Optimization method and evaluation method for electromagnetic shielding of fuselage of unmanned aerial vehicle

Abstract

The invention provides an unmanned aerial vehicle body electromagnetic shielding evaluation method, which belongs to the technical field of unmanned aerial vehicle electromagnetic shielding, and comprises the following steps: constructing a shielding attenuation calculation model according to the thickness and relative conductivity of a shielding structure, and analyzing the attenuation of electromagnetic shielding of materials with different thicknesses; the material thickness of the unmanned aerial vehicle fuselage shielding structure is adjusted according to the attenuation analysis result; an energy self-adaptive surface is constructed, a periodic grid structure is constructed to realize selective shielding of incident waves, and selective shielding effects of different materials are analyzed; and shielding the effect according to the selectivity. The method has the advantages that the content of high-frequency electromagnetic waves is concerned and focused on screening of shielding objects in the use environment of the unmanned aerial vehicle, the shielding effect of the electromagnetic shielding mechanism of the unmanned aerial vehicle for each frequency domain can be accurately judged through frequency domain shielding effect evaluation, optimization for weak frequency domains is facilitated, and a frequency domain optimization direction is provided.

Description

Technical Field

[0001] The present invention belongs to the technical field of electromagnetic shielding of unmanned aerial vehicles, and in particular relates to an optimization method and an evaluation method for electromagnetic shielding of a drone body. Background Art

[0002] With the continuous improvement of the intelligence, automation and information sharing level of power inspection of transmission lines, as well as the development of multiple intelligent technologies such as wireless positioning technology and remote sensing technology. UAVs not only have the advantages of small size, good maneuverability, easy control, no personnel safety risk, no influence of terrain and region, a wide range of models and sensors, the ability to hover and take pictures at any position, more comprehensive and diverse data collection, low inspection cost, and low maintenance cost, but also have a unique functional platform and operating efficiency, which can realize close-range detection of equipment, and its flexible movement mode enables UAVs to inspect visual blind spots on the ground. Therefore, UAVs have become an important supplement to the power inspection system and have been rapidly promoted and applied.

[0003] However, in high-voltage direct current transmission projects, the rapid triggering and shutting down of the thyristors during the operation of the converter valves will generate high voltage and current change rates in the circuit, causing strong electromagnetic interference. In addition, the corona and sparks generated by the high-voltage equipment in the converter station, as well as the impact voltage caused by operation, lightning, and faults, will all generate strong electromagnetic interference, which may cause the inspection drone to fail to work properly.

[0004] Therefore, when using drones to work in converter stations, the electromagnetic shielding performance of the drone body should be optimized and evaluated. Summary of the invention

[0005] The technical problem to be solved by the present invention is the interference of external magnetic fields on electromagnetic signals of drones. In view of the shortcomings of the prior art, an optimization method and an evaluation method for electromagnetic shielding of a drone body capable of shielding external magnetic fields are provided. To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0006] A shielding attenuation calculation model was built based on the thickness and relative conductivity of the shielding structure to analyze the attenuation of electromagnetic shielding of materials with different thicknesses.

[0007] adjusting the material thickness of the shielding structure of the UAV fuselage according to the attenuation analysis results;

[0008] Construct energy-adaptive surfaces, build periodic grid structures to achieve selective shielding of incident waves, and analyze the selective shielding effects of different materials;

[0009] According to the selective shielding effect, a frequency domain shielding network is constructed by alternately adding different materials through the UAV fuselage shielding structure;

[0010] The UAV fuselage shielding structure is optimized based on the cost and selective shielding effects of different material thicknesses and the frequency domain shielding network.

[0011] Furthermore, a shielding attenuation calculation model is constructed according to the thickness and relative conductivity of the shielding structure. The method for analyzing the attenuation of electromagnetic shielding of materials with different thicknesses includes:

[0012] The electromagnetic shielding method is divided into electromagnetic wave absorption and reflection. The attenuation of electromagnetic shielding materials after electromagnetic shielding is calculated and analyzed. The thickness of the shielding layer is adjusted to obtain the absorption attenuation of materials with different thicknesses. The material of the metal material is adjusted according to its relative conductivity to obtain multiple reflection attenuation and reflection attenuation. The evaluation variable of the shielding effectiveness is SE, which is expressed in decibels (dB). Its definition includes:

[0013] SE = R + A + B;

[0014] Where: A is absorption attenuation, B is multiple reflection attenuation, R is reflection attenuation, and the absorption attenuation calculation method includes:

[0015]

[0016] The multiple reflection attenuation calculation method includes:

[0017]

[0018] Reflection attenuation calculation methods include:

[0019]

[0020] Where, t is the thickness of the metal plate (mm), f is the frequency of the electromagnetic wave, σ r is the relative conductivity, μ r is the relative magnetic permeability, Z is the air wave impedance, Z s is the metal wave impedance (Ω).

[0021] Furthermore, the method of constructing an energy adaptive surface and building a periodic grid structure to achieve selective shielding of incident waves includes:

[0022] Metal conductor units and impedance adaptive units are used to construct an energy adaptive surface, a periodic grid structure is built, and the impedance is adjusted in the energy domain to selectively shield the incident wave;

[0023] Assuming that the electromagnetic wave is incident on the surface of an infinite lossy medium, the external field strength of the lossy medium is used as the basis for analysis. Assuming that the internal field distribution of the lossy medium is zero, the transmission line equivalent model is used for analysis:

[0024] The method for obtaining the transmission coefficient Tv of the voltage on the transmission line includes:

[0025]

[0026] Among them, the surface impedance of the electromagnetic protection material changes with the external field strength, and is expressed as low pass and high resistance in the energy domain;

[0027] The electric field transmission coefficient T on the surface of an infinite lossy dielectric E The acquisition methods include:

[0028]

[0029] In which, the electric field strength is assumed to be E i The electromagnetic wave is incident on the infinite lossy dielectric surface, and the electric field strengths of the reflected wave and the transmitted wave are E r and E t ; Y0 is the characteristic admittance, Y1 is the resistance of the parallel admittance on the infinitely long transmission line of Y0, V i is the incident traveling wave voltage, V r is the reflected wave voltage at Y1, V t is the voltage of the wave that continues to be transmitted through Y1; Z1 is the surface impedance of the lossy medium surface, and η is the wave impedance in the air.

