JP3509936B2 - Radio wave absorber, precast concrete plate and curtain wall - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio wave reflector for television ghosts used in high-rise buildings and the like, a precast concrete plate and a curtain wall using the same.

[0002]

2. Description of the Related Art As a conventional countermeasure against television ghost, for example, Japanese Patent Publication No. 55-13600 and Japanese Patent Publication No. 55-49.
As disclosed in Japanese Patent Publication No. 798, the outer wall surface of a building such as concrete (a high-rise building) in which a radio wave reflector such as a reinforcing bar is buried is formed from a ferrite sintered body having excellent radio wave absorption characteristics in the VHF band and the UHF band. It is common practice to attach a large number of tiles.

Attempts have also been made to mix ferrite grains directly into the concrete wall surface.

[0004]

However, when the above-mentioned conventional ferrite sintered body tile is used, since the ferrite sintered body itself is very heavy, there is a problem in workability and safety of tile attachment. Occurs. Further, the tile of the ferrite sintered body has a planar shape of only about 100 mm square and is very small, so that there is a problem that the tile attaching work becomes very complicated.

On the other hand, in the case of the method in which the ferrite particles are mixed in the concrete constituting the wall surface, the electromagnetic wave absorption characteristic is worse than that in the case where the tile made of the ferrite sintered body is used, and the desired absorption was tried. If the thickness is 3
It requires about 0 cm, which makes it difficult to use for actual construction. On the other hand, JP-A-5-26
Japanese Patent No. 7879 proposes a radio wave absorber formed by stacking thin radio wave absorbers containing conductive fibers. In this product, a plurality of radio wave absorbers containing conductive fibers such as carbon fibers in a dielectric matrix such as mortar are stacked and lined with a conductive reflector made of aluminum. By arranging so that the dielectric constant of the side farther from the conductive reflector, that is, the one on the radio wave entrance side (front side) becomes smaller, it absorbs wideband radio waves such as television broadcasts and is a ghost. It suppresses reflected waves that cause obstacles such as.

[0006] In the case of this radio wave absorber, it is thinner and lighter than the conventional one in which a ferrite sintered tile is adhered or ferrite is directly mixed into concrete, and the construction is easy, but Since it is configured as a dielectric type electromagnetic wave absorber, there is a problem that it is difficult to reduce the total thickness to a certain extent or more from the viewpoint of electromagnetic wave absorption capability.

The present invention has been made in view of such a background, and an object thereof is a television ghost which has a large plane shape and can be thinned and has a good electromagnetic wave absorption characteristic. An object of the present invention is to provide an electromagnetic wave absorber suitable for the countermeasure and a product using the electromagnetic wave absorber.

[0008]

To achieve the above object, according to an aspect of, in the radio wave absorber according to the present invention, the surface side of the radio wave reflector such as a metal plate, the product layer a plurality of radio wave absorbing plate In the arranged wave absorber for television ghost, the wave absorber is made by mixing at least ferrite grains and a non-magnetic material, and the non-magnetic material is mortar or concrete.
, Or an epoxy resin, and the permittivity of the electromagnetic wave absorbing plate placed on the side closer to the electromagnetic wave reflector of the plurality of sheets is larger than the permittivity of other electromagnetic wave absorbing plates.
So that the radio wave placed on the side close to the radio wave reflector
The ferrite particles mixed in the absorption plate should not be Mn-Zn-based.
Which consists of a material with a relatively high dielectric constant,
The ferrite particles mixed in the electromagnetic wave absorption plate are
It is preferable to use a material having a relatively low dielectric constant such as Ni-Zn system.
I tried to make it. Alternatively, the surface of a radio wave reflector such as a metal plate
TV ghost pair with one radio wave absorber on the front side
In the electromagnetic wave absorbing material for the measures, the electromagnetic wave absorbing plate should be at least
Is a mixture of ferrite grains and a non-magnetic material.
The magnetic materials are mortar, concrete, and epoxy resin.
And the electric wave absorption plate is
Set the dielectric constant on the side near the wave reflector to be higher than the other dielectric constants.
As described above, the
The light particles are made of a material having a relatively high dielectric constant such as Mn-Zn system.
Ferrite grains that make up and are mixed into other parts
Has a relatively low dielectric constant such as Mg-Zn system or Ni-Zn system.
I made it with a good material

That is, as a concrete means for making the dielectric constants of a plurality of electromagnetic wave absorbing plates (hereinafter referred to as plate materials) different, a Mn-Zn-based material is provided in a plate material arranged on the side close to the electromagnetic wave reflector. with the incorporation of relatively high dielectric constant ferrite grains etc., the other plate member Mg-Zn-based, mixed relatively low dielectric constant ferrite grains such Ni-Zn system.

