Lightning protection and wave penetration integrated protection method for aircraft radome and antenna device

Abstract

The application discloses an aircraft radome and antenna equipment lightning protection-wave penetration integrated protection method, steps are: defining lightning partition position; determining lightning environment; modeling the radome and antenna equipment; extracting the structural parameters of the radome and internal metal equipment, determining a preliminary layout scheme; establishing an electrostatic field simulation calculation model, obtaining the influence of lightning protection equipment before and after installation on the electric field intensity distribution inside and outside the radome; establishing an electromagnetic field simulation calculation model, obtaining the influence of lightning protection equipment before and after installation on the antenna performance; performing lightning test; optimizing the electrostatic field simulation calculation model, improving the lightning protection equipment layout; verifying the influence degree of the lightning rod on the antenna performance inside the radome by using different test methods; improving the selection of lightning protection equipment on the surface of the radome; determining the final layout scheme. The application belongs to the technical field of aircraft lightning protection, and lightning protection-wave penetration integration is considered.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lightning protection of aircraft, and relates to an aircraft radome and lightning protection-wave penetration integrated protection method for an antenna device. BACKGROUND

[0002] As a typical extreme environment in nature, lightning seriously threatens the flight safety of surface antenna devices of aviation and aerospace aircraft. The antenna devices are usually arranged on the head and upper and lower surfaces of the aircraft, and the surface of the antenna device is usually covered with a composite material radome for wave penetration and rectification. The antenna device and the radome of the aircraft do not generally have lightning protection function at the beginning of design. When lightning strikes, the high voltage and large current of lightning may cause insulation breakdown of the radome, and then the lightning channel enters the inside of the radome, causing the antenna device containing metal materials to be struck by lightning, thereby causing damage to the front-end antenna device and the rear-end power system and posing a serious threat to the flight safety of the aircraft.

[0003] Currently, lightning protection devices are usually arranged on the surface of the radome. The lightning protection devices arranged on the surface of the radome generally contain metal materials, have a certain lightning protection function, but obviously affect the working performance of the antenna device, and it is difficult to consider the lightning protection-wave penetration integration requirement. SUMMARY

[0004] The purpose of the application is to provide an aircraft radome and lightning protection-wave penetration integrated protection method for an antenna device, which solves the problem of unreasonable structure of the lightning protection device attached to the radome and the antenna device in the prior art, and the problem of difficulty in considering lightning protection-wave penetration integration protection.

[0005] The technical solution adopted by the application is an aircraft radome and lightning protection-wave penetration integrated protection method for an antenna device, and the steps are as follows:

[0006] Step 1, determining the position of lightning partition;

[0007] Step 2, determining the lightning environment;

[0008] Step 3, modeling the radome and the antenna device;

[0009] Step 4, extracting the structure parameters of the radome and the internal metal device, and determining a preliminary layout scheme;

[0010] Step 5, establishing a static electric field simulation calculation model to obtain the influence of the lightning protection device on the electric field intensity distribution inside and outside the radome before and after installation;

[0011] Step 6, establishing an electromagnetic field simulation calculation model to obtain the influence of the lightning protection device on the antenna performance before and after installation;

[0012] Step 7, lightning test is carried out;

[0013] Step 8, the static electric field simulation calculation model is optimized, and the layout of lightning protection equipment is improved;

[0014] Step 9, the influence degree of the lightning rod on the antenna performance is verified by using different test methods;

[0015] Step 10, the selection of lightning protection equipment on the surface of the radome is improved;

[0016] Step 11, the final layout scheme is determined.

[0017] The beneficial effects of the present application are that the radome and the antenna equipment can guarantee lightning protection function, and the normal working performance of the radome and the antenna equipment in the lightning process is considered, lightning protection-transmission wave integrated protection is realized, and the overall efficiency of lightning protection design of the radome and the antenna equipment is improved. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a flowchart of the method of the present application;

[0019] Figure 2 is the waveform of the voltage waveform A used in the test of the method of the present application;

[0020] Figure 3 is the waveform of the voltage waveform D used in the test of the method of the present application;

[0021] Figure 4 is the waveform of the current component A used in the test of the method of the present application;

[0022] Figure 5 is the waveform of the current component B used in the test of the method of the present application;

[0023] Figure 6 is the waveform of the current component C used in the test of the method of the present application;

[0024] Figure 7 is the waveform of the current component D used in the test of the method of the present application;

[0025] Figure 8 is a preliminary layout scheme diagram of the lightning rod protection equipment in the embodiment of the method of the present application;

[0026] Figure 9 is the electric field distribution of the surface of the radome without protection;

[0027] Figure 10 is the electric field distribution of the surface of the radome with comprehensive protection of the lightning rod and the copper mesh in the method of the present application;

[0028] Figure 11This is the calculation result of the equivalent antenna pattern using the method of the present invention when Phi=0°;

[0029] Figure 12 This is the calculation result of the equivalent antenna pattern using the method of the present invention when Phi=90°;

[0030] Figure 13 This is the calculation result of the equivalent antenna pattern after adding a guide strip when Phi=0° according to the method of this invention;

[0031] Figure 14 This is the calculation result of the equivalent antenna pattern after adding a guide strip at Phi=90° according to the method of this invention;

[0032] Figure 15 This is a schematic diagram of an antenna performance testing system based on a microwave anechoic chamber turntable used in the method of this invention;

[0033] Figure 16 The diagram shows the antenna performance indicators of the method of the present invention under three conditions: no guide strip installed on the radome, metal guide strip installed, and segmented guide strip installed.

