Wave-absorbing structure based on microfilament filling paper-based material

Abstract

The invention belongs to the technical field of wave-absorbing bodies, and relates to a wave-absorbing structure based on a microfilament filling paper-based material, which comprises a paper-based layer and a dielectric layer which are overlapped from top to bottom, the paper-based layer comprises a plurality of microfilaments and a paper-based material, the paper-based material is filled with the microfilaments, and the dielectric layer and the paper-based layer are subjected to impedance matching; adjusting the length and / or the surface density of the microfilaments so as to adjust the working frequency band of the wave-absorbing structure; the plurality of microfilaments are randomly filled in the paper-based material, so that the distribution directions of the microfilaments are random; the plurality of microfilaments are filled in the paper-based material in order, so that the distribution directions of the microfilaments are ordered; the distribution directions of all the microfilaments are consistent; and the length directions of all the microfilaments are parallel to a group of opposite sides of the paper base layer. According to the invention, on the premise of not changing the thickness of the wave-absorbing structure, the absorption strength is improved, the range of designable frequency bands is expanded, and the electromagnetic absorption mechanisms are diversified.

Description

Technical Field

[0001] The present application relates to the technical field of wave absorbing bodies, and in particular to a wave absorbing structure based on microfilament-filled paper-based materials. Background Art

[0002] With the development of science and technology, electronic devices have been widely used, which greatly facilitates people's lives. However, a large amount of electromagnetic radiation pollution has also been generated, causing mutual interference between electronic devices and threatening human life and health. In addition, the detection technology of radio equipment has developed rapidly. In order to reduce the possibility of equipment being detected and tracked, it is necessary to achieve electromagnetic stealth of equipment. Electromagnetic wave absorbing materials can effectively dissipate incident electromagnetic waves. Therefore, electromagnetic wave absorbing materials are of great significance in reducing electromagnetic radiation pollution in the environment and achieving electromagnetic stealth of equipment.

[0003] In the prior art, electromagnetic wave absorbing materials mainly include: metamaterial absorbers and filled absorbing materials.

[0004] Metamaterial absorbers are generally designed by designing metal units of different shapes on a dielectric substrate, and using the resonance effect of the metal units to absorb electromagnetic waves, but the absorption mechanism is single; to achieve low-frequency absorption, it is often necessary to increase the thickness of the dielectric, and the density of the absorber formed is relatively large, which cannot meet the requirements for the thinness of the absorber material. In addition, if you want to adjust the electromagnetic wave absorption band range when the thickness of the dielectric substrate is fixed, you often need to change the size of the structure, but while ensuring strong absorption, the adjustable range of the absorption band range by changing the size of the structure is often narrow, so it is generally necessary to redesign the unit structure pattern, which is time-consuming and labor-intensive.

[0005] Filling-type absorbing materials include electric loss type and magnetic loss type materials, typical of which are graphene and carbonyl iron powder. However, absorbing materials made of a single loss material as a filler have problems such as poor impedance matching, narrow absorption band, single absorption mechanism, and weak absorption intensity, which limit their application. Therefore, materials with multiple loss mechanisms are usually filled, and multiple electromagnetic absorption mechanisms are used to respond synergistically to achieve better impedance matching and stronger and wider-band electromagnetic absorption. However, composite materials filled with multiple loss materials also often have high density, and the band design depends on changing the thickness, especially the thickness needs to be increased to achieve low-frequency absorption.

[0006] Therefore, existing electromagnetic wave absorbing materials cannot meet the diverse and comprehensive requirements of equipment for absorbing materials / structures that are light and thin, simple and flexible to control, and easy to conform to. Summary of the invention

[0007] Based on this, it is necessary to provide an absorbing structure based on microwire-filled paper-based materials to address the above-mentioned technical problems. This structure can ensure strong absorption characteristics without changing the thickness of the absorber, and at the same time achieve simple and flexible design within a wide bandwidth by regulating the length and surface density of the filled microwires. It also has diverse electromagnetic absorption mechanisms and has the advantages of being light, flexible and conformable, with flexible and simple frequency band design, and a wide designable frequency band range.

