JPH04337700A - Radio wave absorber - Google Patents

Abstract

PURPOSE:To provide a radio wave absorber in which a radio wave transparent part is not generated on a wall surface in a radio wave darkroom, etc. CONSTITUTION:In a radio wave absorber of this invention, a radio wave transparent vessel 20 is disposed on an entire surface of any of a wall surface 24, a ceiling surface 22 and a floor 23 in a radio wave darkroom, and the vessel 20 is filled with dielectric loss particles 25, 26 having films made to carbon black and/or graphite and binder on surface of prefoamed beads.

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 used for the walls of a radio anechoic chamber.

0002

2. Description of the Related Art A radio wave absorber includes, for example, a plurality of quadrangular pyramid-shaped radio wave absorbers 2 on the surface of a base 1, as shown in FIG.
It has been established. This radio wave absorber is used by adhering the back surface 3 of the base 1 to the wall, ceiling, floor, etc. of a radio anechoic chamber via an adhesive or the like.

Conventionally, such radio wave absorbers include, for example,
As described in JP-A-2-174198, pre-expanded polystyrene beads, pre-expanded polyethylene beads, etc. are placed inside a hollow outer shell made of radio-transparent paper or thermoplastic synthetic resin material. It is constructed by filling the surface of pre-foamed beads (primary foam beads) with dielectric loss particles having a coating formed of carbon black and/or graphite and a binder. For example, as shown in FIG. 6, the radio wave absorber 10 has a radio-transparent outer shell 11 provided with a radio-transparent partition plate 12 similar to the outer shell 11, and has dielectric loss particles 13, 14. It consists of filling. The dielectric loss particles 13 and the dielectric loss particles 14 have different dielectric constants.

However, when a plurality of these radio wave absorbers 10 are arranged on the wall surface of the radio anechoic chamber, the outer shell 11
Since the radio wave absorbers 10 are transparent in terms of radio waves, the adjacent portions of the radio wave absorbers 10 become transparent in terms of radio waves, as shown in FIG. 5, and there is a problem in that radio wave absorption is not performed in these adjacent portions.

[0005]

[Problems to be Solved by the Invention] The present invention has been made to solve these problems, and an object of the present invention is to provide a radio wave absorber that does not have radio wave transparent parts. shall be.

[0006]

[Means for Solving the Problems] The radio wave absorber of the present invention is
A radio-transparent container is placed over the entire surface of at least one of the walls, ceiling, and floor of the anechoic chamber, and carbon black is placed on the surface of the pre-foam beads in the container. and/or filled with dielectric loss particles having a coating formed of graphite and a binder.

As described above, in the present invention, a radio wave transparent container is arranged over the entire surface of at least one of the surfaces, and the dielectric loss particles are filled in this container to serve as a radio wave absorber. At least no radio-transparent portions occur on either surface. Therefore, according to the present invention, the radio wave absorption performance can be improved compared to conventional radio wave absorbers in which the adjacent portions of the radio wave absorbers are transparent in terms of radio waves.

The structure of the present invention will be explained in detail below with reference to the drawings. In the present invention, a container 20 as shown in FIG. 1 is disposed over the entire surface of at least one of the walls, ceiling, and floor of the anechoic chamber, that is, on one or more of these surfaces. do. The inside of this container 20 may be partitioned with a partition plate 21 as necessary. The material of the partition plate 21 is the same as that of the container 20.

FIG. 2 shows how the container 20 is placed on the wall of the anechoic chamber. In FIG. 2, the container 20 is arranged on a wall surface 24 between a ceiling surface 22 and a floor surface 23 over the entire surface of the wall surface 24. In FIG. Inside the container 20, there are dielectric loss particles 25,
26 is filled. The dielectric loss particles 25 and the dielectric loss particles 26 have different dielectric constants. Note that when the container 20 is filled with a single dielectric loss particle, the partition plate 21 is not necessary.