[0034] Figure 17 This is a schematic diagram of the test setup for the effect of the guide strip on the performance of the satellite communication antenna using the method of the present invention;

[0035] Figure 18 This is a schematic diagram of the satellite communication antenna performance testing system used in the method of this invention;

[0036] Figure 19 This is a schematic diagram of the test setup for the influence of the guide strip used in the method of this invention on the performance of an antenna with a rotating mechanism;

[0037] Figure 20 This is a schematic diagram of the structure of the integrated lightning protection and wave-transmitting metal guide bar with a "wave-transmitting window" used in the method of this invention;

[0038] Figure 21 This is a schematic diagram of the integrated lightning protection and wave transmission arrangement structure of Embodiment 1 of the present invention;

[0039] Figure 22 This is a side view of the integrated lightning protection and wave transmission arrangement structure of Embodiment 2 of the present invention;

[0040] Figure 23 This is a top view of the integrated lightning protection and wave transmission arrangement structure of Embodiment 2 of the present invention;

[0041] Figure 24 This is a front view of the integrated lightning protection and wave transmission arrangement structure of Embodiment 3 of the present invention;

[0042] Figure 25 This is a side view of the integrated lightning protection and wave transmission arrangement structure of Embodiment 3 of the present invention.

[0043] In the figure, 1. Antenna RCS tester, 2. Transmitting antenna, 3. Antenna under test, 4. Computer, 5. Driver, 6. Satellite / signal tower, 7. Portable station, 8. Switch, 9. Computer 1, 10. Computer 2, 11. Spectrum analyzer, 12. Flow guide strip, 13. Internal antenna, 14. Internal other equipment, 15. Antenna cover, 16. Grounding point, 17. Copper mesh, 18. Rectangular through hole. DETAILED DESCRIPTION

[0044] The application will be described in detail below in combination with the drawings and specific embodiments.

[0045] The lightning protection-wave penetration integrated protection method of the application can realize lightning protection-wave penetration integrated protection of the antenna cover and antenna equipment of an aircraft, which are the protection objects of the application. The protection core is to increase the protection equipment with lightning arresting, current leading and flow guiding functions on the surface of the antenna cover. When the surface of the antenna cover is struck by lightning, the protection equipment can effectively arrest lightning and conduct large current along the body of the protection equipment to the mounting structure (metal part) of the antenna cover, and then safely conduct the large current to the structure ground of the aircraft by the mounting structure, so as to realize discharge of lightning current and ensure that the antenna cover and internal antenna and internal other equipment are not struck by lightning and the composite material structure of the antenna cover is not penetrated.

[0046] Lightning arresting: It usually refers to using lightning rods (meshes, wire belts) and the metal structure of a building itself to withstand direct lightning and avoid damage to the building itself. In the application, it particularly refers to the metal antenna equipment and non-metal antenna cover protruding on the surface of an aircraft. In the unprotected state, the antenna cover and antenna equipment of the aircraft often suffer direct lightning, that is, the antenna cover and antenna equipment of the aircraft often arrest lightning. In the application, the protection equipment containing metal is arranged on the surface of the non-metal antenna cover to replace the antenna cover and antenna equipment to arrest lightning, so as to realize the primary purpose of protecting the antenna cover and antenna equipment.

[0047] Current leading and flow guiding: The meanings of "current leading" and "flow guiding" are consistent. The common saying is also "current dividing". Some "current dividing strips" / "flow guiding strips" are often arranged on the surface of the antenna cover to conduct lightning protection, and the purpose is to conduct lightning large current to the designed grounding point.

[0048] Lightning protection equipment: It refers to the device / equipment containing metal components arranged on the surface of the antenna cover to arrest lightning and guide flow. The lightning protection equipment can be divided into lightning protection metal mesh (mainly copper mesh) and flow guiding strip, and the flow guiding strip is the mainstream lightning protection equipment of the antenna cover, also known as current dividing strip. (The saying of lightning protection equipment, protection equipment and flow guiding strip in the following has the same meaning and function).

[0049] Structural ground: the ground of general buildings or power systems refers to the earth / soil for the discharge of large current. The lightning protection ground is the ground for eliminating the overvoltage danger, such as the ground of lightning rod, lightning wire and lightning arrester. The lightning protection ground only has current flowing through it under the action of lightning impact, and the amplitude of lightning current flowing through the lightning protection ground electrode can reach tens to hundreds of kiloamperes, but the duration is very short. On the aircraft, there is no ground, no soil, and the ground of the aircraft can only be the network composed of the metal structure of the aircraft itself, which is generally the metal outer shell or metal frame of the aircraft, so it is also called structural ground.

