JPH10196005A - Radio wave absorber panel and radio wave absorption wall - Google Patents

Abstract

(57) [Problem] To provide good workability, reduce cost, reduce weight, exhibit excellent radio wave absorption characteristics that can cope with not only VHF band but also UHF band TV radio wave, and generate TV ghost. To prevent SOLUTION: A ferrite board 2 formed into a strip shape by a compound in which ferrite grains and a binder are mixed.
A plurality of sheets 2 are fixed to a metal plate 26 so as to be arranged at equal intervals in the width direction with a gap 24 therebetween to form a radio wave absorber panel 20. The gap may be an air gap or may be filled with a non-magnetic material. The total gap size is 3 of the total panel width.
30%, and the thickness of the ferrite board is 20 to 50 mm. Exterior decorative material is provided on the front side of the radio wave absorber panel, lightweight concrete is cast on the metal plate side on the back side, and the whole is integrated into a plate shape, and the gap is formed in the direction of the electric field when viewed from the direction of arrival of TV radio waves. A radio wave absorption wall is formed in an array.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a radio wave absorber panel in which a plurality of strip-shaped ferrite boards are arranged at regular intervals in a width direction with a gap therebetween and fixed to a metal reflector. It is related to radio wave absorption walls.
This radio wave absorbing wall is used for an outer wall material of a high-rise building or the like as a measure for preventing a television ghost (double image or triple image).

[0002]

2. Description of the Related Art The reflection of television waves causes ghosts on television screens. In particular, when the reflection area is large, as in a high-rise building, the influence is remarkable, and so-called electromagnetic interference (reception interference) becomes a problem. Therefore, in a high-rise building, various outer wall materials having a radio wave absorbing function are used in order to prevent the reflection of TV radio waves on the wall surface.

A typical example of the outer wall material is a radio wave absorbing precast concrete curtain wall.
This is a PC (precast concrete) panel in which reinforcing steel is placed inside and a lightweight concrete is poured into a plate shape, and a large number of ferrite tiles (a tile formed by forming ferrite into a plate shape and hardening: Is, for example, 1
(00 mm square, 10 to 13 mm thick) are attached side by side, and the top is covered with an exterior decorative material such as stone or tile.

[0004] In addition, a structure has been developed in which a ferrite mortar layer in which ferrite particles are mixed with cement is formed on the entire surface of one side of a PC panel, and the ferrite mortar layer is used as a base for an exterior decorative material.

[0005]

Generally, ferrite tiles have a problem that a radio wave absorption band is narrow. Moreover, this type of ferrite tile has a VHF of 90 to 220 MHz.
It is used for the countermeasure against the television ghost in the band, and has not been used as the countermeasure for the television ghost in the UHF band of 400 to 800 MHz.
However, in recent years, the construction of high-rise buildings has been increasing in local cities where television waves in the UHF band are used, and countermeasures are being sought.

Further, ferrite tiles require precise dimensional processing after sintering, and thus have poor workability and high manufacturing cost. This is because ferrite tiles are sintered products, so it is difficult to achieve the specified dimensional accuracy by simply sintering, but when arranging many ferrite tiles, the radio wave absorption performance changes depending on the thickness and arrangement of the ferrite tiles. Therefore, it is necessary to finish by post-processing so as to obtain a predetermined dimensional accuracy. The use of ferrite tiles also has the disadvantage of increasing weight. Furthermore, the work of arranging and fixing a large number of such ferrite tiles with high accuracy is extremely poor in workability.

[0007] On the other hand, a construction using only a single layer of ferrite mortar in which ferrite grains are mixed with cement has good workability, but has low magnetic properties as compared with the ferrite tiles described above, and it is difficult to exhibit radio wave absorption performance over a wide band. is there.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a television ghost prevention which has good workability, can be reduced in cost, can be reduced in weight, and has excellent radio wave absorption characteristics capable of coping with not only VHF band but also UHF band television wave. An object of the present invention is to provide a radio wave absorber panel and a radio wave absorbing wall for countermeasures.

