A method for protecting a drone body from high power microwaves

Abstract

The present application belongs to the field of unmanned aerial vehicle electromagnetic countermeasures, high-power microwave protection and electromagnetic compatibility reinforcement, and particularly relates to a high-power microwave protection method for unmanned aerial vehicle body, which realizes lightweight global shielding by arranging three layers of gradient frequency selective composite skin on the unmanned aerial vehicle body; micro plasma units are arranged on the body gap, and the whole machine cable is replaced by optical fiber to double block the back door microwave coupling; a reconfigurable antenna, two-stage series limiting and a neural network adaptive filtering three-level radio frequency decoupling link are built on the nose; four groups of broadband sensors are arranged on the body to realize microsecond-level electromagnetic threat perception grading; a flight control closed-loop self-healing regulation system containing a bionic optimization algorithm is constructed, which can dynamically adjust the protection power consumption and automatically redundantly reconstruct the fault. The present application can realize a shielding efficiency of the whole machine of greater than or equal to 40 dB under a 1~18GHz, 20kV / m high field intensity environment, and can balance lightweight, communication signal fidelity and long endurance, effectively avoiding problems such as gap resonance, device breakdown and communication interruption, and is suitable for fixed-wing, vertical take-off and landing low-altitude unmanned aerial vehicles.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic countermeasures, high-power microwave protection and electromagnetic compatibility hardening technology for unmanned aerial vehicles (UAVs), and specifically relates to a method for high-power microwave protection of UAV airframes. Background Technology

[0002] High-power microwave anti-drone attack sources, with their characteristics of wide bandwidth coverage, high field strength penetration, non-contact damage, and wide-area suppression, have become the mainstream hard / soft damage attack sources in low-altitude countermeasures. High-power microwaves mainly penetrate the drone body through two paths: front-door radio frequency coupling and rear-door structural gap coupling, causing damage effects such as radio frequency front-end blockage, chip breakdown, power surge, flight control failure, and attitude loss and crash.

[0003] Existing high-power microwave protection technologies for drones have inherent structural defects, which are also technical bottlenecks that the industry cannot overcome at present. These defects can be divided into three categories: Category 1: Traditional single-layer metal shielding / wave-absorbing passive protection This type of solution relies solely on metal coatings, metal skins, and conventional ferrite absorbing materials for shielding, which has three major fatal flaws: 1) It lacks frequency selectivity, exhibits uniform attenuation across the entire frequency band, and cannot distinguish between useful signals and interference signals; 2) The coupling between the gaps and openings is severe, the structure lacks the ability to block back doors, and the shielding effectiveness deteriorates sharply under high field strength; 3) Excessive weight gain and poor adaptability make it impossible to meet the requirements of lightweight, long-endurance, and high maneuverability for drones; 4) It lacks self-adaptive capability, and fixed protection parameters cannot adapt to dynamic electromagnetic threats.

[0004] Category 2: Single-limiting and fixed-filter protection for RF front-end Traditional solutions only use PIN limiters, Zener diodes, and fixed filters for front-end protection, which have the following drawbacks: 1) High field strength makes it prone to breakdown and severe peak leakage; it is basically ineffective in environments above 20kV / m. 2) It lacks frequency and polarization identification capabilities, making it unable to suppress coupling energy at the source; 3) Fixed parameters lack intelligent adjustment capabilities, making it impossible to balance anti-interference and signal fidelity.

[0005] Category 3: Purely passive structural protection, with no alarms, no closed-loop system, and no self-healing. All currently available publicly available drone microwave protection technologies are static, passive protection systems and do not possess the following characteristics: 1) The ability to proactively perceive and predict threats; 2) Dynamic adjustment mechanism for protection parameters; 3) Fault redundancy reconstruction and system self-healing capability.

