What is Electromagnetic Interference (EMI)?

Electromagnetic interference (EMI) refers to the disturbance caused by electromagnetic signals generated during the operation of electronic devices or systems. These disturbances can generate noise, result in signal degradation, or complete malfunction, leading to operational issues and potentially compromising the functionality of affected electronic equipment. 

What causes of EMI?

There are various sources of electromagnetic interference (EMI) both natural and man-made. Man-made sources of EMI can be any electronic system through which electric current flows. Whenever electric current flows through a circuit a small magnetic field is generated. A changing magnetic field generates an electric field and vice-versa – the two are linked. These changing fields form electromagnetic waves. During their operation, all electronic devices emit EM waves that can propagate through the surrounding environment and disrupt the operation of nearby electronic devices. The fluctuations in electrical power supply can also introduce EMI into sensitive electronic systems. 

Natural electromagnetic interference is caused by natural sources and events like solar flares, lightning, and auroras. It can sometime happen without warning, causing interference to electronic devices that are not appropriately protected. 

Image showing various sources of EMI [Credits: NHAIT]  

Effects of Electromagnetic Interference 

EMI has diverse effects on the performance of electronic devices and systems. It may result in signal degradation causing distortion or loss of transmitted information. In some cases, it may disrupt normal operations to a point where extreme malfunction or complete failure occurs. Furthermore, EMI can introduce noise into circuits thereby reducing signal quality and increasing the probability of errors. 

Cross-talk between adjacent circuits or channels is another consequence that leads to signal interference and data corruption. In safety-critical environments, EMI endangers lives by compromising the functionality of vital systems like medical devices or aircraft navigation systems.  

EMI Mitigation Techniques 

Shielding of components on a Printed Circuit Board 

There are a lot of techniques to mitigate the disruptive effects of electromagnetic radiation on electronic devices and systems. This includes shielding sensitive components with metallic enclosures and ensuring proper grounding to protect the electronics inside. Twisted pair cables are also used to cancel out the effects of interference. Additionally, adherence to regulatory standards for electromagnetic compatibility further helps in mitigating the effects of EMI. By implementing these strategies, EMI can be reduced by a significant amount.