JPH0821813B2 - 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 radio wave absorption wall which is attached to the outer wall of a high-rise building on which television radio waves are incident and which prevents unnecessary reflected waves of television radio waves.

[0002]

2. Description of the Related Art Recently, unnecessary reflected radio waves from high-rise buildings have become an obstacle to television broadcasting, causing so-called radio wave pollution such as causing ghosts on television screens. As measures against this, various electromagnetic wave absorption walls in which a ferrite plate is embedded in the outer wall of a high-rise building have been proposed. A cross-sectional view of an example of a conventional radio wave absorption wall is shown in FIG. In this conventional example, a reinforcing bar 54 serving as a radio wave reflector is embedded in concrete 53,
A ferrite plate 52 is attached to the surface thereof, and an exterior material 51 such as granite is provided on the front surface thereof. The angle of the TV radio wave incident on the radio wave absorption wall is always 0 ° depending on the location condition of the high-rise building and the transmission position of the TV radio wave.
Not necessarily in the (vertical direction), and in most cases, the light is obliquely incident with a certain incident angle. In the conventional technology, the design is performed by changing the thickness of the ferrite plate for this oblique incidence. That is, it has been common to set the optimum design condition by reducing the thickness of the ferrite plate as the incident angle increases.

[0003]

The reflection loss characteristic of the conventional electromagnetic wave absorbing wall is 15 at 100 MHz in the case of vertical incidence.
Although a high reflection loss of dB or more is obtained, the incident angle is 6
When it is as large as 0 °, there is a problem that even if the thickness of the ferrite plate is designed to be small, it is as small as 12 to 13 dB at 100 MHz, and sufficient reflection characteristics cannot be obtained. When the thickness of the outer layer material is as thin as 10 mm, the incident angle is 30 ° and 10
There is a problem that the reflection loss at 0 MHz is as small as 12 to 13 dB and further becomes 8 to 10 dB at an incident angle of 60 °. In view of the above problems, the present invention provides all angles of incidence of television radio waves of 0 to 90 ° (90 °).
It is an object of the present invention to provide a radio wave absorbing wall whose reflection loss characteristic of the radio wave absorbing wall is 15 dB or more at 100 MHz.

[0004]

[Means for Solving the Problems] As a result of earnest research in view of the above object, an outer layer material layer such as granite, a dielectric plate layer, a ferrite plate layer, and a concrete layer in which reflective reinforcing bars are embedded are formed in order from the arrival direction of radio waves. The structure, or in order from the direction of arrival of radio waves, is a structure consisting of a glass layer, a dielectric plate layer via an air layer, a ferrite plate layer, and a concrete layer in which reflective reinforcing bars are embedded, and the thickness of the dielectric plate is , 0 to 50 mm (0
The relative permittivity is set to 8 to 150 (1) at 100 MHz for all incident angles of TV radio waves.
The inventors have found that a high reflection loss of 5 dB or more can be obtained, and have conceived the present invention.

[0005]

EXAMPLE 1 The present invention will be described in detail below with reference to the accompanying drawings. FIG.
FIG. 3 is a cross-sectional view of a radio wave absorption wall according to the present invention. Thickness 1
0 mm, relative permittivity 30, length 500 mm, width 100 mm, dielectric plate 5 mm thick, height 100 mm, width 100 m
A ferrite plate having m and μi = 1,000 is temporarily fixed with an adhesive as shown in FIG. 2, and the dielectric plate with the ferrite plate is arranged to have a length of 4 m and a width of 3.5 m.
mm granite was bonded to the back surface of the granite continuously in the magnetic field direction of the radio wave and discontinuously in the electric field direction with a gap of 50 mm. A reflection reinforcing bar was arranged at a position of 20 mm from the back surface of the ferrite plate, and concrete was cast to form an electromagnetic wave absorbing wall having the structure shown in FIG. This radio wave absorption wall was evaluated by the free space standing wave method at an incident angle of 60 °. The results are shown in Example 11 in Table 1. In addition, the characteristics of the radio wave absorption wall having the above structure and having no dielectric plate are shown in Conventional Example 11. Further, in the above structure, the characteristics when the thickness and the relative permittivity of the dielectric plate are changed are shown in Table 1.