[0006] In summary, existing technologies are all simple superpositions of conventional electromagnetic shielding, conventional amplitude limiting, and conventional wave absorption. They do not have an integrated system of "layered frequency-selective shielding + plasma backdoor adaptive blocking + antenna source suppression and microsecond-level alarm closed-loop self-healing", which is also a blank technology direction in this field. Summary of the Invention

[0007] To address the technical problems existing in the current high-power microwave protection technology for UAVs, this invention provides a method for high-power microwave protection of UAV airframes.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for protecting the airframe from high-power microwaves of unmanned aerial vehicles (UAVs) includes the following steps: S1. Three layers of gradient frequency-selective composite skin are deployed to cover the entire outer surface of the UAV to construct a global gradient passive shielding base layer, thereby achieving band-stop attenuation of interference signals, lossless transmission of communication passband signals, and absorption of residual microwave energy inside the cabin. S2. Install miniature array plasma protection units in all rear door coupling channels, such as gaps in the UAV cabin door, cable penetration holes, sensor mounting holes, and heat dissipation holes, and replace all signal cables and power cables with optical fibers to block microwave coupling from the rear door through structural gaps and electrical conduction dual channels. S3. A three-level intelligent protection link for radio frequency front-end is built at the radio frequency antenna end of the drone nose. The interference source is decoupled through a reconfigurable antenna. A two-level series limiting structure is used to intercept high field strength peak microwaves. An embedded neural network adaptive filter is then used to distinguish between effective communication signals and microwave interference. S4. Deploy multiple broadband electromagnetic monitoring sensors around the drone fuselage to establish a 1~18GHz full-domain electromagnetic threat real-time alarm mechanism, and complete the collection and analysis of microwave field strength, frequency band, and incident direction in microseconds to classify electromagnetic threat levels. S5. Construct a flight control closed-loop self-healing control logic that includes threat perception, graded protection execution, avionics status monitoring, protection effect evaluation, parameter adaptive optimization, and fault redundancy reconstruction. It adopts a biomimetic mapping algorithm to dynamically balance protection effectiveness and airborne power consumption. When a protection unit fails, it automatically switches to a backup path to achieve uninterrupted self-healing protection during flight.

[0009] The total thickness of the three-layer gradient frequency selective composite skin is controlled at 0.8~1.2mm, and the weight per square meter is ≤180g. From the outside to the inside, it consists of a three-layer gradient synergistic structure: an FSS frequency selective surface layer, a graphene-carbon fiber composite shielding layer, and a flexible carbonyl iron powder absorbing buffer layer. The outer FSS frequency selective surface layer achieves band-stop attenuation of high-power microwave interference from 1 to 18 GHz, with no significant attenuation of the communication passband signal; the middle graphene-carbon fiber composite shielding layer provides secondary shielding against residual microwave energy penetrating the outer layer; the inner flexible carbonyl iron powder absorbing layer absorbs residual electromagnetic energy reflected multiple times from the interior of the aircraft, eliminating electromagnetic resonance coupling within the cabin.

[0010] The FSS frequency selective surface layer uses a flexible polyimide substrate and is fabricated by photolithography etching to form a periodic square metal patch array with a unit period size of 8.5 mm, a metal patch width of 6.2 mm, and a band-stop shielding effectiveness of ≥35 dB.

[0011] The graphene-carbon fiber composite shielding layer is formed by spraying, with a raw material ratio of 70% chopped carbon fiber and 30% graphene. After curing, it forms a high-strength conductive shielding layer, which makes up for the high-frequency shielding shortcomings of the FSS layer and is suitable for the aerodynamic loads of UAVs during high-speed flight.

[0012] The flexible carbonyl iron powder microwave absorbing buffer layer has a thickness of 0.3 mm and is used to suppress the superposition of microwave energy inside the cabin, avoiding electromagnetic damage to avionics and flight control chips.

[0013] The individual volume of the miniature array plasma protection unit is ≤2cm². 3 It has a built-in miniature inert gas ionization cavity and a high-frequency microvolt excitation power supply. Under normal conditions, it is in hibernation with no additional power consumption. When the external microwave field strength is >5kV / m, the excitation power supply automatically starts to ionize the inert gas to generate plasma. The plasma ionization concentration increases nonlinearly with the increase of the external microwave field strength. Under the extreme condition of 20kV / m, the plasma shielding effectiveness is ≥40dB, which suppresses microwave resonance penetration through gaps.

