JP2006229035A - Radio-wave shield material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio-wave shield material whose radio-wave shield factor is made high only to the radio-wave of a specific frequency. <P>SOLUTION: In the radio-wave shield material 1, a plurality of antennas 4 each of which reflects the radio wave of a specific frequency are so provided as to constitute a pattern. Each of the plurality of antennas 4 has three line-segment-form first elements 4a having nearly equal lengths to each other and so extended outward from the center of the antenna as to form an angle of 120° with each other and has three line-segment-form second elements 4b having nearly equal lengths to the first elements 4a the center of each of which is so coupled to each first element 4a at its outside end as to make each second element 4b orthogonal to each first element 4a. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a radio wave shield.

  In recent years, it has become indispensable to prepare the radio environment in the office from the viewpoint of preventing information leakage and malfunction and noise due to intruding radio waves from the outside, while the use of PHS and wireless LAN in offices is spreading. . Various types of members for maintenance of such a radio wave environment have been proposed (for example, Patent Documents 1 and 2).

  Patent Document 1 discloses an electromagnetic shield / intellect building that can communicate information using radio waves of an arbitrary frequency in a wide frequency band by adding an electromagnetic shield member such as metal or ferrite to a building frame. Yes. In Patent Document 1, a radio wave reflector such as an iron plate, a metal net, a metal mesh, or a metal foil or a radio wave absorber such as ferrite is used as a radio wave shield member. However, these radio wave reflectors and radio wave absorbers do not have frequency selectivity in electromagnetic shielding properties. For this reason, the electromagnetic shield intelligent building disclosed in Patent Document 1 cannot selectively shield only radio waves of a specific frequency, and has a problem of shielding even radio waves other than the frequency to be shielded. .

Further, in Patent Document 2, an electromagnetic shielding surface is formed by periodically arranging “Y” -shaped linear antennas, and an electromagnetic shielding space is secured in a building by the electromagnetic shielding surface. Shielded buildings are disclosed. The “Y” -shaped linear antenna includes three line-shaped element portions extending outward from the center of the antenna. According to the electromagnetic shielding building disclosed in Patent Document 2, it is described that only a radio wave having a necessary frequency can be selected and electromagnetic shielding can be performed.
Japanese Patent Publication No. 6-99972 JP-A-10-169039

  In the electromagnetic shielding building described in Patent Document 2, the linear antenna that reflects radio waves is formed in a “Y” shape. In order to reflect radio waves of a specific frequency more reliably, it is preferable to arrange linear antennas on the electromagnetic shielding surface efficiently and with high density. However, it is difficult for the “Y” -shaped linear antenna disclosed in Patent Document 2 to be efficiently and densely arranged (many linear antennas per unit area).

  In order to realize high radio wave shielding, it is particularly preferable to arrange the element portions so as to face each other closely. However, in the “Y” -shaped linear antenna disclosed in Patent Document 2, it is difficult to dispose the element portions so as to face each other substantially in parallel.

  For this reason, in the electromagnetic shielding building described in patent document 2, there exists a problem that it is difficult to fully shield only the electromagnetic wave of a specific frequency.

  In addition, since the conventional radio wave shield has a large bandwidth of 10 dB with respect to the center frequency, it also shields radio waves other than the target specific frequency. For this reason, there also exists a problem that the electromagnetic wave environment with respect to electromagnetic waves other than a specific frequency will be deteriorated.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a radio wave shielding body having a high radio wave shielding rate against only radio waves of a specific frequency.

  In the radio wave shielding body according to the present invention, a plurality of antennas each reflecting a radio wave of a specific frequency are provided so as to form a pattern. Each of the plurality of antennas includes three first element portions having substantially the same length extending outward (radially extending) from the antenna center at an angle of 120 ° to each other, and three Each outer end of the first element portion has a line-shaped second element portion having the same length as the first element portion, the center of which is coupled to be orthogonal to the first element portion.

  The radio wave shield according to the present invention includes a plurality of antennas provided so as to form a pattern. The lengths of the first element portion and the second element portion constituting the antenna are appropriately determined according to the frequency of the radio wave to be reflected, and each of the plurality of antennas selectively reflects the radio wave of a specific frequency. For this reason, the radio wave of a specific frequency incident on the radio wave shield according to the present invention is shielded by the antenna. On the other hand, radio waves having frequencies other than the specific frequency are not reflected (shielded) by the antenna. Therefore, the radio wave shielding body according to the present invention can selectively shield radio waves having a specific frequency among incident radio waves and transmit radio waves having a frequency other than the specific frequency. In other words, the radio wave shield according to the present invention has frequency selectivity.

