is preferably 0.05 or less.

[0051] As shown in (b) of FIG. 1, for the dielectric substrate 50, the main surface of the first substrate 51 (glass substrate 51) on the side opposite to the intermediate film 53 side is defined as the first surface 61, and the main surface on the intermediate film 53 side is defined as the second surface 62. Also, for the second substrate 52 (glass substrate 52), the main surface on the intermediate film 53 side is defined as the third surface 63, and the main surface on the side opposite to the intermediate film 53 side is defined as the fourth surface 64. Further, when the intermediate film 53 has a first intermediate film 53A and a second intermediate film 53B, the main surfaces facing each other are defined as the fifth surface 65. Here, the FSS constituting the first region 10 may be arranged on at least one of the first surface 61, the second surface 62, the third surface 63, the fourth surface 64, and the fifth surface 65.

[0052] Also, the dielectric substrate 50 shown in (b) of FIG. 1 is a laminated glass for a vehicle, and the first surface 61 is the main surface on the outside of the vehicle compartment, and the fourth surface 64 is the main surface on the inside of the vehicle compartment. In this case, from the viewpoint of weather resistance, it is preferable that the FSS constituting the first region 10 is arranged on at least one of the main surfaces of the second surface 62, the third surface 63, the fourth surface 64, and the fifth surface 65.

[0053] <FSS (First Region)> FIG. 2 is a plan view showing an example of the FSS 15 arranged in the first region 10 of the FSS loading member 101 according to the present embodiment. The FSS 15 is formed in a lattice shape by the conductive portion 11 and the non-conductive portion 12, and the (virtual) region surrounded by the broken line of the first region 10 shown in FIG. 2 is arranged two-dimensionally without gaps as a rectangular cell 16 that is the minimum unit region having the same shape. In particular, the FSS 15 is formed in a lattice shape with the non-conductive portion 12 extending in the first direction and the second direction. Each cell 16 of the FSS 15 shown in FIG. 2 has its region constituted by one conductive portion 11 and a non-conductive portion 12 surrounding the entire circumference of the one conductive portion 11, and in a plan view of the cell 16, the conductive portion 11 is formed in a rectangular patch shape. The FSS 15 illustrated in FIG. 2 has seven cells 16 arranged side by side in the first direction (X-axis direction) and seven cells 16 arranged side by side in the second direction (Y-axis direction) orthogonal to the first direction, and the first region 10 is constituted by 49 cells 16. Also, as shown in FIG. 2, the non-conductive portion 12 of each cell 16 in a plan view is in a closed loop shape, particularly a rectangular loop shape.

[0054] The conductive portion 11 is a portion having a sheet resistance of 50 Ω / □ or less at 20° C., and the non-conductive portion 12 is a portion having a sheet resistance of more than 50 Ω / □ at 20° C. In addition, in FSS15, the difference in sheet resistance at 20° C. between the conductive portion 11 and the non-conductive portion 12 may be 50 Ω / □ or more, preferably 100 Ω / □ or more, and more preferably 1000 Ω / □ or more.

[0055] The material constituting the conductive portion 11 of the FSS 15 is not particularly limited, but examples include materials containing metals such as Ag, indium tin oxide (ITO), Cu, Al, tin oxide doped with at least one of fluorine and antimony (SnO2:F,Sb), titanium nitride, niobium nitride, chromium nitride, zirconium nitride, and hafnium nitride. Among these, it is preferable to use at least one selected from the group consisting of Ag, ITO, tin oxide doped with at least one of fluorine and antimony (SnO2:F,Sb), and Cu. The FSS 15 may be formed by coating a conductive film on the main surface of a dielectric substrate and then etching it to form a pattern of the conductive portion 11. The dielectric substrate on which the FSS 15 is formed may be formed directly on the glass substrate 51 or 52, or may be a (transparent) resin film such as PET (polyethylene terephthalate) as a base material. In addition, when the FSS loading member 101 has a base material (film) such as PET for forming the FSS 15, which is different from the dielectric substrates such as the glass substrates 51 and 52, the base material is also treated as the FSS 15.

[0056] Furthermore, to improve visibility, the material of the conductive part 11 of the FSS 15 may be selected so that the visible light transmittance defined by ISO 9050:2003 is 60% or more. In this case, the visible light transmittance of the FSS 15 defined by the standard is preferably 65% ​​or more, and more preferably 70% or more. A transparent conductive film such as Ag or ITO may be used as the material of the conductive part 11 of the FSS 15, which can achieve the above-mentioned visible light transmittance.

