Metasurface-based electromagnetic shielding device, antenna and electronic device

Abstract

This invention discloses an electromagnetic protection device, antenna, and electronic device based on a metasurface. By integrating a scattering-modulated metasurface structure and an energy-selective surface, the energy-selective surface can adaptively protect against high-power electromagnetic waves. The scattering-modulated metasurface located above the energy-selective surface can transmit incident electromagnetic waves in the communication band while absorbing incident electromagnetic waves in the target absorption band and reflected electromagnetic waves from the energy-selective surface. This ensures the stability of the communication link for UAVs in complex electromagnetic environments and low insertion loss transmission in the communication band. It also provides high-energy electromagnetic wave protection and improves the stealth performance of UAVs, thus meeting the electromagnetic protection requirements of UAVs in complex electromagnetic environments.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic metasurface technology, and in particular to electromagnetic protection devices, antennas and electronic devices based on metasurfaces. Background Technology

[0002] With the rapid development of modern communication technology, antennas integrating wideband, multi-frequency, and dynamic frequency reconfiguration capabilities are gradually being applied in engineering practice to meet the working requirements of complex electromagnetic environments. Metasurfaces are two-dimensional metamaterials that address the problems of narrow bandwidth, high loss, and high processing costs of three-dimensional materials in antenna radome design through a compromise. Among them, active frequency selective surfaces, as a periodic electromagnetic structure, have been widely used in electromagnetic shielding, microwave communication, electromagnetic stealth, and other application scenarios due to their frequency selectivity for electromagnetic waves of different frequencies. In electronic devices such as drones and communication equipment, they can achieve electromagnetic protection and communication compatibility, reducing the impact of external electromagnetic interference on the normal operation of electronic devices.

[0003] Existing metasurface-based electromagnetic protection devices suffer from low functional integration and limited electromagnetic protection capabilities. For drones, which heavily rely on stable communication links and need to cope with various interferences in complex electromagnetic environments, as well as possess a certain degree of stealth capability in some working scenarios, existing metasurface-based electromagnetic protection devices are insufficient to meet the electromagnetic protection needs of drones in complex electromagnetic environments. Summary of the Invention

[0004] This invention provides an electromagnetic protection device, antenna, and electronic device based on metasurfaces to solve the technical problems of low functional integration and single electromagnetic protection function in existing metasurface-based electromagnetic protection devices.

[0005] To address the aforementioned technical problems, a first aspect of this invention provides an electromagnetic protection device based on a metasurface, comprising a scattering-modulated metasurface structure and an energy-selective surface; the scattering-modulated metasurface structure is disposed above the energy-selective surface; the scattering-modulated metasurface structure is used to transmit incident electromagnetic waves in the communication band and absorb incident electromagnetic waves in the target absorption band and reflected electromagnetic waves from the energy-selective surface.

[0006] As a preferred embodiment, the scattering-controlled metasurface structure includes a first dielectric substrate, an absorbing layer, an air dielectric layer, a frequency selective surface, and a second dielectric substrate; the absorbing layer is disposed at the bottom of the first dielectric substrate, the frequency selective surface is disposed at the top of the second dielectric substrate, and the air dielectric layer is disposed between the absorbing layer and the frequency selective surface.

[0007] As a preferred embodiment, the absorbing layer includes a plurality of periodically arranged and rotationally symmetrical first metal units; each first metal unit includes a plurality of metal patch structures, the metal patch structure being formed by connecting a plurality of rectangular metal patches, two of the rectangular metal patches being perpendicular to each other, and at least one resistor being loaded on the rectangular metal patch; wherein, the loading position of the resistor is determined based on the electric field distribution of the electromagnetic wave in the target absorbing frequency band on the rectangular metal patch.

[0008] As a preferred embodiment, the frequency selective surface includes a plurality of periodically arranged second metal units; the second metal unit includes a center-connected metal patch with a tortuous metal segment; at least one resistor is loaded on the center-connected metal patch, and a first varactor diode and a second varactor diode are connected within the gap of the tortuous metal segment; wherein, the loading position of the resistor is determined based on the electric field distribution of the electromagnetic wave in the target absorbing frequency band on the center-connected metal patch.

[0009] As a preferred embodiment, the energy selection surface includes a plurality of periodically arranged metal patch units, each metal patch unit having four arc-shaped defect openings on its outer side and a circular defect area inside the metal patch unit; a diode is disposed in the gap between two adjacent metal patch units so that the diode is connected in parallel with the equivalent capacitance corresponding to the gap in which it is located.

[0010] As a preferred embodiment, the device further includes a third dielectric substrate, and the scattering-modulated metasurface structure further includes a bias network layer; the third dielectric substrate is disposed at the bottom of the second dielectric substrate, the energy selective surface is disposed at the bottom of the third dielectric substrate, and the bias network layer is disposed between the second dielectric substrate and the third dielectric substrate; The bias network layer is used to output a reverse regulation voltage to the first varactor diode and the second varactor diode to change the capacitance value of the first varactor diode and the second varactor diode, so that the communication bandpass changes with the change of the capacitance value of the first varactor diode and the second varactor diode.

[0011] As a preferred embodiment, the bias network layer includes a plurality of periodically arranged third metal units; the third metal unit includes a rectangular metal patch corresponding to the second metal unit and a metal microstrip conductor disposed within the rectangular metal patch; A through-hole penetrating the second dielectric substrate is provided between the first varactor diode and the second varactor diode. A metal connector is provided in the through-hole. One end of the metal connector is connected to the negative terminal of the first varactor diode and the negative terminal of the second varactor diode, respectively. The other end of the metal connector is connected to one end of the metal microstrip wire, and the other end of the metal microstrip wire is connected to the rectangular frame metal patch.

