JP2000209023A - Radio wave absorbing panel structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a frequency band wide and to improve radio wave absorption characteristics by arranging ferrite absorbers of specified width and thickness continuously in the magnetic field direction of coming radio waves and at a prescribed gap rate in the electric field direction and specifying the dielectric constant of first and second calcium silicate plates. SOLUTION: A calcium silicate plate 2 having the dielectric constant from 5 to 15 is stuck and arranged on the bottom of an aluminum case 1. On the calcium silicate plate 2, a ferrite plate 3 having width A from 15 to 40 mm and thickness B from 5 to 10 mm is continued in the magnetic field direction and arranged at an interval in the electric field direction. A calcium silicate plate 4 is arranged in the dielectric direction of the ferrite plate 3 and fixed by an adhesive agent together with the ferrite plate 3. At this time, the gap rate of the dielectric direction is made into 40 to 55%. The width of the ferrite plate 3 is made wider than 15 mm for reducing the deformation at the time of sintering, the width is made narrower than 40 mm for reducing a reflection loss over wide band and the electric field gap rate is made into 40 to 55% for matching.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a radio wave absorbing panel for a glass curtain wall 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.

As one of the structures of the outer wall of this high-rise building, there is a glass curtain wall. In this glass curtain wall structure having a radio wave absorbing wall, a glass-air layer, a radio wave absorber, and a reflector are arranged in this order from the surface of the wall. For the radio wave absorber, a ferrite plate is mainly used as a radio wave absorber, and various structures for arranging and fixing the ferrite plate have been proposed.

FIG. 9 shows a sectional view of a conventional example. In this conventional example, the ferrite plate 51 is sandwiched between calcium silicate plates 52 to fix the ferrite plate. FIG. 10 shows how the ferrite plates 51 are arranged. The ferrite plate 51 sandwiches the spacer 53 and is arranged continuously in the vertical direction and discontinuously in the horizontal direction. The glass 55 is arranged and fixed on the front surface via the air layer 54. As the ferrite plate 51, 100 mm × 10
A thin plate having a thickness of 0 mm and a thickness of 6 to 8 mm was used. In addition, the structural body of the wall played the role of the reflector.

[0005]

As a countermeasure against the ghost of television 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 are mainly in the UHF band. The broadband radio wave absorbers shared with the above are rarely seen. In particular, in a local area, the transmission points of television waves in the VHF band and the UHF band are often the same, and it has been difficult to obtain sufficient radio wave absorption characteristics with the conventional structure. Further, in the vicinity of the capital, the incoming radio waves of VHF and UHF have different incident angles from each other, and there is a demand for a radio wave absorbing wall capable of absorbing radio waves in a wide frequency band and radio waves having different incident angles.

The distance (spatial distance) between the glass curtain wall glass and the radio wave absorbing panel used for ordinary skyscrapers is about 80 to 100 mm, and the thickness of the glass is about 15 to 20 mm. It is used. Recently, high-strength glass and the like have been used to reduce
In order to prevent heat cracking of the glass, a panel having a structure with a space distance of 110 to 200 mm is used. Due to this change in the structure, it has been difficult for the conventional calcium silicate plate (with a dielectric constant of about 3 to 4) sandwiching the ferrite to satisfy the characteristics.

[0007] The present invention solves these needs and provides a VHF
It is an object of the present invention to provide a structure of a radio wave absorbing panel for a glass curtain wall capable of absorbing radio waves in a wide frequency band of UHF and radio waves having different incident angles.

[0008]

According to the present invention, there is provided a radio wave absorbing panel structure in which a glass-air layer, a first calcium silicate plate, a ferrite absorber, a second calcium silicate plate, and a reflector are arranged in this order. In the above, the ferrite absorber has a width (A) of 15 mm to 40 mm and a thickness (B) of 5 to
10 mm, and the ferrite absorber has a gap ratio of 40% in the direction of the magnetic field of the incoming radio wave continuously and in the direction of the electric field.
The first and second calcium silicate plates are arranged so as to have a dielectric constant of 5 to 15%.

The present invention is also a radio wave absorbing panel structure, wherein the first and second calcium silicate plates contain carbon powder, carbon fiber, or barium titanate powder. . As described above, the calcium silicate plate of the present invention is manufactured by filling carbon powder, carbon fiber, or barium titanate powder in the manufacturing process, thereby producing a special silicate having a dielectric constant of 5 to 15. A calcium plate can be obtained. This content can be appropriately set. In addition, the dielectric constant of the calcium silicate plate may be set to 5 to 15 by containing other components.