[0057] In FIG. 2 , when the center of gravity of the first region 10 is 'G' in a planar view, the width of the conductive portion 11 in the first direction (X-axis direction) and the width of the conductive portion 11 in the second direction (Y-axis direction) gradually decrease as the first region 10 approaches the second region 20 along the first direction, using the cell 16 including the center of gravity G as a reference. Similarly, the width of the conductive portion 11 in the first direction and the width of the conductive portion 11 in the second direction gradually decrease as the first region 10 approaches the second region 20 along the second direction, using the cell 16 including the center of gravity G as a reference. However, the width (of the outer edge) of the non-conductive portion 12, i.e., the width of the cell 16 in the first direction is constant, and the width of the cell 16 in the second direction is constant. Note that if the FSS 15 is point-symmetric with respect to the center of gravity G, the transmission phase of the FSS for radio waves of a predetermined frequency F will have a distribution with a small bias as the FSS approaches the second region 20 from the first region 10.

[0058] As shown in Fig. 2, the FSS 15 constituting the first region 10 has non-conductive portions 12 formed in a lattice pattern overall in a plan view. When the FSS 15 is configured such that the widths of the conductive portions 11 in the first direction and the second direction gradually decrease as the FSS 15 approaches the second region 20 along the first direction, based on the center of gravity G, the transmission phases of the first-direction polarized waves and the second-direction polarized waves of the incident radio waves at a predetermined frequency F approach the transmission phase of the second region. Therefore, the FSS loading member 101 according to this embodiment suppresses discontinuity in the transmission phase at the boundary between the first region 10 and the second region 20 in the first direction for the first-direction polarized waves and the second-direction polarized waves of the incident radio waves at the predetermined frequency F. This alleviates changes in the intensity distribution of the radio waves transmitted through the FSS loading member 101, thereby suppressing distortion of the phase distribution.

[0059] Also, in Figure 2, the FSS 15 that constitutes the first region 10 gradually decreases in width in the first direction (X-axis direction) and in the second direction (Y-axis direction) of the conductive portion 11 as it approaches the second region 20 along the second direction, based on the cell 16 that includes the center of gravity G.

[0060] In this way, when the FSS 15 is configured so that the width in the first direction and the width in the second direction gradually decrease as it approaches the second region 20 along the second direction, based on the cell 16 including the center of gravity G, the transmission phase of the first-direction polarized wave and the second-direction polarized wave, among the radio waves incident at a predetermined frequency F, approaches the transmission phase of the second region. Therefore, the FSS loading member 101 according to this embodiment suppresses discontinuity in the transmission phase at the boundary between the first region 10 and the second region 20 in the second direction for the first-direction polarized wave and the second-direction polarized wave, among the radio waves incident at a predetermined frequency F, and thus the change in the intensity distribution of the radio waves transmitted through the FSS loading member 101 is alleviated, and distortion of the phase distribution is suppressed.

[0061] In the present embodiment, the FSS 15 corresponding to the first region 10 of the FSS loading member 101 has rectangular outer edges and is arranged without gaps in a two-dimensional matrix of 7 × 7 cells. However, this is not limiting. For example, the number of cells 16 aligned in the first direction may be different from the number of cells 16 aligned in the second direction. Furthermore, the FSS 15 only needs to have the widths of the conductive portions 11 in the first and second directions gradually decrease from the cell 16 including the center of gravity G or the cell 16 closest to the center of gravity G toward the second region 20. However, the FSS 15 may partially include a combination of two adjacent cells 16 in which at least one of the widths in the first direction and the widths in the second direction are the same. This may also be the case in the following embodiments. In this case, the FSS 15 has a configuration in which at least one of the widths in the first direction and the widths in the second direction gradually decrease in a stepwise manner.

[0062] (Second embodiment) FIG. 3 is a plan view showing an FSS loading member 102 according to the second embodiment. In the second embodiment, the description of the same configuration, action, and effect as in the first embodiment will be omitted or simplified by invoking the above description. In the FSS loading member 102 shown in FIG. 3, in a plan view of the FSS 25, the non-conductive portions 12 are formed in a lattice pattern, and the conductive portions 11 are formed in a rectangular patch pattern. The FSS 25 illustrated in FIG. 3 has seven rectangular cells 16 arranged in the first direction and three in the second direction, and the first region 10 is made up of 21 cells 16.

