Broadband flexible transparent ultrathin metasurface wave absorber

Abstract

The invention provides a broadband flexible transparent ultrathin metasurface wave absorber which comprises a first dielectric layer, a second dielectric layer and a third dielectric layer which are sequentially arranged from bottom to top, the first dielectric layer and the third dielectric layer are made of the same material, and the second dielectric layer and the first dielectric layer are made of different materials; a conductive film is arranged on the upper surface of the third dielectric layer, a plurality of conductive film units distributed in a matrix are arranged on the conductive film, each conductive film unit is of a central symmetry structure, and each conductive film unit comprises a plurality of heart-shaped structures located on the edge and sector ring structures arranged on the outer sides of the heart-shaped structures; the lower surface of the first dielectric layer is covered with a conductive film with set square resistance. According to the invention, the key technical problems of low profile, wide bandwidth, high absorption, insensitivity to polarization and angle and the like of the wave absorber can be solved.

Description

Technical Field

[0001] The present invention belongs to the field of electromagnetic signal control, and in particular relates to a broadband flexible transparent ultra-thin supersurface absorber. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] With the rapid development of millimeter-wave communications, radar detection, and electronic countermeasures, V-band (50-75 GHz) electromagnetic waves, due to their wide bandwidth and high resolution, are showing significant application value in high-speed data transmission, precision imaging, and military stealth. However, electromagnetic interference and radar scattering in this frequency band are becoming increasingly prominent, and traditional absorbing materials such as ferrites and carbon-based composites face significant challenges in V-band applications. Their absorption mechanism, based on the quarter-wavelength principle, results in excessive device thickness, making it difficult to meet the requirements of lightweight and flexible modern electronic devices. Furthermore, these materials have a narrow absorption bandwidth and poor environmental stability, making them unsuitable for complex and diverse practical application scenarios.

[0004] In recent years, metasurface absorbers have achieved efficient absorption in ultra-thin thicknesses through precise control of electromagnetic waves through subwavelength artificial structures, providing a new approach to solving the aforementioned problems. However, existing V-band metasurface absorbers still suffer from the fact that some materials lack optical transparency and exhibit rigidity, limiting their application in scenarios such as wave-transmitting windows and flexible electronics. Furthermore, defects such as polarization sensitivity, strong dependence on incident angles, high machining precision requirements, and thermal mismatch between the flexible substrate and the metal resonant layer severely restrict their practical application in cutting-edge fields such as 5G / 6G communications and smart skins. Summary of the Invention

[0005] The present invention proposes a broadband flexible transparent ultra-thin metasurface absorber, which can solve key technical problems such as low profile, wide bandwidth, high absorption, and polarization and angle insensitivity of the absorber.

[0006] According to some embodiments, the present invention adopts the following technical solutions:

[0007] A broadband flexible transparent ultrathin metasurface absorber comprises a first dielectric layer, a second dielectric layer, and a third dielectric layer arranged sequentially from bottom to top, wherein the first dielectric layer and the third dielectric layer are made of the same material, and the second dielectric layer and the first dielectric layer are made of a different material;

[0008] A conductive film is provided on the upper surface of the third dielectric layer, and a plurality of conductive film units arranged in a matrix are provided on the conductive film, each conductive film unit is a centrally symmetrical structure, and each conductive film unit includes a plurality of heart-shaped structures located at the edge and a fan-ring structure provided outside the heart-shaped structure;

[0009] The lower surface of the first dielectric layer is covered with a conductive film having a set square resistance.

[0010] As an optional implementation manner, the thickness, relative dielectric constant and loss tangent value of the first dielectric layer and the third dielectric layer are all the same.

[0011] As an optional embodiment, the first medium layer and the third medium layer are made of PET material.

[0012] As an optional implementation, the second dielectric layer is made of PVC material.

[0013] As an optional embodiment, the relative dielectric constant of the first dielectric layer and the third dielectric layer is greater than the relative dielectric constant of the second dielectric layer, the loss tangent value of the first dielectric layer and the third dielectric layer is smaller than the loss tangent value of the second dielectric layer, and the thickness of the first dielectric layer and the third dielectric layer is smaller than the thickness of the second dielectric layer.

[0014] Furthermore, the relative dielectric constant of the first dielectric layer and the third dielectric layer is 3.2, the loss tangent value is 0.002, and the thickness d is 0.175 mm.

[0015] Furthermore, the relative dielectric constant of the second dielectric layer is 2.4, the loss tangent value is 0.06, and the thickness h is 0.4 mm.

[0016] As an optional embodiment, the conductive film units are square in shape and of the same size, and are periodically arranged on the upper surface of the third dielectric layer to form a matrix structure;

[0017] Each conductive film unit includes a composite structure formed by four groups of the heart-shaped structures and the fan-ring structures.