[0030] Further, according to the selective shielding effect, the method of constructing a frequency domain shielding network by alternately adding different materials to the UAV fuselage shielding structure includes:

[0031] The electromagnetic shielding structure is set to high-conductivity materials and high-magnetic-permeability materials of different materials for electromagnetic simulation, and the electromagnetic simulation results of high-conductivity materials and high-magnetic-permeability materials in different frequency domains are obtained;

[0032] The electromagnetic shielding structure is set to alternately apply high-conductivity material and high-magnetic-permeability material, and then electromagnetic simulation is performed to obtain the electromagnetic simulation results of high-conductivity material and high-magnetic-permeability material in different frequency domains.

[0033] Furthermore, the UAV fuselage shielding structure includes:

[0034] The shielding shell comprises a shell and a bottom plate, the shape of the bottom plate is designed according to the shape of the lower main structure plate of the drone, the surface of the shell is provided with a shell cover for accommodating the motor arm of the drone, and the top of the shell is provided with a hole for the antenna to pass through.

[0035] Furthermore, the UAV fuselage shielding structure also includes that a high electrical conductivity material layer and a high magnetic permeability material layer are provided on the surface of the shielding shell, and the high electrical conductivity material and the high magnetic permeability material are alternately applied to the surface of the shielding shell.

[0036] A method for evaluating electromagnetic shielding of an unmanned aerial vehicle fuselage, comprising:

[0037] Obtain the shielding attenuation of the electromagnetic shielding structure of the UAV fuselage;

[0038] Construct a three-dimensional model of the drone fuselage shielding structure based on the actual size of the drone;

[0039] Using a simulation platform to mesh the model and add an electromagnetic wave physical field, and performing electromagnetic simulation on the model in the electromagnetic wave physical field;

[0040] Model simulation technology is used in the frequency domain and direction to verify the shielding effect of the UAV fuselage shielding structure and obtain the shielding effectiveness of the electromagnetic shielding.

[0041] Furthermore, the method for obtaining the shielding attenuation of the electromagnetic shielding structure of the UAV fuselage includes:

[0042] The shielding effect is measured proportionally:

[0043]

[0044] E1 and E2 are the electric field strengths measured before and after shielding, respectively.

[0045] Furthermore, the shielding effect of the UAV fuselage shielding structure is verified by using the model simulation technology and the shielding attenuation calculation model in the frequency domain, and the method for obtaining the shielding effectiveness of the electromagnetic shielding includes:

[0046] Frequency domain simulation, taking nodes at intervals in different frequency domains to carry out simulation, calculating the evaluation variables of the shielding effectiveness of the shielding structure at the nodes according to the shielding attenuation calculation model, and after multiple simulations, obtaining the signal shielding effect of the shielding structure in different frequency domains according to the evaluation variables of the shielding effectiveness.

[0047] Furthermore, the method of using the model simulation technology and the shielding attenuation calculation model to verify the shielding effect of the UAV fuselage shielding structure in the direction and obtain the shielding effectiveness of the electromagnetic shielding includes:

[0048] Direction simulation: In the simulation platform, the bottom surface of the UAV shell facing the interference source is defined as the normal posture, and the longest surface of the shielding shell facing the interference source is defined as facing the interference source. By setting the rotation angle of the three-dimensional model to simulate different postures of the UAV, simulation tests are performed to obtain the electric field strength of the UAV body before and after shielding, and finally the electromagnetic shielding effectiveness.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] 1. In terms of frequency domain evaluation, by constructing a shielding attenuation calculation model, the shielding effectiveness of the electromagnetic shielding is obtained to obtain the shielding characteristics under different frequencies. It is concluded that the reflection attenuation R is the main factor at low frequencies, and the absorption attenuation A is the main factor at high frequencies. The main reason is that the shielding effect decreases slightly with increasing frequency. Under the premise that electromagnetic waves are basically shielded, the high-frequency electromagnetic waves that are easy to pass through holes due to their short wavelength have a more prominent impact on the shielding results. Combined with the fact that the frequency of receiving instructions for drones is generally high, the screening of shielding objects in the drone use environment can focus on the content of high-frequency electromagnetic waves and focus on them. Through the frequency domain shielding effect evaluation, the shielding effect of the drone electromagnetic shielding mechanism for each frequency domain can be accurately judged, which is convenient for optimizing weak frequency domains and providing frequency domain optimization direction.

[0051] 2. In terms of directional evaluation, the shielding effect is best when the longest surface is facing the electromagnetic wave. As the rotation angle increases from 0 to 90 degrees, the shielding effect becomes worse and worse, and the higher the frequency, the greater the decline. The main reason is that as the rotation angle increases, electromagnetic waves can more conveniently enter the shielding shell through the holes opened for the motor arm to extend. The shielding effect is worst when the longest surface is facing the electromagnetic wave sideways. This evaluation method can understand the shielding effect of the electromagnetic shielding structure in all directions, so that in actual usage scenarios, the flight route can be properly planned according to this feature to reduce the chance of side facing and maintain the electromagnetic shielding effect, or the overall shielding effect can be improved by strengthening the shielding of weak areas, providing different surface-to-structure optimization directions. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0053] Figure 1 : A schematic structural diagram of a shielding shell model in Embodiment 1 of the present invention;

[0054] Figure 2 : A schematic structural diagram of an assembly model consisting of a drone and a shielding shell in Example 1 of the present invention;

[0055] Figure 3 : Schematic diagram of the simulation area in Example 3 of the present invention;

[0056] Figure 4 : A schematic diagram of the grid division of the simulation area in Example 3 of the present invention;

[0057] Figure 5 : A schematic diagram of the surface grid of the shielding shell in Example 3 of the present invention;

[0058] Figure 6 : A schematic diagram of the radiation pattern of the shielding shell in Embodiment 3 of the present invention;

[0059] Figure 7 : A schematic diagram of the position of the ventilation holes in Example 3 of the present invention;

[0060] Figure 8 : Schematic diagram of the path of the horizontal component in various holes in Example 3 of the present invention;

[0061] Fig. 9 : Schematic diagram of 100MHz simulated electromagnetic shielding in Example 1 of the present invention;

[0062] Fig.10 : A schematic diagram of a line graph of the shielding effectiveness of the shielding shell when electromagnetic waves of different frequencies are directed toward the shielding shell in Example 3 of the present invention;

[0063] Fig.11 : Schematic diagram of the energy adaptive surface structure in Example 1 of the present invention;

[0064] Fig.12 : Equivalent schematic diagram of the transmission line in Example 1 of the present invention. DETAILED DESCRIPTION

[0065] In order to better understand the present invention, the content of the present invention is further clearly described below in conjunction with the embodiments and the accompanying drawings, but the protection content of the present invention is not limited to the following embodiments. In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details.

