If your wireless product has recently failed EMC testing, particularly in the 2.4 GHz band, you’re not alone.

Across the industry, manufacturers are seeing an increase in failures under the latest revision of EN 301 489-17. Products that previously passed are now struggling to meet requirements, often late in the development cycle.

We’ve been working closely with customers experiencing these issues, and while each case is different, clear patterns are emerging.

What’s Changed?

The latest update to EN 301 489-17 doesn’t just refine limits, it changes how devices are evaluated and tested.

Test labs are increasingly:

• Exercising devices in realistic, worst-case operating modes
• Evaluating continuous and high-duty-cycle transmissions
• Expecting performance under simultaneous or stressed RF conditions

In short, devices are no longer tested in “ideal” scenarios; they are evaluated under more demanding and representative conditions, with limited tolerance for errors, even those that rarely occur in real-world use.

Silex Insight and Observation

In some cases, we’ve observed an interesting behavior during EMC and wireless performance testing: a device performs as expected when operating close to an access point, but shows degradation as the distance increases.

While this isn’t a universal pattern and shouldn’t be taken as a definitive root cause, it can be a useful factor to examine when isolating contributors to packet error rate (PER) degradation. Changes in signal strength, noise susceptibility, and system sensitivity at range can sometimes reveal underlying vulnerabilities that aren’t apparent under stronger signal conditions.

At first glance, this seems counterintuitive, but it highlights an important aspect of modern wireless systems.

Wireless modules dynamically adapt their behavior based on link conditions. As signal quality degrades, the system typically shifts to more robust, lower data rates, which help maintain a reliable connection but also result in longer transmission times. Retransmissions may also increase under these conditions.

While these adaptations improve link stability, they can increase overall airtime and alter RF activity in ways that may be more likely to expose EMC-related issues. It’s important to note that this behavior is not driven by increased transmit power, but by how the system balances reliability and efficiency under less favorable signal conditions.

Why This Matters Now

Historically, many pre-compliance setups unintentionally tested devices under favorable conditions:

• Strong RF link
• Lower transmit power
• Shorter transmission bursts

Under the updated expectations of EN 301 489-17, those conditions may no longer represent the worst case. As a result, issues that were always present but hidden are now being exposed during formal testing.

What This Means for Product Developers

The key takeaway is that EMC performance is no longer just about the module.

It is a system-level challenge involving:

• Host PCB layout
• Power supply design
• Antenna integration
• Firmware and driver behavior

Even when using pre-certified wireless modules, the final product must be evaluated under realistic operating conditions.

How We’re Helping Our Customers

While root causes can vary, we’re working with customers to reduce risk early in the design cycle by focusing on three key areas:

1. Defining Worst-Case Operating Modes

   We can help identify and reproduce conditions that represent maximum RF stress, ensuring issues are found before formal testing.

2.  Improving System-Level Design

   We can provide guidance on layout, grounding, and power design to minimize unintended emissions. We use our modules in our own products, so we can share and guide from our experiences. By working across multiple products and use cases, we can highlight common failure patterns and practical mitigation strategies.

Implications of the Updated EN 301 489-17

The latest evolution of EN 301 489-17 reflects a broader shift in the industry—from testing theoretical operation to validating performance under real-world conditions.

For product teams, this means EMC can no longer be treated as a final checkbox; it must be considered throughout the design process.

With the updated standard coming into effect on June 30, 2026, all products placed on the European market will need to comply with the revised requirements.

Need Support?

Unexpected EMC failures can be frustrating, especially when they appear late in the process and disrupt certification timelines. While resolving these issues can be complex, particularly for products developed outside our direct design scope, we aim to be a valuable partner in navigating the challenge.

In many cases, visibility into a product’s full design is limited, which naturally constrains how deeply we can diagnose or resolve issues. However, that doesn’t mean you’re on your own. We can offer informed, third-party perspectives, share relevant experience from similar scenarios, and help identify potential risk areas or worst-case conditions that may be contributing to the problem.

Have you encountered similar challenges with your wireless designs? We’d be interested in hearing your experience at sales@silexamerica.com.