JP2920178B2 - Radio wave absorber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention has good radio wave absorption efficiency,
The present invention relates to a radio wave absorber that can significantly reduce the weight and a method of using the radio wave absorber.

[0002]

2. Description of the Related Art In recent years, in the social environment surrounding us, obstacles due to electromagnetic waves (hereinafter sometimes referred to as "radio waves") have occurred in various forms. For example, in ships and aircraft, the safety of operation is threatened by radar image artifacts due to the reflection of radio waves from structures. In the urban area, with the emergence of high-rise buildings,
Reflection of radio waves from high-rise buildings causes false images on the TV screen. Various radio wave absorbers are used according to the absorption frequency band of radio waves to solve these radio interferences.

Conventionally, as a radio wave absorber, a ferrite sintered body, ferrite, or a material obtained by mixing metal powder, metal fiber, carbon, or the like as a dielectric material with ferrite has been used. Since it is a main component and has the disadvantage of being heavy, it is a major problem in practical use. In particular, a radio wave absorber for preventing a false image of a television has a weight of 45 due to a long wavelength of radio waves to be absorbed.
Those that reach up to kg / m ² have been put to practical use. In order to reduce the weight of the radio wave absorber, the above-mentioned materials are also patterned, but in reality, sufficient performance has not been obtained in terms of radio wave absorption efficiency.

[0004]

The electromagnetic wave is a wave, and is composed of an electric field component (line of electric force) and a magnetic field component (line of magnetic force). The electromagnetic wave absorbing mechanism of the electromagnetic wave absorbing material is that of a dielectric material and a magnetic material. The purpose of the present invention is to convert electromagnetic wave energy into heat energy using dielectric relaxation and magnetic resonance phenomena. The present inventor has focused on the fact that the electric field component and the magnetic field component are orthogonal to each other in the electromagnetic wave and the transmission and reflection of the electromagnetic wave are related to the amplitude according to the wavelength. The present inventors have found that it is possible to achieve the present invention and arrived at the present invention.

That is, in the direction perpendicular to the amplitude plane of the magnetic field component, even if there is a slit between the strip-shaped dielectrics, if the width of the slit is smaller than the amplitude, almost no radio waves pass through the slit, and In the direction perpendicular to the amplitude plane of the component, even if there is a slit between the band-shaped magnetic materials, if the width of the slit is smaller than the width of the amplitude, almost no radio waves will pass through the slit, and conversely, each of the amplitude planes In the horizontal direction, the radio wave passes through the gap of the slit. For this reason, a band-shaped dielectric is arranged in the direction perpendicular to the amplitude plane for the magnetic field component so that the slit width is smaller than the amplitude width, and for the electric field component, It has been found that by arranging the band-shaped magnetic material in the vertical direction so that the slit width is smaller than the amplitude width, a light-weight radio wave absorber with good radio wave absorption efficiency can be obtained.

That is, according to the present invention, first, a plurality of dielectric rows in which a plurality of strip-shaped dielectrics are arranged at regular intervals in the longitudinal direction or a plurality of strip-shaped dielectrics are parallelly arranged at regular intervals. A plurality of strips of magnetic material or a plurality of strips of magnetic material arranged at regular intervals in the longitudinal direction with respect to the striped dielectric pattern layer (A) The magnetic layer (C) having a stripe pattern formed by arranging the layers in parallel at a predetermined interval is such that the stripes of the layer (A) and the layer (C) are orthogonal to each other. And a radio wave absorber having a structure in which the layer (C) is laminated on the radio wave reflector layer (E).

In the present invention, secondly, the total number of the dielectric pattern layer (A) and the magnetic pattern layer (C) is 3 to 15
Wherein the layer (A) and the layer (C) are laminated in any order.

Further, the present invention thirdly, the dielectric pattern layer (A) is formed on the support layer (B) as needed, and the magnetic pattern layer (C) is formed as necessary on the support layer (B). D) The radio wave absorber formed on the above.

Further, the present invention is directed to a dielectric pattern layer (A).
Wherein the distance between adjacent strip-shaped dielectrics or between adjacent dielectric rows (distance between center lines) in the layer (A) is １ ／ to ５ of the wavelength of the radio wave to be absorbed, And the width of the strip-shaped or strip-shaped dielectric is at least 1/10 and less than 1 of the distance between adjacent dielectrics or rows of dielectrics in the layer (A). Layer (C)
, The distance between adjacent strip-shaped magnetic substances or the row of magnetic substances (distance between center lines) in the layer (C) is 1/3 to 1/5 of the wavelength of the radio wave to be absorbed; The width of the strip-shaped or strip-shaped magnetic material is in a range of not less than 1/10 and less than 1 between the distances between adjacent magnetic materials or between the magnetic rows in the layer (C). The present invention provides the radio wave absorber.