[0063] 3, in the FSS 25 corresponding to the first region 10, the widths of the conductive portions 11 in the first direction (X-axis direction) and the second direction (Y-axis direction) gradually decrease and the widths of the non-conductive portions 12 gradually increase as the FSS 25 approaches the second region 20 along the first direction, based on each cell 16 in a column 13 aligned in the second direction including the center of gravity G. On the other hand, in the FSS 25, the widths of the conductive portions 11 in the first direction (X-axis direction) and the second direction (Y-axis direction) are constant in the cells 16 along the second direction.

[0064] In this way, when the FSS 25 is configured such that the width in the first direction and the width in the second direction of the conductive portion 11 gradually decrease as it approaches the second region 20 along the first direction with respect to each cell 16 in the column 13, the transmission phase of the polarized waves in the first direction and the polarized waves in the second direction among the radio waves incident at a predetermined frequency F approaches the transmission phase of the second region 20. Therefore, the FSS loading member 102 according to this embodiment suppresses discontinuity in the transmission phase at the boundary between the first region 10 and the second region 20 in the first direction for the polarized waves in the first direction and the polarized waves in the second direction among the radio waves incident at a predetermined frequency F, mitigating changes in the intensity distribution of the radio waves transmitted through the FSS loading member 102 and suppressing distortion of the phase distribution.

[0065] (Third embodiment) FIG. 4 is a plan view showing an FSS loading member 103 according to the third embodiment. In the third embodiment, the description of the configuration, operation, and effects similar to those of the above-described embodiments will be omitted or simplified by incorporating the above description. In the FSS loading member 103 shown in FIG. 4, the shapes (outer edges) of the cells 16, which form the minimum unit area in a plan view of the FSS 35, are not identical. That is, in the FSS 35, the width of the cells 16 in the first direction gradually decreases as the cells 16 approach the second region 20 along the first direction, based on each cell 16 in a row 23 aligned in the second direction including the center of gravity G. The FSS 35 illustrated in FIG. 4 is composed of 21 rectangular cells 16, but the width in the first direction of each cell 16 in rows 24A and 24B aligned in the second direction adjacent to the second region 20 (in the first direction) is shorter than the width in the first direction of each cell 16 in the row 23. On the other hand, the width in the second direction of each cell 16 in each row aligned in the second direction in the FSS 35 is constant.

[0066] Furthermore, the FSS 35 has conductive portions 11 and non-conductive portions 12 for 21 cells 16. The closed loop shape of the non-conductive portion 12 surrounding the entire periphery of the conductive portion 11 of each cell 16 has a constant width in the first direction and a constant width in the second direction. These widths correspond to the distance between the outer edge of each cell 16 and the outer edge of the adjacent conductive portion 11. Note that at least one of the width in the first direction and the width in the second direction of the closed loop shape may be constant. Furthermore, when the width in the first direction and the width in the second direction of the closed loop shape are both constant, these widths may be the same or different. In this case, the widths of the non-conductive portion 12 disposed between two adjacent conductive portions 11 of two adjacent cells 16 are also constant in the first and second directions. The FSS loading member 103 of this embodiment differs from the above embodiment in that the size (outer edge) of each cell 16 in which the FSS 35 is arranged in the first region 10 varies, while the width (rectangular loop shape) of the non-conductive portion 12 of each cell 16 is constant.

[0067] In this way, when the FSS 35 is configured so that the width of the cells 16 in the first direction, and therefore the width of the conductive parts 11 in the first direction, gradually decreases as the FSS 35 approaches the second region 20, based on each cell 16 in the row 23, the transmission phase of the polarized waves in the first direction, among the radio waves incident at a predetermined frequency F, approaches the transmission phase of the second region. Therefore, the FSS loading member 103 according to this embodiment suppresses discontinuity in the transmission phase at the boundary between the first region 10 and the second region 20 in the first direction, for the polarized waves in the first direction, among the radio waves incident at a predetermined frequency F, and thus alleviates changes in the intensity distribution of the radio waves transmitted through the FSS loading member 103, thereby suppressing distortion of the phase distribution.