[0066] Electromagnetic interference is composed of three elements: interference source, interference path, and interfered object. In the electromagnetic interference process of drones, these interference sources cannot be shielded or eliminated, and the electromagnetic influence they produce will exist for a long time. Since it cannot be eliminated from the root, the electromagnetic interference protection measures of drones are divided into two aspects: cutting off the propagation path and strengthening the electromagnetic protection of the interfered object itself. Among them, the former mainly uses shielding technology to suppress the propagation of electromagnetic interference, and then cut off its coupling path; the latter refers to setting up circuits inside the drone to achieve the effect of electromagnetic protection, which is mainly divided into grounding technology, filtering technology and isolation technology. Grounding technology refers to the use of reasonable methods such as analog ground, signal ground, and digital ground to determine the reference potential to suppress the electromagnetic interference generated by capacitive-inductive-resistive coupling; filtering technology is to filter out electromagnetic interference energy through various filters such as bandpass filters, ferrite magnetic ring filters, and power supply filters; isolation technology mainly uses isolation components such as optocouplers, surface acoustic wave filters, and isolation transformers to achieve the purpose of separating protection circuits and interference sources;

[0067] like Figure 1As shown, shielding technology actually uses shielding materials to form a shielding layer to wrap the protected equipment, and then reflect or absorb electromagnetic waves in the environment to eliminate interference. Common shielding materials are divided into three categories: metal materials represented by iron, aluminum, zinc, and copper; conductive polymer materials including composite and intrinsic types; soft electromagnetic shielding materials represented by copper-nickel cloth, conductive mesh, and conductive sponge. The electromagnetic coupling of drones mainly includes two forms: "front door" coupling and "back door" coupling. The coupling method of electromagnetic energy through antennas and transmission cables to the electronic equipment inside the system is called "front door" coupling, and the coupling of electromagnetic energy through holes and seams on the body is called "back door" coupling. These main parts need to be electromagnetically shielded to protect the circuit system.

[0068] Embodiment 1: A method for optimizing electromagnetic shielding of a drone fuselage according to this embodiment comprises: S1, constructing a shielding attenuation calculation model according to the thickness and relative conductivity of the shielding structure, and analyzing the attenuation of electromagnetic shielding of materials with different thicknesses; adjusting the material thickness of the drone fuselage shielding structure according to the attenuation analysis results;

[0069] The electromagnetic shielding method is divided into electromagnetic wave absorption and reflection. The attenuation of electromagnetic shielding materials after electromagnetic shielding is calculated and analyzed. The thickness of the shielding layer is adjusted to obtain the absorption attenuation of materials with different thicknesses. The material of the metal material is adjusted according to its relative conductivity to obtain multiple reflection attenuation and reflection attenuation. The evaluation variable of the shielding effectiveness is SE, which is expressed in decibels (dB) and is defined as follows:

[0070] SE = R + A + B;

[0071] Among them: A is absorption attenuation, B is multiple reflection attenuation, R is reflection attenuation. For metal materials, the absorption attenuation calculation method is as follows:

[0072]

[0073] The multiple reflection attenuation is calculated as follows:

[0074]

[0075] The reflection attenuation is calculated as follows:

[0076]

[0077] Where, t is the thickness of the metal plate (mm), f is the frequency of the electromagnetic wave, σ r is the relative conductivity (copper σ r =1), μ r is the relative magnetic permeability (copper μ r =1), Z is the air wave impedance, Z s is the metal wave impedance (Ω).

[0078] A brief introduction to shielding materials begins with traditional metal shielding materials. This type of hard material is generally a solid structure, and its shielding principle is that the movement of free electrons makes it highly conductive and highly permeable. At present, iron, aluminum, zinc, copper, etc. are usually made into alloy materials to improve their strength, hardness, ductility and corrosion resistance, and can also be made into coatings to improve their conductivity in combination with other materials. The highly-regarded polymer materials contain abundant carriers, which flow or jump between chains, giving the materials good conductivity. In addition, this type of material generally adopts a cellular structure, which has the advantages of light weight, low cost, and corrosion resistance. At present, carbon fiber materials are mainly used in the field of drones. The shielding materials used in the fuselage are mainly the above two types, and conductive paint is usually sprayed on the surface. The commonly used coating material is ferrite. There are also some key protected areas in drones, such as the electromagnetic sealing gaskets used at the joints of the fuselage panels and covers, which are generally made of conductive rubber and beryllium copper finger-shaped springs; ventilation and cooling holes need to consider both shielding and ventilation requirements, and volume, dustproofing, quality and other aspects must also be taken into account. Metal filters (steel, aluminum, foamed metal) are generally installed at the ventilation windows; the display window needs to be both light-transmitting and shielding, and generally metal mesh sandwich heated glass, organic conductive film or foamed metal light-transmitting plate are used to meet the requirements.

[0079] The electromagnetic shielding materials of drones still have some deficiencies in terms of hard conditions. For example, the weight and volume of shielding materials represented by metals are too large, which does not meet the characteristics of lightweight flight of drones. Drones made of carbon fiber composite materials are light in weight and high in strength. The composite shielding solution of carbon fiber composite materials and metal coatings can better meet the requirements of lightweight drones.

[0080] S2, construct an energy-adaptive surface, build a periodic grid structure to achieve selective shielding of incident waves, and analyze the selective shielding effects of different materials:

[0081] Energy adaptive surface uses periodic grid structure to achieve selective shielding of incident waves. Energy adaptive surface is composed of "metal conductor unit" and "impedance adaptive unit" to build a periodic grid structure to achieve selective shielding of incident waves, and achieve "selective shielding" in "energy domain" by adjusting impedance, such as Fig.11 shown.

[0082] Energy selective surface is a protective material that can change its electromagnetic properties according to the magnitude of the incident electromagnetic wave field strength. When electromagnetic waves are incident on an infinite lossy dielectric surface, if we only care about the external field strength of the lossy dielectric and do not need to consider the internal field distribution of the lossy dielectric, we can use the transmission line equivalent model for qualitative analysis, such as Fig.12 As shown;

[0083] Therefore, the transmission coefficient Tv of the voltage on the transmission line is:

[0084]

[0085] The electric field transmission coefficient TE on the surface of an infinite lossy dielectric is:

[0086]

[0087] In it, an electromagnetic wave with an electric field intensity of Ei is incident on an infinite lossy dielectric surface, and the electric field intensities of the reflected wave and the transmitted wave are Er and Et respectively;

[0088] Simulation equivalent circuit: a resistor with a parallel admittance of Y1 is connected to an infinitely long transmission line with a characteristic admittance of Y0. The incident traveling wave voltage is Vi, the reflected wave voltage at Y1 is Vr, and the voltage of the wave that continues to be transmitted through Y1 is Vt.