[0012] As a preferred embodiment, the center-connected metal patch is formed by bending at least one arm of the Jerusalem cross-shaped metal patch so that the frequency selection surface has at least one band-stop resonant frequency.

[0013] A second aspect of the present invention provides an antenna, the antenna comprising an electromagnetic protection device based on a metasurface as described in any of the first aspects.

[0014] A third aspect of the present invention provides an electronic device, the electronic device including the antenna as described in the second aspect.

[0015] Compared to existing technologies, the beneficial effects of this invention are that by integrating a scattering-modulated metasurface structure and an energy-selective surface, the energy-selective surface can be used to adaptively protect against high-power electromagnetic waves. The scattering-modulated metasurface located above the energy-selective surface can transmit incident electromagnetic waves in the communication band while absorbing incident electromagnetic waves in the target absorption band and reflected electromagnetic waves from the energy-selective surface. This ensures the stability of the communication link for UAVs in complex electromagnetic environments and low insertion loss transmission in the communication band. It also enables high-energy electromagnetic wave protection and improves the stealth performance of UAVs, thereby meeting the electromagnetic protection requirements of UAVs in complex electromagnetic environments. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the layered structure of the electromagnetic protection device in an embodiment of the present invention; Figure 2 This is a schematic diagram of the overall structure of the electromagnetic protection device in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the first metal unit in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of the second metal unit in an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of the energy selective surface in an embodiment of the present invention; Figure 6 This is a schematic diagram of the structure of the third metal unit in an embodiment of the present invention; Figure 7This is a schematic diagram of some dimensional parameters of the electromagnetic protection device in an embodiment of the present invention; Figure 8 This is a graph showing the changes in the communication band frequency, the absorption band, and the shielding effectiveness in embodiments of the present invention. The components are as follows: 1. First dielectric substrate; 2. Absorbing layer; 201. Metal patch structure; 3. Air dielectric layer; 4. Frequency selective surface; 401. First varactor diode; 402. Second varactor diode; 403. Center-connected metal patch; 5. Second dielectric substrate; 6. Bias network layer; 601. Rectangular frame metal patch; 602. Metal microstrip wire; 7. Third dielectric substrate; 8. Energy selective surface; 801. Metal patch unit; 802. Arc-shaped defect opening; 803. Circular defect area; 804. Diode; 9. Metal connector; 10. Resistor. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0018] In the description of this application, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," "third," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0019] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. The terms "vertical," "horizontal," "left," "right," "upper," "lower," and similar expressions used in this application are for illustrative purposes only and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention. The term "and / or" used in this application includes any and all combinations of one or more of the related listed items. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0020] In the description of this application, it should be noted that, unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing specific embodiments only and is not intended to limit the invention. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0021] Please see Figure 1 and Figure 2 The first aspect of the present invention provides an electromagnetic protection device based on a metasurface, including a scattering-controlled metasurface structure and an energy-selective surface 8; the scattering-controlled metasurface structure is disposed above the energy-selective surface 8; the scattering-controlled metasurface structure is used to transmit incident electromagnetic waves in the communication band and absorb incident electromagnetic waves in the target absorption band and reflected electromagnetic waves from the energy-selective surface 8.

[0022] It is worth noting that in the actual working environment of a drone, in addition to receiving communication signals in the communication band (such as the commonly used 2.4GHz and 5.8GHz frequency bands), it is also necessary to avoid being detected by detection signals in non-communication bands. For example, it is necessary to avoid being detected by detection signals in the X-band (8GHz~12GHz) to achieve the purpose of stealth. Therefore, the electromagnetic protection device in this embodiment includes a scattering-controlled metasurface structure and an energy-selective surface 8. It can be understood that in the scattering problem, the metasurface can be used to control the transmitted electromagnetic waves and the reflected electromagnetic waves. That is, when the electromagnetic wave is incident on the electromagnetic metasurface, the amplitude, direction, polarization and waveform of the transmitted beam and the reflected beam are controllable. In this embodiment, the scattering-controlled metasurface structure is specifically designed as a periodically arranged layered structure. The band-stop resonant frequency of the scattering-controlled metasurface structure can be adjusted through the design of the metal patch shapes on the metasurface and the interlayer equivalent capacitance coupling. The band-stop resonant frequency determines the communication bandpass. That is, at this band-stop resonant frequency, the scattering-controlled metasurface structure exhibits band-stop characteristics. When the frequency of the incident electromagnetic wave matches the band-stop resonant frequency, all the electromagnetic energy of the incident electromagnetic wave is converted into the kinetic energy of electron oscillations. At this time, the incident electromagnetic wave does not propagate, and a passband is formed on both sides of the stopband corresponding to the band-stop resonant frequency. Therefore, a specific communication bandpass can be obtained by adjusting the band-stop resonant frequency. The frequency band ensures that communication signals can be transmitted. Simultaneously, for detection signals outside the communication band, this embodiment determines the target absorbing frequency band based on the frequency band involved in the detection signal to be absorbed. Loss-inducing elements are loaded onto the electric field distribution of the incident electromagnetic wave on the scattering-controlled metasurface structure within the target absorbing frequency band. These loss-inducing elements dissipate the energy of the incident electromagnetic wave within the target absorbing frequency band, thereby absorbing the electromagnetic wave within the target absorbing frequency band. This reduces the electromagnetic wave reflection intensity within that band, improving the stealth capability of electronic equipment in detection frequency bands other than the communication band, while avoiding significant impact of the absorbing function on the transmission of incident electromagnetic wave signals in the communication band. In one embodiment, considering commonly used communication signal bands such as 2.4 GHz and 5.8 GHz, the communication band can be located within the frequency selection range of 2.4 GHz to 7.0 GHz, while the target absorbing frequency band can cover 7.5 GHz to 15 GHz.