[0068] While the FSS loading member 103 according to this embodiment has been shown to have a configuration in which the width of each cell 16 in the first direction varies, a similar pattern to that in the first direction may also extend in the second direction. That is, the FSS loading member 103 according to this embodiment may be configured such that, with respect to the cell 16 including the center of gravity G as a reference, the widths of the cells 16 in the first direction and the second direction (and thus the width of the conductive portions 11 in the second direction) gradually decrease as the cell approaches the second region 20 along the first and second directions. In this case, the FSS loading member 103 in this configuration, like the FSS loading member 101 according to the first embodiment, suppresses discontinuity in the transmission phase at the boundary between the first region 10 and the second region 20 in the first direction for waves polarized in the first direction and waves polarized in the second direction among radio waves incident at a predetermined frequency F.

[0069] (Fourth embodiment) FIG. 5 is a plan view showing an FSS loading member 104 according to the fourth embodiment. In the fourth embodiment, the description of the same configuration, operation, and effect as those of the above-described embodiments will be omitted or simplified by incorporating the above description. In the FSS loading member 104 shown in FIG. 5, in a plan view of the FSS 45, the non-conductive portion 22 has a closed loop shape of a rectangular loop (loop slot shape), a conductive portion 21a is formed so as to surround the entire outer periphery of the non-conductive portion 22, and a conductive portion 21b is formed within the closed loop of the non-conductive portion 22. That is, in the FSS loading member 104 shown in FIG. 5, in a plan view of the FSS 45, the non-conductive portion 22 surrounded by the conductive portion 21a and the conductive portion 21b has a rectangular loop shape (loop slot shape). The conductive portion 21a and the conductive portion 21b are also referred to as the first conductive portion 21a and the second conductive portion 21b, respectively.

[0070] In FIG. 5 , the FSS 45 corresponding to the first region 10, with respect to each cell 16 in a column 13 aligned in the second direction including the center of gravity G, gradually decreases in width in the first direction (X-axis direction) and in the second direction (Y-axis direction) of the conductive portion 21b, and gradually increases in width of the non-conductive portion 22, as it approaches the second region 20 along the first direction. Note that each cell 16 of the FSS 45 constituting the first region is a minimum unit region having the same shape. Meanwhile, in the FSS 45, the widths in the first direction (X-axis direction) and in the second direction (Y-axis direction) of the first conductive portion 21a, the second conductive portion 21b, and the non-conductive portion 22 in each cell 16 along the second direction are constant. Note that the widths in the first direction and the second direction (Y-axis direction) of the outer edges of each cell 16 of the non-conductive portion 22 of the FSS 45 are constant.

[0071] In this way, when the FSS 45 is configured such that the widths of the rectangular loop slots of the non-conductive portion 22 in the first and second directions gradually increase and the widths of the conductive portion 21b in the first and second directions gradually decrease as one approaches the second region 20 along the first direction with respect to each cell 16 of the column 13, the transmission phases of the polarized waves in the first and second directions of the radio waves incident at a predetermined frequency F approach the transmission phase of the second region 20. Therefore, the FSS loading member 104 according to this embodiment suppresses discontinuity in the transmission phase at the boundary between the first region 10 and the second region 20 in the first direction for the polarized waves in the first and second directions of the radio waves incident at a predetermined frequency F, thereby mitigating changes in the intensity distribution of the radio waves transmitted through the FSS loading member 104 and suppressing distortion of the phase distribution.

[0072] In the FSS loading member 104 according to the embodiment, the width of the conductive portion 21b and the width of the rectangular loop slot of the non-conductive portion 22 change along the first direction for each cell 16. However, a similar pattern may also extend along the second direction. That is, the FSS loading member 104 according to the present embodiment may be configured such that the widths of the conductive portion 21b in the first direction and the second direction gradually decrease and the widths of the rectangular loop slot of the non-conductive portion 22 in the first direction and the second direction gradually increase as the FSS loading member 104 approaches the second region 20 along the first and second directions, using the center of gravity G as a reference. In this case, the FSS loading member 104 in this configuration, like the FSS loading member 101 according to the first embodiment, suppresses discontinuity in the transmission phase at the boundary between the first region 10 and the second region 20 in the first and second directions for waves polarized in the first and second directions among radio waves incident at a predetermined frequency F.

[0073] (Fifth embodiment) Fig. 6 is a plan view showing an FSS loading member 105 according to the fifth embodiment. In the fifth embodiment, the description of the same configuration, action, and effect as in the third embodiment will be omitted or simplified by invoking the above description. In the FSS loading member 105 shown in Fig. 6, in a plan view of the FSS 55, the non-conductive portion 22 surrounded by the first conductive portion 21a and the second conductive portion 21b is formed in a closed loop shape of a rectangular loop shape (loop slot shape).

