Electromagnetic wave reflecting device, electromagnetic wave reflecting fence and reflecting panel

Abstract

The present invention suppresses a decrease in reflection efficiency in an electromagnetic wave reflection device having a conductive pattern bonded by an adhesive layer. An electromagnetic wave reflection device is provided with: a reflection panel that reflects an electromagnetic wave in a desired frequency band selected from among frequency bands of 1 GHz to 170 GHz (inclusive); and a frame that holds the reflective panel, the reflective panel having a dielectric layer, a periodic conductive pattern provided on one surface of the dielectric layer, a ground layer provided on the other surface of the dielectric layer, and an adhesive layer that bonds the conductive pattern and the one surface of the dielectric layer. The adhesive layer covers the entire one surface of the dielectric layer, and in the range of 1 GHz to 30 GHz, the adhesive layer has a relative dielectric constant of 2.0 or more but less than 3.0 and a dielectric loss tangent of more than 0.00 but less than 0.10, or the adhesive layer has a relative dielectric constant of 3.0 or more but less than 4.5, and the dielectric loss tangent of more than 0.00 but less than 0.10. And the dielectric loss tangent is greater than 0.00 and 0.02 or less.

Description

Technical Field

[0001] The invention relates to an electromagnetic wave reflecting device, an electromagnetic wave reflecting fence and a reflecting panel. Background Art

[0002] In the fifth generation (hereinafter referred to as "5G") mobile communication standard, high-speed and large-capacity communications are expected. On the other hand, radio waves with strong linear propagation properties are used, so places where radio waves are difficult to reach can be created. In places where there are many metal machines such as in factories, and in places where there are many reflections on walls and roadside trees such as building streets, a mechanism for transmitting radio waves to target terminal devices and wireless devices is required. The same requirement also exists in places where points where base station antennas cannot be seen (NLOS: Non-Line-Of-Sight), such as medical sites, event venues, and large commercial facilities.

[0003] In recent years, reflective surfaces with artificial surfaces called "metasurfaces" are being developed. The metasurface is formed by periodic structures or patterns that are smaller than the wavelength and is designed to reflect radio waves in a desired direction (for example, refer to non-patent document 1). The metasurface itself is realized by periodically repeated tiny structures and metal patterns, but in the case of actual manufacturing, a metal pattern is provided on one surface of a dielectric substrate, and a ground layer is provided on the surface on the opposite side. The metasurface can achieve the desired reflection angle while maintaining the configuration structure of the plane, so it can effectively function as a reflector even in an environment where there is not enough space to set up a large number of electromagnetic wave reflection panels.

[0004] The metal pattern and ground layer are often formed of a good conductive metal such as copper (Cu), nickel (Ni), or silver (Ag). The reflective surface including the metasurface functions through the metal pattern, which requires a precise pattern. The ground layer is formed on one surface of the dielectric substrate by processes such as sputtering and evaporation. The metal pattern can be formed by etching, electroplating, etc.

[0005] Non-patent literature 1: Diaz-Rubio et al., Sci. Adv. 2017: 3: e1602714 1

[0006] It is not easy to directly form a metal pattern on the other side of a dielectric substrate formed with a metal ground layer by engraving a pattern. Therefore, it is considered to join the metal pattern via an adhesive layer. In the reflection surface joined with the metal pattern via an adhesive layer, the dielectric constant of the dielectric substrate and the adhesive layer significantly affects the reflection angle and reflection efficiency. In order to improve the propagation environment, the reflection efficiency is preferably above 60% or above 70%. In particular, if a conventional acrylic adhesive is applied to the entire surface, the reflection efficiency is reduced to less than 60%, making it difficult to fully improve the propagation environment. Summary of the invention

[0007] An object of the present invention is to suppress a decrease in reflection efficiency in an electromagnetic wave reflecting device having a conductive pattern bonded by an adhesive layer.

[0008] In one embodiment, an electromagnetic wave reflecting device comprises: a reflecting panel that reflects radio waves in a desired frequency band selected from a frequency band of 1 GHz to 170 GHz; and a frame that holds the reflecting panel, wherein the reflecting panel comprises: a dielectric layer, a periodic conductive pattern arranged on one surface of the dielectric layer, a ground layer arranged on another surface of the dielectric layer, and an adhesive layer that joins the conductive pattern to the one surface of the dielectric layer, wherein the adhesive layer covers the entire surface of the one surface of the dielectric layer, and within the range of 1 GHz to 30 GHz, the relative dielectric constant is greater than 2.0 and less than 3.0 and the dielectric loss tangent is greater than 0.00 and less than 0.10, or the relative dielectric constant of the adhesive layer is greater than 3.0 and less than 4.5 and the dielectric loss tangent is greater than 0.00 and less than 0.02.

[0009] In an electromagnetic wave reflecting device having a conductive pattern bonded via an adhesive layer, a decrease in reflection efficiency can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a schematic diagram of an electromagnetic wave reflecting fence formed by connecting multiple electromagnetic wave reflecting devices.

[0011] Figure 2 It is along Figure 1 A horizontal cross-section of the frame along line AA.

[0012] Figure 3 It means in Figure 2 The frame is inserted into the diagram of the state of the panel.

[0013] Figure 4A This is a diagram showing an example of the layer structure of the reflection panel.

[0014] Figure 4B It is a diagram showing another example of the layer structure of the reflection panel.

[0015] Figure 5 This is a diagram showing a model of a conductive pattern used for evaluating reflection characteristics.

[0016] Figure 6 Yes means Figure 5 Schematic diagram of the structure of the unit cell of the model.

[0017] Figure 7 is a graph representing the analytical space.

[0018] Fig. 8A This is a schematic diagram of the XY plane of the analytical space.

[0019] Figure 8B It is a schematic diagram of the XZ plane of the analytical space.

[0020] Figure 8C It is a schematic diagram of the YZ plane of the analytical space.

[0021] Fig. 9 This is a graph showing the relationship between the relative dielectric constant and dielectric loss tangent of the adhesive layer at 28 GHz and the power reflection efficiency.

[0022] Fig.10 This is a graph showing the relationship between the relative dielectric constant and dielectric loss tangent of the adhesive layer at 1 GHz and the power reflection efficiency. DETAILED DESCRIPTION

[0023] In order to improve the propagation environment using an electromagnetic wave reflection device, it is expected that the reflection efficiency of the electromagnetic wave reflection device is 60% or more, preferably 70% or more. In an embodiment, in an electromagnetic wave reflection device in which a conductive pattern is bonded to a dielectric layer through an adhesive layer, the dielectric constant and dielectric loss tangent of the dielectric layer are maintained within a specific range, thereby suppressing the reduction in the reflection efficiency of the electromagnetic wave reflection device. In the following description, when it is recorded as "reflection efficiency", it refers to the power reflection efficiency unless otherwise specified. In the figure, the same structural elements are sometimes marked with the same figure mark and repeated descriptions are omitted.

