Wave-absorbing structure with configurable frequency band based on plane randomly-distributed microfilaments

Abstract

The invention belongs to the technical field of wave-absorbing structures, and relates to a frequency band configurable wave-absorbing structure based on plane random distribution microfilaments, which comprises more than two stacked wave-absorbing bodies, the wave absorbing body comprises a microfilament layer, a supporting layer and a substrate layer which are sequentially overlapped from top to bottom, the microfilament layer comprises a plurality of microfilaments which are randomly distributed in positions and directions, the supporting layer is of a plane structure and is used for supporting the microfilaments, and impedance matching is carried out on the substrate layer, the supporting layer and the microfilament layer; in the same wave absorber, the length and / or the surface density of the microfilaments are / is adjusted, so that the working frequency band of the wave absorber is adjusted on the premise that the thickness of the substrate layer is not changed; the lengths of the microfilaments of different wave absorbers are different, so that the frequency band can be configured; the lengths of the microfilaments of different wave absorbers are gradually increased from top to bottom; according to the invention, broadband / multiband electromagnetic absorption can be realized by configuring the corresponding single-layer structure.

Description

Technical Field

[0001] The present application relates to the technical field of wave absorbing structures, and in particular to a frequency band configurable wave absorbing structure based on planar randomly distributed microwires. 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 traditional absorbing coatings.

[0004] Metamaterial absorbers are generally designed by designing metal units of different shapes on a dielectric substrate, and utilizing the resonance effect of the metal units to absorb electromagnetic waves. Single-layer absorbing structures have a narrow absorbing bandwidth. To achieve multi-band or broadband electromagnetic absorption, it is often necessary to combine single-layer structures into multi-layer structures. However, there is an obvious electromagnetic coupling effect between multi-layer structures, resulting in mutual influence between layers. For example, structure A works in the A band, and structure B works in the B band. It is often difficult to achieve the superposition of the original two working bands by directly combining the two into a double-layer structure. In other words, to achieve simultaneous absorption of two frequency bands AB, it is not a simple matter of directly configuring two single-layer absorbing structures into a double-layer structure. The same is true for three-layer and more-layer structures. Therefore, the design process often relies on design experience, or relies on a large number of different structures for combination attempts. There is no clear method to guide the design, which is time-consuming, labor-intensive, and inefficient.

[0005] Traditional absorbing coatings include carbonyl iron powder, but they have problems such as narrow absorption band and high density, which limit their application. Moreover, the multi-layer combination design between different coatings also has strong electromagnetic coupling, and it is not a simple direct superposition of the working bands of single-layer absorbing structures.

[0006] In general, the existing single-layer absorbing structure has a narrow absorption band, and there is a strong electromagnetic coupling effect between the layers of the multi-layer absorbing structure, which is not a direct superposition of the single-layer absorbing bands. However, modern equipment has increasingly higher requirements for electromagnetic absorption, and has put forward the requirements for multi-band / wideband electromagnetic absorption, while the existing electromagnetic wave materials cannot meet the requirements of being configurable in the multi-layer design process to achieve the superposition of absorbing bands (for example, the existing structure A works in the A band, the structure B works in the B band, the structure C works in the C band, and the structure D works in the D band. To achieve simultaneous absorption of the three bands ACD, it is not enough to directly configure the three structures of ACD into a multi-layer structure. Similarly, to achieve simultaneous absorption of the three bands ABD / BCD, it is not enough to directly configure them into a multi-layer structure). Summary of the invention

[0007] Based on this, it is necessary to provide a band-configurable absorbing structure based on planar randomly distributed microwires to address the above-mentioned technical problems. The structure can directly combine and design single-layer structures working in the corresponding single band into multiple layers for the multi-band / broadband to be absorbed, and then realize broadband / multi-band electromagnetic absorption by configuring the corresponding single-layer structure. That is, the configurability of the absorbing band is achieved based on the weak coupling effect between the single-layer structures, which overcomes the technical problem in the prior art that direct combination cannot achieve broadband / multi-band electromagnetic absorption (it also needs to adjust the structure, size and matching).

