Transparent multi-band electromagnetic metasurface and applications thereof

Abstract

The application relates to a transparent multi-band electromagnetic super-holographic surface and application thereof. The super-holographic surface comprises a transparent base layer, at least one surface of the transparent base layer being overlaid with an electromagnetic response layer; the electromagnetic response layer comprises a plurality of groups of electromagnetic response layer subunits arranged in a periodic array, each group of the electromagnetic response layer subunits comprising a plurality of conductive units of different sizes arranged in a nested mode, the size of each conductive unit being smaller than one half of a working wavelength, and each conductive unit being made of transparent conductive material with electromagnetic response capability; the conductive units of different sizes can form resonant responses of corresponding frequency band electromagnetic waves, so that the equivalent input impedance at multiple frequency bands is matched with the impedance of free space, thereby canceling the reflection at the interface. By arranging the plurality of conductive units of different sizes arranged in a nested mode, the application not only solves the problem of high-frequency signal blocking, but also realizes the transmission enhancement of multiple frequency band electromagnetic waves.

Description

Technical Field

[0001] This application relates to the field of signal transmission technology, and in particular to a transparent multi-band electromagnetic antireflective metasurface and its applications. Background Technology

[0002] As wireless communication systems continue to evolve, communication services have gradually expanded from traditional low-frequency bands to higher frequency bands, typically including the Sub-6GHz band, Wi-Fi band, and millimeter-wave band. In applications such as indoor building coverage, in-vehicle communication coverage, and communication coverage through glass curtain walls, electromagnetic waves often need to pass through transparent components such as glass windows, curtain wall glass, and vehicle windows to reach the target area. However, when electromagnetic waves propagate from free space to transparent media such as glass, reflection usually occurs at the interface due to the difference in electromagnetic parameters between the two. Simultaneously, the medium itself may introduce absorption losses, resulting in a decrease in the signal strength transmitted into the room or vehicle. This effect is particularly pronounced at higher frequency bands, where transparent components have a more significant impact on electromagnetic wave propagation, thereby affecting wireless link quality, coverage, and communication stability.

[0003] To address the above problems, existing technologies mainly offer the following solutions: 1. Active signal enhancement solutions: These include signal compensation achieved through signal amplifiers, indoor distribution systems, and repeater equipment. While these solutions can improve coverage, they typically suffer from high equipment costs, complex deployment, high energy consumption, and demanding maintenance requirements.

[0004] 2. Traditional passive metal electromagnetic structure solutions: such as using metal frequency-selective structures and metal metasurfaces to improve electromagnetic transmission or reflection characteristics. However, these structures are usually opaque or have poor transparency, making them unsuitable for large-scale deployment in glass curtain walls, windows, and other scenarios where lighting and visual appearance are important.

[0005] 3. Transparent Electromagnetic Functional Structure Scheme: Existing transparent conductive films, transparent metasurfaces, or transparent frequency-selective structures have achieved a certain balance between optical transparency and electromagnetic control capabilities. However, many schemes are mainly optimized for a single frequency point or a single frequency band, and their adaptability to scenarios that simultaneously cover multiple commonly used communication frequency bands is insufficient. In addition, in multi-frequency control design, it is often difficult to balance transparency, transmission enhancement performance, polarization stability, and large-area manufacturability.

[0006] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0007] Based on this, this application provides a transparent multi-band electromagnetic antireflective metasurface, which not only solves the problem of high-frequency signal blocking, but also enables the transmission enhancement of electromagnetic waves in multiple frequency bands.

[0008] To achieve the above objectives, embodiments of this application provide a transparent multi-band electromagnetic antireflection metasurface, comprising: a transparent substrate layer, wherein at least one surface of the transparent substrate layer is superimposed with an electromagnetic response layer; The electromagnetic response layer includes several groups of electromagnetic response layer sub-units arranged in a periodic array. Each group of electromagnetic response layer sub-units includes multiple conductive units of different sizes nested together. The size of each conductive unit is less than half of the working wavelength. Each conductive unit is made of a transparent conductive material with electromagnetic response capability. The conductive units of different sizes can form a resonant response to electromagnetic waves of corresponding frequency bands, so that the equivalent input impedance at multiple frequency bands matches the free space impedance, thereby canceling the reflection at the interface and realizing the transmission enhancement of electromagnetic waves at multiple frequency bands.