Fifth, in the present invention, the sum of the thickness of the dielectric pattern layer (A) and the sum of the thickness of the magnetic pattern layer (C) are each 1/10 of the wavelength of the radio wave to be absorbed. ~ 1
/ 200 is provided.

A sixth aspect of the present invention is to provide a dielectric array in which a plurality of strip-shaped or strip-shaped dielectrics arranged in parallel at regular intervals are arranged at regular intervals in the longitudinal direction; A plurality of strip-shaped magnetic bodies or strip-shaped magnetic bodies arranged in parallel at regular intervals and a magnetic body row arranged in the longitudinal direction are arranged in a lattice shape orthogonal to each other, and if necessary. A multi-unit laminate formed by laminating a plurality of lattice-like laminate units formed on a support layer such that respective dielectrics and magnetic materials between the laminate units are orthogonal to each other, or the lattice-like laminate; An object of the present invention is to provide a radio wave absorber having a structure in which one body unit is laminated on a radio wave reflector layer (E).

Further, the present invention seventhly provides a method of manufacturing a radio wave apparatus as described above, wherein a stripe-shaped dielectric stripe or a strip-shaped or strip-shaped dielectric stripe direction is perpendicular to an amplitude plane of a magnetic field component of a radio wave to be absorbed. An object of the present invention is to provide a method of using the radio wave absorber, wherein the absorber is provided on a surface of a structure.

Eighth, the present invention provides a laminate obtained by removing the radio wave reflector layer (E) from the radio wave absorber, wherein the direction of the band-shaped dielectric stripes or the dielectric row stripes is equal to the radio wave to be absorbed. A method for using the radio wave absorber, wherein the radio wave absorber is formed on a radio wave reflection structure having a metal surface so as to be perpendicular to the amplitude plane of the magnetic field component.

In the electromagnetic wave absorber of the present invention, the dielectric is a dielectric material, for example, a perovskite-based oxide such as barium titanate or strontium titanate, or a ferroelectric material such as magnesium barium tetrafluoride (BaMgF ₄ ). Materials, for example, one or two or more kinds of powder or fibers of metal such as gold, platinum, silver, copper, nickel, aluminum, and iron or carbon or the like are kneaded and molded, or dispersed to form a coating composition. It can be prepared, applied on the support layer described below, and dried. In the case of metal powder or fiber, it is important that the concentration between the particles of the powder or fiber is kept at a minute interval by an organic insulating material or the like, and that it is in a dispersed state. No longer shows dielectric properties. Further, a sintered product obtained by sintering a molded product obtained by the above molding may be used.
The dielectric preferably contains a dielectric material in an amount of 10 to 100% by weight from the viewpoint of dielectric properties. In order to make the dielectric band-shaped or strip-shaped, molding or coating may be performed so as to be a band-shaped or strip-shaped at the time of molding or coating, or it may be performed by cutting a molded article or a coated article. .

Examples of the binder used for kneading and dispersing the above dielectric material include polyimide, polyphenylene sulfide, rosin, shellac, ester rubber, hypalone (chlorosulfonated polyethylene) rubber, chloride rubber, chloroprene rubber, polyolefin resin, and hydrocarbon. Resin, vinylidene chloride resin, polyamide resin, polyetherketone resin, vinyl chloride resin, polyester resin,
Resins such as alkyd resin, phenol resin, epoxy resin, acrylic resin, urethane resin, silicone resin, cellulose resin, and vinyl acetate resin are exemplified.

In the radio wave absorber of the present invention, the magnetic material is
Ferrite as a magnetic material can be obtained by kneading and molding or dispersing a ferrite in a binder to prepare a coating composition, applying the coating composition on a support layer, and drying. Further, the molded product obtained by the above-mentioned molding may be sintered into a sintered body of 100% ferrite. The magnetic material preferably contains 10 to 100% by weight of ferrite from the viewpoint of magnetism (magnetic permeability). In order to make the magnetic material into a band shape or a strip shape, molding or painting may be performed so that the magnetic material becomes a band shape or a strip shape at the time of molding, or a molded product,
It can also be performed by cutting the painted object.

