KR102023397B1 - Bi-facial type radio wave absorbent - Google Patents

Abstract

According to an embodiment of the present invention, provided is a double-sided electromagnetic wave absorber, which forms a stealth structure. The double-sided electromagnetic wave absorber comprises: a first electromagnetic wave absorbing layer absorbing incident electromagnetic waves in a first frequency band; a second electromagnetic wave absorbing layer absorbing incident electromagnetic waves in a second frequency band; and a wave reflection layer formed between the first wave absorbing layer and the second wave absorbing layer to reflect the electromagnetic wave passing through the first electromagnetic wave absorbing layer and the electromagnetic wave passing through the second electromagnetic wave absorbing layer.

Description

Double-sided wave absorber {BI-FACIAL TYPE RADIO WAVE ABSORBENT}

The present invention relates to a double-sided wave absorber, and more particularly to a double-sided wave absorber is formed on both surfaces of the radio wave reflection layer, applied to the stealth structure.

As the battlefield environment becomes more advanced, stealth technology is gaining attention as it can perform its missions without being identified by enemy detection networks. Stealth technology in a comprehensive sense refers to technologies related to a series of methods for increasing survivability by minimizing electromagnetic signals, infrared signals, acoustic signals, and optical signals generated or exposed from an object. Weapon systems currently under development are equipped with increasingly sophisticated electronic equipment and sensors for a variety of missions, thereby reshaping the battlefield environment towards electronics and information warfare. Therefore, in the stealth technology, the technology of reducing the electromagnetic signal is considered the most important.

Currently, weapon systems are applied with stealth technology in the form of applying Radar Absorbing Material (RAM) or Radar Absorbing Structure (RAS) to the outer surface of the object according to the corresponding radar frequency. Although this method can cope with electromagnetic waves incident from an external radar, there are some weak points in the multiple reflection phenomenon of the cavity structure and the exposure of electromagnetic signals emitted from the electronic equipment in which the object is mounted.

1 is a cross-sectional view of a conventional radio wave absorber applied to a stealth structure. Referring to FIG. 1, a conventional radio wave absorber 10 applied to a stealth structure is composed of a radio wave absorbing layer 11 and a radio wave reflecting layer (or radio wave shielding layer) 12, and the radio wave absorbing layer 11 is formed on the outer surface of the stealth structure. Corresponding.

Generally, the electromagnetic wave absorbing layer 11 and the radio wave reflecting layer 12 are formed of a material having a different thermal expansion coefficient and structural strength and rigidity due to functional differences. Specifically, the radio wave reflecting layer 12 is formed of a material having a higher structural strength and rigidity than the radio wave absorbing layer 11, which causes problems such as warpage and warpage between layers in manufacturing a stealth structure having an irregular surface. There was.

Meanwhile, Korean Patent Publication No. 1944959 (2019.01.28.) (Hereinafter referred to as “priority document”) discloses a stealth structure to which a radio wave absorber composed of a front layer, a radio wave absorption layer, and a radio wave reflection layer is applied.

In the case of the prior document, there is a difference from the structure of the wave absorber 10 shown in FIG. 1 in that it further includes a front layer that transmits electromagnetic waves incident from the outside, but problems such as distortion occurring in the process of manufacturing the stealth structure are still present. Existed.

The present invention has been made to solve the above problems, an object of the present invention is to provide a double-sided wave absorber is formed on both surfaces of the radio wave reflection layer, applied to the stealth structure.

The double-sided wave absorber according to the embodiment of the present invention forms a stealth structure, the first wave absorption layer absorbing incident electromagnetic waves of the first frequency band, the second wave absorption layer absorbing incident electromagnetic waves of the second frequency band, and The electronic device may include a radio wave reflection layer formed between the first radio wave absorption layer and the second radio wave absorption layer to reflect the electromagnetic wave passing through the first radio wave absorption layer and the electromagnetic wave passing through the second radio wave absorption layer.

In the present embodiment, the second wave absorption layer is disposed to face the inside of the stealth structure, and the second frequency band absorbed by the second wave absorption layer is the first frequency band absorbed by the first wave absorption layer. May be a lower band.

In the present embodiment, the radio wave reflection layer may be formed to a thickness thicker than the skin depth of at least the first frequency band and the second frequency band.

In the present embodiment, the radio wave reflection layer may be formed to have a different thickness according to the load region of the stealth structure.

