EMC Design Guide for Printed Circuit Boards- Automotive EMI-EMC

1. Introduction

Due to the tremendous increase in the use of electronic devices, ensuring Electromagnetic Compatibility (EMC) of a full system in its early design phase is becoming one of the major technical issues. Safe and reliable operation must be guaranteed and legal requirements have to be satisfied. From both car-makers and suppliers sides, the electromagnetic problems occur either when integrating electronic devices in their operating environment (cross-coupling, interference) or when dealing with the related EMC regulations (simulation of radiating phenomena due to  Common-Mode currents induced on attached cables). As digital devices become smaller and perform at greater speeds, their emissions increase, making a thorough understanding of Electromagnetic Interference (EMI) essential for everyone in electrical engineering and design today

2. Types of Electromagnetic radiation

Electromagnetic radiation due to the operation of electrical or electronic devices may be grouped into two types:
• Intentional Emissions
• Unintentional Emissions
Examples of the first type are television and radio broadcasting systems, communication and radar systems, and transmitters for navigational purposes. However, even when performing  properly such equipment may also generate undesired electromagnetic emissions of the second type. This might interfere with the system itself or the overall emissions might affect other sensitive equipment nearby. In order to control these kind of effects frequency management is necessary in the first place due to the fact that a certain part of the emission profile contains valuable information and is intended to be there.