Further, the present invention is the radio wave absorbing panel structure wherein the distance between the ferrite absorber and the reflector is 10 mm to 35 mm.

Further, the present invention is the radio wave absorbing panel structure wherein the thickness of the first calcium silicate plate is set to 10 mm or less.

Further, according to the present invention, the spatial distance of the air layer is set to one.
A radio wave absorbing panel structure characterized in that the length is 20 mm or more.

In the present invention, the reflector may be a metal reflector such as an aluminum sheet, an aluminum plate or a stainless steel plate, and these may be fixed to the second calcium silicate plate by bonding or the like. Can be configured. Further, the reflector is constituted by a metal box form as described above, and a second calcium silicate plate-a ferrite absorber-a first calcium silicate plate is laminated in this order from the bottom surface of the box form. Then, it can also be configured by bonding and fixing, and integrating within the box form.

Further, the present invention provides the ferrite absorber,
It is arranged at intervals in the direction of the electric field, and at this interval, a dielectric constant similar to that of the first and second calcium silicate plates is 5 to 5.
15 calcium silicate plates are placed and there is no displacement,
It is preferable to make a firm fixation.

[0015]

FIG. 1 is a perspective view, partially in section, of a first embodiment according to the present invention. In this embodiment, VHF 1 to 12 ch, UHF 14 and 16 transmitted from Tokyo Tower are used.
This is an example in which a radio wave absorbing panel is manufactured under a design condition of an incident angle of 10 ° with respect to radio waves of channel ch. This embodiment will be described. First, an aluminum case 1 of (width) 3000 × (length) 4000 × (depth) 45 mm is prepared. A dielectric constant of 9.2 and a thickness (in the direction B) of 30
mm calcium silicate plate 2 is attached and arranged. At this time, it is preferable to put a reinforcing material in the bottom of the aluminum case and reinforce it.

A ferrite plate 3 is arranged on the calcium silicate plate 2. The ferrite plate 3 has a width (A) of 25 mm, a thickness (B) of 9 mm, and a length (C) of 200 mm.
mm, and are continuous in the direction of the magnetic field of the arriving radio wave and are arranged at intervals in the direction of the electric field. A calcium silicate plate 4 having a dielectric constant of 6.0, a width of 20.5 mm, and a thickness of 9 mm is arranged between the ferrite plates 3 in the direction of the electric field, and is fixed together with the ferrite plate 3 with an epoxy adhesive. At this time, the gap ratio in the electric field direction is about 45%. It is preferable that the ferrite plates 3 are fixed in advance with a tape so that no gap is formed between the ferrite plates 3 in the magnetic field direction.

Next, a calcium silicate plate 5 having a dielectric constant of 9.2 and a thickness of 6 mm was adhered to the entire surface to produce a radio wave absorbing panel for a backboard. FIG. 2 is a sectional view of a glass curtain wall to which the radio wave absorbing panel for a backboard is attached. From the radio wave incident side, glass 7, air layer 6, first calcium silicate plate 5, ferrite plate 3,
Second calcium silicate plate 2, reflector (aluminum case)
It becomes 1.

The produced radio wave absorbing panel is 3 m high.
Is installed on the measurement stand of the rigid urethane block 14
Place a 0 mm square, place a glass (15 mm thick) on it, set the antenna angle to the specified incident angle of 10 °,
It was measured by the spatial standing wave measurement method. FIG. 3 shows the measurement results. As shown in FIG. 3, this embodiment has good return loss characteristics.

Next, a second embodiment according to the present invention will be described. Although the overall structure is partially different in dimensions,
This is the same as the embodiment. In this embodiment, the radio wave incident angle is 30 °.
This is an example in which a radio wave absorbing panel is manufactured for TV Kanagawa and Saitama as UHF bands under the design conditions of. This embodiment will be described. First, (width) 3000 x (length) 40
A calcium silicate plate 2 having a dielectric constant of 8.2 and a thickness of 30 mm is attached to the bottom of an aluminum case 1 having a size of 00 × (depth) 43 mm. On the calcium silicate plate 2,
Width (A) 20mm, thickness (B) 7.5mm, length (C)
The 200 mm ferrite plates 3 are arranged with an electric field gap of about 40%. A calcium silicate plate 4 having a dielectric constant of 8.2, a width of 13.3 mm, and a thickness of 7.5 mm is arranged between the ferrite plates 3 in the direction of the electric field, and is fixed together with the ferrite plate 3 with an epoxy adhesive. I have. Next, a dielectric constant of 8.
2. A 6 mm-thick calcium silicate plate 5 was attached to the entire surface to produce a radio wave absorption panel for a backboard.

