Electromagnetic wave reflection device, electromagnetic wave reflection fence, and method for assembling electromagnetic wave reflection device

Abstract

Provided is an electromagnetic wave reflection device with which it is possible to achieve both improvement in a radio wave propagation environment and improvement in weather resistance, and a corresponding electromagnetic wave reflection fence and method for assembling an electromagnetic wave reflection device. This electromagnetic wave reflection device (10) includes: a panel (13) having a reflection surface (105) that reflects radio waves in a desired band selected from a frequency band of 1 MHz-300 GHz; and a support body (11) that supports the panel (13) and is made of a conductive material. The support body (11) has a conductive part (115) that is electrically connected to the panel (13), and an insulating film (112) formed on at least a part of a portion other than the conductive part (115).

Description

Electromagnetic Wave Reflection Device, Electromagnetic Wave Reflection Fence, and Assembly Method of Electromagnetic Wave Reflection Device

[0001] The present disclosure relates to an electromagnetic wave reflection device, an electromagnetic wave reflection fence, and an assembly method of the electromagnetic wave reflection device.

[0002] Base stations have been introduced into factories, plants, offices, commercial facilities, etc. due to the introduction of automation in manufacturing processes and office work, or the introduction of control and management by AI (Artificial Intelligence). In the fifth-generation mobile communication system (5G), frequency bands of 6 GHz or less called sub-6 and a 28 GHz band classified as a millimeter-wave band are provided. In the next-generation sixth-generation mobile communication system (6G), an expansion to the sub-terahertz band is expected. By using such high-frequency bands, the communication bandwidth is significantly expanded, and a large amount of data communication is performed with low latency. A configuration has been proposed in which an electromagnetic wave reflection device is arranged together with a base station in factories, plants, offices, commercial facilities, etc. to reduce spots where the base station antenna cannot be seen (NLOS: Non-Line-Of-Sight) (see, for example, Patent Document 1).

[0003] International Publication No. 2021 / 199504

[0004] In various facilities such as factories, plants, offices, commercial facilities, etc., there are obstacles such as various devices and structures, and it is difficult to maintain high communication quality. By using an electromagnetic wave reflection device, NLOS spots can be reduced and the radio wave propagation environment can be improved, but it is desirable to cover a wide communication environment according to the area of the facility. To cover a large area, a large-area electromagnetic wave reflection device is required, but substrates such as resin and glass are limited in size to about several meters due to restrictions on manufacturing equipment and ease of handling constraints. Therefore, a plurality of panels are connected via a frame or the like to form a large area.

[0005] In order for an electromagnetic wave reflection device composed of a panel and a frame to exhibit uniform reflection characteristics, it is desirable to make the reference potentials of reflection of the reflection surfaces of the plurality of panels held by the frame continuous.

[0006] Incidentally, if the frame is made of conductive material to maintain a continuous reference potential for reflection between the reflective surfaces of multiple panels, durability issues arise regarding rust and corrosion of the metal parts when the electromagnetic wave reflector is placed in an environment exposed to wind and rain, such as outdoors. Furthermore, durability issues arise not only in environments exposed to wind and rain, such as outdoors, but also in indoor environments close to outdoors or when used indoors.

[0007] This disclosure aims to provide an electromagnetic wave reflecting device, an electromagnetic wave reflecting fence, and a method for assembling an electromagnetic wave reflecting device that achieve both improved radio wave propagation environment and improved weather resistance.

[0008] An electromagnetic wave reflecting device according to one aspect of the present disclosure includes a panel having a reflective surface that reflects radio waves in a desired frequency band selected from the frequency band of 1 MHz to 300 GHz, and a support made of a conductive material that supports the panel, wherein the support has a conductive portion that is in electrical contact with the panel and an insulating film formed on at least a portion of the portion other than the conductive portion.

[0009] This invention provides an electromagnetic wave reflector, an electromagnetic wave reflector fence, and a method for assembling an electromagnetic wave reflector that achieve both improved radio wave propagation conditions and improved weather resistance.

[0010] This is an example of a schematic diagram of radio wave propagation using the electromagnetic wave reflector of the embodiment. This diagram illustrates an example of reflection at the same reflection angle as the incidence angle. This diagram illustrates an example of reflection at a different reflection angle than the incidence angle. This diagram illustrates an example of diffusion in multiple directions. This diagram shows an example of the basic configuration of the electromagnetic wave reflector of the embodiment. This diagram shows an example of an electromagnetic wave reflecting fence made up of multiple panels connected together. This diagram shows an example of the frame configuration. This diagram shows another example of the frame configuration. This diagram shows yet another example of the frame configuration. This diagram shows yet another example of the frame configuration. This diagram shows an example of the panel configuration. This diagram shows another example of the panel configuration. This diagram shows yet another example of the panel configuration. This diagram shows yet another example of the panel configuration. This diagram shows an example of the edge treatment of the panel. This diagram shows a modified version of the electromagnetic wave reflector. This diagram shows another modified version of the electromagnetic wave reflector. This diagram shows yet another modified version of the electromagnetic wave reflector. This is a modified version of an electromagnetic wave reflecting fence made up of multiple panels connected together. This diagram illustrates an example of a method for evaluating reflection characteristics. This diagram illustrates an example of the analysis space for reflection characteristics. This diagram illustrates an example of the analysis space for reflection characteristics.

[0011] <Overall System Overview> Figure 1 is an example of a schematic diagram of radio wave propagation using the electromagnetic wave reflector 10 of the embodiment. Radio waves are a type of electromagnetic wave, and generally, electromagnetic waves below 3 THz are called radio waves. Hereinafter, electromagnetic waves radiated from a base station or relay station will be referred to as "radio waves," and when referring to electromagnetic waves in general, the term "electromagnetic wave" will be used. In the figure, the same elements may be given the same symbols to omit redundant explanations.

[0012] The electromagnetic wave reflector 10 is located in the service area SA provided by the base station BS. The height direction of the space where radio waves are transmitted and received between the base station BS and the reflector is defined as the Z direction, and the plane perpendicular to the Z direction is defined as the X-Y plane. The base station BS is installed indoors or outdoors, and the service area SA can be formed in places such as streets, shopping malls, production lines in factories, and event venues.

[0013] A base station (BS) transmits and receives radio waves in a specific frequency band, for example. Radio waves emitted from a base station (BS) are reflected, shielded, and weakened by building walls and street trees. In factory production lines, radio waves are reflected, weakened, and shielded by metal equipment, ducts, pipes, and other structures. High-frequency radio waves, such as those in the millimeter wave band, have strong directivity and little diffraction, so they may have difficulty reaching terminal equipment in service areas (SAs).

[0014] The electromagnetic wave reflector 10 has a reflective surface 105 that reflects radio waves in a specific frequency band, and propagates radio waves from the base station BS to terminal devices within the service area SA. The specific frequency band of radio waves transmitted and received by the base station BS and the specific frequency band of radio waves reflected by the electromagnetic wave reflector 10 are, for example, 1 MHz to 300 GHz, preferably 1 GHz to 100 GHz, and more preferably 1 GHz to 80 GHz.

[0015] The location of the electromagnetic wave reflector 10 is not limited to the example in Figure 1. The electromagnetic wave reflector 10 can be placed in an appropriate location depending on the location of the base station BS, the surrounding environment, the conditions within the service area SA, etc. For example, multiple electromagnetic wave reflectors 10 may be placed facing each other or in an alternating pattern with the service area SA in between. As will be described later, multiple electromagnetic wave reflectors can also be connected.

[0016] The reflective surface 105 of the electromagnetic wave reflector 10 has at least one of a normal reflector 101 and a metal reflector 102. The normal reflector 101 provides normal reflection to the incident electromagnetic wave, where the angle of incidence and the angle of reflection are equal. The metal reflector 102 has an artificial surface that controls the reflection characteristics of the incident electromagnetic wave. A "metal reflector" is a type of "metasurface" which means an artificial surface that controls the transmission and reflection characteristics of the incident electromagnetic wave. In the metal reflector 102, by arranging a large number of scatterers that are sufficiently small compared to the wavelength and controlling the reflection phase distribution and amplitude distribution, electromagnetic waves are reflected in a predetermined direction other than normal reflection. The metal reflector 102 not only reflects in directions other than normal reflection, but also achieves diffusion with a predetermined angular distribution and wavefront formation.

[0017] Figures 2A to 2C show an example of reflection at the reflective surface 105 of the electromagnetic wave reflector 10. In Figure 2A, electromagnetic waves incident on the normal reflector 101 are reflected at the same reflection angle θref as the incident angle θin. In Figure 2B, electromagnetic waves incident on the metal reflector 102a are reflected at a reflection angle θref that is different from the incident angle θin. The absolute value of the difference between the reflection angle θref by the metal reflector 102 and the reflection angle due to normal reflection may be called the abnormal angle θabn. As described above, by arranging a metal patch or the like that is sufficiently smaller than the wavelength used on the surface of the metal reflector 102a to form a surface impedance, the reflection phase distribution can be controlled and incident electromagnetic waves can be reflected in a desired direction.