[0024] Figure 1 It is a schematic diagram of an electromagnetic wave reflecting fence 100 formed by connecting electromagnetic wave reflecting devices 60 - 1 , 60 - 2 , and 60 - 3 . Figure 1 In the embodiment, three electromagnetic wave reflecting devices 60-1, 60-2, and 60-3 (hereinafter, sometimes appropriately referred to as "electromagnetic wave reflecting devices 60") are connected to form the electromagnetic wave reflecting fence 100, but the number of the connected electromagnetic wave reflecting devices 60 is not particularly limited.

[0025] The electromagnetic wave reflection device 60-1, 60-2, 60-3 respectively has a reflection panel 10-1, 10-2, 10-3 (hereinafter sometimes appropriately referred to as "reflection panel 10"). The width direction of the reflection panel 10 is taken as the X direction, the height direction is taken as the Y direction, and the thickness direction is taken as the Z direction. Each reflection panel 10 reflects electromagnetic waves above 1GHz and below 170GHz, preferably above 1GHz and below 100GHz, and more preferably above 1GHz and below 80GHz. Each reflection panel 10 has a conductive pattern or conductive film designed according to the reflection mode, frequency band, etc. as a target as a reflection film. The conductive film can also be formed by a periodic pattern, a grid pattern, a geometric pattern, a transparent film, etc. As described later, the relative dielectric constant and the dielectric loss tangent of the adhesive layer bonded to the conductive pattern on the reflection panel 10-1 are designed to be within a specified range, thereby suppressing the reduction of the reflection efficiency of the electromagnetic wave reflection device 60.

[0026] Each of the reflective panels 10-1, 10-2, and 10-3 may have a mirror reflective surface with an incident angle and an output angle of the electromagnetic wave being equal, or a non-mirror reflective surface with an incident angle and a reflection angle being different. In addition to a diffuse surface and a scattering surface, a non-mirror reflective surface also includes a metasurface which is an artificial reflective surface designed to reflect radio waves in a desired direction.

[0027] From the perspective of maintaining the continuity of the reflection potential, it is sometimes desirable that the reflection panels 10-1, 10-2, and 10-3 are electrically connected to each other, but in the case of including a metasurface, the adjacent reflection panels 10 may not be electrically connected. The adjacent reflection panels 10 are held by the frame 50, thereby obtaining an electromagnetic wave reflection fence 100 connected in the X direction.

[0028] The electromagnetic wave reflecting device 60 may also include a foot 56 for supporting the frame 50 in addition to the reflecting panel 10 and the frame 50. Figure 1 In this way, it is desirable to set the foot 56 when making the electromagnetic wave reflecting device 60 or the electromagnetic wave reflecting fence 100 self-standing on the setting surface, but the foot 56 is not essential. In addition to using the frame 50, a top frame 57 for holding the upper end of the reflecting panel 10 and a bottom frame 58 for holding the lower end may also be used. In this case, the frame 50, the top frame 57, and the bottom frame 58 constitute a frame for holding the entire circumference of the reflecting panel 10. The frame 50 may also be referred to as a "side frame" according to its positional relationship relative to the top frame 57 and the bottom frame 58. By setting the top frame 57 and the bottom frame 58, the mechanical strength and safety of the reflecting panel 10 during transportation and assembly are ensured. It is also possible that, depending on the different uses, the electromagnetic wave reflecting device 60 is set on a wall or a ceiling by holding the reflecting panel 10 through the frame 50, the top frame 57, and the bottom frame 58.

[0029] Figure 2 The cross-sectional view parallel to the XZ plane shows Figure 1 The frame 50 has a conductive body 500 and slits 51 formed on both sides of the body 500 in the width direction. The slits 51 hold the side edges of the reflective panel 10. The side edges of the reflective panel 10 are formed along the Figure 1 The edge in the Y direction.

[0030] The main body 500 includes a cavity 52 connected to the slit 51, a groove 53 provided in the cavity 52, and a hollow portion 55 not connected to the cavity 52 and the groove 53, but the present invention is not limited to this example. The groove 53 is provided at a position facing the slit 51 across the cavity 52, and holds the side edge of the reflection panel 10 inserted from the slit 51. By providing the cavity 52 and the hollow portion 55 in the frame 50, the frame 50 can be made lightweight. By providing the groove 53 in the cavity 52, the holding of the reflection panel 10 becomes more stable.

[0031] A non-conductive cover 501 made of resin or the like may be provided on the outer surface of the main body 500 , but the cover 501 is not essential. When the cover 501 is provided, the cover 501 functions as a protection member that protects the frame 50 .

[0032] Figure 3 The state of the reflection panel 10 being inserted into the frame 50 is shown in a cross-sectional view parallel to the XZ plane. Figure 2 ) is inserted into the reflective panels 10-1 and 10-2. The reflective panels 10-1 and 10-2 may not necessarily be inserted into the groove 53 of the cavity 52 (see Figure 2 ) to abut against the bottom surface of the groove 53. By inserting the reflection panels 10-1 and 10-2 into the slit 51, the adjacent reflection panels 10-1 and 10-2 can be stably held. A part of the body 500 can also be formed of a non-conductive material.

[0033] Figure 4A as well as Figure 4B An example of the layer structure of the reflection panel 10 is shown. The above-mentioned layer structure is the layer structure of the reflection panel 10 in the thickness (Z) direction. Figure 4A In the embodiment, the reflective panel 10A includes a dielectric layer 14, a conductive pattern 151 provided on one surface of the dielectric layer 14, a ground layer 13 provided on the surface on the opposite side of the dielectric layer 14, and an adhesive layer 153 for bonding the conductive pattern 151 to the dielectric layer 14. The adhesive layer 153 covers the entire surface of one surface of the dielectric layer 14. As described later, the adhesive layer 153 has a relative dielectric constant and a dielectric loss tangent within a predetermined range.

[0034] The dielectric layer 14 is an insulating polymer film such as polycarbonate, cycloolefin polymer (COP), polyethylene terephthalate (PET), or fluororesin, and has a thickness of about 0.3 mm to 1.0 mm. The dielectric layer 14 may be made of a material having a relative dielectric constant and a dielectric loss tangent suitable for achieving the desired reflection characteristics.

[0035] The conductive pattern 151 forms a reflective surface of the reflective panel 10. The reflective surface formed by the conductive pattern 151 may also include a metasurface whose reflective characteristics are artificially controlled. The conductive pattern 151 of the embodiment has a periodic pattern. The conductive pattern 151 is formed of a good conductor such as Cu, Ni, Ag, and has a thickness of 10 μm to 50 μm.

[0036] The adhesive layer 153 joins the conductive pattern 151 to the dielectric layer 14, and has a dielectric constant and a dielectric loss tangent within a specified range that can suppress the reduction of the reflection efficiency of the reflective panel 10. As the adhesive layer 153, a material that satisfies the composition of the specified dielectric constant and dielectric loss tangent among vinyl acetate resin, acrylic resin, cellulose resin, aniline resin, ethylene resin, silicone resin, and other resins can be used. The thickness of the adhesive layer 153 is 2 μm to 50 μm, and is preferably 10 μm to 50 μm from the viewpoint of ensuring the adhesive force.