[0009] Preferably, by adjusting the size, linewidth, ring spacing, and unit period of the conductive unit, the equivalent input impedance of the metasurface at the target frequency band is made closer to the free space impedance.

[0010] Preferably, each of the conductive units adopts a rotationally symmetric design to achieve insensitivity to the polarization direction of the incident electromagnetic wave.

[0011] Preferably, each of the conductive units is designed as a circular ring, square ring, cross, or regular hexagon.

[0012] Preferably, the arrangement of the electromagnetic response layer sub-units includes periodic interval arrangement, close splicing arrangement, or square lattice, hexagonal lattice, or partitioned mixed arrangement.

[0013] Preferably, the outer surface of the electromagnetic response layer is superimposed with a transparent protective layer to prevent the electromagnetic response layer from being mechanically scratched or oxidized and corroded.

[0014] Preferably, the transparent substrate layer is made of a highly transparent flexible material or is glass.

[0015] Preferably, the flexible material is PET or COC.

[0016] Preferably, the transparent conductive material is indium tin oxide, graphene, silver nanowires, or a metal mesh.

[0017] This application also provides an application of a transparent multi-band electromagnetic anti-reflective metasurface, which is used in architectural glass, curtain wall glass, vehicle window glass or transparent partitions.

[0018] The transparent multi-band electromagnetic antireflective metasurface provided by this invention has the following advantages and beneficial effects: The electromagnetic response layer of this application is composed of periodically arrayed conductive units. When an incident electromagnetic wave of a specific frequency acts on this structure, an electromagnetic response is induced on the surface of the sub-units, making the equivalent input impedance match the free space impedance, thereby canceling the reflection at the interface of the transparent substrate layer and realizing the transmission enhancement of electromagnetic waves in a specific frequency band. The reflection of the incident electromagnetic wave at the interface of the transparent substrate layer is suppressed, and the transmission coefficient approaches 1, thereby realizing the non-destructive or low-destructive transmission of electromagnetic waves, thus effectively solving the problem of traditional glass blocking high-frequency signals.

[0019] Meanwhile, this application sets multiple nested conductive units of different sizes within the electromagnetic response layer subunit, so that the nested conductive units of different sizes form different resonant modes at different frequency positions, thereby enabling transmission enhancement of multiple target frequency bands.

[0020] To ensure optical transparency, the electromagnetic response layer uses transparent conductive materials such as indium tin oxide, graphene, or extremely fine metal mesh.

[0021] To improve durability, a transparent protective layer is added to the outside of the electromagnetic response layer to prevent physical damage and environmental erosion. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of a first embodiment of the transparent multi-band electromagnetic antireflective metasurface of this application.

[0023] Figure 2 This is a schematic diagram of the structure of the second embodiment of the transparent multi-band electromagnetic antireflective metasurface of this application.

[0024] Figure 3 This is a schematic diagram of the square ring nesting of conductive units in the transparent multi-band electromagnetic antireflective metasurface of this application.

[0025] Figure 4 This is a schematic diagram of the hexagonal nesting of conductive units in the transparent multi-band electromagnetic antireflective metasurface of this application.

[0026] Figure 5 This is a schematic diagram of the ring-nested conductive units in the transparent multi-band electromagnetic antireflective metasurface of this application.

[0027] Figure 6 This is a schematic diagram of the cell spacing arrangement of the conductive units in the transparent multi-band electromagnetic antireflective metasurface of this application.

