JP3117117B2 - Broadband radio wave absorption 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 broadband radio wave absorbing wall for a building material used for a wall surface of a building as a measure for preventing a radio wave reflection of a building such as a TV ghost.

[0002]

2. Description of the Related Art Conventionally, as disclosed in Japanese Patent Publication No. 55-49798, a radio wave absorbing wall for preventing TV ghosts is provided with ferrites arranged continuously in a magnetic field direction and at regular intervals in an electric field direction. The structure is fundamental. As shown in FIGS. 10 and 11, such a basic radio wave absorbing wall is formed by coupling the ferrite plate 1 so as to be continuous in the direction of the magnetic field of the radio wave and discontinuous in the direction of the electric field. A structure in which a ferrite plate 1 is continuously coupled in a magnetic field direction of a radio wave and a structure in which a ferrite plate 1 is continuously bonded in a magnetic field direction as shown in FIGS. In this arrangement, the ferrite plate 1 is fixed to a metal plate 2 serving as a radio wave reflector with a holding plate 3 and bolts 4 in a discontinuous arrangement (second conventional example).

Further, in practice, as shown in FIGS. 14 and 15, a surface finishing material such as an exterior tile is attached to the surface of the ferrite plate using the space in the direction of the electric field of the ferrite plate, and concrete is driven into the ferrite plate. A precast curtain wall structure in which the space between the plates and the back of the ferrite plate is filled with concrete is used.
14 and 15 show a radio wave absorbing wall (third conventional example) structured to be fixed with an exterior tile with special feet (porcelain tile or the like) 11 as a measure for preventing the ferrite plate 1 from falling. In this case, The ferrite plate 1 is continuously provided in the direction of the magnetic field on the front surface of the reinforcing bar 10 forming a metal reflection mesh (radio wave reflector).
The precast concrete plate radio wave absorption wall is formed by arranging the exterior tile 11 with special feet on the front surface of the ferrite plate 1 and placing concrete 12 on the rear surface side so as to be discontinuous in the direction of the electric field.

FIG. 1 shows the radio wave absorption characteristics of the first and second conventional examples which are the basic structure of the radio wave absorption wall shown in FIGS.
6 is indicated by the dotted line. It shows excellent radio wave absorption characteristics over a wide frequency range from VHF to UHF. Here, it is assumed that the incoming radio wave is perpendicularly incident on the wall surface, the thickness D of the ferrite plate 1 is 9 mm, and the gap ratio is {B / (A + B)} × 100 =
33 (%), where A is the length of the ferrite plate 1 in the direction of the electric field, and B is the gap between the ferrite plates in the direction of the electric field.

However, the radio wave absorbing wall used as the outer wall of the building is actually made of a combination of ferrite, concrete and an exterior material as shown in the third conventional example in FIGS. The radio wave absorption characteristics are degraded due to the characteristics (permittivity), thickness, and the like. Even if the conventional technology is designed in consideration of these constraints, the characteristics shown by the solid line in FIG. The incoming radio wave is assumed to be vertically incident on the wall surface, and the thickness D1: 20 mm of the lightweight concrete between the reinforcing bar 10 and the back surface of the ferrite plate 1 is assumed.
The thickness D2 of the ferrite plate 1 was 9 mm, the thickness D3 of the exterior tile in front of the ferrite plate was 15 mm, and the gap ratio was 33%. ). However, at present, the majority of TV ghost disorders are V
It is limited to the HF band, and at present, even such characteristics as shown by the solid line in FIG. 16 sufficiently contribute to practical use.

[0006] On the other hand, information transmission by TV is becoming more and more useful, and its use as a media medium in local communities, for example, a metropolitan television in Tokyo is planned. The use of the low frequency band of 400 MHz is planned.

As a result, TV ghost countermeasures in the 400 MHz to 500 MHz band have come to be taken up as an important issue in conjunction with the conventional TV broadcasting of the Open University of Japan. In response to the demands of such an era, the radio wave absorption wall using ferrite, that is, the radio wave absorption characteristics of the ferrite radio wave absorption wall is at least 10 dB up to the 500 MHz band.
The above return loss has been required.