[0037] Figure 4B In addition to Figure 4A In addition to the structure, it also has an intermediate layer 16 covering the conductive pattern 151, a dielectric substrate 17 connected to the conductive pattern 151 side through the intermediate layer 16, an intermediate layer 12 covering the ground layer 13, and a dielectric substrate 11 connected to the ground layer 13 side through the intermediate layer 12.

[0038] The intermediate layer 16 protects the surface of the conductive pattern 151 and adheres to and holds the dielectric substrate 17. The intermediate layer 16 is preferably durable and moisture-resistant, and can be made of, for example, ethylene-vinyl acetate (EVA) copolymer or cycloolefin polymer (COP). The thickness of the intermediate layer 16 is 10 μm to 400 μm.

[0039] The dielectric substrate 17 is the outermost layer of the reflection panel 10C and is preferably formed of a material having excellent impact resistance, durability, and transparency. Polycarbonate, acrylic resin, PET, etc. can be used as the dielectric substrate 17. The thickness of the dielectric substrate 17 is, for example, 1.0 mm to 10.0 mm.

[0040] The intermediate layer 12 protects the surface of the ground layer 13 and adheres to and holds the dielectric substrate 11. The intermediate layer 12 is preferably durable and moisture-resistant, and can be made of, for example, ethylene-vinyl acetate (EVA) copolymer or cycloolefin polymer (COP). The thickness of the intermediate layer 12 is 10 μm to 400 μm.

[0041] The dielectric substrate 11 is the outermost layer of the reflection panel 10C and is preferably formed of a material having excellent impact resistance, durability, and transparency. Polycarbonate, acrylic resin, PET, etc. can be used as the dielectric substrate 11. The thickness of the dielectric substrate 11 is, for example, 1.0 mm to 10.0 mm.

[0042] By covering the conductive pattern 151 with the intermediate layer 16 and bonding the dielectric substrate 17, the intrusion of moisture and air into the surface of the conductive pattern 151 is suppressed, and the degradation of the reflection surface is suppressed. By covering the ground layer 13 with the intermediate layer 12 and bonding the dielectric substrate 11, the intrusion of moisture and air into the surface of the ground layer 13 is suppressed, and the surface degradation of the ground layer 13 is suppressed. Thus, the capacitance between the ground layer 13 and the conductive pattern 151 is constantly maintained, and the designed phase delay can be maintained. That is, the reflection efficiency of the radio wave in the designed direction can be maintained.

[0043] From the viewpoint of maintaining the reflection efficiency of the reflection panel 10 at 60% or more, more preferably at 70% or more, the relative dielectric constant and dielectric loss tangent of the adhesive layer 153 are designed to be within an appropriate range. Specifically, it is desirable that the relative dielectric constant of the adhesive layer 153 is 2.0 or more and less than 3.0, and the dielectric loss tangent is greater than 0.00 and less than 0.10 in the range of 1 GHz or more and 30 GHz or less, or the relative dielectric constant is 3.0 or more and less than 4.5, and the dielectric loss tangent is greater than 0.00 and less than 0.02.

[0044] Generally, in order to suppress the loss of electric energy inside the adhesive layer 153, it is desirable that the dielectric loss tangent is low. With respect to the relative dielectric constant, if the relative dielectric constant becomes higher, the loss especially relative to high frequency becomes larger. On the other hand, there is also a relationship between the relative dielectric constant and the dielectric loss tangent of the dielectric layer 14. Therefore, the appropriate range of the dielectric constant and the dielectric loss tangent of the adhesive layer 153 is studied to maintain the reflection efficiency at more than 60%.

[0045] Figure 5A model 21 of a conductive pattern 151 used for evaluation of a reflective panel 10 is shown. The evaluation model 21 includes a periodic arrangement of unit cells (also referred to as "super cells") 210. The unit cells 210 are arranged in 6 rows in the X direction and 36 rows in the Y direction, forming a metasurface that reflects electromagnetic waves at an angle different from the incident angle.

[0046] Figure 6 2 is a schematic diagram showing the structure of the unit cell 210 of the model 21. The unit cell 210 is formed by six metal patches 211, 212, 213, 214, 215, and 216. The width (W) direction and length (L) of the metal patches 211-216 are respectively Figure 1 The width (X) direction and the height (Y) direction of the reflective panel 10 correspond. For the metal patches 211-216, the width W is equal, and although the length L is different, the central axis of the length is consistent (the Y coordinate position of the central axis is constant). The spacing in the X direction is constant. The phase of reflection is controlled by setting the shape and size of the metal patches 211-216 with the gap G between the metal patches in a manner to form a prescribed spacing, and a reflected beam is formed in a desired direction by overlapping the reflected waves. In this example, the unit cell 210 is designed so that the peak of the reflected wave of the vertically incident electromagnetic wave (incident angle 0°) appears in a direction 50° from the normal.

[0047] In the evaluation, use Figure 5 The conductive pattern 151 of model 21 is subjected to a 1 GHz and 28.0 GHz plane wave incident at an incident angle of 0° using a general three-dimensional electromagnetic field simulation software, and the scattering cross-sectional area of ​​the reflected wave is analyzed. The scattering cross-sectional area, namely the radar reflection cross-sectional area (RCS), is used as an indicator of the ability to reflect incident electromagnetic waves.

[0048] In the case of a metasurface that reflects at a reflection angle different from the incident angle, the calculated power reflection efficiency needs to be corrected. An ideal conductive plate is completely mirror-reflective, reflecting electromagnetic waves in the same direction relative to vertical incidence, whereas a metasurface reflects electromagnetic waves in a direction different from the incident angle. The power reflection efficiency of the metasurface is obtained by dividing the power reflection efficiency calculated from the gain value by the correction value.

[0049] If it will pass Figure 5 The reflected electric field of the lossless metasurface determined by the model pattern is set to E MR , let the reflected electric field of the ideal conductive plate be E PEC , then the correction value ε p For |E MR / E PEC | 2 . |E MR / EPEC | is represented as

[0050] Number 1

[0051]

[0052] or,

[0053] Number 2

[0054]

[0055] Here, θ is the incident angle to the metasurface, If the reflection angle of the metasurface is set to θ = 50° or θr = 50°, and the incident angle θi = 0°, the reflection angle of normal reflection is Then the correction value ε p It is 0.7826.

[0056] Figure 7 The analytical space 101 of the electromagnetic wave simulation is shown. The thickness direction of the layer structure of the reflection panel 10 is defined as the Z direction. Figure 5 The width direction of the metal patch of the model 21 is the X direction, and the length direction is the Y direction. The analytical space is represented by (dimension in the X direction) × (dimension in the Y direction) × (dimension in the Z direction). The size of the analytical space 101 when the frequency of the incident electromagnetic wave is 28.0 GHz is 83.9 mm × 192.6 mm × 3.7 mm. The boundary condition is a design in which an electromagnetic wave absorber 102 is arranged around the analytical space 101.