[0006]

[Table 1]

As is clear from Table 1, the electromagnetic wave absorption wall of the present invention has a frequency of 15 MHz at 100 MHz even when the incident angle is 60 °.
A high reflection loss of dB or more was obtained. Here, the reason for limiting the range of the thickness and the relative permittivity of the dielectric plate is that when the thickness is 50 mm or more (excluding 50 mm), the weight of the electromagnetic wave absorbing wall becomes too heavy, and when the relative permittivity is less than 8. As is clear from Comparative Example 11 in Table 1, the effect on the reflection loss is small, and when it is 150 or more (150 is not included), it is 10
The reflection loss at 0MHz is 15dB or more, but 2
This is because the reflection loss at 00 MHz is as small as 10 dB or less. Further, the thickness of the granite is preferably about 25 to 35 mm in view of strength and weight, and the distance from the back surface of the ferrite plate to the reflection reinforcing bar is preferably about 10 to 30 mm. Furthermore, the gap in the electric field direction of the ferrite plate is 3
About 0 to 80 mm is desirable, and the ratio of the total gap dimension to the electric field direction dimension of the radio wave absorption wall is 25 to 45%.
The degree is desirable. The dielectric plate is obtained by mixing conductive particles, fibers, etc. into rubber, resin, concrete, etc., and by changing the mixing ratio of the conductive particles, fibers, etc., a dielectric plate with a different dielectric constant can be obtained. Plates are easily obtained.

Example 2 The structure of Example 1 has a thickness of 15 instead of granite.
An electromagnetic wave absorbing wall having a mm porcelain tile as an exterior material was created. The thickness of the ferrite plate used for this electromagnetic wave absorption wall is 7
mm. This radio wave absorption wall was evaluated by the free space standing wave method at an incident angle of 40 °. Table 2 shows the above structure with 100 MHz when the thickness and the relative permittivity of the dielectric plate are changed.
Is the reflection loss at. As is clear from Table 2, in the radio wave absorption wall of the present invention, a high reflection loss of 15 dB or more was obtained at 100 MHz even when the thickness of the exterior material was as small as 15 mm and the incident angle was as large as 40 °.

[0009]

[Table 2]

Embodiment 3 FIG. 3 is a sectional view of a radio wave absorption wall according to the present invention. A dielectric plate having a thickness of 10 mm and a relative dielectric constant of 40 is arranged to have a length of 4 m and a width of 3.5 m, and a back surface of the dielectric plate has a thickness of 6 m.
As shown in FIG. 4, a ferrite plate with m, 100 mm in length, 100 mm in width, and μi = 1,000 was temporarily discontinuously bonded with an adhesive material in the magnetic field direction of the radio wave and with a gap of 50 mm in the electric field direction. I stopped it. 20 mm from the back of the ferrite plate
The reflective rebar is placed at the position of, and concrete is poured, and the thickness of the dielectric plate is 12 on the surface of the dielectric plate through a space of 50 mm.
mm plate glass was attached, and the electromagnetic wave absorption wall having the structure shown in FIG. 3 was created. This radio wave absorption wall was evaluated at an incident angle of 45 °. The results are shown in Example 31 in Table 3. Further, in the above structure, Table 3 shows the characteristics when the thickness and the relative permittivity of the dielectric plate are changed.

[0011]

[Table 3]

As is clear from Table 3, the electromagnetic wave absorbing wall of the present invention has a frequency of 15 MHz at 100 MHz even when the incident angle is 45 °.
A high reflection loss of dB or more was obtained. Here, the thickness of the plate glass is 5 to 20 mm due to problems of strength and weight.
It is desirable that the distance between the back surface of the plate glass and the front surface of the dielectric plate be approximately 20 to 150 mm. As described above, even in the radio wave absorption wall of various structures, by arranging the dielectric plate in the radio wave arrival direction of the ferrite plate, a high reflection loss can be obtained at 100 MHz with respect to the entire incident angle of the radio wave. .

[0013]

According to the conventional radio wave absorption wall, the reflection loss which becomes smaller than 15 dB at 100 MHz becomes smaller as the incident angle of the TV radio wave becomes larger. 15 dB for incident angle
The above-mentioned high reflection loss can be obtained, and the ghost trouble of the television can be eliminated.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a radio wave absorption wall according to the present invention.

FIG. 2 is a perspective view of a configuration example of a ferrite plate and a dielectric plate according to the present invention.

FIG. 3 is a cross-sectional view of a radio wave absorption wall according to the present invention.

FIG. 4 is a perspective view of a configuration example of a ferrite plate and a dielectric plate according to the present invention.

FIG. 5 is a cross-sectional view of a conventional radio wave absorption wall.

[Explanation of symbols]

 11, 51 Exterior materials such as granite 12, 33 Dielectric plate 13, 34, 52 Ferrite plate 14, 35, 53 Concrete 15, 36, 54 Reflective rebar 31 Glass 32 Space

Claims (2)

[Claims] 1. A structure comprising an exterior material layer such as granite, a dielectric plate layer, a ferrite plate layer, and a concrete layer in which reflective reinforcing bars are embedded in order from the direction of arrival of radio waves. , 0 to 50 mm (excluding 0) and a relative dielectric constant of 8 to 150. 2. A glass layer in order from the direction of arrival of radio waves,
A structure comprising a dielectric plate layer, a ferrite plate layer, and a concrete layer in which reflective reinforcing bars are embedded via an air layer, wherein the dielectric plate has a relative permittivity of 0 to 50 mm (not including 0). Is an electromagnetic wave absorbing wall.