[0008]

[Problems to be Solved by the Invention] UH of Future TV Radio Waves
In response to the increasing demand for F-band demand, development of a new ferrite radio-absorbing wall for TV ghost countermeasures that has excellent radio-absorbing characteristics over a wide frequency range from the UHF band as well as the VHF band is a major issue. .

The decisive factor in solving this problem is (1) In order to approximate the characteristic of the original ferrite electromagnetic wave absorbing wall shown by the dotted line in FIG. It is necessary to solve two technical issues: elucidation and resolution of the technical factors that affect it, and (2) radical review of ferrite as a radio wave absorber.

In summary of the results of the research so far, many improvements have been made to ferrite materials, and the characteristics have been improved accordingly. However, for example, in FIG. 14 and FIG.
At present, the radio wave absorption wall structure for building materials shown in the conventional examples, which is used practically, has not been able to reproduce the original radio wave absorption characteristics of ferrite materials, and has not led to the improvement of the characteristics as a radio wave absorption wall at present. is there. The essential cause is considered to be the change in the electromagnetic properties due to the integration with concrete.

The present invention pays particular attention to the dielectric properties of ferrite, which has been hardly noticed in the past, and comprises a ferrite plate discontinuously arranged in the electric field direction of an incoming radio wave and a substance (such as concrete) penetrating between the ferrite plates. By examining how the effective dielectric constant of the ferrite-containing layer changes due to concrete integration, and by examining the change in electromagnetic wave absorption characteristics due to changes in the dielectric properties of the ferrite-containing layer, the electromagnetic absorption characteristics of the concrete-integrated structure are improved. The purpose is to clarify the structural issues to be exerted and to solve those issues.

An object of the present invention is to appropriately set the effective dielectric constant of a ferrite-containing layer composed of a ferrite plate discontinuously arranged in the direction of the electric field of an incoming radio wave and a substance or a void entering between the ferrite plates. An object of the present invention is to provide a wide-band radio wave absorption wall capable of realizing sufficiently good radio wave absorption characteristics over a wide frequency range from a VHF band to a UHF band.

[0013] Other objects and novel features of the present invention will become apparent in the embodiments described later.

[0014]

In order to achieve the above object, the broadband radio wave absorbing wall according to claim 1 of the present application has a ferrite plate which is arranged continuously in the magnetic field direction of an incoming radio wave and discontinuously in the electric field direction. When the ferrite plate is fixed to concrete or mortar, the ferrite is discontinuous in the direction of the electric field.
The components between the plates are made of a material other than ferrite,
The effective dielectric constant of the ferrite- containing layer made of the substance between the sheet plate and the ferrite plate is set to 5 or less as viewed from the direction of the electric field.

The broadband radio wave absorbing wall according to claim 2 of the present application
Blow continuously in the direction of the magnetic field of the radio wave and discontinuously in the direction of the electric field
A ferrite plate is placed on a concrete or
When it is fixed to
Part of the components between the ferrite plates
Outside material and the rest of the concrete or
And a ferrule between the ferrite plates.
In the direction of the electric field of the ferrite-containing layer made of the constituent member
The effective permittivity is set to 5 or less. Application
The broadband radio wave absorption wall according to claim 3 is the same as that in claim 1 or 2.
The front of the ferrite plate in the direction of radio wave arrival
Specially covered with concrete or mortar or exterior material
It is a sign. The broadband radio wave absorbing wall according to claim 4 of the present application is
In Claim 3, the exterior material is the concrete or the concrete.
Have a foot or shear connector integrated into the
It is characterized by. A broadband radio wave absorbing wall according to claim 5 of the present application.
The spacer according to claim 2, wherein the space has a hollow structure.
It is characterized by being formed inside. Application
The broadband radio wave absorption wall according to claim 6 is the method according to claim 4, wherein
Characterized in that the gap is constituted by the cavity of the foot
I have.