[0018] The electromagnetic waves reflected by the metal reflector 102 do not have to be plane waves with a single reflection angle. In Figure 2C, by devising the surface impedance formed on the surface of the metal reflector 102b, the incident electromagnetic waves are diffused in multiple directions with multiple different reflection angles. As a method for realizing the reflection in Figure 2C, for example, there is the method described in PHYSICAL REVIEW B 97, "ARBITRARY BEAM CONTROL USING LOSSLESS METASURFACES ENABLED BY ORTHOGONALLY POLARIZED CUSTOM SURFACE WAVES". The intensity of the diffused electromagnetic waves may be uniform, or it may have a predetermined intensity distribution depending on the reflection direction.

[0019] <Configuration of Electromagnetic Wave Reflector and Electromagnetic Wave Reflecting Fence> Figure 3 shows an example of the basic configuration of the electromagnetic wave reflector 10 of the embodiment. The electromagnetic wave reflector 10 has a panel 13 having a reflective surface 105 that reflects radio waves in a desired band selected from the frequency band of 1 MHz to 300 GHz, and a frame 11 that supports the panel 13. The frame 11 is an example of a support.

[0020] The frame 11 has a relative ratio of its resistance value after performing a salt spray test in accordance with JIS Z 2371 to its resistance value before the test, which is 1.00 or more and 1000.00 or less.

[0021] The electromagnetic wave reflector 10 may be used in environments exposed to wind and rain, such as outdoors, or in indoor environments that are close to the outdoors. An indoor environment that is close to the outdoors is, for example, an indoor environment that is close to an entrance or exit to the outdoors and is susceptible to the effects of wind and rain. Furthermore, even when used indoors, not limited to environments exposed to wind and rain, such as outdoors, or indoor environments that are close to the outdoors, the device may be exposed to water, water droplets due to condensation, or chemicals.

[0022] In such cases, rust and corrosion may occur on the metal parts of the frame 11, leading to durability issues. Therefore, the frame 11 of the electromagnetic wave reflector 10 has a configuration in which the relative ratio of the resistance value after performing a salt spray test in accordance with JIS Z 2371 to the resistance value before performing the test is between 1.00 and 1000.00.

[0023] Furthermore, the electromagnetic wave reflector 10 has the strength to withstand tests compliant with the pendulum test of ISO 14120, which involves impacting the pendulum with an energy of E = 115 J or more.

[0024] For example, one possible application is to reduce NLOS spots by placing the electromagnetic wave reflector 10 along the path of an autonomous mobile robot such as an AMR (Autonomous Mobile Robot) and reflecting radio waves containing the AMR's control signals emitted from the base station's antenna.

[0025] ISO 3691-4 is an international standard for the safe operation of AMRs, but there may be environments where the safety conditions of ISO 3691-4 cannot be met. ISO 3691-4 stipulates that guards should be installed around AMR walkways to ensure cooperation between AMRs and humans and to guarantee safety.

[0026] In such cases, if the electromagnetic wave reflector 10 has the strength to meet the requirements of the pendulum test of ISO 14120, it is possible to achieve both improvement of the radio wave propagation environment and assurance of safety. For this reason, the electromagnetic wave reflector 10, as an example, has the strength to meet the requirements of the pendulum test of ISO 14120. This is to separate the AMR passage from the area reserved for humans, thereby realizing cooperation between AMR and humans and ensuring safety, as well as improving the radio wave propagation conditions in the AMR passage.

[0027] Furthermore, the electromagnetic wave reflector 10 has a ratio of 0.8 or higher of the main peak intensity of the scattering cross-section of an electromagnetic wave reflector 10 including two panels 13-1 and 13-2 supported by a frame 11 to the main peak intensity of the scattering cross-section of an electromagnetic wave reflector 10 consisting of a single panel 13 without using a frame 11 (ratio of main peak intensity of scattering cross-section). This is to ensure good reflection characteristics as an electromagnetic wave reflector 10.

[0028] The salt spray test according to JIS Z 2371 and the pendulum test according to ISO 14120 will be described later using the test results. The evaluation method for the main peak intensity ratio of the scattering cross-section will also be described later. Here, we will first describe the configuration of the electromagnetic wave reflector 10.

[0029] As described above, the reflective surface 105 of the panel 13 is formed of at least one of a normal reflector 101 that performs normal reflection and a meta reflector 102 that has an artificial surface that controls the reflection characteristics of incident electromagnetic waves. The normal reflector 101 may include a reflective surface formed of an inorganic conductive material or a conductive polymer material.

[0030] The material, surface shape, and manufacturing method of the metal reflector 102 are not limited, as long as it can reflect incident electromagnetic waves in a desired direction or diffuse them in a desired angular distribution. Generally, a metasurface can be obtained by forming a metal patch sufficiently smaller than the wavelength of use on the surface of a conductor such as a metal, via a dielectric layer. The metal reflector 102 is formed to have the desired reflection characteristics according to the design conditions for the direction in which the electromagnetic waves should be reflected, and is placed at an appropriate position on the reflective surface 105.

[0031] The size of the panel 13 can be appropriately designed depending on the environment in which it will be used. For example, the width w of the panel 13 may be 0.5 m to 3.0 m, the height h may be 1.0 m to 2.5 m, and the thickness t may be 3.0 mm to 9.0 mm. Considering the ease of transporting the electromagnetic wave reflector 10 to its installation site and the ease of assembly, the size w x h x t of the panel 13 may be approximately 1.0 m x 2.0 m x 5.0 mm. Part of the panel 13 may be transparent to visible light.

[0032] The panel 13 is supported by the frame 11. The frame 11 has a frame body 111 that has mechanical strength to stably hold the panel 13. The electromagnetic wave reflector 10 may be used individually, or multiple electromagnetic wave reflectors 10 may be connected to be used as an electromagnetic wave reflecting fence. In addition to mechanical strength, the frame body 111 has a structure suitable for connecting the reflective surfaces 105 of multiple panels 13. The specific configuration of the frame body 111 will be described later with reference to Figures 5A to 5D.

[0033] When the electromagnetic wave reflector 10 is installed indoors or outdoors, it may be attached to a wall or the like by the frame 11. As will be described later, the frame 11 is formed in a light and thin shape while having sufficient strength, making it suitable for installation on walls and the like. The panel 13 and the frame 11 are detachable and can be transported separately to the installation site. The electromagnetic wave reflector 10 can be assembled at the installation site and placed in the desired location.

[0034] Figure 4 is a schematic diagram of an electromagnetic wave reflective fence 100 formed by connecting multiple electromagnetic wave reflectors 10. The electromagnetic wave reflective fence 100 is assembled by connecting panels 13-1 and 13-2 with a frame 11. The frame 11 has a frame body 111 that grips the ends of panels 13-1 and 13-2. The frame body 111 has a configuration that connects the potential surface of the reflection occurring at the reflective surface 105 of panel 13-1 with the potential surface of the reflection occurring at the reflective surface 105 of panel 13-2. When panels 13-1 and 13-2 are used in connection, if the reflected current flowing due to the incidence of electromagnetic waves is blocked between adjacent panels 13-1 and 13-2, the energy of the reflected electromagnetic waves will be attenuated. In addition, reflected electromagnetic waves may be radiated in an unwanted direction, which may degrade communication quality.

[0035] To ensure the continuity of the reflected current between adjacent panels 13-1 and 13-2, it is desirable that the frame 11 transmits the reference potential for reflection from one panel to the other at high frequency, so that the reference potential generated by the reflection phenomenon is shared between adjacent panels. As long as the reference potential for the reflection phenomenon is continuous between adjacent panels 13-1 and 13-2, the number of connected panels 13 is not limited to two, and three or more panels 13 may be connected by the frame 11. As described above, each panel 13 and frame 11 are detachable and can be transported separately and assembled at the installation site to create the electromagnetic wave reflection fence 100. In that case, the end of the outermost panel of the multiple consecutive panels 13 may be covered with a protective jacket made of plastic or the like instead of the frame 11.

[0036] When multiple panels 13 are connected, it is desirable that the continuity of the reflected current be as uniform as possible throughout the frame body 111 of the frame 11.

[0037] <Assembly Method of Electromagnetic Wave Reflector 10> Here, we will explain how to assemble the electromagnetic wave reflector 10.

[0038] First, a panel 13-1 having a first reflective surface that reflects radio waves in a desired frequency band selected from the frequency band of 1 MHz to 300 GHz, a panel 13-2 having a second reflective surface that reflects radio waves in the same frequency band, and a frame 11 made of a conductive material that supports panels 13-1 and 13-2 are prepared. The frame 11 has conductive portions 115 that are electrically connected to panels 13-1 and 13-2, and an oxide film 112 formed on at least a portion of the parts other than the conductive portions 115.

[0039] Then, by inserting panels 13-1 and 13-2 into the recesses 113 of the frame 11, the frame 11 supports them, and electrical connection is established between panels 13-1 and 13-2 and the conductive portion 115. By mechanically connecting panels 13-1 and 13-2 with the frame 11, a continuous reference potential for reflection is established between the first reflective surface and the second reflective surface (the reflective surfaces of panels 13-1 and 13-2). With this, the electromagnetic wave reflecting device 10 is completed.

