Electromagnetic Shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials.
Applicable definitions and concepts:
- Shielding effectiveness = A measure of the reduction or attenuation in electromagnetic field strength caused by the use of a shield between the source and that point.
- Decibel (dB) – The unit of measure used to determine shielding effectiveness: SE(shielding effectiveness) = 20 log10 (E1 / E2) dB
In terms of functionality, shielding radiated emissions at the presence of a seam or opening of the electronic product or system by reflecting, absorbing or redirecting electric/magnetic fields.
Nearly all high-speed, electronic devices require electromagnetic shielding in order to operate. Some examples are: computers, industrial controls, medical devices, telecommunication equipment, military and commercial electronic systems. These and many other electronic devices and systems utilize electromagnetic shielding in the forms of air vent panels (Figure 1), conductive viewing windows (Figure 2), board level shields (Figure 3) and gaskets made of conductive elastomer (Figure 4), wire mesh (Figure 5) and Fabric over Foam gaskets (Figure 6).
The shielding material to be used is largely determined, not only by the shielding needed per the operating frequency, but by the electronic product or systems intended use in an environment such as office, factory/warehouse, outside, and/or near salt water. Other affiliated physical environmental conditions that determine the best shielding material is galvanic compatibility of the shield material mating conductive surface, vibration, and temperature.
Figure #1 Shielded Ventilation Panels
Shielded Ventilation Panels provide optimum electromagnetic/radio frequency interference (EMI/RFI) shielding with minimum pressure drop for the ventilating air. Shielding effectiveness is accomplished using waveguide design principles. Learn More >>
Figure #2 EMI Shielded Windows
MAJR Products provides EMI Shielded Windows solutions to many industries based on requirements for electromagnetic shielding, high light transmission, coatings for hardness, anti-glare, and other optical considerations. Learn More >>
Figure #3 Board Level Shields
MAJR Products offers Board Level Shields that isolate components and minimize cross-talk while maximizing performance on your PCB. Our shields provide isolation of board-level components and come in custom shapes that can incorporate a removable lid for ease of access to your components. Learn More >>
Figure #4 Conductive Elastomer Gaskets
MAJR Products’ Conductive Elastomer is a molded elastomer filled with conductive inert particles. It provides high electrical conductivity, broadband shielding and moisture sealing.Learn More >>
Figure #5 Wire Mesh Gaskets
All Mesh EMI-RFI knitted wire gasketing is available in various cross sections to satisfy the many different requirements encountered in shielding applications. The choice between rectangular, round, round with fin or double round with fin depends on the enclosure or equipment to be shielded. Learn More >>
Figure #6 Fabric over Foam Gaskets
Fabric Over Foam Gaskets are available in a variety of profiles, including Asymmetrical, C-Fold, P, and D shapes. Customized profiles and fabricated die-cut parts including I/O shielding for Mil and D-Sub connectors can be manufactured to meet specific requirements with no (or minimal) set-up cost. Learn More >>
Contact MAJR Products Corporation for guidance on electromagnetic shielding and the correct shielding materials to use for your specific application.