[0089] Among them, Z1 is the surface impedance of the lossy dielectric surface, and η is the wave impedance in the air. From the calculation formula of the electric field transmission coefficient of the infinite lossy dielectric surface, it can be seen that when the surface impedance of the lossy dielectric surface is smaller, its shielding effect is better, and vice versa.

[0090] Therefore, if the surface impedance of the electromagnetic protection material can change with the strength of the external field, the "low-pass and high-resistance" transmission characteristics in the energy domain can be achieved.

[0091] S3, according to the selective shielding effect, alternately adding different materials through the UAV fuselage shielding structure to construct a frequency domain shielding network; according to the cost and the selective shielding effect of different material thicknesses and the frequency domain shielding network, optimizing the UAV fuselage shielding structure;

[0092] The electromagnetic shielding structure is set to high-conductivity materials and high-magnetic permeability materials of different materials for electromagnetic simulation, and the electromagnetic simulation results of high-conductivity materials and high-magnetic permeability materials in different frequency domains are obtained; according to the shielding attenuation formula in the previous article, it can be known that electromagnetic shielding materials actually have two elements, namely conductivity and magnetic permeability, so we can explore which high-conductivity material and high-magnetic permeability material are more suitable for electromagnetic shielding in this case. And the number of layers of shielding materials affects the shielding effect. The following will focus on these two issues for simulation, and choose the 100MHz longest face as the common condition.

[0093] First, the high magnetic permeability materials in reality, such as iron-nickel alloy, have a relative magnetic permeability of 4000, but at the same time, they also have an electrical conductivity of 2E6S / m. We simulated it first and found that the simulated waveform was exactly the same as the waveform of copper, and the influence of electrical conductivity could not be ruled out. In order to control the variables, we changed the relative magnetic permeability of the material to 5.998E7 and the electrical conductivity to 1S / m, and then conducted the experiment. The high magnetic permeability materials mentioned below all refer to this material;

[0094] As shown in Table 3.3, although the electric field mode inside the shielding shell is close to 0, spike waveforms appear on both sides, and the intensity is even higher than before. It is speculated that this is because the reflection attenuation at this time is a negative value, resulting in rebound.

[0095] After actual measurement, the thickness of a single layer of copper is 0.02mm, so the thickness is changed to 0.04mm to simulate the situation of double-layer high conductivity, and its waveform shape is exactly the same as that of a single layer of copper;

[0096] The electromagnetic shielding structure is set to alternately apply high-conductivity materials and high-magnetic-permeability materials, and then electromagnetic simulation is performed to obtain the electromagnetic simulation results of high-conductivity materials and high-magnetic-permeability materials in different frequency domains:

[0097] The double-layer high magnetic permeability still has a peak phenomenon of amplitude rebound. The electromagnetic permeability is consistent with the shape of single and double conductance, so the high conductivity material can avoid the peak phenomenon caused by negative reflection attenuation. The shielding effect at 2m is further compared (the high conductivity material is copper, and the high magnetic permeability material is a self-modified material, so there is no actual correspondence):

[0098] Table 3.3 Shielding effectiveness of different materials and number of layers (100MHz, facing)

[0099]

[0100] It can be seen that the shielding performance of high magnetic permeability materials under this frequency condition is obviously not as good as that of high electrical conductivity materials. They are more suitable for shielding low-frequency magnetic fields. Therefore, the method of alternating high magnetic permeability materials can be used in situations where the shielding object contains low-frequency magnetic fields. In terms of the number of layers, the shielding effect is significantly improved with the increase in the number of layers of high magnetic permeability materials. It is speculated that the magnetic saturation problem has been improved, while there is no obvious change with the increase in the number of layers of high electrical conductivity materials. Therefore, converter stations with main electromagnetic interference of 20kHz-30MHz electromagnetic waves are more suitable for shielding with high electrical conductivity materials, and a single layer can achieve good results.

[0101] Beneficial effects:

[0102] 1. By analyzing the attenuation frequency domain shielding effect evaluation of electromagnetic shielding of materials with different thicknesses, it is possible to accurately judge the shielding effect of the electromagnetic shielding mechanism of the UAV for each frequency domain, so as to optimize the weak frequency domain and provide the frequency domain optimization direction;

[0103] 2. High magnetic permeability materials are more suitable for shielding low-frequency magnetic fields. In the converter station environment, the shielding effect is not as good as that of high electrical conductivity materials. In terms of the number of layers, increasing the number of layers of high magnetic permeability materials improves the magnetic saturation problem, thereby significantly improving the shielding effect, but increasing the number of layers of high electrical conductivity materials has no significant change. Therefore, converter stations with main electromagnetic interference of 20kHz-30MHz electromagnetic waves are more suitable for shielding with high electrical conductivity materials, and a single layer can achieve a good effect.

[0104] 3. By alternately adding different materials to the UAV fuselage shielding structure, a frequency domain shielding network is constructed. The high electromagnetic permeability alternating coating method is more suitable for use in situations where the shielding object includes a low-frequency magnetic field, providing an optimization direction for the superposition of different materials.

[0105] Embodiment 2: An electromagnetic shielding structure for a drone fuselage is completed based on the optimization method for electromagnetic shielding of a drone fuselage as described in Embodiment 1. The drone fuselage shielding structure comprises: a shielding shell, the shielding shell comprises a shell and a bottom plate, the shape of the bottom plate is designed according to the contour of the lower main structure plate of the drone, the contour design means that the main board has the same shape as the lower main structure plate, and the size is slightly larger than the main structure plate, and the part larger than the main structure plate is used to install the shell, the surface of the shell is provided with a shell cover for accommodating the drone motor arm, the contoured shielding shell provided according to the drone structure can better adapt to the drone, and the space optimization effect is better, and the top of the shell is provided with a hole for the antenna to pass through;

[0106] The UAV fuselage shielding structure also includes that a high electrical conductivity material layer or a high magnetic permeability material layer is provided on the surface of the shielding shell;

[0107] The UAV fuselage shielding structure also includes that a high-conductivity material layer and a high-magnetic-permeability material layer are arranged on the surface of the shielding shell, and the high-conductivity material and the high-magnetic-permeability material are alternately applied to the surface of the shielding shell.