In the present embodiment, the first radio wave absorption layer and the second radio wave absorption layer may be formed in different thicknesses.

In the present embodiment, at least one of the first wave absorption layer and the second wave absorption layer may not have a constant thickness.

In the present embodiment, the first wave absorption layer and the second wave absorption layer may include a low dielectric loss material layer having one surface in contact with the radio wave reflection layer and the high dielectric loss material layer having one surface in contact with the other surface of the low dielectric loss material layer. It may include.

In this embodiment, the low dielectric loss material layer may be formed of a foam core or glass fiber reinforced composite material (GFRP).

In the present embodiment, the low dielectric loss material layer included in the first radio wave absorption layer and the low dielectric loss material layer included in the second radio wave absorption layer may have at least one of a thickness and a material.

In the present embodiment, the high dielectric loss material layer may be provided as a sheet printed so that the conductive paste has a specific pattern.

In the present embodiment, the high dielectric loss material layer included in the first electromagnetic wave absorbing layer and the high dielectric loss material layer included in the second electromagnetic wave absorbing layer are selected from among the shape of the pattern, the size of the pattern, the components of the paste, and the amount of the paste. At least one may be different.

In the present exemplary embodiment, the adhesive layer may further include an adhesive layer between the first radio wave absorption layer, the radio wave reflection layer, and the second radio wave absorption layer and the radio wave reflection layer.

In the present embodiment, the radio wave reflection layer may be formed of an iron-aluminum alloy, a carbon fiber reinforced composite material (CFRP) or a glass fiber reinforced composite material (GFRP) coated with a metallic element.

The double-sided electromagnetic wave absorber according to the embodiment of the present invention has an effect that the electromagnetic wave absorbing layer is formed on both surfaces of the radio wave reflecting layer so as to correspond to the electromagnetic wave generated from the inside as well as the electromagnetic wave incident from the outside of the stealth structure.

In addition, by having a quasi-symmetrical structure in which a radio wave absorption layer is formed on both surfaces of the radio wave reflection layer formed of a high strength and high rigidity material, it is possible to suppress the occurrence of interlayer distortion when manufacturing a three-dimensional stealth structure having a curved surface. By minimizing the electromagnetic scattering element can be controlled.

1 is a cross-sectional view of a conventional radio wave absorber applied to a stealth structure.
2 is a cross-sectional view of a double-sided wave absorber according to an embodiment of the present invention.
3 and 4 are cross-sectional views of a double-sided wave absorber according to a modified embodiment of the present invention.
5 is a view showing a detailed layered structure of a double-sided wave absorber according to an embodiment of the present invention.
6 is a graph showing the results of analyzing the radio wave absorption performance of the double-sided wave absorber according to FIG.
7 (a) to 7 (c) are views showing various embodiments of a stealth structure for RCS analysis.
FIG. 8 is a graph showing an RCS analysis result according to an incident angle of electromagnetic waves in each of FIGS. 7A to 7C.

The present invention relates to a double-sided wave absorber applied to the stealth structure, it will be described in more detail with respect to various embodiments of the present invention.

In the present specification, the stealth structure may refer to any structure used for military purposes, including aircraft (fighters), vehicles, ships, and the like.

2 is a cross-sectional view of a double-sided wave absorber according to an embodiment of the present invention, Figures 3 and 4 are cross-sectional views of a double-sided wave absorber according to a modified embodiment of the present invention.

Referring to FIG. 2, the double-sided wave absorber 100 according to an embodiment of the present invention includes a first wave absorbing layer 110, a second wave absorbing layer 120, and a first wave absorbing layer 110 and a second wave. It may include a radio wave reflection layer 130 formed between the absorbing layer (120).

The first wave absorbing layer 110 and the second wave absorbing layer 120 may form both surfaces of the stealth structure. Specifically, any one of the first wave absorption layer 110 and the second wave absorption layer 120 may correspond to the outer surface of the stealth structure, and the other may correspond to the inner surface. As such, the stealth structure formed of the double-sided wave absorber 100 may correspond to electromagnetic waves generated from the inside as well as electromagnetic waves incident from the outside.

The first wave absorption layer 110 and the second wave absorption layer 120 may absorb electromagnetic waves of different frequency bands. For example, the first electromagnetic wave absorbing layer 110 may absorb incident electromagnetic waves of the first frequency band, and the second electromagnetic wave absorbing layer 120 may absorb incident electromagnetic waves of the second frequency band. The first frequency band and the second frequency band may be arbitrarily set according to the operating environment or mission of the stealth structure.

