Evaluating EMC Measurement Needs

July 17, 2015
Having so many wireless devices in a crowded location requires that these electronic products meet strict requirements for levels of electromagnetic interference (EMI) and electromagnetic compatibility (EMC), lest the transmission from one device block the reception of another device nearby.

Wireless electronic products continue to spread into many different areas, ranging from the most secretive military and aerospace applications to the most popular consumer and commercial markets (smartphones, to give one notable example). In fact, it is safe to say that wireless electronic devices have become essential social networking tools for many users, and many folks would be literally lost without having the Global Positioning System (GPS) satellite receiver built into their smartphones to guide them.

Of course, having so many wireless devices in a crowded location requires that these electronic products meet strict requirements for levels of electromagnetic interference (EMI) and electromagnetic compatibility (EMC), lest the transmission from one device block the reception of another device nearby. For this reason, EMC testing of different wireless electronic products can be considered a truly underrated part of the electronic product manufacturing process, and one of the series of high-frequency measurements that depends strongly on the reliability of commercial test equipment.

Of course, in some cases, such as medical devices and equipment, lives may depend on the electronic products meeting EMC requirements. As RF/microwave electronic circuits are playing stronger roles in such market areas as automobiles, medical and health equipment, and surveillance and safety equipment—and being used in these products with increasing density—EMC measurements become vital to the success of a product.

EMC measurements traditionally have been performed with the aid of a spectrum analyzer or a dedicated EMC field-strength analyzer and, in the past, these measurements were made with larger, bench top instruments. But those tasked with EMC measurements now have a greater choice of test instruments for this purpose than ever before, with a growing number of portable spectrum analyzers outfitted with near-field probes for making on-site EMC measurements.

Rather than checking for EMC in a test laboratory, these measurements can now be made in the field and under actually operating conditions. This allows for a better understanding of an electronic product’s performance within the environments where it is most likely to be used.

Properly performing EMC measurements requires the right test equipment (such as spectrum analyzers typically covering the frequency range from 9 kHz to 1 GHz) and the right accessories (such as near-field probes and a reliable tracking generator as a source of test signals). But it also requires the knowledge and experience in performing these measurements, since these measurements must be conducted under different sets of conditions and with specific test-equipment controls and adjustments. Professional organizations such as the IEEE can be a huge help to engineers wanting to learn more about performing EMC measurements.

In addition, organizations devoted to education, such as  LearnEMC, offer one- and two-day short courses on EMC measurements, and will even come to a client company to present the course. As an example, the firm’s course, “The Physics of Electromagnetic Compatibility Measurements,” reviews the unintentional generation, propagation, and reception of electromagnetic (EM) energy, as well as the required test equipment and test settings and how different setup parameters can affect measurement results. The course covers automotive, commercial, and military test procedures; it reviews the measurements in generic ways, rather than as approaches specific to any one market or industry.

EMC measurements certainly are important and worth the time to learn, especially for companies with electronic products where EMC performance can make a life-or-death difference (e.g., the aforementioned  medical devices). As wireless technology continues to spread, these measurements and the test instruments needed to perform them grow in importance, and will be detailed more closely in future installments of this blog.

About the Author

Jack Browne Blog

Jack Browne, Technical Contributor, has worked in technical publishing for over 30 years. He managed the content and production of three technical journals while at the American Institute of Physics, including Medical Physics and the Journal of Vacuum Science & Technology. He has been a Publisher and Editor for Penton Media, started the firm’s Wireless Symposium & Exhibition trade show in 1993, and currently serves as Technical Contributor for that company's Microwaves & RF magazine. Browne, who holds a BS in Mathematics from City College of New York and BA degrees in English and Philosophy from Fordham University, is a member of the IEEE.

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