Reasons and Measures for Electromagnetic Leakage in Shielding Room Gaps

The shielding effectiveness of a shielding body can be represented by shielding coefficient or shielding attenuation. In the space protection zone, the ratio of the field strength (E0 or H0) in the presence of a shield to the field strength (E or H) in the absence of a shield, i.e. E0/H0 or H0/H, is called the shielding coefficient. The smaller the shielding coefficient, the better the shielding effect. The shielding effect can also be represented by shielding attenuation, which represents the attenuation value of interference field strength through the shielding body. The shielding attenuation can be obtained by or - unit decibels (dB). The larger the shielding attenuation value, the better the shielding effect.
Reasons for electromagnetic leakage in the gaps of the shielding room:
Impedance at the gap: The impedance of the gap can be equivalent to that of a resistor and a capacitor in parallel, because the point on contact is equivalent to a resistor, and the point without contact is equivalent to a capacitor. The entire gap is a parallel connection of many resistors and capacitors. At low frequencies, the resistance component plays a major role; At high frequencies, the capacitive component plays a major role. Due to the decrease of capacitance impedance with increasing frequency, if the gap is the main leakage source, the shielding effectiveness advantage of the shielding case increases with increasing frequency. However, if the size of the gap is large, high-frequency leakage is also the main phenomenon of gap leakage.
Measures to solve gap leakage:
1. The overlapping area of the contact surface can reduce resistance and increase capacitance.
2. Use as many fastening screws as possible, which can also reduce resistance and increase capacitance.
3. Adhere to clean contact surfaces and reduce contact resistance.
4. Adhere to good flatness of the contact surface, which can reduce resistance and increase capacitance.
5. Use electromagnetic sealing to seal the gaps, eliminate the cause of electromagnetic leakage on the gaps and eliminate non contact points.