In one embodiment, the first frequency band absorbed by the first wave absorbing layer 110 and the second frequency band absorbed by the second wave absorbing layer 120 may be determined according to the arrangement relationship of the wave absorbing layers 110 and 120. have.

Specifically, the frequency band may be determined by whether the first radio wave absorption layer 110 and the second radio wave absorption layer 120 form either of both surfaces of the stealth structure, and preferably the operating environment of the stealth structure. Considering this, the wave absorbing layer disposed to face the inside of the stealth structure may absorb electromagnetic waves of a relatively low frequency band. At this time, for example, the second wave absorption layer 120 absorbs electromagnetic waves corresponding to MHz bands (low frequency bands) such as UHF and VHF, and the first wave absorption layer 110 has a GHz band (such as X-band). Absorbs electromagnetic waves corresponding to a high frequency band).

 The above-described frequency bands of the electromagnetic waves absorbed by the first and second electromagnetic wave absorbing layers 110 and 120 are just examples, and the frequency bands absorbed by the first electromagnetic wave absorbing layer 110 and the second electromagnetic wave absorbing layer 120. The range may be determined in consideration of the mission of the stealth structure and the like. That is, even if the first wave absorption layer 110 is disposed outside the stealth structure, it may be designed to absorb a lower frequency band than the second wave absorption layer 120.

The first and second radio wave absorption layers 110 and 120 may be formed of a material having structurally low strength and rigidity in order to realize dielectric properties. In addition, the first and second radio wave absorption layers 110 and 120 may be designed in various forms (eg, Salisbury, Dallenbach, CA-absorber type, etc.) of a single layer or a multilayer structure according to the frequency band of the electromagnetic wave to be absorbed. It may be formed in different thicknesses.

On the other hand, since the actual electromagnetic wave may be incident on the stealth structure at multiple angles, at least one of the first electromagnetic wave absorbing layer 110 and the second electromagnetic wave absorbing layer 120 may be a layer whose thickness is not constant. In this case, the non-uniform thickness layer may be a layer corresponding to the outer surface of the stealth structure.

The radio wave reflection layer 130 may be configured to shield the electromagnetic wave by reflecting the electromagnetic wave so that the electromagnetic wave incident to the stealth structure is not transmitted to the opposite side of the incident direction. That is, in the present invention, the radio wave reflection layer 130 may reflect the electromagnetic wave passing through the first wave absorption layer 110 or the second wave absorption layer 120 back to the wave absorption layers 110 and 120 through which the electromagnetic wave passes. .

The radio wave reflection layer 130 may be formed to have a thickness thicker than the skin depth of at least the first frequency band and the second frequency band to reflect the electromagnetic wave. The skin depth is different depending on the frequency band, and it is possible to determine whether the incident electromagnetic wave is transmitted (thickness below the skin depth) or reflected (thickness above the skin depth). Accordingly, the radio wave reflection layer 130 may be formed to have a thickness thicker than the skin depth of the first and second frequency bands, which are at least frequency bands of the incident electromagnetic waves, in order to reflect the incident electromagnetic waves.

The radio wave reflection layer 130 may be configured to support the load of the stealth structure, and may be formed of a material having excellent strength and rigidity structurally. For example, the radio wave reflection layer 130 is formed of an iron-aluminum alloy, carbon fiber reinforced plastics (CFRP), or glass fiber reinforced plastics (GFRP) coated with metallic elements. Can be. The metal-based element may be, for example, iron (Fe), nickel (Ni), cobalt (Co), and the like, and may be coated with a predetermined thickness or more on a glass fiber reinforced composite (GFRP) surface. In addition to the material, the radio wave reflection layer 130 may be replaced with another high strength lightweight material capable of performing a function of reflecting or shielding electromagnetic waves.

The radio wave reflection layer 130 may be formed to have a different thickness according to the load region of the stealth structure. As shown in FIG. 3, the radio wave reflecting layer 130 applied to the high load region (eg, wing root, etc.) of the stealth structure is less than the radio wave reflecting layer 130 applied to the low load region (eg, wing tip pairing, inspection window, etc.). It can be formed thick. However, even in this case, the thickness of the radio wave reflecting layer 130 may be formed to be thicker than the skin depth of at least the first frequency band and the second frequency band as described above.

