Broadband wave-absorbing periodic microstructure

Abstract

The utility model belongs to electromagnetic protection function structure material and application technical field, concretely relates to a kind of broadband wave-absorbing periodic microstructure, including first layer resonant unit, second layer magnetic material, third layer resonant unit, fourth layer magnetic material and fifth layer conductive backplate that are sequentially arranged from top to bottom;First layer resonant unit and third layer resonant unit are formed by hexagonal subunit, rectangular subunit, trapezoidal subunit and diamond subunit combination, and each subunit is periodically arrayed;The conductive backplate is fixedly connected with fourth layer magnetic material.The utility model is through the synergies of multilayer hexagonal, rectangular, trapezoidal and diamond combination array resonant unit, with magnetic wave-absorbing material, electromagnetic energy conversion of resonant unit and electromagnetic loss of magnetic material are mutually complementary, under 2-18GHz waveband, compared with pure magnetic wave-absorbing material, the absorption bandwidth of incident electromagnetic wave is significantly improved, bandwidth is improved from 0.89GHz to 15.62dB, bandwidth increases 14.73Hz.

Description

Technical Field

[0001] This utility model belongs to the field of electromagnetic protection functional structural materials and application technology, specifically relating to a broadband absorbing periodic microstructure. Background Technology

[0002] As military and civilian electronic information equipment, components, and parts develop towards higher power (high temperature resistance), miniaturization (thin film), integration, and resistance to harsh electromagnetic and space environments, electromagnetic interference (EMI) is increasingly becoming a key issue restricting the stable transmission of signals. High-performance electromagnetic shielding absorbing materials are becoming crucial raw materials for solving EMI problems in electronic information equipment and components. Periodic absorbing microstructures have become a research focus in high-performance electromagnetic shielding absorbing materials. However, while existing periodic absorbing microstructures have lower density than traditional absorbing materials, their absorption bandwidth is narrow, necessitating the development of broadband, high-efficiency, and lightweight absorbing materials. Utility Model Content

[0003] To address the technical problem of narrow absorption bandwidth in existing periodic microstructures, this invention provides a broadband periodic microstructure for absorbing microwaves.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows: A broadband absorbing periodic microstructure includes, from top to bottom, a first layer of resonant units, a second layer of magnetic material, a third layer of resonant units, a fourth layer of magnetic material, and a fifth layer of conductive backplate. The first and third resonant units are each formed by combining hexagonal, rectangular, trapezoidal, and rhombic sub-units, and these sub-units are arranged in a periodic array. The first, second, third, and fourth resonant units are integrally molded using injection molding, and the conductive backplate is fixedly connected to the fourth layer of magnetic material. By synchronously adjusting the dimensional parameters of the first and third resonant units, the thickness of the second and fourth magnetic materials, and their electromagnetic parameters, broadband absorption of electromagnetic waves in the 2-18 GHz band is achieved.

[0005] The size of each sub-unit of the third layer resonant unit is 1.05-1.2 times the size of the corresponding sub-unit of the first layer resonant unit, forming a size gradient distribution.

[0006] The second and fourth magnetic materials are composite materials of at least one of carbonyl iron, ferrite, and iron-silicon-aluminum with epoxy resin, wherein the mass ratio of magnetic powder is 60%-85% and the particle size of magnetic powder is 1-50μm.

[0007] The thickness of the first resonant unit is 0.2-0.5 mm, and the thickness of the third resonant unit is 0.1-0.3 mm; the thickness of the second magnetic material is 0.8-1.5 mm, and the thickness of the fourth magnetic material is 0.1-0.3 mm, and the thickness ratio of the second magnetic material to the fourth magnetic material is 3:1-8:1.

[0008] The periodic array spacing of each sub-unit in the first and third resonant units is 8-12mm, and the ratio of this spacing to the electromagnetic wave wavelength corresponding to the center frequency of the 2-18GHz band is 1:5-1:20.

[0009] The edges of the hexagonal sub-units, rectangular sub-units, trapezoidal sub-units and rhomboid sub-units included in the first layer resonant unit and the third layer resonant unit are all chamfered, with a chamfer radius of 0.1-0.3mm.

[0010] The fifth conductive backplate is a copper foil, aluminum foil, or conductive silver paste layer with a thickness of 0.01-0.03 mm, and the sheet resistance of the conductive backplate is ≤0.1Ω / □.

