JP2009239211A - Radiowave absorption sheet and method of installing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate operations to install and maintain a radiowave absorption sheet which is installed at a circumference of a nearly-circularly-sectioned long structure 60 of a DSRC (Dedicated Short Range Communication) system such as an ETC system to cover the long structure 60. <P>SOLUTION: The radiowave absorption sheet 10 comprises: a sheet body 30 which has flexibility and absorbs a radiowave of prescribed frequency; and a holder 20 which holds the sheet body 30 in a curved section state. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a radio wave absorbing sheet that is installed around a long structure such as a canopy post of a toll booth in an ETC (Electronic Toll Collection) system so as to cover the long structure, and in particular, the installation work is easy. It relates to measures to become.

  For example, in a toll gate in an ETC system, in order to prevent radio waves emitted from a roadside device from being diffusely reflected by surrounding structures, a powdery loss material is used as a binder such as a resin as described in Japanese Patent Laid-Open No. 2004-228620. A radio wave absorber having a radio wave absorption layer solidified by (1) and a radio wave reflection layer laminated on one surface thereof is installed on the surface of the structure so as to cover the surface.

  In that case, when covering the lower surface of the canopy etc. which are arrange | positioned above the booth of a toll booth in planar shape, as described in patent document 2, a radio wave absorption board is used.

  And when covering long structures, such as a round pipe-like support | pillar of a canopy, in a curved surface shape, as described in patent document 3, it is comparatively thin (for example, about 2 mm) so that it can be bent easily. A flexible radio wave absorbing sheet is used, and such a radio wave absorbing sheet is installed so as to surround a long structure.

As a specific installation method of the radio wave absorbing sheet, a base material is installed around the long structure so as to cover the long structure, and the radio wave absorbing sheet is adhered on the base material, or When the cross-sectional shape of the long structure is a smooth curved surface, the base material is not used, and the radio wave absorbing sheet is directly attached to the surface of the long structure.
JP 2004-146611 A (pages 3 to 5, FIG. 1) Japanese Patent Application Laid-Open No. 11-044018 (pages 2, 3 and 1) JP 2003-234593 A (3rd and 4th pages, FIG. 1)

  By the way, even if it has flexibility, even if it has flexibility, since a waist is quite strong, there is a problem that it is difficult to install it in a curved shape with good appearance and requires skill.

  Moreover, when sticking directly to a long structure, there also exists a problem that maintenance property is not good.

  The present invention has been made in view of these points, and its main purpose is to be installed around a long structure in a DSRC (Dedicated Short Range Communication) system such as an ETC system. An object of the present invention is to avoid the trouble of installation work and maintenance work for the radio wave absorbing sheet.

  In order to achieve the above object, in the present invention, the radio wave absorption sheet is bent in a cross-sectional shape in advance and held by a holding body, and is installed around a long structure.

  Specifically, the present invention is premised on a radio wave absorbing sheet that is installed around a long structure so as to cover the long structure.

  And it shall have the sheet | seat main body which has flexibility and absorbs the electromagnetic wave of a predetermined frequency, and the holding body holding this sheet | seat main body in a cross-sectional curved shape.

  In the above configuration, the holding body is formed by dividing a tubular material that can surround at least a part of the lengthwise structure in the length direction into a plurality of parts in the circumferential direction. The holder can be held in a laminated state. In this case, the holding body may be formed by dividing the pipe material into two substantially equally in the circumferential direction.

  Further, the sheet main body may be adhered to the holding body with an adhesive (for example, elastic mastic adhesive) or may be secured to the holding body with a fastening tool (for example, a screw or a rivet). Also good.

  Further, the sheet main body includes a radio wave absorption layer that transmits and attenuates a part of the radio wave incident on one surface of the sheet main body, and the radio wave is positioned on the long structure side of the radio wave absorption layer. A radio wave reflection layer that is laminated on the absorption layer and reflects the part of the radio waves that have passed through the radio wave absorption layer can be provided.

  In addition, as a method of installing the radio wave absorption sheet having the above-described configuration, a plurality of radio wave absorption sheets are attached to the long structure, and the sheet main body of the plurality of radio wave absorption sheets is at least in the length direction of the long structure. It is possible to arrange a part of the plurality of radio wave absorption sheets so as to surround a part of the entire circumference, and then to bind the plurality of radio wave absorption sheets.