Meanwhile, when the radio wave reflection layer 130 is formed of a carbon fiber reinforced composite material, the thickness of the radio wave reflection layer 130 may be adjusted by gradually increasing or decreasing the number of chains according to the area where the radio wave reflection layer 130 is applied.

Referring to FIG. 4, the double-sided wave absorber 100 according to the present invention includes an adhesive layer between the first wave absorbing layer 110, the wave reflecting layer 130, and the second wave absorbing layer 120, and the wave reflecting layer 130. 140) may be further included.

When the adhesive layer 140 is separately formed between the electromagnetic wave absorbing layers 110 and 120 and the electromagnetic wave reflecting layer 130, the electromagnetic wave absorbing layers 110 and 120 are easily attached to the electromagnetic wave reflecting layer 130 or the electromagnetic wave absorbing layers 110 and 120 are provided. ) Can be removed from the radio wave reflecting layer 130 so that the radio wave absorbing layers 110 and 120 can be easily replaced, such as a change in the operating environment or mission of the stealth structure or damage to the radio wave absorbing layers 110 and 120. There are advantages to it.

On the other hand, the adhesive layer 140 may be provided in the form of an adhesive film containing an adhesive component, such as acrylic, silicone.

5 is a view showing a detailed layered structure of a double-sided wave absorber according to an embodiment of the present invention.

Referring to FIG. 5, the first wave absorption layer 110 and the second wave absorption layer 120 formed on both surfaces of the wave reflection layer 130 may have a high dielectric loss material layer 111 and 121 and a low dielectric loss material layer ( 112 and 122 (hereinafter, referred to as 'first high dielectric loss material layer 111', 'second high dielectric loss material layer 121', and 'first low dielectric loss material layer 112'). ',' Second low dielectric loss material layer 122 ').

One surface of the low dielectric loss material layers 112 and 122 is in contact with both surfaces of the radio wave reflection layer 130, and one surface of the high dielectric loss material layers 111 and 121 is not in contact with the radio wave reflection layer 130. It may be formed to contact the other surface of the material layer (112, 122). As described above, the high dielectric loss material layers 111 and 121 are formed outside the low dielectric loss material layers 112 and 122 to separate the low dielectric loss material layers 112 and 122 from external factors such as invasion and impact of the stealth structure. I can protect it.

The high dielectric loss material layers 111 and 121 are thin layers formed of high dielectric loss materials to form high impedance, and the low dielectric loss material layers 112 and 122 are made of low dielectric loss materials and have a relatively thick thickness. It is formed to form an inductance (inductance) by the thickness. Therefore, under the above structure, the high dielectric loss material layers 111 and 121 and the low dielectric loss material layers 112 and 122 may absorb electromagnetic waves by causing resonance with respect to incident electromagnetic waves.

In this embodiment, various combinations of materials, thicknesses, and the like of the high dielectric loss material layers 111 and 121 and the low dielectric loss material layers 112 and 122 can be implemented to implement radio wave absorption characteristics in any desired frequency range. have.

For example, the low dielectric loss material layers 112 and 122 are formed of a foam core or glass fiber reinforced composite material (GFRP), and the high dielectric loss material layers 111 and 121 are formed on the glass fiber reinforced composite material (GFRP). It can be configured by impregnating a predetermined amount or more of a magnetic material, a conductor, etc. by a method such as coating or printing.

Glass fiber reinforced composite material (GFRP) is a material that combines aromatic nylon fibers such as glass fibers, carbon fibers, kevlar, and thermosetting resins such as unsaturated polyester and epoxy resins, and the low dielectric loss material layers 112 and 122 are formed of the glass. When fabricated with GFRP, it can contribute to the stiffness reinforcement of stealth structures by acting as a high strength and high rigidity structure.

Meanwhile, the low dielectric loss material layers 112 and 122 may be manufactured in a honeycomb structure.

The thicknesses t₁ and t2 of the first and second low dielectric loss material layers 112 and 122 may be determined by frequency bands of incident electromagnetic waves absorbed by the first and second radio wave absorption layers 110 and 120. Since the first wave absorption layer 110 and the second wave absorption layer 120 absorb electromagnetic waves of different frequency bands, the first low dielectric loss material layer 112 and the second low dielectric loss material layer 122 are different from each other. It may be formed in a thickness. Meanwhile, the thicknesses t and t2 of the first and second low dielectric loss material layers 112 and 122 may be determined by the characteristics of the high dielectric loss material layers 111 and 121 to be described later.