[0023] Furthermore, the energy selective surface 8 possesses key advantages such as high-power protection, self-adaptation, and fast response, with its core mechanism being field-to-impedance transformation. It's worth noting that the energy selective surface 8, based on the frequency selective surface, incorporates switching components, such as PIN (Positive-Intrinsic-Negative) diodes 804 and Schottky barrier diodes 804, at the gaps or connections between the metal patches. These components are triggered by the electric field constructed at the metasurface by the incident electromagnetic wave. When the surface electric field strength difference formed by the incident electromagnetic wave exceeds the component's conduction threshold, it automatically switches states, causing the energy selective surface 8 to exhibit different frequency response characteristics. This effectively protects against high-power electromagnetic waves, such as HPM (High-Power Microwave). In its protected state, the energy selective surface 8 allows lower-power signals to pass normally, while higher-power signals are shielded. It is worth noting that when the energy selective surface 8 is in its unprotected state, i.e., when the described switching element is in the off state, it is equivalent to a frequency selective surface. Therefore, a communication band can also be set according to the design of the metal patch shape and the interlayer equivalent capacitance coupling. The communication band can be the same as or different from the communication band of the scattering-controlled metasurface structure, as long as the communication signal can be transmitted smoothly. For example, the transmission of commonly used frequency band communication signals of 2.4 GHz and 5.8 GHz can be guaranteed. This embodiment does not make specific limitations here, so as to achieve secondary frequency screening of incident electromagnetic waves and ensure low insertion loss transmission of incident electromagnetic wave signals in the communication band. For incident electromagnetic waves in the non-communication band (i.e., stopband) of the energy selective surface 8, they are reflected. The reflected electromagnetic waves are reflected multiple times between the scattering-controlled metasurface structure and the energy selective surface 8, thereby inducing the absorption resonance of the scattering-controlled metasurface structure to absorb the reflected electromagnetic waves, further ensuring the absorption and attenuation of the probe electromagnetic waves.

[0024] The electromagnetic protection device based on metasurface provided in this invention integrates a scattering-modulated metasurface structure and an energy-selective surface 8. The energy-selective surface 8 can adaptively protect against high-power electromagnetic waves. The scattering-modulated metasurface located above the energy-selective surface 8 can transmit incident electromagnetic waves in the communication band while absorbing incident electromagnetic waves in the target absorption band and reflected electromagnetic waves from the energy-selective surface 8. This ensures the stability of the communication link for UAVs in complex electromagnetic environments and low insertion loss transmission in the communication band. It also provides high-energy electromagnetic wave protection and improves the stealth performance of UAVs, thus meeting the electromagnetic protection requirements of UAVs in complex electromagnetic environments.

[0025] As a preferred embodiment, the scattering-controlled metasurface structure includes a first dielectric substrate 1, an absorbing layer 2, an air dielectric layer 3, a frequency selective surface 4, and a second dielectric substrate 5; the absorbing layer 2 is disposed at the bottom of the first dielectric substrate 1, the frequency selective surface 4 is disposed at the top of the second dielectric substrate 5, and the air dielectric layer 3 is disposed between the absorbing layer 2 and the frequency selective surface 4.

[0026] Specifically, the scattering-controlled metasurface structure in this embodiment further includes a first dielectric substrate 1, an absorbing layer 2, an air dielectric layer 3, a frequency selective surface 4, and a second dielectric substrate 5. The thickness of the air dielectric layer 3 determines the interlayer coupling capacitance between the absorbing layer 2 and the frequency selective surface 4, thereby enabling adjustment of the band-stop resonant frequency. This allows for designs that are not limited to the metal structure within the frequency selective surface 4. When electronic devices have miniaturization requirements for electromagnetic protection devices, the area of ​​the frequency selective surface 4 may be limited. Therefore, this band-stop resonant frequency adjustment method, which adjusts the interlayer coupling capacitance by controlling the thickness of the air dielectric layer 3, can effectively ensure the miniaturization effect.

[0027] Furthermore, in this embodiment, both the absorbing layer 2 and the frequency selective surface 4 are provided with metal patches to form a resonant structure. Since the size of the metal patches (such as length, width, and thickness) affects the magnitude of their equivalent inductance, and the gap size between the metal patches affects the equivalent capacitance of the overall structure, the overall impedance of the absorbing layer 2 can be adjusted by adjusting the equivalent inductance and equivalent capacitance through the design of the metal patch structure 201 in the absorbing layer 2, thereby forming a specific band-stop resonant frequency. In addition, a resistor 10 is also loaded in the absorbing layer 2 as a loss element, which can dissipate the surface current formed by the incident electromagnetic wave in the target absorption frequency band as heat, thereby achieving efficient absorption of the incident electromagnetic wave in the target absorption frequency band and reducing the electromagnetic wave reflection intensity. Similarly, the impedance of the frequency selective surface 4 is adjusted through the design of the metal patch structure 201, thereby forming a specific communication bandpass with the interlayer coupling capacitor between it and the absorbing layer 2.

