Strategies Using Time-Domain Measurements for Radiated Emissions Testing in Harsh Environments

Abstract

Performing in-situ radiated emissions measurements, that is, in locations different from a standard test site, can be a challenging task because of the high electromagnetic noise levels in the ambient. A harsh electromagnetic environment characterizes such sites, and it usually results in difficulties when discerning between emissions from the equipment under test (EUT) and electromagnetic fields generated by surrounding devices. Moreover, communication signals from broadcasting services are generally significantly higher than the standard emission limits, making it even harder to determine compliance. In this article, we present different techniques leveraging the advantages of time-domain measurement systems to provide effective and practical solutions to mitigate ambient noise’s effect on radiated electromagnetic interference measurements. First, the test method used is described, and pragmatic considerations are given to ensure reliable and repeatable measurements. Multichannel time-domain measurement systems are introduced as the fundamental tool for the proposed strategies. Subsequently, different study cases are evaluated with real test examples, highlighting several criteria intended to reduce the impact of ambient noise on the actual emissions measures produced by the EUT. Finally, a real application of those strategies for measuring a photovoltaic system is described. Overall, the methods employed and the main advantages of using full-time-domain FFT-based receivers are reviewed. In addition, the possibility of incorporating this article’s outcomes into forthcoming electromagnetic standards about in-situ radiated emission measurements is also debated.