JP2002180568A - Electromagnetic wave absorptive object and its execution method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic wave absorptive object and its execution method ensuring the thickness of a uniform absorption layer and, which is at the same time, excellent in workability. SOLUTION: The electromagnetic wave absorptive object 1 is so constituted that an electromagnetic wave absorbing material W compounding an electrically conductive oxidizing titanium with a basic material in a space 3a is applied to a net body 3 forming a net-like body put on the surface of an electromagnetic wave passive reflector 2 with the thickness (d) of a net body 3 as a standard. As the net body 3, it is formed of a clear resin material as the electromagnetic wave. The net body 3 constituting the net-like body manufactures a clear net as the electromagnetic wave such as a nylon tulle or the like in a millimeter wave zone with a prescribed diameter of a strand. A cross sectional form of the surface at right angles to the longitudinal direction of the strand constituting the net body 2 is not specially limited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio wave absorber widely used for ships, aircrafts, and the like, and a method of constructing the same. It concerns the construction method.

[0002]

2. Description of the Related Art In recent years, research on the use of radio waves in the microwave band and the millimeter wave band has been actively conducted in various fields, and accordingly, radio wave absorbers for preventing electromagnetic interference have attracted attention.

[0003] As a construction method of the radio wave absorber, for example,
A method of applying a radio wave absorbing material based on an uncured resin composition to the surface of a reflecting plate and curing the material (hereinafter referred to as a coating type)
And a method of adhering a sheet-like absorbing layer to the surface of a reflector via an adhesive (hereinafter referred to as an adhesive type).

In the so-called "matching type absorption" in which radio waves are absorbed by an absorption layer provided on the surface of a reflection plate, the thickness of the radio wave absorption layer that can match radio waves in the millimeter wave band is 1 mm or less. In this case, it is very difficult to bond the absorption layer formed into a thin film to the surface of the reflection plate, and the application was mainly performed by a coating type.

[0005] In a coating type application method, a radio wave absorbing material based on an uncured resin composition is applied to the surface of a reflector by spraying to form an absorbing layer having a uniform thickness. In order to obtain the desired thickness, it is necessary to repeat the coating with a small thickness many times while checking the thickness, and there is a problem that workability is extremely poor.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a radio wave absorber excellent in workability while ensuring a uniform thickness of an absorbing layer, and a method of installing the same.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a first radio wave absorber in which a radio wave absorbing material is applied to a net attached to the surface of a reflector. It is assumed that.

The reticulated body is a reticulated body made of a radio wave transparent resin material or a honeycomb structure made of a radio wave transparent material.

The radio wave absorbing material is a radio wave absorber composition obtained by mixing 5 to 50 parts by weight of a conductive titanium oxide with respect to 100 parts by weight of a base material. The gist of the present invention is that the composition is a radio wave absorber composition containing 10 parts by weight or less of a carbon black based on 100 parts by weight of a base material.

[0010] Further, in the method of constructing a radio wave absorber according to the present invention, a net is mounted on a surface of a reflector in advance, and a radio wave absorbing material in which conductive titanium oxide is mixed with a base material is applied on the surface. It is intended to be dried and cured.

Further, in another method of installing a radio wave absorber according to the present invention, a honeycomb structure is mounted on a surface of a reflector in advance, and conductive titanium oxide is mixed with a base material on cells and surfaces of the honeycomb structure. The gist of the invention is to dry and harden after applying the radio wave absorbing material.

Another method of applying the radio wave absorber is to form a sheet-shaped radio wave absorption layer containing a net made of a radio wave transparent material in advance, and to form the radio wave absorption layer on a reflector. The gist is to adhere to the surface of the substrate.

With the above configuration, the radio wave absorbing material can be applied while using the surface position of the mesh attached to the surface of the reflector as a guide, so that a radio wave absorbing layer having a uniform thickness can be easily formed and the radio wave absorbing material can be easily formed. This makes it possible to apply the absorbing material efficiently.

In addition, the radio wave absorbing layer having a uniform thickness can be formed, and the formed thin sheet-shaped radio wave absorbing layer has a built-in reticulate body to impart rigidity to the absorbing layer and adhere. Work can be facilitated.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

In each of the drawings, the same components are denoted by the same reference numerals, and redundant description will be omitted.