[0057] Fig. 8A is a schematic diagram of the XY plane of the analytical space 101 surrounded by the electromagnetic wave absorber 102, Figure 8B is a schematic diagram of the XZ plane of analytical space 101. Figure 8C Schematic diagram of the YZ plane of the analytical space 101. In the analytical space 101, the relative dielectric constant and dielectric loss tangent of the adhesive layer 153 carrying the conductive pattern 151 are changed to calculate the power reflection efficiency. All the conductive patterns 151 used in the simulation are shared. The 6 conductive patterns 151 constituting the unit cell 210 are made into a rectangular shape with a width W of 0.4 mm, and the lengths L are 2.9751 mm, 3.0739 mm, 3.7536 mm, 2.0344 mm, 2.7300 mm and 2.8497 mm respectively. The spacing between the metal patches in the X direction (i.e., the center-to-center distance) is 1.9283 mm.

[0058] <Example 1>

[0059] As the dielectric layer 14, a polycarbonate film with a thickness of 0.7 mm is used. On one surface of the polycarbonate film, a ground layer 13 is set by an Ag-based multilayer film with a thickness of 0.36 mm. On the other surface of the polycarbonate film, a conductive pattern 151 is configured via an adhesive layer 153 with a thickness of 0.05 mm provided on the entire surface. The conductive pattern 151 is formed of a copper foil with a thickness of 0.05 mm and has a pattern shape of the above-mentioned unit cell 210. The relative dielectric constant of the adhesive layer 153 at 28 GHz is 2.0, and the dielectric loss tangent is 0.01. The gain value (peak value of the reflected waveform) at 50° of the RCS curve when a 28.0 GHz plane wave incident at an incident angle of 0° is reflected at a reflection angle of 50° is 11.0450 dB. According to the correction value ε p = 0.7826 The power reflection efficiency after correcting the gain value is 69.6%. According to the relative dielectric constant and dielectric loss tangent of the adhesive layer 153 of Example 1, a power reflection efficiency of 60% or more is obtained.

[0060] <Example 2>

[0061] In Example 2, except that the dielectric loss tangent of the adhesive layer 153 is set to 0.02, the other conditions are the same as those in Example 1. That is, a polycarbonate film with a thickness of 0.7 mm is used as the dielectric layer 14. On one surface of the polycarbonate film, the ground layer 13 is set by an Ag-based multilayer film with a thickness of 0.36 mm. On the other surface of the polycarbonate film, a conductive pattern 151 formed by a copper foil with a thickness of 0.05 mm is arranged via an adhesive layer 153 with a thickness of 0.05 mm provided on the entire surface. The relative dielectric constant of the adhesive layer 153 at 28 GHz is 2.0, and the dielectric loss tangent is 0.02. When a plane wave of 28.0 GHz incident at an angle of incidence of 0° is reflected at a reflection angle of 50°, the gain value (peak value of the reflected waveform) at 50° of the RCS curve is 10.9815 dB. According to the correction value ε p = 0.7826 After correcting the gain value, the power reflection efficiency is 68.6%. According to the relative dielectric constant and dielectric loss tangent of the adhesive layer 153 of Example 2, a power reflection efficiency of 60% or more is obtained.

[0062] <Example 3>

[0063] In Example 3, except that the dielectric loss tangent of the adhesive layer 153 is set to 0.03, the other conditions are the same as those of Examples 1 and 2. That is, a polycarbonate film with a thickness of 0.7 mm is used as the dielectric layer 14. On one surface of the polycarbonate film, the ground layer 13 is set by an Ag-based multilayer film with a thickness of 0.36 mm. On the other surface of the polycarbonate film, a conductive pattern 151 formed by a copper foil with a thickness of 0.05 mm is arranged via an adhesive layer 153 with a thickness of 0.05 mm provided on the entire surface. The relative dielectric constant of the adhesive layer 153 at 28 GHz is 2.0, and the dielectric loss tangent is 0.03. When a plane wave of 28.0 GHz incident at an angle of incidence of 0° is reflected at a reflection angle of 50°, the gain value (peak value of the reflected waveform) at 50° of the RCS curve is 10.8111 dB. According to the correction value ε p = 0.7826 After correcting the gain value, the power reflection efficiency is 65.9%. According to the relative dielectric constant and dielectric loss tangent of the adhesive layer 153 of Example 3, a power reflection efficiency of 60% or more is obtained.

[0064] <Example 4>

[0065] In Example 4, except that the relative dielectric constant of the adhesive layer 153 is set to 2.5, the other conditions are the same as those in Example 1. That is, a polycarbonate film with a thickness of 0.7 mm is used as the dielectric layer 14. On one surface of the polycarbonate film, the ground layer 13 is set by an Ag-based multilayer film with a thickness of 0.36 mm. On the other surface of the polycarbonate film, a conductive pattern 151 formed by a copper foil with a thickness of 0.05 mm is arranged via an adhesive layer 153 with a thickness of 0.05 mm provided on the entire surface. The relative dielectric constant of the adhesive layer 153 at 28 GHz is 2.5, and the dielectric loss tangent is 0.01. When a plane wave of 28.0 GHz incident at an angle of incidence of 0° is reflected at a reflection angle of 50°, the gain value (peak value of the reflected waveform) at 50° of the RCS curve is 11.3079 dB. According to the correction value ε p =0.7826 After correcting the gain value, the power reflection efficiency is 73.9%.

[0066] In Example 4, although the relative dielectric constant of the adhesive layer 153 at 28 GHz is increased to 2.5, a power reflection efficiency of more than 70% is achieved. It is also believed that this is because the difference with the relative dielectric constant (2.785) of the polycarbonate of the dielectric layer 14 at 28 GHz becomes smaller. In Example 4, the relative dielectric constant is further fixed to 2.5, and the dielectric loss tangent is increased to 0.02 and 0.03 to calculate the power reflection efficiency. When the relative dielectric constant is 2.5 and the dielectric loss tangent is 0.02, the gain value at 50° is 11.1920 dB. According to the correction value ε p=0.7826 After correcting the gain value, the power reflection efficiency is 72.0%. If the relative dielectric constant is 2.5 and the dielectric loss tangent is 0.03, the gain value at 50° is 11.0800dB, and according to the correction value ε p =0.7826 After correcting the gain value, the power reflection efficiency is 70.2%, and a power reflection efficiency of more than 70% can be achieved.

[0067] <Example 5>

[0068] In Example 5, except that the relative dielectric constant of the adhesive layer 153 is set to 3.0, the other conditions are the same as those of Example 4. That is, a polycarbonate film with a thickness of 0.7 mm is used as the dielectric layer 14. On one surface of the polycarbonate film, the ground layer 13 is set by an Ag-based multilayer film with a thickness of 0.36 mm. On the other surface of the polycarbonate film, a conductive pattern 151 formed by a copper foil with a thickness of 0.05 mm is arranged via an adhesive layer 153 with a thickness of 0.05 mm provided on the entire surface. The relative dielectric constant of the adhesive layer 153 at 28 GHz is 3.0, and the dielectric loss tangent is 0.01. When a plane wave of 28.0 GHz incident at an angle of incidence of 0° is reflected at a reflection angle of 50°, the gain value (peak value of the reflected waveform) at 50° of the RCS curve is 10.5895 dB. According to the correction value ε p =0.7826 After correcting the gain value, the power reflection efficiency is 62.7%.