[0028] Figure 7 This is a schematic diagram of the close arrangement of conductive units in the transparent multi-band electromagnetic antireflective metasurface of this application. Detailed Implementation

[0029] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate preferred embodiments of the application. However, this application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0030] It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to and integrated with the other component, or there may be an intervening component present. The term "mounted" and similar expressions used in this document are for illustrative purposes only.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0032] In one embodiment, such as Figure 1 As shown, a transparent multi-band electromagnetic antireflection metasurface is provided, comprising: a transparent substrate layer 100, on the surface of which an electromagnetic response layer 200 is superimposed; the electromagnetic response layer 200 includes several groups of electromagnetic response layer sub-units arranged in a periodic array, each group of electromagnetic response layer sub-units including multiple conductive units of different sizes nested together, each conductive unit having a size less than half the operating wavelength, and each conductive unit using a transparent conductive material with electromagnetic response capability; the conductive units of different sizes can form a resonant response to electromagnetic waves of corresponding frequency bands, so that the equivalent input impedance at multiple frequency bands matches the free space impedance, thereby canceling reflections at the interface and realizing transmission enhancement of electromagnetic waves at multiple frequency bands.

[0033] The transmission enhancement mechanism of this application can be understood from two aspects: impedance matching and multimode resonance.

[0034] I. Impedance Matching Mechanism. When an electromagnetic wave is incident from free space onto the interface of a transparent medium such as glass, reflection occurs at the interface due to the difference between the free space impedance and the equivalent input impedance of the medium. If a designed electromagnetic response layer is introduced near the interface, this layer will generate an induced current under the action of the incident electromagnetic wave and exhibit additional equivalent surface conductance / susceptance characteristics. By adjusting the unit structure and its arrangement, the overall equivalent input impedance of the system can be made closer to the free space impedance in the target frequency band, thereby reducing reflection and improving transmission efficiency.

[0035] II. Multi-band Resonance Mechanism. This invention utilizes nested electromagnetic response sub-units of varying sizes to create different resonance modes at different frequency positions. Specifically, the larger outer ring preferably corresponds to a lower frequency resonance response, while the smaller inner ring preferably corresponds to a higher frequency resonance response. Therefore, this application achieves resonance construction and transmission enhancement at multiple target frequencies within a single transparent metasurface unit through nested electromagnetic response structures. Furthermore, by collaboratively optimizing the geometry, linewidth, ring spacing, and unit period of each ring, the coupling relationship between different resonance modes can be adjusted to optimize the position, bandwidth, and transmission peak of multiple target frequencies.

[0036] III. Mechanism for Achieving Transparency. To balance electromagnetic functionality and visual transparency, the electromagnetic response layer 200 of this application preferably uses a transparent conductive material, or a transparent mesh-like conductive structure with fine linewidth and high aperture ratio. Through material selection and microstructure design, the impact on visible light transmission and visual appearance can be reduced while ensuring a certain level of conductive response.

[0037] Of course, in order to further eliminate reflections at the two interfaces of the transparent substrate 100 (glass) (air-front glass surface, rear glass surface-air), this application simultaneously deploys electromagnetic response layers 200 on both outer surfaces of the transparent substrate 100 to achieve bidirectional electromagnetic wave incident anti-reflection, such as... Figure 2 As shown.

[0038] The electromagnetic response layer 200 can be formed on the transparent substrate 100 in the following ways: after forming a transparent conductive film on the surface of the transparent substrate 100, the conductive unit pattern is formed by photolithography, etching, laser processing, etc.; conductive patterns are formed on the transparent substrate 100 by printing, spraying, transfer, etc.; it is first formed on an independent transparent film and then attached to the surface of a glass component; or the electromagnetic response layer is directly deposited or processed on the surface of the target glass component. The transparent metasurface of the present invention can be prepared by one or a combination of the following methods: In practice, by designing the dimensions, linewidth, ring spacing, unit period, and material parameters of each nested electromagnetic response structure, the equivalent input impedance of the metasurface-transparent medium composite structure at multiple target frequency points can be made closer to the free space impedance, thereby reducing interface reflection and improving transmission performance, and realizing multi-frequency anti-reflection within the same transparent metasurface unit.

