Electromagnetic Reverberation Chambers

Chapter 6

Emissivity Tests in Reverberation Chambers

6.1. Introduction

Chapter 5 was devoted to measurements of radiated immunity, which are certainly at the origin of the current upsurge the use of reverberation chambers in several industrial sectors. However, the first research studies on this subject[COR 76] had as an objective the measurement of microwave radiations. Indeed, the stochastic nature of the field was first postulated during these initial studies. This stochastic behavior is potentially produced by an electromagnetic cavity of large dimension compared to the wavelength, in mode stirring operation. We then quickly noticed that the reverberation chamber behaved in such a way that the intrinsic directivity of the radiating element placed inside was mostly hidden. The standing wave regime present in the cavity strongly contributes to hide this directivity and the stirring operation strengthens this property. Therefore, an antenna also set in the enclosure enables us to intercept an electromagnetic signal, whose amplitude is directly linked to the radiated power supplied by the transmitter.

This property is at the origin of the use of reverberation chambers for the determination of the total radiated power of a device under test. The total radiated power can notably enable us to characterize the unintentional radiation of a device,in order to evaluate its interference level. In this chapter we will take a more particular look at the applicable methods of quantifying ...