JPH0750497A - Radio wave absorption panel - Google Patents

Abstract

PURPOSE:To enable coping with even a complex surface structure and lightweighting by a cylindrical ferrite core into a part of a structure reinforce ment bar of a facing PC panel. CONSTITUTION:A cylindrical ferrite core 2 25mm long having 25mm outer diameter, and 6.1mm inner diameter is inserted into a reinforcement bar 1 6mm in diameter. This reinforcement bar 1 is welded in a 75mm mesh form and bundled to form a double-layered structure reinforcement, which is driven into a lightweight concrete 3, thereby constituting a radiowave-absorbing panel. This makes the panel lightweighted by 1/3 of the prior art. Further, arc forms and rugged forms can be manufactured by a simple process with no facing materials, and it is unnecessary to consider falling of PC panels with integrated different kinds of materials by differences in coefficient of thermal expansion.

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 panel which is attached to the outer wall of a high-rise building and 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, and radio wave pollution such as ghosts on television screens has become a problem. As a countermeasure for this, there is a method of embedding a radio wave absorber in the outer wall of a high-rise building, and various radio wave absorption panels in which these ferrite plates are embedded have been proposed. FIG. 6 shows a cross-sectional view of an example of a conventional radio wave absorption PC panel, and FIG. 7 shows a structural view thereof. In this conventional example, the reinforcing bar 21 serving as a radio wave reflection plate is made of concrete 2
2, a ferrite plate 23 is attached to its surface continuously in the vertical direction with a gap in the horizontal direction, and an exterior material 24 such as granite is provided on the front surface thereof.

[0003]

The outer surface of a high-rise building sometimes has a complicated structure such as a concave shape, a convex shape, or an arc shape in terms of structure and design. In such a case, it has been extremely difficult to form a radio wave absorption panel by arranging ferrite plates in a complicated structure such as a concave shape, a convex shape, or an arc shape by the conventional structure. Further, the radio wave absorption panel having the conventional structure has a problem that the weight is heavy. In view of the above problems, the present invention provides a structure of a radio wave absorption panel that can cope with even a complicated surface structure and can reduce the weight.

[0004]

The present invention is a radio wave absorption panel in which a tubular ferrite core is inserted in a part of the structural strength line of an exterior PC panel. Further, in the present invention, the pitch of the mesh of the structural strength muscle is 750 mm or less, and one or more of the tubular ferrite cores are inserted for each mesh, and the outer diameter of the structural strength muscle is And the inner diameter of the tubular ferrite core is 0.2 mm or less, and a thermal expansion relaxation material is inserted into the gap.

[0005]

The present invention can be simply constructed by inserting a cylindrical ferrite core into the structural strength muscle. Further, by bending the structural strength line, it is possible to construct a radio wave absorption panel having a complicated structure such as an uneven shape and an arc shape.

[0006]

1 is a plan view showing the arrangement of ferrite cores according to an embodiment of the present invention, and FIG. 2 is a sectional view thereof. In this embodiment, a reinforcing bar 1 having a diameter of 6 mm has an outer diameter of 25 mm and a length of 2
A cylindrical ferrite core 2 having a diameter of 5 mm and an inner diameter of 6.1 mm is inserted, and the reinforcing bar 1 is welded into a mesh of 75 mm to be bundled to form a two-layer structural strength streak and a lightweight concrete 3 is cast. , Composed a radio wave absorption panel. In this example, the cylindrical ferrite core 2 was attached to one layer on the radio wave incident side of the two-layer structural strength muscle. The dimension a in FIG. 2 is 20.
The mm and b dimensions were 80 mm, the c dimension was 38 mm, and the d dimension was 150 mm. The size of the produced radio wave absorption PC panel was 3.2 m × 4.0 m × 0.15 m. According to this embodiment, the weight of the panel is equal to that of the conventional example.
It became / 3. Also, the arc shape and the uneven shape can be manufactured by a simple method. Furthermore, in the conventional structure, stone materials, tiles, etc. are used as the exterior material, and the ferrite plate is bonded to the back surface of them, which is a complicated construction method. However, in the present embodiment, the exterior material may be omitted, and it is not necessary to consider dropping out due to difference in thermal expansion of the PC panel integrated with different materials.