[0028] As a preferred embodiment, the absorbing layer 2 includes a plurality of periodically arranged and rotationally symmetrical first metal units; the first metal unit includes a plurality of metal patch structures 201, the metal patch structure 201 being formed by connecting a plurality of rectangular metal patches, two of the rectangular metal patches being perpendicular to each other, and at least one resistor 10 being loaded on the rectangular metal patch; wherein, the loading position of the resistor is determined based on the electric field distribution of the electromagnetic wave in the target absorbing frequency band on the rectangular metal patch.

[0029] Please see Figure 3In this embodiment, the first metal unit of the absorbing layer 2 is a rotationally symmetric metal structure, and the metal patch structure 201 in the first metal unit is composed of multiple rectangular metal patches connected together. Two interconnected rectangular metal patches are perpendicular to each other, thereby achieving polarization insensitivity of the absorbing layer 2 and exhibiting consistent electromagnetic response characteristics to incident electromagnetic waves with different polarization directions. Furthermore, a resistor 10 is loaded onto the rectangular metal patch. It is understood that the electromagnetic waves in the target absorption frequency band in this embodiment include incident electromagnetic waves in the target absorption frequency band and reflected electromagnetic waves from the energy selection surface 8. When electromagnetic waves of different frequencies irradiate the metal patch structure 201, different electric field distributions are formed on the metal patch structure 201, resulting in surface currents at different positions of the metal patch structure 201. Therefore, the loading position of the resistor 10 can be determined by first obtaining the electric field distribution of the metal patch structure 201 that matches the target absorption frequency band, and then selecting the position with the higher surface current density as the resistor 10. At the loading position 0, the surface current density formed by electromagnetic wave irradiation within the target absorption frequency band is relatively high. Therefore, the resistor 10 placed here can effectively convert the surface current formed by the incident electromagnetic wave within the target absorption frequency band into heat for dissipation, ensuring the absorption effect. The resistance value of the resistor 10 can be determined by the overall structural impedance characteristics required after confirming the loading position of the resistor 10, thereby achieving specific absorption characteristics. This embodiment does not make specific limitations here. The number of loaded resistors 10 needs to consider the rotational symmetry of the first metal unit and the overall orthogonality of the first metal unit. This embodiment does not make specific limitations here. At the same time, setting multiple rectangular metal patches can effectively capture electromagnetic waves within the target absorption frequency band and form corresponding surface currents, thereby utilizing multiple resistors 10 to effectively dissipate the surface currents and improve the absorption effect.

[0030] As a preferred embodiment, the frequency selection surface 4 includes a plurality of periodically arranged second metal units; the second metal unit includes a center-connected metal patch 403 with a tortuous metal segment; at least one resistor 10 is loaded on the center-connected metal patch 403, and a first varactor diode 401 and a second varactor diode 402 are connected within the gap of the tortuous metal segment; wherein, the loading position of the resistor 10 is determined based on the electric field distribution of the electromagnetic wave in the target absorption frequency band on the center-connected metal patch 403.

[0031] Please see Figure 4In this embodiment, the second metal unit included in the frequency selective surface 4 includes a centrally connected metal patch 403 with a zigzag metal segment. It is understood that the zigzag metal segment is longer than the vertical metal segment. Since the zigzag metal segment can be regarded as being composed of different strip metal units, gaps can be formed between different strip metal units. This allows the construction of the required equivalent inductance and equivalent capacitance to achieve the target band-stop resonant frequency without increasing the overall structural area of ​​the metal patch, which helps to achieve the miniaturization of the frequency selective surface 4.

[0032] Furthermore, since the frequency-selective surface 4 also captures electromagnetic waves in the target absorption frequency band and forms a surface current when the incident electromagnetic waves irradiate the central connecting metal patch 403, and different frequencies of incident electromagnetic waves have different electric field distributions on the central connecting metal patch 403, this embodiment determines the loading position of the resistor 10 on the central connecting metal patch 403 based on the electric field distribution of electromagnetic waves in the target absorption frequency band on the central connecting metal patch 403. The resistor 10 is loaded at a position where the surface current density formed by the electromagnetic waves in the target absorption frequency band is high, thereby effectively dissipating the surface current formed by the electromagnetic waves in the target absorption frequency band and ensuring the absorption effect. Simultaneously, the surface current density corresponding to the incident electromagnetic waves in the communication band is low at this loading position, so that the energy of this part of the incident electromagnetic waves is almost not consumed, thus ensuring low insertion loss for the transmission of incident electromagnetic wave signals in the communication band. For example, as... Figure 4 As shown, in one embodiment, the surface current formed by electromagnetic wave irradiation within the target absorption frequency band is mainly distributed at the end of the centrally connected metal patch 403, while the surface current corresponding to the incident electromagnetic wave in the communication band has a very small density at the end of the centrally connected metal patch 403. Therefore, two resistors 10 are loaded at the end of the centrally connected metal patch 403, which can further improve the absorption effect of incident electromagnetic waves within the target absorption frequency band.