[0108] Embodiment 3: A method for evaluating electromagnetic shielding of a drone fuselage, used to evaluate the optimization effect of an existing drone fuselage or a method for optimizing electromagnetic shielding of a drone fuselage as described in the embodiment, comprising: Y1, obtaining the shielding attenuation of the electromagnetic shielding structure of the drone fuselage;

[0109] The shielding attenuation is obtained based on the electric field strength before and after shielding, and the shielding effect is measured using a proportional formula:

[0110]

[0111] E1 and E2 are the electric field strengths measured before and after shielding, respectively.

[0112] Y2, build a three-dimensional model of the UAV fuselage shielding structure based on the actual size of the UAV;

[0113] 1) Drone parameters

[0114] The research object is the DJI Mavic 3 drone, whose main structure is shown in the figure below. Specifically, it includes the upper and lower main structural plates, the main control unit, the remote control transceiver unit, 4 motors, propellers and arms, the GPS bracket and its receiver, batteries, etc. There is also a suspension platform and 2 legs under the fuselage.

[0115] Its important working parts such as circuit boards, main control, remote control transceiver unit, etc. are all exposed to the air, which will be subject to very fatal interference in a complex electromagnetic environment. Therefore, in order to make an electromagnetic shielding shell, a vernier caliper was used to measure the size parameters of each part. The results are shown in the table below.

[0116] (1) UAV fuselage modeling

[0117] According to the above parameters, the drone is modeled in SolidWorks 2021. Since the lower motherboard of the drone is the core structure of the drone and basically all important structures are connected by it, its sketch is drawn first. To ensure the accuracy of this step, the position of each screw hole, the length of each edge and the angle between them should be further measured.

[0118] This surface is the reference surface of the UAV, and operations such as stretching, shelling, cutting, and rotation are performed on its basis to arrange the relative positions of blades, motor arms, suspension platforms, legs and other parts.

[0119] (2) Modeling of UAV shielding shell

[0120] The shield shell is designed based on the UAV model and the research of the research team, still starting from the core part, that is, the lower main structure plate of the UAV. The modeling idea is to create a base plate slightly larger than the lower main structure plate of the UAV, ensuring that the two are basically fitted while leaving a certain space for extension to combine with the upper shell. The upper shell is formed by stretching and drawing the shell based on the lower base according to the height of each part of the UAV. In order to meet the characteristics of the UAV's lightweight flight, its thickness is only 2.18mm.

[0121] like Figure 1-2As shown, it can be seen that 4 rectangular holes are opened around the shielding shell, which are slightly larger than the motor arm of the drone, so that it can be extended out of the shell. The semicircular hole in the front is designed for the antenna of the remote control transceiver, and the long hole on the top is to reserve space for the GPS bracket. The research team has designed the basic shape before, but sharp corners are used on the upper surface and sides. Sharp corners will hinder the conduction of force, so that force accumulates at the sharp corners, which can easily cause corner cracks. Rounded corners can transmit force, reduce stress concentration, and play a role in strengthening strength. The rounded corner structure can also guide airflow and reduce wind resistance, so the original model has been optimized to a certain extent. The upper surface and sides are rounded with a radius of 2mm. The six screw holes around and on both sides play a fixing role during installation. It can be seen that the main part of the drone has been covered by the shielding shell and is no longer directly exposed to complex environments.

[0122] Y3, using a simulation platform to perform meshing on the model and add electromagnetic wave physical fields, and perform electromagnetic simulation on the model in the electromagnetic wave physical fields;

[0123] 1) Simulation settings

[0124] The simulation platform selected is COMSOL Multiphysics 6.0, which is the finite element simulation software that comes with the new version of the modeling platform SolidWorks. It may be relatively niche, but the interface is simple and easy to use. From component modeling, meshing, physical field addition, solver configuration, etc., you can integrate it yourself, and it has a commonly used material library, and the result data processing methods are very rich. The software has an electromagnetic wave physics field, which is very suitable for the research needs of electromagnetic shielding technology.

[0125] like Figure 3 As shown in the figure, the designed UAV shielding shell is imported from SolidWorks into this software. Since the interference source in reality is at a certain distance from the UAV, a rectangular area of ​​5*0.2*0.2 (unit: m) is set as the simulation area, which is filled with air. The main body of the shielding shell placed in the center of the area is made of nylon material, and the inside is coated with copper conductive paint. The interference source is at the left port of the entire area.

[0126] like Figure 4-5 As shown, mesh division needs to take both simulation speed and simulation accuracy into consideration. After comprehensive comparison, mesh division with a finer degree of refinement is selected. The mesh is automatically generated according to the size, so the mesh on the surface of the shielding shell is finer, so that the result is not too slow and has a certain degree of accuracy.

[0127] The main simulation scenario is set as follows: electromagnetic waves of a certain frequency are introduced from one side of the simulation area. The electromagnetic waves emitted will pass through the shielding shell. A line passing through the center of the shielding shell and parallel to the x-axis is taken as the research line. The field strength mode along the x-axis on this research line is plotted to compare the field strength inside and outside the shielding shell and evaluate its shielding effect. The research is mainly carried out from four aspects: frequency domain, direction, material and number of layers, and number and shape of holes.

[0128] Y4, using model simulation technology in frequency domain, direction and opening to verify the shielding effect of the UAV fuselage shielding structure and obtain the shielding effectiveness of the electromagnetic shielding;

[0129] 1) Frequency domain simulation

[0130] In the frequency domain, nodes are selected at intervals in different frequency domains for simulation, and the evaluation variables of the shielding effectiveness of the shielding structure at the nodes are calculated according to the shielding attenuation calculation model. After multiple simulations, the signal shielding effect of the shielding structure in different frequency domains is obtained according to the evaluation variables of the shielding effectiveness.

[0131] As mentioned above, the background setting is an S500 drone operating in a converter station. There is a large interference level of more than 100dB in the range of 20kHz-30MHz in the converter station. The operating frequency of this type of drone is 433MHz, so the interference near this frequency is most likely to cause confusion to the drone's signal reception and should also be paid attention to. Therefore, nodes are appropriately spaced in the frequency domain of 10kHz-1GHz for simulation. First, take 100MHz as an example for analysis. The wavelength at this frequency is 3m. The simulation results are as follows: Fig. 9 As shown;

[0132] Directly facing means that the longest side of the shielding shell is facing the interference source, which will be specifically indicated in the research direction later. It can be seen that since the metal will completely reflect the electromagnetic wave, the result shows a steady-state phenomenon, so the wave and the reflected wave are superimposed to form a standing wave, and the frequency remains unchanged. The ordinate in the figure is the electric field modulus, so the result is an absolute value. A careful observation will reveal that the trough is in the shape of a spike, so the actual wavelength is still 3m, not 1.5m. This phenomenon will not be explained later. The abscissa is the original x-coordinate plus 2m, so the center of the shielding shell is at 2m. The place where the middle electric field modulus is close to 0 is the range of the shielding shell. In order to verify whether this research area is reasonable, it is appropriately reduced to 4*0.2*0.2 (unit: m), and the results are observed, and then doubled, that is, 10*0.2*0.2 (unit: m).