[0069] In Example 5, although the loss of high-frequency energy is increased by increasing the relative dielectric constant of the adhesive layer 153 at 28 GHz to 3.0, the matching property with the relative dielectric constant of the dielectric layer 14 is good, and the power reflection efficiency of more than 60% is achieved. In Example 5, the relative dielectric constant is further fixed to 3.0, and the dielectric loss tangent is increased to 0.02 to calculate the power reflection efficiency. When the relative dielectric constant is 3.0 and the dielectric loss tangent is 0.02, the gain value at 50° is 10.4950 dB. According to the correction value ε p =0.7826 After correcting the gain value, the power reflection efficiency is 61.3%, and a power reflection efficiency of more than 60% can be achieved.

[0070] <Example 6>

[0071] In Example 6, except that the relative dielectric constant of the adhesive layer 153 is set to 3.5, the other conditions are the same as those of Example 4. That is, a polycarbonate film with a thickness of 0.7 mm is used as the dielectric layer 14. On one surface of the polycarbonate film, the ground layer 13 is set by an Ag-based multilayer film with a thickness of 0.36 mm. On the other surface of the polycarbonate film, a conductive pattern 151 formed by a copper foil with a thickness of 0.05 mm is arranged via an adhesive layer 153 with a thickness of 0.05 mm provided on the entire surface. The relative dielectric constant of the adhesive layer 153 at 28 GHz is 3.5, and the dielectric loss tangent is 0.01. When a plane wave of 28.0 GHz incident at an angle of incidence of 0° is reflected at a reflection angle of 50°, the gain value (peak value of the reflected waveform) at 50° of the RCS curve is 10.5542 dB. According to the correction value ε p =0.7826 After correcting the gain value, the power reflection efficiency is 62.2%.

[0072] In Example 6, the relative dielectric constant of the adhesive layer 153 at 28 GHz is increased to 3.5, thereby increasing the loss of high-frequency energy compared to Example 5. However, the power reflection efficiency of more than 60% is still achieved. In Example 6, the relative dielectric constant is further fixed to 3.5, and the dielectric loss tangent is increased to 0.02 to calculate the power reflection efficiency. When the relative dielectric constant is 3.5 and the dielectric loss tangent is 0.02, the gain value at 50° is 10.4760 dB. According to the correction value ε p =0.7826 After correcting the gain value, the power reflection efficiency is 61.0%, and a power reflection efficiency of more than 60% can be achieved.

[0073] <Example 7>

[0074] In Example 7, except that the relative dielectric constant of the adhesive layer 153 is set to 4.0, the other conditions are the same as those of Example 4. That is, a polycarbonate film with a thickness of 0.7 mm is used as the dielectric layer 14. On one surface of the polycarbonate film, the ground layer 13 is set by an Ag-based multilayer film with a thickness of 0.36 mm. On the other surface of the polycarbonate film, a conductive pattern 151 formed by a copper foil with a thickness of 0.05 mm is arranged via an adhesive layer 153 with a thickness of 0.05 mm provided on the entire surface. The relative dielectric constant of the adhesive layer 153 at 28 GHz is 4.0, and the dielectric loss tangent is 0.01. When a plane wave of 28.0 GHz incident at an angle of incidence of 0° is reflected at a reflection angle of 50°, the gain value (peak value of the reflected waveform) at 50° of the RCS curve is 10.7307 dB. According to the correction value ε p =0.7826 After correcting the gain value, the power reflection efficiency is 64.7%.

[0075] In Example 7, even if the relative dielectric constant of the adhesive layer 153 at 28 GHz is increased to 4.0, the power reflection efficiency of more than 60% is still achieved. In Example 7, the relative dielectric constant is further fixed to 4.0 and the dielectric loss tangent is increased to 0.02 to calculate the power reflection efficiency. When the relative dielectric constant is 4.0 and the dielectric loss tangent is 0.02, the gain value at 50° is 10.5500 dB. According to the correction value ε p =0.7826 After correcting the gain value, the power reflection efficiency is 62.1%, and a power reflection efficiency of more than 60% can be achieved.

[0076] <Example 8>

[0077] In Example 8, except that the dielectric loss tangent of the adhesive layer 153 at 28 GHz is set to 0.05 and the relative dielectric constant is changed to 2.00 and 2.50, the other conditions are the same as those of Example 4. When the relative dielectric constant is 2.00 and the dielectric loss tangent is 0.05, the gain value (peak value of the reflected waveform) at 50° of the RCS curve when a 28.0 GHz plane wave incident at an incident angle of 0° is reflected at a reflection angle of 50° is 10.6191 dB. According to the correction value ε p =0.7826 After correcting the gain value, the power reflection efficiency is 63.1%. When the relative dielectric constant is 2.50 and the dielectric loss tangent is 0.05, the gain value (peak value of the reflected waveform) at 50° of the RCS curve when a 28.0GHz plane wave incident at an incident angle of 0° is reflected at a reflection angle of 50° is 10.8744dB. According to the correction value ε p = 0.7826 After correcting the gain value, the power reflection efficiency is 66.9%. When the relative dielectric constant is 2.5, the dielectric loss tangent is less than 0.05, and a reflection efficiency of more than 60% is obtained.

[0078] <Example 9>

[0079] In Example 9, the appropriate range of the relative dielectric constant and the dielectric loss tangent at 1 GHz is studied. Except for the relative dielectric constant of the adhesive layer 153, the other conditions are the same as those in Example 1. That is, as the dielectric layer 14, a polycarbonate film with a thickness of 0.7 mm is used. On one surface of the polycarbonate film, a grounding layer 13 is set by an Ag-based multilayer film with a thickness of 0.36 mm. On the other surface of the polycarbonate film, a conductive pattern 151 formed by a copper foil with a thickness of 0.05 mm is arranged via an adhesive layer 153 with a thickness of 0.05 mm provided on the entire surface. Calculate the gain value (peak value of the reflected waveform) at 50° of the RCS curve when a 1.0 GHz plane wave incident at an angle of incidence of 0° is reflected at a reflection angle of 50°, and calculate the correction value ε p=0.7826The power reflection efficiency after correcting the gain value.

[0080] If the dielectric loss tangent of the adhesive layer 153 at 1 GHz is fixed to 0.01 and the relative dielectric constant is increased from 2.1, the relative dielectric constant is less than 4.5, and a power reflection efficiency of more than 60% is obtained. In particular, a relative dielectric constant of 2.1 is obtained, a power reflection efficiency of 69.6% is obtained, a relative dielectric constant of 2.2 or more and less than 2.7 is obtained, and a power reflection efficiency of 70% or more is obtained, and a relative dielectric constant of 2.1 is obtained. Table 1 shows the specific calculation results of the relative dielectric constant, gain value, and corrected power reflection efficiency when the dielectric loss tangent is 0.01.

[0081] Table 1: Table @

[0082]

[0083] <Example 10>

[0084] In Example 10, the relative dielectric constant of the adhesive layer 153 at 1 GHz was fixed at 2.1, and the dielectric loss tangent was increased to 0.02, 0.03, 0.05, 0.08, and 0.09. The other conditions and evaluation methods were the same as those of Examples 1 to 9. When the relative dielectric constant at 1 GHz was 2.1, the gain value of the RCS curve at an incident angle of 0° and a reflection angle of 50° and the power reflection efficiency after correction by the correction value εp=0.7826 were as follows.