[0008] A frequency band configurable wave absorbing structure based on planar randomly distributed microwires comprises: two or more stacked wave absorbing bodies; The wave absorbing body comprises: a microwire layer, a support layer and a substrate layer stacked in sequence from top to bottom; The microwire layer includes a plurality of microwires randomly distributed in positions and directions, the support layer is a planar structure for supporting the microwires, and the substrate layer performs impedance matching with the support layer and the microwire layer; In the same absorber, the length and / or surface density of the microwires are adjusted to adjust the working frequency band of the absorber without changing the thickness of the substrate layer; the lengths of the microwires of different absorbers are different to achieve configurable frequency bands.

[0009] In one embodiment, the lengths of the microwires of different absorbers increase from top to bottom.

[0010] In one embodiment, the support layers of different absorbers are completely identical.

[0011] In one embodiment, the substrate layers of different absorbers are completely identical.

[0012] In one embodiment, the material of the microwire layer is glass-coated Co 72 Fe5Si8B 15 Amorphous alloy microwires.

[0013] In one embodiment, the support layer is made of paper-based material or PET film.

[0014] In one embodiment, the material of the substrate layer is PMI foam or air.

[0015] In one embodiment, it further comprises: a bottom plate layer; The bottom plate layer is arranged on the lower surface of the lowest substrate layer to be connected with external equipment.

[0016] The above-mentioned frequency band configurable absorbing structure based on planar randomly distributed microwires is designed with microwire layers, support layers and substrate layers stacked in sequence. The microwires of different microwire layers have different microwire lengths and the same / different microwire surface densities, so that different absorbers work in different frequency bands. The multi-layer superposition design of more than two absorbers is conducive to the energy consumption of electromagnetic waves through interlayer reflection. At the same time, the microwires with random positions and directions can disrupt the strong peaks of incident electromagnetic wave scattering into irregular reflection waves, forming characteristics similar to diffuse reflection, thereby reducing the electromagnetic coupling between the multiple layers and achieving weak electromagnetic coupling between the multiple layers. Therefore, after the multi-layer superposition, the working frequency bands of the original single-layer structure can be combined to achieve broadband / multi-band impedance matching, and then achieve broadband / multi-band electromagnetic absorption. Therefore, according to the target absorption band, any single-layer structures can be directly combined to achieve band configurability; in contrast, in the prior art, due to the existence of strong coupling between layers, even if multiple single-layer structures are superimposed, the bandwidth of the multi-layer structure is not the superposition of each single-layer structure, and the band configurability cannot be achieved. The present application belongs to a composite material, and the electromagnetic coupling between the multilayer structures is weak, which solves the problem that the electromagnetic coupling between the multilayer structures in the prior art is strong and it is impossible to combine and configure any multiple single-layer structures according to the absorption band. In addition, the present application has a simple structure, low density, light weight, thin thickness, and low cost, and has significant advantages in a wide range of application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A three-dimensional diagram of a frequency band configurable absorbing structure based on planar randomly distributed microwires including two absorbing bodies in one embodiment; Figure 2 A side view of a frequency band configurable absorbing structure based on planar randomly distributed microwires in one embodiment includes two absorbing bodies; Figure 3 A three-dimensional diagram of a frequency band configurable absorbing structure based on planar randomly distributed microwires including three absorbing bodies in one embodiment; Figure 4 A side view of a frequency band configurable absorbing structure based on planar randomly distributed microwires including three absorbing bodies in one embodiment; Figure 5 In one embodiment, a band-configurable wave absorbing structure based on planar randomly distributed microwires includes two wave absorbing bodies, and the microwire surface density of the lower wave absorbing body is 2g / m 2 Reflection coefficient diagram of Figure 6 In one embodiment, a band-configurable wave absorbing structure based on planar randomly distributed microwires includes two wave absorbing bodies, and the microwire surface density of the lower wave absorbing body is 4g / m 2 Reflection coefficient diagram of Figure 7 In one embodiment, a band-configurable wave absorbing structure based on planar randomly distributed microwires includes two wave absorbing bodies, and the microwire surface density of the lower wave absorbing body is 6g / m 2 Reflection coefficient diagram of Figure 8 In one embodiment, a band-configurable absorbing structure based on planar randomly distributed microwires includes two absorbers, and the microwire surface density of the lower absorber is 8g / m 2 Reflection coefficient diagram of Fig. 9 A frequency band configurable absorbing structure based on planar randomly distributed microwires in one embodiment includes a reflection coefficient diagram of three absorbers; Fig.10 A band-configurable absorbing structure based on planar randomly distributed microwires includes a reflection coefficient diagram of four absorbers in one embodiment.

