JPH05335779A - Electric wave absorber - Google Patents

Abstract

PURPOSE:To provide an excellent electric wave absorbing characteristic regardless of electric wave polarization by overlapping two pieces of square panels provided with alloy thin strips laminated in the panel plane direction so as to permit the laminating directions to orthogonally intersect. CONSTITUTION:An electric wave absorber 1 is designed to provide an maximum absorbing characteristic when it is applied with an electric wave whose direction H of the magnetic field component is parallel to the laminating line and the direction E of the electric field component is permitted to orthogonally intersect with the laminating line. However, there is few case that the polarized wave of the electric wave is limited to be horizontal or vertical. Therefore, when the absorbers are arranged so as to permit the directions of the laminating lines to be uniform, an excellent electric wave absorbing characteristic is not attained. A square panel 4 is formed by laminating amorphous alloy thin strips which have high magnetic permeability in a direction that the panel plane extends. An electric wave absorber 5 is formed by laminating two pieces of the square panels 4 so as to permit the alloy thin strips to orthogonally intersect. Thus, the excellent electric wave absorbing characteristic is attained for any polarized wave.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention forms a radio wave absorbing layer by laminating metal magnetic ribbons in the direction of the panel surface and attaching a radio wave absorber configured as a rectangular panel to the outer wall surface of a building or the like. Regarding the radio wave absorber.

As a radio wave absorber in the band of 100 MHz to 1 GHz, a product obtained by impregnating urethane or the like with ferrite that utilizes magnetic loss, carbon having dielectric loss, or the like has been commercialized. However, these have a characteristic that they absorb electromagnetic wave energy by losing two components of electromagnetic waves, that is, only one of a magnetic field component and an electric field component (ferrite has only a magnetic field component, and carbon has only an electric field component). It is necessary to attach a reflector to the back side of the radio wave absorber. There is also a problem that the matching thickness (thickness that can be used as an absorber) is necessarily determined by the complex magnetic permeability μ ^* and the complex dielectric constant ε ^* .

Compared to ferrite, a metal magnetic material having a higher conductivity has a higher magnetic permeability at direct current, but has a drawback that the magnetic permeability becomes extremely low at higher frequencies. In order to maintain the magnetic susceptibility up to a high frequency range, powdering of a metal magnetic material, insulation and solidification, or lamination as a thin strip has been performed.

For the purpose of solving the above-mentioned problems of the electromagnetic wave absorber which has been conventionally used in a high frequency range of 100 MHz to 1 GHz, the applicant of the present invention has previously mentioned that a metal having an electric resistivity larger than 100 μΩ-cm. Thickness of magnetic material is 3 to 30μ
m, an initial magnetic permeability μ ₀ > 10000, and formed into an amorphous thin strip, laminated with an adhesive to form a panel, and stuck to an outer wall of a building or the like, so that the magnetic loss and the dielectric loss can be reduced in the above high frequency range. We have proposed an electromagnetic wave absorber that can be used together to form an electromagnetic wave absorption layer with excellent electromagnetic wave absorption characteristics.

Generally, the magnetic loss (μ ″) and dielectric loss (ε ″) of a substance in the high frequency range represent the basic characteristics of this substance. The former is complex permeability μ ^* = μ′−j
μ ″ (or loss angle tanδ = μ ″ / μ ′), and for the latter complex permittivity ε ″ = ε′−jε ″ (or loss angle tanδ =
It is known to be represented by ε ″ / ε ′. If the complex magnetic permeability and complex permittivity are known, the reflectance of this substance (when an incident electromagnetic wave is vertically incident on the substance is reflected by the substance surface) In the case) and the skin depth (thickness of the absorption layer until the incident electromagnetic wave is attenuated to 1 / e in the substance), the absorption characteristics of the substance can be known.

The electromagnetic wave absorber previously proposed by the applicant of the present invention has been obtained as a result of various studies to obtain the complex magnetic permeability μ ^* and the complex dielectric constant ε ^* required in the high frequency region. It is possible to achieve the object by laminating the high magnetic permeability amorphous alloy ribbons processed into a certain shape and size in the direction of the panel surface to form a panel-shaped electromagnetic wave absorber.