[0014] The radio frequency front-end three-level intelligent protection link specifically includes a front-end reconfigurable antenna, a mid-end PIN limiter and a micro plasma limiter two-stage series limiting component, and a back-end lightweight embedded neural network filtering module. The reconfigurable antenna integrates a polarization identification and frequency sensing chip, dynamically adjusting the antenna radiating element arrangement within 1μs to achieve 15~20dB source coupling energy attenuation for interference signals; the two-stage series limiting component uses a PIN limiter to suppress low-to-medium field strength spike signals and a micro plasma limiter to intercept high-field strength breakdown spike leakage, and can withstand 20kV / m microwave irradiation without breakdown failure; the neural network filtering module, after sample training, distinguishes between effective communication signals and microwave interference, improving the interference filtering accuracy by more than 95% compared to traditional fixed filtering.

[0015] The wideband electromagnetic monitoring sensors are deployed in four groups, covering a monitoring frequency range of 1~18GHz, and the sensor response speed is ≤0.5μs. The airborne main control chip classifies electromagnetic threats into four levels: slight, moderate, severe, and extremely severe, based on the collected field strength data, and activates differentiated protection strategies for different levels.

[0016] The biomimetic mapping algorithm operates as follows: in low electromagnetic threat scenarios, the power consumption of the plasma protection unit and the radio frequency protection link is reduced; in high electromagnetic threat scenarios, all protection units operate at full load, balancing the overall protection performance and the drone's endurance.

[0017] The protection method is compatible with fixed-wing and vertical take-off and landing UAVs. The protective structure is lightweight and integrated, without requiring any changes to the original aerodynamic layout, flight control system, and payload installation structure of the UAV. After continuous irradiation test with 20kV / m high field strength microwaves across the 1~18GHz full frequency band, the shielding effectiveness of the UAV as a whole is stable at ≥40dB, and there are no crashes, signal interruptions, or device breakdowns in the flight control, navigation, and data transmission systems.

[0018] Compared with the prior art, the beneficial effects of this invention are: 1. This invention employs a three-layer gradient frequency-selective composite skin paired with a micro-plasma backdoor blocking unit. The total thickness of the composite skin is only 0.8~1.2mm, and the areal density does not exceed 180g / m³. 2 Its lightweight characteristics are suitable for the long endurance and high maneuverability requirements of UAVs; the outer FSS structure can achieve 1~18GHz interference band-stop and lossless transmission of communication signals, avoiding the navigation and data transmission interruption problem caused by traditional full-frequency shielding; the plasma unit has field strength adaptive shielding characteristics, and the gap shielding efficiency can reach more than 40dB under a high field strength of 20kV / m, completely suppressing gap resonance penetration. At the same time, the fiber optic cable replaces the cable to eliminate conducted coupling. Compared with the traditional single-layer metal shielding and fixed sealing solution, it solves the three major pain points of serious weight increase, lack of frequency selectivity and high field strength shielding failure.

[0019] 2. This invention reduces microwave coupling energy at the source through a reconfigurable antenna, and uses a two-stage series limiting method of PIN and plasma to resist breakdown from ultra-high field strength spikes. It also relies on neural network adaptive filtering to accurately distinguish between interference and valid signals. It can achieve 15~20dB of interference source attenuation, and the RF link can be maintained without breakdown failure under continuous microwave irradiation of 20kV / m. The interference filtering accuracy is more than 95% higher than that of traditional fixed filtering. It perfectly balances the high-power microwave damage resistance requirements with the normal communication and navigation signal transmission requirements of UAVs, and solves the industry problem of high field strength failure of single limiters and the inability of fixed filtering to simultaneously achieve anti-interference and signal fidelity.