[0033] Furthermore, in this embodiment, a first varactor diode 401 and a second varactor diode 402 are connected in parallel within the gap of the tortuous metal section, thereby forming a structure with adjustable protection characteristics. Utilizing the adjustable capacitance characteristic of the varactor diode, the active adjustment of the band-stop resonant frequency can be achieved. It can be understood that the junction capacitance of the varactor diode is inversely proportional to the reverse applied voltage. Therefore, its capacitance value can be adjusted by applying a bias voltage, thereby changing the overall impedance of the frequency selection surface 4 and thus changing the band-stop resonant frequency. This allows the electromagnetic protection device to have a variety of electromagnetic protection functions, including low insertion loss in the communication bandpass, frequency selection for incident electromagnetic waves, high-energy electromagnetic wave protection, wave absorption function, and adaptive adjustment of the band-stop resonant frequency. The functional integration is extremely high.

[0034] As a preferred embodiment, the energy selection surface 8 includes a plurality of periodically arranged metal patch units 801, each metal patch unit 801 having four arc-shaped defect openings 802 on its outer side and a circular defect region 803 inside its inner side; a diode 804 is disposed in the gap between two adjacent metal patch units 801 so that the diode 804 is connected in parallel with the equivalent capacitance corresponding to the gap in which it is located.

[0035] Please see Figure 5In this embodiment, the energy selection surface 8 is composed of multiple periodically arranged metal patch units 801. It can be understood that, compared with other conventional metal patch shapes, such as cross-shaped metal patches and rectangular metal patches, the metal patch units 801 in this embodiment are formed by circular cutting, that is, they have four arc-shaped defect openings 802 on the outside and circular defect areas 803 on the inside, forming a symmetrical metal structure shape. This shape makes it easier to control the equivalent capacitance value between adjacent metal patches. In addition, since the response speed of the diode 804 is affected by the electric field distribution on both sides, and the electric field distribution on both sides is controlled by the metal structure shape of the energy selection surface 8, the annular metal patch in this embodiment can guide the electric field to be more specifically distributed on both sides of the diode 804 compared with the rectangular metal patch, thereby ensuring timely shielding response to high-energy electromagnetic waves. Moreover, the metal patch units 801 in this embodiment can form a larger defect area in the energy selection surface 8, that is, the gap area between the metal patch units 801, thereby making it easier to reduce the interlayer coupling effect. In this embodiment, the energy selective surface 8, by setting the defect areas between the metal patch units 801 and the size of the circular defect areas 803 inside the metal patch units 801, can change the impedance characteristics of the overall structure, forming a specific communication band. This allows electromagnetic wave signals in this communication band to be transmitted through the defect areas (mainly achieving the transmission of 2.4GHz and 5.8GHz electromagnetic wave signals). When the diode 804 is turned on, it provides shielding and reflection of high-energy electromagnetic waves and forms a coupled resonance with the scattering-controlled metasurface structure, enhancing the absorption effect. The diode 804 can be selected according to the protection threshold requirements, i.e., determined by the minimum electromagnetic energy excitation threshold (determined by the carrying capacity of the internal components protected by the electromagnetic protection device) and the electromagnetic energy harvesting capacity of the energy selective surface 8 design structure. Optionally, the diode 804 is a MACOMMA4PBL027 (SOT-23 package) diode. By connecting diodes 804 between metal patch units 801, a current conduction path is formed between the metal patch units 801, and an equivalent parallel plate capacitor is formed between the metal patch units 801. When subjected to high-energy electromagnetic wave incident, since the arrangement position of diodes 804 is equivalent to being connected in parallel with the equivalent capacitance corresponding to the gap where they are located in the equivalent circuit diagram, it has a certain degree of forward bias voltage, so that diodes 804 are in a "subconducting state", realizing pre-conduction in advance, reducing the switching time from non-protected state to protected state, and achieving nanosecond-level dynamic response.

[0036] In this embodiment, the energy selective surface 8 is located at the bottom layer, so when subjected to high-energy electromagnetic wave attacks, the outer wave-absorbing layer 2 can still work stably while ensuring heat dissipation.

[0037] As a preferred embodiment, the device further includes a third dielectric substrate 7, and the scattering-modulated metasurface structure further includes a bias network layer 6; the third dielectric substrate 7 is disposed at the bottom of the second dielectric substrate 5, the energy selective surface 8 is disposed at the bottom of the third dielectric substrate 7, and the bias network layer 6 is disposed between the second dielectric substrate 5 and the third dielectric substrate 7. The bias network layer 6 is used to output a reverse regulation voltage to the first varactor diode 401 and the second varactor diode 402 to change the capacitance value of the first varactor diode 401 and the capacitance value of the second varactor diode 402, so that the communication bandpass changes with the change of the capacitance value of the first varactor diode 401 and the capacitance value of the second varactor diode 402.

[0038] Specifically, in this embodiment, the bias network layer 6 used to regulate the first varactor diode 401 and the second varactor diode 402 is disposed inside the electromagnetic protection device, instead of using an external bias network. This allows the bias network layer 6 to be shielded by both the upper metal patch structure and the energy selective surface 8. Compared to an external bias network, this greatly reduces the impact on the electromagnetic protection performance of the electromagnetic protection device. Simulation and experiments have shown that the absorption rate deviation before and after introducing the bias network layer 6 is less than 1%. Therefore, it can effectively eliminate the electromagnetic interference problem of external bias leads and make the structure of the electromagnetic protection device more compact.