[0016]

The electromagnetic wave absorbing wall using ferrite is designed with attention paid to the magnetic characteristics, and the TV ghost preventing electromagnetic wave absorbing wall is also designed so that the magnetic characteristics of the ferrite are not impaired, as is clear from FIGS. Considering the polarization plane of the radio wave, they are arranged continuously in the magnetic field direction of the radio wave. That is, the magnetic properties of the ferrite are kept continuous. On the other hand, an interval is provided in the direction of the electric field of the radio wave. As a result, the apparent dielectric constant of the ferrite, which is not so much considered in the conventional design, naturally changes due to the anti-electric field.

As shown in FIG. 10 or 12, when a perfect reflector, for example, a metal body is disposed on the back of a ferrite as a radio wave absorber, the surface input impedance of the ferrite is given by the following equation.

(Equation 1) The question is how close the value of the expression (1) is to the free space impedance, and how the value is satisfied within a wide frequency range below a certain value. When the thickness d of the ferrite is fixed, the frequency characteristic of the magnetic permeability and the frequency characteristic of the dielectric constant of the ferrite are important. Conventionally, the dielectric constant of ferrite has almost no frequency characteristics, and is treated as a constant value (about 10), and the design has been performed mainly by focusing on the frequency characteristics of magnetic permeability.

In the present invention, the difference between the basic structure shown in FIGS. 10 and 13 and the practical structure shown in FIGS. 14 and 15 is as follows.
Attention was paid to concrete between ferrites in the direction of the electric field, and factors affecting the ferromagnetic properties of ferrites were examined. When the space is filled with air and a material having a certain dielectric constant, such as concrete, the dielectric constant of the uniform layer changes when considered as a uniform layer from the viewpoint of a mixed dielectric. It is thought that. Therefore, in the present invention, a ferrite plate as a radio wave absorber and a ferrite-containing layer made of a void or a substance between the ferrite plates were considered, and the effect of the effective dielectric constant of the ferrite-containing layer on radio wave absorption characteristics was examined.

FIG. 17 shows a concrete integrated radio wave absorbing wall structure as shown in FIG. 14 and FIG.
Of the lightweight concrete between the steel and the back of the ferrite plate 1
1:20 mm, thickness D2 of ferrite plate 1: 9 mm, thickness D3: 1 on the front side of ferrite plate of exterior tile such as porcelain tile
The relationship between the effective dielectric constant and the frequency bandwidth having a return loss of 10 dB or more and 15 dB or more when the effective dielectric constant of the ferrite-containing layer is changed under the conditions of 5 mm and a gap ratio of 33% is shown. However, the curve (a) has a return loss of 10
A curve (b) indicates a frequency bandwidth having a return loss of 15 dB or more, respectively. As a result of FIG. 17, when the material and the thickness of the ferrite were constant, it became clear that the smaller the effective permittivity of the ferrite-containing layer, the wider the frequency bandwidth and the wider the bandwidth. 10d from VHF to UHF 500MHz band
To ensure a return loss of B or more, the return loss is 1
A bandwidth of 400 MHz or more is required as a frequency bandwidth having 0 dB or more, and the effective dielectric constant must be at least 5 or less, and preferably 4 or less, as seen from the curve (a) in FIG. In the current concrete-integrated radio wave absorbing wall, the ferrite gap is filled with concrete, and the effective dielectric constant of the ferrite-containing layer is about 7 or so. Therefore, in order to realize the effective permittivity of 5 or less, some measure for reducing the effective permittivity is required.

In the present invention, the anti-electric field coefficient is determined by the gap ratio [FIG.
When A and B shown in FIG. 1 are used, {B / (A + B)} × 10
0 (%)] (exponentially increasing with a slight increase in the gap ratio).
Focusing on the fact that the larger the difference between the dielectric constant of the gap and the dielectric constant of the ferrite, the larger the anti-electric field coefficient, the air layer, low dielectric constant material (specifically, the dielectric constant) Of a ferrite plate and a ferrite-containing layer composed of voids or a substance between the ferrite plates, the effective dielectric constant of the ferrite plate is reduced to 5 or less, and the outer wall material is used as an outer wall material. Has realized a wideband radio wave absorption wall that can be used sufficiently.

[0021]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a broadband radio wave absorbing wall according to the present invention.