[0133] The result of the 4m long area is different from that of the 5m long area, but the results of the 5m long area and the 10m long area are consistent, so it can be extended to an infinite area, that is, the area size is reasonable. Qualitative analysis shows that the shielding effect is good, and 100MHz electromagnetic waves basically cannot enter the inside of the shielding shell. The qualitative analysis point is the center of the shielding shell, that is, 2m. It can be observed from the direction of the sine wave that its value is 0.260V / m when it is not shielded. After amplification, the value recorded at 2m is 9.865E-5V / m. The shielding effect under this condition can be calculated according to the formula:

[0134]

[0135] Then reduce the frequency to 50MHz and calculate the shielding effect according to the formula:

[0136]

[0137] It can be seen that the shielding effect is slightly improved. Then the frequency is reduced to 10MHz. At this time, the wavelength is relatively large compared to the simulation range, so the wave number is very limited. The shielding effect is also calculated according to the formula:

[0138]

[0139] In the three simulation results at this time, although the intensity of the electromagnetic wave inside the shielding shell is close to 0, the intensity on both sides of the shielding shell does not change when it leaves the shielding shell and enters the shielding shell. It can be concluded that the lower frequency band is mainly reflected attenuation R. The results of other low-frequency bands such as 10kHz, 1MHz and other low-frequency bands will not be repeated. The data will be presented in the form of tables and line graphs later. The frequency is increased to 300MHz on the basis of 100MHz, and the simulation results are as follows:

[0140] The shielding effect is calculated according to the formula:

[0141]

[0142] The shielding effect has decreased a little. Then the frequency is increased to 500MHz. The shielding effect is calculated according to the formula:

[0143]

[0144] Although the shielding effect is still decreasing, the electric field modulus of the electromagnetic wave leaving the shielding shell is significantly lower than when entering, and the synthetic standing wave node is not near 0, indicating that the amplitude of the reflected wave is different from that of the incident wave. It can be seen that in addition to the reflection attenuation R, there is also a lot of absorption attenuation A. Then increase the frequency to 750MHz, and the results are as follows:

[0145] The shielding effect is also calculated according to the formula:

[0146]

[0147] At this time, it is obvious that absorption attenuation A occupies a dominant position, and the difference between the electromagnetic wave before and after passing through the shielding shell is more significant. In addition, the frequencies above 100MHz such as 433MHz, 600MHz, 1GHz, etc. are not repeated here, and generally conform to the above rules. The results of the frequency domain study are plotted into a table as follows:

[0148] Table 3.1 Shielding effectiveness of shielding shells facing electromagnetic waves of different frequencies

[0149]

[0150]

[0151] Make the results into a line graph, such as Fig.10 As shown;

[0152] Conclusion: The shielding effect is very good, even the worst shielding effect reaches 60dB. At low frequencies, the reflection attenuation R is the main factor, and at high frequencies, the absorption attenuation A is the main factor. It is speculated that the reason why the shielding effect decreases slightly with the increase of frequency is that under the premise that electromagnetic waves are basically shielded, the high-frequency electromagnetic waves that are easy to pass through the holes due to their short wavelength have a more prominent impact on the shielding results. Therefore, in the range of 10kHz-1GHz, the shielding effect will decrease slightly as the frequency of electromagnetic waves increases.

[0153] 2) Direction simulation

[0154] In the simulation platform, the bottom surface of the UAV shell facing the interference source is defined as the normal posture, and the longest surface of the shielding shell facing the interference source is defined as facing the interference source. By setting the rotation angle of the three-dimensional model to simulate the different postures of the UAV, simulation tests are performed to obtain the electric field strength of the UAV body before and after shielding, and finally the electromagnetic shielding effectiveness is obtained. In reality, UAVs need to perform various tasks, so they are in motion most of the time relative to the interference source, which requires the shielding shell to have a certain shielding effect on electromagnetic interference from all directions. In view of the symmetry of the UAV and the shielding shell, a quarter of its volume is taken as the research object, and it is checked from four typical directions to find out the weak links of electromagnetic shielding and take corresponding measures to improve it.

[0155] like Figure 6As shown in the figure, the interference source mentioned in the frequency domain simulation above is directly facing the longest side of the shielding shell. It is easy to analyze that because the shielding material is spread out in the largest area at this directly facing angle and the hole is at a larger angle with the area where the electromagnetic waves are most concentrated, it can be seen that when other conditions are the same, the directly facing angle has the best shielding effect. Rotate it 60 degrees to get the longest side 60 degrees facing the interference source. At this time, there is a hole opening in the same direction as the area where the electromagnetic waves are most concentrated; rotate it 30 degrees again to make the longest side face the interference source. At this time, the shielding material is the narrowest and there are two holes with a small angle to the concentrated area. In addition, the 45-degree angle between the positive and side is selected as a transition to facilitate the summary of the rules. Therefore, these three typical angles are selected as the control group to comprehensively evaluate the shielding effect of the shielding shell.

[0156] In order to explore the reasons that affect the shielding effect under directional factors, three different frequencies of 100MHz, 50MHz and 10MHz were selected, which can also be used as examples of the influence of complex factors.

[0157] When facing sideways, the shielding area is obviously longer. The longest surface length before is the length of the shielding area, but two peaks will appear obviously inside the shielding shell. It is speculated that the electromagnetic waves that go straight into the shell from a pair of holes on both sides just converge at two points on the center line, so the above phenomenon occurs. The same phenomenon is found when the frequency is reduced.

[0158] The shielding effectiveness calculation in the side-on situation naturally cannot take the smaller value at 2m. Since the peak is actually also inside the shielding shell, according to the short board effect of the wooden barrel, the value at the peak is taken as the electric field modulus after shielding.

[0159] Similarly, the case of the 45-degree slanted pair is also carried out at these three frequencies, and the results are as follows:

[0160] Except for a very small amount of jitter in the waveform at the descending and rising points, the waveform shape at an oblique 45-degree angle does not change much compared to the straight-on waveform. The length of the shielded area is the length of a diagonal line of the non-diagonal line of the rectangle, which is between the straight-on and side-on waveforms.

[0161] The results of the 60-degree slanted pair under three frequency conditions are as follows. Similar to the side pair, two peaks also appear, but it is worth mentioning that the shielding area on the center line is the length of the diagonal line, which is exactly the maximum value during rotation.