[0009]

According to the present invention, a plurality of ferrite boards formed in a strip shape by a compound in which ferrite grains and a binder are mixed are arranged at equal intervals in the width direction with a gap therebetween. It is a radio wave absorber panel fixed to a metal reflector. Here, the binder refers to a material that bonds ferrite grains to each other and performs a function of stably maintaining a shape. The above-mentioned gap refers to a gap in a magnetic sense, and may be an air gap (air gap). However, a construction in which concrete or synthetic resin (for example, foaming resin) is filled has better workability. The total gap size is about 3 to 30% of the panel width,
The thickness of the ferrite board is about 20 to 50 mm.

The present invention is also directed to a television, in which an exterior decorative material is provided on the front side of such a radio wave absorber panel, lightweight concrete is cast on the metal reflector on the back side, and the whole is integrated into a plate shape. This is a radio wave absorbing wall in which the gaps are arranged in the direction of the electric field when viewed from the arrival direction of the radio wave.

As shown in FIG. 6, a ferrite board 10 formed by mixing ferrite grains and a binder is disposed with a gap in the direction of an electric field component, and is fixed to a metal plate 12 to form a panel. It is possible to control the absorber material constants (complex magnetic permeability μ, complex dielectric constant ε). They are mainly the filling ratio of the ferrite grains in the ferrite board and the ratio of the total of the gap dimensions to the entire width of the panel (that is, when the gap width is g and the ferrite board width is a, g × 100 (%) / (a + g). 6), the thickness t of the ferrite board, and the structure of the panel (FIG. 6).
(A) or a gap filling structure in which the gap is filled with the non-magnetic filler 14 as shown in FIG. 6B). With this configuration, broadband characteristics can be obtained without changing the panel thickness, as compared with the radio wave absorption characteristics when no gap is provided.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A ferrite board is an elongated plate-like body formed by mixing ferrite grains and a binder into a strip shape as described above. The material of the ferrite is, for example, M
A material conventionally used for a radio wave absorber, such as a g-Zn system, a Mn-Zn system, or a Ni-Zn system, may be used, or a powder or a mixture of these materials may be used. The particle size varies depending on the binder used, the mixing ratio, and the like, but is selected, for example, from the range of about 0.1 to 5 mm. When the binder is used for an outer wall or the like, an inorganic binder such as cement, which has already been used, is preferable. However, an organic binder such as a synthetic resin or a synthetic rubber may be used depending on the application and use conditions. The mixing ratio between the ferrite grains and the binder varies depending on the particle size of the ferrite grains, the binder, and the like. However, when cement is used, the ferrite grains are 7 to 9 parts by weight per 1 part by weight of the binder. When the mixing ratio of ferrite grains is small (6 parts by weight), the absorption characteristics are deteriorated as shown in FIG. 7, and when it is too large (exceeding 9 parts by weight), cement cannot be molded. However, when an organic binder (for example, epoxy resin) is used, the ratio of ferrite grains is further increased (for example, 1%).
About 5 parts by weight). The metal reflector may be a simple flat plate, a mesh, a perforated plate, a stitched reinforcing bar,
A honeycomb structure or the like may be used.

In the case of an air gap structure as shown in FIG. 6A, as a measure against TV ghost in the VHF band (90 to 220 MHz), the total gap size is set to 3 to 7 of the entire panel width.
%. As shown in FIG. 8, the band is too narrow at 2%, and the band is widened at 8%, but the absorption characteristics deteriorate. UHF band (400 ~
(800 MHz) As a countermeasure against TV ghost, it is preferable that the total gap size is about 15 to 25% of the entire panel width. This is because, as shown in FIG. 9, the absorption characteristics deteriorate at 10% or 30%. In these structures, the thickness of the ferrite board is preferably about 20 to 40 mm. As shown in FIG. 10, the band becomes too narrow at 15 mm, and the band widens at 45 mm, but the absorption characteristics are deteriorated.

In the case of a gap filling structure as shown in FIG. 6B, it is preferable that the total gap size is about 3 to 30% of the entire panel width. This is because, as shown in FIG. 11, the absorption characteristics deteriorate at 2% or 35%. The thickness of the ferrite board is preferably about 20 to 50 mm.
As shown in FIG. 12, at 15 mm, the absorption characteristics are poor,
This is because the band becomes too narrow with mm.

