A tunable integrated metamaterial structure for absorbing and reflecting waves

Abstract

This invention belongs to the field of metamaterials technology, specifically relating to an adjustable integrated absorption and reflection metamaterial structure. It includes several basic units arranged in a periodic array. Each basic unit comprises a resonant unit, a dielectric layer, and a reflector layer stacked sequentially. The dielectric layer is deformable to create a cavity between itself and the reflector layer or to fit tightly against it. The resonant unit includes four sequentially connected arc-shaped segments arranged centrally symmetrically. The ends of adjacent arc-shaped segments connect to form sharp corners extending towards the center of the resonant unit, with a gap between opposing sharp corners. This invention offers good reconfigurability, high flexibility, and deformability, allowing for easy adjustment of the state and switching of operating modes according to actual usage needs, achieving broadband absorption or complete reflection functions from 4.9 GHz to 16.3 GHz.

Description

Technical Field

[0001] This invention belongs to the field of metamaterials technology, specifically relating to an adjustable integrated metamaterial structure for absorbing and reflecting waves. Background Technology

[0002] Metamaterials are artificial composite materials composed of periodically arranged subwavelength units. By designing the structure, size, and arrangement of these units, physical properties not found in existing natural materials can be obtained. Examples include negative magnetic permeability, negative permittivity, negative refractive index, and the inverse Doppler effect. Metamaterial absorbers, as an important branch, are widely used in electromagnetic shielding, stealth technology, and energy harvesting.

[0003] Most current metamaterial absorbers are made of rigid substrates such as FR-4, which have drawbacks such as poor reconfigurability, complex fabrication, and high cost. In addition, some existing metamaterial absorbing structures have poor polarization stability and impedance matching, resulting in relatively poor absorption performance under different polarizations and incident angles. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an adjustable integrated metamaterial structure for absorbing and reflecting waves with excellent polarization stability, better impedance matching, good reconfigurability, high flexibility and deformability, and easy adjustment of state to switch usage modes according to actual usage needs.

[0005] The present invention includes a number of basic units arranged in a periodic array. Each basic unit includes a resonant unit, a dielectric layer and a reflector stacked in sequence. The dielectric layer is deformable so that it has a cavity between itself and the reflector or is tightly attached to the reflector.

[0006] The resonant unit includes four arc-shaped segments connected to each other in sequence. The four arc-shaped segments are arranged in a centrally symmetrical manner. The ends of adjacent arc-shaped segments are connected to form sharp corners extending toward the center of the resonant unit, and there is a gap between two opposite sharp corners.

[0007] Furthermore, the arc segment is a perfect circle, which provides better polarization stability.

[0008] Furthermore, the central angle corresponding to the opening region of a single arc segment is 90°, resulting in better impedance matching in the absorption mode.

[0009] Furthermore, the medium layer includes a middle plate and side plates disposed at both ends of the middle plate. The side plates and the reflector are fixed relative to each other. The side plates can be bent or laid flat between the middle plate and the medium layer so that there is a cavity between the medium layer and the reflector or that the medium layer is tightly attached to the reflector.

[0010] Furthermore, when the arc segment is a perfect circular arc, the radial width of the perfect circular arc is 40% of the outer radius of the perfect circular arc, and the outer radius of the perfect circular arc is 25% of the side length of the middle plate.

[0011] Furthermore, when there is a cavity between the dielectric layer and the reflector, the ratio of the height of the side plate to the side length of the middle plate is 0.6:1.

[0012] Furthermore, the material of the medium layer is paper.

[0013] Furthermore, the resonant unit is made of conductive ink and is installed on the dielectric layer by 3D printing.

[0014] Furthermore, the dielectric layer of several basic units is integrally disposed, and the reflector of several basic units is integrally disposed.

