Overview:
Failures during EMC product qualification testing can result in expensive delays and possible redesign. Understanding simple EMC design basics go a long way towards minimizing these risks. This webinar will review the most common design issues and demonstrate simple troubleshooting techniques to identify issues early in the design process.
What You Will Learn:
– Basics of differential- versus common-mode currents
– Common issues leading to radiated emissions
– Tools used to identify and confirm emission sources
– Troubleshooting radiated emissions
Click here to download a copy of the presentation.
Presenter:
Ken Wyatt, Senior EMC Engineer, Wyatt Technical Services LLC
Kenneth Wyatt holds degrees in biology and Electronic engineering and has worked as a product development engineer for 10 years at various aerospace firms on projects ranging from DC-DC power converters to RF and microwave systems for shipboard and space systems. For over 20 years, he has worked as an EMC engineer for Hewlett-Packard and Agilent Technologies in Colorado Springs. He is currently an independent consultant with Wyatt Technical Services. A prolific author and presenter, he has written or presented topics including design of comb generators, DIY near-field and current probes, EMC troubleshooting and design of products.
Ken has been published in magazines such as Interference Technology, Test & Measurement World, Electronic Design, EDN, InCompliance and HP Journal. He currently authors The EMC Blog for EDN.com and coauthored The EMC Pocket Guide.
Ken is a senior member of the IEEE and a longtime member of the EMC Society where he has served as their official photographer. He is also a member of the dB Society and is a licensed amateur radio operator. His practical EMC design, measurement and troubleshooting seminars have been presented across the U.S., Europe and Asia.
Ken may be contacted directly at ken@emc-seminars.com. Further information on training opportunities, plus links to his technical articles, may be found on his web site: www.emc-seminars.com.
Question and Answer Session
Question: What you describe is good for big PC boards. How do you handle first EMC measurements for very small PC boards (like the size of a pencil)?
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Question: Our cables are folded and going in different directions in the instrument. Will they have both vertical and horizontal components of emissions, and is the emission frequency value dependent on the total length of cable, or is it only the length of cable that is horizontal (or vertical)?
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Question: For immunity, I thought an analog circuit was more susceptible than a digital circuit?
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Question: We typically use a 3m chamber to test our IVD instruments, as seems typical in the US and Europe. We were questioned by Japan as to why we do not use a 10 m chamber, since limits are in terms of 10 m in all of the standards, not 3m. How do we justify this?? Should final reports always be at a 10 m test site, not a 3 m chamber?
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Question: How do you troubleshoot frequencies above 1GHz?
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Question: What can you do if you notice the emissions noise is actually on the shield of the cable?
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Question: How do you validate the E-Field power level when using test antennas in a test bench area? For pre-compliance testing, how do you correlate your measured signal to compliance levels with homemade antennas?
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Question: When do we use an E-field versus a B-field probe for EMC testing?
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Question: I am confused about the purpose of the pigtail. What is the purpose or the point and why is it useful? What’s the recommended method in terminating cable shields?
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Question: I have some really sensitive pressure sensors and am picking a lot of noise from radiated frequencies on the immunity tests. I can see the 2Hz frequency on the product, as if it were the signal I am trying to measure! Even when shielding them with EMI plastic and/or metallic shields. These shields are not connected to ground nor earth, because doing that worsens the results. Maybe I am doing something wrong?
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Question: With high frequency these days, how can you have ventilation holes in your shield at 1/20 wavelength?
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Question: Where could I obtain the details of the PC antennas?
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Question: Are not inductive and capacitive coupling just special cases of radiated emissions? If so, then there are still only two types of coupling, right?
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Question: How do we minimize/eliminate radiated emissions for circuits with multiple ground returns?
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