[0020] 3. This invention is equipped with a wideband electromagnetic monitoring sensor with a response speed of ≤0.5μs, which can identify and classify electromagnetic threats in advance and trigger differentiated protection strategies, thus breaking away from the traditional purely static passive protection mode. It dynamically adjusts the operating power consumption of each protection unit based on a biomimetic mapping algorithm. In low-threat conditions, it reduces power consumption to ensure the drone's endurance, while in high-threat conditions, it operates at full load to improve protection performance. At the same time, it has the ability to reconstruct fault redundancy. When any protection unit fails, it automatically switches to the backup path, ensuring uninterrupted protection throughout the flight. This forms a complete intelligent protection closed loop of "perception-control-evaluation-self-healing", which greatly improves the survivability and reliability of drones in complex electromagnetic confrontation environments. Attached Figure Description

[0021] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0022] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0023] Figure 1 A schematic diagram of the cross-sectional structure of the three-layer composite shielding skin of a drone; Figure 2 Here is the overall closed-loop control flowchart for a high-power microwave protection system; Figure 3 A schematic diagram of the installation of the coupling blocking structure at the rear door of the aircraft. Figure 4 This is an architecture diagram of a multi-level protection module for the radio frequency front end. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. These descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the claims of the present invention. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0026] 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 a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0027] The protection system in this embodiment is adapted to vertical take-off and landing fixed-wing UAVs. The overall protection structure is lightweight and integrated, without requiring any changes to the original aerodynamic layout, flight control hardware, or payload installation structure of the UAV. The protection system is composed of five core units working together: a three-layer gradient frequency-selective composite skin, a micro-array plasma backdoor protection unit, a three-level intelligent protection link for the radio frequency front end, a microsecond-level broadband electromagnetic threat monitoring module, and a flight control closed-loop self-healing control module.

[0028] Example 1: Implementation of a Three-Layer Gradient Frequency-Selective Composite Skin The entire outer surface of the machine is covered with a three-layer gradient frequency-selective composite skin, with the total skin thickness controlled between 0.8 and 1.2 mm, and the weight per square meter ≤ 180 g. Figure 1 As shown, from the outside to the inside, there are three gradient synergistic structures: the FSS frequency selective surface layer, the graphene-carbon fiber composite shielding layer, and the flexible carbonyl iron powder absorbing buffer layer.

[0029] The outer FSS frequency selective surface layer uses flexible polyimide as the substrate and a periodic square metal patch array is fabricated using photolithography etching process. The array unit period size is 8.5mm and the metal patch width is 6.2mm. This layer provides band-stop attenuation for high-power microwave interference signals from 1 to 18GHz, with a band-stop shielding effectiveness of ≥35dB. At the same time, it ensures that there is no significant attenuation of the passband signals of Beidou, GPS, and data transmission, avoiding the communication loss defects caused by traditional full-frequency metal shielding.

[0030] The middle layer of graphene-carbon fiber composite shielding is formed by spraying. The spraying raw material ratio is 70% short-cut carbon fiber and 30% graphene. After curing, it forms a high-strength conductive shielding layer, which provides secondary shielding for residual microwave energy that penetrates the outer FSS layer, making up for the shortcomings of FSS high-frequency shielding. It also has high tensile strength and deformation resistance, and can be adapted to the aerodynamic load of UAVs during high-speed flight.

[0031] The inner flexible carbonyl iron powder microwave absorbing buffer layer has a fixed thickness of 0.3mm, which fits tightly against the UAV fuselage. It absorbs the residual electromagnetic energy reflected multiple times inside the fuselage, eliminates the superposition effect of electromagnetic resonance inside the cabin, and avoids the accumulation of microwave energy inside the fuselage, which could cause burn-out damage to the flight control chip and avionics components.

[0032] Example 2: Implementation of a Miniature Array Plasma Back-Gate Coupling Blocking Unit For all rear door coupling channels, such as gaps in the drone's cabin door, cable penetration holes, sensor mounting holes, and heat dissipation holes, such as... Figure 3 As shown, a miniature array of plasma protection units is deployed, with each unit having a volume ≤2cm². 3 The unit integrates a miniature inert gas ionization chamber and a high-frequency microvolt excitation power supply.

