A variable frequency ratio metasurface absorber

Abstract

This invention relates to the field of electromagnetic shielding technology and provides a metasurface absorber with a variable frequency ratio. A first metal sheet and a second metal sheet are respectively disposed on the upper and lower surfaces of a substrate. The second metal sheet is grounded, and the first metal sheet receives electromagnetic waves and is connected to an absorption circuit to selectively absorb target electromagnetic waves. The first metal sheet has a herringbone-shaped groove, including a first main groove, a second main groove, and multiple secondary grooves. The first metal sheet is symmetrical in both the transverse and longitudinal directions. The second main groove is disposed on both sides of the first main groove and is separated from the first main groove by connecting branches. This invention isolates the first main groove and secondary grooves through the second main groove and connecting branches, reducing resonant interference between the first main groove and secondary grooves. Furthermore, when adjusting the length of the secondary grooves to adjust the corresponding target absorption frequency, interference to the absorption frequency corresponding to the first main groove can be reduced, thus lowering the design cost of absorption frequency adjustment.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic shielding technology, and in particular to a metasurface absorber with a variable frequency ratio. Background Technology

[0002] With the rapid development of information technology and wireless communication, the electromagnetic environment is becoming increasingly complex, and electromagnetic interference problems are becoming more and more severe. High-performance precision electronic equipment is particularly sensitive to electromagnetic interference. To ensure the reliability of high-performance precision electronic equipment, electromagnetic shielding design is required.

[0003] Among them, metasurface technology, by precisely designing its structural units at the subwavelength scale, can regulate various electromagnetic phenomena such as reflection, refraction, and transmission of electromagnetic waves. Compared with traditional electromagnetic shielding materials such as metal shielding materials and ferrite materials, metasurface absorbers have higher absorption efficiency and also have advantages such as being lightweight, thin, low-cost, and highly adjustable. They have shown broad application prospects in fields such as electromagnetic shielding, radar stealth, satellite communication, and autonomous driving.

[0004] However, the structural parameters of existing metasurface absorbers related to the resonant frequency are relatively fixed. When it is necessary to adjust the parameters to adapt to the absorption requirements of electromagnetic waves of different frequencies, it is often necessary to redesign all structural parameters, resulting in high design costs for compatibility. Summary of the Invention

[0005] Based on this, the purpose of the present invention is to provide a metasurface absorber with a variable frequency ratio to solve the problem that the absorption frequency of existing metasurface absorbers lacks adjustability, which increases the cost of compatibility design.

[0006] This invention provides a variable frequency ratio metasurface absorber, comprising: a substrate, and a first metal sheet and a second metal sheet disposed on the upper and lower surfaces of the substrate, wherein...

[0007] The second metal sheet is used for grounding, and the first metal sheet is connected to the absorption circuit to receive electromagnetic waves and selectively absorb target electromagnetic waves through the absorption circuit.

[0008] The first metal sheet is provided with a fishbone-shaped groove, which includes a first main groove, a second main groove and a plurality of secondary grooves. The first metal sheet is symmetrical in both the transverse and longitudinal directions.

[0009] The second main trench is disposed on both sides of the first main trench and is separated from the first main trench by connecting branches, which are connected to the absorption circuit.

[0010] The length of the secondary trench corresponds to the frequency of the target electromagnetic wave, and the longer the secondary trench, the lower the frequency.

[0011] Optionally, the length of the second main trench is less than the length of the first main trench, and the extension area of ​​the second main trench is greater than the setting area of ​​the secondary trench.

[0012] Optionally, the first main trench, the second main trench, and the secondary trench are all rectangular.

[0013] Optionally, the connecting stub extends towards the center of the first main trench along its extension direction, and an L-shaped resonant stub is provided at the end of the connecting stub.

[0014] The bottom edge of the resonant stub is perpendicular to the extension direction of the first main groove, and the long side of the resonant stub is connected to the first end of the bottom edge, which is the end away from the first main groove.

[0015] The four resonant stubs surround a terminal region, and a connection terminal is provided in the terminal region. The first metal sheet is connected to the absorption circuit through the connection terminal, and the center of the four sides of the terminal region is open.

[0016] Optionally, a coupling piece is further provided in the terminal area, wherein,

[0017] The coupling plate is perpendicular to the extension direction of the first main groove and coaxial with the central axis of the first main groove.