[0011] In the first layer of resonant units, the aspect ratio of the rectangular sub-units is 1.2-1.5, the ratio of the long side to the short side of the trapezoidal sub-units is 1.3-1.6, and the ratio of the side length of the hexagonal sub-units to the side length of the rhombus sub-units is 0.6-0.8.

[0012] The sub-unit arrays of the first layer of resonant units and the sub-unit arrays of the third layer of resonant units are arranged in a staggered manner, with a stagger distance of 1 / 4 to 1 / 2 of the spacing between the sub-unit arrays.

[0013] The dielectric constant εr of the second and fourth magnetic materials are both 3-8, the permeability μr is both 2-6, and the loss tangent is ≥0.3 in the 2-18 GHz band.

[0014] Compared with the prior art, the advantages of this utility model are: This invention focuses on a combined array of hexagonal, rectangular, trapezoidal, and rhombic periodic microstructures for absorbing electromagnetic waves. By designing and arranging the combined array microstructures, it enhances the coplanar and non-coplanar coupling effects between units to extend the bandwidth, resulting in a periodic microstructure unit with a broadened absorption frequency band. This differs from the single resonant mode of planar periodic absorbing structures and solves the problem of narrow absorption bandwidth in traditional periodic microstructures, thereby reducing electromagnetic radiation interference to equipment and systems. Through the synergistic effect of multi-layered hexagonal, rectangular, trapezoidal, and rhombic combined array resonant units and magnetic absorbing materials, the electromagnetic energy conversion of the resonant units and the electromagnetic loss of the magnetic materials complement each other. In the 2-18 GHz band, the absorption bandwidth of incident electromagnetic waves is significantly improved compared to simple magnetic absorbing materials, increasing from 0.89 GHz to 15.62 dB, an increase of 14.73 Hz. Attached Figure Description

[0015] To more clearly illustrate the embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0016] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the implementation conditions of this utility model. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationships, or adjustments to the size, without affecting the effects and purposes that this utility model can produce, should still fall within the scope of the technical content disclosed in this utility model.

[0017] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 These are simulation comparison images of this utility model.

[0018] Wherein: 1 is the first layer of resonant unit, 2 is the second layer of magnetic material, 3 is the third layer of resonant unit, 4 is the fourth layer of magnetic material, and 5 is the fifth layer of conductive backplate. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions in the embodiments of this utility model will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. These descriptions are only for further illustrating the features and advantages of this utility model, and not for limiting the claims of this utility model. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] The specific embodiments of this utility model will be further described in detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this utility model, but are not intended to limit the scope of this utility model.

[0021] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0022] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0023] Example 1: Basic broadband absorbing periodic microstructure This embodiment is a 5-layer composite structure, such as Figure 1As shown, from top to bottom, the layers are: first resonant unit 1, second magnetic material 2, third resonant unit 3, fourth magnetic material 4, and fifth conductive backplate 5. The first layer of resonant units 1 consists of a periodic array of rectangular, trapezoidal, hexagonal, and rhomboid sub-units, with a spacing P = 10 mm. The dimensions of each sub-unit are as follows: rectangle: length 5.8 mm, width 4.7 mm (length-to-diameter ratio 1.23); trapezoid: short side 4.5 mm, long side 6.3 mm (long side to short side ratio 1.4); hexagon: side length 3.8 mm; rhomboid: side length 5.4 mm (side length ratio 0.7). All sub-units have a 0.2 mm chamfer at the edges, and the unit thickness is 0.4 mm. The third layer of resonant units 3 has the same sub-unit type as the first layer, but the size is 1.1 times that of the first layer. The array is staggered from the first layer by a distance of 3.3 mm (1 / 3 of the spacing), and the thickness is 0.3 mm. The second layer of magnetic material 2 has a thickness of 1.0 mm, and the fourth layer of magnetic material 4 has a thickness of 0.2 mm (thickness ratio 5:1). The fifth layer of conductive backplate 5 is a 0.018 mm thick copper foil with a sheet resistance ≤ 0.1 Ω / □.

[0024] The first layer resonant unit 1, the third layer resonant unit 3, the second layer magnetic material 2, and the fourth layer magnetic material 4 are all made of carbonyl iron powder and epoxy resin composite material. The carbonyl iron powder has a particle size of 5-20μm and accounts for 75% of the mass, while the epoxy resin accounts for 25%. The material has a dielectric constant εr=5.2, a permeability μr=4.1, and a loss tangent of 0.35 in the 2-18GHz band. The fifth layer conductive backplate 5 is made of 99.9% pure electrolytic copper foil, and the surface is passivated to improve oxidation resistance.