[0050] Referring to Figure 1 The lightning protection and wave penetration integrated protection method of the aircraft radome and antenna device of the present application is implemented according to the following steps:

[0051] Step 1, determine the lightning partition position of the radome and antenna device;

[0052] Generally, the lightning partition is determined according to the upper-level machine;

[0053] Taking fixed-wing aircraft and helicopters as examples, whether it is a traditional metal aircraft or a newly emerging large proportion of composite material aircraft, its lightning partition is generally determined by referring to the standard documents SAE ARP 5414B-2018, GJB3567A-2023 or RTCADO-160G.

[0054] The upper-level machine of the aircraft is generally the main machine that performs lightning partition test in advance, that is, according to the test results, the different lightning attachment probabilities of each part of the aircraft are counted to divide several areas, for example, according to the partition process of SAE ARP 5414B-2018, it is generally divided into 1 area, 2 area and 3 area, wherein 1 area is divided into 1A, 1B and 1C, and 2 area is divided into 2A and 2B.

[0055] As can be seen, after the partition of the whole machine is determined by the upper-level main machine, the lightning partition of the radome and antenna device is naturally determined, and different partitions correspond to different lightning environments, that is, lightning voltage and lightning current waveform.

[0056] Step 2, according to the position of the lightning partition, determine the lightning environment faced by the protection object, that is, the input high voltage of lightning direct effect and large lightning current waveform;

[0057] Different partitions correspond to different waveforms. Before lightning test, according to the test standard selected by military aircraft or civil aircraft, the military aircraft refers to the standard GJB3567A-2023, and the civil aircraft can refer to the standard GJB3567A-2023, SAE ARP 5416A-2013 or RTCADO-160G. The relevant standards specify the corresponding test methods and waveform applications.

[0058] Take the radome of a certain type of mine lightning 1B area as an example, according to the Technical Requirements for Lightning Direct Effect Test of Radome Lightning Protection Equipment, the radome is located in the lightning 1B area, the test method is based on GJB3567A-2023 standard LT101, and the initial leader attachment test is carried out. According to the test requirements, voltage waveform D is applied, and each test is carried out twice for positive and negative polarity. As shown in Figure 2 , the voltage waveform A is a waveform with a rise rate of 1000±500kV / μs, and the amplitude increases until the test piece is broken down or the flashover slides through the test piece, and then rapidly drops to zero. As shown in Figure 3 , the voltage waveform D is a waveform with a rise time of 50µs~250µs, and the amplitude is determined by the breakdown or flashover of the test piece.

[0059] According to the lightning protection requirements of the Technical Requirements for Lightning Direct Effect Test of Radome Lightning Protection Equipment, the test piece is located in the lightning 1B area, and the arc introduction test is carried out according to GJB3567A-2023 standard LT104. The most stringent point in the initial leader attachment test is used as the arc introduction point, and at least two tests are carried out, and according to the requirements, the current components A, B, C and D are applied during the test.

[0060] The current components A, B, C and D selected for the test are all negative polarity, described as follows:

[0061] As shown in Figure 4 , the peak value of current component A is 200±20kA, the duration is less than or equal to 500µs, and the action integral reaches 2×10 6 ±0.4×10 6 A 2 s, this component is selected to be unidirectional or oscillating, and the damped oscillation waveform is selected during the test.

[0062] As shown in Figure 5 , the average amplitude of current component B is 2kA±10%, the maximum duration is 5ms, and the maximum charge transfer is 10C.

[0063] As shown in Figure 6 , the duration of current component C is between 0.25s and 1.0s, the transferred charge transfer is 200C±40C, and the current component C is unipolar.

[0064] As shown in Figure 7 , the amplitude of current component D is 100kA±10kA, the total duration is not more than 500µs, and the action integral is 0.25×10 6 A 2 s±0.05×10 6 A 2s, a double exponential wave was selected for the experiment.

[0065] Step 3: Model the radome and antenna equipment;

[0066] A three-dimensional structural model is established based on the actual dimensions of the protected object (radome and internal antenna equipment) so that electrostatic field simulation and antenna pattern simulation (antenna electromagnetic field simulation) can be performed in the three-dimensional software.

[0067] The focus of this modeling step is to establish the shape and thickness of the radome according to the actual situation, then reflect the installation spacing between the radome and the internal antenna equipment, and establish the metal structure shape (outer envelope) of the internal antenna equipment.

[0068] Step 4: Extract the structural parameters of the radome and internal metal equipment, and determine the preliminary layout scheme of the protective equipment on the surface of the radome based on the structural parameters;

[0069] Structural parameters include: First, the dimensional parameters of the metal antenna equipment, i.e., the dimensions of the antenna equipment's outer envelope. This is because the main factor affecting the probability of lightning interception is the curvature of the metal structural components, i.e., the principle of tip discharge. Tip discharge is a discharge phenomenon that occurs on the sharp part of an object under the influence of a strong electric field; it is a type of corona discharge. Due to the particularly large number of equipotential surface layers at the tip of a conductor, the electric field near the tip is particularly strong, leading to tip discharge. Second, the dimensions, thickness, and structural composition of the outer envelope of the non-metallic radome. Non-metallic radomes often employ laminated structures of composite materials, and some even have honeycomb sandwich structures, all of which need to be clearly defined.