[0039] It is worth noting that in this embodiment, the first varactor diode 401 and the second varactor diode 402 are equivalent to capacitors. C v The gap where the first varactor diode 401 and the second varactor diode 402 are located can be equivalent to a capacitor. C 0, Capacitance C v With capacitor C 0 represents a parallel relationship, and the center-connected metal patch 403 in the frequency selection surface 4 is equivalent to an inductor. L 1. Equivalent to an inductor in bias network layer 6. L 2. This forms an LC parallel resonant circuit, the equivalent impedance of which is... As shown below: ; Transmission pole frequency As shown below: ; When inductance L 1. Inductor L 2 and capacitor C When 0 is constant, the capacitance is changed by adjusting the reverse control voltage output by bias network layer 6. Cv The value of the capacitor, assuming capacitance C v The variable range is C v1 ≤ C v ≤ C v1 Then the adjustment boundary of the transmission pole frequency satisfies: ; ; The passband tuning factor α can be defined as the ratio of the maximum frequency of the transmission pole to the minimum frequency of the transmission pole, with the addition of a capacitor. C v Regulation factor β = C v2 / C v1 Then the passband tuning factor α can be expressed as: ; Therefore, for the first varactor diode 401 and the second varactor diode 402, a diode with both a wide capacitance adjustment range (i.e., a large β) and a low intrinsic capacitance (i.e., a large β) can be selected. C v1 A varactor diode with lower capacitance was developed, and its capacitance was minimized through structural optimization. C 0, to achieve a wide adjustment range of the band-stop resonant frequency, thereby ensuring a wide adjustment range of the communication bandwidth. In addition, the capacitor... C v The increase in frequency will lead to a gradual narrowing of the communication bandwidth, which needs to be addressed in practical designs by using capacitors. C The precise control of 0 ensures an acceptable communication bandwidth performance while maintaining a sufficient range for band-stop resonant frequency adjustment.

[0040] As a preferred embodiment, the bias network layer 6 includes a plurality of periodically arranged third metal units; the third metal unit includes a rectangular frame metal patch 601 corresponding to the second metal unit and a metal microstrip conductor 602 disposed within the rectangular frame metal patch 601; A through-hole penetrating the second dielectric substrate 5 is provided between the first varactor diode 401 and the second varactor diode 402. A metal connector 9 is provided in the through-hole. One end of the metal connector 9 is connected to the negative terminal of the first varactor diode 401 and the negative terminal of the second varactor diode 402, respectively. The other end of the metal connector 9 is connected to one end of the metal microstrip conductor 602. The other end of the metal microstrip conductor 602 is connected to the rectangular frame metal patch 601.

[0041] Please see Figure 6In this embodiment, the bias network layer 6 includes multiple periodically arranged third metal units to form a resonant structure. This allows the scattering-controlled metasurface structure to form a three-layer resonant structure, creating multiple transmission poles. This enables the acquisition of a specific frequency selection range, and within this range, the band-stop resonant frequency can be adjusted to achieve the desired communication bandwidth. Furthermore, the size of the rectangular metal patch 601 within the third metal unit is the same as that of the second metal unit, creating a one-to-one correspondence between the second and third metal units. The metal within the rectangular metal patch 601... The microstrip conductor 602 forms a radio frequency isolation structure. It is worth noting that the impedance of the metal microstrip conductor 602 is at least 128 ohms, and the higher the impedance, the better. A higher impedance necessitates a narrower width for the metal microstrip conductor 602. Optionally, due to manufacturing limitations, the width of the metal microstrip conductor 602 is chosen to be 0.2 mm. Since the metal microstrip conductor 602 is located inside the electromagnetic shielding device and is shielded by the upper metal patch structure and the energy selective surface 8, and because the metal microstrip conductor 602 has a high impedance, it can prevent electromagnetic waves during the electromagnetic shielding process from being converted into surface current on the metasurface and then discharged through the bias network layer 6. Preferably, the length of the metal microstrip conductor 602 is 1 / 4 of the wavelength of the dielectric medium corresponding to the center frequency of the communication band of the scattering-modulated metasurface structure.

[0042] This embodiment integrates the resonant structure of the frequency selection unit with the bias network layer 6 structure, and places the first varactor diode 401 and the second varactor diode 402 between the strip metal units of the tortuous metal segment to achieve an equivalent parallel connection effect with the planar structure, so that the resonant structure itself constitutes the bias current conduction path. For each third metal unit in this embodiment, the required reverse regulation voltage can be input through an external control system, and the voltage value can be adjusted from 0V to 20V.

[0043] As a preferred embodiment, the center-connected metal patch 403 is formed by bending at least one arm metal segment of the Jerusalem cross-shaped metal patch so that the frequency selection surface 4 has at least one band-stop resonant frequency.

[0044] Specifically, this embodiment forms the center-connected metal patch 403 in the frequency selection surface 4 by bending at least one arm metal segment of the Jerusalem cross-shaped metal patch. This effectively solves the frequency shift problem caused by changes in the incident angle of electromagnetic waves and achieves a complete electromagnetic response for the electromagnetic characteristics of TE and TM waves. Furthermore, the different lengths of the arm metal segments and the different gap widths between the strip metal units result in different impedance characteristics of the structure, thereby obtaining different band-stop resonant frequencies to achieve bandwidth adjustment of the communication bandpass.

[0045] Preferably, the center-connecting metal patch 403 in this embodiment is formed by making the same bending process on the four arm metal segments of the Jerusalem cross-shaped metal patch to ensure a small stopband range, thereby ensuring low insertion loss for communication signal transmission.