[0018] Two coupling plates are provided, and the sides of the plates closest to each other are aligned with the ends of the long sides of the corresponding resonant stubs.

[0019] The two ends of the coupling plate are respectively connected to the second end of the bottom edge of the corresponding resonant stub through a first connection terminal, and the middle node of the two coupling plates is connected through a second connection terminal.

[0020] Optionally, one of the first connection terminals is grounded through a resonant circuit, and the second connection terminal and the other first connection terminals are each grounded through a diode.

[0021] Optionally, the resonant circuit includes at least one of an RC parallel resonant circuit and an RL series resonant circuit.

[0022] Optionally, the second metal sheet has the same size as the substrate, and each edge of the metal sheet overlaps with each edge of the substrate.

[0023] Optionally, the first main groove is parallel to the transverse direction of the first metal sheet, wherein,

[0024] The first metal sheet has a lateral length that is less than the lateral length of the substrate, and is centered along the lateral direction of the substrate;

[0025] The longitudinal length of the first metal sheet is the same as the longitudinal length of the substrate, and it is centered along the longitudinal direction of the substrate.

[0026] Optionally, the metasurface absorber array is provided with multiple arrays.

[0027] The variable frequency ratio metasurface absorber provided by this invention includes a substrate, and a first metal sheet and a second metal sheet disposed on the upper and lower surfaces of the substrate. The second metal sheet is grounded, and the first metal sheet is connected to an absorption circuit to receive electromagnetic waves and selectively absorb target electromagnetic waves through the absorption circuit. The first metal sheet has a herringbone-shaped groove, including a first main groove, a second main groove, and multiple secondary grooves. The first metal sheet is symmetrical in both the transverse and longitudinal directions. The second main groove is disposed on both sides of the first main groove and separated from it by connecting branches. The connecting branches are connected to the absorption circuit, transferring the electromagnetic wave energy received by the second metal sheet to the absorption circuit, which then releases the energy to ground. This invention isolates the first main groove and secondary grooves through the second main groove and connecting branches, reducing resonant interference between them. Furthermore, when adjusting the length of the secondary grooves to adjust the corresponding target absorption frequency, interference to the absorption frequency corresponding to the first main groove is reduced, thus ensuring the reliability of multiple absorption frequencies, reducing the design cost of absorption frequency adjustment, and improving the applicability of the metasurface absorber. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the upper surface structure of the variable frequency ratio metasurface absorber in an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the array layout of the variable frequency ratio metasurface absorber in an embodiment of the present invention;

[0030] Figure 3 This is a simulated scattering parameter curve of the variable frequency ratio metasurface absorber in the embodiment of the present invention;

[0031] Figure 4 The simulated scattering parameter curves are for sub-trenches of different lengths of the variable frequency ratio metasurface absorber in the embodiments of the present invention.

[0032] Figure 5 This is a schematic diagram of the first absorption circuit of the variable frequency ratio metasurface absorber in an embodiment of the present invention.

[0033] Figure 6 This is a graph showing the absorption characteristics of the first absorption circuit of the variable frequency ratio metasurface absorber in an embodiment of the present invention.

[0034] Figure 7This is a schematic diagram of the second absorption circuit of the variable frequency ratio metasurface absorber in an embodiment of the present invention;

[0035] Figure 8 This is a graph showing the absorption characteristics of the second absorption circuit of the variable frequency ratio metasurface absorber in an embodiment of the present invention.

[0036] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0037] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of the invention are illustrated in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0038] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0039] 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 invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0040] To address the lack of adjustable absorption frequency in existing metasurface absorbers, which increases compatibility design costs, this invention provides a variable frequency ratio metasurface absorber. A first metal sheet and a second metal sheet are respectively disposed on the upper and lower surfaces of a substrate. The second metal sheet is grounded, and the first metal sheet is connected to an absorption circuit to receive electromagnetic waves and selectively absorb target electromagnetic waves. The first metal sheet has a herringbone-shaped groove, including a first main groove, a second main groove, and multiple secondary grooves. The first metal sheet is symmetrical in both the horizontal and vertical directions. The second main groove is located on both sides of the first main groove and is separated from it by connecting branches. By isolating the first main groove and secondary grooves through the second main groove and connecting branches, the resonant interference between the first main groove and secondary grooves can be reduced. Therefore, when adjusting the length of the secondary grooves to adjust the corresponding target absorption frequency, interference to the absorption frequency corresponding to the first main groove can be reduced, thus lowering the design cost of absorption frequency adjustment.