[0008] A wave absorbing structure based on a microwire-filled paper-based material, comprising: a paper base layer and a dielectric layer stacked from top to bottom; The paper base layer includes a plurality of microwires and a paper base material, the plurality of microwires are filled inside the paper base material, and the dielectric layer and the paper base layer are impedance matched; The length and / or surface density of the microwires are adjusted to adjust the working frequency band of the wave absorbing structure.

[0009] In one embodiment, a plurality of the microwires are randomly filled in the paper-based material, so that the distribution direction of the microwires is random.

[0010] In one embodiment, a plurality of the microwires are orderly filled in the paper-based material, so that the distribution direction of the microwires is orderly.

[0011] In one embodiment, all microwires are distributed in the same direction.

[0012] In one embodiment, the length directions of all microwires are parallel to a set of opposite sides of the paper substrate.

[0013] In one embodiment, all the microwires are distributed in two directions, which are respectively parallel to a set of adjacent sides of the paper base layer.

[0014] In one embodiment, the material of the microwire is glass-coated Co 72 Fe5Si8B 15 Amorphous alloy microwires.

[0015] In one embodiment, the material of the medium layer is PMI foam or air.

[0016] In one embodiment, it further comprises: a floor layer; The floor layer is arranged on the lower surface of the medium layer to be connected with external equipment.

[0017] The above-mentioned absorbing structure based on microwire-filled paper-based material is designed with overlapping paper-based layers and dielectric layers. By adjusting the length and / or surface density of the microwires, the impedance of the paper-based layer can be changed, so that the impedance matching performance of different frequency bands is better, thereby improving the absorption intensity without changing the thickness of the absorbing structure (especially the thickness of the dielectric layer) and without considering the structural pattern, achieving strong absorption of low and high frequencies (below -10dB), and adjusting the working frequency band of the absorbing structure at the same time to achieve impedance matching in different frequency bands, thereby expanding the range of designable frequency bands, achieving broadband electromagnetic absorption, and supporting flexible and simple design and regulation of absorbing structures within the broadband absorbing frequency band. The present application belongs to a composite material, and multiple loss mechanisms work together instead of relying on a single electrical loss or magnetic loss, which solves the problem of a single absorption mechanism in the prior art. In addition, the present application has the characteristics of simple structure, low density, light weight, thin thickness, low cost, flexibility, and can be designed conformally with curved surfaces, which has significant advantages in a wide range of application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A three-dimensional schematic diagram of a wave absorbing structure based on a microwire-filled paper-based material in an embodiment in a state where the microwires are randomly filled; Figure 2 A schematic side view of a wave absorbing structure based on a microwire-filled paper-based material in an embodiment in a state where the microwires are randomly filled; Figure 3 A three-dimensional schematic diagram of a wave absorbing structure based on a microwire-filled paper-based material in an embodiment in a state where the microwires are orderly filled; Figure 4 A schematic side view of a wave absorbing structure based on a microwire-filled paper-based material in an embodiment in a state where the microwires are orderly filled; Figure 5 Result diagram of reflection coefficient of a wave absorbing structure based on microwire-filled paper-based material under different surface densities when the microwire length is 8 mm in one embodiment; Figure 6 Result diagram of reflection coefficient of a wave absorbing structure based on microwire-filled paper-based material under different surface densities when the microwire length is 6 mm in one embodiment; Figure 7 Result diagram of reflection coefficient of a wave absorbing structure based on microwire-filled paper-based material under different surface densities when the microwire length is 4 mm in one embodiment; Figure 8 A graph showing the reflection coefficient results of a wave absorbing structure based on a microwire-filled paper-based material in an embodiment, in which the microwire length is 200 mm and the surface density is different to achieve TE polarization; Fig. 9This is a graph showing the reflection coefficient results of a wave absorbing structure based on microwire-filled paper-based material in an embodiment, which realizes TM polarization at different surface densities when the microwire length is 200 mm.