[0162] Taking the front direction as the benchmark, the shielding effectiveness at four rotation angles (0 degree, 45 degree, 60 degree, 90 degree) is summarized and compared with the benchmark value to calculate the relative error, in order to summarize the rules under the combined effect of frequency and direction.

[0163] Table 3.2 Shielding effectiveness of electromagnetic waves of three frequencies facing the longest side of the shielding shell in different directions

[0164]

[0165] In general, the shielding effect is best when the longest surface is facing the electromagnetic wave. As the rotation angle increases from 0 to 90 degrees, the shielding effect becomes worse and worse, from about 70dB when facing directly to about 60dB when tilted at 45 degrees to about 50dB when tilted at 60 degrees, and finally to about 30dB when facing sideways. The higher the frequency, the greater the decline. Therefore, it can be inferred that the reason for the significant decline in the shielding effect is that as the rotation angle increases, electromagnetic waves can more easily enter the shielding shell through the holes opened for the motor arm to extend. From 0 to 60 degrees, it corresponds more and more to the opening direction of one of the holes. From 60 to 90 degrees, it keeps a certain correspondence with the original hole while also corresponding more and more to the other hole. The smaller the wavelength, the easier it is for electromagnetic waves to enter. Therefore, the shielding effect is the worst when the longest surface is facing the electromagnetic wave sideways. Based on this, the flight route can be properly planned to reduce the chance of sideways facing.

[0166] 2) Hole shape and quantity simulation

[0167] UAVs need ventilation to dissipate heat during flight, but opening ventilation holes in the shielding shell will obviously reduce its shielding ability. In order to reduce losses while opening ventilation holes, this paper will explore which shape of ventilation holes has the least impact on the shielding effect under the same area, and whether it is necessary to open several small holes instead of one large hole.

[0168] like Figure 7 As shown, in order to form convection, a ventilation hole was opened at the corresponding position on both sides, and the research was still carried out under the condition that the longest surface at 100MHz was facing the interference source. In order to make the difference in the results more obvious, the hole was also located on the longest surface, that is, facing the interference source. Based on the area of ​​the 2mm circular hole, its shape was changed to regular triangle, square, and regular hexagon; the large circle was divided into 2 small circles and 3 small circles with equal area by increasing the number, and the data were obtained by simulation respectively to compare the shielding effect (the inner wall of the hole was also coated with shielding material).

[0169] Since the simulation waveform is completely consistent with the waveform at 100MHz, with only a slight difference in the data, the simulation waveform will not be shown. Instead, the data can be compared. The results are as follows:

[0170] Table 3.4 Shielding effectiveness of holes of different shapes and numbers (100MHz, facing)

[0171]

[0172] like Figure 8As shown, it is obvious that compared with the case without holes, it can be concluded that ventilation holes will weaken the shielding effect. In terms of shape, circle>regular hexagon>square>regular triangle, and in terms of quantity, multiple small ventilation holes are better than a single large ventilation hole. The reasons are as follows: each incident electromagnetic wave is divided into a vertical component and a horizontal component according to the plane where the hole is located. The vertical component determines the time of reflection and absorption on the inner wall of the hole, which is the same for each shape of hole. As for the horizontal component, as shown in the figure below (actually the area is the same, and the height is drawn to be the same for easy observation), since electromagnetic waves can be quickly reflected and absorbed many times at the corners of the hole, the more corners there are, the shorter the average time of each reflection and absorption, and the better the shielding effect (the circle can be regarded as an infinite angle, and multiple can be regarded as angles several times that of a single one). Therefore, under the condition of equal area, circular ventilation holes have the least impact on the shielding effect, and if there is enough space, more small holes can be appropriately opened to replace the large holes with the sum of the areas.

[0173] Beneficial effects:

[0174] 1. In terms of frequency domain evaluation, the shielding effectiveness of electromagnetic shielding is obtained to obtain the shielding characteristics under different frequencies. It is found that reflection attenuation R is the main factor at low frequencies, and absorption attenuation A is the main factor at high frequencies. The main reason is that the shielding effect decreases slightly with increasing frequency. Under the premise that electromagnetic waves are basically shielded, high-frequency electromagnetic waves that are easy to pass through holes due to their short wavelength have a more prominent impact on the shielding results. Combined with the fact that the frequency of receiving instructions for drones is generally high, the frequency domain shielding effect evaluation can accurately judge the shielding effect of the electromagnetic shielding mechanism of the drone for each frequency domain, which is convenient for optimizing weak frequency domains and providing frequency domain optimization direction.

[0175] 2. In terms of directional evaluation, the shielding effect is best when the longest surface is facing the electromagnetic wave. As the rotation angle increases from 0 to 90 degrees, the shielding effect becomes worse and worse, and the higher the frequency, the greater the decline. The main reason is that as the rotation angle increases, electromagnetic waves can more conveniently enter the shielding shell through the holes opened for the motor arm to extend. The shielding effect is worst when the longest surface is facing the electromagnetic wave sideways. This evaluation method can understand the shielding effect of the electromagnetic shielding structure in all directions, so that in actual usage scenarios, the flight route can be properly planned according to this feature to reduce the chance of side facing and maintain the electromagnetic shielding effect, or the overall shielding effect can be improved by strengthening the shielding of weak areas, providing different surface-to-structure optimization directions.

[0176] 3. In terms of ventilation hole evaluation, ventilation holes will weaken the shielding effect. Under the condition of equal area, multiple circular ventilation holes have the least impact on the shielding effect. The reason is that at the corners of the holes, electromagnetic waves can be reflected and absorbed many times very quickly, so the more corners there are, the shorter the average time of each reflection and absorption, and the better the shielding effect. Therefore, in order to heat the drone, circular holes should be opened as much as possible when opening ventilation holes, and if there is enough space, more small holes can be opened to replace large holes with the sum of the areas, so as to avoid a significant decrease in the shielding effect of the shielding shell due to the heat dissipation holes, and provide optimization directions for opening heat dissipation holes.

[0177] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in the field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for optimizing electromagnetic shielding of a drone fuselage, characterized in that: include: A shielding attenuation calculation model was built based on the thickness and relative conductivity of the shielding structure to analyze the attenuation of electromagnetic shielding of materials with different thicknesses. adjusting the material thickness of the shielding structure of the UAV fuselage according to the attenuation analysis results; Construct energy-adaptive surfaces, build periodic grid structures to achieve selective shielding of incident waves, and analyze the selective shielding effects of different materials; According to the selective shielding effect, a frequency domain shielding network is constructed by alternately adding different materials through the UAV fuselage shielding structure; The UAV fuselage shielding structure is optimized based on the cost and selective shielding effects of different material thicknesses and the frequency domain shielding network.

