Browse Definitions:

EM shielding (electromagnetic shielding)

Contributor(s): Matthew Haughn

EM shielding (electromagnetic shielding) is the practice of surrounding electronics and cables with conductive or magnetic materials to guard against incoming or outgoing emissions of electromagnetic frequencies (EMF).  

EM shielding is conducted for several reasons. The most common purpose is to prevent electromagnetic interference (EMI) from affecting sensitive electronics. Metallic mesh shields are often used to protect one component from affecting another inside a particular device. In a smartphone, for example, a metallic shield protects electronics from its cellular transmitter/receiver. Radiation shields in mobile phones also decrease the amount of radio frequency (RF) energy that might be absorbed by the user. 

To increase the security of air gapped systems, EM shielding is advised. Conventionally, physical isolation and a lack of external connectivity have been considered adequate to ensure their security. However, proof-of-concept attacks have demonstrated that acoustical infection can be enabled by exploiting the electromagnetic emanations of the system’s sound card.

Air-gapping is used in the military, government and financial systems like stock exchanges. The measures are also used by reporters, activists and human rights organizations working with sensitive information. 

A number of different materials and techniques are used for EM shielding. Wires may be surrounded by a metallic foil or braid shield to block errant EMI from the cased wires. Audio speakers often have inner metallic casing to block EMI produced by the drivers so they don’t affect TVs and other electronics. Complete continuous enclosure is not necessary so long as any openings are smaller than the electromagnetic waves that need to be blocked.

Special conductive paints can be used to prevent the EMF from networks escaping the originating business to prevent eavesdropping or wireless attacks. These techniques are like a miniature Faraday cage, which can prevent signal corruption that would cause electronics to perform unexpectedly. 

Electronics may also have connections filtered for EMI by use of electronic components like capacitors, ferrules and grounded wires to minimize the effects of EMI noise -- even twisting wires together with grounds can reduce lower interference.

Magnetic materials must be used for EM shielding in environments where the magnetic fields are slowly varied below the 100Khz range as a Faraday cage-type solution is ineffective in that situation. With magnetic materials, the EMI is drawn into the magnetic field of the shielding.

This was last updated in August 2014

Continue Reading About EM shielding (electromagnetic shielding)

Join the conversation

1 comment

Send me notifications when other members comment.

By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy

Please create a username to comment.

It was so awesomely helpful and helped me a lot to discover. It enriched my knowledge about EM Shielding.


File Extensions and File Formats


  • risk map (risk heat map)

    A risk map, also known as a risk heat map, is a data visualization tool for communicating specific risks an organization faces. A...

  • internal audit (IA)

    An internal audit (IA) is an organizational initiative to monitor and analyze its own business operations in order to determine ...

  • pure risk (absolute risk)

    Pure risk, also called absolute risk, is a category of threat that is beyond human control and has only one possible outcome if ...


  • federated identity management (FIM)

    Federated identity management (FIM) is an arrangement that can be made among multiple enterprises to let subscribers use the same...

  • cross-site scripting (XSS)

    Cross-site scripting (XSS) is a type of injection security attack in which an attacker injects data, such as a malicious script, ...

  • firewall

    In computing, a firewall is software or firmware that enforces a set of rules about what data packets will be allowed to enter or...



  • business continuity and disaster recovery (BCDR)

    Business continuity and disaster recovery (BCDR) are closely related practices that describe an organization's preparation for ...

  • business continuity plan (BCP)

    A business continuity plan (BCP) is a document that consists of the critical information an organization needs to continue ...

  • call tree

    A call tree -- sometimes referred to as a phone tree -- is a telecommunications chain for notifying specific individuals of an ...


  • all-flash array (AFA)

    An all-flash array (AFA), also known as a solid-state storage disk system, is an external storage array that uses only flash ...

  • volume manager

    A volume manager is software within an operating system (OS) that controls capacity allocation for storage arrays.

  • external storage device

    An external storage device, also referred to as auxiliary storage and secondary storage, is a device that contains all the ...


  • hybrid hard disk drive (HDD)

    A hybrid hard disk drive is an electromechanical spinning hard disk that contains some amount of NAND Flash memory.