Every day our world becomes more saturated with electronic devices. And the products themselves are increasingly complex, cramming larger numbers of more powerful technologies into tighter spaces. But while this might be a boon for end users, it presents challenges for designers and manufacturers whose products need to pass Electromagnetic Compatibility (EMC) testing before they can hit the market.

“Electrification and digitalization are transforming entire sectors including electric vehicles, charging infrastructure, renewable energy systems, smart homes and smart factories,” says Dieter Fröhlich, MD of EMC lab technology at the CSA Group, which has EMC testing and certification facilities across North America.

And he believes: “Coexistence in dense electromagnetic environments is one of the key reasons why EMC testing has become more critical. For example, a modern car can contain hundreds of electronic control units, multiple high-power inverters, various radar and camera systems, and several wireless communication links. All of these must work simultaneously and reliably over many years, in diverse environmental conditions.”

Clearly, the days are long gone when you could simply wrap your consumer electronic device in a metal shield and hope for the best.

As José María Laborda, technical director at global testing, inspection and certification firm Applus+ Laboratories, says: “Higher switching frequencies, steeper edge rates, and mixed signal SoCs (systems-on-a-chip) increase both emissions and susceptibility, while miniaturized enclosures and cost-optimized designs limit the space available for filtering, shielding and grounding.”

As a result, he says: “Many issues that could once be solved at enclosure level now require EMC-aware PCB, power-distribution and firmware design from the outset.”

Lack of skills

However, these are issues for which many manufacturers are unprepared. As entire classes of existing products (and some that didn’t previously exist) suddenly find themselves crammed with electronics and even internet connections, firms may find they lack the skills to assess the compliance issues they face.

“Modern EMC requires cross-discipline knowledge (RF design, PCB layout, power

electronics, software, radios), and teams often lack experienced EMC engineers,” says John Michalowicz, senior RF test engineer at Arizona-based Compliance Testing.

As a result, product engineers may misjudge the standards they are achieving. “Confusion between pre-compliance measurements and full compliance results leads to false confidence,” he says.

Another issue is increasing supply chain complexity, with manufacturers incorporating ready-made, third-party components from a wide variety of sources into their products. This is common if, say, you feel the need to add WiFi or Bluetooth capability to an existing product line in order to remain competitive.

“COTS (commercial off-the-shelf) modules and sub-assemblies may carry unknown EMC behavior,” says Michalowicz. “Integrators must validate combined system effects.”

These combinatorial complications raise their own challenges. “Complex multi-board assemblies and embedded radios introduce aggregate emissions and non-linear behaviors that are difficult to predict,” Michalowicz says.

“The combination of higher digital edge rates (GHz-class clocks), mixed-signal circuits, and tight mechanical packaging increases both emissions and susceptibility, making early design practices and iterative pre-compliance testing essential.”

Stricter rules

Yet just as many firms find themselves having to meet compliance standards they’ve never encountered before, the rules themselves are getting stricter for everyone.

In particular, the scope of EMC compliance is broadening to encompass an ever-greater range of technologies and products. Where previously a product might have had to be tested for conducted/radiated emissions and immunity, it may now need to meet standards for wireless coexistence and over-the-air (OTA) testing.

“A good example is IEC 61000-4-3,” says Laborda at Applus+ Labs. “Older editions typically limited radiated immunity testing to 1GHz (or up to 2.5GHz in some product standards to cover 2.4GHz WiFi), because products seldom operated above those frequencies.

“As modern devices increasingly rely on newer WiFi, Bluetooth, cellular technologies, and other RF services at higher frequencies, the standard has evolved to support extended test ranges – in many cases up to 6GHz (and not limited to 6GHz, as higher ranges may be defined when required), which has become a widely adopted benchmark in many product standards.”

Increased test fidelity is another major pressure, particularly for wireless devices, as tests are now designed to more closely match real-world conditions. Michalowicz gives the example of MIMO (multiple input, multiple output) and OTA performance requirements, which focus on evaluating the efficiency and effectiveness of devices using multiple antennas.

And some domains may impose their own strictures. “In medical, for example, the trend is towards higher immunity expectations and more realistic test scenarios,” says Fröhlich. “This helps to ensure that life-support and diagnostic devices remain safe and effective, even in very harsh electromagnetic environments. In automotive, EMC is now tightly linked with functional safety.”