[0015] The beneficial effects of this invention are as follows: the resonant unit is composed of four identical rings with openings connected end to end. This structure exhibits extremely high symmetry and excellent polarization stability. The openings in the rings enhance resonance, and the basic unit achieves good impedance matching under compressed conditions. It demonstrates high absorption performance under different polarizations and incident angles, achieving a wide absorption frequency range and excellent absorption effect. The structure is highly reconfigurable, offering high flexibility and adaptability, allowing for easy adjustment of usage modes according to actual needs. It can achieve broadband absorption or complete reflection functions from 4.9GHz to 16.3GHz. In military applications, it can reduce radar cross section (RCS) for stealth effects. In civilian applications, it can enhance electromagnetic radiation protection, absorbing excess electromagnetic radiation in this band generated by some equipment, reducing its impact on humans or surrounding equipment. Furthermore, the overall structure is simple, low-cost, and easy to manufacture, possessing great application potential in military, environmental protection, and electromagnetic interference prevention fields. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the compressed state of the basic unit of the present invention.

[0017] Figure 2 This is a schematic diagram of the basic unit of the present invention under tension.

[0018] Figure 3 This is a top view of the middle part of the medium layer in the stretched state of the basic unit of the present invention.

[0019] Figure 4 This is a top view of the entire base unit under tension according to the present invention.

[0020] Figure 5 This is the equivalent impedance in the compressed state of this invention.

[0021] Figure 6 This is the equivalent impedance in the tensile state of the present invention.

[0022] Figure 7 This is a graph showing the absorption characteristics of the present invention under tensile and compressive states.

[0023] Figure 8 This is a graph showing the absorption characteristics of the present invention under different polarizations in the tensile and compressive states.

[0024] Figure 9 This is a graph showing the absorption characteristics of the present invention under different incident angles in the tensile and compressed states.

[0025] Figure 10 This is a top view of the middle part of the dielectric layer in Comparative Example 1.

[0026] Figure 11 This is a top view of the middle part of the dielectric layer in Comparative Example 2.

[0027] Figure 12 This is a top view of the middle part of the dielectric layer in Comparative Example 3.

[0028] Figure 13 This is a top view of the middle part of the dielectric layer in Comparative Example 4.

[0029] Figure 14 This is a top view of the middle part of the dielectric layer in Comparative Example 5.

[0030] Figure 15 This is a graph showing the absorption characteristics of the present invention and all comparative examples under compressed conditions.

[0031] In the diagram: 1. Resonant unit; 11. Arc segment; 12. Sharp corner; 2. Dielectric layer; 21. Middle plate; 22. Side plate; 3. Reflector; 4. Cavity. Detailed Implementation

[0032] Example 1

[0033] like Figures 1-9As shown, this invention provides an adjustable integrated metamaterial structure for absorbing and reflecting waves, comprising several basic units arranged in a periodic array. Each basic unit includes a resonant unit 1, a dielectric layer 2, and a reflector 3 stacked from top to bottom. The dielectric layer 2 is deformable, such as by bending or flattening, thereby creating a cavity 4 between the dielectric layer 2 and the reflector 3 or allowing it to be tightly fitted to the reflector 3. The two ends of the dielectric layer 2 are fixed relative to the reflector 3, specifically by directly attaching it to the reflector 3 with an adhesive layer, or by clamping or limiting it with an external structure, so that the two ends of the dielectric layer 2 are in contact with the reflector 3 and remain in a relatively fixed state. The resonant unit 1 is specifically located in the middle of the side of the dielectric layer 2 facing away from the reflector 3. The resonant unit 1 includes four arc-shaped segments 11 whose ends are connected to each other in sequence. The four arc-shaped segments 11 are arranged centrally symmetrically, and the ends of adjacent arc-shaped segments 11 form sharp corners 12 extending toward the center of the resonant unit 1, with a gap between two opposite sharp corners 12.

[0034] The state of dielectric layer 2 after the first deformation is as follows Figure 1 As shown, the two ends of the dielectric layer 2 are bent, and there is a cavity 4 between the side of the dielectric layer 2 away from the resonant unit 1 and the reflector 3. The basic unit is in a compressed state, and the whole forms an absorbing structure. The air in the cavity 4 also has a certain effect on impedance matching. The reflector 3, as the bottom conductive reflective layer, is made of a metal material with strong electromagnetic wave reflection effect, which can ensure that no electromagnetic wave is transmitted. The electromagnetic waves that enter the absorbing structure are all lost due to dielectric loss and ohmic loss.