FIG. 3 shows the frequency characteristics of the radio wave absorption characteristics of the radio wave absorption panel of this embodiment. In FIG. 3, in the conventional example, the return loss is 15 dB or more at 100 MHz, 20
It is 12 dB or more at 0 MHz, and the radio wave absorption rate is 1
It is 97% at 00 MHz and 94% at 200 MHz. On the other hand, in the embodiment, the radio wave absorption rate is 100 MHz.
Although it is slightly inferior to about 94% for z and about 92% for 200 MHz, it is at a practical level particularly when the panel structure is not flat and the shapes such as irregularities and curved surfaces are taken into consideration. Also, the radio wave absorption rate can be adjusted by adjusting the outer diameter and length of the cylindrical ferrite core and the magnetic characteristics of the ferrite.
Further, it is a cylindrical ferrite core having an outer diameter of 30 mm and a length of 25 mm, and inner diameters of 6.1 mm, 6.2 mm and 6.4.
FIG. 4 shows the frequency characteristic of the return loss in mm. The outer diameter of the structural strength muscle is 6 mm. This Figure 4
From the above, it can be seen that if the difference between the outer diameter of the structural strength line and the inner diameter of the cylindrical ferrite core is larger than 0.4 mm, the attenuation amount cannot be obtained.

A sectional view of another embodiment according to the present invention is shown in FIG. This example is a cross-sectional view of a plane parallel to the horizontal plane of the panel, in which the center of the panel is curved. Two
The structural strength muscles 4 of the layer are embedded, and the outer strength of the radio wave incident side strength strength muscles 4 is 25 mm, the length is 40 mm, and the inner diameter is 6.1.
A cylindrical ferrite core 5 of mm is inserted. The structural strength line 4 is curved in accordance with the shape of the outer surface of the panel. Therefore, in this embodiment, even if the outer surface of the panel is uneven or arcuate, it can be easily configured. Also, in the conventional structure, there is a matching thickness for each incident angle of radio waves, and the thickness of the ferrite plate was changed to design the radio wave absorption panel. If the is uneven or arcuate, the incident angle is partially different and the electromagnetic wave absorption characteristics deteriorate. However, in the embodiment of the present invention, similar electromagnetic wave absorption characteristics could be obtained even if the incident angle was different. In the above embodiment, the cylindrical ferrite core as shown in FIG. 8A was used, but the outer shape of the ferrite core may not be circular, for example, as shown in FIG.
A square or hexagon as shown in (c) may be used. Further, the shape and the number of inserted ferrite cores are appropriately determined according to the intended electromagnetic wave absorption characteristics.

[0009]

According to the present invention, it is possible to obtain a radio wave absorbing panel which can be constructed even with a complicated surface structure and which can be made light in weight. Further, even when the radio wave incident angle changes, the radio wave absorbing panel can be absorbed. It is possible to obtain a radio wave absorption panel whose characteristics do not change.

[Brief description of drawings]

FIG. 1 is a plan view showing an arrangement of an embodiment according to the present invention.

FIG. 2 is a sectional view of an embodiment according to the present invention.

FIG. 3 is a radio wave absorption characteristic diagram of an example according to the present invention.

FIG. 4 is a radio wave absorption characteristic diagram when the inner diameter of the ferrite core of the example according to the present invention is changed.

FIG. 5 is a sectional view of another embodiment according to the present invention.

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

FIG. 7 is a structural diagram of a conventional example.

FIG. 8 is an explanatory diagram of a cylindrical ferrite core according to the present invention.

[Explanation of symbols]

 1 Reinforcing bar 2 Cylindrical ferrite core 3 Lightweight concrete

Claims (3)

[Claims] 1. A radio wave absorption panel in which a tubular ferrite core is inserted in a part of structural strength lines of an exterior PC panel. 2. The structure according to claim 1, wherein the mesh of the structural strength lines has a pitch of 750 mm or less, and one or more tubular ferrite cores are inserted for each mesh. Radio wave absorption panel. 3. The structure according to claim 1, wherein the gap between the outer diameter of the structural strength line and the inner diameter of the tubular ferrite core is 0.2 mm or less, and a thermal expansion relaxation material is inserted in the gap. Electromagnetic wave absorption panel characterized by.