  In the radio wave shield according to the present invention, the first element portion and the second element portion are formed to have substantially the same length. As described above, the lengths of the first element portion and the second element portion correlate with the frequency of the radio wave to be shielded (reflected). For this reason, the high frequency selectivity of a radio wave shielding body is realizable by making the 1st element part and the 2nd element part into substantially the same length.

  In the present invention, the plurality of antennas have a second element portion whose center is coupled so as to be orthogonal to the first element portion at the outer end of the first element portion. For this reason, the radio wave shielding body according to the present invention can easily realize a high radio wave shielding rate for only radio waves of a specific frequency. This is because each of the plurality of antennas has the second element portion, and thus it is relatively easy to arrange the plurality of antennas so that the second element portions face each other.

  The present inventors can improve the radio wave shielding rate against radio waves of a specific frequency by arranging a plurality of antennas so that the second element portions are opposed (more preferably, closely opposed). As a result of sincerity research, it was found for the first time.

  In the radio wave shielding body according to the present invention, the plurality of antennas may constitute an antenna unit by a pair arranged so that the second element portions face each other. By arranging the plurality of antennas so that the second element portions face each other, it is possible to increase the radio wave reflectance of the antenna with respect to a radio wave having a specific frequency. Therefore, according to this configuration, it is possible to realize a high radio wave shielding rate for only radio waves having a specific frequency. From the viewpoint of realizing a higher radio wave shielding rate for radio waves of a specific frequency, it is preferable that the interval between the opposing second element portions is small.

  Further, the plurality of antennas may constitute a substantially regular hexagonal pattern in which the antenna unit is further arranged with the second element portions facing each other and continuously developed two-dimensionally. In other words, six antennas (three antenna units) may be arranged in a ring shape so that the second element portions face each other. In this configuration, the figure formed by connecting the antenna centers of the six antennas arranged in a ring form a substantially regular hexagon.

  In order to increase the radio wave shielding rate (radio wave reflectivity) for radio waves having a specific frequency by the antenna, it is preferable to increase the number of second element portions arranged so as to face each other. According to this configuration, it is possible to increase the number of second antennas facing the second element part of another antenna among the three second element parts included in one antenna. For this reason, the radio wave reflectance with respect to the radio wave of the specific frequency of an antenna can be made higher. Therefore, according to this configuration, it is possible to realize a higher radio wave shielding rate for radio waves of a specific frequency.

  In the radio wave shield according to the present invention, the plurality of antennas include a conductive material. The radio wave reflectivity of the antenna with respect to a specific frequency wave correlates with the conductivity of the antenna. The higher the conductivity of the antenna (the smaller the electric resistance of the antenna), the higher the radio wave reflectance of the antenna with respect to radio waves of a specific frequency. For this reason, the radio wave reflectance with respect to the radio wave of the specific frequency of an antenna can be enlarged by improving the electroconductivity of an antenna. Therefore, according to this configuration, it is possible to realize a high radio wave shielding rate for only radio waves having a specific frequency.

  Examples of the conductive material include aluminum, silver, copper, gold, platinum, iron, carbon, graphite, indium tin oxide (ITO), a mixture or an alloy thereof. Among them, since aluminum and silver are relatively inexpensive, the antenna preferably includes at least one of aluminum and silver.

  As described above, according to the present invention, it is possible to realize a radio wave shield that can shield radio waves of a specific frequency with a high radio wave shielding rate.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  (Embodiment 1) FIG. 1 is a sectional view of a radio wave shield 1 according to Embodiment 1. FIG. Specifically, the diagram shown in FIG. 1B is a cross-sectional view of a portion cut out along a cut line Ia-Ia in the plan view of the radio wave shield 1 shown in FIG.

  FIG. 2 is a plan view of the radio wave shield 1.

  FIG. 3 is a plan view showing the configuration of the antenna 4.

  The radio wave shield 1 includes a base material 2 and a reflective layer 3 formed on the surface of the base material 2. The material of the base material 2 is not limited at all, and can be appropriately selected according to the intended use of the radio wave shield 1. In the first embodiment, the radio wave shield 1 is an aspect in which the reflective layer 3 is formed on the surface of the base material 2, but the reflective layer 3 may be embedded in the base material.

