JP2000114864A - Radio wave absorbing panel structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio wave absorbing panel structure for a glass curtain wall having satisfactory radio wave absorbing characteristics to the radio waves over a wide frequency range in various incident angles. SOLUTION: The glass, an air layer, a radio wave absorber and a reflector are arranged in this order. In this case, as the structure of the radio wave absorber, a ferrite plate 2 having width A of 5 to 9 mm and thickness B of 15 to 22 mm is used, the ferrite plates are arranged with the gap plate of 70 to 84% in the electric field direction of coming radio waves and continuously in a magnetic field direction and the ferrite plates 2 are fixed in grooves on the bottom of a box-shaped metal case 1.

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. 6 is 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. 7 shows how the ferrite plates 51 are arranged. This ferrite plate 5
Numeral 1 sandwiches a 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.
The ferrite plate 51 has a width of 100 mm and a thickness of 6 mm.
A thin plate having a thickness of about 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 TV 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.

An object of the present invention is to provide a structure of a radio wave absorbing panel for a glass curtain wall which solves these needs.

[0007]

According to the present invention, there is provided a radio wave absorbing panel structure in which glass, air layer, radio wave absorber and reflector are arranged in this order, wherein the structure of the radio wave absorber has a width (A) of 5 to 5. A ferrite plate having a thickness of 9 mm and a thickness (B) of 15 to 22 mm was used.
% To 84%, and the direction of the magnetic field is a radio wave absorbing panel structure in which the ferrite plate is disposed continuously and the ferrite plate is fixed in a groove at the bottom of the box-shaped metal case.

Further, according to the present invention, the ferrite plate comprises two or more types of ferrite plates having different material properties, each having a thickness (B).
It has a structure that is laminated and integrated in the direction. At this time, it is preferable that the layers are stacked in ascending order of the magnetic permeability (μ ′) from the incident direction of the incoming radio wave. Further, it is preferable that the ferrite plates to be laminated be a combination having different lengths (C).

Further, the present invention is a radio wave absorbing panel structure in which a dielectric having a dielectric constant of 2.0 or less is disposed in the gap portion in the electric field direction.

Further, the present invention is a radio wave absorbing panel structure in which a decorative plate having a thickness of 10 mm or less is disposed on an upper surface of the ferrite. As this decorative board, a board having a dielectric constant of 3.2 or less is preferable.

[0011]

According to the present invention, a radio wave absorbing panel structure for a glass curtain wall has a width of 5 to 9 m.
The ferrite plate having a thickness of 15 to 22 mm and a gap ratio of 70% to 84% in the electric field direction of the incoming radio wave is arranged continuously in the magnetic field direction of the incoming radio wave. This ferrite plate is fixed to the groove at the bottom of the box-shaped metal case serving as the reflector,
By integrating them, a radio wave absorbing panel capable of absorbing radio waves with a wide frequency band and different incident angles is constituted.

According to the present invention, two or more types of ferrite plates having different material properties are used as the ferrite plate.
A good electromagnetic wave absorbing panel can also be obtained by using a laminate integrated in the thickness (B) direction. As the form of lamination of the ferrite plates, it is preferable that the ferrite plates are laminated in ascending order of the magnetic permeability (μ ′) from the incident direction of the incoming radio wave. Further, the ferrite plates to be laminated can be changed in length (direction C) to reduce the demagnetizing field at the joint surface so that no gap is generated in the direction of the magnetic field. Further, even when the ferrite plate is formed as a single layer, the same effects as described above can be obtained by forming the end faces in the length direction on the steps and arranging them in combination.

Further, according to the present invention, by disposing a material having a dielectric constant of 2.0 or less in the gap portion (between ferrite plates) in the electric field direction, the mechanical structure of the integrated structure can be maintained while maintaining the absorption characteristics. A panel with improved reliability can be obtained. As the material having a dielectric constant of 2.0 or less, urethane foam, styrene material and the like can be used.

According to the present invention, a decorative plate having a thickness of 10 mm or less can be arranged on the front surface of the ferrite plate stored in the box-shaped metal case. As the decorative plate, a material having a dielectric constant of 3.2 or less is preferable. For example, a calcium silicate plate can be used.

