Application of electromagnetic shielding in aerospace
Electromagnetic shielding, also known as electromagnetic compatibility (EMC), means that an electronic device neither interferes with other devices nor is affected by other devices. Its principle is mainly based on reflection loss and absorption loss. Electromagnetic compatibility, like the safety we are familiar with, is one of the most important indicators of product quality.
1:Types of electromagnetic shielding
Electromagnetic shielding is generally divided into three types: electrostatic shielding, static magneto-shielding, and high-frequency electromagnetic field shielding.
1.1:Electrostatic shielding: The conductor will reach an electrostatic equilibrium state in an electrostatic field. The internal electric field strength of a conductor in an electrostatic equilibrium state is zero everywhere. Because according to Gauss's theorem, if there is an electric field in the conductor, there will be a directional movement of charges until the electric field is zero. The conductor is made into a closed metal shell, and the area to be protected is placed in the metal shell, so that the external electrostatic field cannot affect the objects in the shell. For example, electronic devices in life often use metal shells to shield external electrostatic interference to ensure the normal operation of the internal circuit of the device.
1.2:Static magneto-shielding: Static magneto-shielding is mainly aimed at steady magnetic fields. Since the magnetic permeability of ferromagnetic materials is much higher than that of other materials such as air, when the external magnetic field passes through the shielding cover, according to Ohm's law of magnetic circuit, most of the magnetic lines of force will follow the ferromagnetic material with high magnetic permeability, and rarely pass through the shielded area, thereby achieving the effect of shielding the magnetic field. For some precision instruments, static magneto-shielding measures are used to prevent external magnetic fields such as the geomagnetic field from interfering with their measurement results.
1.3:Electromagnetic shielding: For alternating electromagnetic fields, when the alternating electromagnetic field is incident on a metal shield, an induced current will be generated on the metal surface according to the law of electromagnetic induction. This induced current will generate a secondary electromagnetic field in the opposite direction of the original electromagnetic field according to the Ampere loop theorem. According to the superposition principle, the two electromagnetic fields superimpose and cancel each other out, thereby weakening the electromagnetic field strength entering the shield. Its shielding effectiveness mainly depends on factors such as the conductivity, magnetic permeability and thickness of the shielding material. For example, in the field of communications, in order to prevent signal interference, the communication line will be electromagnetically shielded to ensure stable signal transmission.
2:Applications in the aerospace field
2.1:Communication systems:
In aerospace vehicles, communication equipment is crucial and usually requires electromagnetic shielding protection. Very high frequency communication systems (VHF), high frequency communication systems (HF) and satellite communication systems (SATCOM), etc., receive and transmit weak radio frequency signals. In a complex electromagnetic environment such as an aircraft, if there is no electromagnetic shielding protection, it is easy to be electromagnetically interfered by other electronic equipment. For example, the engine, motor and other equipment on the aircraft will generate electromagnetic radiation when working, which will interfere with the signal reception and transmission of the communication equipment, resulting in a decrease in communication quality or even communication interruption.
Not only the electronic equipment on the aircraft, but also the aircraft may be interfered by strong electromagnetic pulses generated by lightning when flying in the earth's atmosphere. The electromagnetic shielding layer can block these interferences and ensure that the signals received and sent by the communication equipment are clear and stable.
Moreover, the communication equipment itself may also generate electromagnetic radiation, affecting the operation of other sensitive electronic equipment, so electromagnetic shielding can play a two-way protective role.
Its shielding material is usually metal foil or metal mesh, which reflects and absorbs electromagnetic interference so that the signals within the communication frequency range can be transmitted normally.
For aerospace vehicles, when passing through the earth's ionosphere and performing missions in space, they will encounter cosmic electromagnetic radiation such as solar storms. Electromagnetic shielding can effectively protect communication equipment, such as the communication link between deep space probes and Earth control centers. Shielding measures ensure the accurate transmission of telemetry and remote control signals, avoid signal loss or errors, and ensure the smooth progress of space missions
2.2:Navigation system:
The navigation system of an aircraft includes an inertial navigation system (INS), a global positioning system (GPS) receiver, etc. Electromagnetic shielding can prevent the influence of radio frequency interference (RFI) on navigation equipment.
Taking GPS as an example, the satellite signal it receives is very weak and easily interfered with. Without electromagnetic shielding, the electromagnetic noise generated by other electronic equipment inside the aircraft may drown out the GPS signal, making the positioning accuracy reduced or impossible to locate.
Near the airport, the aircraft's navigation system may be interfered by electromagnetic signals emitted by ground communication base stations, radars and other equipment. Electromagnetic shielding shells can reduce these interferences, allowing navigation equipment to accurately receive satellite signals and accurately calculate the position, speed and attitude of the aircraft.
2.3:Control system:
Computers, sensors, actuators and other components in the flight control system all require electromagnetic shielding. Take the aircraft's fly-by-wire control system as an example, which transmits control commands through wires. Electromagnetic shielding can prevent the transmission of erroneous commands caused by electromagnetic interference. During the flight of an aircraft, electromagnetic radiation generated by equipment such as the engine and external electromagnetic interference may affect the normal operation of the flight control system. By adopting electromagnetic shielding technology, such as wrapping a metal shielding layer around the control line, these interferences can be effectively blocked to ensure that the flight control system can accurately control the aircraft's various control surfaces and engine power according to the pilot's operation or the instructions of the autopilot system. In the aerospace field, the flight control system is more complex for reusable spacecraft. During the launch and re-entry stages, electromagnetic shielding can ensure that the flight control system operates stably in harsh electromagnetic environments and avoid serious accidents such as loss of control of flight attitude caused by electromagnetic interference.
2.4:Monitoring system:
Traffic collision avoidance system (TCAS) and weather radar (WXR) also need electromagnetic shielding. TCAS needs to accurately receive and process the transponder signals of surrounding aircraft to determine the risk of collision. Electromagnetic interference may cause it to misjudge the position, altitude and other information of surrounding aircraft, thereby issuing erroneous collision avoidance instructions. The microwave signals transmitted and received by weather radar are used to detect weather conditions. Electromagnetic interference may cause errors in radar images, such as misjudging interference signals as weather targets, or failing to accurately display the actual location and strength of weather targets, affecting the pilot's judgment of weather conditions.
In the aerospace field, most of the above systems require electromagnetic shielding protection to ensure their normal operation and improve the safety and reliability of flight. At the same time, electromagnetic shielding also helps to reduce mutual interference between devices, so that the aircraft electronic system can operate in a coordinated and stable manner.
Our company provides high-quality electromagnetic shielding materials, which can be customized. For more detailed information, please visit the website: https://www.ec3dao.com/
Thank you for your browsing. If you have any questions, feel free to contact us!