[0018] Reference numerals: Microwire layer 1, support layer 2, substrate layer 3, bottom plate layer 4. DETAILED DESCRIPTION

[0019] 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.

[0020] 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 in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] The present application provides a band-configurable wave absorbing structure based on planar randomly distributed microwires, such as Figures 1 to 4 As shown ( Figure 1 and Figure 2 It has two absorbers, forming a two-layer absorber structure, t1=t2; Figure 3 and Figure 4 There are three absorbing bodies to form a three-layer absorbing structure, t1=t2=t3), in one embodiment, including: more than two absorbing bodies, all of which are stacked in the vertical direction.

[0025] The wave absorbing body comprises: a microwire layer, a support layer and a substrate layer, wherein the microwire layer, the support layer and the substrate layer are stacked in sequence from top to bottom, and the support layer is equal in size to the substrate layer.

[0026] The microwire layer includes: multiple microwires, all microwires of the same absorber have the same length and surface density, and are randomly distributed on the upper surface of the support layer; it should be noted that the random here means that the distribution of the position and direction of the microwires is random, that is, the microwire layer includes multiple microwires with randomly distributed positions and directions.

[0027] The support layer is disposed on the upper surface of the substrate layer and is a planar structure for supporting the microwires. The support layer is made of a film material (specifically, a paper-based material or a PET film) and is flexible and conformal.

[0028] The impedance matching of the substrate layer, the support layer and the microwire layer is optimized. Specifically, impedance matching is achieved by changing the thickness of the substrate layer, the support layer and the microwire layer. For example, if the impedance of the support layer and the microwire layer is capacitive, the impedance of the substrate layer is designed to be inductive, thereby achieving impedance matching in a specific frequency band, so that electromagnetic waves can enter the material to the maximum extent and be lost instead of being reflected, thereby achieving efficient absorption of the incident electromagnetic waves. In addition, the substrate layer also serves as a base support.

[0029] In this embodiment, the lengths of the microwires of different absorbers are different, and the surface density of the microwires can be the same or different, so as to expand the absorbing frequency band, realize broadband / multi-band electromagnetic absorption, and further realize configurable frequency band. In the same absorber, the length and / or surface density of the microwires are adjusted to adjust the working frequency band of the absorber without changing the thickness of the substrate layer, so as to realize impedance matching in different frequency bands, thereby supporting flexible and simple design and regulation of the absorber within the broadband absorbing frequency band; specifically: the shorter the length of the microwire, the better the impedance matching at high frequency; the longer the length of the microwire, the better the impedance matching at low frequency; the smaller the surface density of the microwire, the better the impedance matching at high frequency; the larger the surface density of the microwire, the better the impedance matching at low frequency.

[0030] Preferably, the length of the microwires of different absorbers increases from top to bottom, so that the impedance matching of the absorber at low frequency becomes better and better along the direction from top to bottom, and the absorbing frequency band of the formed absorbing structure moves toward low frequency, thereby further expanding the absorbing frequency band and improving the absorbing bandwidth. Under the same surface density, the randomness of the microwires of the absorber from top to bottom becomes better and better.

[0031] Further preferably, the support layers of different absorbers are completely identical, and the substrate layers of different absorbers are completely identical, so that for a target frequency band, multi-band absorption can be achieved by combining and configuring a plurality of absorbers working in different frequency bands.

[0032] More preferably, when the absorber is double-layered, the surface densities of different absorbers are different, and when the absorber is three or more layers, the surface densities of different absorbers are the same, so as to further reduce the coupling effect.