[0085] When the dielectric loss tangent is 0.02, the gain value is 11.1414dB and the power reflection efficiency is 71.1%

[0086] When the dielectric loss tangent is 0.03, the gain value is 11.0006dB and the power reflection efficiency is 68.9%

[0087] When the dielectric loss tangent is 0.05, the gain value is 10.8475dB and the power reflection efficiency is 66.5%

[0088] When the dielectric loss tangent is 0.08, the gain value is 10.53304dB and the power reflection efficiency is 61.8%

[0089] When the dielectric loss tangent is 0.09, the gain value is 10.4147dB and the power reflection efficiency is 60.2%

[0090] Thus, when the relative dielectric constant is 2.1, a power reflection efficiency of 60% or more is obtained with respect to an electromagnetic wave of 1 GHz in a range where the dielectric loss tangent is greater than 0.00 and less than 0.09.

[0091] <Example 11>

[0092] In Example 11, the relative dielectric constant of the adhesive layer 153 at 1 GHz was fixed at 2.3, and the dielectric loss tangent was increased to 0.02, 0.03, 0.05, 0.08, 0.09, and 0.10. The other conditions and evaluation methods were the same as those of Examples 1 to 10. When the relative dielectric constant at 1 GHz was 2.3, the gain value of the RCS curve at an incident angle of 0° and a reflection angle of 50° and the correction value ε p =0.7826 The power reflection efficiency after correction is as follows.

[0093] When the dielectric loss tangent is 0.02, the gain value is 11.2100dB and the power reflection efficiency is 72.3%

[0094] When the dielectric loss tangent is 0.03, the gain value is 11.1410dB and the power reflection efficiency is 71.1%

[0095] When the dielectric loss tangent is 0.05, the gain value is 10.9537dB and the power reflection efficiency is 68.1%

[0096] When the dielectric loss tangent is 0.08, the gain value is 10.6827dB and the power reflection efficiency is 64.0%

[0097] When the dielectric loss tangent is 0.09, the gain value is 10.5260dB and the power reflection efficiency is 61.7%

[0098] When the dielectric loss tangent is 0.10, the gain value is 10.4297dB and the power reflection efficiency is 60.4%

[0099] Thus, when the relative dielectric constant is 2.3, a power reflection efficiency of 60% or more is obtained with respect to an electromagnetic wave of 1 GHz in a range where the dielectric loss tangent is greater than 0.00 and less than 0.10.

[0100] <Example 12>

[0101] In Example 12, the relative dielectric constant of the adhesive layer 153 at 1 GHz was fixed at 2.5, and the dielectric loss tangent was increased to 0.02, 9.93, 0.05, 0.08, and 0.09. The other conditions and evaluation methods were the same as those of Examples 1 to 10. When the relative dielectric constant at 1 GHz was 2.5, the gain value of the RCS curve at an incident angle of 0° and a reflection angle of 50° and the correction value ε p =0.7826 The power reflection efficiency after correction is as follows.

[0102] When the dielectric loss tangent is 0.02, the gain value is 11.1920dB and the power reflection efficiency is 72.0%

[0103] When the dielectric loss tangent is 0.03, the gain value is 11.0800dB and the power reflection efficiency is 70.2%

[0104] When the dielectric loss tangent is 0.05, the gain value is 10.8774dB and the power reflection efficiency is 66.9%

[0105] When the dielectric loss tangent is 0.08, the gain value is 10.5331dB and the power reflection efficiency is 61.8%

[0106] When the dielectric loss tangent is 0.09, the gain value is 10.4354dB and the power reflection efficiency is 60.5%

[0107] Thus, when the relative dielectric constant is 2.5, a power reflection efficiency of 60% or more is obtained with respect to an electromagnetic wave of 1 GHz in a range where the dielectric loss tangent is greater than 0.00 and less than 0.09.

[0108] <Example 13>

[0109] In Example 13, the relative dielectric constant of the adhesive layer 153 was changed to 3.0, 3.5, and 4.0 under the condition of 1 GHz, and the dielectric loss tangent was increased from 0.01 in units of 0.01 for each relative dielectric constant. Other conditions and evaluation methods were the same as those of Examples 1 to 10. The following results were obtained by calculation.

[0110] When the relative dielectric constant is 3.0, the dielectric loss tangent is 0.02, the gain is 10.4950dB, and the corrected power reflection efficiency is 61.3%

[0111] When the relative dielectric constant is 3.5, the dielectric loss tangent is 0.02, the gain is 10.4760dB, and the corrected power reflection efficiency is 61.0%

[0112] When the relative dielectric constant is 4.0, the dielectric loss tangent is 0.02, the gain is 10.631dB, and the corrected power reflection efficiency is 63.3%

[0113] <Comparative Example 1>

[0114] In Comparative Example 1, except that the relative dielectric constant of the adhesive layer 153 is set to 4.5, the other conditions are the same as those of Example 1. That is, the relative dielectric constant of the adhesive layer 153 with a thickness of 0.05 mm at 28 GHz is 4.5, and the dielectric loss tangent is 0.01. When a 28.0 GHz plane wave incident at an incident angle of 0° is reflected at a reflection angle of 50°, the gain value at 50° of the RCS curve is 10.3184 dB. According to the correction value ε p = 0.7826 After correcting the gain value, the power reflection efficiency is 58.9%, and a power reflection efficiency of 60% or more cannot be achieved.

[0115] <Comparative Example 2>

[0116] In Comparative Example 2, except that the relative dielectric constant of the adhesive layer 153 is set to 4.5, the other conditions are the same as those of Example 2. That is, the relative dielectric constant of the adhesive layer 153 with a thickness of 0.05 mm at 28 GHz is 4.5, and the dielectric loss tangent is 0.02. When a 28.0 GHz plane wave incident at an incident angle of 0° is reflected at a reflection angle of 50°, the gain value at 50° of the RCS curve is 10.2456 dB. According to the correction value ε p = 0.7826 After correcting the gain value, the power reflection efficiency is 57.9%, and a power reflection efficiency of 60% or more cannot be achieved.

[0117] <Comparative Example 3>

[0118] In Comparative Example 3, except that the relative dielectric constant of the adhesive layer 153 is set to 4.5, the other conditions are the same as those of Example 3. That is, the relative dielectric constant of the adhesive layer 153 with a thickness of 0.05 mm at 28 GHz is 4.5, and the dielectric loss tangent is 0.03. When a 28.0 GHz plane wave incident at an incident angle of 0° is reflected at a reflection angle of 50°, the gain value at 50° of the RCS curve is 10.1244 dB. According to the correction value ε p = 0.7826 After correcting the gain value, the power reflection efficiency is 56.3%, and a power reflection efficiency of 60% or more cannot be achieved.