  The base material 2 can be appropriately selected according to the intended use of the radio wave shield 1 as described above. Among them, the radio wave shielding body 1 according to the present invention includes a mode in which radio wave shielding characteristics are provided to existing indoor objects (for example, windows, walls, ceilings, floors, partitions, desks, etc.). For this reason, as a material of the base material 2, resin, glass, paper, rubber, gypsum, tile, wood, etc. are preferable.

  The substrate 2 is preferably in a shape having a flat surface such as a plate shape, a sheet shape, or a film shape.

  In addition, the base material 2 has not only a role as a base material but also a role of various properties (translucency, nonflammability, flame retardancy, non-halogenity, flexibility, impact resistance, heat resistance, etc.). It is particularly preferable that

  For example, when the radio wave shield 1 is light transmissive, the substrate 2 needs to be made of a transparent (light transmissive) material. For this reason, as a material of the base material 2, transparent glass (for example, soda lime, quartz, etc. can be applied. Among them, soda lime is preferable in terms of cost) and a transparent polymer are exemplified. Among them, a transparent polymer is preferable as the material of the substrate 2 in that it can be thinly formed, is flexible and can be wound (can be rolled) (hereinafter, transparent). A film formed of a polymer is referred to as a “transparent polymer film”).

  Specific materials for the transparent polymer film include, for example, polyethylene terephthalate, polyethersulfone, polystyrene, polyethylene naphthalate, polyarylate, polyetheretherketone, polycarbonate, polyethylene, polypropylene, nylon 6 and other polyamides, polyimides, Cellulosic resins such as acetyl cellulose, fluorine resins such as polyurethane and polytetrafluoroethylene, vinyl compounds such as polyvinyl chloride, polyacrylic acid, polyacrylate esters, polyacrylonitrile, addition polymers of vinyl compounds, polymethacrylic acid , Vinylidene compounds such as polymethacrylic acid ester and polyvinylidene chloride, vinyl compounds such as vinylidene fluoride / trifluoroethylene copolymer, ethylene / vinyl acetate copolymer, etc. Or copolymers of fluorine-based compound, polyether such as polyethylene oxide, epoxy resins, polyvinyl alcohol, polyvinyl butyral, and the like. The thickness of the transparent polymer film used for the radio wave shield 1 is usually 10 μm or more and 500 μm or less. The thickness of a preferable transparent polymer film is 30 μm or more and 150 μm or less. A more preferable thickness of the transparent polymer film is 50 μm or more and 120 μm or less. If the transparent polymer film is as thin as 10 μm, formation of the reflective layer 3 tends to be difficult, and if it is thicker than 500 μm, the flexibility tends to decrease and the winding tends to be difficult (it is difficult to roll). Moreover, when the transparent polymer film is thicker than 500 μm, the translucency tends to decrease.

  Furthermore, since the radio wave shield 1 produced by forming the reflective layer 3 on the surface of the substrate 2 is provided on an existing object in the room (for example, a window, a wall, a ceiling, a floor, a partition, a desk, etc.) Apply a pressure-sensitive adhesive or an adhesive to at least one of the surface on the side where the layer 3 is formed and the surface on the opposite side, roll a protective layer on the surface of the adhesive or the pressure-sensitive adhesive (in the form of toilet paper) It may be an embodiment that can be rolled and cut according to the required length.

  4 to 7 illustrate product patterns (usage status) of the radio wave shield 1 according to the first embodiment.

  FIG. 4 is a cross-sectional view when the base material 2 side of the radio wave shield 1 is adhered to glass (window glass) 7. In FIG. 4, the radio wave shield 1 is adhered to the glass 7 by an adhesive 8 provided on the base material 2 side of the radio wave shield 1.

  FIG. 5 is a schematic diagram of the radio wave shield 1 in which the adhesive 8 and the protective film 9 are formed on the base material 2 side of the radio wave shield 1 and rolled into a toilet paper shape. In the case of the radio wave shield 1 shown in FIG. 5, it can be used by cutting it according to the required length, peeling off the protective film 9 and adhering it to glass or the like.

  FIG. 6 is a cross-sectional view when the reflection layer 3 side of the radio wave shield 1 is adhered to the glass (window glass) 7. In FIG. 6, the radio wave shield 1 is adhered to the glass 7 by an adhesive 8 provided on the reflection layer 3 side of the radio wave shield 1.

  FIG. 7 is a schematic diagram of the radio wave shield 1 in which the pressure-sensitive adhesive 8 and the protective film 9 are formed on the reflection layer 3 side of the radio wave shield 1 and rolled in the form of toilet paper. In the case of the radio wave shield 1 shown in FIG. 7, it can be used by cutting it according to the required length, removing the protective film 9 and adhering it to glass or the like.

