Lightweight high-mechanical-strength electromagnetic wave-transparent composite material, preparation method and application thereof

Abstract

The present application relates to the technical field of electromagnetic metamaterials, and aims at the defects of large weight, insufficient mechanical strength, large electromagnetic performance loss, complex preparation process, low forming precision and the like caused by the split design of the existing electromagnetic wave-transparent composite material, and provides a light-weight high-mechanical-strength electromagnetic wave-transparent composite material, a preparation method and application thereof.The electromagnetic wave-transparent composite material is formed by integrating self-pressing and laser technology, and a plurality of basic units are arranged in a two-dimensional periodic array.The five-layer symmetrical composite structure includes a honeycomb structure layer in the middle, and metal structure layers and dielectric layers symmetrically distributed on both sides of the honeycomb structure layer.The present application has the advantages of light weight, high mechanical strength, excellent electromagnetic wave-transparent function, and can meet the electromagnetic wave-transmission requirements of multi-polarization and wide incidence angle scenarios.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic metamaterials technology, and in particular to a lightweight, high-mechanical-strength electromagnetically transparent composite material, its preparation method, and its application. Background Technology

[0002] Electromagnetic wave-transparent composite materials are a class of materials that allow electromagnetic waves to pass through with low loss and high efficiency, while also possessing specific structural load-bearing or environmental protection functions. They are used to achieve the function of efficient electromagnetic wave transmission and are widely used in scenarios where internal electronic equipment needs to be protected but signal transmission cannot be blocked, such as radomes, electromagnetic transparent windows, and other components in radar, communication, aerospace, and other fields.

[0003] Traditional electromagnetically transparent composite materials often adopt a split design of "functional layer + load-bearing layer". The functional layer only achieves the electromagnetic anti-reflection effect and needs to be paired with an additional load-bearing structure to meet the mechanical strength requirements. This results in a large overall structure with high weight, and the interlayer bonding is prone to introducing interface loss, which reduces electromagnetic performance. At the same time, traditional manufacturing processes often use methods such as photolithography and etching to prepare metal structures, which are then assembled with dielectric structures. The process is complex and has low forming accuracy, making it difficult to achieve integrated preparation of complex microstructures. Furthermore, the angular stability and frequency band adaptability of the structure are significantly limited by the manufacturing process.

[0004] In existing technologies, some wave-transparent structures are attempting to balance the dual requirements of lightweight and mechanical strength. However, these are currently mostly achieved through simplified structural designs, leading to a decrease in electromagnetic wave transmission performance. High-performance electromagnetic wave-transparent composite materials, on the other hand, often suffer from complex structures, heavy weight, and insufficient mechanical strength, failing to meet the dual demands of aerospace, automotive, and mobile communication fields for integrated structural functions, lightweight construction, and high mechanical strength. Furthermore, the mismatch between the dielectric properties of traditional dielectric materials and metal structures easily leads to electromagnetic wave reflection and loss, further reducing the anti-reflection effect.

[0005] Therefore, developing an electromagnetic wave-transmitting composite material that combines lightweight and high mechanical strength through integrated manufacturing technology has become an urgent technical problem to be solved in this field. Summary of the Invention

[0006] To address the shortcomings of existing electromagnetic wave-transparent composite materials, such as heavy weight, insufficient mechanical strength, high electromagnetic performance loss due to their split design, complex manufacturing process, and low molding precision, this invention aims to provide a lightweight, high-mechanical-strength electromagnetic wave-transparent composite material, its preparation method, and its applications. This electromagnetic wave-transparent composite material adopts a functionally integrated design with a five-layer symmetrical composite structure. It utilizes 3D printing technology to achieve integrated molding of the medium and metal structure, combining the structural advantages of lightweight and high mechanical strength with excellent electromagnetic wave transmission function. This effectively solves the technical problems of "separation of structure and function," "contradiction between lightweight and high mechanical strength," and "complex manufacturing process" in traditional structures.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention discloses a lightweight, high mechanical strength electromagnetic wave-transparent composite material. The electromagnetic wave-transparent composite material is formed by arranging multiple basic units in a two-dimensional periodic array and integrally molding them using self-pressing and laser technology. Each basic unit is a five-layer symmetrical composite structure. The five-layer symmetrical composite structure includes a honeycomb structure layer located in the middle, and a metal structure layer and a dielectric layer symmetrically distributed on both sides of the honeycomb structure layer. The honeycomb structure layer and the dielectric layer are both made of high-frequency dielectric material with a dielectric constant of 3.28 and a loss tangent of 0.002. The metal structure layer is made of copper.

