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With the increased sensitivity of electronic systems, shielding has become crucial to allow acceptable military standards of EMI/EMC.

Because environmental electromagnetic conditions are unpredictable by nature, having effective shielding in place removes this particular threat to military electronics. 

EMI stands for electromagnetic interference while EMC is the acronym for electromagnetic compatibility. Electromagnetic interference refers to the effect that these fields can have on other devices nearby. Motors, transformers and other devices which use a lot of power tend to produce significant magnetic fields. A small amount of EMI can easily interrupt input and output data signals, so having the right protection in place is crucial to the smooth running of equipment. 

The goal of shielding is to completely prevent any sensitive electronic equipment from being impacted by EMI or radio frequency interference. While EMI shielding is typically associated with highly complex equipment used in specialist fields, a form of it is also used in everyday electronics such as smartphones.

Typically, a metallic screen is placed all around the equipment and used to absorb the signals, meaning that anything incoming and outgoing is prevented from having an effect. In many cases, the sensitive equipment is also transmitting EMI of its own, so the shielding works both ways.

The material used to create EMI shielding depends upon the specific equipment in question. Metallic foil or plated metallic braid, for example, can be used for shielding wires. This must be attached to the metal casing, and connectors at the ends of the wire must have metal covers, to ensure complete protection. 

Inner metallic casing, on the other hand, can protect devices like audio speakers from incoming EMI from nearby devices.

Other commonly used shielding materials to meet military EMI/EMC standards include:

  • Sheet metal
  • Metal foam
  • Conductive paints and conductive plastics where the magnetic field is below 100kHz

Want to learn more? Tonex offers Military EMI/EMC Training, a 3-day comprehensive course that covers the theory of EMC/EMI and all aspects of MIL-STD-461 and MIl-STD-464. Training also covers the basic math and the physics of EMI/EMC and the fundamentals of instrumentation, instruments, test setups and real measurements.

For more information, questions, comments, contact us.

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