The manufactured radio wave absorbing panel is 3 m high.
Is installed on the measurement stand of the hard urethane block 15
A 0 mm square was placed, glass (thickness: 15 mm) was placed thereon, and the antenna angle was set at a 30 ° incident angle, and measurement was performed by a time domain method. FIG. 4 shows the measurement results. As shown in FIG. 4, this embodiment has good return loss characteristics.

A third embodiment according to the present invention will be described. Although the overall structure is partially different in dimensions,
This is the same as the embodiment. This embodiment uses a radio wave incident angle of 45 °.
This is an example in which a radio wave absorbing panel is manufactured under the following design conditions. This embodiment will be described. First, (width) 3000x
(Length) 4000 x (depth) 30mm aluminum case 1
A calcium silicate plate 2 having a dielectric constant of 6 to 14 and a thickness of 20 mm is arranged at the bottom of the substrate. On the calcium silicate plate 2, a ferrite plate 3 having a width (A) of 40 mm, a thickness (B) of 6.5 mm, and a length (C) of 200 mm is applied with an electric field gap of about 40 mm.
Arrange in%. A dielectric constant of 6 to 14, a width of 26.7 mm, and a thickness of 6.5 mm are set between the directions of the electric field of the ferrite plate 3.
Is placed. Then, the dielectric constant 6
-14, 6 mm and 10 mm thick calcium silicate plate 5
Was set and temporarily placed to produce a radio wave absorption panel for a backboard.

The calcium silicate plate has a dielectric constant of 6,
8, 10, 12, and 14 were replaced to form a panel, and the radio wave absorption characteristics were measured. The measurement was carried out by placing two manufactured radio wave absorbing panels on a measuring stand having a height of 3 m, placing a 140 mm square block of hard foamed urethane, placing glass (thickness: 15 mm) thereon, and setting the antenna angle to 45 mm.
° Set at the angle of incidence and measured by the time domain method. FIG. 5 shows the result when the thickness of the first calcium silicate plate 5 is 6 mm, and FIG. 6 shows the result when the thickness is 10 mm.

In the present invention, as in the above embodiment, by combining a calcium silicate plate having a dielectric constant of 5 to 15 with the calcium silicate plate, it is possible to satisfy the radio wave absorption performance which has been difficult in the past. Was.

FIG. 7 is a perspective view of a fourth embodiment according to the present invention. This embodiment is an example in which a radio wave absorbing panel is manufactured under a design condition of an incident angle of 45 °. This embodiment will be described. This radio wave absorption panel is an example in which a (width) 1000 × (length) 1000 mm is configured.
A first calcium silicate plate 15 having a dielectric constant of 8 and a thickness (B direction) of 10 mm is set, and a ferrite unit is arranged on the first calcium silicate plate 15.

This ferrite unit has a width (A) of 40
A ferrite plate 13 having a thickness of (B) 6.5 mm and a length (C) of 200 mm is disposed at a gap ratio of about 40% in the direction of the electric field. 8. A calcium silicate plate 14 having a width of 26.7 mm and a thickness of 6.5 mm is arranged.

Next, a second calcium silicate plate 12 having a dielectric constant of 8 and a thickness of 20 mm was arranged, an aluminum sheet 11 was adhered thereon, and thermocompression bonded to produce a radio wave absorbing panel.

The 24 manufactured radio wave absorbing panels were placed on a measuring stand having a height of 3 m so as to be continuously connected in the direction of the magnetic field, and a rigid foamed urethane block of 140 mm square was placed thereon. 15 mm), the antenna angle was set at an incident angle of 45 °, and measurement was performed by a time domain method. FIG. 8 shows the measurement results. As shown in FIG. 8, this embodiment has good return loss characteristics. FIG. 8 also shows a case where the dielectric constant of calcium silicate is 3 for comparison with the prior art. It can be seen that the present invention can improve the radio wave absorption characteristics in the UHF band. As described above, by optimally selecting the dielectric constant of the calcium silicate plate, a radio wave absorbing panel corresponding to a broadcast frequency band can be configured.

In the present invention, when the dielectric constant of the calcium silicate plate is larger than 15, the frequency range in which the radio wave absorption performance of 14 dB or more is narrowed and the band becomes narrow, so that it becomes difficult in terms of manufacturing accuracy.

The thickness of the second calcium silicate plate of the present invention is preferably from 10 to 35 mm. This is because the thickness is 35
mm, the resonance frequency becomes 700M
This is because it is not possible to satisfy the reflection attenuation characteristic of 14 dB or more exceeding Hz and cannot be used. In the present embodiment, although no examination data with an incident angle of 46 degrees or more is provided, it has been confirmed by past experiments that as the incident angle increases, the reflection attenuation characteristics become better. The thickness of the second calcium silicate plate controls the distance between the ferrite absorber and the reflector.