Meanwhile, as another embodiment, the high dielectric loss material layers 111 and 121 may be provided as sheets printed so that the conductive paste has a specific pattern. For example, the high dielectric loss material layers 111 and 121 may be conductive. The sheet may be a sheet printed such that the paste has a periodic arbitrary pattern. As the conductive paste, conductive carbon nanotubes (CNT), carbon black (CB), nano silver, or the like may be used.

At this time, the high dielectric loss material layers 111 and 121 exhibit a capacitance effect according to the shape of the printed pattern, the size of the pattern, the paste component, and the amount of the paste, and thus can cope with various frequency bands. .

Therefore, since the first wave absorption layer 110 and the second wave absorption layer 120 absorb electromagnetic waves of different frequency bands, the first high dielectric loss material layer 111 and the second high dielectric loss material layer 121 have a pattern. At least one of the shape of the, the size of the pattern, the paste component and the paste amount can be formed to be different.

That is, in summary, the first radio wave absorption layer 110 and the second radio wave absorption layer 120 may have high dielectric loss material layers 111 and 121 having different dielectric properties and inner sides of the high dielectric loss material layers 111 and 121. The combination of the material and the thickness of the low dielectric loss material layers 112 and 122 formed in the material can realize radio wave absorption performance for a specific frequency band.

6 is a graph showing the results of analyzing the radio wave absorption performance of the double-sided wave absorber according to FIG.

In this simulation, high dielectric loss material layers 111 and 121 were applied with glass reinforced fiber composite material (GFRP) impregnated with carbon nanotubes (CNT), and the thickness was selected between 0.2 and 0.5 mm. On the other hand, the low dielectric loss material layers 112 and 122 were applied with a low density foam core, and the dielectric constant real term of the foam core was set to have a value near one.

The reflection loss of the y-axis in the graph shown in FIG. 6 refers to the correlation of electromagnetic energy reflected back from the incident electromagnetic energy, and -10dB is 90%, -20dB is 99% absorption performance. Means.

According to the graph of FIG. 6, under the above conditions, the first electromagnetic wave absorbing layer 110 and the second electromagnetic wave absorbing layer 120 correspond to 5 to 7 GHz frequency band (C-band) and 12 to 18 GHz frequency band (Ku-band), respectively. It can be seen that it exhibits a high absorption performance of -10 dB or more with respect to electromagnetic waves.

7 (a) to (c) are views showing various embodiments of a stealth structure for RCS analysis, and FIG. 8 is an RCS analysis according to an incident angle of electromagnetic waves in each of (a) to (c) of FIG. 7. A graph showing the results.

Specifically, Figure 7 (a) is a stealth structure formed only of the radio wave reflection layer, Figure 7 (b) is a stealth structure formed with the radio wave absorption layer on the outer surface of the radio wave reflection layer, Figure 7 (c) is an embodiment of the present invention Likewise, the stealth structure is shown in which a radio wave absorption layer is formed on both surfaces of the radio wave reflection layer.

The stealth structure according to FIG. 7 for the present simulation is a model of an air intake of an aircraft, and is a taper-shaped cylinder having a hollow formed therein, and as shown, the inlet side A is opened and the opposite side B is shown. Is a closed structure. In addition, it was modeled as a PEC (Perfect electromagnetic conductor) having a characteristic of total reflection of incident electromagnetic waves reflecting the characteristics of metals and carbon fiber reinforced composite material (CFRP) used as the material of the radio wave reflection layer 130.

Radar cross section (RCS) refers to the radar reflectance area and is calculated based on the electromagnetic signal from which the external radar signal is reflected back to the structure. The smaller the value of the RCS, the shorter the distance detected by the radar. Therefore, the RCS is an important measure of the performance of the stealth weapon system. Factors that determine the RCS include radar intensity, frequency, distance from the radar, the size and material of the object.

Referring to the graph of Fig. 8 (a), when electromagnetic waves of a predetermined frequency band (6 to 14 GHz) are incident perpendicularly to the entrance side A of the structure, the stealth structure shown in Fig. 7 (c) is closed oppositely. Although total reflection occurs from the side (B), it can be seen that it shows a lower RCS value than the stealth structure according to 7 (a) and (b).