  The reflective layer 3 formed on the substrate 2 is composed of a plurality of antennas 4 arranged in a predetermined pattern so as to form a pattern. In the radio wave shield 1 according to the first embodiment, the reflective layer 3 is configured only by a plurality of antennas 4 patterned in the same shape, but the present invention is not limited to this configuration at all. The reflective layer 3 may include a pattern having a shape different from that of the antenna 4 in a part thereof.

  The plurality of antennas 4 are arranged in a matrix on the substrate 2 at equal intervals. The plurality of antennas are arranged so that adjacent antennas do not contact each other. As shown in FIG. 3, each of the plurality of antennas 4 has three first element portions 4a and three second element portions 4b. The three first element portions 4a extend outward from the antenna center C at an angle of 120 ° to each other. The center of the second element portion 4b is coupled to the outer end of the first element portion 4a so as to be orthogonal to the first element portion 4a. The 1st element part 4a and the 2nd element part 4b are each formed in the line segment shape of substantially the same length. In the present specification, the lengths of the first element portion 4a and the second element portion 4b are substantially the same L1.

  As will be described in detail later, the length of the first element portion 4a and the length of the second element portion 4b correlate with the frequency of the radio wave reflected by the antenna 4. For this reason, as in the first embodiment, by making the lengths of the first element portion 4a and the second element portion 4b substantially the same as L1, the specific frequency is selected more selectively and the radio wave reflection is higher. Can be reflected at a rate. That is, by making the lengths of the first element portion 4a and the second element portion 4b substantially the same, it is possible to realize the radio wave shield 1 that is excellent in frequency selectivity and excellent in radio wave shielding properties at a specific frequency. . Further, from the viewpoint of realizing higher frequency selectivity, the difference in length between the first element portion 4a and the second element portion 4b is preferably 5% or less of the length of the first element portion 4a.

  The first element part 4a and the second element part 4b have substantially the same width. The difference in width between the first element portion 4a and the second element portion 4b is preferably 5% or less of the width of the first element portion 4a. In the present specification, the widths of the first element portion 4a and the second element portion 4b are substantially the same L2. The width L2 is preferably 0.3 mm or more and 2 mm or less. As will be described in detail later, the frequency selectivity of the antenna 4 can be increased as the width L2 is reduced. If the width L2 is larger than 2 mm, a desired frequency selectivity cannot be obtained. On the other hand, if the width L2 is smaller than 0.3 mm, manufacturing becomes difficult.

  The antenna 4 is made of a conductive material. The radio wave reflectance of the antenna 4 with respect to the radio wave having a specific frequency is attributed to the conductivity of the antenna 4. The higher the conductivity of the antenna 4 (the smaller the electric resistance of the antenna 4), the higher the radio wave reflectance of the antenna 4 with respect to radio waves of a specific frequency. For this reason, by increasing the conductivity of the antenna 4, it is possible to increase the radio wave reflectance of the antenna 4 with respect to radio waves of a specific frequency. Therefore, according to this configuration, it is possible to realize a high radio wave shielding rate for only radio waves having a specific frequency.

  Examples of the conductive material include aluminum, silver, copper, gold, platinum, iron, carbon, graphite, indium tin oxide (ITO), a mixture or an alloy thereof. The conductive material may contain at least one of aluminum and silver. Since aluminum and silver have relatively low electrical resistance among conductive materials and are inexpensive, the radio wave shield 1 having low radio wave shielding properties and high radio wave shielding properties by including at least one of aluminum and silver in the antenna 4. Can be realized. Among the conductive materials, silver is particularly preferable.

  The antenna 4 may include a fine particle of a conductive material such as aluminum or silver. For example, it is produced by forming a paste containing a powdered conductive material in a binder (hereinafter sometimes referred to as “conductive paste”) uniformly in a predetermined pattern on the substrate 2 and then drying it. Can do. The conductive paste for producing the antenna 4 may be a powdered conductive material (for example, silver) dispersed in a polyester resin. In this case, the content of the conductive material is preferably 40% by weight or more and 80% by weight or less. As for the content rate of an electroconductive material, it is more preferable that they are 50 weight% or more and 70 weight% or less. If the content of the conductive material is less than 40 weight percent, it tends to be difficult to obtain sufficient conductivity of the antenna 4. On the other hand, when the content of the conductive material is more than 80 weight percent, it is difficult to uniformly disperse the resin in the resin. The polyester resin serves as an adhesive for bonding the conductive material and the base material.