[0074] 6, in the FSS 55 corresponding to the first region 10, the width in the first direction of the second conductive portion 21b gradually decreases and the width of the outer edge in the first direction of the non-conductive portion 22 gradually decreases as one approaches the second region 20 along the first direction, using each cell 16 in a column 23 aligned in the second direction including the center of gravity G as a reference. Note that the non-conductive portion 22 has a constant rectangular loop width. On the other hand, in the FSS 55, the second direction width of the first conductive portion 21a, the second direction width of the second conductive portion 21b, and the second direction width of the outer edge of the non-conductive portion 22 are all constant for each cell 16 along the second direction.

[0075] In this way, when the FSS 55 is configured such that the width of the conductive portion 21b in the first direction gradually decreases with increasing distance from each cell 16 of the column 23 including the center of gravity G, the transmission phase of the polarized waves in the first direction, among the radio waves incident at a predetermined frequency F, approaches the transmission phase of the second region 20. Therefore, the FSS loading member 105 according to this embodiment suppresses discontinuity in the transmission phase at the boundary between the first region 10 and the second region 20 in the first direction, for the polarized waves in the first direction, among the radio waves incident at a predetermined frequency F, and thus alleviates changes in the intensity distribution of the radio waves transmitted through the FSS loading member 105, thereby suppressing distortion of the phase distribution.

[0076] While the FSS loading member 105 according to the embodiment has been shown to have a configuration in which the width of the conductive portion 21b in the first direction varies for each cell 16, a similar pattern to that in the first direction may also extend in the second direction. That is, the FSS loading member 105 according to the present embodiment may be configured such that the width of the cell 16 in the first direction and the width of the conductive portion 21b in the first direction and the width of the conductive portion 21b in the second direction gradually decrease as the FSS loading member 105 approaches the second region 20 along the first and second directions, using the center of gravity G as a reference. In this case, the FSS loading member 105 in this configuration, like the FSS loading member 101 according to the first embodiment, suppresses discontinuity in the transmission phase at the boundary between the first region 10 and the second region 20 in the first and second directions for waves polarized in the first and second directions among radio waves incident at a predetermined frequency F.

[0077] (Sixth embodiment) FIG. 7 is a plan view showing an FSS loading member 106 according to a sixth embodiment. In the sixth embodiment, the description of the same configuration, operation, and effects as those of the above-described embodiments will be omitted or simplified by incorporating the above description. In the FSS loading member 106 shown in FIG. 7, in a plan view of the FSS 65, the non-conductive portion 32 has a closed-loop shape of a circular loop (ring loop slot shape), and the conductive portion 31a is formed so as to surround the entire outer periphery of the non-conductive portion 32, and the conductive portion 31b is formed within the closed-loop shape of the non-conductive portion 32. That is, in the FSS loading member 104 shown in FIG. 6, in a plan view of the FSS 65, the non-conductive portion 32 surrounded by the conductive portion 31a and the conductive portion 31b has a circular loop shape (ring loop slot shape). The conductive portion 31a and the conductive portion 31b are also referred to as the first conductive portion 31a and the second conductive portion 31b, respectively.

[0078] The non-conductive portion 32 may have an elliptical closed loop shape. In the FSS 65, the (virtual) region surrounded by the dashed line in the first region 10 shown in FIG. 7 is arranged two-dimensionally without gaps as regular hexagonal cells 36, which are the smallest unit region of the same shape. The center of the ring-loop slot-shaped non-conductive portion 32 coincides with the center of the regular hexagonal cell 36. In the FSS 65 shown in FIG. 7, the regular hexagonal cells 36 are arranged in a direction that forms an angle of 30° toward the second direction with respect to the first direction (X-axis direction) and in a direction that forms an angle of 30° toward the second direction (Y-axis direction), and the first region 10 is composed of 24 cells 36.

[0079] 7, in the FSS 65 corresponding to the first region 10, the width (in the first and second directions) of the first conductive portion 31a gradually increases and the width (diameter) (in the first and second directions) of the second conductive portion 31b gradually decreases as the FSS 65 approaches the second region 20 along the first direction, taking each cell 36 in a row 33 aligned in the second direction and including the center of gravity G or the cell 36 closest to the center of gravity G as a reference. Note that the non-conductive portion 32 has a constant width in the ring-loop slot shape. On the other hand, in the FSS 65, the sizes of the first conductive portion 31a, the second conductive portion 31b, and the non-conductive portion 32 in the cell 36 along the second direction are constant.