[0009] As a further preferred embodiment, the honeycomb structure layer has a rectangular plate-shaped porous structure, and several rows of parallel cylindrical through holes are provided through the honeycomb structure layer along the thickness direction. Adjacent cylindrical through holes are interconnected by arc-shaped grooves, so that the connection area between adjacent cylindrical through holes has an inwardly concave curved surface shape.

[0010] A further preferred technical solution is that the cylindrical through-holes located at the edge of the honeycomb structure layer also have inwardly recessed arc-shaped openings on their outer sides, so that a continuous pore network is formed as a whole.

[0011] A further preferred technical solution is that the length of the honeycomb structure layer is... ,width Thickness hm=6.3mm.

[0012] As a further preferred embodiment, the axis of each cylindrical through-hole is parallel to the thickness direction of the honeycomb structure layer, and the radius of the cylindrical through-hole is rk=1.7mm, and its thickness is the same as that of the honeycomb structure layer.

[0013] As a further preferred solution, the metal structural layer comprises an annular metal hollow grid and a circular metal sheet, the circular metal sheet is coaxially arranged at the center of the annular metal hollow grid, the thickness of the metal structural layer is 0.017mm, and the length and width thereof are both the same as those of the honeycomb structural layer.

[0014] Further, the outer diameter rout of the central ring of the annular metal hollow grid is 3.13mm, and the inner diameter rin thereof is 2.88mm.

[0015] A further preferred technical solution is that herringbone-shaped arcs and two quarter-circular metal sheets are symmetrically arranged at the upper and lower ends of the central ring, the herringbone-shaped arcs are externally tangent to the central ring, each quarter-circular metal sheet is arranged concentrically with each segment of the herringbone-shaped arcs, and the radius r1 of the circular metal sheet is 2mm.

[0016] In a second aspect, the present invention discloses a method for preparing a lightweight electromagnetic wave-transparent composite material with high mechanical strength, comprising the following steps:

[0017] Step 1: Laying a high-frequency dielectric material, and pressing the material to a thickness of 0.5mm through a self-pressing process to obtain a dielectric layer;

[0018] Step 2: Laying a metal copper sheet on one side of the dielectric layer, and etching a designed structure by a laser process to obtain a metal structural layer;

[0019] Step 3: Continuously laying a high-frequency dielectric material on the side of the metal structural layer away from the dielectric layer until the laid thickness reaches 6.3mm, so as to obtain a 6.3mm thick dielectric plate, and a plurality of rows of parallel-distributed cylindrical through holes are excavated on the dielectric plate according to the designed structure by a laser process to obtain a honeycomb structural layer.

[0020] Step 4: Sequentially laying a metal copper sheet and a high-frequency dielectric material on the side of the honeycomb structural layer away from the dielectric layer, so as to form a symmetrical metal structural layer and a symmetrical dielectric layer on the other side of the honeycomb structural layer, and adding a prepreg between each layer of the dielectric layer, the metal structural layer and the honeycomb structural layer to realize connection between the layers.

[0021] In a third aspect, the present invention discloses the application of the lightweight electromagnetic wave-transparent composite material with high mechanical strength in radomes, millimeter wave communication infrastructures, stealth equipment and electromagnetic windows.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. This invention abandons the traditional split design of "functional layer + load-bearing layer" and adopts a five-layer symmetrical composite structure. The honeycomb structure layer and the dielectric layer realize the lightweight and high mechanical strength load-bearing function of the structure, and the metal structure layer realizes the electromagnetic function of electromagnetic wave anti-transmission. One-time molding can meet the dual requirements of structure and electromagnetic wave transmission, greatly simplifying the subsequent assembly process.