  After forming the paste in a predetermined pattern, the antenna 4 can be manufactured by drying for 10 minutes to 5 hours in an atmosphere of 100 ° C. or more and 200 ° C. or less, for example. The thickness of the antenna 4 produced by such a method is preferably 10 μm or more and 20 μm or less. If the thickness of the antenna 4 is smaller than 10 μm, the conductivity of the antenna 4 tends to be lowered. When the thickness of the antenna 4 is larger than 20 μm, the pattern formability tends to be lowered.

  In the present invention, the method of forming the antenna 4 is not limited to this method, and the antenna 4 may be formed by other methods. For example, when the antenna 4 made of aluminum is formed, the substrate 2 is formed by a known film formation method such as a vapor deposition method, a sputtering method, or a chemical vapor deposition method (CVD method), and a known patterning such as photolithography. The antenna 4 can be formed by patterning into a predetermined pattern by a method. The antenna 4 may be formed by adhering or sticking a thin film of aluminum or the like patterned into a predetermined shape to the substrate 2. In addition, the antenna 4 can be formed by a silk printing method, a pattern pressure bonding method, an embedding method by fitting a mold, or the like.

  Hereinafter, radio wave reflection characteristics (radio wave shielding characteristics) of the radio wave shield 1 will be described in detail with reference to the drawings.

  FIG. 8 is a graph showing the relationship between the frequency of radio waves and the amount of transmission attenuation of radio waves when passing through the radio wave shield 1.

  In FIG. 8, L1 is 10.6 mm and L2 is 0.7 mm.

  As shown in FIG. 8, only the radio wave having a frequency near a specific frequency (about 2.7 GHz) among the radio waves incident on the radio wave shield 1 is attenuated by the radio wave shield 1. In other words, the radio wave shield 1 selectively blocks radio waves having a frequency near a specific frequency among the radio waves incident on the radio wave shield 1. This is because the reflection layer 3 of the radio wave shield 1, specifically each of the plurality of antennas 4 included in the reflection layer 3, selectively reflects radio waves having a frequency near a specific frequency. The frequency of the radio wave reflected by the antenna 4 is determined by the length (element length) L1 between the first element portion 4a and the second element portion 4b.

  FIG. 9 is a graph showing the relationship between L1 and the frequency of the radio wave reflected by the antenna 4.

  As shown in FIG. 9, the longer the L1 is, the lower the frequency of the radio wave reflected by the antenna 4 is. In other words, the frequency of the radio wave reflected by the antenna 4 increases as L1 increases. On the other hand, the frequency of the reflected radio wave is not greatly correlated with the width L2. That is, the frequency of the reflected radio wave mainly depends on L1. Therefore, L1 can be calculated from the frequency of the radio wave desired to be reflected based on the relationship between L1 and the selected frequency as shown in FIG. For example, when creating the radio wave shield 1 that shields radio waves with a frequency of 5 GHz, L1 may be about 0.5 mm.

  The size and shape of the radio wave shield 1 are not limited at all. The length of one side may be as small as several millimeters square, or one side may be as large as several meters or more. The radio wave shield 1 may be formed in an arbitrary shape such as a triangle, a quadrilateral (rectangle, square), a polygon, a circle, or an ellipse.

  Further, the number of antennas 4 included per unit area of the radio wave shield 1 is not limited at all, and can be appropriately changed depending on the application. By increasing the number of antennas 4 included per unit area of the radio wave shield 1, high radio wave shielding can be realized.

  The antenna 4 has a second element portion 4b having a center coupled to the outer end of the first element portion 4a so as to be orthogonal to the first element portion 4a. For this reason, it is relatively easy to arrange the plurality of antennas 4 so that the second element portions 4b face each other. Therefore, the radio wave shielding body according to the present invention can easily realize a high radio wave shielding rate only for radio waves of a specific frequency. Note that it is possible to improve the radio wave shielding rate against radio waves of a specific frequency by arranging a plurality of antennas 4 so that the second element portions 4b face each other (more preferably, closely face each other). As a result of sincerity research by the inventors, it was discovered for the first time. Hereinafter, another embodiment in which a plurality of antennas 4 are arranged so that the second element portions 4b face each other will be described in detail with reference to the drawings.

(Embodiment 2)
FIG. 10 is a plan view of the radio wave shield 10 according to the second embodiment.