[0018] As an optional embodiment, the heart-shaped structure is formed by vertically arranging a first part and a second part, the first part is an elliptical shape with the major axis and the minor axis as the symmetry line and the center point as the midpoint, and the major axis and the minor axis respectively coincide with the two adjacent edges of the corresponding conductive film unit, and the midpoint coincides with the endpoint of the corresponding conductive film unit, and the second part is obtained by mirroring the first part with the diagonal line between the end and the diagonal end as the axis.

[0019] As an optional embodiment, the fan ring structure is a quarter of a circle, and the diameter of the circle coincides with the edge of the corresponding conductive film unit. The fan ring structures of the same conductive film unit do not intersect with each other, and the fan ring structures do not intersect with the corresponding heart-shaped structures.

[0020] As an optional embodiment, for every four adjacent conductive film units distributed in a 2*2 pattern, each fan-ring structure at the midpoint of the four conductive film units forms a circular ring, and the center of the circular ring is the midpoint of the four conductive film units;

[0021] Each heart-shaped structure at the midpoint of the four conductive film units forms two vertically arranged elliptical shapes.

[0022] As an optional embodiment, the inner radius of the fan ring structure is 5.28 mm, and the outer radius is 5.68 mm.

[0023] As an optional embodiment, the semi-major axis length of the first part and the second part of the heart-shaped structure is 4.84 mm, and the semi-minor axis length is 2.1 mm.

[0024] As an optional embodiment, the conductive film unit is composed of an ITO resistor film with a set square resistance, and the square resistance value is greater than the square resistance value of the conductive film provided on the lower surface of the first dielectric layer.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention proposes a broadband flexible transparent metasurface absorber, which achieves the comprehensive performance of ultrathinness, broadband (50-75GHz), high absorption (>97%), flexibility and transparency through innovative material selection and structural design.

[0027] The centrally symmetrical ITO pattern on the top layer of the present invention regulates electromagnetic waves through localized surface plasmon resonance or equivalent medium theory, avoiding the thickness limitation of the traditional resonant cavity. At the same time, the middle dielectric layer adopts an optimized stack of PET-PVC-PET, combined with an extremely thin ITO conductive layer, significantly reducing the overall thickness.

[0028] The broadband absorption of the present invention is achieved through a multi-resonant coupling mechanism. The periodic arrangement of the top ITO pattern excites resonance peaks in multiple adjacent frequency bands, forming a continuous broadband absorption band. The gradient impedance matching of the multilayer dielectric reduces reflection, while the bottom low-resistance ITO film resonates with the top structure, further expanding the bandwidth. The high dielectric loss of PVC and the resistive loss of ITO work synergistically to enhance broadband energy dissipation.

[0029] The high absorption rate of the present invention relies on near-perfect impedance matching. The optimization of the equivalent electromagnetic parameters of the metasurface pattern enables a high degree of matching of the wave impedance with the free space, significantly reducing the reflectivity. At the same time, efficient energy conversion is achieved through multiple physical mechanisms such as conductive loss, dielectric loss, and multiple reflections in the resonant cavity.

[0030] The invention has flexible characteristics, which are ensured by the highly flexible polymer base of PET and PVC and the ultra-thin layered structure, and can withstand repeated bending.

[0031] The absorber provided by the present invention breaks through the limitations of traditional absorbing materials through the combined action of metasurface resonance regulation, multi-layer loss coupling and flexible transparent material integration, providing new solutions for applications such as flexible electronics, stealth technology and terahertz communication.

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0034] Figure 1 is a structural diagram of a broadband metasurface absorber according to an embodiment;

[0035] Figure 2 is a side view of a broadband metasurface absorber structure according to an embodiment;

[0036] Figure 3 is a top view of a single conductive film unit of a broadband metasurface absorber structure according to an embodiment;

[0037] Figure 4 is a schematic diagram of reflection parameters of a broadband metasurface absorber according to an embodiment;

[0038] Figure 5 is a schematic diagram of the absorptivity of a broadband metasurface absorber according to an embodiment;

[0039] Figure 6 Schematic diagram of the absorption rate of a broadband metasurface absorber at different angles according to an embodiment. DETAILED DESCRIPTION

[0040] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0041] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0042] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0043] In the absence of conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0044] Example 1

[0045] A broadband flexible transparent ultrathin metasurface absorber, such as Figure 1 As shown, a three-layer dielectric structure is adopted, including the first dielectric layer, the second dielectric layer, and the third dielectric layer arranged in order from bottom to top. Among them, the first dielectric layer and the third dielectric layer are both made of PET substrate with a relative dielectric constant of 3.2, a loss tangent value of 0.002, and a thickness of d = 0.175mm;

[0046] like Figure 2 As shown, the second dielectric layer is a PVC layer with a relative dielectric constant of 2.4, a loss tangent value of 0.06, and a thickness of h=0.4 mm; forming a PET-PVC-PET stacking structure.

