JP2000134032A - Radio wave absorption panel and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an absorber light in weight and also obtain the structure of a radio wave absorption panel corresponding to a wide band for both a VHF and a UHF by using a ferrite plate having specific width and thickness for the absorber. SOLUTION: In a radio wave absorption structure, exterior material, an absorber and a reflection are arranged in this order, and a ferrite plate 4 having 15 to 30 mm width and 4 to 8 mm thickness is used as the absorber. Also, ferrite plates are continuously arranged in the magnetic field direction of incoming radio waves, the magnetic field direction is preferably arranged with the interval of 45 to 60% interval ratio placed and a dielectric 5 that is below 2 of dielectric constant is preferably arranged at interval parts. It is possible to maintain the ferrite plates 4 at prescribed intervals and also to prevent concrete 7 including moisture from flowing in by arranging the dielectric 5. Also, the cladding preferably has a characteristic in which a dielectric constant is equal to or less than 5.0-J3.0 and its thickness is preferably in the range of 10 to 15 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio wave absorbing panel used for an outer wall of a high-rise building and for preventing unnecessary reflected radio waves.

[0002]

2. Description of the Related Art In recent years, unnecessary reflected radio waves from high-rise buildings have become obstacles to television broadcasting, and there has been a problem of radio wave pollution such as producing ghosts on television screens. As a countermeasure, there is a method of embedding a radio wave absorber in the outer wall of a high-rise building. As this radio wave absorber, a ferrite plate is mainly used, and various radio wave absorption walls in which these magnetic materials are embedded have been proposed.

FIG. 6 shows the structure of this conventional example. The radio wave absorbing wall is obtained by disposing a ferrite plate 52 on the back surface of an exterior tile 51 and integrating it with a reflective reinforcing bar 53 by concrete 54. The ferrite plates 52 are arranged continuously in the direction of the magnetic field and at intervals in the direction of the electric field.
The ferrite plate 52 has a width of 100 mm and a thickness of 6 mm.
A thin plate having a thickness of about 8 mm was used.

[0004]

As a countermeasure against the ghost of television radio waves, the adoption of radio wave absorbing walls in high-rise buildings is becoming popular, but most of them are mainly in the VHF band and the UHF band. The shared broadband radio wave absorber is rarely seen. Especially in local areas, TV radio waves (VHF / UHF)
In many cases, the transmission points are the same, and it was difficult to obtain sufficient radio wave absorption characteristics with the conventional structure. In the vicinity of the capital, the incoming radio waves of VHF and UHF have different incident angles, and a radio wave absorbing wall capable of absorbing radio waves in a wide frequency band and radio waves of different incident angles is demanded.

[0005] In particular, when a radio wave absorbing panel is manufactured by the PC method, the water content at the time of concrete casting causes
The moisture content of the panel is high. As a result, the dielectric constant of the concrete portion was increased, which affected the radio wave absorption characteristics. If this moisture content is dried to about 1%, desired radio wave absorption characteristics can be obtained, but this drying requires a period of about two years or more. Thus, in the radio wave absorption panel by the PC method, the water content (dielectric constant) in the concrete is
Broadband characteristics were impaired.

SUMMARY OF THE INVENTION An object of the present invention is to provide a structure of a radio wave absorbing panel which can solve the above-mentioned requirements, can be reduced in weight, and can be used for both VHF and UHF.

[0007]

According to the present invention, there is provided a radio wave absorbing panel structure in which an exterior material, an absorber, and a reflector are arranged in this order, wherein the absorber has a width (A) of 15 mm to 30 mm and a thickness (B). 4) A radio wave absorbing panel using a 4 mm to 8 mm ferrite plate.

