Comprehensive Analysis of Pulsed-CW Excitation in Reverberation Chambers

Abstract

Radiated Susceptibility tests in reverberation chambers are commonly performed under continuous-wave excitation. This article focuses on pulsed-CW excitation where a monochromatic CW signal is modulated by a rectangular pulse. This kind of excitation presents the advantages to expose the equipment under test to more realistic signals and broadening the effective excitation bandwidth around the carrier frequency. This study first aims to understand the physical phenomena involved in this narrowband excitation in a reverberant enclosure. The average envelope of the signal induced on the receiver (i.e., a receiving antenna) being decomposed in three different regions called “rise-time,” “steady-state,” and “fall time.” It is then shown that the a priori knowledge of the quality factor of the enclosure enables an accurate prediction of the average envelope of the received individual pulses in sufficiently well-stirred conditions. Finally, it is shown that a time-varying environment (i.e., a continuous stirring process) as the one obtained in a classical parallelepipedal RC continuously stirred or in a vibrating intrinsic RC (i.e., VIRC) allows a clear reduction of the overshoots observed on individual pulses during both transitions regions. Under these conditions, a high fidelity to the excitation signal can be achieved at the receiver, especially when the RC is loaded with absorbing material. The final objective of this article is therefore to contribute to demonstrate to the community of RC users that a pulsed-CW excitation in an RC can be well controlled and predictable, and thus capable of producing reproducible tests.