[0015]

FIG. 1 is a perspective view showing one embodiment of a radio wave absorber panel according to the present invention. This radio wave absorber panel 20
Is a method in which a plurality of ferrite boards 22 each formed into a strip shape by using a compound in which ferrite grains and cement are mixed using cement as a binder are arranged such that a plurality of ferrite boards 22 are arranged at equal intervals in the width direction with a gap 24 therebetween. The structure is fixed to Ferrite grains having a particle size of 0.1 to 5 mm mixed at a ratio of 3 parts by weight of Mg-Zn based ferrite to 7 parts by weight of Mn-Zn based ferrite, and a ratio of 8 parts by weight of ferrite to 1 part by weight of cement A ferrite board 22 in the form of a strip was formed using the compound mixed in the above. The dimensions of the ferrite board 22 are 4 m × 0.
It is 95 m and 3.5 cm thick. This ferrite board 2
3 were arranged side by side with a gap 24 of 5 cm, and the overall panel size was 4 × 3 m in length and width. The gaps 24 are arranged in the direction of the electric field when viewed from the arrival direction of the television wave. As a result, a radio wave absorber for TV ghost countermeasures showing excellent radio wave absorption performance with a reflection loss of 20 dB or more in the VHF band was obtained.

In such a structure, the ferrite board 22 and the metal plate 26 may be fixed by a fitting (not shown) or the like, but may be bonded in some cases. The mounting bracket may be configured so that a part thereof is embedded and fixed in the ferrite board in advance, or may be configured to be hooked on an edge of the formed ferrite board. Instead of the metal plate, a mesh, a perforated plate, a reinforcing bar assembled in a stitch shape or a lattice shape, or a honeycomb structure may be used.

In the above embodiment, a radio wave absorber having a similar structure was obtained by using a synthetic resin (epoxy resin) instead of cement as a binder. The size and gap size of the ferrite board are the same. However, a compound obtained by mixing 15 parts by weight of ferrite with respect to 1 part by weight of the synthetic resin was used. In this way, a radio wave absorber for TV ghost countermeasures showing excellent radio wave absorption performance in the VHF band was obtained.

Ferrite grains having a particle size of 0.1 to 5 mm mixed at a ratio of 3 parts by weight of Mg-Zn based ferrite to 7 parts by weight of Mn-Zn based ferrite, and 8 parts by weight of ferrite per 1 part by weight of cement The compound mixed in the ratio of parts was used to form a ferrite board having a length of 4 m x 0.80 m and a thickness of 2.5 cm. Three ferrite boards were arranged with a gap of 20 cm, and the overall panel size was 4 × 3 m. By using this, a radio wave absorber for TV ghost countermeasures showing excellent radio wave absorption performance with a reflection loss of 20 dB or more in the UHF band was obtained. FIG. 13 shows the radio wave absorption characteristics.

In the above embodiment, a radio wave absorber having a similar structure was obtained by using a synthetic resin (epoxy resin) instead of cement as the binder. The size and gap size of the ferrite board are the same. However, a compound obtained by mixing 15 parts by weight of ferrite with respect to 1 part by weight of the synthetic resin was used. In this way, a radio wave absorber for TV ghost countermeasures showing excellent radio wave absorption performance in the UHF band was obtained.

FIG. 2 is a perspective view showing another embodiment of the radio wave absorber panel according to the present invention. The radio wave absorber panel 30 uses cement as a binder, and a plurality of strip-shaped ferrite boards 32 formed of a compound of ferrite grains and cement are arranged at regular intervals with a gap therebetween in the width direction. Is fixed to the metal plate 36 as described above. Here, the gap is not an air gap (air gap), but has a structure filled with a non-magnetic filler 38 (an inorganic substance such as concrete, or an organic substance such as styrene foam or urethane resin). Ferrite grains having a particle size of 0.1 to 5 mm mixed at a ratio of 3 parts by weight of Mg-Zn based ferrite to 7 parts by weight of Mn-Zn based ferrite, and a ratio of 8 parts by weight of ferrite to 1 part by weight of cement A ferrite board 32 in the form of a strip was formed using the compound mixed in the above. The dimensions of the ferrite board 32 are 4 m × 0.80 m in length and width and 3.0 cm in thickness. Three ferrite boards 32 were arranged with a gap of 20 cm, and the overall panel size was 4 × 3 m. The gap is filled with concrete as the filler 38, and the gap is arranged in the direction of the electric field when viewed from the direction of arrival of the television wave. Thereby, the reflection loss is 20 dB in the VHF band.
A radio wave absorber for TV ghost countermeasures showing the above excellent radio wave absorption performance was obtained. FIG. 14 shows the radio wave absorption characteristics.