On the other hand, referring to the graph of Fig. 8 (b), when the incident side is inclined at a predetermined angle with respect to the inlet side A of the structure, Figs. 7 (a) and 7 (b) show multiple reflections occurring inside the structure. It can be seen that due to the scattering effect, the difference between the RCS value and FIG. 7C is greater than that when the electromagnetic wave is vertically incident. That is, the stealth structure to which the double-sided wave absorber 100 according to the present embodiment is applied as shown in FIG. 7C is an advantageous structure for absorbing electromagnetic waves reflected and scattered in and out of the structure.

The double-sided wave absorber 100 according to the embodiment of the present invention described above has a similar symmetrical structure in which the wave absorbing layers 110 and 120 are formed on both surfaces of the wave reflecting layer 130 formed of a high strength and high rigidity material. When producing a three-dimensional stealth structure having a suppression of the generation of inter-layer distortion, there is an effect that can control the electromagnetic scattering elements by minimizing the exposure of the radio wave reflection layer (130).

Double-sided wave absorber 100 according to an embodiment of the present invention can be manufactured through a general composite manufacturing process. In detail, after stacking the materials forming each layer on the inner surface of the jig corresponding to the outer mold line (OML) in order, it can be manufactured by molding at a temperature of 120 ℃ to 150 ℃ and pressure conditions of 3 bar to 6 bar It is not limited to the said method.

In the above described exemplary embodiments of the present invention by way of example, the present invention is not limited to such specific embodiments, it can be carried out modified, changed or improved in various forms within the scope of the technical idea of the present invention. have.

100: double-sided wave absorber
110: first radio wave absorption layer
111: first high dielectric loss material layer
112: first low dielectric loss material layer
120: second wave absorption layer
121: second high dielectric loss material layer
122: second high dielectric loss material layer
130: radio wave reflection layer
140: adhesive layer

Claims (13)

In the radio wave absorber forming a stealth structure,
A first electromagnetic wave absorbing layer for absorbing incident electromagnetic waves in a first frequency band;
A second electromagnetic wave absorbing layer that absorbs incident electromagnetic waves of a second frequency band; And
A radio wave reflection layer formed between the first wave absorption layer and the second wave absorption layer to reflect the electromagnetic wave passing through the first wave absorption layer and the electromagnetic wave passing through the second wave absorption layer,
The radio wave reflecting layer is formed of a different thickness according to the load region of the stealth structure, double-sided wave absorber. The method of claim 1,
The second radio wave absorption layer is disposed to face the inside of the stealth structure,
The second frequency band absorbed by the second electromagnetic wave absorbing layer is a band lower than the first frequency band absorbed by the first electromagnetic wave absorbing layer. The method of claim 1,
And the radio wave reflection layer has a thickness thicker than at least the skin depth of the first frequency band and the second frequency band. delete The method of claim 1,
The first wave absorbing layer and the second wave absorbing layer is formed of a different thickness, double-sided wave absorber. The method of claim 1,
At least one of the first wave absorbing layer and the second wave absorbing layer is a double-sided wave absorber of which thickness is not constant. The method of claim 1,
The first radio wave absorption layer and the second radio wave absorption layer,
A low dielectric loss material layer whose one surface contacts the radio wave reflection layer; And
A double-sided electromagnetic wave absorber, one surface comprising a high dielectric loss material layer in contact with the other surface of the low dielectric loss material layer. The method of claim 7, wherein
Wherein said low dielectric loss material layer is formed of a foam core or glass fiber reinforced composite material (GFRP). The method of claim 7, wherein
The low dielectric loss material layer included in the first electromagnetic wave absorbing layer and the low dielectric loss material layer included in the second electromagnetic wave absorbing layer are different in thickness and material. The method of claim 7, wherein
The high dielectric loss material layer is provided with a sheet printed so that the conductive paste has an arbitrary pattern, double-sided wave absorber. The method of claim 10,
The high dielectric loss material layer included in the first radio wave absorption layer and the high dielectric loss material layer included in the second radio wave absorption layer are different in at least one of the shape of the pattern, the size of the pattern, the components of the paste, and the amount of the paste. , Double sided wave absorber. The method of claim 1,
A double-sided wave absorber further comprising an adhesive layer between the first wave absorbing layer, the wave reflecting layer, and the second wave absorbing layer and the wave reflecting layer. The method of claim 1,
The radio wave reflection layer is formed of an iron-aluminum based alloy, carbon fiber reinforced composite material (CFRP) or metal-based glass fiber reinforced composite material (GFRP), double-sided wave absorber.

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