[0039] To achieve multi-band operation, the conductive units employ a multi-ring nesting method. For example... Figure 3-5 As shown, a complete unit contains two or more ring structures.

[0040] Subwavelength size: The physical period P of the cell should be smaller than the operating wavelength λ (typically λ / 10 to λ / 2) to avoid generating higher-order diffraction modes and ensure that the metasurface behaves as a uniform equivalent dielectric layer.

[0041] Multi-ring for multi-band anti-reflection: When the unit adopts a nested structure of three or more rings, each nested electromagnetic response structure of different sizes corresponds to a resonant mode at a different frequency position, thereby achieving transmission enhancement near multiple target frequency points.

[0042] Parameter Co-optimization: Electromagnetic simulation is used to scan and optimize the geometric parameters of each ring, including the number of rings, ring size, line width, ring spacing and unit period, so as to independently or coupled control the position and transmission enhancement of each resonant frequency point to align it with the target communication frequency point.

[0043] In practical implementation, to ensure good response characteristics to electromagnetic waves (TE waves and TM waves) with different polarization directions, each conductive unit adopts a rotationally symmetric design to achieve insensitivity to the polarization direction of the incident electromagnetic wave. Each conductive unit is preferably designed as a circular ring, square ring, cross, or regular hexagon, such as... Figure 3-5 Of course, other rotationally symmetric closed-loop structures can also be selected. Specifically, a double-ring nested structure is used to achieve transmission enhancement at two target frequencies, while a multi-ring nested structure is used to achieve transmission enhancement at three or more target frequencies.

[0044] There are three main ways to arrange the electromagnetic response layer: Interval arrangement: such as Figure 6 As shown, there are obvious gaps between the units. This arrangement is common in quadrilateral or annular structures, which is easy to manufacture, and the frequency response characteristics can be fine-tuned by adjusting the period P.

[0045] Closely arranged: such as Figure 7 As shown, the units are tightly joined together, for example, using a hexagonal honeycomb arrangement. This structure offers higher space utilization and structural stability, and the hexagonal structure provides a more uniform mechanical distribution, making it suitable for large-area flexible deployment. Optically, the tight arrangement also helps reduce visual interference such as moiré fringes.

[0046] Other arrangement methods include: square lattice, hexagonal lattice, quasi-periodic arrangement, or mixed partitioned arrangement.

[0047] Depending on the application requirements, different arrangement methods can be selected to balance transmission performance, optical effect, manufacturing feasibility and mechanical stability.

[0048] In practice, a transparent protective layer is superimposed on the outer surface of the electromagnetic response layer to prevent it from being mechanically scratched or oxidized, thus extending the service life of the metasurface. The protective layer can be formed using a transparent film, a transparent coating, or other highly transparent, weather-resistant materials.

[0049] In practical implementation, the transparent substrate layer is made of a highly transparent flexible material or glass, preferably PET or COC. Alternatively, the transparent substrate layer can be directly mounted on glass windows, curtain wall glass, or vehicle windows in the installation environment. The transparent substrate layer supports the electromagnetic response layer and provides necessary mechanical support and transparency. The thickness, dielectric constant, and loss parameters of the transparent substrate layer affect the electromagnetic response and require optimized design in conjunction with the target frequency band.

[0050] In specific implementations, the transparent conductive material is indium tin oxide, graphene, silver nanowires, metal mesh, or a composite transparent conductive structure (such as a combination of a metal mesh and a transparent conductive film). These materials ensure electromagnetic response while combining structural design (such as a fine-line-width metal mesh) or material properties (the high light transmittance of ITO) to ensure optical transparency.

[0051] This application also provides an application of a transparent multi-band electromagnetic anti-reflective metasurface, which is used in architectural glass, curtain wall glass, vehicle window glass or transparent partitions.

