Measurements using Optic and RF Waves

Chapter 10Measurement for the Evaluationof Electromagnetic Compatibility¹

 

 

 

10.1. Introduction

The measurement of electromagnetic compatibility (EMC) is a very specific field of electromagnetic measurement. In general, it has two objectives corresponding to the two complementary aspects of electromagnetic compatibility. Firstly, EMC measurement aims to measure the characteristics of electric and electromagnetic signals unintentionally produced by a test device — this is emissivity or emission measurement. In this case, the emissivity level must be limited. Secondly, EMC measurement aims to use this same test device to simulate an electric or electromagnetic disturbance device — this is immunity or sensitivity measurement. In this case, the level of immunity must again lie above the minimum acceptable threshold.

To recreate the coupling phenomena likely to occur during the life of a product requires an extensive combination of resources, environments and test conditions. The first difficulty is therefore to define the precise conditions in which the tests should be conducted in order to cover a very wide range of different scenarios identified by experts. This is obviously a vast subject. As an example, an EMC test can reproduce situations as diverse as an analysis of sensitivity to waveforms representing lightning strikes, electrostatic discharge, specific signals relating to power cable interference, etc.

For brevity, we will concentrate our analysis on two large families ...