[0040] Next, specific examples of the frame 11's configuration will be described using Figures 5A to 5D.

[0041] Figure 5A is a schematic diagram showing an example of the configuration of frame 11A. Frame 11A is depicted in a horizontal cross-section along the thickness direction of the supporting panel 13. Frame 11A has a frame body 111 made of a conductor, an oxide film 112, a recess 113, a hollow portion 114, and a conductive portion 115.

[0042] The frame body 111 is, for example, made of lightweight aluminum with high electrical conductivity, but it may be made of a metal other than aluminum. The metal material (conductive material) of the frame body 111 should be a metal with an electrical conductivity of 30.0 IACS% or higher. The frame body 111 is defined as having a width (W) direction parallel to the reflective surface 105 of the panel 13 to be supported, and a thickness (T) direction parallel to the thickness of the panel 13.

[0043] The frame body 111 has recesses 113 at both sides in the width direction (X direction) into which the ends of the panel 13 are inserted, and has a hollow portion 114 independent of the two recesses 113 between the two recesses 113. "Independent" from the two recesses 113 means that it does not communicate with either of the two recesses 113. The hollow portion 114 contributes to the weight reduction of the frame body 111. The frame body 111 has an outer surface 116. The outer surface 116 is the surface visible from the outside of the frame body 111 and is the surface excluding the inner surfaces of the recesses 113 and the hollow portion 114.

[0044] As will be described later, the thickness T of the frame body 111 is set to a thickness such that the entire frame 11A has sufficient strength. Generally, increasing the thickness T of the frame body 111 increases the rigidity, but if the frame body 111 is too thick, it becomes difficult to satisfy the desired electromagnetic wave reflection characteristics and the requirements of being thin and lightweight. The thickness T of the frame body 111 is 1.0 mm to 10.0 mm, preferably 1.5 mm to 7.5 mm, more preferably 2.0 mm to 5.0 mm. In this specification, when using "~" to represent a range, it includes the lower limit value and the upper limit value. That is, 2.0 mm to 5.0 mm means 2.0 mm or more and 5.0 mm or less. By setting the thickness of the frame body 111 within the above-described range, it is possible to provide sufficient rigidity without increasing the size of the frame body 111 and to make the reference potential of reflection common between adjacent panels 13.

[0045] As will be described later, the frame body 111 having the recesses 113 securely holds the ends of the panel 13 by surface contact, and makes the reflection potentials of the reflection surface 105 of one panel 13-1 and the reflection surface 105 of the other panel 13-2 continuous. When a reflection current occurs in one panel 13-1, the reflection current flows through the frame body 111 and into the conductor constituting the reflection surface 105 of the other panel 13-2. By using such a frame body 111, the reflection current flows through a short current path, there is little current loop, and the reflection performance is good.

[0046] The width W of the frame body 111 is preferably 20 mm to 100 mm, and more preferably 35 mm or more and 70 mm or less, from the viewpoint of securely gripping adjacent panels 13 and sharing a common potential plane for reflection between adjacent panels 13. The thickness of the frame body 111 is greater than the thickness of the panels 13, and the difference between the thickness of the frame body 111 and the thickness of the panels 13 is preferably 5.0 mm or more and 20.0 mm or less, and preferably 7.0 mm or more and 15.0 mm or less. As an example, the gap G of the recess 113 and the hollow portion 114 is both 5.5 mm. In practice, the width W of the frame body 111 includes the thickness of the oxide film 112, but since the thickness of the oxide film 112 is negligibly small compared to the width of the frame body 111 in the X direction, the width W of the frame body 111 includes the thickness of the oxide film 112. The same applies to the thickness T of the frame body 111 in the Y direction.

[0047] The oxide film 112 is a film formed by oxidizing the surface of the metal constituting the frame body 111. The oxide film 112 is formed to suppress rust and corrosion of the metal constituting the frame body 111 and to improve the durability of the electromagnetic wave reflector 10. The oxide film 112 is transparent to radio waves in a desired frequency band that the electromagnetic wave reflector 10 reflects. "Transparent" to radio waves in a desired frequency band means that it transmits 50% or more of the radio waves in the desired frequency band, preferably 60% or more, and more preferably 70%. As an example, if the frame body 111 is made of aluminum, the oxide film 112 is an anodized film. An anodized film can be formed by oxidizing the surface of aluminum. Here, as an example, the case in which an uncolored white oxide film 112 (anodized coating) is used will be described. Also, the thickness of the oxide film 112 is, as an example, 1.0 μm or more and 50.0 μm or less. By covering the outer surface 116 of the frame body 111 with an oxide film 112, abnormal scattering on the outer surface of the frame 11A can be suppressed.

[0048] The oxide film 112 is formed on the portion excluding the portion (hereinafter referred to as the inner part 113B) where the width in the Y direction on the inner side of the recess 113 is narrowed as shown in FIG. 5A as an example, and on the outer surface 116. For this reason, the inner part 113B of the recess 113 is not covered with the oxide film 112, and the metal of the frame body 111 is exposed. A conduction part 115 is provided on a plane parallel to the YZ plane at the deepest part of the inner part 113B of the recess 113. The conduction part 115 is the deepest part of the recess 113 and is a part parallel to the XZ plane. The inner part 113B of the recess 113 is a part where the width in the Y direction is equal to that of the conduction part 115. The oxide film 112 is formed on the portion excluding the inner part 113B and the conduction part 115 of the inner surface of the recess 113.

[0049] Both corner portions on both sides in the width (W) direction of the frame body 111 covered with the oxide film 112 may be chamfered with a predetermined radius of curvature R. Being chamfered with R means that an R processing is performed and the corner portions are formed to be rounded and curved. By performing R chamfering on the corner portions of the frame body 111, abnormal scattering at the corner portions can be suppressed. The radius of curvature R is, as an example, 0.1 mm or more, preferably 0.5 mm or more, more preferably 1 mm or more, and has a radius of curvature of 3 mm or less, preferably 2.5 mm or less, more preferably 2.0 mm or less.

[0050] The recess 113 is a portion recessed from both end sides (the -X direction side and the +X direction side) in the X direction of the frame body 111 toward the center side of the width of the frame body 111 in the X direction. The width of the recess 113 in the Y direction is the largest (gap G) at the center of the length in the X direction, and is narrowed at the entrance 113A of the recess 113 and the inner part 113B located on the inner side. The widths in the Y direction of the entrance 113A of the recess 113 and the inner part 113B are equal.

[0051] The width of the entrance 113A of the recess 113 in the Y direction is approximately equal to the thickness of the panel 13 in the Y direction, and the panel 13 is supported by the entrance 113A and the back portion 113B when it is inserted into the recess 113. When the panel 13 is inserted into the recess 113, there is almost no gap between the entrance 113A and the back portion 113B and the panel 13. Therefore, by inserting the panel 13 into the recess 113, the panel 13 is fixed to the frame body 111.

[0052] The conductive portion 115 is located on the inner surface of the recess 113, at the innermost part of the recess 113, and is parallel to the YZ plane. The conductive portion 115 is not covered by the oxide film 112, and the metal of the frame body 111 is exposed. The width of the conductive portion 115 in the Y direction is, for example, equal to the width of the entrance of the recess 113 in the Y direction.

[0053] The conductive portion 115 is provided to establish electrical contact with the reflective surface 105 of the panel 13. When the panel 13 is inserted into the recess 113, the conductor on the end face parallel to the YZ plane at the X-direction end of the panel 13 comes into contact with it. This allows the reference potentials of panels 13-1 and 13-2 to be continuous.

[0054] Figure 5B is a schematic diagram showing an example of the configuration of frame 11B. Frame 11B has the same configuration as frame 11A shown in Figure 5A, but the radius of curvature R of the R-chamfered corners is smaller than that of frame 11A. Except for the smaller radius of curvature R of the R-chamfered corners, frame 11B has the same configuration as frame 11A.

[0055] In such a frame 11B, when the panel 13 is inserted into the recess 113, the conductor on the end face of the panel 13 parallel to the YZ plane at the X-direction end comes into contact with the conductive portion 115. This allows the reference potentials of panels 13-1 and 13-2 to be made continuous.

[0056] Figure 5C is a schematic diagram showing an example of the configuration of frame 11C. Frame 11C has the same configuration as frame 11A shown in Figure 5A, but compared to frame 11A, the area in which the oxide film 112 is formed inside the recess 113 is larger.

[0057] In frame 11C, the oxide film 112 is formed inside the recess 113, excluding the conductive portion 115 located at the innermost part of the recess 113. In such a frame 11C, when panel 13 is inserted into the recess 113, the conductor on the end face parallel to the YZ plane at the X-direction end of panel 13 comes into contact with the conductive portion 115. Therefore, the reference potentials of panels 13-1 and 13-2 can be made continuous.

[0058] Figure 5D is a schematic diagram showing an example of the configuration of frame 11D. Frame 11D has a similar configuration to frame 11A shown in Figure 5A, but the area in which the oxide film 112 is formed is smaller compared to frame 11A.

[0059] In frame 11D, the oxide film 112 is not formed on the inner surface of the recess 113. In frame 11D, the oxide film 112 covers the entire outer surface 116.