The above magnetic alloy improves the absorption characteristics by obtaining the required complex magnetic permeability (magnetic loss) μ ^* in the intended frequency range and also by generating the complex permittivity (dielectric loss) ε ^*. It is a thing.

The electromagnetic wave absorber 1 is, as shown in FIG.
A large number of alloy ribbons 2 are laminated in a direction parallel to the surface of the panel via an adhesive to form a panel. Its dimensions are
For example, a square having a thickness of 10 mm and a side length of 100 mm is formed. Therefore, innumerable parallel laminated lines 3 are formed on the surface of the panel by laminating the thin layers 2.

As shown in FIG. 2, the radio wave absorber 1 radiates radio waves such that the direction H of the magnetic field component of the radio wave is parallel to the laminated line 3 and the direction E of the electric field component is orthogonal to the laminated line 3. In this case, the absorption characteristics are designed to be maximized. Therefore, since TV radio waves and the like radiated from Tokyo Tower and the like are basically horizontally polarized waves, when this radio wave absorber is stuck to the outer wall of a building or the like to form a radio wave absorption layer, the case shown in FIG. As shown, if the electromagnetic wave absorbers 1 are lined up and stuck so that the laminated lines of all the electromagnetic wave absorbers are in the vertical direction that coincides with the magnetic field direction H, the absorption characteristics of all the electromagnetic wave absorbers 1 become maximum, and The purpose can be achieved.

However, in general, the polarization of radio waves is rarely limited to horizontal or vertical, and it can be said that there are both polarizations especially in the case of an anechoic chamber. In this case, good electromagnetic wave absorption characteristics cannot be obtained even if the electromagnetic wave absorbers are arranged so that the laminated lines are in one direction as shown in FIG.

[0011]

DISCLOSURE OF THE INVENTION The present invention is directed to a case where the above-mentioned radio wave absorber proposed by the present applicant is arranged so that the laminated lines are all in the same direction to form a radio wave absorption layer. In consideration of the deterioration of the electromagnetic wave absorption characteristics when the polarization of the radio waves is not limited to horizontal or vertical, good electromagnetic absorption characteristics can be obtained even when the polarization of the radio waves is not limited to horizontal or vertical. The task is to provide the structure of the body.

[0012]

A radio wave absorber according to the present invention for solving the above-mentioned problems is a rectangular panel 2 formed by laminating high-permeability amorphous alloy ribbons in a direction in which a panel surface extends. It is characterized in that it is formed by stacking and laminating the alloy ribbons so that the laminating directions of the alloy ribbons are orthogonal to each other.

[0013]

Since the radio wave absorber of the present invention is constructed as described above, if a radio wave having a magnetic field component parallel to the direction of the lamination line formed by the alloy ribbon lamination of the panel of the first layer hits, The maximum radio wave absorption rate is obtained. On the contrary, when the magnetic field component of the radio wave is orthogonal to the stacking direction of the first layer, the radio wave absorption rate is low, but the stacking line of the second layer is arranged to be perpendicular to the stacking line of the first layer. Therefore, the radio wave transmitted through the first layer is absorbed by the second layer with a high absorption rate. Even when the polarization direction of the radio wave is in the middle of these, it is possible to effectively absorb by a radio wave absorber by stacking two layers of radio wave absorption panels having laminated lines orthogonal to each other.

[0014]

Embodiments of the electromagnetic wave absorber of the present invention will be described in detail below with reference to the tables and the drawings.

As shown in FIG. 4, a thin strip having a thickness of 30 μm and a width of 5 mm of a high-permeability amorphous alloy of Co-Fe-Ni-Si-B system is laminated in the plane direction of the panel as shown in FIG. Then, create two panels 4 each having a thickness of 5 mm and a side length of 100 mm, and stacking them so that the innumerable parallel laminated lines formed on the surfaces of the panels are orthogonal to each other, and are bonded by an adhesive, A panel-shaped electromagnetic wave absorber 5 having a thickness of 10 mm was prepared. The volume ratio of the metal ribbon in this case is 75 vol%.