FIG. 1 shows a first embodiment of a broadband radio wave absorbing wall according to the present invention, and shows a plan view of a concrete-integrated broadband radio wave absorbing wall. In this figure, 20 is a hollow extruded concrete plate (or mortar plate),
In order to insert and hold the ferrite plate 1, a plurality of hollow portions 21 penetrating (continuous) in the magnetic field direction of incoming radio waves (direction perpendicular to the plane of FIG. 1) are provided at intervals in the electric field direction of incoming radio waves. It is a hollow extruded product. The ferrite plate 1 used here is, for example, a square of 100 mm × 100 mm and a ferrite tile shape having a thickness of 9 mm. The ferrite plate 1 is inserted and fixed in each hollow portion 21 so as to be continuous in the magnetic field direction of the incoming radio wave. At this time, the width of the hollow portion 21 in the direction of the electric field is larger than the dimension of the ferrite plate 1 in the direction of the electric field. 22. Therefore, the ferrite plate 1
Containing a ferrite-containing layer (indicated by phantom line 25) comprising a gap in the direction of electric field between the ferrite plate and the electric field (a void 22 and the remaining concrete portion), the effective dielectric constant of the ferrite-containing layer 25 viewed from the direction of the electric field. Can be set to 5 or less. The ferrite plate 1 in the hollow portion 21
A support rod 23 made of a non-magnetic material such as concrete is inserted and fixed in an intermediate concave portion 24 of the hollow portion 21 in order to press and fix each ferrite plate 1 so as to be in contact with the rear surface of the hollow portion 21 so as to be continuous in the magnetic field direction. On the back of the hollow extruded concrete plate 20, a radio wave reflector 2 such as a metal plate, a metal mesh,
6 are provided (integrated).

FIG. 2 shows a comparison between the radio wave absorption characteristics of the first embodiment of FIG. 1 and the radio wave absorption characteristics of the conventional concrete-integrated radio wave absorption wall (third conventional example) of FIGS. 14 and 15.
However, it is assumed that the arriving radio wave is perpendicularly incident on the wall surface, and in both cases, the thickness D1: 20 mm of the lightweight concrete between the reinforcing bar 10 and the back surface of the ferrite plate 1 and the thickness D of the ferrite plate 1
The conditions were 2: 9 mm, the thickness D3 of the lightweight concrete or exterior tile in front of the ferrite plate was 15 mm, and the gap ratio was 33%. In the case of the first embodiment, 2C / B was 0.5. In the first embodiment, the return loss is at least 3 at 500 MHz, for example, as compared with the conventional radio wave absorption wall.
dB was improved, and good return loss characteristics of 12 dB or more were obtained.

As in the first embodiment of the present invention, the effective dielectric constant of the ferrite-containing layer 25 in the electric field direction is set to 5 or less by providing an air layer by the air gap 22 in a part of the gap between the ferrite plates 1 in the electric field direction. It is clear that the frequency bandwidth in which a sufficient return loss of 10 dB or more can be secured is widened.

FIG. 3 is a plan view of a second embodiment of the present invention, in which a precast curtain wall radio wave absorbing wall using a specially-fitted exterior tile (such as a porcelain tile) as a measure for preventing the fall of a ferrite plate is shown. In this case, the ferrite plate 1 is arranged on the front surface of the reinforcing bar 10 forming a metal reflection mesh (radio wave reflector) so as to be continuous in the direction of the magnetic field and discontinuous in the direction of the electric field.
On the front. Here, exterior tile 3 with special feet
The distance between the inner side surfaces of the feet 31a at both ends of the ferrite plate 1 is
Is sufficiently longer than the dimension in the direction of the electric field so that the width dimension C remains at both ends of the ferrite plate 1. Then, styrofoam 32 having a width of about 10 mm is buried in the width dimension C at both ends, and concrete (or mortar) 12 is cast and integrated on the back side of the ferrite plate 1, the special tile 31 with special feet and the styrofoam 32. ing. A support bar 33 made of a non-magnetic material such as concrete is provided at the time of concrete casting in order to press and fix each ferrite plate 1 in contact with the back surface of the ferrite plate 1 so as to be continuous in the magnetic field direction.