[0033] Under normal conditions without strong microwave threats, the excitation power supply is in sleep mode, and the unit consumes no additional power, relying solely on the conductive sealing rubber of the fuselage for basic shielding. When the airborne monitoring sensor detects an external microwave field strength > 5kV / m, the excitation power supply automatically starts, and the inert gas in the ionization cavity generates plasma. The plasma ionization concentration increases nonlinearly with the increase of the external microwave field strength. When the external field strength reaches the extreme condition of 20kV / m, the plasma shielding effectiveness can reach more than 40dB, suppressing the gap resonance penetration effect.

[0034] Simultaneously, fiber optic replacement was carried out on all signal cables and power cables of the UAV to completely cut off the conductive microwave coupling channel of the cables; relying on plasma unit to block structural gap coupling and fiber optic replacement to block electrical conductive coupling, the dual back door coupling path was completely blocked.

[0035] Example 3: Implementation of a Three-Level Intelligent Protection Link for the RF Front-End Integrating a three-level linkage intelligent protection link at the drone's nose communication and navigation radio frequency antenna end, such as Figure 4 As shown, the link hierarchy consists of a front-end reconfigurable antenna, a mid-end PIN limiter + micro plasma limiter two-stage series limiting component, and a back-end lightweight embedded neural network filtering module.

[0036] The front-end reconfigurable antenna integrates polarization identification and frequency sensing chips, which can identify the incident microwave interference frequency band and polarization mode in real time, dynamically adjust the antenna radiating element arrangement within 1μs, change the antenna impedance and receiving gain, and achieve 15~20dB source coupling energy attenuation for incident interference, thereby reducing microwave energy entering the radio frequency system from the source.

[0037] The two-stage series limiting components in the middle stage work together: the PIN limiter is responsible for suppressing the peak signals of conventional low and medium field strength, while the miniature plasma limiter is specifically designed to intercept high field strength breakdown peaks and leakage energy. The entire link can withstand continuous irradiation of 20kV / m high field strength microwaves without breakdown failure, solving the problem of rapid failure of a single PIN limiter under high field strength and serious peak leakage.

[0038] The backend is equipped with a lightweight embedded neural network filtering module, which is pre-trained using a large number of communication signals and microwave interference samples. It can distinguish between effective navigation / data transmission signals and random microwave interference in real time, and dynamically and adaptively adjust the filtering parameters. Compared with traditional fixed parameter filtering, the interference filtering accuracy is improved by more than 95%, while taking into account both damage protection and communication signal fidelity.

[0039] Example 4: Implementation of a Microsecond-Level Global Electromagnetic Threat Alarm Module Four sets of broadband electromagnetic monitoring sensors are evenly deployed around the fuselage of the UAV. The sensors monitor a full range of frequencies from 1 to 18 GHz, and the signal response speed of a single sensor is ≤0.5 μs. They can collect three-dimensional electromagnetic parameters such as external microwave field strength, interference frequency band, and incident direction in real time, and transmit the collected data to the onboard main control chip in real time.

[0040] The airborne main control chip classifies electromagnetic threats into four levels based on real-time field strength values: slight, moderate, severe, and extremely severe. Different threat levels trigger differentiated graded protection strategies. For slight threats, only basic shielding is maintained; for moderate threats, the plasma unit is activated to operate at low power; for severe threats, the radio frequency protection link is fully activated; and for extremely severe threats, all protection units are activated and maneuver evasion commands are simultaneously pushed to the flight control system, achieving early warning and graded protection, thus changing the traditional passive protection mode.

[0041] Example 5: Implementation of the Flight Control Closed-Loop Self-Healing Regulation System The airborne main control chip is equipped with complete closed-loop control logic, such as... Figure 2 As shown, the process is as follows: electromagnetic threat perception and acquisition → activation of hierarchical protection units → real-time monitoring of avionics and protection hardware status → online evaluation of protection effectiveness → adaptive optimization of biomimetic mapping algorithm parameters → fault redundancy reconstruction.

[0042] The system incorporates a biomimetic mapping algorithm to dynamically balance the overall protection performance and airborne power consumption: in low electromagnetic threat scenarios, the operating power of the plasma unit and radio frequency filter module is reduced to decrease the overall power consumption and extend the drone's endurance; in high electromagnetic threat scenarios, all protection units are controlled to operate at full load to maximize shielding and anti-damage performance.