[0019] Reference numerals: Paper base layer 1, medium layer 2, floor layer 3. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0021] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0022] In addition, the descriptions of "first", "second", etc. in this application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "multiple groups" means at least two groups, such as two groups, three groups, etc., unless otherwise clearly and specifically defined.

[0023] In this application, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0024] In addition, the technical solutions between the various embodiments of the present application can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0025] The present application provides a wave absorbing structure based on a microwire-filled paper-based material. In one embodiment, the structure includes: a paper base layer and a dielectric layer.

[0026] The paper base layer and the medium layer are stacked from top to bottom, and the paper base layer is the same size as the medium layer.

[0027] The paper base layer includes: a plurality of microwires and a paper base material. The lengths of all the microwires can be the same or different, the surface densities of all the microwires can be the same or different, and all the microwires are randomly filled inside the paper base material.

[0028] The impedance matching between the dielectric layer and the paper base layer is optimized. Specifically, impedance matching is achieved with the paper base layer by changing the thickness of the dielectric layer. For example, if the impedance of the upper paper base layer is capacitive, the impedance of the lower layer is designed to be inductive, thereby achieving impedance matching in a specific frequency band, allowing electromagnetic waves to enter the material to the maximum extent and be lost instead of being reflected, thereby achieving efficient absorption of the incident electromagnetic waves.

[0029] In this embodiment, the length and / or surface density of the microwires are adjusted to adjust the working frequency band of the absorbing structure without changing the thickness of the dielectric layer, so as to achieve impedance matching in different frequency bands, thereby supporting flexible and simple design and regulation of the absorbing structure within the broadband absorbing frequency band. Specifically: the shorter the length of the microwire, the better the impedance matching at high frequencies; the longer the length of the microwire, the better the impedance matching at low frequencies; the smaller the surface density of the microwire, the better the impedance matching at high frequencies; the larger the surface density of the microwire, the better the impedance matching at low frequencies.

[0030] Preferably, a plurality of microwires are randomly filled in the paper-based material, so that the distribution direction of the microwires is random (they can be arranged crosswise or spaced apart), such as Figure 1 and Figure 2 shown.

[0031] Further preferably, a plurality of microwires are orderly filled in the paper-based material, so that the distribution direction of the microwires is orderly (they can be arranged crosswise or spaced apart), such as Figure 3 and Figure 4 shown.

[0032] More preferably, the plurality of microwires are distributed in an orderly and uniform manner to balance the performance of the absorbing structure under different conditions.

[0033] More preferably, all microwires are distributed in the same direction to further increase the absorption intensity and expand the range of designable frequency bands.

[0034] More preferably, the length directions of all microwires are parallel to a set of opposite sides of the paper substrate to achieve a linear polarization state; or, the length directions of all microwire structures are parallel to another set of opposite sides of the paper substrate to achieve another linear polarization state.

[0035] More preferably, all the microwires have two distribution directions which are respectively parallel to a set of adjacent edges of the paper base layer, so as to realize two polarization states simultaneously.

[0036] In another embodiment, it also includes: a floor layer; that is, the absorbing structure includes: a paper base layer, a dielectric layer and a floor layer stacked in sequence from top to bottom; the floor layer is arranged on the lower surface of the dielectric layer, and is made of metal material to be connected to an external device; the external device can be a device to be processed for electromagnetic compatibility or equipment to be processed for stealth, such as: the surface of an aircraft.

[0037] In this application, the materials used for the microwire, paper-based material, dielectric layer and floor layer are all prior art and will not be described in detail. 72 Fe5Si8B 15 Amorphous alloy microfilament, the paper base material is sticky printing paper, the medium layer is PMI foam or air, and the floor layer is copper.

