KR102735433B1 - Lightweight electromagnetic wave absorber comprising Polygon Core Structure by conductive material and Manufacturing method thereof - Google Patents

Abstract

The present invention relates to a radio wave absorber manufactured using a lightweight material and a manufacturing method thereof. By forming a uniform metal layer on the outer surface of a fiber and the inner surface of a polygonal core structure using a large-scale multi-sputter gun deposition device on a fiber including a polygonal core structure, it is possible to manufacture a radio wave absorber which exhibits lightweight characteristics while also exhibiting an excellent electromagnetic wave shielding effect. The radio wave absorber manufactured using the radio wave absorber can be applied to various industries such as aircraft and marine.

Description

{Lightweight electromagnetic wave absorber comprising polygon core structure by conductive material and manufacturing method thereof}

The present invention relates to a radio wave absorber manufactured using a lightweight material and a method for manufacturing the same.

Stealth functions essential to various weapon systems in modern warfare can be largely classified into three categories: shaping technology, radar absorbing material (RAM), and radar absorbing structure (RAS). Shaping technology is the basic technology of stealth technology that scatters electromagnetic waves incident on a weapon system in a direction other than the direction of incidence. However, due to recent developments in radar technology, shape design alone has limitations in ensuring the survivability of weapon systems. To overcome this, electromagnetic wave absorbing materials that apply electromagnetic wave absorbing materials to the structural surface of weapon systems in a similar manner, such as painting, have been developed, but they have poor durability, require periodic maintenance, and are heavy, which reduces aircraft performance. Accordingly, research on various electromagnetic wave absorbing structures is actively being conducted. Electromagnetic wave absorbing structures were initially developed to be composed of inorganic materials and have strong hardness, but they have problems such as strong hardness, risk of breakage, and heavy weight. Recently, a structure in which a material having nano particle loss, such as carbon nanotubes, carbon black, or carbon nanofibers, is added to the matrix, or a radio wave absorber that can eliminate uncertainties such as non-uniform distribution by coating metals on porous fibers (such as glass fibers or honeycombs) has been used. Korean Patent Publication No. 10-1744623 discloses a method of manufacturing the fiber by immersing it in a plating solution; however, this method is disadvantageous in forming a uniform coating layer, and Korean Patent Publication No. 10-2483727 describes a step of vacuum depositing a metal coating layer on a dielectric fabric material; however, this method has a disadvantage in that a uniform metal coating layer cannot be formed in the pores of the porous dielectric fabric material. Therefore, research is needed on a radio wave absorbing structure that is uniformly coated even inside the pores while using a porous lightweight material, and a method for manufacturing such a radio wave absorbing structure.

Korean Patent Publication No. 10-2105136 (2020.04.27) Korean Patent Publication No. 10-2483727 (2022.12.28)

The present invention provides a method for uniformly coating a conductive metal on the inner surface of a large-area fiber having a polygonal core structure.

The present invention provides a radio wave absorbing structure including a radio wave absorbing material having a polygonal core structure uniformly coated with a conductive metal, and a manufacturing method capable of manufacturing a lightweight radio wave absorbing structure having a sandwich structure including the radio wave absorbing material over a large area through a simple process.

The present invention provides a method for manufacturing a radio wave absorbing material, which comprises the step of forming a uniform conductive metal layer on the outer surface of a fiber and the inner surface of a polygonal core structure using a large-area multi-sputter gun deposition device on a large-area fiber including a polygonal core structure.

In one example of the present invention, the radio wave absorbing material can satisfy the following equation 1.

Equation 1

(t0 is the average thickness of the conductive metal formed on the outer surface of the fiber, t1 is the average thickness of the conductive metal formed on the inner surface of the polygonal core from one side of the fiber to a point 1/2h of the width direction length when the length in the width direction of the fiber is h, t2 is the average thickness of the conductive metal formed on the inner surface of the polygonal core from a point 1/2h of the width direction length to the other side of the fiber)

In one example of the present invention, the thickness of the conductive metal formed on the outer surface of the large-area fiber may be 300 to 10,000 nm.

In one example of the present invention, the conductive metal may be one or more selected from TIO, Ti, TiN, ZnO, FTO, Cr, Ni, and Al.

In one example of the present invention, the partial pressure ratio of argon and oxygen in the sputtering gun deposition device may be 5 to 1:1.

