The existence of a shielding room serves to isolate external electromagnetic interference and ensure the normal operation of indoor electronic and electrical equipment. The working principle is that the shielding system conducts interference and eavesdropping experiments to ensure the security and reliability of the website. What are the reasons for the radiation reduction mentioned by the shielding room company?
Cables still account for a large proportion of the entire system, and the following situations usually occur in electromagnetic compatibility tests:
No matter how the equipment is improved, it cannot pass the electromagnetic compatibility test, but when the external cable of the equipment is removed, the equipment can pass the test smoothly; In practical use of electronic devices, it is also common to encounter situations where the device cannot function properly or even crashes frequently, but after unplugging the connecting cable, everything returns to normal. Actually, the above questions The ultimate cause is attributed to electromagnetic compatibility issues, mostly caused by cables.
Radiation Model of Shielded Room Connecting Cables
The differential current loop is the signal current loop in the cable, while the common mode current loop is formed by the cable and the ground. The cable contains both signal lines and signal ground lines, with a small distance between them, resulting in a very small area of differential mode current loop. Therefore, its differential mode radiation is not strong. In addition, due to the opposite direction of current in adjacent joints, the direction of the magnetic field generated is also opposite, which cancels out in space. Therefore, the actual radiation generated mainly comes from common mode radiation.
Incorrect connection was made between the cable and the cabinet during use, and the shielding effectiveness of the cabinet returned to normal after unplugging the connecting cable. This indicates that cables are the direct cause of the reduced shielding effectiveness of the system. The radiation problem that occurs after the cabinet is connected to the cable described by the shielding room manufacturer is hoped to be helpful to practitioners!