[0025] Two sets of injection molds with chamfered structures are processed according to the above dimensions. Carbonyl iron powder is mixed with epoxy resin and 0.5% by mass of curing agent is added. The mixture is stirred at 800 r / min for 30 min to form a uniform slurry. The slurry is first injected into the mold of the first layer resonant unit, and injection molded at 170℃ and 6MPa pressure and kept at the temperature for 30 min to cure, thus obtaining the first layer resonant unit 1. Then, a magnetic slurry is coated on its surface with a thickness of 1.0 mm and cured at 170℃ for 20 min to form the second layer magnetic material 2. Next, the third layer resonant unit 3 is injected into the surface of the second layer magnetic material 2 at the misaligned position of the first layer (process is the same as the first layer). Then, a magnetic slurry is coated on the surface with a thickness of 0.2 mm and cured to form the fourth layer magnetic material 4. Finally, a 5μm thick conductive adhesive is coated on the surface of the fourth layer magnetic material 4, and copper foil is attached and fixed with a pressure of 2MPa and a temperature of 80℃ for 15 min to complete the five-layer integral molding. Tested using a vector network analyzer according to GB / T25076-2010 standard, the effective absorption bandwidth with a reflectivity ≤ -10dB in the 2-18GHz band is 15.62GHz (covering 2.38-18GHz), and the overall material density is 3.2g / cm³. 3The maximum absorption peak is -28.5dB (at 8.7GHz).

[0026] Example 2: Parameter Optimization Example The broadband absorbing periodic microstructure in this embodiment is still a five-layer structure. The first layer resonant unit 1 has a rectangular sub-unit with a length of 6.0 mm and a width of 4.28 mm (length-to-diameter ratio 1.4), a trapezoidal sub-unit with a short side of 4.0 mm and a long side of 6.0 mm (long side to short side ratio 1.5), a hexagonal sub-unit with a side length of 4.0 mm, and a rhombic sub-unit with a side length of 5.0 mm (side length ratio 0.8). The array spacing P = 9 mm, and the unit thickness is 0.35 mm. The third layer resonant unit 3 is 1.08 times the size of the first layer, and the array is offset from the first layer by 2.25 mm (1 / 4 of the spacing), with a thickness of 0.25 mm. The second layer magnetic material 2 has a thickness of 1.2 mm, and the fourth layer magnetic material 4 has a thickness of 0.24 mm (thickness ratio 5:1). The conductive backplate 5 is a 0.02 mm thick aluminum foil with a sheet resistance ≤ 0.15 Ω / □.

[0027] Both the resonant unit and the magnetic material are made of Ni-Zn ferrite powder and epoxy resin composite material. The ferrite powder has a particle size of 10-30μm and accounts for 80% of the mass, while the epoxy resin accounts for 20%. The material has a dielectric constant εr=6.5, a permeability μr=5.2, and a loss tangent of 0.4 in the 2-18GHz band. The fifth conductive backplate 5 is made of aluminum foil with a purity of 99.5% and the surface is anodized.

[0028] The manufacturing process follows the injection molding method of Example 1, with the only adjustments being made to the curing temperature (160℃) and curing time (extended to 25 min) based on the properties of the ferrite material. Performance testing results show that the effective absorption bandwidth (covering 2.8-18 GHz) with a reflectivity ≤ -10 dB in the 2-18 GHz band is 15.2 GHz, and the overall material density is 3.5 g / cm³. 3 Furthermore, its reflectivity remains stable at ≤-15dB in the 12-15GHz high-frequency band, meeting the high-frequency protection requirements of radar systems.

[0029] Example 3: Comparative Example (Traditional Flat Panel Structure) This embodiment is a traditional single-layer flat plate structure, consisting only of a flat magnetic absorbing material and a flat conductive backplate, without multi-layer resonant units, size gradients, or staggered arrangements. The flat magnetic absorbing material has the same composition as the magnetic material in Embodiment 1, a thickness of 6.0 mm, and a unit size P = 10 mm. The flat conductive backplate is the same as the conductive backplate 5 in Embodiment 1, consisting of 0.018 mm thick copper foil with a sheet resistance ≤ 0.1 Ω / □.

[0030] The flat magnetic absorbing material 1 is prepared by molding process: the magnetic slurry of Example 1 is poured into the flat mold and molded at 170°C and 8MPa pressure. After curing at 30 minutes, the flat conductive backplate is directly bonded to its surface (bonding process is the same as in Example 1), without going through the resonant unit injection molding and multi-layer composite steps.