[0080] In this way, in the FSS 65, the widths in the first and second directions of the first conductive portion 31a gradually increase, and the widths in the first and second directions of the second conductive portion 31b gradually decrease, with respect to each cell 36 in the column 33 as the FSS 65 approaches the second region 20. Therefore, the FSS loading member 106 according to this embodiment suppresses discontinuity in the transmitted phase at the boundary between the first region 10 and the second region 20 in the first direction for polarized waves in the first direction and polarized waves in the second direction among radio waves incident at a predetermined frequency F, mitigating changes in the intensity distribution of radio waves transmitted through the FSS loading member 106 and suppressing distortion of the phase distribution.

[0081] Although the FSS loading member 106 according to the embodiment has been shown to have a configuration in which the width of the second conductive portion 31b varies along the first direction in each cell 36, a pattern similar to that in the first direction may also extend in the second direction. That is, the FSS loading member according to the embodiment may have a configuration in which the width of the second conductive portion 31b gradually decreases as it approaches the second region 20 along the first and second directions, using the center of gravity G or the cell 16 closest to the center of gravity G as a reference. In this case, the FSS loading member 106 in this configuration suppresses discontinuity in the transmission phase at the boundary between the first region 10 and the second region 20 in the first and second directions for waves polarized in the first and second directions among radio waves incident at a predetermined frequency F. [Example]

[0082] The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

[0083] [Radio wave penetration evaluation] In the examples and comparative examples shown below, the electromagnetic field was simulated when a plane wave equivalent to a radar wave with a frequency of 76.5 GHz was incident on the main surface of the FSS loading member from a direction perpendicular to the surface, and the transmission characteristics (S21) and electric field distribution were verified.

[0084] Example 1 FIG. 8 is a cross-sectional schematic diagram of an FSS loading member 107 according to Example 1. The FSS loading member 107 used 1.98 mm-thick soda lime glass for the dielectric substrates 51 and 52. The interlayer 53 was prepared as follows: a first interlayer 53A made of PVB with a thickness of 0.33 mm; and a second interlayer 53B made of PVB with a thickness of 0.43 mm. The FSS 70 was prepared as a laminate in which a conductor pattern 72 was formed on the main surface of a dielectric substrate 71 made of PET with a thickness of 0.10 mm, and the cells 16 were rectangular (square) in plan view. The FSS loading member 107 used a model in which the dielectric substrate 51, the first interlayer 53A, the FSS 70, the second interlayer 53B, and the dielectric substrate 52 were laminated in this order. The FSS 70 measured 24.96 mm × 24.96 mm in plan view. Table 1 also shows the conditions of each component of the FSS loading member (107) in Example 1 and Comparative Example 1 described later.

[0085] [Table 1]

[0086] 9 is an enlarged plan view of the FSS 70. Each cell 16 of the FSS 70 shown in FIG. 9 includes a square conductive portion 11, and has a square shape (indicated by a dashed line) that forms an outer edge along the center of the width of the non-conductive portion 12 that surrounds the conductive portion 11, with dimensions of (L = ) 0.24 mm × (L = ) 0.24 mm. In the enlarged plan view shown in FIG. 9, the length of one side of the square (indicated by a dashed line) formed by connecting the centers of gravity of eight cells 16 adjacent to the cell 16 located at the center is (P = ) 0.52 mm.

[0087] 10 is a diagram showing the distribution of cells 16 surrounded by dashed lines in a plan view of the FSS 70 in Example 1. In the FSS 70 in Example 1, the width of the gap (non-conductive portion 12) is gradually increased in stages with increasing distance from the center of gravity G, that is, the size of the conductive portion 11 is gradually decreased in stages with increasing distance from the center of gravity G. As shown in FIG. 10, the gap width is gradually increased in stages from the center of gravity G to 0.04 mm, 0.06 mm, 0.10 mm, and 0.20 mm. Therefore, the FSS 70 in Example 1 has a structure in which the pattern dimensions are changed so that the transmission phase changes toward the second region 20.

[0088] <Comparative Example 1> Fig. 11 is a plan view of the FSS in Comparative Example 1, which was a square of 24.96 mm x 24.96 mm, the same as in Example 1. In the FSS in Comparative Example 1, the cells 16 surrounded by the dashed lines were also (L = ) 0.24 mm x (L = ) 0.24 mm, the same as in Example 1, but the gap width was 0.04 mm, forming a lattice shape, and the pattern was uniform as shown in Fig. 11.