  In the present invention, the radio wave absorbing sheet is held in a curved shape in the cross section of the holding body, and the radio wave absorbing sheet thus configured is installed around the elongate structure so that the elongate structure is sheeted. Since it can be covered by the main body, it is not necessary to bend the electromagnetic wave absorbing sheet on the site and to bond the long structure to the long structure. Outside maintenance work can also be facilitated.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments according to the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a perspective view showing an overall configuration of a radio wave absorption sheet according to Embodiment 1 of the present invention. This radio wave absorption sheet 10 is a column with a circular cross section that supports a canopy above a booth in a toll booth of an ETC system. The support 60 is installed around the periphery of the support 60.

  In the present embodiment, the radio wave absorption sheet 10 includes a holding body 20 having a semicircular cross section, and a sheet body 30 laminated on the outer peripheral surface of the holding body 20 and held in a semicircular cross section. It is equipped with.

  Specifically, the holding body 20 is obtained by dividing a round pipe made of a relatively lightweight material into a radial direction along the length direction. It is slightly larger than the outer diameter. In addition, as a material of the said round pipe, it can employ | adopt suitably according to use conditions etc. from well-known things, such as stainless steel alloy, aluminum alloy, and a vinyl chloride resin.

  As shown in FIG. 2 in an enlarged manner, the sheet main body 30 has flexibility and absorbs radio waves having a predetermined frequency, and a part of the radio waves incident on the sheet main body 30 is absorbed. A radio wave absorption layer 31 that is attenuated while being transmitted, and is laminated on the radio wave absorption layer 31 so as to be positioned on the support 60 side (lower side in the figure) of the radio wave absorption layer 31, and transmits through the radio wave absorption layer 31. In addition to the radio wave reflection layer 32 that reflects the radio wave, the radio wave absorption layer 31 is laminated on the side opposite to the radio wave reflection layer 32 (upper side in the figure) and has a non-combustible layer 33 that transmits the radio wave.

  The basic composition of the radio wave absorption layer 31 is such that a powder of loss material such as carbonyl iron is bonded with a binder such as chlorinated polyethylene. The radio wave reflection layer 32 has a metal foil 32b such as an aluminum alloy foil supported on a carrier 32a such as a PET (Poly Ethylene Terephthalate) film, and is laminated so that the metal foil 32b is bonded to the radio wave absorption layer 31. Yes. The incombustible layer 33 is made of a decorative glass cloth having incombustibility. These three layers 31 to 33 are formed in a sheet shape by, for example, press thermocompression in a state where they are overlapped with each other. Moreover, in this embodiment, the sheet | seat main body 30 is affixed on the holding body 20 with adhesive agents, such as an elastic mastic adhesive agent.

  Next, an operation procedure for installing the radio wave absorbing sheet 10 configured as described above around the support column 60 so as to cover the support column 60 will be described.

  First, the two radio wave absorbing sheets 10 and 10 are arranged such that the holding body 20 of each radio wave absorbing sheet 10 faces the support column 60 and the two radio wave absorbing sheets 10 and 10 have a part in the length direction of the support column 60 all around. It arrange | positions in the state surrounded over. Thereafter, the two radio wave absorbing sheets 10 and 10 are bound together by using a binding band 40 such as a stainless steel band while holding the two radio wave absorbing sheets 10 and 10 in the above state. Specifically, for example, when the length dimension of the radio wave absorbing sheet 10 is about 1 m, it is preferable to bind at three or more locations per set of radio wave absorbing sheets 10 and 10. Accordingly, the two radio wave absorbing sheets 10 and 10 are installed so that the sheet main bodies 30 and 30 of the two radio wave absorbing sheets 10 and 10 cover a part of the column 60 in the length direction over the entire circumference. Can do. And the above operation | work is repeated over the required range of the length direction in the support | pillar 60, The installation operation | work of the electromagnetic wave absorption sheet | seat 10,10, ... with respect to the support | pillar 60 will be complete | finished. Note that the gap between the radio wave absorbing sheets 10 and 10 may be filled with, for example, a silicone sealing material to seal the gap.

  Therefore, in this embodiment, the inner diameter dimension of the electric wave absorbing sheets 10, 10,... Installed to surround the column 60 around the column 60 having a circular cross section supporting the canopy of the toll booth in the ETC system. In advance, a sheet body 30 is held in a semicircular cross section in a semicircular cross section holding body 20 in which a round pipe larger than the outer diameter dimension of 60 is halved in the length direction, The two wave absorbing sheets 10, 10 are combined and bundled so that a part of the length of the support 60 is surrounded by the entire circumference, and the wave absorbing sheets 10, 10,. Therefore, the installation work of the radio wave absorbing sheet 10 is facilitated as compared to the case where the radio wave absorbing sheet is bent at the site and adhered to the support column 60 with an adhesive as in the prior art. DOO can not only, at the time of maintenance may be removed wave absorbing sheet 10 applicable easily.