[0052] In summary, this application provides a transparent multi-band electromagnetic antireflection metasurface. The electromagnetic response layer of this application consists of periodically arrayed conductive units. When an incident electromagnetic wave of a specific frequency acts on this structure, an electromagnetic response is induced on the surface of the sub-units, causing the equivalent input impedance to match the free-space impedance. This cancels the reflection at the interface of the transparent substrate layer, achieving enhanced transmission of electromagnetic waves in a specific frequency band. The reflection of the incident electromagnetic wave at the interface of the transparent substrate layer is suppressed, and the transmission coefficient approaches 1, thus achieving lossless or low-loss transmission of electromagnetic waves, effectively solving the problem of traditional glass blocking high-frequency signals. Furthermore, this application sets multiple nested conductive units of different sizes within the sub-units of the electromagnetic response layer, allowing these nested conductive units of different sizes to form different resonant modes at different frequency positions, enabling enhanced transmission across multiple target frequency bands. To ensure optical transparency, the electromagnetic response layer uses transparent conductive materials such as indium tin oxide, graphene, or extremely fine metal mesh. To improve durability, a transparent protective layer is added to the outside of the electromagnetic response layer to prevent physical damage and environmental corrosion.

[0053] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0054] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A transparent multi-band electromagnetic antireflective metasurface, characterized in that, include: A transparent substrate layer, wherein an electromagnetic response layer is superimposed on at least one surface of the transparent substrate layer; The electromagnetic response layer includes several groups of electromagnetic response layer sub-units arranged in a periodic array. Each group of electromagnetic response layer sub-units includes multiple conductive units of different sizes nested together. The size of each conductive unit is less than half of the working wavelength. Each conductive unit is made of a transparent conductive material with electromagnetic response capability. The conductive units of different sizes can form a resonant response to electromagnetic waves of corresponding frequency bands, so that the equivalent input impedance at multiple frequency bands matches the free space impedance, thereby canceling the reflection at the interface and realizing the transmission enhancement of electromagnetic waves at multiple frequency bands.

2. The transparent multi-band electromagnetic antireflective metasurface according to claim 1, characterized in that, By adjusting the size, linewidth, ring spacing, and cell period of the conductive unit, the equivalent input impedance of the metasurface at the target frequency band is made closer to the free space impedance.

3. The transparent multi-band electromagnetic antireflective metasurface according to claim 1, characterized in that, Each of the conductive units employs a rotationally symmetric design to achieve insensitivity to the polarization direction of the incident electromagnetic wave.

4. The transparent multi-band electromagnetic antireflective metasurface according to claim 1, characterized in that, Each of the conductive units is designed as a ring, square ring, cross, or regular hexagon.

5. The transparent multi-band electromagnetic antireflective metasurface according to claim 1, characterized in that, The arrangement of the electromagnetic response layer sub-units includes periodic interval arrangement, close splicing arrangement, or square lattice, hexagonal lattice, and partitioned mixed arrangement.

6. The transparent multi-band electromagnetic antireflective metasurface according to claim 1, characterized in that, The outer surface of the electromagnetic response layer is superimposed with a transparent protective layer to prevent the electromagnetic response layer from being mechanically scratched or oxidized and corroded.

7. The transparent multi-band electromagnetic antireflective metasurface according to claim 1, characterized in that, The transparent substrate is made of a flexible material with high transparency or is glass.

8. The transparent multi-band electromagnetic antireflective metasurface according to claim 7, characterized in that, The flexible material is PET or COC.

9. The transparent multi-band electromagnetic antireflective metasurface according to claim 1, characterized in that, The transparent conductive material is indium tin oxide, graphene, silver nanowires, or metal mesh.

10. An application of a transparent multi-band electromagnetic antireflective metasurface, characterized in that, The transparent multi-band electromagnetic antireflective metasurface described in claim 9 can be used in architectural glass, curtain wall glass, vehicle window glass, or transparent partitions.

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