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Why Perform EMI/EMC Testing?

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by Reyes Cortes, Manager of Electrical Testing, Dayton T. Brown, Inc.

Reyes Cortes

EMI or EMC testing is essential for modern electronic devices to determine if the device can operate within its intended setting (environment) and in accordance with required standards.

Modern electronic devices must operate in today’s environments which are surrounded by multiple radio waves and electromagnetic (EM) energy. The device may even contribute to the amount of EM energy in the environment, in which case it is guilty of causing electromagnetic interference (EMI). For an electronic device or system to operate properly under such conditions, it must have electromagnetic compatibility (EMC) with its operating environment.

EMC is important for many electronic designs and especially critical for military, aerospace, and medical electronic  applications, where lives may be at stake. Test standards have been developed over time to monitor and maintain acceptable EMI and EMC levels. Applying these EMI/EMC standards to a new or existing electronic product requires well-equipped test facilities and the engineering personnel with the expertise to evaluate the EM behavior of a device under test (DUT), unit under test (UUT), or equipment under test (EUT). Dayton T. Brown (DTB) has both the facilities and the engineering experience, offered in the form of complete EMI and EMC testing services to prepare modern electronic devices and equipment for problem-free operation in today’s EM environments.

What is EMI/EMC Testing?
EMI and EMC testing determines how EM energy can enter and escape from the EUT. EM energy propagates through the air, as radio waves, and travels through cables, wires, and other conductors, so that at least four different EM measurements are performed to determine different EM levels: conducted emissions (CE) and conducted susceptibility (CS) for cables and radiated emissions (RE) and radiated susceptibility (RS) for EM energy that may be escaping from or entering, respectively, the EUT over the air.

Guidelines for EMC Testing
Federal Communications Commission (FCC) Part 15 rules define the limits for unlicensed RFI that can be produced by consumer electronics and other devices. For military requirements, EMI and EMC measurements are usually performed according to the guidelines of MIL-STD-461 and MIL-STD-464, which outline EMC and environmental requirements for components/subsystems and systems for military applications. In the U.S. commercial market, EUT measurements are usually performed according to the guidelines of RTCA DO-160. International EMC and EMI measurements may refer to the International Electrotechnical Commission International CISPR (such as CISPR 22) and the International Electrotechnical Commission (IEC) standards, such as IEC 61000. Differences exist in the terminology among standards, with international standards referring to immunity rather than susceptibility as in U. S. standards.

Efficient EMI/EMC testing calls for high-performance test equipment and the people who know how to use it. It also requires effective test environments, well isolated from the world’s many sources of EM energy, from cell phones to radio towers. Shielding a test environment is not easy, especially as EM sources move higher in frequency, into the mmWave range with 5G wireless networks, collision-avoidance radars, and satcom systems. A shielded test environment must be large enough to accommodate an EUT yet provide the flexibility to rotate an EUT 360 degrees for full radiated emissions and susceptibility testing. DTB relies on more than 12 shielded facilities and more than 75 years of testing history to accommodate a broad spectrum of EUTs.

Who Should Care?
EMI is a problem that affects all users of electronic devices, not just the military. As the EM spectrum grows more congested with time, EMI and EMC testing becomes more important to ensure the “peaceful co-existence” of electronic devices within the operating environment. Excess EM energy levels can degrade the reliability of an electronic design, causing damage to susceptible integrated circuits (ICs) within its PCBs. EMI/EMC testing provides a way to foresee the behavior of an electronic design in controlled test environments and under conditions as close as possible to the actual operating environment.

The extensive knowledge and experience of DTB’s test engineers can simplify any preparations as part of the EMC pre-compliance or compliance processes. DTB can also ease EMC testing by explaining which EMC test standards apply to a particular EUT and which EM emissions and immunity tests apply to the EUT, such as standards from CISPR and IEC 61000 from the International Electrotechnical Commission (IEC).

Although causes for EMI are many and reasons for failing to achieve EMC may be even greater, DTB equips their experienced, knowledgeable test engineers with well-shielded anechoic chambers of various sizes and a full array of measurement instruments and tools under one roof for a wide array of EMI/EMC tests on EUTs for of all kinds for aerospace, automotive, commercial, medical, military, and space markets.

Who Can Help with Testing?
DTB shielded enclosures are large enough for complete system testing, even when the EUTs are contained within larger “containers,” such as vehicles. Test chambers are constructed with pyramid-shaped EM absorbent material to minimize unwanted EM levels (Fig. 1).

The DTB test chambers are well supported by the latest standard and custom test instruments for the generation and analysis of conducted and radiated EM emissions through 40 GHz. Test instruments include CW and pulse test signal sources to produce any combination of continuous, modulated, and random signals, standard and real-time spectrum analyzers with specialized accessories, such as EMI filters, for detection of custom signals, and EMI receivers capable of broadband frequency coverage. Aided by a wide range of test antennas and instrument-grade power amplifiers, DTB’s EMI/EMC test sets can generate EM radiated susceptibility fields more than 200 V/m.

Given the increasing consumption of bandwidth by modern electronic devices, EMI/EMC testing can be considered an automatic part of every new electronic product development. As the U. S. DoD seeks to take advantage of 5G cellular wireless networks and interconnected Internet of Things (IoT) sensors to improve logistics at military bases and depots, the importance of EMI/EMC for all involved electronic devices cannot be emphasized enough. Fortunately, DTB brings the experience, facilities, and tools to deliver the highest-quality EMI/EMC testing as needed for future supply-chain automation that will be reliable, safe, and secure.

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