Strategies For Pre-compliance EMI Testing Of Radiated Emissions
by Dylan Stinson, Tektronix, Portland, Oreg., How2Power Today, Jul 16 2018
Focus:
You can often avoid multiple unwanted trips to the test house and ill-timed product delays by
measuring the radiated emissions produced by your product prior to going to the test house.
This type of pre-compliance testing will increase your chances of passing EMC compliance
testing the first time out and reduce the need for last-minute product redesigns. This article
discusses the types of equipment required for performing precompliance radiated EMI testing,
and offers guidelines for making the test setups and measurements. This includes the choice of
suitable test locations and placement of equipment. The three detection methods associated with
EMI testing—quasi-peak, peak and average detection—are explained. Then the article discusses
the benefits of real-time spectrum analyzers, near-field probes and mixed-domain oscilloscopes
in identifying and troubleshooting noise sources. Finally, some tips for making repeatable
measurements are given.
What you’ll learn:
- How to perform precompliance EMI testing of radiated emissions of power supplies and other hardware designs
- How to understand the differences between quasi-peak, peak and average detection in EMI measurements
- How to understand the benefits of real-time spectrum analyzers, near-field probes and mixed-domain oscilloscopes in identifying and troubleshooting EMI noise sources
Notes:
Written from the perspective of a test instrument company, this article is complementary to Tim
Hegarty’s “The Engineer’s Guide To EMI In DC-DC Converters (Part 4): Radiated Emissions”.
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