As the ferrite, ferrite conventionally used in radio wave absorbers can be used, and typical examples are hematite (Fe ₂ O ₃ ) and magnetite (Fe ₃ O ₃ ).
₄ ), an iron oxide containing a dissimilar metal element generally represented by the composition MO.Fe ₂ O ₃ (M is Mn, Co, Ni, C
u, Zn, Ba, Mg, etc.). Although the particle size of the ferrite is not particularly limited, it is generally desirable that the particle size be 100 μm or less from the viewpoint of dispersibility and the like.

As the binder used for kneading and dispersing the ferrite, those listed above as the binder used for kneading and dispersing the dielectric material can be similarly used.

[0019]

In one embodiment of the radio wave absorber of the present invention,
The plurality of strip-shaped dielectrics are arranged in parallel at regular intervals to form a striped dielectric pattern layer (A), and the plurality of strip-shaped magnetic substances are arranged in parallel at regular intervals. The magnetic pattern layer (C) is formed on the radio wave reflector layer (E) so that the stripes of the dielectric pattern layer (A) and the stripes of the magnetic pattern layer (C) are orthogonal to each other. It has a laminated structure, for example, a laminated structure as shown in FIG. 1 described later. The dielectric pattern layer (A) may be formed on the following support layer (B) as required, and the magnetic pattern layer (C) may be formed on the following support layer (D) as necessary. It may be. The dielectric pattern layer (A) is formed by arranging a plurality of dielectric rows each having a plurality of strip-shaped dielectrics arranged at regular intervals in a longitudinal direction, and arranging the plurality of dielectric rows in parallel at regular intervals. It may be made into a shape. The magnetic pattern layer (C) is formed by arranging a plurality of magnetic material rows in which the plurality of strip-shaped magnetic materials are arranged at regular intervals in the longitudinal direction, and is arranged in parallel at regular intervals. It may be striped.

The support layer (B) is a layer which may be interposed as needed to support the dielectric pattern layer (A), and is not particularly limited.
A plastic sheet of about 500 μm is exemplified. The plastic sheet includes a plastic film. There are no particular restrictions on the type of plastic sheet, but polyamide, polyimide, polyester such as polyethylene terephthalate, polyvinyl chloride, polyvinylidene chloride, polyurethane, hypalon rubber, chloride rubber, chloroprene rubber, epoxy resin, acrylic resin, phenol resin, etc. Is mentioned. The plastic sheet includes a fiber-reinforced plastic sheet.

The support layer (D) is a layer which may be interposed as needed to support the magnetic pattern layer (C), and the same layer used as the support layer (B) is similarly used. be able to.

In the dielectric pattern layer (A), the distance between adjacent strip-shaped dielectrics or between adjacent dielectric rows (distance between center lines) is one of the wavelengths of the target radio wave to be absorbed.
The length is preferably / 3 to 1/5, more preferably 2/7 to 2/9 from the viewpoint of radio wave absorption efficiency. The width of the strip-shaped or strip-shaped dielectric is in the range of 1/10 or more and less than 1 of the distance between the adjacent strip-shaped dielectrics or the rows of dielectrics, and furthermore, 1/5 to 1/2. Is preferable in terms of radio wave absorption efficiency and weight reduction.

In the magnetic material pattern layer (C), the distance between adjacent strip-shaped magnetic materials or between the magnetic material rows (the distance between center lines) is 1/1 / the wavelength of the target radio wave to be absorbed.
The length is preferably 3 to 1/5, more preferably 2/7 to 2/9 from the viewpoint of radio wave absorption efficiency. Further, the width of the band-shaped or strip-shaped magnetic body is in a range of 1/10 or more and less than 1 of the distance between the adjacent band-shaped magnetic bodies or the row of magnetic bodies, and furthermore, 1/5 to 1/2. Is preferable in terms of radio wave absorption efficiency and weight reduction. The length of the strip-shaped magnetic material forming the magnetic pattern pattern layer (C) and the length of the strip-shaped dielectric material forming the strip-shaped dielectric pattern layer (A) are not particularly limited. From the point of view, usually those having a length in the range of 100 to 1000 mm are used.