[0089] <Evaluation results> FIG. 12(a) shows the transmission phase of the FSS 70 having the pattern shown in Example 1 when the width Gap of the non-conductive portion 12 is changed. In FIG. 12(a), the horizontal axis represents the gap length, and the vertical axis represents the transmission phase. The transmission phase in the first region 10 having the FSS and the second region 20 not having the FSS are shown. The transmission phase in the second region 20 (dashed line) shown in FIG. 12(a) is a value independent of the gap. Furthermore, FIG. 12(b) shows the characteristics obtained by varying the difference in transmission phase (vertical axis) between the first region 10 and the second region 20 as the width Gap (horizontal axis) is changed. The results of FIGS. 12(a) and 12(b) indicate that the larger the width Gap of the non-conductive portion 12 in the first region 10, the closer the transmission phase becomes to that of the second region 20.

[0090] 13(a) and 13(b) respectively show the phase and effective value of the electric field on the outer main surface of the second dielectric substrate (second glass substrate) 52 on the transmission side (in FIG. 8) of the FSS loading member 107 of Example 1 and Comparative Example 1. The horizontal axis in each figure represents the dimension centered on the center of gravity G.

[0091] 13(a) and 13(b), in Example 1, the transmission phase of the FSS approaches the transmission phase in the second region 20 as it approaches from the first region 10 to the second region 20. In contrast, in Comparative Example 1, which is provided with a uniform FSS whose transmission phase does not change, the phase change of the electric field near the boundary between the first region 10 and the second region 20 is large, the overall ripple also becomes large, and it was found that distortion is likely to occur.

[0092] 14 and 15 are diagrams showing the electric field distribution when a plane wave is incident on the FSS loading member in Example 1 and Comparative Example 1. The plane wave incident on the FSS loading member (70) is incident from the direction of the arrow shown in Fig. 8, and the distribution of the transmitted electric field changes from moment to moment, but Fig. 14 and Fig. 15 each show the distribution of the instantaneous value of the electric field.

[0093] 13 (Example 1) and 14 (Comparative Example 1), it was found that Example 1 had smaller distortion of the wavefront transmitted through the FSS loading member 107 than Comparative Example 1. Therefore, it was confirmed that the FSS loading member 107 of Example 1 reduces the phase change of the electric field near the boundary between the first region 10 and the second region 20, thereby suppressing wavefront distortion and further suppressing ripples in the electric field intensity. [Explanation of symbols]

[0094] 10 First area 11 Conductive part 12, 22, 32 Non-conductive parts 15, 25, 35, 45, 55, 65, 70 Frequency Selective Surface (FSS) Rows 13, 23, 24A, 24B, 33 16, 36 cells 20 Second area 21a, 31a 1st conductive part 21b, 31b 2nd conductive part 50 Dielectric Substrate 51 First dielectric substrate (first glass substrate) 52 Second dielectric substrate (second glass substrate) 53 Interlayer 53A 1st interlayer film 53B 2nd interlayer film 61 Page 1 62 2nd page 63 3rd page 64 Page 4 65 Page 5 71 Dielectric substrate 72 Conductor Pattern 101, 102, 103, 104, 105, 106, 107 Frequency selective surface (FSS) loading members G center of gravity

Claims

1. a dielectric body; and a frequency selective surface that transmits radio waves of frequency F provided on the dielectric body; the frequency selective surface has a plurality of cells which are unit areas each including a conductive portion and a non-conductive portion, and the plurality of cells are two-dimensionally arranged without any gaps; When a first region having the frequency selective surface and a second region not having the frequency selective surface are defined in a plan view of the dielectric body, A frequency selective surface loading member, wherein the frequency selective surface has a pattern in which the transmission phase of the radio wave of frequency F changes to approach the transmission phase of the radio wave of frequency F in the second region as it approaches the second region in at least the first direction among a first direction and a second direction intersecting the first direction.

2. the frequency selective surface is such that the cell is formed by the non-conductive portion surrounding the entire periphery of one of the conductive portions, the non-conductive portion extends in the first direction and the second direction to form a lattice pattern; The frequency selective surface loading member according to claim 1 , wherein the width of the conductive portion in the first direction gradually decreases toward the second region.