[0070] Selecting a preliminary layout plan: This refers to the design of the layout of the protective equipment on the radome surface. The plan includes: 1) selecting the type of protective equipment, such as flow guides or lightning protection mesh; 2) selecting the model and specifications of the protective equipment, such as segmented flow guides, metal flow guides, or flow lines. For the lightning protection mesh, the areal density is determined, measured in grams per square meter (g / m²), and 73 g / m² is selected as needed. 2 142 g / m 2 195 g / m 2 Or other specifications. 3) Layout of protective equipment, such as the spacing of the guide strips, the shape in which they are arranged on the radome, and whether the guide strips and lightning protection metal mesh need to be used together, etc.

[0071] like Figure 8As shown, the protective layout scheme of the antenna cover at the top of the mast of a certain helicopter adopts a flow guide strip plan view structure, including a 1# flow guide strip, a 2# flow guide strip and a 3# flow guide strip. The 1# flow guide strip is arranged along the center line of the surface of the antenna cover and has a length exceeding the cone tip of the antenna cover. The 2# flow guide strip and the 3# flow guide strip are distributed on both sides of the 1# flow guide strip in the vertical direction and are spaced from the 1# flow guide strip, and the lengths of the 2# flow guide strip and the 3# flow guide strip do not reach the cone tip of the antenna cover.

[0072] Step 5, based on the COMSOL Multiphysics multi-physical field simulation environment, an electrostatic field simulation calculation model of the antenna cover, the antenna device and the lightning protection device is established, and the influence of the lightning protection device on the electric field intensity distribution inside and outside the antenna cover before and after installation in the lightning high-voltage environment is obtained.

[0073] The points with high electric field intensity are found out from the electric field intensity distribution of the antenna cover and the antenna device, and these points are identified as points with high lightning attachment probability.

[0074] As shown in Figure 9 , when a certain ellipsoidal antenna cover is not protected, it can be seen from the surface electric field distribution of the antenna cover 15 that the electric field intensity of the antenna cover surface near the sharp corner structure of the internal metal antenna device (not shown) is very large, that is, the part with dense electric field lines is a potential lightning attachment point. Figure 9

[0075] As shown in Figure 10 , for the surface of the antenna cover 15 shown in Figure 9 , after adding the copper mesh 17 and the flow guide strip 12 protection measures, the surface electric field intensity of the antenna cover 15 is greatly reduced as a whole, the electric field lines are most dense at the boundary of the copper mesh 17, the boundary of the flow guide strip 12 and the sharp corner, and the electric field is relatively large, while the electric field intensity near the sharp corner structure of the internal antenna is relatively reduced, and the protection effect is obviously improved.

[0076] It can be seen that the protection purpose is to transfer the points with high electric field intensity on the surface of the antenna cover to the protection device, so that the lightning can be attached by the protection device.

[0077] Step 6, according to the frequency band and attitude of the antenna device, combined with the structural parameters, material properties and layout position of the protection device, based on any simulation software environment of CST, FEKO, HFSS or EastWave, an electromagnetic field simulation calculation model of the antenna cover, the antenna device and the lightning protection device is established, and the influence of the lightning protection device on the antenna performance before and after installation is obtained.

[0078] ​The electromagnetic field simulation calculation model is mainly used for simulating the antenna performance, and needs to establish an equivalent antenna model corresponding to the antenna equipment frequency band and the radiation pattern of the protection object, simulate and calculate the antenna radiation pattern, and the main indicators are the gain, sidelobe level and 3db beam width of the antenna; after the main indicators are determined, the structure characteristics of the flow guide strip or the metal mesh consistent with the selection in the preliminary scheme are added to the model, the structure size and material properties are set, and then the simulation calculation is performed, and the important indicators (gain, sidelobe level and 3db beam width) before and after the installation of the lightning protection equipment are obtained, that is, the process of quantifying the influence of the lightning protection equipment on the antenna performance. Through comparison before and after, the layout or selection of the protection equipment is adjusted, and the protection design scheme is optimized. Because of the existence of this step, the protection method of the application can be called lightning protection-wave transmission integrated protection.