[0060] Even when using such a frame 11D, as with the cases where frames 11A to 11C are used, when the panel 13 is inserted into the recess 113, the conductor on the end face parallel to the YZ plane at the X-direction end of the panel 13 comes into contact with the conductive portion 115. Therefore, the reference potentials of panels 13-1 and 13-2 can be made continuous.

[0061] As described above, in any of the frames 11A to 11D shown in Figures 5A to 5D, panels 13-1 and 13-2 can be supported with sufficient strength by gripping the ends of the panels 13-1 and 13-2 with the recesses 113 formed in the frame body 111. In addition, by having the end face of panel 13 abut against the conductive portion 115, the reflected current or the reference potential of reflection can be made common between adjacent panels 13-1 and 13-2.

[0062] It is preferable that the oxide film 112 is formed on the entire outer surface 116 of the frame body 111, but it is sufficient if it is formed on at least a part of the outer surface 116 and the surface of the interior of the recess 113 excluding the conductive portion 115. This is because forming it on at least a part can suppress rust and corrosion of the metal constituting the frame body 111 in that at least part, thereby improving the durability of the electromagnetic wave reflector 10.

[0063] Furthermore, although the above describes a configuration in which the frame 11 supports the left and right ends of the panel 13, the frame 11 may also be provided at the upper or lower end of the panel 13, in addition to the left and right ends. The entire surface of the frame 11 provided at the upper or lower end may be covered with an oxide film 112. If the frame 11 provided at the upper or lower end is made of aluminum, the entire surface may be covered with an anodized film.

[0064] Figures 6A to 6D show examples of the configuration of panel 13. In Figure 6A, panel 13A has a reflective surface 105 of a conductor 131. The reflective surface 105 can have any configuration as long as it is a surface that reflects electromagnetic waves in the range of 1 MHz to 300 GHz. For example, the reflective surface 105 can be formed by a mesh conductor, a conductive film, a combination of transparent resin and a conductive film, etc., that reflects electromagnetic waves in any frequency band selected from the range of 1 MHz to 300 GHz.

[0065] By designing the reflective surface 105 to reflect radio waves in a desired frequency band between 1 MHz and 300 GHz, it is possible to cover the main frequency bands currently used in mobile communications in Japan, such as the 1.5 GHz band and the 2.5 GHz band. The next generation of 5G communication networks is planned to include the 4.5 GHz band and the 28 GHz band. In other countries, the 2.5 GHz band, 3.5 GHz band, 4.5 GHz band, the 24-28 GHz band, and the 39 GHz band are planned as 5G frequency bands. It can also support 52.6 GHz, the upper limit of the millimeter-wave frequency band for the 5G standard. In the future, if terahertz band mobile communications are realized indoors, the reflection bandwidth of the reflective surface 105 may be extended to the terahertz band by applying photonic crystal technology, etc.

[0066] The conductor 131 does not have to be a homogeneous conductive film, as long as it can reflect 30% or more of the radio waves in the 1 MHz to 300 GHz range. For example, it may be a mesh, grid, or arrangement of holes formed to a density that reflects electromagnetic waves in the above frequency band. The repeating pitch, which is related to the density that reflects the desired electromagnetic waves, may be uniform or non-uniform. The repeating period, or its average period, is preferably 1 / 5 or less of the wavelength of the target frequency, and more preferably 1 / 10 or less.

[0067] Figure 6B shows an example of the configuration of panel 13B. Panel 13B is a normal reflector and has a laminated structure of a conductor 131 and a dielectric 132 that is transparent to the operating frequency. Either surface of the conductor 131 becomes the reflective surface 105. When electromagnetic waves are incident from the conductor 131 side, the interface between the conductor 131 and the air becomes the reflective surface 105. When electromagnetic waves are incident from the dielectric 132 side, the interface between the conductor 131 and the dielectric 132 becomes the reflective surface 105.

[0068] The dielectric 132 that holds the conductor 131 or covers the surface of the conductor 131 should have sufficient rigidity to withstand vibration and preferably meet the safety requirements of ISO 014120 of the International Organization for Standardization. When used outdoors or in a factory, it should be able to withstand impact and provide protection even if an object hits it. It is also preferable that it be transparent in the visible light range. As an example, optical plastics, reinforced plastics, reinforced glass, etc., with a strength of a certain level or higher can be used. As optical plastics, polycarbonate (PC), polymethyl methacrylate (PMMA), polystyrene (PS), etc. may be used.

[0069] Figure 6C shows an example of the configuration of panel 13C. Panel 13C has a conductor 131 sandwiched between two dielectrics 132. Depending on the direction of incidence of electromagnetic waves, the interface between the conductor 131 and either dielectric becomes a reflective surface 105. The required rigidity of the two dielectrics 132 is the same as in the configuration of Figure 6B.

[0070] Figure 6D shows an example of the configuration of panel 13D. A metal reflector 102 may be provided on a part of the laminate in Figure 6B. The laminate of conductor 131 and dielectric 132 can be used as a normal reflector 101. The metal reflector 102 may be fixed to the surface of the dielectric 132 of the normal reflector 101 by bonding or the like. The region with a three-layer structure of conductor 131, dielectric 132, and metal reflector 102 can become an asymmetric reflection region AS that forms a metasurface. The region with a two-layer structure of conductor 131 and dielectric 132 without the metal reflector 102 can become a symmetric reflection region SY that gives normal reflection.

[0071] When panels 13A to 13D in Figures 6A to 6D are supported by any of frames 11A to 11D, the conductor 131 is electrically connected by contacting the conductive portion 115 of the frame body 111 to 111D, and the reflected potential is transmitted to the adjacent panel 13.

[0072] Figure 7 shows an example of the treatment of the conductor 131 at the edge of panel 13. Although Figure 7 uses the configuration of panel 13C in Figure 6C, the treatment is also applicable to panel 13B in Figure 6B and panel 13D in Figure 6D. The conductor 131 may be extended outward beyond the edge of the dielectric 132 and folded back at the edge of panel 13 to cover a portion of the surface of at least one of the dielectrics 132. When the edge of panel 13 is inserted into the recess 113 of the frame body 111 of frame 11, the folded portion 131a of the conductor 131 makes surface contact with the conductive portion 115 of the recess 113. In particular, in the case of frames 11A, 11B, and 11D, since no oxide film 112 is formed on the inner surface of the inner portion 113B, the folded portion 131a makes surface contact not only with the conductive portion 115 but also with the inner surface of the inner portion 113B parallel to the XZ plane. By bringing the conductor 131 to the surface of the panel 13 at the folded portion 131a, the contact area between the conductor 131 and the recess 113 is increased, and the electrical connection becomes more stable.

[0073] Figure 8 shows an electromagnetic wave reflector 10A as a modified example of the electromagnetic wave reflector 10. The electromagnetic wave reflector 10A has a metal reflector 102 that is movable on the panel 13. The metal reflector 102 may be integrated with the normal reflector 101 and incorporated into the panel 13D as shown in Figure 6D, or it may be configured to be movable on the reflective surface 105 as shown in Figure 8.

[0074] The configuration for making the position of the metal reflector 102 on the reflective surface 105 variable can be any configuration as long as interference between the metal reflector 102 and the reflective surface 105 is suppressed. For example, a rod 16 that holds the metal reflector 102 may be mounted on the panel 13 so as to be slidable in the horizontal direction, and the position of the metal reflector 102 may be held on the rod 16 so as to be movable in the vertical direction.

[0075] The rod 16 may be made of a non-metallic, low-dielectric material that does not interfere with the reflective properties of the normal reflector 101 or the metal reflector 102. The rod 16 may be designed so that optical and mechanical interference at the panel interface is zero or minimal. The metal reflector 102 can be moved to an optimal position on the panel 13 depending on the environment of the site where the electromagnetic wave reflector 10A is placed, its position relative to the base station BS, etc. The frame 11 has a recess 113 and a hollow portion 114, as in Figures 5A to 5D, and can transmit the reference potential of the reflection phenomenon that occurred on the reflective surface 105 to the reflective surface of the adjacent panel 13.

[0076] Figure 9A shows an electromagnetic wave reflector 10B as another modified example of the electromagnetic wave reflector 10. The electromagnetic wave reflector 10B is freestanding. The electromagnetic wave reflector 10B has a panel 13 having a reflective surface 105 and a frame 12 that supports the panel 13.

[0077] The frame 12 has a base 122 and pillars 121 extending vertically from the base 122. The cross-sectional shape of the pillar 121 when cut by a plane parallel to the X-Y plane is the same as that of frames 11A to 11D shown in Figures 5A to 5D. The pillar 121 is composed of a frame body 111 having a recess 113 and a hollow portion 114.

[0078] In the electromagnetic wave reflector 10B, the panel 13 and frame 12 are separable and can be assembled at the installation site. During assembly, the end of the panel 13 is inserted into the recess 113 of the frame 12 and erected on the installation surface. Since the electromagnetic wave reflector 10B is self-supporting, it can be placed in any desired location indoors or outdoors and can be used as a partition, fence, etc., with radio wave reflecting function.