Further, in the present invention, the ferrite plate is continuously arranged in the magnetic field direction of the arriving radio wave, the electric field direction is arranged with an interval of 45 to 60%, and the dielectric constant is 2 or less in the interval. A radio wave absorption panel characterized by disposing the above dielectric. The exterior material has a dielectric constant of 5.
0-J0.3 or less, thickness 10mm-15
mm is a range of the radio wave absorption panel. Further, the distance between the absorber and the reflecting muscle is set to 10 to 2
This is a radio wave absorbing panel having a thickness of 5 mm.

Further, according to the present invention, a mold is set on a surface plate, an exterior material is disposed in the mold, a resin-based adhesive is applied on the exterior material, and then a magnetic component of an incoming radio wave is applied to the ferrite plate. And a dielectric having a dielectric constant of 2.0 or less is disposed in the space, and a resin adhesive is applied to a gap between the dielectric and the ferrite plate. And
A method for manufacturing a radio wave absorbing panel, comprising fixing a structure while preventing water from entering, placing a reflection / structural line at a predetermined position, and then placing concrete.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a radio wave absorbing panel structure in which an exterior material, an absorber, and a reflector are arranged in this order, wherein the absorber has a width (A) of 15 mm to 30 mm and a thickness (B).
A ferrite plate of 4 mm to 8 mm is used. Further, the ferrite plate is preferably arranged continuously in the direction of the magnetic field of the arriving radio wave, and the direction of the electric field is preferably arranged at intervals of 45 to 60% in the direction of the electric field. Preferably, a dielectric is provided. By arranging this dielectric, the ferrite plate can be maintained at a predetermined interval, and the concrete containing moisture can be prevented from flowing between the ferrites. It is also effective for weight reduction. Urethane foam, styrene, or the like can be used as the dielectric.

The exterior material of the present invention has a dielectric constant of 5.0-.
J0.3 or less, thickness is 10mm ~ 15mm
Is preferably within the range. Further, it is preferable that an interval between the absorber (ferrite plate) and the reflection streaks is 10 to 25 mm.

According to the present invention, 100 MHz to 800
In a wide band of MHz, it is possible to obtain a radio wave absorbing panel having good characteristics with a return loss of 15 dB or more.
This makes it possible to obtain a wide-band radio wave absorption panel compatible with both VHF and UHF. Further, according to the present invention, even when an incoming radio wave is obliquely incident on the radio wave absorption panel, a radio wave absorption panel corresponding to a wide range of incident angles can be obtained.

In the manufacturing method of the present invention, a mold is set on a surface plate, an exterior material is arranged in the mold, and a resin adhesive is applied on the exterior material. This resin-based adhesive is applied to the entire surface of the exterior material with a roller or the like to prevent water from entering. Then
The ferrite plate is arranged continuously in the direction of the magnetic field component of the arriving radio wave and is spaced apart in the direction of the electric field component. A dielectric having a dielectric constant of 2.0 or less is arranged in the space, and A resin adhesive is applied to the gap and fixed, and a structure is provided to prevent water from entering. After arranging the reflection / structural streaks at predetermined positions, concrete is cast to manufacture a radio wave absorbing panel.

According to the present invention, it is possible to obtain a radio wave absorbing panel made by a method of preventing entry of moisture which greatly affects the radio wave absorbing performance (between the exterior material and the back surface of the ferrite core).

A first embodiment according to the present invention will be described. In the first embodiment, the incident angle of the incoming radio wave is designed to be 32.5 degrees. FIG. 1 is a sectional view of the first embodiment, and FIG. 2 shows the arrangement of ferrite plates. In the first embodiment, a mold 2 (3200 × 4000 mm) is set on the surface plate 1, and a ceramic plate 3 (thickness 13 mm) is set in the mold 2. This ceramic plate 3 is jointed. And ceramic plate 3
A resin-based adhesive is applied to the entire back surface with a roller or the like to prevent water from entering.

