Electromagnetic Interference (EMI)

EMI or Electromagnetic interference is a term which is commonly used  to describe interference in electric circuits by an external source.

There are many different sources for Electromagnetic Interference.  EMI is generally classified based on its source into two broad categories.

  • Man-Made EMI which originates from other man made sources such as power lines, electric appliances and circuits.  The switching of electric circuits can cause interference.  Microwave ovens can also cause EMI
  • Naturally occurring EMI which refers to interference from natural sources such as Lightning Discharges, Solar phenomena, etc.

EMI causes disturbance to electronic systems such as radio and television and wireless communication systems.  Analog communication systems based on amplitude modulation (AM) are particularly susceptible to EMI interference as they have low selectivity.

Protecting Devices against EMI

  1. Electric and Electronic Devices are usually protected against EMI by enclosing them in a metallic enclosure. 
  2. If possible, move known sources of EMI such as microwave ovens, cell phones away from sensitive electronic circuits.
  3. Ensure that the device is properly grounded. 
  4. To protect a large area such as a room from Electromagnetic Interference, a Faraday cage may be constructed.  A Faraday Cage is an enclosure made of conductive material or a mesh.