As shown in FIGS. 3 and 4, in the container 20, at least one of the portions in contact with the ceiling surface 22, wall surface 24, and floor surface 23 may be omitted and replaced with these surfaces. Further, the surface 27 of the container 20 is flat (as shown in FIG. 2).
It may be flat), or it may consist of a plurality of conical, triangular pyramidal, quadrangular pyramidal, wedge-shaped, etc. protrusions. ■
Dielectric loss particles 25, 26.

[0011] A coating consisting of carbon black and/or graphite and a binder is formed on the surface of the pre-foamed beads. As pre-foam beads,
As in conventional radio wave absorbers, pre-foamed polystyrene beads, pre-foamed polyethylene beads, and styrenic copolymers such as styrene-acrylonitrile copolymers in which part of the styrene is replaced with other monomers such as acronitrile are used. Just use it. In particular, bulk specific gravity 0.010~0
．． It is preferable to use pre-expanded polystyrene beads having a particle size of 0.030 and an average particle diameter of 2.0 to 20 mm.

[0012] Carbon black and graphite may also be the same as those used in conventional radio wave absorbers. In particular, dibutyl phthalate oil absorption 100-40
Preferably, a high structure carbon black of 0 cc/100 g is used. Further, graphite preferably has an average particle size of 0.5 to 30 microns. The binder may be a rubber-based or resin-based binder as in conventional radio wave absorbers. The rubber binder is, for example, a dispersion of rubber such as SBR, CR, NBR, etc. and water. Examples of the resin binder include epoxy resin,
It is a dispersion consisting of water and synthetic resins such as urethane resin, vinylidene chloride resin, and acrylic resin.

[0013] The blending ratios of these pre-foamed beads, carbon black and/or graphite, and binder may be the same as in conventional radio wave absorbers. The dielectric loss particles 25 and 26 are pre-foamed beads that are independent from each other without being fixed to each other via a binder. This includes, for example, prefoam beads, carbon black and/or graphite,
It can be obtained by drying the binder formulation with hot air while stirring.

■ Container 20. Made of radio-transparent material. As this material, radio-transparent paper or thermoplastic synthetic resin material may be used as in the conventional case. ■
The filling of the dielectric loss particles 25 and 26 into the container 20 may be performed continuously. In this case, filling can be carried out continuously by direct air blowing or gravity dropping. Therefore, it becomes possible to fill the radio wave absorber at the work site, making it easier to install the radio wave absorber than in the past.

[0015]

[Effects of the Invention] As explained above, according to the present invention, a radio-transparent container is disposed over the entire surface of at least one of the walls, ceiling, and floor of the anechoic chamber. However, since the electromagnetic wave absorber is constructed by filling the container with dielectric loss particles, no transparent portion is formed on at least one of the surfaces. Therefore, according to the present invention, the radio wave absorption performance can be improved compared to conventional radio wave absorbers in which the adjacent portions of the radio wave absorbers are transparent in terms of radio waves.

Furthermore, according to the present invention, the radio wave absorber can be made into a radio wave absorber by continuously filling the container with dielectric loss particles at a work site, etc. Construction becomes easier.

[0017]

[Brief explanation of drawings]

FIG. 1 is a perspective view of an example of a radio-transparent container used in the present invention.

FIG. 2 is an explanatory diagram showing a state in which the container of FIG. 1 is placed over the entire wall surface of an anechoic chamber and the container is filled with dielectric loss particles.

FIG. 3 is an explanatory diagram showing another example of FIG. 2;

FIG. 4 is an explanatory cross-sectional view taken along line BB in FIG. 3;

FIG. 5 is an explanatory plan view showing how the radio wave absorber is arranged on the wall surface of the radio anechoic chamber.

FIG. 6 is an explanatory cross-sectional view of an example of a conventional radio wave absorber.

FIG. 7 is a perspective explanatory view of an example of a radio wave absorber.

[Explanation of symbols]

Claims (1)

[Claims] Claim 1: A radio-transparent container is placed over at least one of the walls, ceiling, and floor of the anechoic chamber, and pre-foam beads are placed in the container. A radio wave absorber filled with dielectric loss particles having a film formed of carbon black and/or graphite and a binder on the surface thereof.