Next, a ferrite plate 4 is arranged. The ferrite plate 4 has a width (A) of 25 mm and a thickness (B) of 8 m.
m, a ferrite plate having a length (C) of 200 mm was used.
The ferrite plate 4 was uniformly set with a porosity of 45% in the direction of the electric field (direction A in the figure), and was arranged such that no gap was formed in the direction of the magnetic field (direction C in the figure). The ferrite plates continuous in the direction of the magnetic field were connected by a resin tape of 25 mm. In addition, the width 20.5
A hard urethane foam 5 having a thickness of 8 mm and a thickness of 8 mm was set and fixed with an adhesive. Ferrite plate 4 to prevent water from entering
A resin adhesive was applied to the gap between the resin and the urethane foam 5.

After placing the reflection / structural streaks 6 at a uniform distance of 20 mm from the back of the ferrite plate 4, the concrete
And a radio wave absorbing panel was manufactured. FIG. 3 shows a result obtained by measuring the first embodiment by the time domain method at an incident angle of 32.5 degrees. As shown in FIG.
It shows good characteristics with a return loss of 15 dB or more in a wide band of 800 MHz.

A description will be given of a second embodiment according to the present invention. In the second embodiment, the incident angle of the incoming radio wave is designed to be 45 degrees. In the second embodiment, the ferrite plate 4 has the same structure as that of the first embodiment, and has a width (A) of 30 m.
A ferrite plate having a thickness of (m), a thickness (B) of 7 mm and a length (C) of 200 mm was used. The ferrite plates were uniformly set with a porosity of 45% in the electric field direction, and were connected with a 30 mm resin tape so that no gap was formed in the magnetic field direction. A hard urethane foam 5 having a width of 24.5 mm and a thickness of 7 mm was set in the gap, and fixed with an adhesive. In order to prevent water from entering, a resin-based adhesive was applied to the gap between the ferrite 4 and the urethane foam 5. After installing the reflection / structural streaks 6 at a uniform distance of 20 mm from the back of the ferrite plate 4,
Concrete 7 was cast to produce a radio wave absorbing panel.
Further, although the above-mentioned exterior material is 13 mm in thickness, an exterior material having a thickness of 15 mm was similarly set and manufactured similarly. FIG. 4 shows the return loss characteristics when the outer material is 13 mm and 15 mm. In each case, good characteristics with a return loss of 15 dB or more were exhibited in a wide band of 100 MHz to 800 MHz. In this case, the 13 mm-thickness exhibited better characteristics.

A third embodiment according to the present invention will be described. In the third embodiment, the incident angle of the incoming radio wave is designed to be 60 degrees. The third embodiment has the same structure as that of the first embodiment, and the ferrite plate 4 has a width (A) of 20 m.
A ferrite plate having m, thickness (B) 6 mm, and length (c) 200 mm was used.

Formwork 2 (3200 × 4000 m)
m), and after setting the ceramic plate 3 (15 mm) in the mold 2, a resin-based adhesive is roller-coated on the entire back surface of the ceramic plate 3.
The ferrite plate 4 was uniformly set thereon with an electric field direction porosity of 55%. In the direction of the magnetic field, a material connected by a 20 mm resin tape so as to prevent a gap from being used was used. A hard urethane foam 5 having a width of 24.45 mm and a thickness of 6 mm was set in the gap, and fixed with an adhesive. In order to prevent water from entering, a resin adhesive was applied to the gap between the ferrite plate 4 and the urethane foam 5. After placing the reflection / structural streaks 6 at a uniform distance of 25 mm from the back of the ferrite plate 4, the concrete
And a radio wave absorbing panel was manufactured. In addition, an exterior material (thickness: 20 mm) was similarly manufactured. Two radio wave absorbing panels were prepared for each condition, and the measurement results of the return loss characteristics are shown in FIG. As shown in FIG.
It shows good characteristics with a return loss of 15 dB or more in a wide band of 100 MHz to 800 MHz. In particular, excellent attenuation characteristics are obtained on the high frequency side.

In the embodiment of the present invention, the length (direction C) of the ferrite plate 4 is set to 200 mm, but the purpose is to reduce the gap at the ferrite rod joining surface in the direction of the magnetic field, and the length is specified. It does not do.