[0047] The upper surface of the third dielectric layer is provided with centrosymmetric conductive film units with a period of p=12 mm, and each unit is composed of an ITO resistance film with a square resistance Rs=130Ω / sq.

[0048] like Figure 3 As shown, in this embodiment, the conductive film units are square in shape and of the same size, and are periodically arranged on the upper surface of the third dielectric layer to form a matrix structure;

[0049] Each conductive film unit includes a composite structure formed by four groups of the heart-shaped structures and the fan-ring structures. The heart-shaped structure is formed by a first part and a second part arranged vertically. The first part is an elliptical shape with the major axis and the minor axis as the symmetry line and the center point as the midpoint, and the major axis and the minor axis coincide with the two adjacent edges of the corresponding conductive film unit respectively, and the midpoint coincides with the endpoint of the corresponding conductive film unit. The second part is obtained by mirroring the first part with the diagonal line between the end and the diagonal end as the axis.

[0050] The fan-ring structure is a quarter of a circle, and the diameter of the circle coincides with the side of the corresponding conductive film unit. The fan-ring structures of the same conductive film unit do not intersect with each other, and the fan-ring structures do not intersect with the corresponding heart-shaped structures.

[0051] For every four adjacent conductive film units distributed in a 2*2 pattern, each fan-ring structure at the midpoint of the four conductive film units forms a circular ring, and the center of the circular ring is the midpoint of the four conductive film units;

[0052] Each heart-shaped structure at the midpoint of the four conductive film units forms two vertically arranged elliptical shapes.

[0053] The inner radius a of the fan ring structure is 5.28 mm, and the outer radius b is 5.68 mm.

[0054] The semi-major axis m of each part of the heart-shaped structure is 4.84 mm, and the semi-minor axis n is 2.1 mm.

[0055] The lower surface of the first dielectric layer is covered with a conductive film with a sheet resistance Rs=10Ω / sq.

[0056] The broadband flexible transparent metasurface absorber provided in this embodiment achieves the comprehensive properties of ultra-thin (0.75mm), broadband (50-75GHz), high absorption (absorption rate >97% after testing), flexibility and transparency through innovative material selection and structural design.

[0057] The centrally symmetrical ITO pattern on the top layer regulates electromagnetic waves through localized surface plasmon resonance or equivalent medium theory, avoiding the thickness limitation of the traditional resonant cavity. At the same time, the middle dielectric layer adopts an optimized stacking of PET-PVC-PET (such as PET 0.175mm per layer and PVC 0.4mm), combined with an extremely thin ITO conductive layer, significantly reducing the overall thickness.

[0058] Broadband absorption is achieved through a multi-resonant coupling mechanism. The periodic arrangement of the top ITO pattern excites resonance peaks in multiple adjacent frequency bands, forming a continuous broadband absorption band. The gradient impedance matching of the multi-layer dielectric reduces reflections, while the bottom low-resistance ITO film resonates with the top structure, further expanding the bandwidth. The high dielectric loss of PVC and the resistive loss of ITO work synergistically to enhance broadband energy dissipation.

[0059] High absorptivity relies on near-perfect impedance matching. The optimized equivalent electromagnetic parameters of the metasurface pattern ensure a close match between the wave impedance and free space (377Ω), significantly reducing reflectivity. Efficient energy conversion is achieved through multiple physical mechanisms, including conductive loss, dielectric loss, and multiple reflections in the resonant cavity. The highly flexible polymer substrate of PET and PVC and the ultra-thin layered structure ensure flexibility, allowing it to withstand repeated bending.

[0060] In summary, the absorber breaks through the limitations of traditional absorbing materials through the combined action of metasurface resonance regulation, multi-layer loss coupling and flexible transparent material integration, providing new solutions for applications such as flexible electronics, stealth technology and terahertz communications.

[0061] To demonstrate the above effect, this embodiment performs S parameter simulation in CST Studio Suite electromagnetic simulation software, and calculates the emissivity of the absorber. The reflection parameter (S11) is as follows: Figure 4 As shown, the absorption rate is Figure 5 As shown in the figure, and the absorption rate at different angles is shown in the figure Figure 6 shown.

[0062] Figure 4 is the reflection parameter of the absorber at normal incidence (0°) in the 50-75 GHz frequency band. As can be seen from the figure, the overall reflection is better than -16 dB. A reflection of less than -10 dB in the absorber is considered to meet the absorption requirements.