[0119] <Comparative Example 4>

[0120] In Comparative Example 4, the relative dielectric constant of the adhesive layer 153 at 28 GHz is fixed at 3.0, and the dielectric loss tangent is changed to 0.03, 0.05, and 0.10. The other conditions are the same as those in Example 1. When the dielectric loss tangent is 0.03, the gain value at 50° of the RCS curve when a 28.0 GHz plane wave incident at an incident angle of 0° is reflected at a reflection angle of 50° is 10.3733 dB. According to the correction value ε p=0.7826 After correcting the gain value, the power reflection efficiency is 59.6%, which cannot achieve a power reflection efficiency of more than 60%. When the dielectric loss tangent is 0.05, the corrected power reflection efficiency is reduced to 57.6%, and when the dielectric loss tangent is 0.10, the corrected power reflection efficiency is further reduced.

[0121] <Comparative Example 5>

[0122] In Comparative Example 5, the relative dielectric constant of the adhesive layer 153 at 28 GHz is set to 3.5, and the dielectric loss tangent is set to 0.03. Other conditions are the same as those in Example 1. When a 28.0 GHz plane wave incident at an incident angle of 0° is reflected at a reflection angle of 50°, the gain value at 50° of the RCS curve is 10.2962 dB. According to the correction value ε p = 0.7826 After correcting the gain value, the power reflection efficiency is 58.6%, and a power reflection efficiency of 60% or more cannot be achieved.

[0123] <Comparative Example 6>

[0124] In Comparative Example 4, the relative dielectric constant of the adhesive layer 153 at 28 GHz is set to 4.00, and the dielectric loss tangent is set to 0.03. Other conditions are the same as those in Example 1. When a 28.0 GHz plane wave incident at an incident angle of 0° is reflected at a reflection angle of 50°, the gain value at 50° of the RCS curve is 10.3971 dB. According to the correction value ε p =0.7826 After correcting the gain value, the power reflection efficiency is 59.9%, and a power reflection efficiency of 60% or more cannot be achieved.

[0125] <Comparative Example 7>

[0126] In Comparative Example 7, the relative dielectric constant of the adhesive layer 153 at 1 GHz was fixed at 4.5, and the dielectric loss tangent was changed to 0.01, 0.02, and 0.03. Other conditions and evaluation methods were the same as those of Examples 1 to 8. When the relative dielectric constant at 1 GHz was 4.5, the following results were obtained by calculation.

[0127] Dielectric loss tangent of 0.01, 58.9% power reflection efficiency

[0128] Dielectric loss tangent of 0.02, 57.9% power reflection efficiency

[0129] Dielectric loss tangent of 0.03, 56.3% power reflection efficiency

[0130] <Comparative Example 8>

[0131] In Comparative Example 8, the dielectric loss tangent of the adhesive layer 153 at 1 GHz was fixed at 0.10, and the relative dielectric constant was changed to 2.1, 2.5, and 3.0. Other conditions and evaluation methods were the same as those of Examples 1 to 8. When the dielectric loss tangent at 1 GHz was 0.10, the following results were obtained by calculation.

[0132] · Relative dielectric constant of 2.1, 59.0% power reflection efficiency

[0133] · Relative dielectric constant of 2.5, 47.0% power reflection efficiency

[0134] · Relative dielectric constant of 3.0, power reflection efficiency of 50.9%

[0135] Fig. 9 The relationship between the relative dielectric constant and dielectric loss tangent of the adhesive layer 153 and the power reflection efficiency at 28 GHz is shown. Fig. 9 The results correspond to Examples 1 to 8 and Comparative Examples 1 to 4. The vertical column is the relative dielectric constant at 28 GHz, and shows the power reflection efficiency when the dielectric loss tangent is 0.01, 0.02, 0.03, 0.05, 0, and 10. "A" indicates a combination that obtains a power reflection efficiency of 60% or more, and "B" indicates a combination that obtains a power reflection efficiency of less than 60%.

[0136] With respect to electromagnetic waves at 28 GHz, when the relative dielectric constant of the adhesive layer is 4.0 or less and the dielectric loss tangent is 0.02 or less, a power reflection efficiency of 60% or more is obtained. Among them, in the range of relative dielectric constant of 2.0 or more and 2.5 or less, the dielectric loss tangent is 0.05 or less and a power reflection efficiency of 60% or more is obtained. On the other hand, if the relative dielectric constant is 4.5 or more, even if the dielectric loss tangent is reduced, a power reflection efficiency of 60% or more cannot be obtained.

[0137] Fig.10 The relationship between the relative dielectric constant and dielectric loss tangent of the adhesive layer 153 and the power reflection efficiency at 1 GHz is shown. Fig.10 The results correspond to those of Examples 9-13 and Comparative Examples 5-8. The vertical column shows the relative dielectric constant at 1 GHz, and the power reflection efficiency when the dielectric loss tangent is 0.01, 0.02, 0.03, 0.05, 0.08, 0.09, and 0.10. Fig. 9 Similarly, "A" indicates a combination that achieves a power reflection efficiency of 60% or more, and "B" indicates a combination that achieves a power reflection efficiency of less than 60%.

[0138] When the relative dielectric constant of the adhesive layer 153 is less than 4.0 and the dielectric loss tangent is less than 0.02 with respect to an electromagnetic wave of 1 GHz, a power reflection efficiency of more than 60% is obtained. In addition, according to Example 9, when the dielectric loss tangent is 0.01, the relative dielectric constant of the adhesive layer 153 is less than 4.5, and a power reflection efficiency of more than 60% is obtained. Among them, in the range of the relative dielectric constant being greater than 2.1 and less than 2.9, the dielectric loss tangent is less than 0.03, and a higher power reflection efficiency is obtained. On the other hand, if the relative dielectric constant is greater than 4.5, even if the dielectric loss tangent is reduced, a power reflection efficiency of more than 60% cannot be obtained.

[0139] according to Fig. 9 , Fig.10 The results of Examples 1-13 and Comparative Examples 1-8 shown in the figure show that, in the case where an adhesive layer 153 is provided that covers the entire surface of the dielectric layer 14, when the relative dielectric constant of the adhesive layer 153 is greater than 2.0 and less than 3.0, and the dielectric loss tangent is greater than 0.00 and less than 0.10 in the range of 1 GHz to 30 GHz, a power reflection efficiency of 60% or more is obtained. In addition, when the relative dielectric constant of the adhesive layer 153 is greater than 3.0 and less than 4.5 and greater than the dielectric loss tangent of 0.00 and less than 0.02, a power reflection efficiency of 60% or more is achieved. In particular, a higher power reflection efficiency is obtained when the relative dielectric constant is greater than 2.2 and less than 2.7 and the dielectric loss tangent is greater than 0.00 and less than 0.09.

