EMC FLEX BLOG A site dedicated to Automotive EMC Testing for Electronic Modules

Shielding Effectiveness

27. April 2016 01:39 by Christian in EMC/EMI
The generic shielding effectiveness requirement is 40 dB for magnetic field, electric field, and pla

The generic shielding effectiveness requirement is 40 dB for magnetic field, electric field, and plane waves. Depending on the application the frequency range can start from 10 Hz going up to GHz.

To predict shielding effectiveness (SE) of a metal sheet the following factors are summed:  Absorption Loss (A), Reflection Loss (R), re-Reflection Correction Factor (C).  SE = A + R – C (see MIL-HDBK-419A).

 

 

 

 

 

 

 

 

 

 

 

Absorption loss depends on material thickness, permeability, electrical conductivity, and the frequency of the incident wave.  It is the same for all electromagnetic waves.

Reflection loss depends on the distance of the EMI source to the material (different for electric, magnetic, and plane waves), material electrical conductivity, and the frequency of the incident wave.

Sources:
Christian Rosu
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