[0033] In another embodiment, it also includes: a bottom plate layer; the bottom plate layer is arranged on the lower surface of the lowest substrate layer, and is made of metal material to be connected to external equipment; the external equipment can be equipment to be processed for electromagnetic compatibility or equipment to be processed for stealth, such as: the surface of an aircraft.

[0034] In the present application, the materials of the microwire layer, the support layer, the substrate layer and the bottom plate layer are all based on the prior art, which will not be described in detail. 72 Fe5Si8B 15 Amorphous alloy microwires, the material of the support layer is a film material (specifically, it can be a paper-based material or a PET film), the material of the substrate layer is PMI foam or air, and the bottom plate layer is copper.

[0035] The above-mentioned frequency band configurable absorbing structure based on planar randomly distributed microwires is designed with microwire layers, support layers and substrate layers stacked in sequence. The microwires of different microwire layers have different microwire lengths and the same / different microwire surface densities, so that different absorbers work in different frequency bands. The multi-layer superposition design of more than two absorbers is conducive to the energy consumption of electromagnetic waves through interlayer reflection. At the same time, the microwires with random positions and directions can disrupt the strong peaks of incident electromagnetic wave scattering into irregular reflection waves, forming characteristics similar to diffuse reflection, thereby reducing the electromagnetic coupling between the multiple layers and achieving weak electromagnetic coupling between the multiple layers. Therefore, after the multi-layer superposition, the working frequency bands of the original single-layer structure can be combined to achieve broadband / multi-band impedance matching, and then achieve broadband / multi-band electromagnetic absorption. Therefore, according to the target absorption band, any single-layer structures can be directly combined to achieve band configurability; in contrast, in the prior art, due to the existence of strong coupling between layers, even if multiple single-layer structures are superimposed, the bandwidth of the multi-layer structure is not the superposition of each single-layer structure, and the band configurability cannot be achieved. The present application belongs to a composite material, and the electromagnetic coupling between the multilayer structures is weak, which solves the problem that the electromagnetic coupling between the multilayer structures in the prior art is strong and it is impossible to combine and configure any multiple single-layer structures according to the absorption band. In addition, the present application has a simple structure, low density, light weight, thin thickness, and low cost, and has significant advantages in a wide range of application scenarios.

[0036] In a specific embodiment, the size of the support layer and the substrate layer are both 200 mm 200 mm, the number of absorbers were set to two, three and four respectively, and the reflection coefficient was tested experimentally respectively.

[0037] like Figures 5 to 8 As shown in the figure, the absorbing structure has two absorbers (an upper absorber and a lower absorber), the lengths of the microwires are 6 mm and 8 mm from top to bottom, the microwire surface density is the same / different, and the thickness of the substrate layer is 2 mm. It can be seen that the designed multiple double-layer structures all achieve dual-band electromagnetic absorption. Figure 6 For example, the upper layer is 6mm-4g / m 2 and lower layer 8mm-4g / m 2The frequency bands achieved by the design are: 5.68-8.56 GHz and 10.16-15.36 GHz, and the two frequency bands are the superposition of the original single-layer absorbing structure. Compared with the absorbing structure of the prior art, the electromagnetic coupling between the double-layer structures of the present application is weak, and dual-band electromagnetic absorption is effectively achieved; moreover, in order to achieve dual-band electromagnetic absorption, the two single-layer structures can be combined to achieve the configurability of the corresponding frequency bands (for example: to achieve A+B, A+C, A+D, B+C, B+D dual-band electromagnetic absorption, the corresponding combination of A+B, A+C, A+D, B+C, B+D structures can be achieved, and the same is true for other dual-band electromagnetic absorption).