  In addition, in said embodiment, when enclosing a part in the length direction of the support | pillar 60 over the perimeter with the electromagnetic wave absorption sheet 10, the two electromagnetic wave absorption sheets 10 and 10 which each make a semicircular cross section are shown. Although used, three or more radio wave absorbing sheets 10, 10,... Each having a substantially arc shape in cross section may be used.

  In the above embodiment, the radio wave absorbing sheet 10 has a semicircular cross section, but the cross sectional shape is appropriately set according to the cross sectional shape and workability of the outer surface of the column 60. Can do.

  Further, in the above embodiment, the binding band 40 is used to bind the plurality of radio wave absorption sheets 10 arranged so as to surround a part of the support column 60 in the length direction over the entire circumference. However, other than the binding band 40, for example, a known binding tool such as a U bolt can be appropriately adopted and used.

  Furthermore, in said embodiment, the electromagnetic wave absorption sheet | seat 10 is installed in the support | pillar 60 with a circular cross section as an elongate structure which supports the canopy above the booth in the ETC system which absorbs the electromagnetic wave whose frequency is 5.8 GHz. Although the present invention is described, the present invention can be applied to a long structure other than the support column 60, and of course, can be applied to various long structures in a DSRC system using radio waves of various frequencies. Can also be applied.

(Embodiment 2)
FIG. 5 shows the overall configuration of the radio wave absorption sheet according to Embodiment 2 of the present invention, and this radio wave absorption sheet 10 is also installed on a canopy column 60 of a toll gate in the ETC system.

  In the present embodiment, the sheet main body 30 is fixed to the holding body 20 by the blind rivet 50 instead of being attached to the holding body 20 by an adhesive in the case of the first embodiment.

  Specifically, lower holes 30a and 20a are provided at both circumferential ends at a plurality of locations in the length direction of the sheet main body 30 (three locations in the illustrated example) and the corresponding portions of the holding body 20, respectively. It has been. Then, the blind rivet 50 is inserted into the lower holes 30a and 20a, and the tip end portion of the shaft portion bulges outward in the radial direction, so that the seat body 30 is fixed to the holding body 20. Since other parts are the same as those in the first embodiment, description thereof is omitted.

  Further, when the radio wave absorbing sheet 10 having the above configuration is installed on the support column 60, for example, the curvature radius r1 of the inner peripheral surface of the holding body 20 is larger (r1> r2) than the curvature radius r2 of the outer peripheral surface of the support column 60. If the installation state of the radio wave absorbing sheet 10 becomes unstable as it is, the thickness dimension T (> r1−) that can sufficiently fill the gap between the holding body 20 and the support column 60. A cushioning material 70 such as a rubber sheet having r2) is used in combination. Further, when the thickness T of the cushioning material 70 is too large and a circumferential gap is generated between the radio wave absorbing sheets 10 and 10, the gap is filled with, for example, a silicone sealing material 80. Seal.

  Therefore, the present embodiment can provide substantially the same effect as that of the first embodiment.

  In the above-described embodiment, only the blind rivet 50 is used. However, the blind rivet 50 and an adhesive may be used in combination. , Screws, etc.) can also be used.

  Here, an example of the sheet main body 30 that absorbs the 5.8 GHz radio wave used in the ETC system will be described.

  First, as a radio wave absorption layer sheet for constituting the radio wave absorption layer 31 of the sheet body 30, first, carbonyl iron is mixed with chlorinated polyethylene at a ratio of 38 vol%, and various additives are added as necessary. Mix and knead. The kneading operation is performed for 10 minutes to 1 hour while heating to 70 to 130 ° C. Then, it shape | molds in a sheet form with a well-known shaping | molding method (for example, roll rolling process etc.). At that time, the layer thickness t is set to t = 1.85 ± 0.03 [unit: mm]. Since the variation in the layer thickness sensitively affects the radio wave absorption characteristics, it is necessary to consider such a variation as much as possible. As an example of processing conditions in the case of roll rolling, the roll temperature h is set to h = 100 to 150 [unit: ° C.], and the pressure p is set to p = 0.1 to 2.0 [unit: MPa]. Is mentioned.

  The radio wave reflecting layer sheet for constituting the radio wave reflecting layer 32 of the sheet body 30 is supported by a PET film as a carrier 32a having a thickness dimension t = 25 [unit: μm], and the PET film. The one having the aluminum alloy foil as the metal foil 32b having the same thickness dimension t of t = 25 [μm] is used.