[0046] In a preferred embodiment, such as Figure 1 , Figure 5 and Figure 7 As shown in Table 1, the various dimensional parameters of the electromagnetic protection device are as follows: Table 1. Dimensional parameters of electromagnetic protection devices

[0047] in, p x and p y The dimensions (length and width) of the periodically arranged first metal unit, second metal unit, third metal unit and metal patch unit 801 are indicated. l 1 indicates the length of the strip metal unit at the center of the center-connected metal patch 403; l 2 represents the distance between the strip metal units on both sides of the first varactor diode 401 and the second varactor diode 402; l 3 represents the length of the strip metal units on both sides of the first varactor diode 401 and the second varactor diode 402; l 4 indicates the length of the strip metal unit connected to the end metal unit of the center-connected metal patch 403; l 5 represents the length of one of the rectangular metal patches in the metal patch structure 201; l 6 represents the length of another rectangular metal patch in the metal patch structure 201; l 7 indicates the length of the end metal unit of the center-connected metal patch 403; w 1 indicates the width of the tortuous metal segment; w 2 represents the width of the other rectangular metal patch described in metal patch structure 201; w 3 indicates the width of the end metal unit of the center-connected metal patch 403; w 4 indicates the line width of the rectangular metal patch 601; w 5 represents the width of one of the rectangular metal patches in the metal patch structure 201; w 6 indicates the width of the metal microstrip conductor 602; h 1 represents the thickness of the first dielectric substrate 1; h 2 represents the thickness of the second dielectric substrate 5; h 3 represents the thickness of the third dielectric substrate 7; hair This indicates the thickness of the air medium layer 3; L 1 represents the width of the metal patch unit 801 in the energy selection surface 8; L 2 indicates the spacing between the metal patch units 801 in the energy selection surface 8; R 1 represents the radius of the circular defect region 803 within the metal patch unit 801; R 2 represents the radius of the defect area surrounded by the four metal patch units 801.

[0048] Based on the above structural dimensions design, a frequency-selective region of 2.4GHz to 7.0GHz and an absorbing band of 7.5GHz to 15GHz can be formed. Within the 2.4GHz to 7.0GHz frequency-selective region, the equivalent capacitance values ​​of the first varactor diode 401 and the second varactor diode 402 are adjusted within the range of 0.1pF to 1pF through the bias network layer 6, thereby achieving adjustment of the communication bandpass. The specific communication bandpass changes, absorbing band, and shielding effectiveness are as follows: Figure 8 As shown, in Figure 8 It includes shielding effectiveness curves and amplitude-frequency response curves of the electromagnetic protection device under different equivalent capacitance values ​​of the first varactor diode 401 and the second varactor diode 402. Different colored curves represent the amplitude-frequency response under different equivalent capacitance values. Figure 8 The communication bandwidth in the diagram can be understood as follows: when the equivalent capacitance values ​​of the first varactor diode 401 and the second varactor diode 402 are small, the band-stop resonant frequency of the scattering-modulated metasurface structure is high. Therefore, from the amplitude-frequency response curve, there is a relatively wide communication bandwidth located to the left of the band-stop resonant frequency within the frequency-selective region. When the equivalent capacitance value of the first varactor diode 401 and the second varactor diode 402 is 0.1 pF, the communication bandwidth is 3.86 GHz to 6.17 GHz; when the equivalent capacitance value of the first varactor diode 401 and the second varactor diode 402 is 0.2 pF, the communication bandwidth is 3.62 GHz to 5.33 GHz. GHz; when the equivalent capacitance of the first varactor diode 401 and the second varactor diode 402 is 0.3pF, the communication bandwidth is 3.35GHz~4.60GHz; when the equivalent capacitance of the first varactor diode 401 and the second varactor diode 402 exceeds 0.4pF, due to the increase in equivalent capacitance, the band-stop resonant frequency of the scattering-controlled metasurface structure decreases accordingly, manifested as Figure 8 The minimum point of the mid-amplitude frequency response curve shifts continuously to the left within the frequency-selective region, and the quality factor also changes, causing a change in its stopband bandwidth. This directly affects the relative position and bandwidth of the communication bands located on either side, such as... Figure 8The diagram shows dual-passband frequencies of 3.13 GHz to 4.15 GHz and 6.28 GHz to 7.05 GHz, respectively. When the equivalent capacitance of the first varactor diode 401 and the second varactor diode 402 is 0.6 pF, the dual-passband frequencies are 2.84 GHz to 3.58 GHz and 5.95 GHz to 7.00 GHz, respectively. When the equivalent capacitance of the first varactor diode 401 and the second varactor diode 402 is 0.8 pF, the dual-passband frequencies are 2.66 GHz to 3.27 GHz and 5.82 GHz to 6.95 GHz, respectively. When the equivalent capacitance of the first varactor diode 401 and the second varactor diode 402 is 1 pF, the dual-passband frequencies are 2.39 GHz to 2.87 GHz and 5.64 GHz to 6.93 GHz, respectively. Therefore, during the regulation of the first varactor diode 401 and the second varactor diode 402 by the bias network layer 6, as the equivalent capacitance value increases, the band-stop resonant frequency of the scattering-regulated metasurface structure gradually decreases, thus gradually presenting a dual-passband situation in the frequency-selective region. Among them, the communication passband of the lower frequency continuously narrows, while the communication passband of the higher frequency continuously expands. In this regulation process, the electromagnetic protection capability can always be maintained, and the absorbing band will not be affected, that is, the absorbing performance does not change.