In the above embodiment, a ferrite board was formed by using a synthetic resin (epoxy resin) instead of cement as a binder to obtain a radio wave absorber having a similar structure. The size and gap size of the ferrite board are the same.
However, a compound obtained by mixing 15 parts by weight of ferrite with respect to 1 part by weight of the synthetic resin was used. In this way, a radio wave absorber for TV ghost countermeasures showing excellent radio wave absorption performance in the VHF band was obtained.

When actually used as an exterior material of a high-rise building, the structure is as shown in FIG. 3, for example. A plurality of ferrite boards 42 formed in a strip shape with a compound in which ferrite grains and cement are mixed are arranged such that a plurality of ferrite boards 42 are arranged at equal intervals in the width direction with a gap therebetween.
Is fixed to the base with a fitting (not shown) or the like. An exterior decorative material such as a decorative tile 50 is provided on the front side of the ferrite board 42, and a lightweight concrete 52 is cast on the rear side to integrate the whole into a radio wave absorbing wall. Reinforcing reinforcing bars and the like are incorporated in the lightweight concrete 52. Here, the decorative tile 50 has a structure in which a protruding portion 50 a having a shape conforming to the gap dimension is provided on the back surface side, and the protruding portion 50 a is a joint portion with the lightweight concrete 52. Alternatively, as shown in FIG. 4, the projecting portion 50b on the back surface side of the decorative tile 50 is made small, and the lightweight concrete 52 is inserted into the gap, and is fixed to the lightweight concrete 52 at the projecting portion 50b. Is also good. These are configurations in which an inorganic material enters the gap. In any case, it is mounted on the wall of a high-rise building so that a gap is provided in the direction of the electric field when viewed from the arrival direction of the television wave.

Such a radio wave absorbing wall can be manufactured, for example, by the following method. The decorative tiles are arranged in the panel form so that the back side faces upward. In the case of the structure as shown in FIG. 3, the protruding portion is also used as a mold for a ferrite board, and in the case of the structure as shown in FIG. 4, a mold for a ferrite board is separately arranged, and ferrite grains and cement are mixed. The compound is supplied and formed into a strip shape to form a ferrite board. A metal perforated plate is placed on it and assembled. If necessary, fix the ferrite board to the metal perforated plate with metal fittings. Reinforcing reinforcement is placed above it, and lightweight concrete is poured. Lightweight concrete integrates the whole, including ferrite boards and decorative tiles. Alternatively, a ferrite board may be separately formed in advance, and the ferrite boards may be arranged and attached to a metal reflector. The mounting structure and the manufacturing method may be appropriately changed depending on the materials used.

FIG. 5 is a sectional view showing another embodiment of the radio wave absorbing wall. A ferrite board 62 molded into a strip shape with a compound of ferrite grains and cement,
A plurality of sheets are arranged so as to be arranged at equal intervals in the width direction with a gap 64 therebetween, and are fixed to a reinforcing bar 66 assembled in a lattice shape by a fitting or the like. An exterior plate such as a decorative tile 70 is disposed on the front side of the ferrite board 62, and fixing hooks 71 are protruded to the back side deeply through the gap 64. And lightweight concrete 6 on the back side
2 is cast and the whole is integrated to form a radio wave absorbing wall. Reinforcing reinforcing bars 73 are embedded in the lightweight concrete 72. The decorative tile 70 includes a hook-shaped fixing hook 71.
Is fixed by being embedded in the lightweight concrete 72, and the gap 64 remains as a void.

[0025]

As described above, the present invention is a radio wave absorber panel and a radio wave absorption wall in which large ferrite boards are arranged with a gap therebetween and fixed to a metal reflector. The cost can be reduced and good radio wave absorption characteristics in a wide band can be obtained as compared with the method using a single layer of ferrite mortar. Further, according to the present invention, the magnetic permeability and the dielectric constant can be controlled by the gap, and a TV ghost prevention measure can be taken not only for the VHF band but also for the UHF band.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a radio wave absorber panel according to the present invention.