FIG. 1A is a plan view of a radio wave absorber constituted by a net (net) according to the first embodiment of the present invention, and FIG. 1B is a sectional view taken on line AA of FIG. 1A. 2A is a plan view of a radio wave absorber constituted by a net-like body (honeycomb structure) according to a second embodiment of the present invention, and FIG. 2B is a plan view of FIG. (A) is a cross-sectional view taken along the line BB.

The radio wave absorber 1 according to the first embodiment shown in FIGS. 1A and 1B has a thickness of the net 3 on a net 3 constituting a net attached to the surface of a radio wave reflector 2. On the basis of d, the gap 3a is coated with a radio wave absorbing material W. The net 3 is a net made of a resin material that is transparent in radio waves.

In the millimeter wave band, the net 3 constituting the net is made of a radio-transparent net such as nylon tulle with a specified wire diameter, and is made of a thermoplastic resin such as, for example, a thermoplastic resin. Polyolefin resins such as polyethylene and polypropylene, polyamide resins such as nylon 6 and nylon 66, polyethylene terephthalate, polybutylene terephthalate and the like, polyester resins and the like, or a mixture thereof are used.

The cross-sectional shape of a plane perpendicular to the longitudinal direction of the wires constituting the net 2 is not particularly limited.

The radio wave absorber 1 according to the second embodiment shown in FIGS. 2A and 2B includes a honeycomb structure 4 which forms a mesh attached to the surface of a radio wave reflection plate 2, and a thickness of a cell 5. Based on the height h, a radio wave absorbing material W is applied to the gap 5 a of the cell 5.

In the microwave body, the applied thickness of the radio wave absorbing material W is as thick as 2 to 4 mm. Therefore, the above-described honeycomb structure 4 is used instead of the mesh 3 made of nylon tulle or the like. As a material of the honeycomb core, a radio wave transparent material such as a paper core, a nomex core, and a glass core is preferable.

As the radio wave absorbing material W used in the first and second embodiments, a radio wave absorber composition in which a conductive titanium oxide and a conductive carbon black are blended in a base material is used. As the base material, a material selected from a thermoplastic resin, a thermosetting resin, various rubbers, an elastomer and the like is used.

Examples of the thermoplastic resin include polyolefin resins such as polyethylene and polypropylene; polyamide resins such as nylon 6 and nylon 66; polyethylene terephthalate and polybutylene terephthalate; polyester resins; and mixtures thereof.

The thermosetting resin is appropriately selected from, for example, epoxy resins, polyurethane resins, polyester resins, phenol resins and the like. The type and amount of the curing agent are not particularly limited, since a commonly used curing agent is used.

The composition of the radio wave absorbing material W is determined in consideration of the type of the base material, the type of the conductive titanium oxide and the type of the conductive carbon black to be added thereto, and the variable factors of the complex relative permittivity of the material depending on the compounding amount. The amount of conductive titanium oxide is 5 to 50 parts by weight, preferably 10 to 100 parts by weight of the base material.
Preferably, the amount of the conductive carbon black is 10 parts by weight or less based on 100 parts by weight of the base material.

The conductive titanium oxide is effective in broadening the absorption performance, but if the compounding amount is less than 5 parts by weight with respect to 100 parts by weight of the base material, the complex relative permittivity of the material becomes real part and imaginary part. Both parts become too low to match radio waves, and if it exceeds 50 parts by weight, on the contrary, both the real and imaginary parts of the complex relative permittivity become too high to match radio waves.

In addition, conductive carbon black is used to increase the imaginary part of the complex relative permittivity so that the thickness of the radio wave absorption layer can be reduced without affecting the radio wave absorption performance. It is preferable to mix them, but if the compounding amount exceeds 10 parts by weight with respect to 100 parts by weight of the base material, the viscosity of the material increases and the workability deteriorates.

The radio wave reflecting plate 2 includes a resin molded body obtained by impregnating a carbon fiber, a metal fiber, a wire net or the like with a thermosetting resin or a thermoplastic resin, a metal plate, a resin plate containing metal powder, It is composed of a material selected from a metal sprayed resin plate or the like.