[0079] In the case of a self-supporting electromagnetic wave reflector 10B as shown in Figure 9A, a brace may be provided on the side of the panel 13 opposite to the reflective surface 105 to reinforce the strength of the panel 13. The brace may be placed diagonally between the frames 12 that hold both ends of the panel 13. Alternatively, a reinforcing beam may be provided at the upper or lower end of the panel 13.

[0080] Figure 9B shows an electromagnetic wave reflector 10C as yet another modification of the electromagnetic wave reflector 10. The electromagnetic wave reflector 10C is freestanding, similar to Figure 9A, and the frame 12 has a base 122 and pillars 121 extending from the base 122. The pillars 121 are made up of a frame body 111 that grips the ends of the panel 13.

[0081] A metal reflector 102 is movably mounted on the panel 13. The movable structure of the metal reflector 102 can be any configuration as long as it does not come into contact with the reflective surface 105. Here, as in Figure 8, a rod 16 that is movable in the horizontal direction indicated by the double arrow is used on the panel 13, and the metal reflector 102 is attached to the rod 16 so as to be movable in the vertical direction (Z direction). By selecting the position of the metal reflector 102 on the panel 13 according to the surrounding environment, the position of the asymmetric reflection region AS (see Figure 6D) can be adjusted.

[0082] Figure 9C shows an electromagnetic wave reflective fence 100A, which is a modified example of the electromagnetic wave reflective fence. The electromagnetic wave reflective fence 100A has a configuration in which a plurality of electromagnetic wave reflecting devices 10B are connected, and panels 13-1 and 13-2 are connected by a frame 12. The frame 12, with a base 122, erects panels 13-1 and 13-2 almost vertically from the X-Y line. The frame body 111 of the pillar 121 grips the ends of panels 13-1 and 13-2, and connects the potential surface of the reflection occurring at the reflective surface 105 of panel 13-1 with the potential surface of the reflection occurring at the reflective surface 105 of panel 13-2. Instead of the electromagnetic wave reflecting devices 10B, the electromagnetic wave reflective fence may be formed by connecting the electromagnetic wave reflecting devices 10C shown in Figure 9B. In either case, the panels 13 and the frame 12 can be transported separately and the fence can be assembled at the installation site. If an electromagnetic wave reflector 10C is used, the position of the metal reflector 102 may be determined during or after the assembly of the electromagnetic wave reflecting fence.

[0083] Even in the configuration shown in Figure 9C, reinforcing braces, reinforcing beams, etc., may be provided on one or both of panels 13-1 and 13-2. By making multiple consecutive panels self-supporting, they can be used as partitions for event venues, protective fences for production lines, etc.

[0084] <Evaluation of Electromagnetic Wave Reflector 10> As part of the evaluation of the electromagnetic wave reflector 10, the reflection characteristics of the frame 11, the durability of the frame 11, and the strength of the electromagnetic wave reflector 10 were evaluated.

[0085] <Evaluation of the Reflectivity of Frame 11> Here, the reflectivity of frame 11 is evaluated. The reflectivity is evaluated by the peak ratio of the scattering cross-section. The peak ratio is expressed as the ratio of the peak intensity of the scattering cross-section in the electromagnetic wave reflector 10, which includes two panels 13-1 and 13-2 supported by frame 11, to the peak intensity of the scattering cross-section in an electromagnetic wave reflector composed of a single panel 13 without using frame 11. The electromagnetic wave reflector 10, which includes two panels 13-1 and 13-2 supported by frame 11, has lower reflectivity compared to an electromagnetic wave reflector composed of a single panel 13, due to the reflection that occurs at frame 11.

[0086] Figure 10 illustrates an example of a method for evaluating reflection characteristics. Figure 10 shows an example of the scattering cross-section when the incident angle of radio waves on the electromagnetic wave reflector 10 is 10 degrees and the waves are reflected in the -10 degree direction by specular reflection.

[0087] The ability to reflect incident electromagnetic waves is evaluated by the radar cross section (RCS), or scattering cross section. The unit of RCS is decibels per square meter (dBsm). By electrically connecting the two panels 13-1 and 13-2 with the frame 11, the main peak intensity of the RCS is reduced compared to an electromagnetic wave reflector consisting of a single panel 13. The peak ratio is the ratio of the main peak intensity of the RCS of the electromagnetic wave reflector 10 (indicated as "connected" in the figure) including the two panels 13-1 and 13-2 supported by the frame 11 to the main peak intensity of the RCS of an electromagnetic wave reflector consisting of a single panel 13 (indicated as "unconnected" in the figure). A higher peak ratio indicates less reduction in peak intensity and better reflection characteristics. A peak ratio of 0.8 or higher is preferable. In the evaluation, general-purpose 3D electromagnetic field simulation software is used to reflect a plane wave of a predetermined frequency off the panel surface and analyze the scattering cross-section.

[0088] Figures 11 and 12 illustrate the analysis space for the reflection characteristics of the embodiments and comparative examples described below. In Figures 11 and 12, as in Figures 5A to 5D, the width direction of the panel 13 is the X direction, the thickness direction is the Y direction, and the height direction is the Z direction, and the analysis space is represented as (size in the X direction) × (size in the Y direction) × (size in the Z direction). When the frequency is 4.8 GHz, the size of the analysis space is 500 mm × 150 mm × 500 mm. As shown in Figure 12, the boundary conditions are designed with electromagnetic wave absorbers placed around the analysis space.

[0089] In evaluating the reflection characteristics of frame 11, a simulation model of frame 11D shown in Figure 5D was used as an example. The frame body 111 of frame 11D was positioned so that the center of the surface on the +Y direction side (surface of the oxide film 112) in the X direction was located on the Z axis in the analysis space shown in Figures 11 and 12, and the reflection characteristics were determined by setting the incidence angle of radio waves to 0°, 10°, 20°, and 30°.

[0090] In the actual panel 13, a conductive mesh may be used as the conductor 131, with its ends folded back as shown in Figure 7. However, in the simulation model, a simple configuration is used in which the conductor 131 is sandwiched between two dielectrics 132. A 2.5 mm thick polycarbonate is used as the dielectric 132, and SUS is used as the conductor 131 between the two polycarbonates. The total thickness of the panel 13 is 5.0 mm.

[0091] <Evaluation of the durability of frame 11 and the strength of electromagnetic wave reflector 10> For the evaluation of the durability of frame 11, a salt spray test was conducted. Specifically, the relative ratio of the resistance value after the test to the resistance value before the test, which conforms to the salt spray test of JIS Z 2371, was evaluated.

[0092] The salt spray test in accordance with JIS Z 2371 was conducted using a frame 11 with a height of 300 mm, following the test specimen in JIS Z 2371:215, section 7.2, and the test was performed on the frame 11 alone.

[0093] The salt spray test in accordance with JIS Z 2371 was conducted using the apparatus described in Annex A of JIS Z 2371:215, following the test conditions described in the 9 test conditions of JIS Z 2371:215.

[0094] <Evaluation of the strength of the electromagnetic wave reflector 10> The electromagnetic wave reflector 10 in Examples 1 to 6 below was tested in accordance with the pendulum test of ISO 14120.

[0095] The pendulum test in ISO 14120 is the pendulum test shown in Figure C.1 of ISO 14120:2015, and is equivalent to the pendulum test shown in Figure C.1 of JIS B 9716:2019. Therefore, a test conforming to the ISO 14120 pendulum test is, more specifically, a test conforming to the pendulum test shown in Figure C.1 of ISO 14120:2015, and a test conforming to the pendulum test shown in Figure C.1 of JIS B 9716:2019.

[0096] The pendulum test shown in Figure C. 1 of ISO 14120:2015 and JIS B 9716:2019 is a test that can be used to test the resistance of a guard to impacts from outside and inside a protected hazardous area. This guard corresponds to the electromagnetic wave reflector 10 in this disclosure.

[0097] The pendulum test shown in Figure C.1 of ISO 14120:2015 and JIS B 9716:2019 involves connecting three electromagnetic wave reflectors 10 in the width direction (X direction in Figure 2) and having a pendulum collide with the central electromagnetic wave reflector 10.

[0098] In Figure C.1 of ISO 14120:2015 and JIS B 9716:2019, the height H is the height H of the electromagnetic wave reflector 10, and as an example, it was set to 2000 mm.

[0099] In Figure C. 1 of ISO 14120:2015 and JIS B 9716:2019, the downward swing height h is a position that is h higher than the height H, and is set to 140 mm as an example.

[0100] In Figure C. 1 of ISO 14120:2015 and JIS B 9716:2019, the height 'a' at which the impact is applied is the height at which the pendulum collides with the central electromagnetic wave reflector 10 of the three panels, and was set to 1333 mm as an example.

[0101] In accordance with ISO 14120 pendulum testing, three electromagnetic wave reflectors 10 were connected in the width direction, and a pendulum was struck against the central electromagnetic wave reflector 10 of the three with an energy of E = 115 J or more.