In the embodiment of the present invention, the size of the mold is 3200 mm in width × 4000 mm in length, but is not particularly limited. The required size differs depending on the size of the building PC, and may be determined accordingly.

In the present invention, the width of the ferrite plate is set to 15
mm to 30 mm, the thickness is 4 to 8 mm, and the electric field gap ratio is 45 to 60%. Various experimental results show that matching cannot be achieved outside this range, and that the reflection loss is 100 This is because the characteristics of 15 dB or more cannot be satisfied at up to 800 MHz. In addition, the dielectric constant of the dielectric disposed in the electric field gap portion is 2.0 or less, and the dielectric constant of the exterior material is 5.
A range of 0 to J0.3 or less and a thickness of 10 to 15 mm is also a preferable range for obtaining the above characteristics.

According to the present invention, as in the above embodiment, good radio wave absorption performance is exhibited even for radio waves obliquely incident on a wall surface having an incident angle of radio waves of 30 ° to 60 °.

[0025]

According to the present invention, it is possible to obtain a radio wave absorbing panel having good radio wave absorbing characteristics for radio waves having a wide frequency band and different incident angles. Further, the weight of the radio wave absorption panel can be reduced. Further, according to the present invention, it is possible to manufacture an inexpensive VHF / UHF compatible radio wave absorbing panel in the PC method, and manufacture a panel corresponding to any incident angle as a local property and a high-rise building radio wave absorbing panel around the Kanto area. It is possible to do.

[Brief description of the drawings]

FIG. 1 is a sectional view of a first embodiment according to the present invention.

FIG. 2 is a perspective view of a first embodiment according to the present invention.

FIG. 3 is a characteristic diagram of the first embodiment according to the present invention.

FIG. 4 is a characteristic diagram of a second embodiment according to the present invention.

FIG. 5 is a characteristic diagram of a third embodiment according to the present invention.

FIG. 6 is a structural view of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Surface plate 2 Formwork 3 Exterior material 4 Ferrite plate 5 Dielectric (urethane foam) 6 Reflection / Structure 7 Concrete

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Toshihiko Tanaka 70-2, Minamisakaemachi, Tottori City, Tottori Prefecture F-term in Hitachi Metals Co., Ltd. Tottori Plant 5J020 BD02 EA02 EA04 EA10

Claims (5)

[Claims] In a radio wave absorbing panel structure in which an exterior material, an absorber, and a reflector are arranged in this order, the absorber has a width (A) of 15 mm to 30 mm and a thickness (B) of 4 mm to 8 mm.
An electromagnetic wave absorption panel characterized by using a ferrite plate of the above. 2. The ferrite plate is continuously arranged in a magnetic field direction of an incoming radio wave, and an electric field direction has an interval ratio of 45 to 60%.
2. The radio wave absorbing panel according to claim 1, wherein a dielectric having a dielectric constant of 2 or less is arranged at the interval. 3. The exterior material has a dielectric constant of 5.0-J0.
3. The radio wave absorbing panel according to claim 1, wherein the characteristic is 3 or less, and the thickness is in a range of 10 mm to 15 mm. 4. An interval between said absorber and said reflection streaks is 10
The thickness is set to about 25 mm.
The radio wave absorption panel described in. 5. A mold is set on a surface plate, an exterior material is disposed in the mold, a resin-based adhesive is applied on the exterior material, and then a ferrite plate is continuously applied in a direction of a magnetic field component of an incoming radio wave. And
Arranged at intervals in the direction of the electric field component, a dielectric having a dielectric constant of 2.0 or less is arranged at the interval, and a resin adhesive is applied to a gap between the dielectric and the ferrite plate, and fixed. A method for manufacturing a radio wave absorption panel, comprising: a structure for preventing water from entering; a reflection / structural streak disposed at a predetermined position;