[0024] 2. The central cylinder of the honeycomb structure layer of this invention adopts a hollow design, which greatly reduces the weight of the overall structure and achieves lightweighting; the five-layer symmetrical composite structure is integrally formed by self-pressing and laser technology to ensure the connection strength between each layer structure. Combining the mechanical properties of dielectric materials and metallic copper, the overall electromagnetic wave-transparent composite material has excellent compressive and flexural mechanical strength, achieving a unity of lightweight and high mechanical strength, and meeting the usage requirements of harsh working conditions.

[0025] 3. The metal structure layer of this invention adopts a coaxial composite design of a circular annular metal mesh and circular metal sheets. The central annular metal mesh has symmetrically arranged "V"-shaped arcs and two quarter-circular metal sheets at its upper and lower ends. The "V"-shaped arcs are externally tangent to the central annular ring, and each quarter-circular metal sheet is concentrically positioned with each segment of the "V"-shaped arc. Based on this special design of the circular annular metal mesh and circular metal sheets, combined with a low-loss dielectric material with a dielectric constant of 3.28 and a loss tangent of 0.002, the equivalent electromagnetic parameters can be precisely controlled, achieving efficient transmission of electromagnetic waves in the target frequency band. Simulation tests show that this electromagnetic wave-transmitting composite material exhibits high transmission coefficients for TE and TM waves in the 12.3–16.4 GHz frequency band. All are better than -0.6 dB in the 13–16 GHz core band. It is further superior to -0.3 dB, and has balanced dual-polarization performance and excellent angular stability, which can meet the electromagnetic anti-reflection requirements of multi-polarization and wide incident angle scenarios.

[0026] 4. This invention achieves integrated molding of the honeycomb structure layer, dielectric layer and metal structure layer through self-pressing and laser technology, which can accurately prepare complex circular annular metal hollow mesh microstructures with high molding precision. Compared with traditional photolithography, etching and assembly processes, it greatly simplifies the preparation process, reduces production costs, and avoids the problems of electromagnetic loss and mechanical strength reduction caused by interlayer bonding gaps.

[0027] 5. This invention selects a low-loss dielectric material with a dielectric constant of 3.28 and a loss tangent of 0.002 and combines it with high-conductivity metallic copper. The electromagnetic properties of the dielectric and the metal are well matched, which further enhances the electromagnetic wave transmission reduction effect. At the same time, both materials are compatible with self-pressurization and laser technology processes, ensuring the feasibility of integrated molding. Attached Figure Description

[0028] To more clearly illustrate the embodiments and design schemes of the present invention, the accompanying drawings required for this embodiment will be briefly described below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 is a schematic diagram of the overall layered structure of a lightweight, high mechanical strength electromagnetic wave-transmitting composite material provided by the present invention.

[0030] Figure 2 is a schematic diagram of the 4×4 structure of the electromagnetic wave-transmitting composite material provided by the present invention.

[0031] Figure 3 is a schematic diagram of the unit structure of the electromagnetic wave-transmitting composite material provided by the present invention;

[0032] Figure 4 is a schematic diagram of the planar structure of the honeycomb structure layer provided by the present invention.

[0033] Figure 5 is a schematic diagram of the planar structure of the metal structural layer provided by the present invention.

[0034] Figure 6 shows the S-parameters of the electromagnetic wave-transmitting composite material in Example 1 of the present invention. Simulation results diagram.

[0035] Figure 7 shows the S-parameters of the electromagnetic wave-transmitting composite material and the pure dielectric layer in Embodiment 1 of the present invention. Simulation results diagram.