[0102] Under these conditions, a test was conducted in accordance with the pendulum test shown in Figure C. 1 of ISO 14120:2015 and JIS B 9716:2019, and measurement results were obtained for two items: (1) whether the pendulum penetrates the central electromagnetic wave reflector 10, and (2) whether the panel 13 of any of the three electromagnetic wave reflectors 10 is detached from the frame 11A. The energy of the pendulum in the test should be 115 J or more, but as an example, a maximum of 2000 J is sufficient. Therefore, the energy of the pendulum in the test should be between 115 J and 2000 J.

[0103] Hereinafter, a test conforming to the pendulum test shown in Figure C. 1 of ISO 14120:2015 and JIS B 9716:2019 will be referred to as a test conforming to the ISO 14120 pendulum test. Having strength conforming to the ISO 14120 pendulum test means that it meets the conditions of two items (1) and (2) in the test conforming to the pendulum test shown in Figure C. 1 of ISO 14120:2015 and JIS B 9716:2019.

[0104] <Example 1> Example 1 is Embodiment 1. The panel 13 has a thickness of 5.0 mm in the Y direction, and the frame body 111 is made of aluminum with a thickness of 19.5 mm in the Y direction and a width of 55.0 mm in the X direction. The frame 11 is manufactured by extrusion, and then an anodized film is formed on the outer surface 116 as an oxide film 112. The anodized film is not formed inside the recesses 113 of the panel 13. That is, the frame 11D shown in Figure 5D was used as the frame 11. All corners (edges) of the frame 11 are chamfered with an R chamfer, and the minimum value of the radius of curvature R is 0.1 mm.

[0105] With panel 13 inserted into the recess 113 of frame 11 and the conductor 131 in contact with the conductive portion 115, simulations were performed when incident light was applied at a frequency of 4.8 GHz and incident angles from 0° to 30° in 10° increments. The intensity ratio of the main peak of the scattering cross-section was 0.89 at an incident angle of 0°, 0.96 at 10°, 1.08 at 20°, and 0.97 at 30°, with an average value of 0.98.

[0106] A salt spray test was performed on frame 11 in accordance with JIS Z 2371. When the relative ratio of the resistance value after the test to the resistance value before the test was determined, the resistance value of the surface of frame 11 (anodized film surface) before the test was set to 1.00, and the resistance value of the surface inside recess 113 after the test was 10.0. The resistance value increased because the inside of recess 113 is not covered with an anodized film, but it was confirmed that the two adjacent panels 13 were not non-conductive to each other as they were supported by frame 11.

[0107] Two panels 13 were inserted into a frame 11 having pillars 121 and bases 122 to assemble the electromagnetic wave reflective fence 100A of Example 1, which has the configuration shown in Figure 9C. The electromagnetic wave reflective fence 100A of Example 1 was subjected to a test in accordance with the pendulum test of ISO 14120, and when the test was performed at E = 134J, the panels 13 and frame 11 did not come apart, and no damage occurred anywhere. Therefore, it was confirmed that the electromagnetic wave reflective fence 100A of Example 1 passed the test in accordance with the pendulum test of ISO 14120.

[0108] <Example 2> Example 2 is Embodiment 2. The panel 13 has a thickness of 5.0 mm in the Y direction, and the frame body 111 is made of aluminum with a thickness of 10.0 mm in the Y direction and a width of 35.0 mm in the X direction. The frame 11 is manufactured by extrusion, and then an anodized film is formed on the outer surface 116 as an oxide film 112. The anodized film is not formed inside the recesses 113 of the panel 13. That is, the frame 11D shown in Figure 5D was used as the frame 11. All corners (edges) of the frame 11 are chamfered with an R chamfer, and the minimum value of the radius of curvature R is 0.5 mm.

[0109] With panel 13 inserted into the recess 113 of frame 11 and the conductor 131 in contact with the conductive portion 115, simulations were performed when incident light was applied at a frequency of 4.8 GHz and at incident angles from 0° to 30° in 10° increments. The intensity ratio of the main peak of the scattering cross-section was 0.88 at an incident angle of 0°, 0.95 at 10°, 1.05 at 20°, and 0.98 at 30°, with an average value of 0.97.

[0110] A salt spray test was performed on frame 11 in accordance with JIS Z 2371. When the relative ratio of the resistance value after the test to the resistance value before the test was determined, the resistance value of the surface of frame 11 (anodized film surface) before the test was set to 1.00, and the resistance value of the surface inside recess 113 after the test was 15.0. The resistance value increased because the inside of recess 113 is not covered with an anodized film, but it was confirmed that the two adjacent panels 13 were not non-conductive to each other because they were supported by frame 11.

[0111] Two panels 13 were inserted into a frame 11 having pillars 121 and bases 122 to assemble the electromagnetic wave reflective fence 100A of Example 2, which has the configuration shown in Figure 9C. The electromagnetic wave reflective fence 100A of Example 2 was tested in accordance with the pendulum test of ISO 14120, and when tested at E = 115J, the panels 13 and frame 11 did not detach, and no damage occurred anywhere. Therefore, it was confirmed that the electromagnetic wave reflective fence 100A of Example 2 passes the test in accordance with the pendulum test of ISO 14120.

[0112] <Example 3> Example 3 is Embodiment 3. The panel 13 has a thickness of 5.0 mm in the Y direction, and the frame body 111 is made of aluminum with a thickness of 25.0 mm in the Y direction and a width of 70.0 mm in the X direction. The frame 11 is manufactured by extrusion, and then an anodized film is formed on the outer surface 116 as an oxide film 112. The anodized film is not formed inside the recesses 113 of the panel 13. That is, the frame 11D shown in Figure 5D was used as the frame 11. All corners (edges) of the frame 11 are chamfered with an R chamfer, and the minimum value of the radius of curvature R is 0.3 mm.

[0113] With panel 13 inserted all the way into the recess 113 of frame 11 and the conductor 131 in contact with the conductive portion 115, simulations were performed when incident light was applied at a frequency of 4.8 GHz and at incident angles from 0° to 30° in 10° increments. The intensity ratio of the main peak of the scattering cross-section was 0.80 at an incident angle of 0°, 0.82 at 10°, 0.80 at 20°, and 0.85 at 30°, with an average value of 0.82.

[0114] A salt spray test was performed on frame 11 in accordance with JIS Z 2371. When the relative ratio of the resistance value after the test to the resistance value before the test was determined, the resistance value of the surface of frame 11 (anodized film surface) before the test was set to 1.00, and the resistance value of the surface of frame 11 (anodized film surface) after the test was 1.00, while the resistance value of the inside surface of recess 113 after the test was 1000.0. The resistance value increased because the inside of recess 113 is not covered with an anodized film, but it was confirmed that the two adjacent panels 13 were not non-conductive to each other as they were supported by frame 11.

[0115] Two panels 13 were inserted into a frame 11 having pillars 121 and bases 122 to assemble the electromagnetic wave reflective fence 100A of Example 3, which has the configuration shown in Figure 9C. The electromagnetic wave reflective fence 100A of Example 3 was tested in accordance with the pendulum test of ISO 14120, and when tested at E = 115J, the panels 13 and frame 11 did not detach, and no damage occurred anywhere. Therefore, it was confirmed that the electromagnetic wave reflective fence 100A of Example 3 passes the test in accordance with the pendulum test of ISO 14120.

[0116] <Example 4> Example 4 is Embodiment 4. The panel 13 has a thickness of 5.0 mm in the Y direction, and the frame body 111 is made of aluminum with a thickness of 22.5 mm in the Y direction and a width of 55.0 mm in the X direction. The frame 11 is manufactured by extrusion, and then an anodized film is formed on the outer surface 116 as an oxide film 112. The anodized film is not formed inside the recesses 113 of the panel 13. That is, the frame 11D shown in Figure 5D was used as the frame 11. All corners (edges) of the frame 11 are chamfered with an R chamfer, and the minimum value of the radius of curvature R is 0.3 mm.

[0117] With panel 13 inserted all the way into the recess 113 of frame 11 and the conductor 131 in contact with the conductive portion 115, simulations were performed when incident light was applied at a frequency of 4.8 GHz and at incident angles from 0° to 30° in 10° increments. The intensity ratio of the main peak of the scattering cross-section was 0.81 at an incident angle of 0°, 0.82 at 10°, 0.80 at 20°, and 0.81 at 30°, with an average value of 0.81.

[0118] A salt spray test was performed on frame 11 in accordance with JIS Z 2371. When the relative ratio of the resistance value after the test to the resistance value before the test was determined, the resistance value of the surface of frame 11 (anodized film surface) before the test was set to 1.00, and the resistance value of the surface inside the recess 113 after the test was 1.00. The resistance value of the inside of the recess 113 after the test was 25.0. The resistance value increased because the inside of the recess 113 is not covered with an anodized film, but it was confirmed that the two adjacent panels 13 were not non-conductive to each other because they were supported by frame 11.

[0119] Two panels 13 were inserted into a frame 11 having pillars 121 and bases 122 to assemble the electromagnetic wave reflective fence 100A of Example 4, which has the configuration shown in Figure 9C. The electromagnetic wave reflective fence 100A of Example 4 was tested in accordance with the pendulum test of ISO 14120, and when tested at E = 125J, the panels 13 and frame 11 did not detach, and no damage occurred anywhere. Therefore, it was confirmed that the electromagnetic wave reflective fence 100A of Example 4 passes the test in accordance with the pendulum test of ISO 14120.