[0035] The state of dielectric layer 2 after the second deformation is as follows Figure 2 As shown, the dielectric layer 2 is stretched out, with the middle and both ends of the dielectric layer 2 laid flat. At this time, the side of the dielectric layer 2 away from the resonant unit 1 is in contact with the reflector 3, and the basic unit is in a stretched state, forming a reflective structure as a whole. Since the resonant unit 1 and the reflector 3 do not resonate, the loss of electromagnetic waves is very small, and electromagnetic waves can be effectively reflected.

[0036] Based on the above configuration, switching between absorption and reflection modes can be achieved by folding or stretching the dielectric layer 2. This provides good reconfigurability, high flexibility, and adaptability, allowing for easy adjustment of the state and switching of operating modes according to actual needs. The resonant unit 1 consists of four identical rings with openings connected end-to-end. This structure exhibits extremely high symmetry and excellent polarization stability. Furthermore, the openings in the rings enhance resonance, enabling good impedance matching of the base unit under compressed conditions. This results in a wide absorption frequency range and excellent absorption effect. The overall structure is simple, low-cost, small in size, and easy to manufacture, making it highly promising for applications in military, environmental protection, and electromagnetic interference prevention.

[0037] In practical applications, the two ends of the dielectric layer 2 can be fixed to the reflector 3 using a reusable adhesive layer. When switching usage modes, the dielectric layer 2 is separated from the reflector 3, the dielectric layer 2 is compressed or stretched, and then its two ends are fixed back to the reflector 3 to achieve the switching of usage modes. This method is simple and low-cost, and suitable for small-scale civilian use or related research. In other applications, the two ends of the dielectric layer 2 are fixed to the reflector 3 using a clamping structure or mechanical fixing structure. When switching usage modes, the clamping structure or mechanical fixing structure is released, the dielectric layer 2 is compressed or stretched, and then its two ends are fixed back to the reflector 3 to achieve the switching of usage modes. This method is suitable for some highly automated application scenarios.

[0038] The dielectric layer 2 specifically includes a middle plate 21 and side plates 22 disposed at both ends of the middle plate 21, with the side plates 22 and the reflector 3 fixed relative to each other. The middle plate 21 is the middle part of the dielectric layer 2, and the side plates 22 are the two ends of the dielectric layer. The side plates 22 and the middle plate 21 can be bent or laid flat to create a cavity 4 between the dielectric layer 2 and the reflector 3 or to be tightly fitted to the reflector 3. The resonant unit 1 is specifically disposed on the surface of the middle plate 21, that is, on the side of the middle plate 21 facing away from the reflector 3.

[0039] In this invention, the dielectric layer 2 is made of paper with a thickness td of 0.208 mm, a dielectric constant of 2.31, and a loss tangent of 0.035. Wood pulp paper can be used. By using paper as the dielectric layer 2, compared to conventional rigid materials, the dielectric layer 2 of this invention is lower in cost and easier to process. This not only ensures high reconfigurability of the basic unit but also allows the basic unit to conformally attach to complex and irregular object surfaces, broadening the application scenarios of this invention.

[0040] The resonant unit 1 is formed from conductive ink containing metallic elements, and the conductivity of this conductive ink is 700 S / m. Based on this, the resonant unit 1 can be printed onto the dielectric layer 2, a simple, inexpensive, and environmentally friendly process. Specifically, the resonant unit 1 is 3D printed onto the dielectric layer 2 to ensure that the resonant unit 1 has the appropriate thickness.

[0041] The thickness ts of the reflector 3 is 0.035 mm. In the compressed state, the side plate 22 is perpendicular to the middle plate 21, and the dielectric layer 2 is arched like a doorway. The dimension of the reflector 3 corresponding to the width of the dielectric layer 2 and the side length of the middle plate 21 are both 'a', where 'a' is 10 mm. The height difference h between the surface of the dielectric layer 2 and the reflector 3 is 6 mm, meaning the height of the side plate 22 is 6 mm. The cavity 4 between the dielectric layer 2 and the reflector 3 is rectangular, and its height is 5.792 mm. In the stretched state, the dielectric layer 2 is in a flat state, with its side facing away from the resonant unit 1 in contact with the surface of the reflector 3. The dimension of the reflector 3 corresponding to the width of the dielectric layer 2 is a + 2h.