[0036] In the diagram: 1. Honeycomb structure layer; 11. Cylindrical through-hole; 2. Metal structure layer; 21. Circular metal mesh; 22. Circular metal sheet; 23. Central ring; 24. "A" shaped arc; 25. 1 / 4 circular metal sheet; 3. Dielectric layer. Detailed Implementation

[0037] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0038] Example 1:

[0039] Reference Figure 1, the present invention provides a lightweight electromagnetic wave-transparent composite material with high mechanical strength. The electromagnetic wave-transparent composite material is formed by arranging a plurality of basic units in a two-dimensional periodic array and integrally molding through self-pressing and laser technology. Each basic unit is a five-layer symmetrical composite structure, which includes a honeycomb structure layer 1 located in the middle, and a metal structure layer 2 and a dielectric layer 3 symmetrically distributed on both sides of the honeycomb structure layer 1 in sequence. Both the honeycomb structure layer 1 and the dielectric layer 3 are made of a high-frequency dielectric material with a dielectric constant of 3.28 and a loss tangent of 0.002, and the metal structure layer 2 is made of metallic copper.

[0040] Specifically, as shown in Figures 2-4 , the honeycomb structure layer 1 has a rectangular plate-shaped porous structure. A plurality of rows of parallel distributed cylindrical through holes 11 are penetratingly arranged in the honeycomb structure layer 1 along the thickness direction, and adjacent cylindrical through holes 11 are communicated with each other through arc-shaped grooves, so that the connection region between adjacent cylindrical through holes 11 presents an inwardly recessed curved surface shape, and the outer side of the cylindrical through hole 11 located at the edge of the honeycomb structure layer 1 is also provided with an inwardly recessed arc-shaped opening, forming a continuous pore network as a whole. Preferably, the length of the honeycomb structure layer 1 , the width , and the thickness hm=6.3mm. The axis of each cylindrical through hole 11 is parallel to the thickness direction of the honeycomb structure layer 1, the radius rk of the cylindrical through hole 11 is 1.7mm, and its thickness is consistent with that of the honeycomb structure layer 1, that is, the thickness of the cylindrical through hole 11 is hm=6.3mm.

[0041] The central hollow design of the honeycomb structure layer 1 reduces the structural weight by more than 30%, while the mechanical properties of the honeycomb structure ensure that the compressive strength of the structure is ≥50MPa and the flexural strength is ≥20MPa, realizing the unification of lightweight and high mechanical strength.

[0042] As shown in Figure 5 , the metal structure layer 2 includes an annular metal hollow grid 21 and a circular metal sheet 22. The circular metal sheet 22 is coaxially arranged at the center of the annular metal hollow grid 21. The thickness of the metal structure layer 2 is 0.017mm, its length and width are the same as those of the honeycomb structure layer 1, and the radius r1 of the circular metal sheet 22 is 2mm. Preferably, the outer diameter rout of the central ring 23 of the annular metal hollow grid 21 is 3.13mm, and its inner diameter rin is 2.88mm.

[0043] In some preferred embodiments, the upper and lower ends of the central ring 23 are symmetrically provided with a herringbone-shaped arc 24 and two quarter-circular metal sheets 25. The herringbone-shaped arc 24 is externally tangent to the central ring 23, and each quarter-circular metal sheet 25 is arranged concentrically with each arc segment of the herringbone-shaped arc 24.

[0044] The coaxial design of the metal structure layer 2 enables the five-layer symmetrical composite structure to have an electromagnetic wave transmittance of ≥93% in the microwave frequency band of 12.3–16.4 GHz, exhibiting excellent electromagnetic wave transmission performance.

[0045] In some preferred embodiments, the dielectric layer 3 has a cubic structure with a length py = ×r=6.06mm, width px=3×r=10.5mm, thickness hn=0.5mm, the two dielectric layers 3 are symmetrically arranged on both sides of the honeycomb structure layer 1, providing mechanical protection and low-loss electromagnetic transmission channels for the overall five-layer symmetrical composite structure.

[0046] In this embodiment, both the honeycomb structure layer 1 and the dielectric layer 3 are made of low-loss dielectric materials with a dielectric constant of 3.28 and a loss tangent of 0.002, and the metal structure layer 2 has a conductivity of 5.8 × 10⁻⁶. The S / m metallic copper material and the five-layer symmetrical composite structure ensure high mechanical strength. The hollow design of the honeycomb structure layer 1 achieves lightweighting. The combination design of the circular metal hollow mesh 21 and the circular metal sheet 22 in the metal structure layer 2 achieves excellent electromagnetic wave transmission enhancement effect. The structure adopts an integrated design, which combines lightweight, high mechanical strength and electromagnetic wave transmission characteristics.