In the present invention, the dielectric pattern layer (A) which may be formed on the support layer (B) if necessary, and the support may be formed on the support layer (D) if necessary. With respect to the magnetic pattern layer (C), the layer (A) and the layer (C) may be laminated on the radio wave reflector layer (E), which will be described later, such that each layer is a single layer. At least one of (A) and the layer (C) may be stacked so as to have a plurality of layers. The laminating order in the case of laminating a plurality of layers is not particularly limited, and may be arbitrary. However, the laminating may be performed such that the layer (A) and the layer (C) are alternately arranged, or the layer (A) may be continuous. After that, the layer (C) is laminated so as to be continuous, the layer (A) is on the space side, and the layer (C) is a radio wave reflector layer (E) described later.
It is advantageous from the viewpoint of radio wave absorption efficiency to dispose it to the side. When at least one of the layer (A) and the layer (C) has a plurality of layers, the total number of the layers (A) and (C) is preferably 3 to 15. Even when the layer (A) and the layer (C) are laminated one by one, they are arranged so that the layer (A) faces the space and the layer (C) faces the radio wave reflector layer (E) described later. This is advantageous from the viewpoint of radio wave absorption efficiency.

In the present invention, the total of the thickness of the dielectric pattern layer (A) [the thickness of the layer (A) when only one layer (A) is provided] and the thickness of the magnetic pattern layer (C) Sum of thicknesses [thickness of layer (C) when there is only one layer (C)]
Are 1/10 to 1/1 / the wavelength of the target radio wave to be absorbed.
It is preferably in the range of 500, more preferably 1/20 to 1/300 from the viewpoint of radio wave absorption efficiency and weight.

In another embodiment of the radio wave absorber of the present invention, a plurality of the strip-shaped or strip-shaped dielectrics arranged in parallel at a predetermined interval are arranged in the longitudinal direction at an interval. A dielectric row and a magnetic row in which a plurality of the strip-shaped magnetic bodies or strip-shaped magnetic bodies arranged in parallel at regular intervals are arranged at regular intervals in the longitudinal direction are orthogonal to each other in a lattice shape. A plurality of lattice-shaped laminate units arranged and formed on the support layer as necessary, each having a plurality of laminated dielectric units and magnetic bodies between the laminated unit so as to be orthogonal to each other It has a structure in which a unit laminate or one lattice-like laminate unit is laminated on the radio wave reflector layer (E).

As an example of the lattice-like laminate unit, a strip-like dielectric is arranged in a part of the gap between the band-like magnetic bodies to form a lattice (FIG. 2 described later). A strip-shaped magnetic body is arranged in a part of the gap between the strip-shaped dielectrics to form a grid, and a combination of a recessed strip-shaped dielectric and a recessed strip-shaped magnetic body is arranged. And a grid-like structure in which a strip-shaped dielectric and a strip-shaped magnetic material are arranged (see FIGS. 4 and 5).

In the lattice-shaped laminate unit, the dielectric pattern layer (A) and the magnetic pattern layer (C) are composed of a dielectric stripe of the layer (A) and a magnetic stripe of the layer (C). Are overlapped at right angles to each other, the overlapping portions of the stripes of the layer (A) and the stripes of the layer (C) are removed so as not to overlap, so that the overlapping portions are on the same plane without excess / shortage. A dielectric material and a magnetic material are arranged, and both are formed in an orthogonal lattice shape.
By using this lattice-shaped laminate unit, it is possible to make the thickness of the obtained radio wave absorber thinner than when using the dielectric pattern layer (A) and the magnetic pattern layer (C).

The distance (distance between center lines) between adjacent dielectrics in parallel with each other and the width of the dielectric in the lattice-like laminate unit are the same as those of the dielectric in the dielectric pattern layer (A). It is. Further, in the lattice-like laminate unit,
The distance between the magnetic bodies adjacent to each other in parallel, the width of the magnetic body is
This is the same as the case of the magnetic material in the magnetic material pattern layer (C).

In the lattice-like laminate unit, a plurality of units or one laminate unit may be laminated on the radio wave reflector layer (E) described later. In the case where a plurality of units are stacked, the respective dielectrics and magnetic materials between the respective lattice-shaped stacked units are stacked so as to be orthogonal to each other. In the radio wave absorber of the present invention, the sum of the thicknesses of the lattice laminate units (the thickness of one unit in the case of only one unit) is 1/10 to 1/500 of the wavelength of the target radio wave to be absorbed. Is 1/20 to 1/3
It is preferable to be in the range of 00 from the viewpoint of radio wave absorption efficiency and weight.