[0140] In the above-mentioned embodiments 1-13, the calculation is performed when the higher frequency is 28 GHz, but there is almost no difference in the calculation results within the range of 28 GHz ± 4 GHz, and the calculation results are very similar within the range of 1 GHz to 28 GHz ± 2 GHz. The smaller the dielectric loss tangent, the smaller the loss of reflected energy. Therefore, when the dielectric loss tangent is less than 0.01, an electric power reflection efficiency of more than 60% is obtained. For example, under the above-mentioned evaluation conditions, when the relative dielectric constant at 28 GHz is 2.0 and the dielectric loss tangent is 0.001, the gain value at 50° of the RCS curve is 11.1541 dB, and the corrected electric power reflection efficiency is 71.4%. When the relative dielectric constant at 28 GHz is 2.5 and the dielectric loss tangent is 0.001, the gain value at 50° of the RCS curve is 11.4248 dB, and the corrected electric power reflection efficiency is 75.9%. Such a higher electric power reflection efficiency is also applicable when the frequency of the incident electromagnetic wave is 1 GHz. In Example 1-13, the thickness of the conductive pattern 151 is calculated to be 0.05 mm, but the power reflection efficiency is not significantly affected by the thickness of the conductive pattern 151. Even when the thickness of the conductive pattern 151 is 0.01 mm to 0.05 mm, the above-mentioned ranges of the relative dielectric constant and the dielectric loss tangent of the adhesive layer 153 are applicable.

[0141] Rather than the thickness of the conductive pattern 151, the power reflection efficiency is affected by the occupancy rate of the conductive pattern relative to the dielectric layer 14. The occupancy rate of the conductive pattern 151 bonded by the adhesive layer 153 is, for example, not less than 10.0% and not more than 45.0%. When the occupancy rate of the conductive pattern 151 is less than 10%, it is sometimes difficult to achieve the reflection characteristics and reflection efficiency in the desired direction. If the occupancy rate of the conductive pattern 151 exceeds 45%, there is a possibility that the transmittance relative to visible light is reduced. In applications where the reflective panel 10 does not require transparency, the occupancy rate of the conductive pattern 151 may also exceed 45%.

[0142] The above ranges of the relative dielectric constant and dielectric loss tangent of the adhesive layer 153 also apply to Figure 4B That is, the conductive pattern 151 bonded by the adhesive layer 153 having a relative dielectric constant of 2.0 or more and less than 3.0 and a dielectric loss tangent of more than 0.00 and less than 0.10 or the adhesive layer 153 having a relative dielectric constant of 3.0 or more and less than 4.5 and a dielectric loss tangent of more than 0.00 and less than 0.02 may be covered by the intermediate layer 16. By covering the conductive pattern 151 and the adhesive layer 153 with the intermediate layer 16, changes in the surface state of the conductive pattern 151 caused by the influence of oxygen, moisture, etc. can be suppressed, and durability is improved.

[0143] When the dielectric substrate 17 is bonded to the conductive pattern 151 through the intermediate layer 16, the impact resistance and durability of the reflective panel 10 are improved. In this case, the thickness of the intermediate layer 16 can be a thickness that can ensure moisture resistance and protection with respect to the conductive pattern 151 and can bond to the dielectric substrate 17. As the intermediate layer 16, for example, an adhesive film with a thickness of 10 μm or more and 400 μm or less can be used. The intermediate layer 12 provided on the ground layer 13 side is the same.

[0144] The electromagnetic wave reflection device of the embodiment is not limited to the above-mentioned structural example. The reflection angle relative to vertical incidence can be appropriately designed within a range of more than 35° and less than 90° by designing the size, shape, spacing of the conductive pattern 151, and the dielectric constant of the dielectric layer 14. The in-plane dimensions of the reflection panel 10 of the electromagnetic wave reflection device can be appropriately selected within the range of 30cm×30cm to 3m×3m. The entire surface of the reflection panel 10 can also be made into a super surface, a part of it can be made into a super surface, and the remaining part can be made into a mirror reflection surface. In this case, the entire surface of the reflection surface can also be covered with a moisture-resistant and durable adhesive film (intermediate layer) and bonded to the dielectric substrate.

[0145] This application claims priority based on Japanese Patent Application No. 2022-089850 filed on June 1, 2022, and includes all the contents of the Japanese Patent Application.

[0146] Description of Reference Numerals

[0147] 10, 10-1, 10-2, 10-3...reflective panel; 11, 17...dielectric substrate; 12, 16...middle layer; 13...ground layer; 14...dielectric layer; 151...conductive pattern; 153...adhesive layer; 50...frame (side frame); 57...top frame; 58...bottom frame; 60, 60-1, 60-2, 60-3...electromagnetic wave reflecting device; 100...electromagnetic wave reflecting fence; 210...unit cell.

Claims

1. An electromagnetic wave reflection device, characterized in that: have: a reflective panel that reflects radio waves in a desired frequency band selected from a frequency band of 1 GHz to 170 GHz; and a frame which holds the reflective panel, The reflective panel comprises: a dielectric layer, a periodic conductive pattern provided on one surface of the dielectric layer, a ground layer provided on the other surface of the dielectric layer, and an adhesive layer for bonding the conductive pattern to the one surface of the dielectric layer. The adhesive layer covers the entire surface of the one surface of the dielectric layer, In the range of 1 GHz to 30 GHz, the relative dielectric constant of the adhesive layer is 2.0 to 3.0 and the dielectric loss tangent is greater than 0.00 and less than 0.10, or the relative dielectric constant of the adhesive layer is 3.0 to 4.5 and the dielectric loss tangent is greater than 0.00 and less than 0.

02.

2. The electromagnetic wave reflection device according to claim 1, characterized in that: At the frequency of 1 GHz to 30 GHz, the relative dielectric constant of the adhesive layer is 2.2 to 2.7, and the dielectric loss tangent is 0.09 to 0.

09.

3. The electromagnetic wave reflection device according to claim 1, characterized in that: The thickness of the conductive pattern is greater than or equal to 0.01 mm and less than or equal to 0.05 mm, and the occupancy rate of the conductive pattern relative to the dielectric layer is greater than or equal to 10.0% and less than or equal to 45.0%.

4. The electromagnetic wave reflection device according to claim 1, characterized in that: The invention also includes an intermediate layer covering the adhesive layer and the conductive pattern.

5. The electromagnetic wave reflection device according to claim 4, characterized in that: A dielectric substrate is also provided which is bonded onto the conductive pattern via the intermediate layer.

6. An electromagnetic wave reflecting fence, characterized in that: A plurality of electromagnetic wave reflecting devices according to any one of claims 1 to 5 are connected via the frame.

7. The electromagnetic wave reflecting fence according to claim 6, characterized in that: At least a portion of the reflective panel is a metasurface having different incident angles and reflection angles.

8. A reflective panel, which is a reflective panel used in an electromagnetic wave reflecting device, characterized in that: have: a dielectric layer; a periodic conductive pattern disposed on one surface of the dielectric layer; a ground layer disposed on the other surface of the dielectric layer; as well as an adhesive layer that bonds the conductive pattern to the one surface of the dielectric layer, The adhesive layer covers the entire surface of the one surface of the dielectric layer, In the range of 1 GHz to 30 GHz, the relative dielectric constant of the adhesive layer is 2.0 to 3.0 and the dielectric loss tangent is greater than 0.00 and less than 0.10, or the relative dielectric constant of the adhesive layer is 3.0 to 4.5 and the dielectric loss tangent is greater than 0.00 and less than 0.

02.

9. The reflective panel according to claim 8, characterized in that: At the frequency of 1 GHz to 30 GHz, the relative dielectric constant of the adhesive layer is 2.2 to 2.7, and the dielectric loss tangent is greater than 0.00 and is 0.09 to 0.09.

Images