FIG. 4 shows a comparison between the radio wave absorption characteristics of the second embodiment shown in FIG. 3 and the radio wave absorption characteristics of the conventional concrete integrated radio wave absorption wall (third conventional example) shown in FIGS.
However, it is assumed that the arriving radio wave is perpendicularly incident on the wall surface, and in both cases, the thickness D1: 20 mm of the lightweight concrete between the reinforcing bar 10 and the back surface of the ferrite plate 1 and the thickness D of the ferrite plate 1
2: 9 mm, thickness D3 on the front side of the ferrite plate of the exterior tile
The conditions were 15 mm and a gap ratio of 33%, and 2C / B = 0.4 in the case of the second embodiment. In the second embodiment, for example, a return loss of 10 dB or more is secured at 500 MHz, and a wider band is achieved as compared with a conventional radio wave absorption wall.

As in the second embodiment of the present invention, the ferrite plate 1 and the styrofoam 32 are provided by providing the styrofoam 32 as a foam material having a dielectric constant of 2 or less at a part of the gap in the electric field direction between the ferrite plates. The effective dielectric constant of the ferrite-containing layer including the gap in the direction of the electric field can be set to 5 or less, and the frequency bandwidth in which a sufficient return loss of 10 dB or more can be secured can be widened.

FIG. 5 shows a third embodiment of the present invention, which is a plan view of a radio wave absorbing wall of a precast curtain wall using an exterior tile with a special foot (such as a porcelain tile). In this case, the ferrite plate 1 is arranged in front of the reinforcing bar 10 forming a metal reflection mesh (radio wave reflector) so as to be continuous in the magnetic field direction and discontinuous in the electric field direction.
On the front surface of the ferrite plate 1. Here, the exterior tile 41 with special feet has a foot 41a at one end, and a cavity 42 is formed inside the foot 41a.
And concrete (or mortar) 12 is cast and integrated on the back side of the ferrite plate 1 and the exterior tile 41 with special feet. A support bar 33 made of a non-magnetic material such as concrete is provided at the time of concrete casting in order to press and fix each ferrite plate 1 in contact with the back surface of the ferrite plate 1 so as to be continuous in the magnetic field direction.

According to the third embodiment, the special tile 4 with the special foot is provided in a part of the gap in the electric field direction between the ferrite plates.
The cavity 42 in one foot 41a is located, and the effective dielectric constant of the ferrite-containing layer composed of the ferrite plate 1 and the electric field direction gap including the cavity 42 (that is, the air layer) is set to 5
The frequency bandwidth in which a sufficient return loss of 10 dB or more can be secured can be widened.

In the third embodiment, the exterior tile 4
1 has a foot 41a in which a cavity 42 is formed only on one side, but it is also possible to adopt an exterior tile having a foot on which a cavity is formed on both sides.

FIG. 6 shows a fourth embodiment of the present invention, in which the shape of an exterior tile with a special foot (such as a porcelain tile) used as a measure for preventing a ferrite plate from falling is changed. That is, the exterior tile 31 with special feet of the second embodiment described above.
As compared with the above, the exterior tile 5 with special feet in the present embodiment
No. 1 has no step on the outer surface of the foot 51a at both ends, the width of the foot is small, and the width of both ends of the ferrite plate 1 on which the styrofoam 52 can be provided can be set large. The other configuration and operation and effect are the same as those of the above-described second embodiment.

FIG. 7 shows a plan view of a radio wave absorbing wall of a precast curtain wall using an exterior tile (porcelain tile or the like) with a shear connector according to a fifth embodiment of the present invention.
In this case, the ferrite plate 1 is disposed on the front surface of the reinforcing bar 10 forming a metal reflection mesh (radio wave reflector) so as to be continuous in the magnetic field direction and discontinuous in the electric field direction. On the front.
Here, the exterior tile 61 with a shear connector is integrated by inserting a shear connector 61a of metal or the like into the exterior tile main body, and the shear connector 61a extends in the rear direction of the exterior tile 61. Exterior tile 61
Of the ferrite plate 1 is sufficiently longer than the dimension of the ferrite plate 1 in the electric field direction. Then, concrete (or mortar) 1 is placed on the back side of the ferrite plate 1, the exterior tile 61 with a shear connector, and the styrofoam 62.
2 are cast and integrated. At this time, the shear connector 61a is buried in the concrete 12 and
Is prevented from falling. A support bar 33 made of a non-magnetic material such as concrete is provided at the time of concrete casting in order to press and fix each ferrite plate 1 in contact with the back surface of the ferrite plate 1 so as to be continuous in the magnetic field direction.