[0120] <Example 5> Example 5 is Comparative Example 1. The panel 13 has a thickness of 5.0 mm in the Y direction, and the frame body 111 is made of aluminum with a thickness of 30.5 mm in the Y direction and a width of 75.0 mm in the X direction. The frame 11 was manufactured by extrusion. In Example 5, no oxide film 112 (anodized film) is formed on the frame 11. That is, in Example 5, no oxide film 112 (anodized film) is formed on any of the surfaces of the frame 11 (outer surface 116, inner surface of recess 113, and inner surface of hollow portion 114). All corners (edges) of the frame 11 are chamfered with an R chamfer, and the minimum value of the radius of curvature R is 0.3 mm.

[0121] With panel 13 inserted into the recess 113 of frame 11 and the conductor 131 in contact with the conductive portion 115, simulations were performed when incident light was applied at a frequency of 4.8 GHz and at incident angles from 0° to 30° in 10° increments. The intensity ratio of the main peak of the scattering cross-section was 0.70 at an incident angle of 0°, 0.25 at 10°, 0.70 at 20°, and 0.55 at 30°, with an average value of 0.55.

[0122] A salt spray test was performed on frame 11 in accordance with JIS Z 2371. The relative ratio of the resistance value after the test to the resistance value before the test was calculated. When the resistance value of the surface of frame 11 (surface of the aluminum member) before the test was set to 1.00, the resistance value of the surface of frame 11 (surface of the aluminum member) after the test was 1000.0. The resistance value increased because frame 11 is not coated with an anodized film, but it was confirmed that the two adjacent panels 13 were supported by frame 11 and did not become non-conductive.

[0123] Two panels 13 were inserted into a frame 11 having pillars 121 and bases 122 to assemble the electromagnetic wave reflective fence 100A of Example 5, which has the configuration shown in Figure 9C. The electromagnetic wave reflective fence 100A of Example 5 was subjected to a test in accordance with the pendulum test of ISO 14120, and when the test was performed at E = 115J, the panels 13 and frame 11 did not come apart, and no damage occurred anywhere. Therefore, it was confirmed that the electromagnetic wave reflective fence 100A of Example 5 passes the test in accordance with the pendulum test of ISO 14120.

[0124] <Example 6> Example 6 is Comparative Example 2. The panel 13 has a thickness of 5.0 mm in the Y direction, and the frame body 111 is made of aluminum with a thickness of 22.5 mm in the Y direction and a width of 55.0 mm in the X direction. No anodized coating is formed on the outer surface 116 of the frame 11. Furthermore, no anodized coating is formed inside the recess 113 of the panel 13. All corners (edges) of the frame 11 are chamfered with a radius of curvature R of 0.3 mm.

[0125] With the panel 13 inserted all the way into the recess 113 of the frame 11 and the conductor 131 in contact with the conductive portion 115, simulations were performed when the incident light was incident at a frequency of 4.8 GHz and at incident angles from 0° to 30° in 10° increments. The intensity ratio of the main peak of the scattering cross-section was 0.81 at an incident angle of 0°, 0.81 at 10°, 0.80 at 20°, and 0.84 at 30°, with an average value of 0.82.

[0126] Frame 11 was tested in accordance with the salt spray test of JIS Z 2371. When the relative ratio of the resistance value after the test to the resistance value before the test was determined, the resistance value of the surface of frame 11 (anodized coating surface) before the test was set to 1.00, and the resistance value of the surface inside the recess 113 after the test was 0.00 (overload).

[0127] In Example 6, however, a test in accordance with the ISO 14120 pendulum test was not performed.

[0128] <Effects> The electromagnetic wave reflecting device 10 of this disclosure includes a panel 13 having a reflective surface that reflects radio waves in a desired frequency band selected from the frequency band of 1 MHz to 300 GHz, and a support (frame 11) made of a conductive material that supports the panel 13. The support (frame 11) has a conductive portion 115 that is electrically connected to the panel 13, and an insulating film (oxide film 112) formed on at least a portion of the portion other than the conductive portion 115. As a result, at least a portion of the surface of the frame 11 is covered with the insulating film (oxide film 112), and the electrical characteristics of the frame 11 are maintained in good condition for a long period of time even when exposed to wind and rain. Furthermore, by installing the electromagnetic wave reflecting device 10, NLOS spots are reduced and the radio wave propagation environment is improved.

[0129] Therefore, we can provide an electromagnetic wave reflector 10 that achieves both improved radio wave propagation environment and improved weather resistance.

[0130] Furthermore, the conductive material of the support (frame 11) is composed of a metal with an electrical conductivity of 30.0 IACS% or higher, and the insulating film (oxide film 112) may be a metal oxide film with a thickness of 1.0 μm to 50.0 μm. By covering the frame 11, which is made of a conductive material with high electrical conductivity, with an oxide film of sufficient thickness, the electrical properties of the frame 11 are maintained in good condition for a long period of time even when exposed to wind and rain. Therefore, an electromagnetic wave reflector 10 with high electrical reliability can be provided.

[0131] Furthermore, the metal is aluminum, and the oxide film 112 may be an anodized film. The oxide film 112 can be easily formed by performing an oxidation treatment on the surface of the aluminum frame 11. In addition, the oxide film 112 can cover the aluminum frame body for a long period of time. Therefore, it is possible to provide an electromagnetic wave reflector 10 that is highly durable and electrically reliable over a long period of time.

[0132] Furthermore, the support (frame 11) may have a relative ratio of its resistance value after testing to its resistance value before testing in accordance with the salt spray test of JIS Z 2371, which is between 1.00 and 1000.00. This allows for the provision of an electromagnetic wave reflector 10 that is highly durable and electrically reliable over a long period of time.

[0133] Furthermore, the support (frame 11) is a frame that supports the panel 13, the thickness of the frame 11 is greater than the thickness of the panel 13, the frame 11 has a recess into which the end of the panel 13 is inserted, the conductive portion 115 of the frame 11 is located inside the recess, the difference between the thickness of the frame 11 and the thickness of the panel 13 is 5.0 mm or more and 20.0 mm or less, the width of the frame 11 is 35.0 mm or more and 70.0 mm or less, and at least a part of the corners of the frame 11 is rounded, and may have a radius of curvature of 0.1 mm or more and 3.0 mm or less. By having the frame 11 and the panel 13 have the above sizes, a structurally stable electromagnetic wave reflecting device 10 can be provided. In addition, by rounding the corners of the frame 11, abnormal scattering at the corners can be suppressed.

[0134] Furthermore, the electromagnetic wave reflector 10 may have the strength to withstand tests compliant with the ISO 14120 pendulum test, which involves impacting a pendulum with an energy of E = 115 J or more. Therefore, the electromagnetic wave reflector 10 can ensure sufficient strength for safety measures. Thus, it is possible to provide an electromagnetic wave reflector 10 that achieves improvements in the radio wave propagation environment, improved weather resistance, and ensures sufficient strength for the electromagnetic wave reflector.

[0135] Furthermore, the ratio of the main peak intensity of the scattering cross-sectional area of ​​the electromagnetic wave reflector 10, which includes two panels 13-1 and 13-2 supported by the frame 11, to the main peak intensity of the scattering cross-sectional area of ​​an electromagnetic wave reflector composed of a single panel 13 without using the frame 11, may be 0.8 or more. As a result, the electromagnetic wave reflector 10 has good reflection characteristics. Therefore, it is possible to provide an electromagnetic wave reflector 10 that achieves both an improvement in the radio wave propagation environment due to good reflection characteristics and an improvement in weather resistance.

[0136] Furthermore, the reflective surface of the panel 13 may be a reflective surface that performs specular reflection, a reflective surface that performs non-specular reflection, or a reflective surface having a region that performs specular reflection and a region that performs non-specular reflection. By using specular reflection, non-specular reflection, or both specular and non-specular reflection, it is possible to provide an electromagnetic wave reflecting device 10 that can reflect radio waves at a desired angle, thereby achieving both improved radio wave propagation environment and improved weather resistance.

[0137] Furthermore, the support (frame 11) may have a base 122 provided at its lower end, and may be able to support the panel 13 and stand upright relative to the installation surface. Since the panel 13 can be made self-supporting, an electromagnetic wave reflector 10 that can be easily installed in various locations can be provided.

[0138] The electromagnetic wave reflective fence 100 of this disclosure has a configuration in which a plurality of electromagnetic wave reflective devices 10 described in any one of the above items are connected by a support (frame 11). Therefore, at least a part of the surface of the frame 11 is covered with an insulating film (oxide film 112), so that the electrical characteristics of the frame 11 are maintained in good condition for a long period of time even when exposed to wind and rain. In addition, by installing the electromagnetic wave reflective devices 10, NLOS spots are reduced and the radio wave propagation environment is improved.

[0139] Therefore, we can provide an electromagnetic wave reflective fence 100 that achieves both improved radio wave propagation environment and improved weather resistance.