In one example of the present invention, the substrate temperature of the sputtering gun deposition device may be 200 to 500°C.

law.

In one example of the present invention, the power of the sputtering gun deposition device may be 5 to 50 W.

In one example of the present invention, the fiber may be an aramid honeycomb.

The present invention provides a radio wave absorbing material comprising: a large-area fiber including a polygonal core structure; and a conductive metal layer on an outer surface of the fiber including the polygonal core structure and an inner surface of the polygonal core structure; wherein the thickness of the conductive metal layer formed on the outer surface of the polygonal core structure is 300 to 10,000 nm, and the thickness of the conductive metal layer formed on the inner surface of the polygonal core structure satisfies the following Equation 1.

Equation 1

(t0 is the average thickness of the conductive metal formed on the outer surface of the fiber, t1 is the average thickness of the conductive metal formed on the inner surface of the polygonal core from one side of the fiber to a point 1/2h of the width direction length when the length in the width direction of the fiber is h, t2 is the average thickness of the conductive metal formed on the inner surface of the polygonal core from a point 1/2h of the width direction length to the other side of the fiber)

In one example of the present invention, the fiber may be an aramid honeycomb.

The present invention provides a method for manufacturing a lightweight radio wave absorbing structure, comprising the steps of: a) preparing a reflective layer; b) laminating a dielectric layer on the reflective layer; c) laminating a radio wave absorbing material of claim 8 on the dielectric layer; and d) laminating a dielectric layer on the radio wave absorbing material.

In one example of the present invention, steps c) and d) may be performed two or more times as a unit process.

In one example of the present invention, the dielectric layer may be at least one selected from the group consisting of glass fiber reinforced plastic and carbon fiber reinforced plastic.

In one example of the present invention, the reflective layer may include at least one selected from the group consisting of iron, aluminum, copper, and conductive carbon.

The present invention forms a conductive metal layer by depositing a conductive metal on a large-area fiber having a polygonal core structure using a multi-large sputter gun vacuum deposition device, thereby forming a metal layer with a uniform thickness not only on the outer surface but also on the inner surface of the fiber.

A radio wave absorbing structure including a radio wave absorbing material manufactured by a manufacturing method according to the present invention exhibits lightweight characteristics while having excellent electromagnetic wave shielding performance against electromagnetic waves incident from the side and inside.

Figure 1 is a schematic diagram of a lightweight radio wave absorbing structure according to an embodiment of the present invention.
Figure 2 is a graph showing the electromagnetic wave shielding performance of a lightweight radio wave absorbing structure according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail so that a person having ordinary knowledge in the technical field to which the present invention belongs can easily practice it. However, this means that the present invention can be implemented in various different forms and is not limited to the implementation examples described herein. Also, it is not intended to limit the scope of protection defined by the patent claims.

In addition, unless otherwise defined, technical and scientific terms used in the description of the present invention have meanings commonly understood by a person of ordinary skill in the art to which this invention pertains, and descriptions of well-known functions and configurations that may unnecessarily obscure the gist of the present invention are omitted in the following description.

The numerical range used in this specification includes the lower and upper limits and all values within that range, increments logically derived from the shape and width of the defined range, all doubly defined values, and all possible combinations of the upper and lower limits of a numerical range defined in different shapes. Unless otherwise specifically defined in the specification of the present invention, values outside the numerical range that may arise due to experimental error or rounding of values are also included in the defined numerical range.

Unless otherwise specifically defined in this invention, the statement that a part "includes" a certain component does not exclude other components unless specifically stated to the contrary, but rather means that it may further include other components. In addition, the singular forms used in the specification and the appended claims are intended to include the plural forms as well, unless the context clearly indicates otherwise.

In this specification, units used unless otherwise specified are based on weight, and for example, units of % or ratio mean weight% or weight ratio, and weight% means the weight % that one component occupies in the composition among the entire composition unless otherwise defined.

The term "substantially not used", as used herein, means that other elements, materials or processes not listed with the specified element, material or process may be present in amounts that do not unacceptably significantly affect at least one basic and novel technical idea of the invention.