[0043] The system has multiple built-in backup protection paths and monitors the working status of the three-layer composite skin's supporting monitoring nodes, plasma unit, and radio frequency link hardware in real time. When any protection unit fails, the system immediately and automatically switches to the redundant backup path, ensuring uninterrupted protection during flight and achieving self-healing and reconfiguration.

[0044] Example 6: Implementation of Overall Machine Integration Assembly and Performance Verification The above five-layer protection unit is lightweight and integrated into a conventional vertical take-off and landing UAV. The assembly process does not require modification of the original aerodynamic shape, flight control motherboard, or optoelectronic payload installation structure of the UAV. All protection modules adopt a lightweight solution of external mounting, attachment, and internal integration.

[0045] Through joint verification using CST electromagnetic simulation platform simulation and external radiation irradiation test: Under continuous microwave irradiation conditions with a high field strength of 20kV / m across the entire 1~18GHz frequency band, the shielding effectiveness of the UAV is stable at ≥40dB; throughout the flight, the flight control, navigation, and data transmission systems are unblocked, without crashes, signal interruptions, or component breakdowns and burnouts; there is no microwave resonance penetration phenomenon in the fuselage gaps, and no peak energy leakage in the RF link; the increase in overall weight is controlled within the allowable range, without changing the original flight maneuverability and endurance of the UAV, and it can be mass-produced and adapted to various fixed-wing and vertical take-off and landing UAVs to complete the engineering implementation.

[0046] The above description only illustrates the preferred embodiments of the present invention. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention, and all such changes should be included within the protection scope of the present invention.

Claims

1. A method for protecting the airframe of a drone from high-power microwaves, characterized in that, Includes the following steps: S1. Three layers of gradient frequency-selective composite skin are deployed to cover the entire outer surface of the UAV to construct a global gradient passive shielding base layer, thereby achieving band-stop attenuation of interference signals, lossless transmission of communication passband signals, and absorption of residual microwave energy inside the cabin. S2. Install miniature array plasma protection units in all rear door coupling channels, such as gaps in the UAV cabin door, cable penetration holes, sensor mounting holes, and heat dissipation holes, and replace all signal cables and power cables with optical fibers to block microwave coupling from the rear door through structural gaps and electrical conduction dual channels. S3. A three-level intelligent protection link for radio frequency front-end is built at the radio frequency antenna end of the drone nose. The interference source is decoupled through a reconfigurable antenna. A two-level series limiting structure is used to intercept high field strength peak microwaves. An embedded neural network adaptive filter is then used to distinguish between effective communication signals and microwave interference. S4. Deploy multiple broadband electromagnetic monitoring sensors around the drone fuselage to establish a 1~18GHz full-domain electromagnetic threat real-time alarm mechanism, and complete the collection and analysis of microwave field strength, frequency band, and incident direction in microseconds to classify electromagnetic threat levels. S5. Construct a flight control closed-loop self-healing control logic that includes threat perception, graded protection execution, avionics status monitoring, protection effect evaluation, parameter adaptive optimization, and fault redundancy reconstruction. It adopts a biomimetic mapping algorithm to dynamically balance protection effectiveness and airborne power consumption. When a protection unit fails, it automatically switches to a backup path to achieve uninterrupted self-healing protection during flight.

2. The method for high-power microwave protection of a UAV body according to claim 1, characterized in that: The total thickness of the three-layer gradient frequency selective composite skin is controlled at 0.8~1.2mm, and the weight per square meter is ≤180g. From the outside to the inside, it consists of a three-layer gradient synergistic structure: an FSS frequency selective surface layer, a graphene-carbon fiber composite shielding layer, and a flexible carbonyl iron powder absorbing buffer layer. The outer FSS frequency selective surface layer achieves band-stop attenuation of high-power microwave interference from 1 to 18 GHz, while the communication passband signal shows no significant attenuation. The middle layer of graphene-carbon fiber composite shielding provides secondary shielding against residual microwave energy penetrating the outer layer; the inner layer of flexible carbonyl iron powder absorbing layer absorbs residual electromagnetic energy reflected multiple times from the interior of the aircraft, eliminating electromagnetic resonance coupling within the cabin.