[0038] like Fig. 9 As shown, the absorbing structure has three absorbing bodies. The lengths of the microwires are 5mm, 6mm, and 8mm from top to bottom, respectively, and the surface density of the microwires is 4g / m 2 , the thickness of the substrate layer is 2mm. It can be seen that the electromagnetic absorption of 5.76-18 GHz is achieved. Compared with the absorbing structure of two absorbers, in order to achieve the configurability of three bands, the three-layer structure is combined, and the electromagnetic absorption of three bands is achieved through weak electromagnetic coupling between the three layers. 2 , lower layer 8mm-4g / m 2 On the basis of the double-layer absorber composed of 5mm microwires with the same surface density, the uppermost layer is introduced to enhance the absorption of the high-frequency band on the basis of dual-band absorption, and the higher-frequency band is absorbed. The configuration of the frequency band is realized through the three-layer structure combination design. In order to achieve the target three-band electromagnetic absorption, the single-layer structure composed of three other lengths and surface densities of microwires can be combined to achieve the configuration of the corresponding frequency band (for example: to achieve electromagnetic absorption of the three bands of A+B+D, A+C+D, A+C+E, and A+D+E, the corresponding combination of A+B+D, A+C+D, A+C+E, and A+D+E can be achieved, and the same is true for other three-band electromagnetic absorption).

[0039] like Fig.10 As shown, the absorbing structure has four absorbing bodies, and the lengths of the microwires are 5mm, 7mm, 8mm, and 10mm from top to bottom, respectively, and the surface density of the microwires is 4g / m 2 , the thickness of the substrate layer is 2mm. It can be seen that the electromagnetic absorption of 3.76-18 GHz is achieved, and the absorption bandwidth is further increased compared with the absorption structure of three absorbers; moreover, on the basis of the three absorbers, by introducing 10mm microwires with the same surface density in the bottom layer, the absorption of the low frequency band is enhanced, and the electromagnetic absorption of the broadband is achieved.

[0040] Depend on Figures 5 to 10It can be seen that the electromagnetic coupling between the multi-layer absorber structures of the present application is weak. For specific target broadband / multi-band, it can be achieved by configuring the corresponding structure. For example, by combining a double-layer absorber, dual-band electromagnetic absorption can be achieved, by combining a three-layer absorber, triple-band electromagnetic absorption can be achieved, and by combining a four-layer absorber, broadband electromagnetic absorption can be achieved. In addition, the stacking of multiple absorbers expands the absorption bandwidth, and the introduction of short-filament layers with the same surface density can expand the high-frequency absorption bandwidth, and the introduction of long-filament layers with the same surface density can expand the low-frequency absorption bandwidth.

[0041] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

[0042] 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.

[0043] 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 band-configurable wave absorbing structure based on planar randomly distributed microwires, characterized in that: include: Two or more absorbers stacked together; The wave absorbing body comprises: a microwire layer, a support layer and a substrate layer stacked in sequence from top to bottom; The microwire layer includes a plurality of microwires randomly distributed in positions and directions, the support layer is a planar structure for supporting the microwires, and the substrate layer performs impedance matching with the support layer and the microwire layer; In the same absorber, the length and / or surface density of the microwires are adjusted to adjust the working frequency band of the absorber without changing the thickness of the substrate layer; the lengths of the microwires of different absorbers are different to achieve configurable frequency bands.

2. A frequency band configurable absorbing structure based on planar randomly distributed microwires according to claim 1, characterized in that: The length of the microfilaments of different absorbers increases from top to bottom.

3. The frequency band configurable absorbing structure based on planar randomly distributed microwires according to claim 2, characterized in that: The supporting layers of different absorbers are exactly the same.

4. The frequency band configurable absorbing structure based on planar randomly distributed microwires according to claim 3, characterized in that: The substrate layers of different absorbers are exactly the same.

5. A frequency band configurable absorbing structure based on planar randomly distributed microwires according to any one of claims 1 to 4, characterized in that: The material of the microwire layer is glass-coated Co 72 Fe5Si8B 15 Amorphous alloy microwires.

6. A frequency band configurable wave absorbing structure based on planar randomly distributed microwires according to any one of claims 1 to 4, characterized in that: The material of the support layer is paper-based material or PET film.

7. A frequency band configurable absorbing structure based on planar randomly distributed microwires according to any one of claims 1 to 4, characterized in that: The material of the substrate layer is PMI foam or air.

8. A frequency band configurable wave absorbing structure based on planar randomly distributed microwires according to any one of claims 1 to 4, characterized in that: Also includes: Bottom layer; The bottom plate layer is arranged on the lower surface of the lowest substrate layer to be connected with external equipment.

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