Further, in the electromagnetic wave absorber of the present invention, the mixing ratio of the non-magnetic material and the ferrite particles is 30 to 5% by weight.
The latter is 70 to 95% by weight, and the grain size of the ferrite grains is 0.1 mm to 0.8 × T (T is the thickness of the plate material). It should be noted that, in the plate material arranged on the side closer to the radio wave reflector, the high dielectric material may be 0.1 to 5% by weight with respect to the nonmagnetic material mixed in the predetermined ratio.

As described above, the mixing ratio of the ferrite particles to the non-magnetic material is set to 70 to 95% by weight. When the amount is less than 70% by weight, the electromagnetic wave absorption characteristic is deteriorated, and when the amount is more than 95% by weight, the nonmagnetic material is set. It is difficult to mix with. Further, the ferrite grain size is set to 0.1 mm to 0.8 × T because when the diameter is smaller than 0.1 mm, the characteristics are deteriorated and the plate thickness T
If it is larger than 80%, a part of the ferrite grains may be projected on the surface of the plate material. Further, the reason why the content of the high dielectric constant material is set to 0.1 to 5% by weight is that the radio wave absorption characteristics deteriorate outside the range.

By satisfying these conditions, it becomes possible to form a thin plate material having a plate thickness of 1 to several cm. When the plate thickness is other than the above, or when three or more layers are stacked, the thickness is appropriately adjusted as necessary. The precast concrete plate of the present invention relates to a precast concrete plate in which a radio wave reflector such as a reinforcing bar or a metal plate is embedded, and at least the concrete on one side of the embedded radio wave reflector is made of a non-magnetic material. It is a precast concrete board having a radio wave absorbing function, which is made of mortar and is constructed as the radio wave absorbing board of the present invention.

[0013] curtain wall of the present invention, in a housing at least one surface is made of a radio wave reflecting material such as aluminum in the apertured predetermined shape, a radio wave absorbing panel of the present invention, with respect to the opening of the high dielectric constant side The back, which is the direction away from the opening
It is a curtain wall having a radio wave absorbing function, which is installed on the side , that is, on the radio wave reflector side .

[0014]

The electromagnetic wave absorbing material of the present invention is not limited to simply mixing one kind of ferrite particles into the non-magnetic material, but changing the kind of the mixed ferrite particles, or if necessary, the carbon particles are placed at appropriate positions. By mixing a high-dielectric material such as fiber, the dielectric constant of the plate material attached to the radio wave reflector differs depending on the location, and more specifically, the dielectric constant on the side closer to the radio wave reflector becomes higher. Thereby, it is possible to reliably absorb the radio wave in the radio wave absorber.

In addition, since such a radio wave absorber can have a larger planar shape than a conventional ferrite sintered body tile, and has a thinner wall thickness than that obtained by mixing only ferrite grains into concrete, it is manufactured. And it can be easily attached to an actual building. In addition, when the configuration of the electromagnetic wave absorber of the present invention is applied to a precast concrete (PC) plate or a curtain wall, the TV ghost is automatically prevented by attaching them to the wall surface of the building by a normal construction method. You get a wall.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the electromagnetic wave absorber according to the present invention and the precast concrete board and curtain wall using the same will be described in detail with reference to the accompanying drawings. Figure 1
Shows an example of a radio wave absorber according to the present invention as a first embodiment, in which a first plate member 2 having the same plane shape is arranged on one side of a metal plate 1 which is a radio wave reflector. The second plate member 3 is arranged on the surface of the first plate member 2.
That is, in this example, a plurality of (two) first and second plate members 2 and 3 are arranged in layers.

The first plate member 2 arranged on the metal plate 1 side is
It is formed by mixing epoxy resin, which is a non-magnetic material, Mn—Zn ferrite particles, and carbon fiber, which is a high dielectric material. Specifically, a predetermined amount of ferrite particles (the mixing ratio of the epoxy resin and the ferrite particles is 15:85 by weight) in the epoxy resin and 1 for the epoxy resin.
The epoxy resin was cured in a state where the weight% of carbon fiber was mixed to prepare a rectangular plate material having a predetermined shape, that is, a thickness of 1.5 cm. In this case, the mixed ferrite particles having a particle size within the range of 0.1 to 10 mm are used.