Conventional radio wave absorbing structures are manufactured by coating a matrix including a nanostructure on a conductive metal to increase radio wave absorbency, or by coating a conductive metal on fibers having a space inside for the purpose of lightness. However, radio wave absorbing structures manufactured by immersing in conductive metal had problems due to weight when applied to aircraft, etc., and radio wave absorbing structures manufactured by coating a conductive metal on fibers having a space inside had a problem that it was difficult to uniformly coat a conductive line metal over a large area in units of meters due to limitations in the area that could be manufactured. Accordingly, the inventors of the present invention have developed a method for forming a uniform conductive metal coating on a large-area lightweight fiber having a space inside while maintaining a lightweight characteristic, and a lightweight radio wave absorbing structure including the same.

The present invention provides a method for manufacturing a radio wave absorber, comprising the step of forming a uniform conductive metal layer on the outer surface of a fiber and the inner surface of a polygonal core structure using a large multi-sputter gun deposition device on a fiber including a polygonal core structure.

The method for manufacturing a radio wave absorbing material of the present invention uses a method of forming a conductive metal layer on a fiber by depositing a conductive metal using a large multi-sputter gun vacuum deposition device, thereby having the effect of forming a uniform conductive metal layer over a large area.

In addition, when manufacturing a radio wave absorbing material using the manufacturing method of the present invention, a conductive metal having a uniform thickness is deposited not only on the outer surface of the fiber but also on the inner surface of the fiber including the polygonal core, compared to the prior art, thereby exhibiting lightweight characteristics while also exhibiting sufficient radio wave shielding performance.

In addition, when using the large-scale multi-sputter gun of the present invention, while commercially available fibers have lengths in the order of cm, uniform deposition can be achieved even on large-area fibers in the order of meters, so when mass-producing radio wave absorbers, there is a process advantage in that radio wave absorbers with uniform electromagnetic performance can be produced through a simple process.

In one embodiment, when a conductive metal is deposited on a fiber including a polygonal core using the method for manufacturing a radio wave absorbing material according to the present invention, when an average thickness of a conductive metal layer formed on an outer surface of the fiber including the polygonal core is t0 and a length in the width direction of the fiber is h, when an average thickness of a conductive metal layer formed on the inner surface of the polygonal core from one side of the fiber to a point 1/2h in the width direction is t1, and an average thickness of a conductive metal layer formed on the inner surface of the polygonal core of the fiber from a point 1/2h in the width direction to the other side of the fiber is t2, the following Equation 1 is satisfied.

Equation 1

In one embodiment, the average thickness of the conductive metal formed on the outer surface of the fiber including the polygonal core may be, but is not limited to, 100 to 10,000 nm, 100 to 1,000 nm, or 300 to 900 nm, and thus may be adjusted within the above-described range depending on process conditions. By using the method for manufacturing a radio wave absorbing material according to the present invention, a uniform conductive metal layer at the nanometer level can be uniformly deposited even on a large-area fiber having a polygonal core structure or an internal space in the unit of meters. In the past, a method of immersing a fiber including an internal space in a plating bath was used, but while this method enabled coating to be performed on the internal space of the conductive fiber including the internal space, it could not impart a uniform coating thickness and lightweight characteristics to a large area. In addition, when electrical plating is used, there is a limit to the area that can be coated, so that coating over a large area was not possible, making mass production impossible. However, by using the method for manufacturing a radio wave absorbing material according to the present invention, a uniform metal coating layer can be formed on a fiber including an internal space, and there is an advantage in that a uniform coating layer can be formed even over a large area.

In one embodiment, the substrate temperature of the large-scale multi-sputter gun deposition device may be 100 to 600° C., specifically 200 to 500° C. The temperature of the substrate may be appropriately controlled depending on the type of conductive metal to be deposited and the type of crystal formed by the deposition, but is not limited thereto.

In one embodiment, the gas supplied to the large-scale multi-sputter gun deposition device includes argon and oxygen, and the pressure of the entire gas may be 1 to 20 torr, specifically 1 to 10 torr, but is not limited thereto. Specifically, the partial pressure ratio of argon to oxygen in the gas may be 10 to 1:1, specifically 5 to 1:1. When the partial pressure ratio of argon to oxygen satisfies the above range, an appropriate sputtering speed can be maintained, while the conductive metal layer can exhibit excellent thin film characteristics.

In one embodiment, the power of the large-scale multi-sputter gun deposition device may be 10 to 100 W, specifically 20 to 50 W, but is not limited thereto, and the sputtering power may be appropriately adjusted depending on the type of target metal. The content of the conductive metal included in the conductive metal coating layer varies depending on the sputtering power, and accordingly, the electromagnetic wave absorption rate of the radio wave absorbing material can be adjusted to a desired level.