In any of the embodiments of the radio wave absorber according to the present invention, in the dielectric row in which the plurality of strip-shaped dielectrics are arranged at regular intervals in the longitudinal direction, the spacing in the longitudinal direction between the strip-shaped dielectrics. Is preferably 25% or less. Similarly, the ratio (porosity) of the longitudinal gap between the strip-shaped magnetic bodies in the magnetic body row is preferably 25% or less. Further, in any of the embodiments of the radio wave absorber of the present invention, the strip-shaped dielectric may be formed of one strip-shaped dielectric, or may be formed by, for example, arranging strip-shaped dielectrics without gaps in the longitudinal direction. Such as
A band-shaped dielectric may be formed by combining a plurality of dielectrics.

In one embodiment of the radio wave absorber of the present invention, the dielectric layer (A) which may be formed on the support layer (B) if necessary and the support layer (D) if necessary. The radio wave reflector layer (E) is laminated on the lowermost layer of one or more laminates of the magnetic material layer (C) which may be formed as follows. In the radio wave absorber according to another aspect of the present invention, a radio wave reflector layer (a lowermost layer of one or more units of a lattice-shaped laminate unit which may be formed on a support as necessary) is provided. E) are laminated. The radio wave reflector layer (E)
Means 100% or almost 100% of incoming radio waves
Any metal layer that can reflect (about 99% or more) can be used, and a metal sheet is generally used. The metal sheet also includes a metal foil. Examples of the type of the metal sheet include metal sheets such as tin, brass, copper, iron, nickel, stainless steel, and aluminum. The thickness of the metal sheet is not particularly limited, but is preferably about 5 to 500 μm from the viewpoint of strength and weight reduction.

In the radio wave absorber of the present invention, the respective layers may be bonded by an adhesive. In addition, the radio wave absorber of the present invention has an uppermost surface opposite to the radio wave reflector layer (E) of the radio wave absorber in order to improve the anticorrosion properties, weather resistance, cosmetic properties, and retention of material properties of the radio wave absorber. A clear or colored coating layer may be provided on the upper layer by painting or the like. Examples of the resin species forming the coating layer include an epoxy resin, a urethane resin, an acrylic resin, and a polyester resin.

In the method of using the radio wave absorber of the present invention, the radio wave absorber of the present invention is provided on the surface of a structure to be shielded from radio waves and to prevent reflection of the radio waves, on the surface of the amplitude of the magnetic field component of the radio wave to be absorbed. On the other hand, it is installed by sticking, for example, with an adhesive or the like such that the direction of the strip-shaped dielectric stripes or the stripes of the dielectric rows is vertical. For example, if the radio wave to be absorbed is a TV radio wave, the TV radio wave is a horizontally polarized wave (a radio wave whose amplitude plane of the electric field component is horizontal to the ground and whose amplitude plane of the magnetic field component is vertical to the ground) in an urban area. With respect to the magnetic field component, the band-shaped dielectric stripes or dielectric stripe stripes are arranged so as to be vertical to the amplitude plane, that is, horizontal to the ground. By arranging in this manner, with respect to the electric field component, the stripes of the band-shaped magnetic material or the stripes of the magnetic material row are arranged perpendicular to the amplitude plane, that is, perpendicular to the ground. By installing the radio wave absorber as described above, it is possible to effectively absorb the radio wave by exchanging the magnetic field component by the dielectric material and the electric field component by the magnetic material to heat energy.

In the method of using the radio wave absorber according to the present invention, when the structure to prevent the reflection of radio waves is a radio wave reflecting structure having a metal surface, the radio wave reflecting structure according to the present invention is used. Since it can perform the function of shielding radio waves in the same way as the radio wave reflector layer (E) of the radio wave absorber,
On this radio wave reflecting structure, a layered body obtained by removing the radio wave reflector layer (E) from the radio wave absorber and forming a layer (A) and a layer (B) and the lattice-shaped laminated body unit with respect to the radio wave to be absorbed. Radio waves can also be effectively absorbed by forming them in the above direction.

Further, an adhesive is applied in advance to the surface of the radio wave reflector layer (E) of the radio wave absorber of the present invention, and release paper is laminated thereon, whereby the release paper is peeled off at the construction site, and the structure is removed. Forming a radio wave absorber on a structure by attaching the layer (A) and the layer (B) and the lattice-shaped laminate unit to the body in the above-mentioned direction with respect to the radio wave to be absorbed. And can effectively absorb radio waves.