The width of the ferrite plate is 15 to 40 mm.
Is preferred. The reason for this is that 15mm
In the following, deformation during sintering becomes large and is not economical. 40
mm or less in terms of propagation multiplier,
From the experimental results, the reflection loss characteristics could not satisfy the characteristics in a wide band. In addition, the thickness of the ferrite plate is 5 to 10 m.
The reason for defining the m and the electric field gap ratio to be 40 to 55% is that if the ratio is out of this range, the range where matching can be obtained from various experimental results is narrow and impractical.

When the thickness of the first calcium silicate plate is large, it is difficult to satisfy the reflection loss at 700 MHz ≦ 12 dB at an incident angle of 30 degrees. For this reason, the thickness of the first calcium silicate plate is preferably 10 mm or less. Regarding the thickness of the glass, 10-15mm
It has been confirmed that even when the thickness is reduced, the reflection attenuation characteristics are improved because the reflection of radio waves from the surface is reduced.

In the above embodiment, the length of the ferrite plate is set to 200 mm, but the purpose is to reduce the gap in the magnetic field direction at the joint surface of the ferrite plate. Absent. The ferrite plate was used with a length of about 600 mm (three sheets) fixed with tape. The length may be determined according to workability.

In the above embodiment, an aluminum sheet, an aluminum plate, a stainless steel plate, an aluminum case, or the like is used as the metal reflection plate. However, a metal material functioning as a reflection plate may be used.
The thickness and the like are not specified, and any material can be used as long as mechanical strength can be guaranteed.

In the present invention, the calcium silicate plate may be attached by a method in which the frame material and the ferrite are bonded or fixed with bolts or the like. There is no particular stipulation regarding the mounting method. This calcium silicate plate is for the purpose of aesthetic appearance and the purpose of preventing the ferrite plate from falling off. When high-frequency characteristics are regarded as important, the thickness may be adjusted to the extent possible.

In the radio wave absorbing panel of the present invention,
A refractory board (for example, a calcium silicate plate) may be attached to the back surface of the reflection plate. The fireproof board has a fireproof standard defined according to the mounting position of the radio wave absorbing panel, and is not necessarily required.
The reflector and the fireproof board may be fixed with screws and bolts. This part has no relation to the radio wave absorption 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 10 ° to 45 °.

[0037]

According to the present invention, it is possible to obtain a radio wave absorbing panel for glass curtain walls having good radio wave absorbing characteristics with respect to radio waves having a wide frequency band and different incident angles.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional perspective view of a first embodiment according to the present invention.

FIG. 2 is a sectional 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 partial characteristic diagram of a third embodiment according to the present invention.

FIG. 6 is a partial characteristic diagram of the third embodiment according to the present invention.

FIG. 7 is a perspective view of a fourth embodiment according to the present invention.

FIG. 8 is a characteristic diagram of a fourth example according to the present invention and a comparative example.

FIG. 9 is a sectional view of a conventional example.

FIG. 10 is a plan view showing an arrangement of ferrite plates in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aluminum case 11 Aluminum sheet 2,12 Second calcium silicate plate 3,13 Ferrite plate 4,14 Calcium silicate plate 5,15 First calcium silicate plate 6 Air layer 7 Glass

Claims (5)

[Claims] 1. Glass-air layer-first calcium silicate plate-ferrite absorber-second calcium silicate plate
In the radio wave absorbing panel structure arranged in the order of the reflector, the ferrite absorber has a width (A) of 15 mm to 40 mm.
mm, the thickness (B) is 5 to 10 mm, and the ferrite absorber is disposed so as to have a gap ratio of 40% to 55% continuously in the magnetic field direction of the arriving radio wave and in the electric field direction. A radio wave absorbing panel structure, wherein the first and second calcium silicate plates have a dielectric constant of 5 to 15. 2. The method according to claim 1, wherein the first and second calcium silicate plates comprise carbon powder, carbon fiber,
Alternatively, a radio wave absorbing panel structure containing barium titanate powder. 3. The radio wave absorbing panel structure according to claim 1, wherein a distance between the ferrite absorber and the reflector is 10 mm to 35 mm. 4. The radio wave absorbing panel structure according to claim 1, wherein the thickness of the first calcium silicate plate is 10 mm or less. 5. The radio wave absorbing panel structure according to claim 1, wherein the air layer has a spatial distance of 120 mm or more.