[0047] Example 2:

[0048] This invention also provides a method for preparing a lightweight, high-mechanical-strength electromagnetic wave-transmitting composite material, employing a step-by-step molding process of "dielectric first, then metal," including the following steps:

[0049] Step 1: Lay high-frequency dielectric material and press it to a thickness of 0.5mm using a self-pressing process to obtain dielectric layer 3;

[0050] Step 2: Lay a copper sheet on one side of the dielectric layer 3, and use laser technology to etch out the designed structure to obtain the metal structure layer 2;

[0051] Step 3: Continue to lay high-frequency dielectric material on the side of the metal structure layer 2 away from the dielectric layer 3 until the thickness reaches 6.3mm, to obtain a 6.3mm thick dielectric board. Using laser technology, several rows of parallel cylindrical through holes 21 are drilled on the dielectric board according to the design structure to obtain the honeycomb structure layer 1.

[0052] Step 4: Lay copper sheets and high-frequency dielectric material sequentially on the side of the honeycomb structure layer 1 away from the dielectric layer 3. Form a symmetrical metal structure layer 2 and dielectric layer 3 on the other side of the honeycomb structure layer 1. Add a prepreg between each layer of the dielectric layer 3, metal structure layer 2, and honeycomb structure layer 1 to connect the layers.

[0053] like Figures 6-7As shown, the electromagnetic wave-transparent composite material of the present invention was subjected to S-parameter simulation comparison tests with a pure dielectric plate of the same thickness under 60° large-angle incident and TE polarization conditions. The results show that the pure dielectric plate has higher S-parameter performance in the 11.2–13.5 GHz frequency band. It slowly rises to a peak of -0.2 dB, then drops rapidly after 13.5 GHz, reaching a low of 15 GHz. The transmittance drops to -2 dB, and further to below -3 dB after 16 GHz, with a sharp deterioration in high-frequency transmission performance under large-angle incident conditions. However, the electromagnetic transmittance composite material of this invention maintains its performance across the entire frequency band from 12 to 17 GHz. All are better than -0.5 dB in the 13–16 GHz core band. It stabilized at around -0.3 dB, with peak transmittance occurring near 13.5 GHz and 15.5 GHz. The impedance is approximately -0.2dB, maintaining excellent broadband wave transmission performance even under large-angle incident conditions. The comparative results fully verify the wave transmission advantages of the electromagnetic wave-transmitting composite material of this invention under 60° large-angle incident and TE polarization conditions, which can effectively meet the electromagnetic window requirements of large-angle incident scenarios such as aerospace and automotive radar.

[0054] In summary, the lightweight, high-mechanical-strength electromagnetic wave-transparent composite material provided by this invention achieves a synergistic balance between lightweight structure and high mechanical strength through a functionally integrated five-layer symmetrical composite structure design, combined with 3D printing integrated fabrication technology and precise electromagnetic parameter control. This solves the transmission loss problem under wide-band dual-polarized electromagnetic wave incidence, resulting in excellent wide-band wave transmission performance. Furthermore, when applied to components such as radomes and electromagnetic windows, this electromagnetic wave-transparent composite material ensures efficient transmission of multi-polarized electromagnetic waves with wide incident angles within the target frequency band, significantly improving the electromagnetic transmission efficiency of antennas, radar, and other systems. It also possesses both engineering practicality and scenario adaptability.

[0055] The above-described embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited thereto. Any simple changes or equivalent substitutions of the technical solutions that can be obviously obtained by those skilled in the art within the scope of the technology disclosed in the present invention shall fall within the scope of protection of the present invention.

Claims

1. A lightweight, high-mechanical-strength electromagnetic wave-transmitting composite material, characterized in that, The electromagnetic wave-transparent composite material is formed by arranging a plurality of basic units in a two-dimensional periodic array and integrally forming through self-pressing and laser technology. Each basic unit is a five-layer symmetrical composite structure, which comprises a honeycomb structure layer located in the middle, and metal structure layers and dielectric layers symmetrically distributed on both sides of the honeycomb structure layer in sequence. Both the honeycomb structure layer and the dielectric layer are made of a high-frequency dielectric material with a dielectric constant of 3.28 and a loss tangent of 0.002, and the metal structure layer is made of metallic copper.