Next, a method of installing the radio wave absorber will be described.

First, a first invention relating to a coating type application method is to mount a mesh (net 3 or honeycomb structure 4) on the surface of a radio wave reflector 2 in advance, and to form a conductive titanium oxide on the surface thereof. After applying the radio wave absorbing material W mixed with the material, it is dried and cured.

When the radio wave absorbing layer is formed on the radio wave reflecting surface, a net (net 3 or honeycomb structure 4) having a thickness d substantially equal to the thickness of the radio wave absorbing layer to be applied in advance is applied to the radio wave absorbing layer. It is mounted on the surface of the reflector 2. In this case, it is preferable that the net is adhered to the surface of the reflector from the viewpoint of stability of the absorbing layer after construction.

Thereafter, a radio wave absorbing material W is applied to a portion of the radio wave reflecting surface that is not covered by the net, that is, an exposed surface portion of the reflector, using the position of the surface of the net as a guide. This makes it possible to apply the radio wave absorbing layer to a uniform thickness, and in the past, it was necessary to apply the radio wave absorbing layer several times with a small thickness to obtain a uniform thickness. A desired thickness can be obtained by coating.

Another construction method of the radio wave absorber according to the second invention relating to the adhesion type construction is a sheet in which a mesh (net 3 or honeycomb structure 4) made of a radio wave transparent material is built in advance. A radio wave absorbing layer is formed in a shape, and the radio wave absorbing layer is bonded to the surface of the reflector.

In this case, it is only necessary that the net is partially or entirely buried in the radio wave absorption layer, so that the thickness d of the net need not be equal to the thickness of the radio wave absorption layer.

Thus, the radio wave absorbing layer is ensured to have a uniform thickness by factory production, and the radio wave absorbing layer is provided with rigidity so that the net-like body is built in the sheet-shaped radio wave absorbing layer. Facilitates adhesion to surfaces.

FIGS. 3 to 6 show the results of examples in which the radio wave absorption performance (dB) of the installed radio wave absorber was measured by the reflected power method. [Example] [Example 1] Netting member 2 made of nylon resin having a thickness of 0.4 mm
Is adhered on an aluminum plate, and the conductive titanium oxide 32
The net 2 was sprayed with a radio wave absorbing material comprising an epoxy resin containing 1 part by weight of conductive carbon black and 1 part by weight of a conductive carbon black to obtain a radio wave absorbing layer having a thickness of 0.392 mm.

FIG. 3 shows the result of measuring the absorption performance of the obtained radio wave absorber. [Example 2] Nylon resin net 2 having a thickness of 0.2 mm
Are laminated on an aluminum plate and sprayed so that the net 2 is impregnated with a radio wave absorbing material made of an epoxy resin containing 32 parts by weight of conductive titanium oxide and 1 part by weight of conductive carbon black. To obtain a radio wave absorbing layer having a thickness of 0.573 mm.

FIG. 4 shows the results of measuring the absorption performance of the obtained radio wave absorber. Example 3 An epoxy resin containing 32 parts by weight of conductive titanium oxide and 3 parts by weight of conductive carbon black was prepared by bonding a mesh body 2 made of polyethylene resin having a thickness of 0.65 mm to an aluminum plate. Was applied with a spray so as to impregnate the net 2 to obtain a radio wave absorbing layer having a thickness of 0.76 mm.

FIG. 5 shows the results of measuring the absorption performance of the obtained radio wave absorber. [Example 4] Core thickness: 3.63 mm,: 3.75 mm,:
Three types of honeycomb structures of 3.63 mm (paper honeycomb: manufactured by Showa Aircraft Industry Co., Ltd.) were respectively bonded on an aluminum plate, and 32 parts by weight of conductive titanium oxide and 1 part by weight of conductive carbon black. (In the case of,), a radio wave absorbing material made of an epoxy resin containing (in the case of) conductive titanium oxide 32 parts by weight and conductive carbon black (in the case of) is applied by spraying, and the thickness of the absorber : 3.
A radio wave absorption layer of 71 mm,: 3.85 mm,: 3.75 mm was obtained.

FIG. 6 shows the result of measuring the absorption performance of the obtained radio wave absorber, and it was found that the radio wave absorption performance was obtained over a wide frequency range as a whole.