[0079] For example, in the CST-based electromagnetic field simulation calculation model environment, Figure 11 is the equivalent antenna radiation pattern calculation result when Phi=0°, the highest point of the antenna main lobe gain is 25.5dBi, the 3dB beam width is 6.5°, and the sidelobe level is -8.7dB; Figure 12 is the equivalent antenna radiation pattern calculation result when Phi=90°, the highest point of the antenna main lobe gain is 25.5dBi, the 3dB beam width is 7.2°, and the sidelobe level is -13.2dB; Figure 13 is the equivalent antenna radiation pattern calculation result when Phi=0° after adding the flow guide strip protection equipment, the highest point of the antenna main lobe gain is 24.7dBi, the 3dB beam width is 6.9°, and the sidelobe level is -9.1dB; Figure 14 is the equivalent antenna radiation pattern calculation result when Phi=90° after adding the flow guide strip, the highest point of the antenna main lobe gain is 24.7dBi, the 3dB beam width is 7.4°, and the sidelobe level is -12.6dB.

[0080] Step 7, using the lightning direct effect waveform in step 2, the lightning test is performed on the antenna cover and the antenna equipment with protection conditions,

[0081] The lightning test is divided into high-voltage adhesion damage test and large-current physical damage test, one is to determine that the antenna cover surface will not be struck by lightning from the result of the high-voltage adhesion damage test, and the lightning is attached to the protection equipment; two is to determine that the protection equipment body and the grounding of the protection equipment will not cause structural failure after bearing the large current of lightning from the result of the large-current physical damage test.

[0082] First, according to the lightning test standard, the test outline corresponding to the lightning partition of the protection object is prepared, and then the lightning test is carried out according to the test outline. The general multiple voltage test is carried out, and the test is passed if the breakdown of the antenna cover surface does not occur after multiple tests. The test data is reflected in the arc channel photo between the high-voltage electrode and the test piece in the laboratory lightning discharge moment and the visual inspection of the test piece after the test.

[0083] The purpose of the high-current physical damage test for protection design investigation is: first, the current-carrying capacity of the protection device; second, whether the grounding of the protection device is good. Generally, the protection device is grounded by the mounting fastener of the antenna cover, and finally conducted to the aircraft structure ground, so the path of the current is from the lightning channel in the atmosphere to the protection device on the outer surface of the antenna cover, and then the lightning current is conducted to the antenna cover fastener, and finally the lightning current is conducted to the aircraft metal frame (structure ground) through the antenna cover fastener, completing the discharge.

[0084] Step 8, according to steps 2, 5 and 7, by comparing the simulation calculation results and test results, the electrostatic field simulation calculation model of the antenna cover, antenna device and lightning protection device is continuously optimized, and the layout of the lightning protection device on the surface of the antenna cover is improved;

[0085] Due to the possible omissions of the protection design layout scheme in step 3 and the simulation calculation in step 5, for example, there is a difference between the actual internal antenna and the antenna cover inner surface, which leads to the breakdown of the antenna cover during high voltage test, and the lightning is attached to the surface of the internal metal antenna, and the test fails. Therefore, according to the test results, the specific way of adjustment and optimization is as follows:

[0086] 8.1) If the high-voltage attachment damage test fails, the adjustment measures for the protection device are as follows:

[0087] 1) Reduce the distance between the flow lines, make the flow line layout more dense, increase the protection range, and ensure the effective lightning attachment of the flow line; 2) Replace the flow line material with a metal material with higher electrical conductivity, such as replacing titanium alloy with stainless steel; 3) Within the acceptable degree of influence on the antenna wave transmission performance and the overall weight increase of the aircraft, increase the thickness of the antenna cover composite material to improve its insulation strength, such as increasing the thickness of glass fiber; 4) Within the acceptable degree of influence on the antenna wave transmission performance and the overall weight increase of the aircraft, replace the material of the antenna cover to improve its insulation strength.

[0088] 8.2) If the high-current physical damage test fails, the adjustment measures for the protection device are as follows:

[0089] 1) Within the acceptable range of impact on antenna transmission performance and aerodynamic performance of the aircraft surface, increase the cross-sectional area of ​​the metal portion of the guide strip to improve its ability to conduct large currents; 2) Within the acceptable range of impact on antenna transmission performance and overall weight gain of the aircraft, increase the weight of the lightning protection metal mesh to improve its ability to conduct large currents.

[0090] Step 9: Using the lightning protection equipment layout determined in Step 8, conduct antenna performance tests on the radome and antenna equipment to obtain the test results of the impact of lightning protection equipment on antenna performance. For different types of antennas and radomes, use corresponding test methods to verify the degree of influence of different models, sizes, and positions of the guide strips installed on the radome on the performance of the antenna equipment inside the radome. This can also verify the rationality of the simulation calculation results in Step 6.

[0091] Test data typically refers to comparisons of gain, sidelobe level, and 3dB beamwidth. There are several testing methods, including testing in an anechoic chamber and testing directly on the antenna surface with the antenna obscured. These are categorized as follows:

[0092] Test Method 1:

[0093] use Figure 15 The antenna performance testing system shown involves installing protective equipment onto the radome (of the protected object) to test the antenna performance. The system comprises an antenna RCS tester 1, which is electrically connected to the transmitting antenna 2, the antenna under test 3, a computer 4, and a driver 5. The driver 5 is then connected to the antenna under test 3. The preferred distance between the antenna under test 3 and the transmitting antenna 2 is 16 meters, and their top heights are both 5.5 meters.