The second plate material 3 is treated in the same manner as the first plate material 2 except that carbon fibers are not mixed, and the epoxy resin (15% by weight) is treated with Mn-Z.
The n-type ferrite particles (85% by weight) were mixed to form substantially the same shape and thickness. The dielectric constant ε of the first plate material 2 thus obtained was 150, and the dielectric constant ε of the second plate material 3 was 15.

Here, the mixing ratio (X% by weight) of ferrite grains in the present invention and carbon fiber (high dielectric material such as)
The difference from the mixing ratio (Y% by weight) will be described. That is, the mixing ratio X% by weight of the ferrite particles means that the total weight of the ferrite particles and the resin (nonmagnetic material) is 100% by weight.
And the ratio. In this case, even if the carbon fiber or the like is contained, the weight thereof is not included. Therefore, the remainder obtained by subtracting the weight of the mixed ferrite grains from the total weight becomes the resin weight. On the other hand, Y weight% of carbon fiber is the amount with respect to the weight of resin, and has a different meaning and definition from the weight% in terms of the mixing ratio of the above ferrite particles and resin (the same applies hereinafter). .

Further, in the present invention, it is possible to mix in a composition other than the above two or three compositions,
The weight of such contaminants is not taken into consideration in the composition ratio of the radio wave reflecting material of the present invention. The radio wave reflecting material of this example having the above-described structure has the characteristics shown in FIG. 2 regarding the relationship between the magnetic permeability μ and the frequency. This shows the characteristics for each plate material, and the first plate material 2 and the second plate material 3 have the same characteristic results. However, μ ′ in FIG. 2 represents a real part and μ ″ represents an imaginary part.

Regarding the relationship between the radio wave absorption characteristics (reflection loss RL) with respect to the frequency, as shown in FIG.
It was possible to maintain high absorption characteristics over a wide range extending from the HF band of 90 to 220 MHz or higher. It should be noted that in FIG. 3, what is shown by a broken line is a radio wave absorption characteristic with respect to a frequency of a conventional one having a plate thickness of 30 cm formed by directly containing ferrite grains in concrete.

As is apparent from FIG. 3, the radio wave reflecting material of the present invention is good in both the frequency range in which radio waves can be absorbed and the maximum level. In addition, the total thickness is as thin as slightly over 3 cm, compared with the conventional thickness of 30 cm. In the case of a radio wave reflection material formed by directly incorporating ferrite grains into conventional concrete, the radio wave absorption characteristics are further deteriorated as shown in FIG. 3 when the wall thickness is reduced.

In this embodiment, carbon fibers are not mixed in the second plate material 3, but carbon fibers may be mixed therein. However, even if carbon fibers are mixed, the dielectric constant of the first plate member 2 is adjusted to be higher. In that case, it is preferable that the mixing amount of the carbon fibers mixed in the second plate member 3 is, for example, about 0 to 0.3% by weight based on the weight of the resin.

In the above embodiment, the epoxy resin is used as the non-magnetic material mixed in the first plate material 2 and the second plate material 3. However, the non-magnetic material is not limited to this, and the resin may be of any kind. . Further, even if another material such as rubber or concrete is used instead of resin, the characteristic for electromagnetic wave absorption is equivalent as long as it is a non-magnetic material (dielectric constant should be almost the same), and it is similar to the above embodiment. The effect of is obtained.

Further, the high dielectric material is not limited to carbon fiber, but various materials such as carbon powder, metal fiber, permalloy and steel can be used. Further, in the present invention, instead of mixing the high dielectric material such as carbon fiber, the material of the ferrite grains mixed in each of the plate materials 2 and 3 is changed so that the first plate material 2 located on the metal plate 1 side is changed. It is also possible to increase the dielectric constant of. That is, for example, the first plate member 2 is replaced with the epoxy resin 15
Wt% and Mn-Zn ferrite particles having a high dielectric constant of 85% by weight, and the second plate member 3 is made of epoxy resin 15% by weight.
And 85% by weight of Mg-Zn ferrite particles having a low dielectric constant. The electromagnetic wave absorber configured in this way also obtained substantially the same characteristics as those shown in FIGS.