According to the fifth embodiment, the effective dielectric constant of the ferrite-containing layer composed of the ferrite plate 1 and the gap in the direction of the electric field including the polystyrene foam 62 can be set to 5 or less, and the sufficient return loss of 10 dB or more can be obtained. Can increase the frequency bandwidth that can be secured.

FIG. 8 shows a plan view of a radio wave absorption wall of a precast curtain wall using an exterior tile (porcelain tile or the like) with a shear connector according to a sixth embodiment of the present invention.
In this case, the structure of the exterior tile 61 with a shear connector is the same as that of the fifth embodiment, but the shape and arrangement of the styrene foam 72 are different. That is, in the sixth embodiment, all the gaps between the adjacent ferrite plates 1 in the electric field direction are filled with the styrene foam 72. Therefore, the effect of reducing the effective dielectric constant of the ferrite-containing layer is large. Other configurations, functions and effects are the same as those of the fifth embodiment.

FIG. 9 is a plan view of a seventh embodiment of the present invention showing a radio wave absorbing wall of a precast curtain wall using an exterior tile (such as a porcelain tile) with a shear connector.
In this case, the structure of the exterior tile 61 with a shear connector is the same as that of the fifth embodiment, but instead of arranging styrene foam at both ends of the ferrite plate 1, it is made of an inorganic material such as concrete, mortar, porcelain or an organic material such as plastic. A hollow spacer 82 having a hollow structure is embedded. In this case, since the inside of the spacer 82 remains as an air layer, the effect of reducing the effective dielectric constant of the ferrite-containing layer is large. Other configurations, functions and effects are the same as those of the fifth embodiment.

It should be noted that other organic or inorganic foam materials (for example, foam concrete) can be used in place of the styrene foam as the foam material used in the second embodiment and the like, and the effective dielectric constant of the ferrite-containing layer is reduced. It is desirable that the dielectric constant of the foamed material is 2 or less in order to lower it.

The exterior material may be a non-conductive non-magnetic material other than the exterior tiles shown in the second to seventh embodiments, and has another special shape for preventing the ferrite plate 1 from falling. It may be something.

Although the embodiments of the present invention have been described above, it is obvious to those skilled in the art that the present invention is not limited to the embodiments and various modifications and changes can be made within the scope of the claims. Would.

[0039]

As described above, according to the present invention,
A ferrite plate is arranged continuously in the magnetic field direction of the arriving radio wave and discontinuously in the direction of the electric field, and in a radio wave absorbing wall formed by fixing the ferrite plate to concrete or mortar, a gap or ferrite between the ferrite plate and the ferrite plate. Other than
Since the effective dielectric constant of the ferrite-containing layer made of the above-mentioned substance from the direction of the electric field is set to 5 or less, it is possible to realize a wide band of the radio wave absorption characteristics of the radio wave absorption wall. As a result,
UHF, which has been strongly demanded as a countermeasure for TV ghosts
A return loss of 10 dB or more is secured to the lower band side of the band, that is, the 500 MHz band, and the TV can support not only the VHF band TV broadcasting but also the 500 MHz band TV broadcasting of the Open University of Japan.
A ghost countermeasure radio wave absorbing wall can be provided.

[Brief description of the drawings]

FIG. 1 is a plan sectional view showing a first embodiment of a broadband radio wave absorbing wall according to the present invention.

FIG. 2 is a graph showing the frequency characteristic of return loss, comparing the radio wave absorption characteristics of the first embodiment and a conventional concrete-integrated radio wave absorbing wall (third conventional example).

FIG. 3 is a plan sectional view showing a second embodiment of the present invention.

FIG. 4 is a graph showing the frequency characteristic of return loss comparing the radio wave absorption characteristics of the second embodiment and the conventional concrete-integrated radio wave absorbing wall (third conventional example).