A radio wave absorber made of the same material as shown in FIG. 1 and having a thickness of 10 mm as a single layer structure and a radio wave absorber having the above two-layer structure are so constructed that the laminated lines on the surface are all in the same direction. Tightly attached to the wall surface of FIG. 5, FIG. 6, FIG. 7 and FIG.
As shown in FIG. 5, radio waves are applied to the single-layer structure absorber so that the magnetic field direction H is parallel to the direction of the lamination line. 6 is 1
Radio waves are applied to the layer structure absorber so that the electric field direction E is parallel to the direction of the lamination line. In FIG. 7, radio waves are applied to the two-layer structure absorber of the present invention such that the magnetic field direction H is parallel to the direction of the lamination line of the first layer. In FIG. 8, radio waves are applied to the two-layer structure absorber of the present invention such that the electric field direction E is parallel to the direction of the laminated line of the first layer. The frequency characteristics of the absorptance (db) of the absorber were measured for the above four cases, and the results are shown in Table 1.

[0017]

[Table 1]

As is clear from Table 1, the electromagnetic wave absorber of the present invention has almost no change in the electromagnetic wave absorption characteristics regardless of the polarization direction, and the absorber having a one-layer structure has a laminated line direction and a magnetic field direction. So that they coincide with each other, almost the same electromagnetic wave absorption characteristics as when a radio wave is applied can be obtained. Although not shown in Table 1 for the case where the polarization state is between these intermediate states, similar good absorption characteristics are obtained. Therefore, the electromagnetic wave absorber of the present invention can obtain good electromagnetic wave absorption characteristics even if the electromagnetic wave absorbers are stuck together without considering the direction of the laminated line of each panel.

[0019]

As described above, the electromagnetic wave absorber of the present invention is suitable for any polarization regardless of horizontal or vertical polarization, even if it is stuck on the wall of a building or the like regardless of the direction of the laminated line. Since the electromagnetic wave absorption characteristic can be obtained, the effect of improving the workability can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a radio wave absorber having a one-layer structure.

FIG. 2 is a perspective view illustrating the relationship between the direction of the laminated line of the radio wave absorber and the directions of the magnetic field and electric field of the incident radio wave.

FIG. 3 is an explanatory diagram showing the relationship between the direction of the laminated line of the radio wave absorber shown in FIG. 1 and the polarization direction of radio waves, in which good radio wave absorption characteristics are obtained.

FIG. 4 is an explanatory view illustrating a manufacturing process and a configuration of the radio wave absorber of the present invention.

FIG. 5: A radio wave absorber having a one-layer structure and a radio wave absorber having a two-layer structure of the present invention are stuck on a wall surface, respectively, and a radio wave is applied with the magnetic field direction and the electric field direction aligned with the direction of the laminated line on the absorber surface. It is a schematic diagram which shows a state.

FIG. 6 is a diagram showing a single-layered electromagnetic wave absorber and a double-layered electromagnetic wave absorber of the present invention, which are stuck on a wall surface, respectively, and a radio wave is applied with the magnetic field direction and the electric field direction aligned with the direction of the laminated line on the surface of the absorber. It is a schematic diagram which shows a state.

FIG. 7: A radio wave absorber having a one-layer structure and a radio wave absorber having a two-layer structure of the present invention are stuck on a wall surface, respectively, and a radio wave is applied with the magnetic field direction and the electric field direction aligned with the direction of the laminated line on the absorber surface. It is a schematic diagram which shows a state.

FIG. 8: A radio wave absorber having a one-layer structure and a radio wave absorber having a two-layer structure of the present invention are stuck on a wall surface, respectively, and a radio wave is applied by aligning a magnetic field direction and an electric field direction with a direction of a laminated line on the absorber surface. It is a schematic diagram which shows a state.

[Explanation of symbols]

 1 Conventional Single-Layered Radio Wave Absorber 2 High Permeability Amorphous Alloy Strip 3 Laminated Wire 5 Two-Layered Radio Wave Absorber H of the Present Invention H Magnetic Field Direction E Electric Field Direction

Claims (1)

[Claims] 1. Two rectangular panels formed by laminating high-permeability amorphous alloy ribbons in a direction in which a panel surface extends are laminated and laminated so that the lamination directions of the alloy ribbons are orthogonal to each other. An electromagnetic wave absorber characterized by being formed.