The ferrite particles used are not limited to those described above, Ni-Zn ferrite particles can be used instead of Mg-Zn system, and other appropriate materials can be used. The above mixing ratios and the like are merely examples, and for example, the ferrite particles mixed in each of the plate materials 2 and 3 are the same as 85% by weight, but it is not always necessary to match the mixed ferrite amounts of both. In addition, the mixing ratio with the resin can be appropriately changed.

Even when the mixing ratio of the ferrite particles to the plate materials 2 and 3 is changed as described above, a small amount of a high dielectric material such as carbon fiber may be mixed into the plate material. In that case, the plate material in which the high dielectric material is mixed may be on the first plate material 2 side, or, conversely, may be mixed only in the second plate material 3 (dielectric constant of the second plate material 3). If it is low, a small amount is mixed to increase the dielectric constant by a predetermined amount). Alternatively, an appropriate amount may be mixed into both the plate materials 2 and 3, and any method can be adopted for mixing the high dielectric material.

Further, as a modification of the first embodiment, the following structure can be adopted. That is,
The electromagnetic wave absorber of the first embodiment is composed of a plurality of (two) plate members 2 and 3 made of a non-magnetic material, whereas in the modified example, one piece of non-magnetic material such as concrete or resin is used. A magnetic material is used. High dielectric materials such as ferrite particles and carbon fibers are mixed in the one non-magnetic material plate in the same predetermined ratio as above, but the mixing ratio of the high dielectric materials is not uniform, but metal plates, etc. The vicinity of the radio wave reflector 1 is raised. As a result, the inside of the non-magnetic material made of one plate material is divided into a plurality of areas having different permittivities, and as a result, a configuration equivalent to that using a plurality of plate materials is obtained.

[Experimental Results] Next, the effects of the present invention will be described with reference to the measurement results of Experiments 1 to 8 in which the parameters are variously changed with respect to the relationship of “frequency-reflection loss”. Experiment 1 (change in ferrite content): Inventive product 1: First plate material (metal plate side) Epoxy resin 15% by weight + Mn-Zn ferrite grains (particle size 0.1 to 7 mm) 85% by weight + carbon Fiber 3 wt% (ratio to epoxy resin) Second plate material Epoxy resin 15 wt% + Mn-Zn ferrite grains (particle size 0.1 to 7 mm) 85 wt% Plate thickness is 1.5 cm Comparative Example 1: The ferrite particles are mixed in the first and second plate materials in an amount of 65% by weight (35% by weight of resin), and the other configurations are the same as those of the product 1 of the present invention.

The "frequency-reflection loss" measurement results of the product 1 of the present invention and the comparative example 1 are shown in FIG. Due to the difference in configuration between the two, in the product 1 of the present invention, high reflection loss was obtained over a wide frequency range as shown by the solid line in FIG.
In the case of No. 1, the reflection loss is low in a narrow band as shown by the broken line. -Experiment 2 (change in ferrite grain size): Invention product 1: Same as Experiment 1.

Comparative Example 2: The same as the composition of Inventive Product 1 except that ferrite particles having a grain size of 0.01 to 0.05 mm mixed in both the first and second plate materials were used. The "frequency-reflection loss" measurement results of the product 1 of the present invention and the comparative example 2 are shown in FIG. Due to the difference in configuration between the two, FIG.
Although a high reflection loss was obtained over a wide frequency range as indicated by the solid line, in Comparative Example 2, as shown by the broken line, the reflection loss is narrow and the reflection loss is low.

Experiment 3 (change in amount of carbon fiber): Inventive product 1: Same as Experiment 1. Comparative Example 3: The same as the configuration of the product 1 of the present invention except that the amount of carbon fibers mixed in the first plate material was 0.05% by weight (weight of resin). Comparative Example 4: The amount of carbon fiber mixed in the first plate material was 7
The composition is the same as that of the product 1 of the present invention except for the weight% (weight of resin).

"Frequency-" between the product 1 of the present invention and Comparative Examples 3 and 4
The measurement result of "reflection loss" is shown in FIG. Due to the difference between the two configurations, in the product 1 of the present invention, a high reflection loss was obtained over a wide frequency range as shown by the solid line in FIG. As shown by the one-dot chain line, each of them has a narrow band and the reflection loss is low.