FIG. 2 is a perspective view showing another embodiment of the radio wave absorber panel according to the present invention.

FIG. 3 is a partial perspective view showing one embodiment of a radio wave absorbing wall according to the present invention.

FIG. 4 is a partial perspective view showing another embodiment of the radio wave absorbing wall according to the present invention.

FIG. 5 is a sectional view showing still another embodiment of the radio wave absorbing wall according to the present invention.

FIG. 6 is an explanatory view showing the structure and dimensions of a radio wave absorber panel according to the present invention.

FIG. 7 is a characteristic diagram showing the effect of the mixing ratio of ferrite grains.

FIG. 8 is a characteristic diagram showing an effect of a gap ratio.

FIG. 9 is a characteristic diagram showing an effect of a gap ratio.

FIG. 10 is a characteristic diagram showing the effect of the thickness of the ferrite board.

FIG. 11 is a characteristic diagram showing an effect of a gap ratio.

FIG. 12 is a characteristic diagram showing the effect of the thickness of the ferrite board.

FIG. 13 is a characteristic diagram showing the radio wave absorption performance of an example of the product of the present invention.

FIG. 14 is a characteristic diagram showing radio wave absorption performance of another example of the product of the present invention.

[Explanation of symbols]

 Reference Signs List 20 radio wave absorber panel 22 ferrite board 24 gap 26 metal plate

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor: Manabu Teranishi 5-36-11 Shimbashi, Minato-ku, Tokyo Inside Fuji Electric Chemical Co., Ltd. (72) Masayuki Inagaki 5-36-11 Shimbashi, Minato-ku, Tokyo Fuji Inside Electrochemical Co., Ltd. (72) Inventor Makoto Ishikura 5-36-11 Shimbashi, Minato-ku, Tokyo Fuji Electric Chemical Co., Ltd. (72) Hideo Tanaka 1-25-1 Nishishinjuku, Shinjuku-ku, Tokyo Taisei Construction Co., Ltd. (72) Inventor Wignaraja Shiva Kumaran 1-25-1, Nishi Shinjuku, Shinjuku-ku, Tokyo Taisei Construction Co., Ltd. (72) Inventor Tetsuo Yamada 1-25-1, Nishi Shinjuku, Shinjuku-ku, Tokyo Taisei Construction Corporation (72) Inventor Yukio Kosaka 3-1-2, Yoyogi, Shibuya-ku, Tokyo Showa Mining Co., Ltd. (72) Inventor Akira Matsuyama 891 Yamaki, Ichihara-shi, Chiba -5

Claims (8)

[Claims] 1. A radio wave in which a plurality of strip-shaped ferrite boards are fixed to a metal reflector so as to be arranged at equal intervals in the width direction with a gap therebetween by a compound in which ferrite grains and a binder are mixed. Absorber panel. 2. The sum of the gap dimensions is 3 to 3 times the total panel width.
The radio wave absorber panel according to claim 1, wherein the radio wave absorber panel is set to 7% and used for measures against VHF band television ghost. 3. The sum of the gap dimensions is set to 15 times the total panel width.
The radio wave absorber panel according to claim 1, wherein the radio wave absorber panel is used for measures against UHF band television ghost. 4. The ferrite board has a thickness of 20 to 40 mm.
The radio wave absorber panel according to claim 2 or 3, wherein 5. The radio wave absorber panel according to claim 1, wherein the gap is filled with a filler made of concrete or synthetic resin. 6. The sum of the gap dimensions is 3 to 3 times the total panel width.
The radio wave absorber panel according to claim 5, which is set to 30%. 7. The ferrite board has a thickness of 20 to 50 mm.
The radio wave absorber panel according to claim 6, wherein 8. An exterior decorative material is provided on the front side of the radio wave absorber panel according to claim 4 or 7, and lightweight concrete is cast on the metal reflector on the back side to integrate the whole into a plate shape.
A radio wave absorbing wall in which the gaps are arranged in the direction of the electric field when viewed from the direction of arrival of television radio waves.