EMI stands for Electromagnetic Interference. It is a generalization of an older terminology RFI (Radio Frequency Interference). EMI can be defined as an electromagnetic or electro static disturbance that causes malfunctioning or undesired response in one or more electronic system, equipment or circuit. In this post, we will focus on the different types of EMI.

An EMI can be classified into various categories. Few of them are:

Intentional EMI:

It is also Known as functional EMI. As its name suggests, It is the EMI which we generate intentionally. In this, the equipment are designed to emit electromagnetic energy. For ex – Radars and Radio transmitter, jammers etc.
We use it in Electronic warfare extensively.

GPS Jammers

Unintentional EMI :

It is also Known as non functional since these are not designed to emit electromagnetic energy and where as such an emission is purely incidental. These sources includes Man made sources which are not intended/designed to generate EM energy but still they radiate in actual. These sources may be DC motors, Electrical controllers, Engines igniters, Computers, Fluorescent lighting, Power lines, Welding machines and many more.

Types of EMI - IncidentalIntra System EMI :

Intrasystem EMI occurs as a result of self-jamming or undesirable emission coupling within a system. Such interference can develop as a result of voltage or current spikes that appears on power cables and wiring harnesses. These spikes can be electrically or magnetically coupled in adjoining sensitive cables via cable to cable capacitance and or inductance, thereby causing undesirable signal to appear.

An example of System EMI

Intersystem EMI :

Intersystem EMI occurs between discrete system operating within a wide frequency range from lower to micro wave frequencies (50 Hz to several Ghz).

  Various EMI sources in Day to day life

The different types of EMI can also be classified in terms of their bandwidth. They are:

  • Broadband EMI:

    A broadband EMI can occur through a source like arc welding in which continuous generation of arc is involved. Natural broadband EMI can also be observed because of the Sun.

  • Narrowband EMI:

    The unwanted signals generated due to a distortion or inter-modulation are example of Narrowband EMI. These unwanted signal can be located anywhere in the spectrum.