Experiment 4 (Change in plate thickness 1): Inventive product 1: Same as in Experiment 1, the total thickness is 3.0
cm. Invention product 2: Same as the invention product 1 except that the total thickness is 2.0 cm. Invention Product 3: Same as Invention Product 1 except that the overall thickness was 4.0 cm. Invention Product 4: Same as Invention Product 1 except that the overall thickness was 5.0 cm.

The thickness of each plate in the products 1 to 4 of the present invention was made equal. Comparative Example 5: Total thickness 1.5 cm (first plate material 0.5c
m, the second plate material 1.0 cm), and the other configurations are the same as those of the product 1 of the present invention. Comparative Example 6: Total thickness of 6.0 cm (first plate material 4.5c
m, the second plate material is 1.5 cm), and the other configurations are the same as those of the product 1 of the present invention.

FIG. 7 shows the measurement results of "frequency-reflection loss" of the products 1 to 4 of the present invention and Comparative Examples 5 and 6. Due to the difference in the respective configurations, in the products 1 to 4 of the present invention, a high reflection loss was obtained over a wide frequency range as shown by the solid line to in FIG. 7, but the products of Comparative Examples 5 and 6 are shown by the broken line. It has a narrow band and low reflection loss.

Experiment 5 (Change in plate thickness 2): The thickness of the first plate member on the metal side was fixed to 1.5 cm, and the plate thickness of the second plate member was 0.2 cm in the range of 1 to 2 cm. The measurement of "frequency-reflection loss" was performed for 6 types of samples having the same configurations as those of the product 1 of the present invention except for the above. The result is shown in Fig. 8.
It was shown to. It was confirmed that good characteristics were obtained in all cases.

On the contrary, when the thickness of the second plate was fixed and the thickness of the first plate was changed in the same manner to measure the reflection loss characteristics, the same result as above was obtained. -Experiment 6 (dielectric constant): Comparative product: first in invention product 1
The configurations of the plate material and the second plate material were reversed. That is, the second
The carbon material was mixed with the plate material of (1) and the carbon fiber was not mixed with the first plate material, so that the first plate material on the metal side had a dielectric constant of 15 and the second plate material had a dielectric constant of 150.

The "frequency-reflection loss" measurement result of the sample is shown in FIG. As is clear from the figure, the predetermined frequency band (VHF band of 90 MHz or more)
It was confirmed that the sufficient reflection loss effect was not exhibited in. Experiment 7 (comparison with single layer): 1st in the present invention product 1
For a sample composed of a plate made of the same material as the above plate (which is a uniform mixture of carbon fibers) and a metal plate only (the plate is a single layer), the thickness of the plate was changed, and the change in reflection loss with respect to frequency was changed. It was measured. The result is shown in FIG.
It shows in (A).

Similarly, the thickness of the plate material was changed for the sample composed of the same plate material as the second plate material (without carbon fiber) and the metal plate only (the plate material is a single layer) in the product 1 of the present invention. The change in the reflection loss with respect to the frequency was measured. The result is shown in FIG. Figure 1
As is clear from 0 (A) and (B), it was confirmed that in any case, a sufficient reflection loss effect was not exhibited in the predetermined frequency band.

Experiment 8 (Ferrite grain): Mn—Zn type ferrite grain was used for the ferrite grain mixed on the first plate side, and Mg was used for the ferrite grain mixed on the second plate side.
-Samples were prepared using the Zn system, and the above experiments 1, 2, 4
The same experiment as in ~ 6 was performed. However, carbon fibers were not mixed into the first plate material side as in the above experiments.

In Experiment 8, the same "frequency-reflection loss characteristic" as in each of the above experiments was obtained. Figure 11
Shows a second embodiment of the present invention. In this example, a two-layer structure electromagnetic wave absorber is used as a precast concrete (P
C) It is applied to a plate.

That is, in this case, the reinforcing bars 10 assembled in a grid pattern are used as the radio wave reflectors, and the reinforcing bars 10 are embedded in the concrete 11 to manufacture the PC board 12. Then, as shown in the figure, the inside of the concrete 11 that constitutes the PC board 12 is located in the vicinity A on one side of the reinforcing bar 10.
According to the case of the product 1 of the present invention in the above experiment, desired ferrite grains 13 and carbon fibers 14 are mixed in a predetermined amount. Further, ferrite grains 13 are mixed in the surface side portion B. That is, in this example, the part A near one side corresponds to the first plate member in the radio wave reflecting material of the present invention,
The front surface side portion B corresponds to the second plate material. Furthermore, concrete 1 on the side where such ferrite particles are mixed
1 constitutes the non-magnetic material of the present invention.