[0038] The present application designs a paper base layer and a dielectric layer, which have multiple electromagnetic absorption mechanisms and a fixed thickness, to form an absorbing structure whose absorption band can be flexibly and simply designed, and has the advantages of being thin and light.

[0039] Specifically: First, since the internal alloy components of the microwire material are metal alloys, although non-conductive materials are doped, the overall electrical conductivity is still relatively high; when electromagnetic waves are incident on the paper base layer, they will stimulate current in the metal alloy inside the microwire, thereby generating electrical resonance, and part of the electromagnetic waves will be converted into Joule heat energy due to the electrical loss caused by the electromagnetic resonance.

[0040] Second, the metal alloy contains cobalt, which is a typical magnetic material. By adding cobalt to the conductive material, the electrical conductivity of the material can be reduced, so that the impedance of the material and the free space is better matched, which is conducive to the absorption of electromagnetic waves. In addition, the high magnetic permeability and magnetic tension of cobalt can effectively enhance the magnetic loss of the microwire.

[0041] Third, the designed structure causes electromagnetic waves to be reflected and scattered multiple times in its internal spatial structure, thereby effectively enhancing the electromagnetic absorption effect.

[0042] Fourth, by designing the length and surface density of the microwires, the impedance characteristics of the paper base layer are improved, thereby adjusting the impedance characteristics of the entire structure to move to a specific frequency band, achieving a flexible and simple design of the absorbing frequency band.

[0043] Fifth, the designed structure has excellent impedance matching characteristics, achieving impedance matching within a specific frequency band, introducing an effect similar to circuit series resonance, and achieving strong absorption.

[0044] The above-mentioned absorbing structure based on microwire-filled paper-based material is designed with overlapping paper-based layers and dielectric layers. By adjusting the length and / or surface density of the microwires, the impedance of the paper-based layer can be changed, so that the impedance matching performance of different frequency bands is better, thereby improving the absorption intensity without changing the thickness of the absorbing structure (especially the thickness of the dielectric layer) and without considering the structural pattern, achieving strong absorption of low and high frequencies (below -10dB), and adjusting the working frequency band of the absorbing structure at the same time to achieve impedance matching in different frequency bands, thereby expanding the range of designable frequency bands, achieving broadband electromagnetic absorption, and supporting flexible and simple design and regulation of absorbing structures within the broadband absorbing frequency band. The present application belongs to a composite material, and multiple loss mechanisms work together instead of relying on a single electrical loss or magnetic loss, which solves the problem of a single absorption mechanism in the prior art. In addition, the present application has the characteristics of simple structure, low density, light weight, thin thickness, low cost, flexibility, and can be designed conformally with curved surfaces, which has significant advantages in a wide range of application scenarios.

[0045] In a specific embodiment, a plurality of microwires are randomly filled in a paper-based material so that the distribution direction of the microwires is random; the size of the paper-based layer and the dielectric layer are both 200 mm*200 mm, the thickness of the dielectric layer is t=2 mm, and the microwire lengths of the above-mentioned absorbing structure are 8 mm, 6 mm, and 4 mm, respectively, and the microwire surface density is 2 g / m 2 , 4 g / m 2 , 6 g / m 2 , 8g / m 2 The simulation and experimental test were carried out under the condition of Figures 5 to 7 shown.

[0046] like Figure 5 As shown in the figure, when the microwire length is 8 mm, as the microwire surface density increases, the absorption band of the absorbing structure moves to low frequency; when the microwire surface density is 6 g / m 2 When the reflection coefficient is measured, it can reach up to -30 dB, corresponding to the frequency of 5.76 GHz.

[0047] like Figure 6 As shown in the figure, when the microwire length is 6 mm, as the microwire surface density increases, the absorbing frequency band of the absorbing structure moves to low frequency; when the microwire surface density is 6 g / m 2 When the reflection coefficient is 2.5×10, it can reach a maximum of -39.3 dB, corresponding to the frequency of 11.92 GHz. In general, the absorption bandwidth of the absorbing structure composed of 8 mm microwires is greatly improved, and the minimum can reach 3.84 GHz (microwire surface density 6 g / m 2 , absorption band 10.4~14.24 GHz) electromagnetic absorption, up to 6.8 GHz (microwire surface density 4 g / m 2, absorption band 11.2~18 GHz) electromagnetic absorption.