[0042] The arc segment 11 is specifically a perfect circular arc, which provides better polarization stability. The central angle corresponding to the opening area of ​​a single arc segment 11 is 90°, resulting in better impedance matching. The dimensions of the resonant unit 1 are as follows: iur = 1.5mm, our = 2.5mm, tm = 0.05mm, d = 4mm. Wherein, iur is the inner radius of the perfect circular arc, our is the outer radius of the perfect circular arc, tm is the thickness of the perfect circular arc (i.e., the thickness of the resonant unit 1), d is the interval between the two opposite sharp corners 12 (i.e., the minimum inner diameter of the resonant unit 1), and the radial width of the perfect circular arc is the difference between the outer radius and the inner radius, specifically 1mm.

[0043] In this invention, the inner side of the end opposite to one of the individual pointed corners 12 is a plane perpendicular to the dielectric layer 2. The reflector 3 is made of copper with a conductivity of 5.96 × 10⁻⁶. 7 S / m. Under compression, the period length of each basic unit is 10mm.

[0044] In this invention, the dielectric layers 2 of several basic units are integrally formed, meaning that the dielectric layers 2 of several basic units are different areas of the same sheet of paper. The reflective plates 3 of several basic units are integrally formed, meaning that the reflective plates 3 of several basic units are different areas of the same metal plate, and the area of ​​this metal plate is larger than the area of ​​all the sheets of paper containing the dielectric layers 2, to ensure that, under tension, each dielectric layer 2 has a corresponding reflective plate 3 below it. The compression direction of the dielectric layer 2 is... Figure 1 The left and right directions are the line directions connecting the two side plates 22. Preferably, a crease is preset between the middle plate 21 and the side plate 22 of a single base unit, and a crease is preset between the dielectric layers 2 of two adjacent base units in the compression direction, so that when switching modes, the dielectric layer 2 of a single base unit and the dielectric layers 2 of all base units can be compressed in a predetermined shape.

[0045] When the present invention is in a compressed state, its equivalent impedance is as follows: Figure 5 As shown, in the compressed state, within the frequency range of 4.9GHz to 16.3GHz, the real part is close to 1 and the imaginary part is close to 0, indicating that the present invention has better impedance matching effect in the compressed state, a wide effective absorption frequency range, and an absorption effect of more than 90% in the frequency range of 4.9GHz to 16.3GHz, that is... Figure 7 As shown. When the present invention is in a stretched state, its equivalent impedance is as follows: Figure 6 As shown, the real and imaginary parts are mostly zero, but there is a large jump around 10.5 GHz. This indicates that the impedance matching effect of this invention is very poor in the stretched state. Figure 7As shown, the absorption rate of the stretch mode of this invention is less than 3% across the entire frequency band, which can be regarded as a complete reflection function.

[0046] like Figure 8 As shown, it can be seen that the TE polarization and TM polarization of the incident electromagnetic wave have little effect on the present invention, indicating that the present invention has excellent polarization insensitivity characteristics, and combined with Figure 9 As shown, it can be seen that the present invention has high absorption performance under different polarization and incident angle conditions.

[0047] Comparative Example 1

[0048] Figure 10 The resonant unit configuration of Comparative Example 1 is shown. Compared with Example 1, the difference is that the resonant unit of Comparative Example 1 has a rectangular structure in the middle connecting the two opposite sharp corners. Otherwise, the size and material of the resonant unit of Comparative Example 1 are the same as those of Example 1, and its dielectric layer and reflector are also the same as those of Example 1.

[0049] Comparative Example 2

[0050] Figure 11 The resonant unit configuration of Comparative Example 2 is shown below. This Comparative Example 2 resonant unit uses four open-frame structures connected end-to-end by straight line segments. The dimensions are aa=0.44mm, bb=2.42mm, cc=3.3mm, dd=2.2mm, and ee=3.08mm. The material and thickness of its resonant unit are the same as in Example 1, as are the dielectric layer and reflector.

[0051] Comparative Example 3

[0052] Figure 12 The resonant unit configuration of Comparative Example 3 is shown. Compared with Example 1, the difference lies in the number of arc segments in Comparative Example 3, which is three. The material, inner diameter, outer diameter, and thickness of the arc segments are the same as those in Example 1, and the dielectric layer and reflector are also the same as those in Example 1.