  “Coated glass K (trade name)”, which is a glass cloth manufactured by Unitika Glass Fiber Co., Ltd., is used for the incombustible layer sheet for constituting the incombustible layer 33 of the sheet body 30. This product is made of glass cloth coated on both sides with a vinyl chloride resin film, and is a non-combustible material (quasi-certified number: non-combustible (individual) 1445) as defined in Article 2, Item 9 of the Building Standards Act. ). The thickness dimension t is preferably t = 20 to 500 [unit: μm], more preferably t from the viewpoint of sufficiently exhibiting the radio wave absorption characteristics of the radio wave absorption layer 31 while ensuring nonflammability. = 20 to 100 [μm].

  And lamination | stacking integration of the sheet | seat for electric wave reflection layers and the sheet | seat for nonflammable layers with respect to said electromagnetic wave absorption layer sheet | seat is carried out by the thermocompression bonding which presses with the pressure of 0.1-2 MPa, for example, heating at 100-150 degreeC. You may make it carry out, and you may make it carry out by interposing an adhesive agent or only with an adhesive agent. In addition, lamination | stacking integration of the sheet | seat for radio wave reflection layers and the sheet | seat for nonflammable layers may be performed simultaneously, and may be performed in order.

  Next, the test which measures the electromagnetic wave absorption characteristic with respect to the electromagnetic wave (frequency: 5.8 GHz) of the sheet | seat main body 30 obtained as mentioned above was done. As shown in FIG. 7, the test is performed by absorbing characteristics [unit: dB] when the incident angle θ with respect to the sheet body 30 is 0.0 ° ≦ θ ≦ 47.5 °, and 47.5 ° < Absorption characteristics when θ ≦ 50.0 ° were measured. The results are as shown in Table 1 below.

FIG. 1 is a perspective view showing an overall configuration of a radio wave absorption sheet according to Embodiment 1 of the present invention. FIG. 2 is a partial cross-sectional view showing an enlarged main part of the radio wave absorbing sheet. FIG. 3 is a perspective view showing a state in the middle of installing the radio wave absorbing sheet on the support column. FIG. 4 is a side view showing a state in which the radio wave absorbing sheet is installed on the support column. FIG. 5 is a view corresponding to FIG. 1 and showing the overall configuration of the radio wave absorption sheet according to Embodiment 2 of the present invention. FIG. 6 is a cross-sectional view schematically showing an installation state of the radio wave absorbing sheet. FIG. 7 is a cross-sectional view schematically showing a test procedure performed for examining the radio wave reflection characteristics of the radio wave absorption sheet according to the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Radio wave absorption sheet 20 Holding body 30 Sheet | seat main body 31 Radio wave absorption layer 32 Radio wave reflection layer 50 Blind rivet (fastening tool)
60 Prop (long structure)

Claims (7)

A radio wave absorbing sheet installed to cover the long structure around the long structure,
A sheet body that is flexible and absorbs radio waves of a predetermined frequency;
An electromagnetic wave absorbing sheet comprising: a holding body that holds the sheet main body in a curved cross section. The radio wave absorbing sheet according to claim 1,
The holding body is formed by dividing a tubular material that can surround at least a part of the lengthwise structure in the longitudinal direction into a plurality of parts in the circumferential direction,
The electromagnetic wave absorbing sheet, wherein the sheet main body is held in a laminated state on the holding body. The radio wave absorbing sheet according to claim 2,
The electromagnetic wave absorbing sheet, wherein the holding body is formed by dividing the pipe material into two substantially equal parts in the circumferential direction. The radio wave absorbing sheet according to claim 1,
The radio wave absorbing sheet, wherein the sheet main body is adhered to a holding body with an adhesive. The radio wave absorbing sheet according to claim 1,
An electromagnetic wave absorbing sheet, wherein the sheet main body is fixed to a holding body by a fixing tool. The radio wave absorbing sheet according to claim 1,
The sheet main body is laminated on the radio wave absorption layer so as to be positioned on the long structure side of the radio wave absorption layer, and a radio wave absorption layer that attenuates while transmitting a part of the radio waves incident on the sheet main body, A radio wave absorption sheet comprising: a radio wave reflection layer that reflects the part of the radio waves transmitted through the radio wave absorption layer. An installation method of a radio wave absorption sheet, wherein the radio wave absorption sheet according to claim 1 is installed around a long structure so as to cover the long structure,
A plurality of the radio wave absorption sheets are arranged with respect to the long structure so that the sheet main body of the plurality of radio wave absorption sheets surrounds at least a part of the length structure in the length direction over the entire circumference. And
Thereafter, the plurality of radio wave absorption sheets are bundled to install the plurality of radio wave absorption sheets.

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