3. The method for high-power microwave protection of a UAV body according to claim 2, characterized in that: The FSS frequency selective surface layer uses a flexible polyimide substrate and is fabricated by photolithography etching to form a periodic square metal patch array with a unit period size of 8.5 mm, a metal patch width of 6.2 mm, and a band-stop shielding effectiveness of ≥35 dB.

4. A method for high-power microwave protection of a UAV fuselage according to claim 2, characterized in that: The graphene-carbon fiber composite shielding layer is formed by spraying, with a raw material ratio of 70% chopped carbon fiber and 30% graphene. After curing, it forms a high-strength conductive shielding layer, which makes up for the high-frequency shielding shortcomings of the FSS layer and is suitable for the aerodynamic loads of UAVs during high-speed flight.

5. A method for high-power microwave protection of a UAV airframe according to claim 2, characterized in that: The flexible carbonyl iron powder microwave absorbing buffer layer has a thickness of 0.3 mm and is used to suppress the superposition of microwave energy inside the cabin, avoiding electromagnetic damage to avionics and flight control chips.

6. The method for high-power microwave protection of a UAV fuselage according to claim 1, characterized in that: The individual volume of the miniature array plasma protection unit is ≤2cm². 3 It has a built-in miniature inert gas ionization cavity and a high-frequency microvolt excitation power supply. Under normal conditions, it is in hibernation with no additional power consumption. When the external microwave field strength is >5kV / m, the excitation power supply automatically starts to ionize the inert gas to generate plasma. The plasma ionization concentration increases nonlinearly with the increase of the external microwave field strength. Under the extreme condition of 20kV / m, the plasma shielding effectiveness is ≥40dB, which suppresses microwave resonance penetration through gaps.

7. A method for high-power microwave protection of a UAV fuselage according to claim 1, characterized in that: The radio frequency front-end three-level intelligent protection link specifically includes a front-end reconfigurable antenna, a mid-end PIN limiter and a micro plasma limiter two-stage series limiting component, and a back-end lightweight embedded neural network filtering module. The reconfigurable antenna integrates a polarization identification and frequency sensing chip, dynamically adjusting the antenna radiating element arrangement within 1μs to achieve 15~20dB source coupling energy attenuation for interference signals; the two-stage series limiting component uses a PIN limiter to suppress low-to-medium field strength spike signals and a micro plasma limiter to intercept high-field strength breakdown spike leakage, and can withstand 20kV / m microwave irradiation without breakdown failure; the neural network filtering module, after sample training, distinguishes between effective communication signals and microwave interference, improving the interference filtering accuracy by more than 95% compared to traditional fixed filtering.

8. A method for protecting a UAV fuselage from high-power microwaves according to claim 1, characterized in that: The wideband electromagnetic monitoring sensors are deployed in four groups, covering a monitoring frequency range of 1~18GHz, and the sensor response speed is ≤0.5μs. The airborne main control chip classifies electromagnetic threats into four levels: slight, moderate, severe, and extremely severe, based on the collected field strength data, and activates differentiated protection strategies for different levels.

9. A method for high-power microwave protection of a UAV fuselage according to claim 1, characterized in that, The biomimetic mapping algorithm operates as follows: in low electromagnetic threat scenarios, the power consumption of the plasma protection unit and the radio frequency protection link is reduced; in high electromagnetic threat scenarios, all protection units operate at full load, balancing the overall protection performance and the drone's endurance.

10. A method for high-power microwave protection of a UAV fuselage according to claim 1, characterized in that: The protection method is compatible with fixed-wing and vertical take-off and landing UAVs. The protective structure is lightweight and integrated, without requiring any changes to the original aerodynamic layout, flight control system, and payload installation structure of the UAV. After continuous irradiation test with 20kV / m high field strength microwaves across the 1~18GHz full frequency band, the shielding effectiveness of the UAV as a whole is stable at ≥40dB, and there are no crashes, signal interruptions, or device breakdowns in the flight control, navigation, and data transmission systems.

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