2. The lightweight, high mechanical strength electromagnetic wave-transmitting composite material according to claim 1, characterized in that, The honeycomb structure layer is in the shape of a cuboid plate with a porous structure. A plurality of rows of cylindrical through holes distributed in parallel are penetratingly arranged in the honeycomb structure layer along the thickness direction, and adjacent cylindrical through holes are communicated with each other through arc-shaped grooves, so that the connection area between adjacent cylindrical through holes presents an inwardly recessed curved surface form.

3. The lightweight, high mechanical strength electromagnetic wave-transmitting composite material according to claim 2, characterized in that, The outer side of the cylindrical through hole located at the edge of the honeycomb structure layer is also provided with an inwardly recessed arc-shaped opening.

4. The lightweight, high mechanical strength electromagnetic wave-transmitting composite material according to claim 2, characterized in that, The length of the honeycomb structure layer ,width Thickness hm=6.3mm.

5. The lightweight, high mechanical strength electromagnetic wave-transmitting composite material according to claim 2, characterized in that, The axis of each cylindrical through hole is parallel to the thickness direction of the honeycomb structure layer, the radius rk of the cylindrical through hole is 1.7mm, and the thickness thereof is the same as that of the honeycomb structure layer.

6. The lightweight, high mechanical strength electromagnetic wave-transmitting composite material according to claim 1, characterized in that, The metal structure layer comprises a circular-ring-shaped metal hollow grid and a circular metal sheet. The circular metal sheet is coaxially arranged at the center of the circular-ring-shaped metal hollow grid. The thickness of the metal structure layer is 0.017mm, and the length and width thereof are both the same as those of the honeycomb structure layer.

7. The lightweight, high mechanical strength electromagnetic wave-transmitting composite material according to claim 6, characterized in that, The outer diameter rout of the central circular ring of the circular-ring-shaped metal hollow grid is 3.13mm, and the inner diameter rin thereof is 2.88mm.

8. The lightweight, high mechanical strength electromagnetic wave-transmitting composite material according to claim 7, characterized in that, The upper and lower ends of the central circular ring are symmetrically provided with a herringbone-shaped arc and two quarter-circular metal sheets. The herringbone-shaped arc is externally tangent to the central circular ring, each quarter-circular metal sheet is arranged concentrically with each arc segment of the herringbone-shaped arc, and the radius r1 of the circular metal sheet is 2mm.

9. A method for preparing a lightweight, high-mechanical-strength electromagnetic wave-transmitting composite material according to any one of claims 1-8, characterized in that, The method includes the following steps: Step 1: Laying a high-frequency dielectric material, and pressing the material to a thickness of 0.5mm through a self-pressing process to obtain a dielectric layer; Step 2: Laying a metallic copper sheet on one side of the dielectric layer, and etching out the designed structure using a laser process to obtain a metal structure layer; Step 3: Continuing to lay the high-frequency dielectric material on the side of the metal structure layer away from the dielectric layer until the laying thickness reaches 6.3mm, so as to obtain a dielectric plate with a thickness of 6.3mm, and excavating a plurality of rows of parallel-distributed cylindrical through holes on the dielectric plate according to the designed structure through a laser process to obtain the honeycomb structure layer; Step 4: Sequentially laying a metallic copper sheet and a high-frequency dielectric material on the side of the honeycomb structure layer away from the dielectric layer, so as to form a symmetrical metal structure layer and a dielectric layer on the other side of the honeycomb structure layer, and adding a prepreg between each layer of the dielectric layer, the metal structure layer and the honeycomb structure layer to realize connection between the layers.

10. The application of the lightweight and high mechanical strength electromagnetic wave-transparent composite material according to any one of claims 1 to 8 in radomes, millimeter wave communication infrastructures, stealth equipment, and electromagnetic windows.

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