  FIG. 11 is an enlarged plan view of a part of the radio wave shield 10.

  Similarly to the radio wave shield 1 according to the first embodiment, the radio wave shield 10 according to the second embodiment includes a base material 2 and a reflective layer 3 formed on the surface of the base material 2. The reflective layer 3 includes a plurality of antennas 4. Each of the plurality of antennas 4 has the same shape as that of the first embodiment (see FIG. 3). In the above points, the radio wave shield 10 according to the second embodiment has the same form as the radio wave shield 1 according to the first embodiment. The radio wave shield 10 according to the second embodiment is different from the radio wave shield 1 according to the first embodiment in the arrangement of the antennas 4 in the reflective layer 3. Hereinafter, the arrangement of the antennas 4 in the reflective layer 3 will be described in detail with reference to FIG.

  In the second embodiment, the plurality of antennas 4 constitute an antenna unit 5a by a pair arranged so that the second element portions 4b face each other. Further, the antenna unit 5a is arranged so that the second element portions 4b are opposed to each other, and constitutes a substantially regular hexagonal pattern that is continuously developed in two dimensions. In the radio wave shield 10, the antenna assemblies 5 including the three antenna units 5 a constituting the substantially regular hexagonal pattern are provided in a matrix. In other words, the antenna assembly 5 is composed of six antennas 4 that are arranged in a substantially annular shape with the second element portions 4b facing each other.

  In the second embodiment, 12 of the 18 second element portions 4b constituting the antenna assembly 5 are provided so as to face each other substantially in parallel. In this way, by configuring so that many second element portions 4b face each other, it is possible to increase only the radio wave reflectance (radio wave shielding rate) of the antenna 4 with respect to radio waves of a specific frequency. Therefore, it is possible to realize the radio wave shield 10 having a high radio wave shielding rate for only radio waves of a specific frequency. In addition, the radio wave reflectance of the radio wave shield 10 increases as the distance between the second element portions 4b facing each other is shortened. Specifically, the distance X (see FIG. 11) between the opposing second element portions 4b is preferably 0.4 mm or more and 3 mm or less. A more preferable range is 0.6 mm or more and 1 mm or less. If the distance X is shorter than 0.4 mm, the opposing second element parts 4b may come into contact undesirably. On the other hand, if the distance X is longer than 3 mm, it is difficult to achieve a desired radio wave shielding rate.

(Embodiment 3)
FIG. 12 is a plan view of the radio wave shield 20 according to the third embodiment.

  The radio wave shielding body 20 according to the third embodiment is similar to the radio wave shielding body 1 according to the first embodiment and the radio wave shielding body 10 according to the second embodiment, and the reflection layer formed on the surface of the base material 2. 3. The reflective layer 3 includes a plurality of antennas 4. Each of the plurality of antennas 4 has the same shape as that of the first embodiment (see FIG. 3). In the above points, the radio wave shield 20 according to the third embodiment has the same form as the radio wave shield 1 according to the first embodiment and the radio wave shield 10 according to the second embodiment. The radio wave shield 20 according to the third embodiment is different from the radio wave shield 1 according to the first embodiment and the radio wave shield 10 according to the second embodiment in the arrangement of the antennas 4 in the reflective layer 3. Hereinafter, the arrangement of the antennas 4 in the reflective layer 3 will be described in detail with reference to FIG.

  In the third embodiment, the plurality of antennas 4 constitute an antenna unit 5a by a pair arranged so that the second element portions 4b face each other. Further, the antenna unit 5a is arranged so that the second element portions 4b are opposed to each other, and constitutes a substantially regular hexagonal pattern that is continuously developed in two dimensions. In the radio wave shield 20, the three antenna units 5 a constituting the substantially regular hexagonal pattern constitute the antenna assembly 5. In Embodiment 3, the antenna assembly 5 is further arranged so that the second element portions 4b face each other. In the third embodiment, a plurality of antennas 4 are arranged so that almost all the second element portions 4b face each other.

  As described above, the radio wave shielding body 20 having a higher radio wave reflectivity can be realized by further increasing the number of the second element portions 4b provided to face each other as compared with the second embodiment. .

  By the way, in the present situation where the operating frequency band is becoming saturated, it is necessary to improve the radio wave environment with sufficient consideration of frequency selectivity. Since the radio wave shield 20 according to the present invention has a very high frequency selectivity, it is suitable for maintenance of the radio wave environment.