[0049] Depend on Figure 8 As can be seen from the shielding effectiveness curve, this embodiment has a good shielding effect on electromagnetic waves in the non-communication band passband and the absorbing band within the frequency-selective area, thus indicating that the electromagnetic protection device of this embodiment can have a good electromagnetic protection effect while having multiple electromagnetic protection functions.

[0050] A second aspect of the present invention provides an antenna, the antenna comprising an electromagnetic protection device based on a metasurface as described in any embodiment of the first aspect.

[0051] A third aspect of the present invention provides an electronic device, the electronic device including the antenna as described in the second aspect.

[0052] The electromagnetic protection device, antenna, and electronic equipment based on metasurfaces provided in this invention integrate a scattering-modulated metasurface structure and an energy-selective surface. The energy-selective surface provides adaptive protection against high-power electromagnetic waves. The scattering-modulated metasurface located above the energy-selective surface allows transmission of incident electromagnetic waves in the communication band while absorbing incident electromagnetic waves in the target absorption band and reflected electromagnetic waves from the energy-selective surface. This ensures stable communication links for UAVs in complex electromagnetic environments and low insertion loss transmission in the communication band. It also provides high-energy electromagnetic wave protection and improves the stealth performance of UAVs, thus meeting the electromagnetic protection requirements of UAVs in complex electromagnetic environments.

[0053] Furthermore, the electromagnetic protection device in this embodiment of the invention can be prepared based on standard multilayer printed circuit board technology and surface mount technology. The process is mature, the cost is low, and it is easy to mass-produce.

[0054] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. An electromagnetic protection device based on metasurfaces, characterized in that, It includes a scattering-controlled metasurface structure and an energy-selective surface; the scattering-controlled metasurface structure is disposed above the energy-selective surface; the scattering-controlled metasurface structure is used to transmit incident electromagnetic waves in the communication band and absorb incident electromagnetic waves in the target absorption band and reflected electromagnetic waves from the energy-selective surface.

2. The electromagnetic protection device based on metasurface as described in claim 1, characterized in that, The scattering-controlled metasurface structure includes a first dielectric substrate, an absorbing layer, an air dielectric layer, a frequency selective surface, and a second dielectric substrate; the absorbing layer is disposed at the bottom of the first dielectric substrate, the frequency selective surface is disposed at the top of the second dielectric substrate, and the air dielectric layer is disposed between the absorbing layer and the frequency selective surface.

3. The electromagnetic protection device based on metasurface as described in claim 2, characterized in that, The absorbing layer includes a plurality of periodically arranged and rotationally symmetrical first metal units; each first metal unit includes a plurality of metal patch structures, each metal patch structure being formed by connecting a plurality of rectangular metal patches, two of the rectangular metal patches being perpendicular to each other, and at least one resistor being loaded on the rectangular metal patch; wherein, the loading position of the resistor is determined based on the electric field distribution of the electromagnetic wave in the target absorbing frequency band on the rectangular metal patch.

4. The electromagnetic protection device based on metasurface as described in claim 2, characterized in that, The frequency selective surface includes a plurality of periodically arranged second metal units; the second metal unit includes a center-connected metal patch with a tortuous metal segment; at least one resistor is loaded on the center-connected metal patch, and a first varactor diode and a second varactor diode are connected within the gap of the tortuous metal segment; wherein, the loading position of the resistor is determined based on the electric field distribution of the electromagnetic wave in the target absorbing frequency band on the center-connected metal patch.

5. The electromagnetic protection device based on metasurface as described in claim 1, characterized in that, The energy selective surface includes multiple periodically arranged metal patch units. Each metal patch unit has four arc-shaped defect openings on its outer side and a circular defect area inside. A diode is disposed in the gap between two adjacent metal patch units so that the diode is connected in parallel with the equivalent capacitance corresponding to the gap it is located in.

6. The electromagnetic protection device based on metasurface as described in claim 4, characterized in that, The device further includes a third dielectric substrate, and the scattering-modulated metasurface structure further includes a bias network layer; the third dielectric substrate is disposed at the bottom of the second dielectric substrate, the energy selective surface is disposed at the bottom of the third dielectric substrate, and the bias network layer is disposed between the second dielectric substrate and the third dielectric substrate. The bias network layer is used to output a reverse regulation voltage to the first varactor diode and the second varactor diode to change the capacitance value of the first varactor diode and the second varactor diode, so that the communication bandpass changes with the change of the capacitance value of the first varactor diode and the second varactor diode.

7. The electromagnetic protection device based on metasurface as described in claim 6, characterized in that, The bias network layer includes a plurality of periodically arranged third metal units; each third metal unit includes a rectangular metal patch corresponding to the second metal unit and a metal microstrip conductor disposed within the rectangular metal patch; A through-hole penetrating the second dielectric substrate is provided between the first varactor diode and the second varactor diode. A metal connector is provided in the through-hole. One end of the metal connector is connected to the negative terminal of the first varactor diode and the negative terminal of the second varactor diode, respectively. The other end of the metal connector is connected to one end of the metal microstrip wire. The other end of the metal microstrip wire is connected to the rectangular frame metal patch.

8. The electromagnetic protection device based on metasurface as described in claim 4, characterized in that, The center-connected metal patch is formed by bending at least one arm of the Jerusalem cross-shaped metal patch so that the frequency selection surface has at least one band-stop resonant frequency.

9. An antenna, characterized in that, The antenna includes the metasurface-based electromagnetic protection device as described in any one of claims 1 to 8.

10. An electronic device, characterized in that, The electronic device includes the antenna as described in claim 9.

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