[0053] Comparative Example 4

[0054] Figure 13 The resonant unit configuration of Comparative Example 4 is shown. Compared with Example 1, the difference is that the number of arc segments in Comparative Example 4 is different, specifically five. The material, inner diameter, outer diameter and thickness of the arc segments are the same as those in Example 1, and the dielectric layer and reflector are also the same as those in Example 1.

[0055] Comparative Example 5

[0056] Figure 14The resonant unit configuration is shown in Comparative Example 5. Compared to Example 1, the difference lies in that the arc segments in Comparative Example 5 are connected by straight segments, with dimensional parameters a1=1.75mm, b1=1.25mm, e1=5.5mm, and f1=0.5mm. The material and thickness of its resonant unit are the same as in Example 1, as are the dielectric layer and reflector.

[0057] The absorption effect of the present invention and the above comparative examples 1-5 under compressed conditions is as follows: Figure 15 As shown. Comparative Example 1 has an absorption rate greater than 90% in the frequency range of 5.3GHz to 8.8GHz; Comparative Example 2 has an absorption rate less than 90% in all frequencies; Comparative Example 3 has an absorption rate greater than 90% in the frequency range of 8.1GHz to 16.9GHz; Comparative Example 4 has an absorption rate greater than 90% in the frequency range of 6.8GHz to 10.8GHz; and Comparative Example 5 has an absorption rate greater than 90% in the frequency range of 7.5GHz to 14.5GHz. The present invention achieves an absorption effect greater than 90% in the frequency range of 4.9GHz to 16.3GHz, significantly better than Comparative Examples 1-5, achieving a wider absorption frequency range and better absorption effect.

[0058] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of protection of this application is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of one or more embodiments of this application as described above, which are not provided in detail for the sake of brevity.

[0059] One or more embodiments in this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments in this application should be included within the protection scope of this application.

Claims

1. An tunable integrated metamaterial structure for absorbing and reflecting waves, characterized in that, It includes several basic units arranged in a periodic array. Each basic unit includes a resonant unit (1), a dielectric layer (2) and a reflector (3) stacked in sequence. The dielectric layer (2) includes a middle plate (21) and side plates (22) disposed at both ends of the middle plate (21). The side plates (22) and the reflector (3) are relatively fixed. The side plates (22) and the middle plate (21) can be bent so that the dielectric layer (2) can be deformed so that there is a cavity (4) between the dielectric layer (2) and the reflector (3). The resonant unit (1) is disposed on the side of the middle plate (21) away from the reflector (3). The resonant unit (1) includes four arc segments (11) connected to each other in sequence. The four arc segments (11) are arranged in a centrally symmetrical manner. The end connection of adjacent arc segments (11) forms a sharp corner (12) extending toward the center of the resonant unit (1), and there is a gap between two opposite sharp corners (12). The arc segment (11) is a perfect arc. The central angle corresponding to the opening area of ​​a single arc segment (11) is 90°. The inner side of the end of a single sharp corner (12) opposite to another sharp corner (12) is a plane perpendicular to the dielectric layer (2).

2. The tunable integrated metamaterial structure for absorbing and reflecting waves as described in claim 1, characterized in that, When the arc segment (11) is a perfect circular arc, the radial width of the perfect circular arc is 40% of the outer radius of the perfect circular arc, and the outer radius of the perfect circular arc is 25% of the side length of the middle plate (21).

3. The tunable integrated metamaterial structure for absorbing and reflecting waves as described in claim 1, characterized in that, When there is a cavity (4) between the medium layer (2) and the reflector (3), the ratio of the height of the side plate (22) to the side length of the middle plate (21) is 0.6:

1.

4. The tunable integrated metamaterial structure for absorbing and reflecting waves as described in any one of claims 1-3, characterized in that, The medium layer (2) is made of paper.

5. The tunable integrated metamaterial structure for absorbing and reflecting waves as described in claim 4, characterized in that, The resonant unit (1) is made of conductive ink and is installed on the dielectric layer (2) by 3D printing.

6. The tunable integrated metamaterial structure for absorbing and reflecting waves as described in claim 4, characterized in that, The dielectric layer (2) of several basic units is integrally disposed, and the reflector (3) of several basic units is integrally disposed.

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