FIG. 5 is a plan sectional view showing a third embodiment of the present invention.

FIG. 6 is a plan sectional view showing a fourth embodiment of the present invention.

FIG. 7 is a plan sectional view showing a fifth embodiment of the present invention.

FIG. 8 is a plan sectional view showing a sixth embodiment of the present invention.

FIG. 9 is a plan sectional view showing a seventh embodiment of the present invention.

FIG. 10 is a plan view showing a first conventional example of a radio wave absorbing wall in which a ferrite plate is arranged continuously in a magnetic field direction and discontinuous in an electric field direction.

FIG. 11 is a front view of the same.

FIG. 12 is a plan view showing a second conventional example of a radio wave absorbing wall in which a ferrite plate is arranged so as to be continuous in a magnetic field direction and discontinuous in an electric field direction.

FIG. 13 is a front view of the same.

FIG. 14 is a perspective view showing a third conventional example of a radio wave absorption wall having a structure to be fixed with an exterior tile with special feet.

FIG. 15 is a plan sectional view of the same.

FIG. 16 is a graph showing the frequency characteristic of return loss comparing the radio wave absorption characteristics of the first and second conventional examples and the concrete-integrated radio wave absorbing wall (third conventional example).

FIG. 17 shows the effective dielectric constant and 10d of the ferrite-containing layer as viewed from the direction of the electric field in the concrete-integrated electromagnetic wave absorbing wall.
B is a graph showing a relationship with a frequency bandwidth at which a return loss of 15 dB or more is obtained.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ferrite plate 2 Metal plate 3 Holding plate 4 Bolt 10 Reinforcing bar 11, 31, 41, 51 Exterior tile with special feet 12 Concrete 20 Hollow extruded concrete plate 21 Hollow portion 22 Void 23, 33 Support rod 25 Ferrite containing layer 26 Radio wave reflection Body 31a, 41a, 51a Foot 32, 52, 62, 72 Styrofoam 42 Cavity 61 Exterior tile with shear connector 61a Shear connector 82 Spacer

Continuation of the front page (72) Inventor Yoshito Hirai 1-13-1 Nihombashi, Chuo-ku, Tokyo Inside TDK Corporation (56) References JP-A-53-24202 (JP, A) JP-A-1-241199 ( JP, A) JP-A-5-183331 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05K 9/00 E04B 1/92 E04B 2/94

Claims (6)

(57) [Claims] 1. A ferrite plate which is arranged discontinuously in a direction of an electric field on a radio wave absorbing wall in which a ferrite plate is disposed continuously in a magnetic field direction of an incoming radio wave and discontinuously in a direction of an electric field, and the ferrite plate is fixed to concrete or mortar. Blow the components between boards
Ferrite plate and the ferrite plate
A broadband radio wave absorption wall, wherein an effective dielectric constant of the ferrite-containing layer made of the substance between the layers is 5 or less as viewed from the direction of the electric field. 2. An electric field which is continuous in the magnetic field direction of an incoming radio wave and
A ferrite plate is placed discontinuously in the direction
For radio wave absorbing wall fixed to concrete or mortar
Then, some of the components between the ferrite plates discontinuous in the direction of the electric field
Materials other than voids or ferrite and the rest
The concrete or mortar is provided, and the ferrite plate and
Including the ferrite composed of the constituent members between the ferrite plates
The effective dielectric constant of the coated layer viewed from the direction of the electric field was set to 5 or less.
A broadband radio wave absorption wall characterized by the following . 3. The direction of arrival of a radio wave from the ferrite plate.
Cover the front with the concrete or mortar or exterior material
3. A broadband radio wave absorber according to claim 1, wherein
Wall. 4. The exterior material according to claim 1, wherein the concrete or the mol
Having a foot or shear connector integrated into the barrel
The broadband radio wave absorption wall according to claim 3, wherein 5. The method according to claim 1, wherein the gap is formed inside a spacer having a hollow structure.
The broadband radio wave absorption wall according to claim 2, wherein the wall is formed. 6. The method according to claim 6, wherein the gap is constituted by a cavity of the foot.
The broadband radio wave absorbing wall according to claim 4.