3. The frequency selective surface loading member of claim 2 , wherein the widths of the cells extending in the first direction of the frequency selective surface are the same.

4. 3. The frequency selective surface loading member according to claim 2, wherein the width of the cells extending in the first direction of the frequency selective surface gradually decreases toward the second region.

5. The frequency selective surface loading member according to claim 2 , wherein the width of the cells extending in the second direction of the frequency selective surface gradually decreases toward the second region.

6. The frequency selective surface loading member according to claim 2 , wherein the cells of the frequency selective surface extending in the second direction have the same width.

7. The frequency selective surface loading member according to claim 2 , wherein the width of the conductive portions extending in the second direction of the frequency selective surface is the same.

8. The frequency selective surface loading member according to claim 2 , wherein the width of the conductive portion extending in the second direction of the frequency selective surface gradually decreases toward the second region.

9. The frequency selective surface loading member according to claim 2 , wherein the plurality of cells have the same width in the first direction of the non-conductive portion in a closed loop shape surrounding the entire periphery of the conductive portion.

10. The frequency selective surface loading member according to claim 9 , wherein the plurality of cells have the same width of the non-conductive portion in the second direction in the closed loop shape.

11. 11. The frequency selective surface loading member according to claim 9 or 10, wherein the closed loop shape is a rectangular loop shape.

12. the frequency selective surface is configured such that a plurality of the cells have the non-conductive portion in a closed loop shape inside an outer edge of the cell, and the conductive portion has a first conductive portion arranged outside the closed loop shape and a second conductive portion arranged inside the closed loop shape, and is arranged two-dimensionally without gaps; The frequency selective surface loading member according to claim 1 , wherein the width of the second conductive portion in the first direction gradually decreases toward the second region.

13. The frequency selective surface loading member of claim 12 , wherein the cells of the frequency selective surface extending in the first direction have the same width.

14. 13. The frequency selective surface loading member of claim 12, wherein the width of the cells extending in the first direction of the frequency selective surface gradually decreases toward the second region.

15. 15. The frequency selective surface loading member according to claim 12, wherein the width of the cells extending in the second direction of the frequency selective surface gradually decreases toward the second region.

16. 15. The frequency selective surface loading member according to claim 12, wherein the cells of the frequency selective surface extending in the second direction have the same width.

17. 17. The frequency selective surface loading member according to claim 12, wherein the width of the second conductive portion extending in the second direction of the frequency selective surface is the same.

18. 17. The frequency selective surface loading member according to claim 12, wherein the width of the second conductive portion extending in the second direction of the frequency selective surface gradually decreases toward the second region.

19. 19. The frequency selective surface loading member of claim 12, wherein the closed loop shape is a rectangular loop shape.

20. the frequency selective surface is configured such that a plurality of the cells have the non-conductive portion in a circular or elliptical closed loop shape inside an outer edge of the cell, the conductive portion has a first conductive portion arranged outside the closed loop shape and a second conductive portion arranged inside the closed loop shape, and is arranged two-dimensionally without gaps, The frequency selective surface loading member according to claim 1 , wherein the width of the second conductive portion in the first direction gradually decreases toward the second region.

21. 21. The frequency selective surface loading member of claim 20, wherein the width of the second conductive portion in the second direction of the frequency selective surface is the same.

22. 21. The frequency selective surface loading member according to claim 20, wherein the width of the second conductive portion in the second direction of the frequency selective surface gradually decreases toward the second region.

23. 23. The frequency selective surface loading member of claim 1, wherein the frequency selective surface is point symmetric with respect to the center of gravity of the first region.

24. The dielectric includes a first glass substrate, a second glass substrate, and 24. The frequency selective surface loading member of claim 1, further comprising one or more interlayers sandwiched between the first and second glass substrates.

25. the interlayer film includes a first interlayer film and a second interlayer film, 25. The frequency selective surface loading member of claim 24, wherein the frequency selective surface is disposed between the first interlayer and the second interlayer.

26. 26. The frequency selective surface loading member according to claim 24 or 25, wherein the dielectric is a laminated glass for a vehicle.

27. 27. The frequency selective surface loading member according to any one of claims 1 to 26, wherein the frequency F is comprised in the range of 1 GHz to 100 GHz.

28. 28. A window member for a vehicle comprising a frequency selective surface loading member according to any one of claims 1 to 27.

29. 30. The vehicle window component of claim 28, wherein the frequency selective surface loading component is a windshield for the vehicle.

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