With such a structure, the PC board of this embodiment is provided on the wall surface of the building as having a function of absorbing the electric wave for the TV ghost, which is the same as the construction of a normal PC board. be able to. Such a PC board 12 can be mass-produced in a factory,
Moreover, since the size thereof is in the unit of several meters, it is larger than the tile of the conventional ferrite sintered body and the construction is easy.

In this embodiment, the concrete 11 mixed with the non-magnetic ferrite particles is arranged on only one side of the reinforcing bar 10, but it may be arranged on both sides. Since it is not necessary to distinguish the front and the back from the ones arranged on both sides, there is an advantage that the workability is further improved and the electromagnetic waves generated in the room can be effectively absorbed. FIG. 12 shows a third embodiment of the present invention.

In this embodiment, a two-layered electromagnetic wave absorber is applied to a curtain wall, that is, in this case, an aluminum casing 20 having one side opened as a radio wave reflector is used. The first plate member 21 (resin + ferrite particles + carbon fiber) is arranged on the first side, and the second plate member 22 (resin + ferrite particles) is arranged on the surface side thereof.
Further, in this embodiment, the decorative plate 23 is arranged on the surface side of the second plate member 22. Then, the peripheries of these three plates are covered with the inner peripheral surface of the aluminum casing 20, and only the surface of the decorative plate 23 is exposed to the outside.

A mounting portion 24 is formed on the back surface side of the aluminum casing 20 in the same manner as an ordinary curtain wall, and is fixed to a predetermined position of a building through a bolt 25. Of course, the material of the housing is not limited to aluminum. With this configuration, the effect of the reflection loss with respect to frequency is as shown by the solid line in FIG. The broken line in FIG. 13 is a characteristic diagram of a radio wave absorber having a configuration using a conventional ferrite tile.

Also in the case of the curtain wall of this embodiment,
As with the second embodiment, it can be installed on the wall surface of a building without any difference from the construction of a normal curtain wall, as having a radio wave absorbing function for TV ghost. Such a curtain wall can be mass-produced in a factory, and since the size thereof is several meters, the curtain wall is larger than a conventional ferrite sintered tile and the construction is easy.

In each of the products having the electromagnetic wave absorbing function for television ghosts shown in the second and third embodiments, the amount of carbon fibers mixed in the plate material (or equivalent member) forming the two-layer structure is controlled. Although the dielectric constant of the plate material was changed by doing so, each product is configured using the plate material (or equivalent member) whose dielectric constant is changed by changing the type of ferrite particles mixed in, as described above. Of course it's okay.

Although each of the above-mentioned embodiments has a two-layer structure, the present invention is not limited to this and may have three or more layers. The case of the three-layer structure will be described. For example, as shown in FIG. 14, it is configured by stacking first, second, and third plate members 31, 32, and 33 in order from the metal plate 30 side. Each plate material has a basic structure of a mixture of a non-magnetic material and ferrite grains as in the case of each of the above-described embodiments, and is formed by mixing a predetermined amount of a high dielectric material into a predetermined plate material. To be done. However, also in this case, it is necessary to make the dielectric constant of the plate material (first plate material 31) on the side closer to the metal plate 30 higher than that on the far side.

By the way, the three-layered plate members 31, 32,
No. 33 has the same plate thickness, the same weight% of ferrite grains are mixed, and the dielectric constant is variously changed by adjusting the mixing amount of carbon fiber. Plate material> second plate material> third plate material in this order, the best results were obtained as shown in FIG. 15 (other arrangements did not give very good results). ). Such results were similarly good for those obtained by using different ferrite grains, and further by mixing different amounts of carbon fibers at appropriate positions while changing the different ferrite grains.

As shown in FIG. 15, the plate members 31, 3 are
The plate thicknesses of Nos. 2 and 33 are each 1 cm, 85% by weight of ferrite particles are mixed, and the dielectric constant is adjusted to 145 for the first plate member 31 and 65 for the second plate member 32 by adjusting the mixing amount of the carbon fibers. 3 shows the result of an experiment conducted using a radio wave absorber manufactured by adjusting the amount of carbon fibers so that the plate member 33 of 3 has 15.