[0037]

The present invention will be described more specifically with reference to the following examples. Hereinafter, “parts” are based on weight.

Example 1 A magnetite-containing sheet having a thickness of 1 mm was formed by dispersing 200 parts of magnetite having an average particle size of about 10 μm in 100 parts of an epoxy resin and adding an amide-based curing agent using a heating extruder. Created. Separately, 200 parts of magnesium-barium tetrafluoride (BaMgF ₄ ) having an average particle size of about 8 μm was dispersed in 100 parts of an epoxy resin, and a dicyandiamide curing agent was added thereto.
An m-thick magnesium tetrafluoride / barium-containing sheet was prepared. Next, the magnetite-containing sheet was subjected to 120 ×
It is cut into a size of 300 × 1 mm to make a magnetic unit, which is made of polyethylene terephthalate (P) having a thickness of 100 μm.
ET) On a film, 3,000 pieces of 300 mm long magnetic material units are connected in the longitudinal direction without any gap.
m band-shaped magnetic material, and the band-shaped magnetic material was stuck so as to be arranged in parallel at a distance of 480 mm between the center lines to obtain a magnetic pattern layer. The proportion (porosity) of the portion having no magnetic substance on the PET film is 75%. Twelve PET films having the magnetic pattern layers were laminated such that the magnetic stripes of each magnetic pattern layer were in the same direction, to obtain a magnetic laminate having 12 magnetic pattern layers. Also, instead of the magnetite-containing sheet, magnesium tetrafluoride
Except for using a barium-containing sheet, cut, affix, and laminate in the same manner as above, and a dielectric pattern in which stripes of each dielectric (containing magnesium tetrafluoride and barium) are laminated in the same direction. A dielectric laminate having 12 layers was obtained.

Next, the obtained magnetic laminate was 1 m thick.
m on an aluminum plate, and further, on this magnetic laminate, place the obtained dielectric laminate on the magnetic laminate of the dielectric laminate so that the dielectric stripes are orthogonal to the magnetic stripes of the magnetic laminate. To form a radio wave absorber having a gap. In the radio wave absorber, the porosity is 0% in the same manner as described above except that the magnetite-containing sheet is used instead of the magnetic pattern layer and the magnesium tetrafluoride / barium-containing sheet is used instead of the dielectric pattern layer. Was obtained.
When the radio wave absorber having the air gap is placed so that the stripe of the band-shaped dielectric is perpendicular to the amplitude plane of the magnetic field component of the target radio wave to be absorbed, the peak of the radio wave absorption is 156M.
Hz and the relative band at -20 dB was 360 MHz. This absorption characteristic was almost equal to that of the radio wave absorber having the porosity of 0%. The weight of the radio wave absorber having the voids was 12 kg / m ^2, which was about 1/3 of the weight of the radio wave absorber having the porosity of 0%, 35 kg / m ² .

EXAMPLE 2 Ten ferrite sintered bodies (120.times.24.times.9 mm) were connected to a steel wall surface of a structural body, and ten sintered bodies (magnetic bodies) having a length of 120 mm were joined together in the longitudinal direction without gaps. 1200mm
The magnetic strips are arranged in parallel at an interval of 120 mm between their center lines, and the magnetic stripes (length direction) with respect to the amplitude plane of the electric field component of the target radio wave to be absorbed. Were mounted so that they were orthogonal. This wall (1200
The ratio (porosity) of the portion where no magnetic material exists on the (× 1200 mm area) is 80%. Further, a sintered body of strontium titanate (96 × 24 × 9 mm) forms a lattice perpendicular to the stripes of the magnetic body as shown in FIG. The sintered body (dielectric) having a length of 96 mm has a center line distance 12 in the width direction.
They were mounted so as to be arranged in parallel at an interval of 0 mm. Wall (12
The ratio (porosity) of the portion having neither the magnetic material nor the dielectric material on the area (area of 00 × 1200 mm) is 64%. As for the radio wave absorption characteristics of the obtained radio wave absorption structure, the absorption peak was 620 MHz, and the relative band at -20 dB was 450 MHz. This absorption characteristic is based on the steel wall (1
It was almost equivalent to a radio-wave absorbing structure having a porosity of 0% in which a band-shaped ferrite sintered body (120 × 24 × 9 mm) was adhered to an area of 200 × 1200 mm) without gaps. The weight of the radio wave absorbing structure having a porosity of 64% is 19.8 kg / m.
² , and the weight of the radio wave absorbing structure having the porosity of 0% is 4
It was 1/2 or less for 5 kg / m ² .