  FIG. 13 is a graph showing the radio wave shielding characteristics of the radio wave shield 20 according to the third embodiment.

  As shown in FIG. 13, the 10 dB bandwidth [(F2−F1) / F0 (%)] of the radio wave shield 20 according to the third embodiment is as very small as 10.4. Thus, the radio wave shield 20 has very high frequency selectivity.

  In contrast, conventional radio wave shields do not have sufficient frequency selectivity.

  FIG. 14 is a plan view of a conventional radio wave shield 100.

  FIG. 15 is a graph showing the radio wave shielding characteristics of the radio wave shield 100.

  FIG. 16 is a plan view of a conventional radio wave shield 200.

  FIG. 17 is a graph showing the radio wave shielding characteristics of the radio wave shield 200.

  The conventional radio wave shield 100 is made of a plurality of so-called “Jerusalem cross-type” antennas. The 10 dB bandwidth [(F2-F1) / F0 (%)] with respect to the center frequency (F0) of the radio wave shield 100 is 17.0, as shown in FIG. 15, and the radio wave shield 20 according to the third exemplary embodiment. Is much larger than that. Further, the 10 dB bandwidth [(F2-F1) / F0 (%)] of the conventional radio wave shield 200 shown in FIG. 16 is 33.0, as shown in FIG. 17, and the radio wave shield according to the third embodiment. It will be much larger than 20. As described above, the conventional radio wave shields 100 and 200 with low frequency selectivity shield radio waves other than the target specific frequency (range), and deteriorate the radio wave environment for radio waves other than the specific frequency.

  As described above, since the radio wave shield 20 according to the present invention has a small 10 dB bandwidth, it has high radio wave selectivity. Therefore, according to the radio wave shield 20 according to the present invention, it is possible to suitably shield only a radio wave having a target specific frequency.

  The center frequency (F0) is different between the radio wave shield 20 according to the present invention and the conventional radio wave shields 100 and 200. However, the 10 dB bandwidth does not depend on the center frequency.

(Embodiment 4)
In the first to third embodiments, the radio wave shield has been described as an application example of the present invention. However, the radio wave shielding body according to the present invention is not limited to the above-described embodiment. For example, the reflection layer 3 including a plurality of antennas 4 may be provided inside the radio wave shielding body. In the fourth embodiment, a radio wave shield in which a reflective layer 3 including a plurality of antennas 4 is provided will be described with reference to the drawings.

  FIG. 18 is a cross-sectional view illustrating a configuration of a radio wave shield (radio wave shield plate) 30 according to the fourth embodiment.

  The radio wave shielding plate 30 according to the fourth embodiment has a configuration in which the radio wave shielding body 1 according to the first embodiment (or the second and third embodiments) is laminated on the plate-like body 6. The plate-like body 6 is not limited at all, but is, for example, a wooden plate, a glass plate, or the like. The radio wave shield 1 is adhered or bonded to the plate-like body 6 with an adhesive 8. As an adhesive, an acrylic adhesive etc. are preferable from a transparency viewpoint. Examples of the adhesive include acrylic adhesives. The layer thickness of the pressure-sensitive adhesive or adhesive is preferably 10 μm or more and 60 μm or less from the viewpoint of adhesion (adhesion) property, radio wave shielding property, and transparency. A more preferable range is 20 μm or more and 50 μm or less.

  Even when the radio wave shield 1 is adhered or adhered to a plate-like body 6 such as glass via an adhesive or a pressure sensitive adhesive as in the fourth embodiment, the antenna 4 has a specific frequency radio wave. Can be selectively reflected (shielded). Therefore, also in the radio wave shielding plate 30 according to the fourth embodiment, it is possible to realize a high radio wave shielding rate for only radio waves of a specific frequency.

  However, the case where one surface of the antenna 4 is in contact with the atmosphere as in the first embodiment and the case where both surfaces of the antenna 4 are in contact with the substrate 2 or the plate-like body 6 as in the fourth embodiment. Therefore, even if the shape and material of the antenna 4 are the same, the frequency of the radio wave reflected (shielded) by the antenna 4 is different.

  FIG. 19 is a graph showing the resonance frequency of the radio wave shield 1 in a state where it is not adhered to the glass plate 6.

  FIG. 20 is a graph showing the resonance frequency of the radio wave shield 1 with the reflective layer 3 side adhered to the glass plate-like body 6.

  The relational expressions shown in FIGS. 19 and 20 are regression equations of the obtained resonance frequency data.