The fiber including the polygonal core structure is not limited if the core includes a hollow space penetrating from one side of the fiber to the other side in the shape of a polygonal column or a cylinder, or a form that forms a space by forming a void inside, but in cases where lightweight characteristics are required, it may be preferable to include a core structure penetrating the fiber. The form that forms a space by forming a void inside may be specifically a foamed plastic, and the form including the core structure penetrating the fiber may be a honeycomb structure including hexagonal cells. When the fiber includes the honeycomb structure, it has the effect of forming a space inside while exhibiting very high structural stability, which is advantageous for application to aircraft, etc. The honeycomb may have a specification in which the diameter of one hexagon is 1/16" (about 1.59 mm) to 2" (about 4.54 mm), specifically, 1/8" (about 3.175 mm) to 3/16" (about 4.76 mm), but is not limited thereto.

The conductive metal may be at least one selected from TiO, Ti, TiN, ZnO, FTO, Cr, Ni, and Al. Since the radio wave absorbing material of the present invention deposits the conductive metal on a fiber including a polygonal core structure, the dielectric fiber without electrical conductivity or electromagnetic properties can exhibit electromagnetic wave absorption performance. In addition, since both the outer surface and the inner surface of the fiber are uniformly coated with the conductive metal, the fiber can exhibit a reduction effect on electromagnetic waves incident on the interior or side surface. Since such a radio wave absorbing material is included in a multilayered radio wave absorbing structure such as a sandwich structure, the reduction efficiency on electromagnetic waves incident on the side surface can be maximized.

The present invention provides a radio wave absorbing material comprising: a fiber including a polygonal core structure; and a conductive metal layer formed on an outer surface of the fiber including the polygonal core structure and an inner surface of the polygonal core structure; wherein the thickness of the conductive metal layer formed on the outer surface of the fiber including the polygonal core structure is 300 to 1000 nm, and the thickness of the conductive metal layer formed on the inner surface of the polygonal core structure satisfies the following Equation 1.

Equation 1

(t0 is the average thickness of the conductive metal layer formed on the outer surface of the fiber, t1 is the average thickness of the conductive metal layer formed on the inner surface of the polygonal core from one side of the fiber to a point 1/2h of the width direction length when the length in the width direction of the fiber is h, t2 is the average thickness of the conductive metal layer formed on the inner surface of the polygonal core from a point 1/2h of the width direction length to the other side of the fiber)

The above-described radio wave absorbing material can provide a radio wave absorbing material that is lightweight and has significantly improved radio wave absorption capability, in which a uniform nanometer-level conductive metal layer is formed on the outer and inner surfaces of a fiber including a polygonal core structure. Such a lightweight material has the effect of being usefully applied to radio wave absorbing structures used in various industries that require lightweight characteristics, such as aircraft and ships.

The types of the polygonal core structure, fibers, and conductive metals are the same as those described above, so detailed descriptions are omitted.

The present invention provides a method for manufacturing a lightweight radio wave absorbing structure, comprising the steps of: a) preparing a reflective layer; b) laminating a dielectric layer on the reflective layer; c) laminating the above-described radio wave absorbing material on the first dielectric layer; and d) laminating a dielectric layer on the radio wave absorbing material.

The above lightweight radio wave absorbing structure can exhibit an electromagnetic wave shielding performance improvement effect and a lightweight effect by including the above-described radio wave absorbing material, thereby improving the absorption performance for electromagnetic waves incident from the side and inside.

The present invention can be performed twice or more with steps c) and d) as unit processes. By repeatedly performing steps c) and d) as unit processes, a lightweight radio wave absorbing structure can be manufactured with a sandwich structure. Specifically, when the unit processes are performed twice, the lightweight radio wave absorbing structure can be provided in which a reflective layer, a dielectric layer, a radio wave absorbing material, a dielectric layer, a radio wave absorbing material, and a dielectric layer are laminated in that order. The lightweight radio wave absorbing structure according to the present invention is a structure in which a sandwich structure is formed in the related art in order to improve electromagnetic shielding performance, but the weight increases as a result, making it difficult to apply it to aircraft and the like that require electromagnetic shielding performance. However, the radio wave absorbing structure of the present invention can maintain lightweight characteristics compared to a related art radio wave absorbing structure even when manufactured with a sandwich structure, and thus can exhibit a more remarkable effect, especially when manufactured with a sandwich structure.