FIG. 1 is a partially sectional perspective view of a first embodiment according to the present invention. In this embodiment, the VHF radio wave incident angle 30
This is an example in which a radio wave absorbing panel is manufactured under the design conditions of 60 ° and a UHF radio wave incident angle of 60 °. This embodiment uses (width) 640
A box-shaped metal case 1 of 1 × (length) 1300 × (height) 35 mm is used. This box-shaped metal case 1 uses an aluminum plate material (thickness: 2 mm) and has a groove (pitch: 43.5) at the bottom.
mm) is formed. The box-shaped metal case 1 employs a grooved aluminum extruded member, and is formed by a method in which side surfaces are bonded. The ferrite plate 2 is arranged in the groove of the box-shaped metal case 1, fixed with an epoxy-based adhesive, and integrated. This ferrite plate 2
The upper ferrite plate 2a is a ferrite plate having a width (A) of 8 mm, a thickness (B direction) of 12 mm, and a length (C) of 180 mm, and has a complex magnetic permeability. μ ″ is 108 and tan δ is 3.
3, the lower ferrite plate 2b has a width (A) of 8 mm, a thickness (B direction) of 7 mm, and (C)
Direction) A ferrite plate of 200 mm, made of a MnZn-based material having a complex magnetic permeability μ ″ of 25 and a tan δ of 12.1.
Has a width (A) of 8 mm and a thickness (B) of 19 mm. The lengths of the ferrite plates 2a and 2b in the longitudinal direction are different from those of the upper and lower stages.

Then, the calcium silicate plate 3 (specific gravity 0.7 or less) cut to a prescribed size is inserted into the box-shaped metal case 1, and the ferrite plate 2, the box-shaped metal case 1 and the calcium silicate The plate 3 (thickness (B direction) 6 mm) was fixed with an adhesive to produce a radio wave absorbing panel.

In this embodiment, a ferrite plate 2 to be laminated is used.
The lengths of a and 2b are changed to reduce the gap in the magnetic field direction (the direction C in the figure) of the arriving radio wave. The ferrite plate 2 of this embodiment has a gap ratio of about 81.6% in the electric field direction (direction A in the figure) of the arriving radio wave, and the magnetic field direction is arranged continuously.

In the measurement of the radio wave absorbing panel of this embodiment, 27 manufactured panels were placed on a measuring stand having a height of 3 m, a block of hard foamed urethane (100 mm square) was placed, and glass (12 mm thick) was placed thereon. ) Was set, the antenna angle was set to a specified angle of incidence, and measurement was performed by a time domain measurement method. FIG. 3 shows the measurement results. As shown in FIG. 3, this embodiment has good return loss characteristics.

FIG. 2 is a perspective view, partly in section, of a second embodiment according to the present invention. In addition, the same code | symbol as FIG. 1 was used for the member of the same quality. This embodiment is an example in which a radio wave absorbing panel is manufactured under a design condition of a radio wave incident angle of 58 °. In this embodiment, (width) 640 x (length) 1300 x (height) 35 m
m box-shaped metal case 1 is used. This box-shaped metal case 1 uses an aluminum plate material (thickness 2 mm) and has a groove (pitch 47.25 mm) at the bottom. This box-shaped metal case 1 adopts a grooved aluminum extrusion member,
It is created by the method of laminating the sides. The ferrite plate 2 is arranged in the groove of the box-shaped metal case 1, fixed with an epoxy-based adhesive, and integrated. The ferrite plate 2 is formed by stacking two ferrite plates 2a and 2b. The upper ferrite plate 2a has a width (A) of 9 mm, a thickness (B direction) of 8 mm, and a length (C) of 18 mm.
0 mm ferrite plate with a complex magnetic permeability μ ″ of 53.
4, composed of a NiZn-based material having a tan δ of 1.08, the lower ferrite plate 2b is a ferrite plate having a width (A) of 9 mm, a thickness (B direction) of 9 mm, and a (C direction) of 200 mm, and has a complex magnetic permeability. μ ”is 86.6 and tan δ is 7.
5 NiZn-based materials. And, as a whole, the ferrite plate 2 has a width (A) of 9 mm and a thickness (B).
17 mm. Also, the ferrite plate 2a,
The length in the length direction of 2b is different from that of the upper and lower tiers.