[0031] Performance testing was conducted according to the testing standards of Example 1, such as... Figure 2 As shown, the absorption bandwidth of the multilayer combined array periodic microstructure absorbing material (1#) in Example 1 is significantly improved compared with the absorption bandwidth of the planar magnetic absorbing material (2#) in Example 3, with the bandwidth increasing from 0.89GHz to 15.62dB, and the density of magnetic absorbing material in the composite structure is reduced.

[0032] The above description only describes the preferred embodiments of the present utility model. However, the present utility model is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present utility model, and all such changes should be included within the protection scope of the present utility model.

Claims

1. A broadband absorbing periodic microstructure, characterized in that: The system includes a first layer of resonant unit (1), a second layer of magnetic material (2), a third layer of resonant unit (3), a fourth layer of magnetic material (4), and a fifth layer of conductive backplate (5) arranged sequentially from top to bottom. The first layer of resonant unit (1) and the third layer of resonant unit (3) are both formed by combining hexagonal sub-units, rectangular sub-units, trapezoidal sub-units, and rhombic sub-units, and each sub-unit is arranged in a periodic array. The first layer of resonant unit (1), the second layer of magnetic material (2), the third layer of resonant unit (3), and the fourth layer of magnetic material (4) are integrally formed by injection molding. The conductive backplate (5) is fixedly connected to the fourth layer of magnetic material (4). By synchronously adjusting the size parameters of the first layer of resonant unit (1) and the third layer of resonant unit (3), the thickness of the second layer of magnetic material (2) and the fourth layer of magnetic material (4), and the electromagnetic parameters, broadband absorption of electromagnetic waves in the 2-18GHz band is achieved.

2. The broadband absorbing periodic microstructure according to claim 1, characterized in that: The size of each sub-unit of the third layer resonant unit (3) is 1.05-1.2 times the size of the corresponding sub-unit of the first layer resonant unit (1), forming a size gradient distribution.

3. The broadband absorbing periodic microstructure according to claim 1, characterized in that: The thickness of the first layer resonant unit (1) is 0.2-0.5 mm, the thickness of the third layer resonant unit (3) is 0.1-0.3 mm, the thickness of the second layer magnetic material (2) is 0.8-1.5 mm, the thickness of the fourth layer magnetic material (4) is 0.1-0.3 mm, and the thickness ratio of the second layer magnetic material (2) to the fourth layer magnetic material (4) is 3:1-8:

1.

4. The broadband absorbing periodic microstructure according to claim 1, characterized in that: The periodic array spacing of each sub-unit in the first layer resonant unit (1) and the third layer resonant unit (3) is 8-12mm, and the ratio of this spacing to the electromagnetic wave wavelength corresponding to the center frequency of the 2-18GHz band is 1:5-1:

20.

5. The broadband absorbing periodic microstructure according to claim 1, characterized in that: The edges of the hexagonal sub-units, rectangular sub-units, trapezoidal sub-units and rhomboid sub-units included in the first layer resonant unit (1) and the third layer resonant unit (3) are all chamfered with a chamfer radius of 0.1-0.3mm.

6. The broadband absorbing periodic microstructure according to claim 1, characterized in that: The fifth conductive backplate (5) is a copper foil, aluminum foil or conductive silver paste layer with a thickness of 0.01-0.03 mm, and the sheet resistance of the conductive backplate (5) is ≤0.1Ω / □.

7. The broadband absorbing periodic microstructure according to claim 1, characterized in that: In the first layer of resonant unit (1), the aspect ratio of the rectangular sub-unit is 1.2-1.5, the ratio of the long side to the short side of the trapezoidal sub-unit is 1.3-1.6, and the ratio of the side length of the hexagonal sub-unit to the side length of the rhombus sub-unit is 0.6-0.

8.

8. The broadband absorbing periodic microstructure according to claim 1, characterized in that: The sub-unit array of the first layer resonant unit (1) and the sub-unit array of the third layer resonant unit (3) are arranged in a staggered manner, with a stagger distance of 1 / 4 to 1 / 2 of the sub-unit array spacing.

9. The broadband absorbing periodic microstructure according to claim 1, characterized in that: The dielectric constant εr of the second layer magnetic material (2) and the magnetic permeability μr of the fourth layer magnetic material (4) are both 3-8 and 2-6, respectively, and the loss tangent value in the 2-18GHz band is ≥0.3.

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