The above reflection layer may be a material having excellent strength for supporting the structure while exhibiting the effect of reflecting electromagnetic waves that have passed through the dielectric layer and the electromagnetic wave absorbing layer and inducing reabsorption. Specifically, the reflection layer is advantageous if it is a material that can completely reflect electromagnetic waves, and more specifically, may include at least one selected from the group consisting of iron, aluminum, copper, and conductive carbon.

The dielectric layer may include at least one fiber-reinforced plastic selected from the group consisting of glass fiber-reinforced plastic and carbon fiber-reinforced plastic. The fiber-reinforced plastic may further include at least one conductive material selected from the group consisting of carbon nanotubes, carbon fibers, graphene, and reduced graphene oxide. Accordingly, incident electromagnetic waves can be absorbed to reduce the intensity of the electromagnetic waves, and thereafter, unabsorbed electromagnetic waves can be absorbed by the radio wave absorbing material or reflected by the reflective layer and reabsorbed.

The thickness of the above dielectric layer may be 1 to 5 mm, specifically 1 to 3 mm, and when the dielectric layer satisfies the above thickness, it can exhibit optimal electromagnetic wave absorption characteristics in the X-band (8.2 to 12.4 GHz), which is a military radar frequency band.

Example 1

An electromagnetic wave absorbing material was manufactured by forming a conductive metal layer of TiN on a 2 X 2 m sized polyaramid honeycomb (honeycomb diameter 1/8" (approximately 3.175 mm), cell wall thickness 0.05 mm) using a large multi-sputter gun vacuum deposition device. At this time, TiN was used as the target, oxygen and argon were used as sputtering gases, the partial pressure was 5:1, and the substrate temperature was set to 300°C. The thicknesses of the conductive metal layers deposited on the outer and inner surfaces of the polyaramid honeycomb at this time are shown in Table 1 below.

Example 2

The same procedure as in Example 1 was followed, except that the size of the polyaramid honeycomb was set to 1 X 1 (m). The thicknesses of the conductive metal layers deposited on the outer and inner surfaces of the polyaramid honeycomb are shown in Table 1 below.

Example 3

The same procedure as in Example 1 was followed except that a Ti metal layer was formed. The thicknesses of the conductive metal layers deposited on the outer and inner surfaces of the polyaramid honeycomb are shown in Table 1 below.

Comparative Example 1

Example 1 The polyaramid honeycomb was formed with a conductive metal layer using a single sputter gun vacuum deposition device to manufacture an electromagnetic wave absorbing material. At this time, TiN was used as a target, oxygen and argon were used as sputtering gases, the partial pressure was 5:1, and the substrate temperature was set to 300°C. At this time, the thickness of the conductive metal layer deposited on the outer and inner surfaces of the polyaramid honeycomb is shown in Table 1 below.

Comparative Example 2

Example 1 The polyaramid honeycomb was formed with a conductive metal layer using a single sputter gun vacuum deposition device to manufacture an electromagnetic wave absorbing material. At this time, Ti was used as the target, oxygen and argon were used as sputtering gases, the partial pressure was 5:1, and the substrate temperature was set to 300°C. At this time, the thickness of the conductive metal layer deposited on the outer and inner surfaces of the polyaramid honeycomb is shown in Table 1 below.

Thickness (nm) Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Fiber outer surface (t0) 457 450 447 463 467 t2 449 448 446 387 391 t1 434 437 439 324 314 3.2 2.4 1.50 13.6 16.4

Examples 1 to 3, in which a conductive metal layer was formed using a large-scale multi-sputter gun vacuum deposition device, confirmed that the conductive metal was evenly deposited on both the inner and outer surfaces of the polygonal core fiber, with the values of Equation 1 being 3.2, 2.4, and 1.5, respectively. In contrast, when a large-area conductive metal was deposited on the cross-section using a single sputter gun, not only was the conductive metal not evenly formed on the outer surface of the fiber, but the thickness difference between the inner surface of the fiber and the polygonal core was 50 nm or more.

Manufacturing example 1

An aluminum plate was used as a reflective layer, and a glass fiber reinforced plastic containing carbon nanotubes was used as a dielectric layer. A lightweight radio wave absorber was manufactured by sequentially laminating the reflective layer, the dielectric layer, the radio wave absorber of Example 1, the dielectric layer, the radio wave absorber of Example 1, and the dielectric layer.