  As shown in FIGS. 19 and 20, when the reflection layer 3 side of the radio wave shield 1 is adhered to the glass plate-like body 6, the relationship between the element length and the resonance frequency changes. Specifically, when the reflection layer 3 side of the radio wave shield 1 is adhered to the glass plate 6, the frequency of the radio wave reflected (shielded) by the antenna 4 becomes low. The amount of change in the frequency of radio waves is not greatly affected by the layer thickness of the plate-like body 6 to which the radio wave shield 1 is adhered. In particular, in the range where the layer thickness of the plate-like body 6 is 2 mm or more and 20 mm or less, the relational expression shown in FIG. 20 hardly changes.

  As described above, the radio wave shielding body according to the present invention has a high radio wave shielding rate only for radio waves of a specific frequency, and includes wallpaper, partitions (partitions), window glass, outer wall panels, roof boards, ceiling boards, and inner wall panels. It is useful as a floor board, a radio wave shield, etc.

1 is a cross-sectional view of a radio wave shield 1 according to Embodiment 1. FIG. 2 is a plan view of the radio wave shield 1. FIG. 2 is a plan view illustrating a configuration of an antenna 4. FIG. It is sectional drawing at the time of adhere | attaching the base material 2 side of the electromagnetic wave shielding body 1 on the glass (window glass) 7. FIG. It is a schematic diagram of the radio wave shield 1 in which an adhesive 8 and a protective film 9 are formed on the base material 2 side of the radio wave shield 1 and rolled into a toilet paper shape. It is sectional drawing at the time of sticking the reflective layer 3 side of the radio wave shielding body 1 to the glass (window glass) 7. It is a schematic diagram of the radio wave shield 1 in which an adhesive 8 and a protective film 9 are formed on the reflection layer 3 side of the radio wave shield 1 and rolled into a toilet paper shape. 4 is a graph showing the relationship between the frequency of a radio wave and the transmission attenuation of the radio wave when transmitted through the radio wave shield 1. It is a graph showing the relationship between L1 and the frequency of the electromagnetic wave reflected by the antenna 4. 6 is a plan view of a radio wave shield 10 according to Embodiment 2. FIG. 3 is an enlarged plan view of a part of the radio wave shield 10. FIG. 6 is a plan view of a radio wave shield 20 according to Embodiment 3. FIG. It is a graph which shows the electromagnetic wave shielding characteristic of the electromagnetic wave shielding body 20 which concerns on this Embodiment 3. FIG. It is a top view of the conventional electromagnetic wave shield 100. 3 is a graph showing radio wave shielding characteristics of the radio wave shield 100. It is a top view of the conventional electromagnetic wave shield 200. 5 is a graph showing radio wave shielding characteristics of the radio wave shield 200. 6 is a cross-sectional view illustrating a configuration of a radio wave shield (radio wave shielding plate) 30 according to Embodiment 4. FIG. It is a graph which shows the resonant frequency of the electromagnetic wave shield 1 of the state which is not made to adhere to the plate-shaped body 6 made from glass. It is a graph which shows the resonant frequency of the radio wave shielding body 1 in the state where the reflective layer 3 side is adhered to the glass plate-like body 6.

Explanation of symbols

1, 10, 20 Radio wave shield
2 Base material
3 Reflective layer
4 Antenna
4a 1st element part
4b Second element part
5 Antenna assembly
5a Antenna unit
6 Plate
7 Glass
8 Adhesive
9 Protective film
30 radio wave shielding plate

Claims (5)

Each is a radio wave shield provided so that a plurality of antennas that reflect radio waves of a specific frequency constitute a pattern,
Each of the plurality of antennas is
Three first element portions having substantially the same length and extending outward from the center of the antenna at an angle of 120 ° to each other;
A line-shaped second element having a length substantially the same as the first element portion, the center of which is coupled to the outer end of each of the three first element portions so as to be orthogonal to the first element portion. And
A radio wave shield having: The radio wave shield according to claim 1,
The plurality of antennas are radio wave shielding bodies that constitute an antenna unit by a pair of antenna elements arranged so that the second element portions face each other. The radio wave shield according to claim 2,
The plurality of antennas are radio wave shields that form a substantially regular hexagonal pattern in which the antenna unit is further arranged so that the second element portions are opposed to each other and continuously developed in two dimensions. The radio wave shield according to claim 1,
A radio wave shield in which the plurality of antennas include a conductive material. In the radio wave shield according to claim 4,
A radio wave shield in which the conductive material contains at least one of aluminum and silver.

Images