Example 3 300 parts of ferrite having an average particle size of about 10 μm was dispersed in 100 parts of neoprene rubber, and this was molded by a heating type extruder to prepare a 2.5 mm thick magnetic sheet. Separately, the average particle size is about 10 μm in 100 parts of neoprene rubber.
Of barium titanate and 5 parts of natural carbon were mixed and dispersed, and the mixture was molded by a heating-type extruder to prepare a dielectric sheet having a thickness of 2.5 mm. Each of these sheets was cut into a size of 150 × 450 mm to prepare a strip-shaped magnetic body and a strip-shaped dielectric.

On a polyimide sheet having a thickness of 100 μm,
The above-mentioned strip-shaped magnetic bodies are arranged vertically on a straight line at an interval of 29 mm, and the strip-shaped magnetic bodies are successively arranged side by side so that the distance between the center lines of adjacent strip-shaped magnetic bodies becomes 469 mm. Thus, a magnetic material pattern layer (C) was formed (see FIG. 6 described later). The porosity was about 6% in the longitudinal direction (the direction of the stripes) of the strip-shaped magnetic material, and was about 68% in the lateral direction. In the formation of the magnetic pattern layer, a dielectric pattern layer (A) was formed on a polyimide sheet having a thickness of 100 μm in the same manner except that a strip-shaped dielectric was used instead of the strip-shaped magnetic substance. did. Next, the dielectric pattern layer (A) having a polyimide sheet and the magnetic pattern layer (C) having a polyimide sheet are alternately formed by five sheets each, and the direction of the stripe of the dielectric pattern layer (A) and the magnetic material The stripes of the pattern layer (C) are overlapped so that the directions of the stripes are orthogonal to each other, and the lowermost layer is bonded so that the lowermost layer becomes a polyimide sheet having the magnetic material pattern layer (C). Thickness 50μ
A radio wave absorber having a gap adhered to an aluminum plate having a thickness of m was prepared.

In the above-described radio wave absorber having voids, the dielectric sheet having no voids is used in place of the dielectric pattern layer (A), and the magnetic sheet having no voids is replaced in place of the magnetic pattern layer (C). A radio wave absorber having no air gap was prepared in the same manner except that it was used. When the radio wave absorber having the air gap is installed such that strip-shaped dielectric stripes are perpendicular to the amplitude plane of the magnetic field component of the target radio wave to be absorbed,
The peak of radio wave absorption was 156 MHz, and the fractional band at -20 dB was 450 MHz. This absorption characteristic was almost equivalent to that of the radio wave absorber having no void. Further, the weight of the radio wave absorber having the gap was approximately 2/5 of the weight of the radio wave absorber having no gap.

[0044]

According to the radio wave absorber of the present invention, an electric field component of a radio wave to be absorbed is received by a magnetic substance, and a magnetic field component is received by a dielectric substance to exchange energy. Focusing on the fact that the radio wave to be absorbed is a wave in which the electric field component and the magnetic field component are orthogonal to each other, the magnetic material and the dielectric material are arranged in a striped space, and the conventional The radio wave absorber having the same absorption performance as the radio wave absorber having no air gap and having a weight of 1/2 or less can be obtained. The radio wave absorber of the present invention is
It has effects such as cost reduction, ease of construction, and reduction of the foundation of a building, and is particularly suitable for a radio wave absorber for preventing television false images.

[Brief description of the drawings]

FIG. 1 is a plan view (a) and a cross-sectional view (b) of a radio wave absorber in which a dielectric pattern layer (A) and a magnetic pattern layer (C) are laminated on a radio wave reflector layer (E).

FIG. 2 is a plan view (a) and a cross-sectional view (b) of a lattice laminate unit in which a strip-shaped dielectric is arranged in a part of a gap between strip-shaped magnetic bodies to form a lattice.

FIGS. 3A and 3B are a plan view (a) and a cross-sectional view (b) of a lattice-shaped laminate unit formed by combining a concave band-shaped dielectric and a concave band-shaped magnetic material in a lattice.