[0140] The assembly method for the electromagnetic wave reflecting device 10 of this disclosure includes a first panel (panel 13-1) having a first reflective surface that reflects radio waves in a desired band selected from the frequency band of 1 MHz to 300 GHz, a second panel (panel 13-2) having a second reflective surface that reflects radio waves in the band, and a support (frame 11) made of a conductive material that supports the first panel (panel 13-1) and the second panel (panel 13-2), wherein the support (frame 11) has a conductive portion 115 that is electrically connected to the first panel (panel 13-1) and the second panel (panel 13-2), and a conductive portion A method for assembling an electromagnetic wave reflector 10, which has an insulating coating (oxide film 112) formed on at least a portion of the part other than 115, wherein a first panel (panel 13-1) and a second panel (panel 13-2) are supported on a support (frame 11), the first panel (panel 13-1) and the second panel (panel 13-2) are connected to the conductive portion 115, and the first panel (panel 13-1) and the second panel (panel 13-2) are mechanically connected by the support (frame 11), and the reference potential for reflection is made continuous between the first reflective surface and the second reflective surface. As a result, at least a portion of the surface of the frame 11 is covered with an insulating coating (oxide film 112), and the electrical characteristics of the frame 11 are kept in good condition for a long period of time even when exposed to wind and rain. Furthermore, by installing the electromagnetic wave reflector 10, NLOS spots are reduced and the radio wave propagation environment is improved.

[0141] Therefore, it is possible to provide an assembly method for an electromagnetic wave reflector 10 that achieves both improved radio wave propagation environment and improved weather resistance.

[0142] While exemplary electromagnetic wave reflectors, electromagnetic wave reflecting fences, and wireless transmission systems of this disclosure have been described above, this disclosure is not limited to the specifically disclosed embodiments, and various modifications and changes are possible without departing from the scope of the claims.

[0143] The following additional notes are disclosed with respect to the above embodiments. (Note 1) An electromagnetic wave reflecting device comprising: a panel having a reflective surface that reflects radio waves in a desired frequency band selected from the frequency band of 1 MHz to 300 GHz; and a support made of a conductive material that supports the panel, wherein the support has a conductive portion that is in electrical contact with the panel; and an insulating film formed on at least a portion of the portion other than the conductive portion. (Note 2) The electromagnetic wave reflecting device according to Note 1, wherein the conductive material of the support is composed of a metal with an electrical conductivity of 30.0 IACS% or more; and the insulating film is an oxide film of the metal with a thickness of 1.0 μm or more and 50.0 μm or less. (Note 3) The electromagnetic wave reflecting device according to Note 2, wherein the metal is aluminum and the oxide film is an anodized film. (Note 4) The electromagnetic wave reflecting device according to any one of Notes 1 to 3, wherein the support body has a relative ratio of the resistance value after performing a test to the resistance value before performing a test in accordance with the salt spray test of JIS Z 2371, which is 1.00 or more and 1000.00 or less. (Note 5) The electromagnetic wave reflecting device according to any one of Notes 1 to 4, wherein the support body is a frame that supports the panel, the thickness of the frame is greater than the thickness of the panel, the frame has a recess into which the end of the panel is inserted, the conductive portion of the frame is located inside the recess, the difference between the thickness of the frame and the thickness of the panel is 5.0 mm or more and 20.0 mm or less, the width of the frame is 35.0 mm or more and 70.0 mm or less, and at least a part of the corners of the frame is rounded and has a radius of curvature of 0.1 mm or more and 3.0 mm or less. (Note 6) An electromagnetic wave reflector according to any one of Notes 1 to 5, having strength suitable for a test conforming to the pendulum test of ISO 14120, in which a pendulum is struck with an energy of E = 115 J or more. (Note 7) An electromagnetic wave reflector according to any one of Notes 1 to 6, wherein the ratio of the main peak intensity of the scattering cross-section of an electromagnetic wave reflector consisting of one panel without using the support to the main peak intensity of the scattering cross-section of an electromagnetic wave reflector including two panels supported by the support is 0.8 or more.(Note 8) The electromagnetic wave reflecting device according to any one of Notes 1 to 7, wherein the reflective surface of the panel is a reflective surface that performs specular reflection, a reflective surface that performs non-specular reflection, or a reflective surface having a region that performs specular reflection and a region that performs non-specular reflection. (Note 9) The electromagnetic wave reflecting device according to any one of Notes 1 to 8, wherein the support has a base provided at its lower end and is able to support the panel and stand upright relative to the installation surface. (Note 10) An electromagnetic wave reflecting fence in which a plurality of electromagnetic wave reflecting devices according to any one of Notes 1 to 9 are connected by the support. (Note 11) A method for assembling an electromagnetic wave reflector comprising: a first panel having a first reflective surface that reflects radio waves in a desired frequency band selected from the frequency band of 1 MHz to 300 GHz; a second panel having a second reflective surface that reflects radio waves in the said frequency band; and a support made of a conductive material that supports the first panel and the second panel, wherein the support has a conductive portion that is in electrical contact with the first panel and the second panel, and an insulating film formed on at least a portion of the portion other than the conductive portion, wherein the first panel and the second panel are supported by the support, the first panel and the second panel are made electrical to the conductive portion, the first panel and the second panel are mechanically connected by the support, and a reference potential for reflection is maintained between the first reflective surface and the second reflective surface.

[0144] This application claims priority based on Japanese Patent Application No. 2024-158546, filed on 12 September 2024, and incorporates all of its disclosures herein.

[0145] 10, 10A-10C Electromagnetic wave reflector 100, 100A Electromagnetic wave reflecting fence 11, 11A, 11B, 11C, 11D, 12 Frame (example of support) 111 Frame body 112 Oxide film 113 Recess 114 Hollow part 115 Conductive part 116 Outer surface 121 Pillar 122 Base 13, 13-1, 13-2 Panel 16 Rod 101 Normal reflector 102 Metal reflector 105 Reflective surface 131 Conductor 132 Dielectric

Claims

1. An electromagnetic wave reflecting device comprising: a panel having a reflective surface that reflects radio waves in a desired frequency band selected from the frequency band of 1 MHz to 300 GHz; and a support made of a conductive material that supports the panel, wherein the support has a conductive portion that is in electrical contact with the panel, and an insulating coating formed on at least a portion of the portion other than the conductive portion.

2. The electromagnetic wave reflecting device according to claim 1, wherein the conductive material of the support is composed of a metal with an electrical conductivity of 30.0 IACS% or more, and the insulating film is an oxide film of the metal with a thickness of 1.0 μm or more and 50.0 μm or less.

3. The electromagnetic wave reflecting device according to claim 2, wherein the metal is aluminum and the oxide film is an anodized film.

4. The electromagnetic wave reflecting device according to any one of claims 1 to 3, wherein the support has a relative ratio of the resistance value after performing a test to the resistance value before performing a test in accordance with the salt spray test of JIS Z 2371, which is 1.00 or more and 1000.00 or less.

5. The electromagnetic wave reflecting device according to any one of claims 1 to 3, wherein the support is a frame that supports the panel, the thickness of the frame is greater than the thickness of the panel, the frame has a recess into which the end of the panel is inserted, the conductive portion of the frame is located inside the recess, the difference between the thickness of the frame and the thickness of the panel is 5.0 mm or more and 20.0 mm or less, the width of the frame is 35.0 mm or more and 70.0 mm or less, and at least a portion of the corners of the frame is rounded and has a radius of curvature of 0.1 mm or more and 3.0 mm or less.

6. An electromagnetic wave reflector according to any one of claims 1 to 3, having strength suitable for a test in accordance with the pendulum test of ISO 14120, in which a pendulum is struck with an energy of E = 115 J or more.

7. The electromagnetic wave reflector according to any one of claims 1 to 3, wherein the ratio of the main peak intensity of the scattering cross-section of an electromagnetic wave reflector comprising two panels supported by the support to the main peak intensity of the scattering cross-section of an electromagnetic wave reflector comprising one panel without using the support is 0.8 or more.

8. The electromagnetic wave reflecting device according to any one of claims 1 to 3, wherein the reflective surface of the panel is a reflective surface that performs specular reflection, a reflective surface that performs non-specular reflection, or a reflective surface having a region that performs specular reflection and a region that performs non-specular reflection.

9. The electromagnetic wave reflecting device according to any one of claims 1 to 3, wherein the support has a base provided at its lower end and is able to support the panel and stand upright relative to the installation surface.

10. An electromagnetic wave reflecting fence comprising a plurality of electromagnetic wave reflecting devices according to any one of claims 1 to 3, connected by a support body.

11. A method for assembling an electromagnetic wave reflector comprising: a first panel having a first reflective surface that reflects radio waves in a desired frequency band selected from the frequency band of 1 MHz to 300 GHz; a second panel having a second reflective surface that reflects radio waves in the said frequency band; and a support made of a conductive material that supports the first panel and the second panel, wherein the support has a conductive portion that is electrically connected to the first panel and the second panel, and an insulating film formed on at least a portion of the portion other than the conductive portion, wherein the first panel and the second panel are supported by the support, the first panel and the second panel are electrically connected to the conductive portion, the first panel and the second panel are mechanically connected by the support, and a reference potential for reflection is maintained between the first reflective surface and the second reflective surface.

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