Then, the calcium silicate plate 3 (specific gravity 0.7 or less) cut into a prescribed size is inserted into the box-shaped metal case 1, and the ferrite plate 2, the box-shaped metal case 1 and the calcium silicate The plate 3 (thickness (B direction) 6 mm) was fixed with an adhesive to produce a radio wave absorbing panel. Ferrite plate 2
In the gap part between, inject foaming filling of urethane resin,
Heat cured and filled with dielectric 4 (dielectric constant 1.4).
Thereby, the fixing of the ferrite plate 2 can be strengthened, and the reliability due to the vibration of the panel and the like is improved.

In this embodiment, the laminated ferrite plate 2
The lengths of a and 2b are changed to reduce the gap in the magnetic field direction (the direction C in the figure) of the arriving radio wave. The ferrite plate 2 of this embodiment has a gap ratio of about 84% in the direction of the electric field (direction A in the figure) of the arriving radio wave, and the direction of the magnetic field is arranged continuously.

In the measurement of the radio wave absorbing panel of this embodiment, 27 panels manufactured were placed on a measuring stand of 3 m in height, a block of hard urethane (110 mm square) was placed, and glass (20 mm thick) was placed on the block. ) Was set, the antenna angle was set to a specified angle of incidence, and measurement was performed by a time domain measurement method. FIG. 4 shows the measurement results. FIG. 4 shows a graph of the third embodiment at the same time. The third embodiment has the same structure as the second embodiment,
A ferrite plate 2 having a step size of 9 mm in width (A), 17 mm in thickness (B), and 200 mm in length (C direction) using a NiZn-based material for the lower ferrite plate 2b was used. It consists of. This figure 4
As shown in the figure, this embodiment has a good return loss characteristic.

A fourth embodiment according to the present invention will be described. The structure of the fourth embodiment is the same as that shown in FIG. The fourth embodiment is designed at a radio wave incident angle of 30 °. The pitch of the grooves of the box-shaped metal case 1 was 30.5 mm. The overall dimensions of the ferrite plate 2 were 9 mm in width (A) and 15 mm in thickness (B), and the laminated structure was composed of three stages. The upper ferrite plate has a width (A) of 9 mm and a thickness (B) of 5 m.
m, a ferrite plate having a length (C) of 80 mm and made of a NiZn-based material having a complex magnetic permeability μ ″ of 63.2 and a tan δ of 2.1. The middle ferrite plate has a width (A) of 9 mm and a thickness of 9 mm. (B) A ferrite plate having a length of 5 mm and a length (in the direction C) of 100 mm, made of a NiZn-based material having a complex magnetic permeability μ ″ of 101 and a tan δ of 3.5. The lower ferrite plate has a width (A) of 9 mm, (B) 5 mm, and a length (C direction).
80 mm ferrite plate with complex permeability μ ″ of 25, t
It was composed of a MnZn-based material having an δ of 12.1. Also,
In this example, the electric field gap ratio was about 70%, and the magnetic field direction was arranged so that no gap was formed at the joint surface.

In the measurement of the radio wave absorption panel of this embodiment, 27 panels manufactured were placed on a measuring stand having a height of 3 m, a block (100 mm square) of hard foamed urethane was placed, and glass (12 mm thick) was placed on the block. ) Was set, the antenna angle was set at a specified incident angle, and measurement was performed by a time domain measurement method. FIG. 5 shows the measurement results. At the same time, the measurement results of a conventional general-purpose PC type radio wave absorption panel are also shown. As shown in FIG. 5, the embodiment of the present invention shows good radio wave absorption performance in a wide frequency range.

In the above embodiment, the length of the ferrite plate (C
Direction) The dimensions are changed to 80 to 200 mm, but the purpose is to change the length of the ferrite plates to be laminated to reduce the gap at the plate joining surface in the magnetic field direction, and to specify the length. It does not do. Although the box-shaped metal case is made of aluminum plate, it is as lightweight as possible.
The material is not particularly limited as long as the material does not deform during the mounting operation during transportation.