[0094] The antenna RCS tester 1, also known as the vector network analyzer, has two ports. Port 1 is used to transmit signals of different frequency bands as a signal source; port 2 is used to receive and display signals of different frequency bands, and also has the function of signal processing.

[0095] Transmitting antenna 2, which is the antenna that transmits signals, has the same operating frequency band, polarization direction and other specifications as the antenna under test.

[0096] The functions of computer 4 are: to control the rotation of the turntable of the antenna under test 3; to process and record the signals received from different angles by the antenna RCS tester 1; and to process the signals and generate and display the measured antenna radiation pattern.

[0097] See Figure 16 The figure shows the antenna radiation curves under three conditions specified in Test Method 1: no guide bar, full-size metal guide bar, and segmented metal guide bar. This demonstrates the impact of different types of guide bars installed on the radome on antenna performance.

[0098] Specific analysis is: with the antenna cover surface without the direction diagram curve of the guide strip as the benchmark, and then comparative analysis of antenna cover surface installation metal guide strip and piece type guide strip two cases of antenna in different angle gain level gap. With 0° direction as an example, the antenna cover without installing guide strip, the antenna gain is-43dB; installation piece type guide strip, the antenna gain is still-43dB, then reflect in 0° direction, the type piece type guide strip has little effect on the antenna performance; installation full size metal guide strip, the antenna gain decreases to-46dB, then reflect in 0° direction, the type piece type guide strip has influence on the antenna performance, the specific influence degree can be according to the antenna in 0° direction gain design value to evaluate the index decline whether acceptable.

[0099] Test method two:

[0100] As shown in Figure 17 , for the size of the satellite communication antenna, the guide strip protection equipment includes two ways, namely cross shielding layout and parallel shielding layout, which can be directly covered on the antenna according to any one of Figure 17 , and the antenna performance test system shown in Figure 18 is used to test the antenna performance, which reflects the influence of different layout of the same guide strip protection equipment on the antenna performance, and the results are shown in table 1.

[0101] Referring to Figure 18 , the composition structure of the antenna performance test system is, including satellite / signal tower 6 corresponding to the measured antenna 3, portable station 7 connected with the measured antenna 3, switch 8, spectrum analyzer 11, switch 8 is connected with computer one 9 and computer two 10 at the same time.

[0102] Satellite / signal tower 6 is used to transmit signals of different frequency bands as a signal source for satellite communication antenna to receive. Portable station 7 is auxiliary equipment, which is used to indicate the direction of satellite signal and verify whether the communication function of satellite communication antenna and satellite communication link is normal. Switch 8, computer one 9 and computer two 10 are used together to program satellite communication antenna system and portable station system, which are connected with satellite communication antenna system and portable station system through network cable, and then connected to computer one 9 and computer two 10 respectively, so that personnel can operate remotely through the upper computer software installed on the computer. Spectrum analyzer 11 is used to read and display the signal level value received by the antenna.

[0103] Table 1, the influence of different layout on the antenna performance

[0104]

[0105] Test method three:

[0106] AsFigure 19 As shown, for antenna equipment with a rotating mechanism inside the radome, the protective equipment can be directly covered on the antenna and used... Figure 15 The antenna performance testing system shown tests the antenna performance and obtains the impact of the guide bar protection device on the antenna performance in the zero position state and the deflection state.

[0107] Step 10: Combining Steps 6 and 9, by comparing the simulation calculation results and test results, continuously optimize the electromagnetic field simulation calculation model of the radome, antenna equipment, and lightning protection equipment to obtain more accurate results on the impact of lightning protection equipment on antenna performance, and further improve the selection of lightning protection equipment on the radome surface.

[0108] The initial design of protective equipment generally focuses on lightning protection performance, with less consideration given to wave transmission performance. This is because protective equipment typically contains metallic materials, so lightning protection performance and wave transmission performance are usually inversely related during the design process. Through simulation calculations and experimental tests on the impact of the protective equipment on antenna performance in the initial design, an impact level can be determined. If this impact level is unacceptable, the layout of the protective equipment needs to be adjusted. Specific measures are as follows: 1) Prioritize segmented guide strips; 2) If metal guide strips must be selected due to temperature resistance, aerodynamics, etc., the width of the metal portion of the guide strip can be reduced to minimize the obstruction of electromagnetic waves to the antenna; 3) If metal guide strips must be selected due to temperature resistance, aerodynamics, etc., the continuous metal portion of the guide strip can be interrupted with openings to form a "wave-transmitting window" structure.

[0109] like Figure 20 As shown, to reduce the obstruction of antenna electromagnetic waves, the integrated lightning protection and wave-transmitting metal guide strip structure with a "wave-transmitting window" of the present invention has multiple rectangular through holes 18 spaced apart along the longitudinal center line of the guide strip 12. The spacing, length, and width of the rectangular through holes 18 need to be determined according to the antenna frequency band of the protected object. Preferably, the width of the guide strip 12 is 25 mm, the length of each rectangular through hole 18 is 20 mm, the width is 10 mm, and the interval between adjacent rectangular through holes is 30 mm.