[0053]

As described above, according to the first aspect of the present invention.
According to the radio wave absorber according to claim 3 , a plurality of plate materials (radio wave absorbers) formed by mixing ferrite grains of a magnetic material and a non-magnetic material are laminated on the surface side of a radio wave reflector such as a metal plate. or (claim 1) or single arrangement (claim 2), yet not only mixed uniformly one type of ferrite grains in the non-magnetic material, changing the ferrite grains of the type to be mixed, mixed into Ri changed ratio, or even by mixing a high dielectric material such as carbon fiber (claim 3) to a predetermined position, and larger than the other side dielectric constant of at least close to the radio wave reflector of the plate material. In this way, the mixture of ferrite particles of magnetic material and non-magnetic material was used as the radio wave absorber, and the dielectric constant on the side closer to the radio wave reflector was made higher, so that the radio wave absorber can be reliably absorbed. It is possible to obtain the effect that good reflection loss can be obtained for a wide range of frequencies for TV ghost.

Further, since it is a magnetic type electromagnetic wave absorbing material containing ferrite grains and has a high electromagnetic wave absorbing ability, it can be made thin and lightweight and has a flat surface per piece as compared with a conventional ferrite sintered body tile. Since the shape can be increased to several meters per side, it is easy to manufacture, and moreover, it can be easily attached to a building or the like and the workability is high.

Further, according to the precast concrete board according to claim 4 of the present invention and the curtain wall according to claim 5 , by applying the structure relating to the radio wave absorber of the present invention to the precast concrete board or the curtain wall. The effect that the TV ghost prevention wall can be easily obtained by simply attaching them to the wall surface of the building by a normal construction method without requiring any special construction method.

[Brief description of drawings]

FIG. 1 is a side view showing a first embodiment of a radio wave absorber according to the present invention.

FIG. 2 is a characteristic diagram showing the relationship between magnetic permeability and frequency.

FIG. 3 is a diagram showing a reflection loss characteristic with respect to a frequency of a radio wave absorber according to the present invention in comparison with a conventional one.

FIG. 4 is a diagram showing an experimental result for demonstrating the effect of the present invention.

FIG. 5 is a diagram showing an experimental result for demonstrating the effect of the present invention.

FIG. 6 is a diagram showing an experimental result for demonstrating the effect of the present invention.

FIG. 7 is a diagram showing an experimental result for demonstrating the effect of the present invention.

FIG. 8 is a diagram showing an experimental result for demonstrating the effect of the present invention.

FIG. 9 is a diagram showing an experimental result for demonstrating the effect of the present invention.

FIG. 10 is a diagram showing experimental results for demonstrating the effect of the present invention.

FIG. 11 is a partially cutaway perspective view showing an example of a PC board according to the present invention.

FIG. 12 is a side view showing an example of the curtain wall according to the present invention.

FIG. 13 is a frequency-reflection loss characteristic diagram thereof.

FIG. 14 is a side view showing another example of the radio wave absorber according to the present invention.

FIG. 15 is a frequency-reflection loss characteristic diagram thereof.

[Explanation of symbols]

1 Radio wave reflector (metal plate) 2 Radio wave absorption plate (first plate material) 3 Radio wave absorption plate (second plate material) 10 Radio wave reflector (rebar) 11 Electromagnetic wave absorption plate (concrete) 12 Precast concrete board 13 Ferrite grains 14 High dielectric material (carbon fiber) 20 Radio wave reflector (aluminum housing) 21 Radio wave absorption plate (first plate material) 22 Radio wave absorption plate (second plate material) 23 Veneer 30 Radio wave reflector (metal plate) 31 Radio wave absorption plate (first plate material) 32 Electromagnetic wave absorption plate (second plate material) 33 Radio wave absorption plate (third plate material)