[0063] Figure 5 The absorption rate (under normal incidence) calculated according to the following formula is better than 97.5% overall (more than 90% is required to meet the absorption requirements), showing good absorption effect. The low-resistance ITO square film at the bottom of the absorber is generally regarded as a reflective base in simulation, with a transmission of 0, that is, S21 is 0, |S 11 | 2 is the reflectivity.

[0064] A=1-|S 11 | 2 -|S 21 | 2 .

[0065] Figure 6 is the absorption rate at different incident angles. In the incident range of 0-40°, the absorber can still maintain 90% of the absorption effect, which proves that the absorber has good angle stability.

[0066] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made by those skilled in the art that fall within the spirit and principles of the present invention and do not require creative effort are intended to be within the scope of protection of the present invention.

Claims

1. A broadband flexible transparent ultrathin supersurface absorber, characterized by: The first dielectric layer comprises a first dielectric layer, a second dielectric layer and a third dielectric layer arranged in sequence from bottom to top, wherein the first dielectric layer and the third dielectric layer are made of the same material, and the second dielectric layer and the first dielectric layer are made of different materials; A conductive film is provided on the upper surface of the third dielectric layer, and a plurality of conductive film units arranged in a matrix are provided on the conductive film, each conductive film unit is a centrally symmetrical structure, and each conductive film unit includes a plurality of heart-shaped structures located at the edge and a fan-ring structure provided outside the heart-shaped structure; The lower surface of the first dielectric layer is covered with a conductive film having a set square resistance.

2. The broadband flexible transparent ultrathin supersurface absorber according to claim 1, characterized in that: The first dielectric layer and the third dielectric layer have the same thickness, relative dielectric constant and loss tangent value.

3. The broadband flexible transparent ultra-thin supersurface absorber according to claim 1, characterized in that: The first medium layer and the third medium layer are made of PET material; The second dielectric layer is made of PVC material.

4. The broadband flexible transparent ultrathin supersurface absorber according to claim 1, characterized in that: The relative dielectric constants of the first dielectric layer and the third dielectric layer are greater than the relative dielectric constant of the second dielectric layer, the loss tangent values of the first dielectric layer and the third dielectric layer are smaller than the loss tangent value of the second dielectric layer, and the thicknesses of the first dielectric layer and the third dielectric layer are smaller than the thickness of the second dielectric layer.

5. The broadband flexible transparent ultra-thin supersurface absorber according to claim 1, characterized in that: The relative dielectric constant of the first dielectric layer and the third dielectric layer is 3.2, the loss tangent value is 0.002, and the thickness d is 0.175 mm; The second dielectric layer has a relative dielectric constant of 2.4, a loss tangent of 0.06, and a thickness h of 0.4 mm.

6. The broadband flexible transparent ultrathin supersurface absorber according to claim 1, characterized in that: The conductive film units are square in shape and of the same size, and are periodically arranged on the upper surface of the third dielectric layer to form a matrix structure; Each conductive film unit includes a composite structure formed by four groups of the heart-shaped structures and the fan-ring structures; Alternatively, the conductive film unit is formed of an ITO resistance film with a set square resistance, and the square resistance is greater than the square resistance of the conductive film disposed on the lower surface of the first dielectric layer.

7. The broadband flexible transparent ultrathin supersurface absorber according to claim 1, characterized in that: The heart-shaped structure is formed by a first part and a second part arranged vertically. The first part is an elliptical shape with the major axis and the minor axis as the symmetry line and the center point as the midpoint, and the major axis and the minor axis coincide with the two adjacent sides of the corresponding conductive film unit respectively, and the midpoint coincides with the endpoint of the corresponding conductive film unit. The second part is obtained by mirroring the first part with the diagonal line between the end and the diagonal end as the axis.

8. The broadband flexible transparent ultrathin supersurface absorber according to claim 1, characterized in that: The fan ring structure is a quarter of a circle, and the diameter of the circle coincides with the side of the corresponding conductive film unit. The fan ring structures of the same conductive film unit do not intersect with each other, and the fan ring structure does not intersect with the corresponding heart-shaped structure.

9. The broadband flexible transparent ultra-thin supersurface absorber according to claim 1, characterized in that: For every four adjacent conductive film units distributed in a 2*2 pattern, each fan-ring structure at the midpoint of the four conductive film units forms a circular ring, and the center of the circular ring is the midpoint of the four conductive film units; Each heart-shaped structure at the midpoint of the four conductive film units forms two vertically arranged elliptical shapes.

10. The broadband flexible transparent ultra-thin supersurface absorber according to claim 1, characterized in that: The inner radius of the fan ring structure is 5.28 mm and the outer radius is 5.68 mm; The semi-major axis length of the first part and the second part of the heart-shaped structure is 4.84 mm, and the semi-minor axis length is 2.1 mm.

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