[0110] Step 11: Based on Steps 8 and 10, determine the final layout scheme for the integrated lightning protection and wave transmission protection equipment.

[0111] The final integrated lightning protection and wave transmission protection equipment layout scheme is one that can both enable the radome and antenna equipment test pieces to pass the lightning test, and optimize the impact of the protection equipment on the antenna performance to an acceptable level or minimize the impact. This results in a balance between the lightning protection performance and the wave transmission performance.

[0112] Example 1

[0113] The invention is used for protecting a certain type of satellite communication antenna and other equipment. The integrated protection arrangement of the antenna cover is carried out according to the above steps of the method of the invention, and the final layout structure is shown in Figure 21 The outer surface of the antenna cover 15 of the satellite communication antenna is designed to be installed with ten flow guide strips 12, six of which form a closed loop circuit in sequence like a hexagonal diamond, the nodes of the hexagonal diamond are all called grounding points 16, and the other four flow guide strips 12 are arranged inside the hexagonal diamond and perpendicular to each other (in the shape of a cross, the inner ends of the four flow guide strips 12 do not contact each other), and the inside of the antenna cover 15 is provided with an internal antenna 13 and other internal equipment 14.

[0114] Through experimental verification, the overall lightning protection effect is good, the equipment runs well, and fully meets the technical requirements for product safety and operation.

[0115] Example 2

[0116] The invention is used for protecting a certain type of ellipsoidal airborne antenna. The integrated protection arrangement of the antenna cover is carried out according to the above steps of the method of the invention, and the final layout structure is shown in Figure 22 and Figure 23 A long flow guide strip 12 and two short flow guide strips 12 are designed to be installed on the surface of the antenna cover 15, the two short flow guide strips 12 are perpendicular to the long flow guide strip 12 and are connected with the long flow guide strip 12 respectively, and the two short flow guide strips 12 are arranged at both sides of the contour of the internal antenna 13 and do not block the operation of the internal antenna 13; at the same time, a lightning protection copper mesh 17 is installed on the surface of the antenna cover 15.

[0117] Through experimental verification, the overall lightning protection effect is good, the equipment runs well, and fully meets the technical requirements for product safety and operation.

[0118] Example 3

[0119] The invention is used for protecting a certain type of round head conical airborne antenna. The integrated protection arrangement of the antenna cover is carried out according to the above steps of the method of the invention, and the final layout structure is shown in Figure 24 and Figure 25 Four flow guide strips 12 are designed to be installed on the surface of the antenna cover 15 along the longitudinal direction, the four flow guide strips 12 are uniformly and spaced arranged along the circumferential direction, among them, the front ends of the two longer flow guide strips 12 exceed the contour position of the outer surface of the antenna cover 15 corresponding to the internal antenna 13, and the front ends of the two shorter flow guide strips 12 do not exceed the contour position of the outer surface of the antenna cover 15 corresponding to the internal antenna 13.

[0120] Through experimental verification, the overall lightning protection effect is good, the equipment runs well, and fully meets the technical requirements for product safety and operation.