[0041] Specifically, such as Figure 1 As shown, a first metal sheet 20 is disposed on the upper surface of the substrate 10, and a second metal sheet (not shown) is disposed on the lower surface. The first metal sheet 20 is used to receive electromagnetic waves, and the second metal sheet is used for grounding. The substrate 10 is the same size as the substrate 10, and the edges of each side overlap with the edges of the substrate 10 to ensure grounding effect. An absorption circuit can be disposed in the substrate 10 and connected to the first metal sheet 20 and the second metal sheet to ground the electromagnetic wave energy received by the first metal sheet 20, thereby achieving energy absorption.

[0042] To provide multi-frequency absorption, in this embodiment, the first metal sheet 20 is provided with a fishbone-shaped groove, which includes a first main groove 211, a second main groove 212 and a plurality of secondary grooves 213. The first metal sheet 20 is symmetrical in both the horizontal and vertical directions.

[0043] The first main groove 211, the second main groove 212, and the multiple secondary grooves 213 are all rectangular grooves, which match the periodic characteristics of electromagnetic waves. The parameters are easy to design, and all the sides and corners are right angles, which facilitates precise processing.

[0044] The first metal sheet 20 has a lateral length less than the lateral length of the substrate 10 and is centered along the lateral direction of the substrate 10. The first metal sheet 20 has a longitudinal length the same as the longitudinal length of the substrate 10 and is centered along the longitudinal direction of the substrate 10, with the upper and lower sides overlapping.

[0045] Multiple metasurface absorbers 100 can be arrayed, such as Figure 2 As shown, the specific array size can be selected according to the specific dimensions of the actual absorption surface. In the array, the edges of the metasurface absorbers 100 are attached and spliced ​​together.

[0046] The first main groove 211 connects both sides of the first metal sheet 20 and is parallel to the transverse direction of the first metal sheet 20, dividing the first metal sheet 20 into two symmetrical parts; the second main groove 212 is arranged parallel to both sides of the first main groove 211 and is separated from the first main groove 211 by connecting branches, which are connected to the absorption circuit; the secondary groove 213 is perpendicular to the first main groove 211, and there are multiple grooves arranged at even intervals.

[0047] The length of the first main trench 211 corresponds to the first resonant frequency, and the length of the secondary trench 213 corresponds to the second resonant frequency, so as to receive electromagnetic waves at the first and second resonant frequencies. The absorption frequency of the absorption circuit is matched with it, so as to realize the absorption of electromagnetic waves at the first and second resonant frequencies.

[0048] In this specific example, substrate 10 is a three-layer board made of Rogers 3010 material, with dimensions of 22mm × 22mm, a relative permittivity εr of 10.2, a loss tangent of 0.0035, and a single-layer thickness of 1.28mm. The first metal sheet 20 and the second metal sheet are 20mm × 10.4mm copper sheets with a thickness of 17µm. The conductivity as a function of frequency is σ = 5.8 × 10^7 S / m (Siemens per meter). The simulated scattering parameter curve is shown in the figure. Figure 3 As shown, the S-parameters (scattering parameters) at the first and second resonant frequencies are both less than -10dB, indicating that the reflection coefficient is only 0.1. 10% of the input signal power is reflected, and 90% of the signal power is transmitted to ground or absorbed by the absorption circuit. The signal loss is small, the transmission performance is good, and it has a strong waveform selective absorption capability.

[0049] The first main trench 211 connects both sides of the first metal sheet 20, has a width of 1.2 mm, and a relatively fixed length. Its first resonant frequency is not easily adjusted. The secondary trench 213 has dimensions of 3.5 mm × 0.83 mm, smaller than half the size of the first metal sheet 20, and its length is adjustable, corresponding to an adjustable second resonant frequency. The size of the first main trench 211 is larger than the size of the secondary trench, corresponding to a wavelength at the first resonant frequency that is greater than the wavelength at the second resonant frequency, and a first resonant frequency that is less than the second resonant frequency.

[0050] The first main groove 211 and the secondary groove 213 are perpendicular and separated by connecting branches, which can effectively reduce the coupling interference between the first main groove 211 and the secondary groove 213, and provide convenience for the adjustable design of the second resonant frequency.