Manufacturing example 2

An aluminum plate was used as a reflective layer, and a glass fiber reinforced plastic containing carbon nanotubes was used as a dielectric layer. A lightweight radio wave absorber having a sandwich structure was manufactured by sequentially laminating a reflective layer, a dielectric layer, a radio wave absorber of Example 2, a dielectric layer, a radio wave absorber of Example 2, and a dielectric layer.

Experimental Example 1

The X-band (8.2 to 12.4 GHz) electromagnetic wave shielding capability was tested using the lightweight radio wave absorbers manufactured in Manufacturing Examples 1 and 2.

Referring to Fig. 1, it can be seen that a radio wave absorption performance of -10 dB or higher is realized in the X-band (8.2 to 12.4 GHz), which is a military radar frequency band. That is, it was confirmed that the radio wave absorbing structure of the present invention exhibits excellent electromagnetic wave shielding performance in the X-band region while providing lightweight characteristics.

Claims (14)

A method of forming a uniform conductive metal layer on a large-area fiber including a polygonal core structure by using a large-scale multi-sputter gun deposition device, the method comprising:
A method for manufacturing a radio wave absorbing material satisfying the following equation 1.
Equation 1

(t0 is the average thickness of the conductive metal layer formed on the outer surface of the fiber, t1 is the average thickness of the conductive metal layer formed on the inner surface of the polygonal core from one side of the fiber to a point 1/2h of the width direction length when the width direction length of the fiber is h, t2 is the average thickness of the conductive metal layer formed on the inner surface of the polygonal core from a point 1/2h of the width direction length to the other side of the fiber) delete In the first paragraph,
A method for manufacturing a radio wave absorbing material, wherein the thickness of the conductive metal layer formed on the outer surface of the large-area fiber is 300 to 10,000 nm. In the first paragraph,
A method for manufacturing a radio wave absorbing material, wherein the conductive metal layer is at least one selected from TIO, Ti, TiN, ZnO, FTO, Cr, Ni, and Al. In the first paragraph,
A method for manufacturing a radio wave absorbing material, wherein the partial pressure ratio of argon and oxygen in the above large multi-sputter gun deposition device is 5 to 1:1. In the first paragraph,
A method for manufacturing a radio wave absorbing material, wherein the substrate temperature of the large-scale multi-sputter gun deposition device is 200 to 500°C. In the first paragraph,
A method for manufacturing a radio wave absorbing material, wherein the power of the large-scale multi-sputter gun deposition device is 5 to 50 W. In the first paragraph,
A method for manufacturing a radio wave absorbing material, wherein the above fiber is an aramid honeycomb. A radio wave absorbing material comprising: a large-area fiber including a polygonal core structure; and a conductive metal layer on an outer surface of the fiber including the polygonal core structure and an inner surface of the polygonal core structure; wherein the thickness of the conductive metal layer formed on the outer surface of the polygonal core structure is 300 to 10,000 nm, and the thickness of the conductive metal layer formed on the inner surface of the polygonal core structure satisfies the following Equation 1.
Equation 1

(t0 is the average thickness of the conductive metal layer formed on the outer surface of the fiber, t1 is the average thickness of the conductive metal layer formed on the inner surface of the polygonal core from one side of the fiber to a point 1/2h of the width direction length when the length in the width direction of the fiber is h, t2 is the average thickness of the conductive metal layer formed on the inner surface of the polygonal core from a point 1/2h of the width direction length to the other side of the fiber) In Article 9,
The above fiber is an aramid honeycomb, radio wave absorbing material. a) Step of preparing a reflective layer;
b) a step of laminating a dielectric layer on the reflective layer;
c) a step of laminating the radio wave absorbing material of claim 9 on the dielectric layer; and
d) A method for manufacturing a lightweight radio wave absorbing structure, comprising the step of laminating a dielectric layer on the radio wave absorbing material. In Article 11,
The above steps c) and d) are performed twice or more as a unit process.
A method for manufacturing a lightweight radio wave absorbing structure.
In Article 11,
A method for manufacturing a lightweight radio wave absorbing structure, wherein the dielectric layer of steps b) and d) is at least one selected from the group consisting of glass fiber reinforced plastic and carbon fiber reinforced plastic. In Article 11,
A method for manufacturing a lightweight radio wave absorbing structure, wherein the reflective layer comprises at least one selected from the group consisting of iron, aluminum, copper, and conductive carbon.