Claims

1. An integrated lightning protection and wave transmission method for aircraft radomes and antenna equipment, characterized in that, The steps are as follows: Step 1: Determine the location of the lightning zone. The lightning zone is determined with reference to the standards SAE ARP 5414B-2018, GJB3567A-2023 or RTCA DO-160G. Step 2: Determine the lightning environment. Assuming the radome is located in lightning zone 1B, the initial leader attachment test is conducted according to the GJB3567A-2023 standard LT101. The voltage waveform D is applied according to the test requirements, and the positive and negative polarities are tested twice each. Assuming all test samples are located in lightning zone 1B, an arc introduction test is conducted according to GJB3567A-2023 standard LT104. The most stringent point in the initial leader adhesion test is used as the arc introduction point. At least two tests are conducted. According to requirements, a combination of four current components A, B, C, and D is applied during the test. The four components A, B, C, and D are explained as follows: The peak value of current component A is 200±20kA, the duration is less than or equal to 500µs, and the integral of action reaches 2×10. 6 ±0.4×10 6 A 2 The current component B is selected as either unidirectional or oscillating, and a damped oscillation waveform is used in the experiment; the average amplitude of current component B is 2kA±10%, the maximum duration is 5ms, and the maximum charge transfer is 10C; the duration of current component C is between 0.25s and 1.0s, the charge transfer is 200C±40C, and current component C is unipolar; the amplitude of current component D is 100kA±10kA, the total duration does not exceed 500μs, and the integral of action is 0.25×10. 6 A 2 s±0.05×10 6 A 2 s, a double exponential wave was selected for the experiment; Step 3: Model the radome and antenna equipment, and establish a three-dimensional structural model according to the actual dimensions of the protected object; During modeling, the shape and thickness of the radome are established according to the actual situation, the installation distance between the radome and the internal antenna equipment is reflected, and the metal structure shape of the internal antenna equipment is established. Step 4: Extract the structural parameters of the radome and internal metal equipment to determine the preliminary layout scheme. Structural parameters include: first, the dimensional parameters of the metal antenna device, i.e., the external dimensions of the antenna device; and second, the dimensions, thickness, and structural composition of the outer envelope of the non-metallic radome. Specifically, this refers to the layout design scheme of the protective equipment on the surface of the radome. The scheme includes: 1) selecting the protective equipment; 2) selecting the model and specifications of the protective equipment; and 3) laying out the protective equipment. Step 5: Establish an electrostatic field simulation calculation model to obtain the impact of lightning protection equipment installation on the electric field intensity distribution inside and outside the radome. By analyzing the electric field intensity distribution of the radome and antenna equipment, points with high electric field intensity are identified, and these points are considered to have a higher probability of lightning strike. Step 6: Establish an electromagnetic field simulation calculation model to obtain the impact of lightning protection equipment installation on antenna performance. Based on the frequency band and attitude of the antenna equipment, combined with the structural parameters, material properties and layout of the protection equipment itself, establish an electromagnetic field simulation calculation model of the radome, antenna equipment and lightning protection equipment in any simulation software environment such as CST, FEKO, HFSS or EastWave to obtain the impact of lightning protection equipment installation on antenna performance. Step 7: Conduct a lightning test. Lightning tests are divided into high-voltage attachment damage tests and high-current physical damage tests. The first test determines that the radome surface will not be affected by lightning, and that lightning strikes will only adhere to the protective equipment. The second test determines that the protective equipment itself and its grounding will not suffer structural failure after being subjected to a high lightning current. Step 8: Optimize the electrostatic field simulation calculation model and improve the layout of lightning protection equipment. The specific process is as follows: Based on steps 2, 5, and 7, the electrostatic field simulation models of the radome, antenna equipment, and lightning protection equipment are continuously optimized by comparing simulation results and test results. The layout of the lightning protection equipment on the radome surface is improved. The specific methods of adjustment and optimization are as follows: If the high voltage adhesion failure test fails, the following adjustments should be made to the protective equipment: 1) Reduce the spacing between the guide strips; 2) Replace the guide strip material with a metal material with higher electrical conductivity; 3) Increase the thickness of the radome composite material within the acceptable range of impact on antenna transmission performance and overall aircraft weight gain; 4) Replace the radome material within the acceptable range of impact on antenna transmission performance and overall aircraft weight gain. If the high-current physical destructive test fails, the following adjustments should be made to the protective equipment: 1) Increase the cross-sectional area of ​​the metal part of the guide strip within an acceptable range to ensure the impact on the antenna's wave transmission performance and the aerodynamic performance of the aircraft surface; 2) Increase the weight of the lightning protection metal mesh within an acceptable range to ensure the impact on the antenna's wave transmission performance and the overall weight increase of the aircraft. Step 9: Verify the impact of the guide strip on the performance of the antenna inside the radome using different test methods. The specific process is as follows: Using the lightning protection equipment layout from step 8, antenna performance tests were conducted on the radome and antenna equipment to obtain the test results of the impact of the lightning protection equipment on antenna performance. For different antenna and radome types, corresponding test methods were used to verify the degree of influence of different models, sizes, and placements of the flow guide strips installed on the radome on the antenna performance inside the radome, thus verifying the rationality of the simulation calculation results in step 6. The testing methods are divided into the following three categories: Test Method 1: The protective equipment is installed on the radome of the protected object, and the antenna performance is tested. Test Method Two: For large-sized satellite communication antennas, the guide bar protection equipment includes cross-blocking and parallel blocking arrangements. The protection equipment is directly covered on the antenna in either way to test the antenna performance. Test Method 3: For antenna devices with a rotating mechanism inside the radome, the protective equipment is directly covered on the antenna, and the antenna performance is tested to obtain the impact of the guide bar protective equipment on the antenna performance in the zero position and deflection states. Step 10: Improve the selection of lightning protection equipment for the radome surface. The specific process is as follows: Combining steps 6 and 9, by comparing simulation calculation results and test results, the electromagnetic field simulation calculation model of the radome, antenna equipment, and lightning protection equipment is continuously optimized to obtain more accurate results on the impact of lightning protection equipment on antenna performance, and to improve the selection of lightning protection equipment on the radome surface. Adjust the layout of the protective equipment, and take the following specific measures: 1) Select segmented flow guides; 2) If metal flow guides must be selected due to temperature resistance and aerodynamic reasons, reduce the width of the metal part of the flow guide to reduce the obstruction of the antenna's electromagnetic waves; 3) If metal flow guides must be selected due to temperature resistance and aerodynamic reasons, break the continuous metal part of the flow guide to form a wave-transparent window. The integrated lightning protection and wave transmission metal guide strip structure of the wave-transparent window is that multiple rectangular through holes (18) are spaced along the longitudinal center line of the guide strip (12). The spacing, length and width of the rectangular through holes (18) need to be determined according to the antenna frequency band of the protected object. Step 11: Determine the final layout scheme.

Images