[0051] Specifically, such as Figure 4 The figure shows the simulated scattering parameter curves for the length l of the secondary trench 213 at 3.0 mm, 3.5 mm, and 4.0 mm. With the adjustment of the length of the secondary trench 213, the change in the first resonant frequency is small, and the S-parameters are all less than -10 dB, ensuring the absorption efficiency at the first resonant frequency. With the increase of the length of the secondary trench 213, the second resonant frequency decreases, and the absorption efficiency gradually increases.

[0052] Specifically, the second main groove 212 has dimensions of 15.8mm × 0.4mm, and its length is less than that of the first main groove 211. The extension area of ​​the second main groove 212 is greater than the setting area of ​​the secondary groove 213, and the spacing and width of the secondary grooves 213 are consistent.

[0053] To facilitate connection with the absorption circuit, in this embodiment, the connecting stub extends towards the center of the first main groove 211 along the extension direction of the first main groove 211. An L-shaped resonant stub 22 is provided at the end of the connecting stub. The short side of the L-shaped resonant stub 22 has a length of 0.9 mm, a long side length of 2.9 mm, and a width of 0.3 mm. The bottom edge of the resonant stub 22 is perpendicular to the extension direction of the first main groove 211. The long side of the resonant stub is connected to the first end of the bottom edge, which is the end away from the first main groove 211. The second end of the bottom edge is used to connect with the connecting terminal 30, so that the path from the connection point of the connecting terminal 30 and the connecting stub to the two ends of the connecting stub is close.

[0054] Four L-shaped resonant stubs 22 surround a terminal area, in which a connecting terminal 30 is provided. The first metal plate 20 is connected to the absorption circuit through the connecting terminal 30. The center of each of the four sides of the terminal area is open, and the electrical signal generated by resonance is input to the absorption circuit from four directions. The terminal area being surrounded by resonant stubs 22 also improves the electromagnetic isolation of the terminal area and avoids resonant interference in the terminal area.

[0055] The connection terminal 30 includes multiple electrodes (first electrode 31 to fifth electrode 35), and the electrodes can be selected from gold, silver, transparent conductive oxide, graphene, etc., to avoid resonance interference to the first metal sheet 20.

[0056] To improve the resonance effect, a coupling piece 23 with dimensions of 1.2mm × 0.4mm is also provided in the terminal area. The coupling piece 23 is made of the same material as the first metal piece 20, is perpendicular to the extension direction of the first main groove 211, and is coaxial with the central axis of the first main groove 211. The coupling piece 23 couples with the resonant stub 22 to improve the resonance effect, such as... Figure 4 As shown, when adjusting the second resonant frequency, the stability of the first resonant frequency can be effectively guaranteed, and the deviation of the first resonant frequency can be reduced.

[0057] Two coupling plates 23 are provided, and their sides close to each other are aligned with the ends of the long sides of the corresponding resonant stubs 22. The two ends of the coupling plates 23 are respectively connected to the second end of the bottom side of the corresponding resonant stubs 22 through a first connection terminal (including a first electrode 31, a second electrode 32, a fourth electrode 34, and a fifth electrode 35). The middle node of the two coupling plates 23 is connected through a second connection terminal (a third electrode 33).

[0058] The four electrodes of the first connection terminal are symmetrical. One electrode of the first connection terminal is grounded through a resonant circuit. The electrodes of the second connection terminal and the other first connection terminals are grounded through a diode. By selecting the resonant circuit, the absorption rate of continuous waves and pulse waves can be adjusted.

[0059] Specifically, in one instance, such as Figure 5 and Figure 6 As shown, the resonant circuit includes an RC parallel resonant circuit. The capacitor of the RC parallel resonant circuit is 1nF and the resistor is 10KΩ. Near the two resonant frequencies of 1.58GHz and 2.77GHz, its absorption rate for pulse waves is higher than its absorption rate for continuous waves.

[0060] In another instance, such as Figure 7 and Figure 8 As shown, the resonant circuit includes an RL series resonant circuit. The inductor of the RL series resonant circuit is 100µH and the resistor is 5.5Ω. Near the two resonant frequencies of 1.58GHz and 2.77GHz, its absorption rate for continuous waves is higher than its absorption rate for pulse waves.