In each of the above embodiments, the spray is used as a method of applying the radio wave absorbing material. However, the present invention is not limited to this embodiment, and the application may be performed using a spatula or a brush. It is.

[0043]

The present invention is constructed as described above, and has the following excellent effects. (a) In the case of the coating type construction, by applying the radio wave absorbing material with the surface position of the net having a thickness approximately equivalent to the thickness of the radio wave absorbing layer as a guide, the uniformity of the radio wave absorbing layer The thickness can be ensured, and construction with excellent workability can be performed. (b) In the case of the adhesive type construction, a uniform thickness of the radio wave absorption layer produced by the factory can be ensured, and the radio wave absorption layer has a built-in mesh made of a radio wave transparent material. Rigidity is imparted to the radio wave absorption layer, and the effect is excellent in workability in bonding.

[Brief description of the drawings]

FIG. 1A is a plan view of a radio wave absorber constituted by a net (net) according to a first embodiment of the present invention;
(B) is a sectional view taken along the line AA of (a).

FIG. 2A is a plan view of a radio wave absorber constituted by a mesh body (honeycomb structure) according to a second embodiment of the present invention, and FIG. 2B is a cross-sectional view taken along line BB of FIG. FIG.

FIG. 3 is an explanatory graph showing measurement results of the radio wave absorption performance of the radio wave absorber constructed according to the first embodiment of the present invention.

FIG. 4 is a graph explanatory view showing the measurement results of the radio wave absorption performance of another radio wave absorber constructed according to the second embodiment of the present invention.

FIG. 5 is an explanatory graph showing the measurement results of the radio wave absorption performance of another radio wave absorber constructed according to the third embodiment of the present invention.

FIG. 6 is an explanatory graph showing measurement results of the radio wave absorption performance of another radio wave absorber constructed according to the fourth embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 radio wave absorber 2 radio wave reflector 3 net 3 a void 4 honeycomb structure 5 cell 5 a void W radio wave absorbing material d net thickness h cell thickness

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 9/00 H01F 1/00 CF term (Reference) 2E001 DH01 GA06 GA32 GA87 HA11 HB04 HC07 HD11 JA29 JB01 JB07 JD02 JD08 LA04 4F100 AA21C AA37C AB10 AK01B AK46 AK53 AT00A BA03 BA07 DC01B DC11B EC182 EH462 EH61 EJ082 EJ82 EJ862 GB31 JD08A JD08C JG01C JL01 JN01B 5E040 CA13 5E321 BB24 BB23BB24BB23BB

Claims (9)

[Claims] 1. A reticulated body mounted on the surface of a radio wave reflecting plate,
A radio wave absorber made by applying a radio wave absorbing material. 2. The radio wave absorber according to claim 1, wherein the net is a net made of a radio wave transparent resin material. 3. The radio wave absorber according to claim 1, wherein the mesh is a honeycomb structure made of a radio wave transparent material. 4. The radio wave absorber according to claim 1, wherein said radio wave absorbing material is a material in which conductive titanium oxide is blended in a base material. 5. The radio wave absorber composition according to claim 1, wherein said radio wave absorbing material comprises 5 to 50 parts by weight of conductive titanium oxide in 100 parts by weight of said base material.
Or the radio wave absorber according to 4. 6. The radio wave absorber composition according to claim 1, wherein said radio wave absorbing material comprises 10 parts by weight or less of conductive carbon black based on 100 parts by weight of a base material.
Or the radio wave absorber according to 5. 7. A method for constructing a radio wave absorber in which a net-like body is previously mounted on the surface of a radio wave reflection plate, a radio wave absorption material containing a conductive titanium oxide as a base material is applied on the surface, and then dried and hardened. 8. A radio wave which is preliminarily mounted on a surface of a radio wave reflecting plate, and a cell and a surface of the honeycomb structure are coated with a radio wave absorbing material containing conductive titanium oxide as a base material, and then dried and cured. Construction method of absorber. 9. A sheet-like radio wave absorbing layer incorporating a net made of a radio wave transparent material is formed in advance, and the radio wave absorbing layer is bonded to the surface of the reflector. Method.