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Miyazaki 1-25-1 Nishishinjuku, Shinjuku-ku, Tokyo Within Taisei Corporation (72) Inventor Hideo Tanaka 1-25-1 Nishishinjuku, Shinjuku-ku, Tokyo No.1 Taisei Corporation Ltd. (72) Inventor Wignaraja Shivakumaran 1-25-1 Nishishinjuku, Shinjuku-ku, Tokyo No.1 Taisei Corporation Ltd. (72) Inventor Kazuya Tanaka 1-25 Nishishinjuku, Shinjuku-ku, Tokyo No. 1 in Taisei Corporation (72) Inventor Tetsuo Yamada 1-25-1 Nishishinjuku, Shinjuku-ku, Tokyo Inside Taisei Corporation (72) Manabu Teranishi 5-36 Shinbashi, Minato-ku, Tokyo No. 11 Fuji Electric Kagaku Co., Ltd. (72) Inventor Masayuki Inagaki 5-36-1 Shimbashi, Minato-ku, Tokyo No. 11 Fuji Electric Kagaku Co., Ltd. (72) Makoto Ishikura 5-3 Shimbashi, Minato-ku, Tokyo No. 6-11 Fuji Denki Kagaku Co., Ltd. (72) Inventor Masao Kosaka 2-14-2 Nagatacho, Chiyoda-ku, Tokyo Inside Showa Mining Co., Ltd. (72) Inventor Zengo Ninomiya 12 Yawata Kaigan Dori, Ichihara, Chiba Prefecture (56) Reference JP-A-4-163998 (JP, A) JP-A-58-127400 (JP, A) JP-A-3-217082 (JP, A) JP-A- 1-241199 (JP, A) Actually open 4-28497 (JP, U) Actually open 60-48294 (JP, U) Actually open 55-64114 (JP, U) Actually open 2-95294 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H05K 9/00 E04B 1/92 E04B 2/94

Claims (5)

(57) [Claims] 1. A radio wave absorber for television ghosts, comprising a plurality of radio wave absorbers laminated on the front side of a radio wave reflector such as a metal plate, wherein the radio wave absorber comprises at least ferrite grains and a non-magnetic material. The non-magnetic material is any one of mortar, concrete, and epoxy resin, and the dielectric constant of the radio wave absorber disposed on the side closer to the radio wave reflector of the plurality of sheets. A material having a relatively high dielectric constant, such as Mn-Zn system, containing the ferrite particles mixed in the radio wave absorbing plate arranged on the side closer to the radio wave reflector so as to have a higher dielectric constant than other radio wave absorbing plates. And the ferrite particles to be mixed in another radio wave absorber are made of a material having a relatively low dielectric constant such as Mg-Zn system or Ni-Zn system , and the non-magnetic material
And the mixing ratio of the ferrite particles is 30 to 5% by weight.
% Of the latter is 70 to 95% by weight, and the ferrite is
The grain size is 0.1 mm or the thickness T of the electromagnetic wave absorbing plate.
On the other hand, 0.8 × T, which is a radio wave absorber. 2. A radio wave absorber for a television ghost, wherein one radio wave absorber is arranged on the front surface side of a radio wave reflector such as a metal plate, wherein the radio wave absorber has at least ferrite grains and a non-magnetic material. The mixed material, the non-magnetic material is one of mortar, concrete, and epoxy resin, and the radio wave absorber has a dielectric constant on the side close to the radio wave reflector larger than other dielectric constants. So that the ferrite grains mixed on the side close to the radio wave reflector are
In addition to being composed of a material having a relatively high dielectric constant such as an n-Zn system, the ferrite grains mixed in other parts are Mg-Zn.
Consists of materials with a relatively low dielectric constant such as Ni-based and Ni-Zn-based
And mixing the non-magnetic material with the ferrite grains
The former is 30 to 5% by weight and the latter is 70 to 95% by weight.
And the grain size of the ferrite grains is 0.1 mm to
A radio wave absorber, wherein the thickness of the radio wave absorber is 0.8 × T with respect to T. To wherein the radio wave absorbing plate, according to claim 1 or claim wherein the ferrite grains separately, characterized in that mixed carbon, a high dielectric material comprising at least one of metal fibers, as well as permalloy The radio wave absorber according to any one of 2 . 4. A precast concrete plate in which a radio wave reflector such as a reinforcing bar or a metal plate is embedded, at least one surface side of the embedded radio wave reflector according to any one of claims 1 to 3 . A precast concrete plate for electromagnetic wave absorption, characterized in that an electromagnetic wave absorption plate made of mortar, which is a non-magnetic material, is arranged. 5. The radio wave absorber according to claim 1 in a housing made of a radio wave reflective material such as aluminum having a predetermined shape with at least one surface opened, and the side having a higher dielectric constant is opened.
The curtain wall is characterized in that the curtain wall is arranged so as to be placed on the back side which is a direction away from the opening with respect to the mouth .