[0061] The variable frequency ratio metasurface absorber provided by this invention has a first metal sheet and a second metal sheet respectively disposed on the upper and lower surfaces of a substrate. The second metal sheet is grounded, and the first metal sheet is connected to an absorption circuit to receive electromagnetic waves and selectively absorb target electromagnetic waves through the absorption circuit. The first metal sheet has a herringbone-shaped groove, including a first main groove, a second main groove, and multiple secondary grooves. The first metal sheet is symmetrical in both the horizontal and vertical directions. The second main groove is disposed on both sides of the first main groove and separated from it by connecting branches. The connecting branches are connected to the absorption circuit, transferring the electromagnetic wave energy received by the second metal sheet to the absorption circuit, which then releases the energy to ground. By isolating the first main groove and secondary grooves through the second main groove and connecting branches, the resonant interference between the first main groove and secondary grooves can be reduced. Furthermore, when adjusting the length of the secondary grooves to adjust the corresponding target absorption frequency, interference to the absorption frequency corresponding to the first main groove can be reduced, thereby ensuring the reliability of multiple absorption frequencies, reducing the design cost of absorption frequency adjustment, and improving the applicability of the metasurface absorber.

[0062] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0063] The embodiments described above are merely illustrative of several specific implementations of the present invention, and while the descriptions are detailed, they should not be construed as limiting the scope of protection of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A metasurface absorber with a variable frequency ratio, characterized in that, include: A substrate, and a first metal sheet and a second metal sheet disposed on the upper and lower surfaces of the substrate, wherein, The second metal sheet is used for grounding, and the first metal sheet is connected to the absorption circuit to receive electromagnetic waves and selectively absorb target electromagnetic waves through the absorption circuit. The first metal sheet is provided with a fishbone-shaped groove, which includes a first main groove, a second main groove and a plurality of secondary grooves. The first metal sheet is symmetrical in both the transverse and longitudinal directions. The second main trench is disposed on both sides of the first main trench and is separated from the first main trench by connecting branches, which are connected to the absorption circuit. The length of the sub-groove corresponds to the frequency of the target electromagnetic wave, and the longer the sub-groove, the lower the frequency. Wherein, the connecting branch extends towards the center of the first main groove along the extension direction of the first main groove, and an L-shaped resonant branch is provided at the end of the connecting branch. The bottom edge of the resonant branch is perpendicular to the extension direction of the first main groove, and the long side of the resonant branch is connected to the first end of the bottom edge, which is the end away from the first main groove. The four resonant stubs surround a terminal area, and a connection terminal is provided in the terminal area. The first metal sheet is connected to the absorption circuit through the connection terminal, and the center of the four sides of the terminal area is open. A coupling piece is also provided in the terminal area. The coupling piece is perpendicular to the extension direction of the first main groove and coaxial with the central axis of the first main groove. Two coupling plates are provided, and the sides of the plates closest to each other are aligned with the ends of the long sides of the corresponding resonant stubs. The two ends of the coupling plate are respectively connected to the second end of the bottom edge of the corresponding resonant stub through a first connection terminal, and the middle node of the two coupling plates is connected through a second connection terminal.

2. The variable frequency ratio metasurface absorber of claim 1, wherein, The length of the second main trench is less than the length of the first main trench, and the extension area of ​​the second main trench is greater than the setting area of ​​the secondary trench.

3. The variable frequency ratio metasurface absorber of claim 1, wherein, The first main trench, the second main trench, and the secondary trench are all rectangular.

4. The variable-frequency-ratio metasurface absorber of claim 1, wherein, One of the first connection terminals is grounded through a resonant circuit, and the second connection terminal and the other first connection terminals are each grounded through a diode.

5. The variable-frequency-ratio metasurface absorber of claim 4, wherein, The resonant circuit includes at least one of an RC parallel resonant circuit and an RL series resonant circuit.

6. The variable frequency ratio metasurface absorber according to claim 1, characterized in that, The second metal sheet has the same size as the substrate, and each edge of the metal sheet overlaps with the edges of the substrate.

7. The variable frequency ratio metasurface absorber according to claim 1, characterized in that, The first main groove is parallel to the transverse direction of the first metal sheet, wherein, The first metal sheet has a lateral length that is less than the lateral length of the substrate, and is centered along the lateral direction of the substrate; The longitudinal length of the first metal sheet is the same as the longitudinal length of the substrate, and it is centered along the longitudinal direction of the substrate.

8. The variable-frequency-ratio metasurface absorber of claim 1, wherein, The array of metasurface absorbers is provided in multiple forms.

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