FIG. 4 is a plan view of a lattice-shaped laminated body unit in which a strip-shaped dielectric material and a strip-shaped magnetic material are combined and arranged to form a lattice shape;
And a sectional view (b).

FIG. 5 is a plan view of a lattice-shaped laminated body unit in which a strip-shaped dielectric material and a strip-shaped magnetic material are combined and arranged to form a lattice shape;
And a sectional view (b).

FIG. 6 is a plan view showing an example of a method of arranging strip-shaped magnetic materials in a magnetic material pattern layer.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 strip dielectric 2 strip magnetic substance 3 strip dielectric 4 strip magnetic substance 5 radio wave reflector layer a distance between center lines of dielectric substance b distance between center lines of magnetic substance

Claims (8)

(57) [Claims] 1. A stripe formed by arranging a plurality of strip-shaped dielectrics at regular intervals in the longitudinal direction or a plurality of strip-shaped dielectrics at regular intervals in parallel. A plurality of magnetic material rows or a plurality of band-like magnetic materials in which a plurality of strip-shaped magnetic materials are arranged at regular intervals in the longitudinal direction with respect to the dielectric pattern layer (A) are arranged at regular intervals. The layer (A) of the magnetic material pattern layer (C) arranged in parallel is arranged such that the stripes of the layer (A) and the layer (C) are orthogonal to each other.
And a radio wave absorber having a structure in which the layer (C) is laminated on the radio wave reflector layer (E). 2. The total number of the dielectric pattern layer (A) and the magnetic pattern layer (C) is 3 to 15, and the layer (A) and the layer (C) are laminated in an arbitrary order. The radio wave absorber according to claim 1, wherein: 3. The dielectric pattern layer (A) is formed on the support layer (B) as required, and the magnetic pattern layer (C) is formed on the support layer (D) as necessary. Claim 1 or 2
The radio wave absorber described. 4. In the dielectric pattern layer (A), the layer (A)
The distance (distance between center lines) between adjacent strip-shaped dielectrics or dielectric rows in the antenna is 1/3 of the wavelength of the radio wave to be absorbed.
The width of the strip-shaped or strip-shaped dielectric is at least 1/10 of the distance between adjacent dielectrics or dielectric rows in the layer (A), and And in the magnetic pattern layer (C), the layer (C)
The distance (distance between center lines) between adjacent band-shaped magnetic bodies or between adjacent magnetic body rows in the antenna is 1/3 of the wavelength of the radio wave to be absorbed.
The width of the strip-shaped or strip-shaped magnetic material is 1/10 or more of the distance between adjacent magnetic materials or magnetic material rows in the layer (C) and is 1/5 or less. The radio wave absorber according to any one of claims 1 to 3, wherein the range is less than the range. 5. The total of the thickness of the dielectric pattern layer (A) and the total of the thickness of the magnetic pattern layer (C) are both in the range of 1/10 to 1/200 of the wavelength of the radio wave to be absorbed. The radio wave absorber according to any one of claims 1 to 4, wherein 6. A dielectric array in which a plurality of strip-shaped or strip-shaped dielectrics arranged in parallel at regular intervals are arranged in the longitudinal direction at regular intervals, and arranged in parallel at regular intervals. A plurality of strip-shaped magnetic bodies or a plurality of strip-shaped magnetic bodies are arranged at regular intervals in the longitudinal direction, and the magnetic body rows are arranged in a lattice at right angles to each other, and formed on the support layer as necessary. A plurality of lattice-like laminate units, each of which is formed by laminating a plurality of dielectrics and magnetic substances between the laminate units so as to be orthogonal to each other, or one lattice-like laminate unit is a radio wave. An electromagnetic wave absorber having a structure laminated on a reflector layer (E). 7. A band-like dielectric stripe or a band-like or strip-like dielectric stripe direction is perpendicular to an amplitude plane of a magnetic field component of a radio wave to be absorbed. A method for using the radio wave absorber, wherein the radio wave absorber according to the above is disposed on a surface of a structure. 8. A laminate obtained by removing the radio wave reflector layer (E) from the radio wave absorber according to any one of claims 1 to 6, wherein a band-shaped dielectric stripe or a dielectric row stripe is oriented in a direction. A method of using the radio wave absorber, wherein the radio wave absorber is formed on a radio wave reflecting structure having a metal surface so as to be perpendicular to an amplitude plane of a magnetic field component of a radio wave to be absorbed.