That need for safety is in turn driving a requirement for EMC limits and immunity levels that, says Michalowicz, “are generally more aggressive than consumer standards and explicitly address power-electronics disturbances from traction inverters and chargers”.

Product regulators, and many customers, now have higher expectations, and these are quickly enshrined in standards.

Michalowicz also points to IEC 61000-4-3 as an example of a commercial EMC standard that demands high RF-immunity levels, as well as the additional immunity tests required for safety-critical equipment.

Laborda adds: “One significant regulatory challenge today is the progressive expansion and overlap of EMC and RF-related requirements across sectors, driven by electrification and pervasive wireless connectivity. It is increasingly common for a single product to fall under multiple product standards simultaneously.”

And this pressure is made more onerous by the fact that you must comply not with just one local set of standards and regulations, but many.

Few manufacturers design products for a single market these days. And global distribution puts you at the mercy of multiple regulatory regimes, such as the FCC in the US, the Radio Equipment Directive (RED) in the EU, ISED in Canada, and so on.

Attitude problems

However, perhaps the biggest hurdle designers face is themselves – and specifically their attitude towards testing and compliance.

There are common errors that product engineers make. According to Fröhlich, these include: “Not reserving enough space for shielding and grounding concepts; mixing noisy and sensitive circuits on the same PCB area; poor cable routing and connector concepts; and a lack of consideration for worst-case operating modes during testing.”

He also raises the issue of an incomplete or outdated understanding of standards among designers. But worse still is the assumption that testing and certification can be some kind of tick-box exercise, left to the end of the development cycle.

“A frequent problem is treating EMC as a test event rather than a design discipline,” says Laborda. “Teams arrive at the laboratory with fixed mechanical constraints and no margin for EMC mitigation, resulting in avoidable failures.”

EMC planning needs to be done in the early stages of a project. Yet steps such as PCB layout, grounding strategies, and internal cable routing are carried out in an ad hoc, per-device basis, rather than being implemented in a consistent and disciplined way across all of a manufacturer’s products. This is particularly true in fast-moving sectors like consumer products.

Having a standardized approach that has been shown to work on successful projects can help avoid many testing headaches, and speed time-to-market.

No-one is saying that product designers should be EMC experts. They can’t be, because this is a specialist area and one where the goalposts are constantly shifting. Those companies that are specialists in EMC testing are constantly innovating and introducing new capabilities in order to keep up.

For example, advancing wireless technologies have led to the introduction of a broader and more complex suite of test methods.

“Beyond MIMO, OTA and spatial performance measurements, newer regulatory mechanisms – such as Automated Frequency Coordination (AFC) for 6GHz devices and enhanced Dynamic Frequency Selection (DFS) requirements in 5GHz – are adding substantive test obligations,” explains Michalowicz.

Among the capabilities developed by EMC testing firms, he highlights:

– Expanded reverberation chamber and Compact Antenna Test Range (CATR) capabilities for OTA and MIMO testing.

– Automated pre-compliance test suites and turnkey pre-scan services (including near-field probes and radiated pre-scans) to catch problems earlier.

– Advanced near-field measurement tools and imaging to localize hot spots on PCBs and cables quickly.

– Hybrid test setups that combine conducted and radiated methods, and bench-level immunity simulators that emulate real-world disturbances.

– Faster test automation and data analytics, such as scripting, databases of failure modes, and digital reporting to shorten iteration cycles.

– System-level and in-vehicle test capabilities with representative harnesses, loads and DUT (device under test) mounting fixtures.

Along with these capabilities come new and expanded services, such as coexistence testing, wireless performance in contested spectrum, and consulting to help guide designs from an early stage. As Michael Schafer, CEO at Compliance Testing, argues: “Design engineers ought to reach out to their test lab for guidance and support if they feel they do not know the regulatory requirements they will need to meet.”

Indeed, manufacturers can effectively tackle all of these challenges by taking advantage of that guidance, and integrating EMC considerations as a key element of product design.

According to Fröhlich: “The good news is that manufacturers who treat EMC as a design can still achieve fast and reliable certification.”