In the above embodiment, the size of the box-shaped metal case is 600 mm in width × 1300 mm in length × 35 mm in height, but is not particularly limited. Since the required size is different depending on the size of the glass curtain, the size may be determined appropriately. Also, the height differs depending on the size of the ferrite plate, the required thickness of the calcium silicate plate, and the like.

The groove structure at the bottom of the box-shaped metal case is as follows.
The ferrite plates are arranged at a precise pitch and are formed to prevent inclination.The purpose is to maintain the parallelism of the electric field gap, and there is no particular limitation on the groove depth, structure, or manufacturing method. . Alternatively, a method may be used in which the ferrite plate is bonded and fixed in advance to a drawing plate made of aluminum or the like, and is attached to the bottom of the metal box at a specified pitch.

In the above-described embodiment, the calcium silicate plate 3 is mounted in the box-shaped metal case 1, but is not particularly limited as to the mounting method. This is for the purpose of aesthetic appearance and the purpose of preventing the ferrite plate from falling off. If high-frequency characteristics are important, it is not necessary to attach the ferrite plate.

In the present invention, the width of the ferrite plate is 5 m
The reason for defining the size as m to 9 mm is that 5
When the diameter is less than 9 mm, the deformation during sintering becomes large and it is not economical. The point specified as 9 mm or less is based on the propagation constant and experimental results. Space distance becomes longer, 600M
This is because the reflection loss characteristics (12 dB or more) near Hz cannot be satisfied. Also, the reason why the thickness of the ferrite plate is specified to be 15 to 22 mm is that, from various experimental results, matching cannot be achieved outside this range, and the reflection loss is 15 dB or more at a frequency of 90 to 220 MHz and 60 or more.
This is because the characteristics of 12 dB or more cannot be satisfied at 0 MHz. Also, the reason that the electric field gap ratio is specified to be 70 to 82% is that from the experimental results, it is assumed that 600 MHz is set outside this range.
This is because the reflection loss characteristics (12 dB or more) in the vicinity cannot be satisfied.

Further, in the radio wave absorption panel of the present invention,
A refractory board (for example, a calcium silicate plate) may be attached to the back of the box-shaped metal case. This fire board
The fireproof standard is defined depending on the installation position of the radio wave absorption panel. The fireproof panel is installed and may not be necessary. The box-shaped metal case and the fireproof board may be fixed with screws or 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 a radio wave obliquely incident on a wall having an incident angle of the radio wave of 30 ° to 60 °.

[0032]

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 partial sectional perspective view of a second 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 the second and third embodiments according to the present invention.

FIG. 5 is a characteristic diagram of a fourth embodiment according to the present invention and a conventional example.

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

FIG. 7 is a plan view showing an arrangement of a conventional ferrite plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Box-shaped metal case 2 Ferrite board 3 Calcium silicate board 4 Dielectric

Continued on the front page (72) Inventor Toshihiko Tanaka 70-2, Minamisakae-cho, Tottori-shi, Tottori Prefecture F-term in the Tottori Plant of Hitachi Metals, Ltd. (reference) 5J020 BD02 CA05 EA02 EA07 EA08 EA10 5J047 AA19 EF01

Claims (4)

[Claims] 1. A radio wave absorbing panel structure in which glass, air layer, radio wave absorber, and reflector are arranged in this order, the structure of the radio wave absorber has a width (A) of 5 to 9 mm and a thickness of (B).
A ferrite plate of 15 to 22 mm is used, the gap ratio in the electric field direction of the arriving radio wave is set to 70% to 84%, the ferrite plate is arranged continuously in the magnetic field direction, and the ferrite plate is formed of a box-shaped metal case. A radio wave absorbing panel structure that is fixed to a groove at the bottom. 2. The radio wave absorber according to claim 1, wherein the ferrite plate has a structure in which two or more types of ferrite plates having different material properties are laminated and integrated in a thickness (B) direction. Panel structure. 3. The radio wave absorbing panel structure according to claim 1, wherein a dielectric having a dielectric constant of 2.0 or less is disposed in the gap portion in the electric field direction. 4. The radio wave absorbing panel structure according to claim 1, wherein a decorative plate having a thickness of 10 mm or less is disposed on the upper surface of said ferrite.