2. The method for optimizing electromagnetic shielding of a drone body as claimed in claim 1, characterized in that: The shielding attenuation calculation model is constructed based on the thickness and relative conductivity of the shielding structure. The methods for analyzing the attenuation of electromagnetic shielding of materials with different thicknesses include: The electromagnetic shielding method is divided into electromagnetic wave absorption and reflection. The attenuation of electromagnetic shielding materials after electromagnetic shielding is calculated and analyzed. The thickness of the shielding layer is adjusted to obtain the absorption attenuation of materials with different thicknesses. The material of the metal material is adjusted according to its relative conductivity to obtain multiple reflection attenuation and reflection attenuation. The evaluation variable of the shielding effectiveness is SE, which is expressed in decibels (dB). Its definition includes: SE = R + A + B; Where: A is absorption attenuation, B is multiple reflection attenuation, R is reflection attenuation, and the absorption attenuation calculation method includes: The multiple reflection attenuation calculation method includes: Reflection attenuation calculation methods include: Where, t is the thickness of the metal plate (mm), f is the frequency of the electromagnetic wave, σ r is the relative conductivity, μ r is the relative magnetic permeability, Z is the air wave impedance, Z s is the metal wave impedance (Ω).

3. The method for optimizing electromagnetic shielding of a drone body as claimed in claim 1, characterized in that: The methods of constructing an energy adaptive surface and building a periodic grid structure to achieve selective shielding of incident waves include: Metal conductor units and impedance adaptive units are used to construct an energy adaptive surface, a periodic grid structure is built, and the impedance is adjusted in the energy domain to selectively shield the incident wave; Assuming that the electromagnetic wave is incident on the surface of an infinite lossy medium, the external field strength of the lossy medium is used as the basis for analysis. Assuming that the internal field distribution of the lossy medium is zero, the transmission line equivalent model is used for analysis: The method for obtaining the transmission coefficient Tv of the voltage on the transmission line includes: Among them, the surface impedance of the electromagnetic protection material changes with the external field strength, and is expressed as low pass and high resistance in the energy domain; The electric field transmission coefficient T on the surface of an infinite lossy dielectric E The acquisition methods include: In which, the electric field strength is assumed to be E i The electromagnetic wave is incident on the infinite lossy dielectric surface, and the electric field strengths of the reflected wave and the transmitted wave are E r and E t ; Y0 is the characteristic admittance, Y1 is the resistance of the parallel admittance on the infinitely long transmission line of Y0, V i is the incident traveling wave voltage, V r is the reflected wave voltage at Y1, V t is the voltage of the wave that continues to be transmitted through Y1; Z1 is the surface impedance of the lossy medium surface, and η is the wave impedance in the air.

4. The method for optimizing electromagnetic shielding of a drone body as claimed in claim 1, characterized in that: According to the selective shielding effect, the method of constructing a frequency domain shielding network by alternately adding different materials to the UAV fuselage shielding structure includes: The electromagnetic shielding structure is set to high-conductivity materials and high-magnetic-permeability materials of different materials for electromagnetic simulation, and the electromagnetic simulation results of high-conductivity materials and high-magnetic-permeability materials in different frequency domains are obtained; The electromagnetic shielding structure is set to alternately apply high-conductivity material and high-magnetic-permeability material, and then electromagnetic simulation is performed to obtain the electromagnetic simulation results of high-conductivity material and high-magnetic-permeability material in different frequency domains.

5. The method for optimizing electromagnetic shielding of a drone body as claimed in claim 1, characterized in that: The UAV fuselage shielding structure comprises: The shielding shell comprises a shell and a bottom plate, the shape of the bottom plate is designed according to the shape of the lower main structure plate of the drone, the surface of the shell is provided with a shell cover for accommodating the motor arm of the drone, and the top of the shell is provided with a hole for the antenna to pass through.

6. The method for optimizing electromagnetic shielding of a drone fuselage according to claim 1, characterized in that: The UAV fuselage shielding structure also includes that a high-conductivity material layer and a high-magnetic-permeability material layer are arranged on the surface of the shielding shell, and the high-conductivity material and the high-magnetic-permeability material are alternately applied to the surface of the shielding shell.

7. A method for evaluating electromagnetic shielding of an unmanned aerial vehicle fuselage, characterized in that: include: Obtain the shielding attenuation of the electromagnetic shielding structure of the UAV fuselage; Construct a three-dimensional model of the drone fuselage shielding structure based on the actual size of the drone; Using a simulation platform to mesh the model and add an electromagnetic wave physical field, and performing electromagnetic simulation on the model in the electromagnetic wave physical field; Model simulation technology is used in the frequency domain and direction to verify the shielding effect of the UAV fuselage shielding structure and obtain the shielding effectiveness of the electromagnetic shielding.

8. The method for evaluating electromagnetic shielding of a drone body as claimed in claim 1, characterized in that: The methods for obtaining the shielding attenuation of the electromagnetic shielding structure of the UAV fuselage include: The shielding effect is measured proportionally: E1 and E2 are the electric field strengths measured before and after shielding, respectively.

9. The method for evaluating electromagnetic shielding of a drone body as claimed in claim 7, characterized in that: The method of verifying the shielding effect of the UAV fuselage shielding structure by using the model simulation technology and the shielding attenuation calculation model in the frequency domain and obtaining the shielding effectiveness of the electromagnetic shielding includes: Frequency domain simulation, taking nodes at intervals in different frequency domains to carry out simulation, calculating the evaluation variables of the shielding effectiveness of the shielding structure at the nodes according to the shielding attenuation calculation model, and after multiple simulations, obtaining the signal shielding effect of the shielding structure in different frequency domains according to the evaluation variables of the shielding effectiveness.

10. The method for evaluating electromagnetic shielding of a drone body according to claim 7, wherein: The method of using the model simulation technology and the shielding attenuation calculation model to verify the shielding effect of the UAV fuselage shielding structure in the direction and obtain the shielding effectiveness of the electromagnetic shielding includes: Direction simulation: In the simulation platform, the bottom surface of the UAV shell facing the interference source is defined as the normal posture, and the longest surface of the shielding shell facing the interference source is defined as facing the interference source. By setting the rotation angle of the three-dimensional model to simulate different postures of the UAV, simulation tests are performed to obtain the electric field strength of the UAV body before and after shielding, and finally the electromagnetic shielding effectiveness.

Images