[0048] like Figure 7 As shown, when the microwire length is 4 mm, with the increase of the microwire surface density, the absorbing frequency band of the absorbing structure moves to low frequency, and the absorbing resonance point of the absorbing structure is larger than the tested frequency band.

[0049] Depend on Figures 5 to 7 It can be seen that when the length of the microwire is fixed, the absorption band of the absorbing structure moves to low frequency with the increase of the microwire surface density; when the microwire surface density is fixed, the absorption band of the absorbing structure also moves to low frequency with the increase of the microwire length. By changing the length and surface density of the microwire, the designable frequency band of the absorbing structure almost covers the C-Ku frequency band.

[0050] In another specific embodiment, a plurality of microwires are orderly filled in a paper-based material, so that the distribution direction of the microwires is orderly, and there are two distribution directions of the microwires, which are respectively parallel to a set of adjacent edges of the paper-based layer; the size of the paper-based layer and the dielectric layer are both 200 mm*200 mm, the thickness of the dielectric layer is t=2 mm, and the microwire length of the above-mentioned absorbing structure is 200 mm. Simulation and experimental tests are carried out under 5 microwire surface densities, and the results are as follows: Figure 8 and Fig. 9 shown.

[0051] like Figure 8 As shown in the figure, when the microwire length is 200 mm, as the microwire surface density increases, the absorption band moves to low frequency, and at the same time, the absorption of TE linear polarized electromagnetic waves is achieved.

[0052] like Fig. 9 As shown in the figure, when the microwire length is 200 mm, as the microwire surface density increases, the absorption band moves to low frequency, and at the same time, the absorption of TM linear polarized electromagnetic waves is achieved.

[0053] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

[0054] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0055] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A wave absorbing structure based on microfilament filled paper-based material, characterized in that: It includes stacked from top to bottom: a paper base layer and a medium layer; The paper base layer includes a plurality of microwires and a paper base material, the plurality of microwires are filled inside the paper base material, and the dielectric layer and the paper base layer are impedance matched; The length and / or surface density of the microwires are adjusted to adjust the working frequency band of the wave absorbing structure.

2. The microwave absorbing structure based on microwire-filled paper-based material according to claim 1, characterized in that: A plurality of the microwires are randomly filled in the paper-based material, so that the distribution direction of the microwires is random.

3. The microwave absorbing structure based on microwire-filled paper-based material according to claim 1, characterized in that: A plurality of the microwires are filled in the paper-based material in an orderly manner, so that the distribution direction of the microwires is orderly.

4. The microwave absorbing structure based on microwire-filled paper-based material according to claim 3, characterized in that: All microfilaments are distributed in the same direction.

5. The microwave absorbing structure based on microwire-filled paper-based material according to claim 4, characterized in that: The length directions of all microwires are parallel to a set of opposite sides of the paper substrate.

6. The microwave absorbing structure based on microwire-filled paper-based material according to claim 3, characterized in that: All the microwires have two distribution directions which are parallel to a set of adjacent edges of the paper base layer.

7. The microwave absorbing structure based on microwire-filled paper-based material according to any one of claims 1 to 6, characterized in that: The material of the microwire is glass-coated Co 72 Fe5Si8B 15 Amorphous alloy microwires.

8. The microwave absorbing structure based on microwire-filled paper-based material according to any one of claims 1 to 6, characterized in that: The material of the medium layer is PMI foam or air.

9. The microwave absorbing structure based on microwire-filled paper-based material according to any one of claims 1 to 6, characterized in that: Also includes: Floor layer; The floor layer is arranged on the lower surface of the medium layer to be connected with external equipment.

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