When Sensors Collide: The Looming Radar Interference Crisis in Autonomous Vehicles

One would think radar—battle-tested, weatherproof, and a darling of the ADAS sensor stack—would be the last thing to break down on the road to autonomy. But think again. As vehicles bristle with an ever-growing array of front, side, rear, and corner radar units, the invisible waves they emit are beginning to clash in unexpected and potentially dangerous ways.

This growing threat—radar-to-radar interference—is rapidly shifting from theoretical concern to real-world vulnerability. And while it's still under the radar for most consumers, leading automakers and defense contractors are sounding the alarm.

A Perfect Storm of Signal Saturation

Radar has long been praised for its robustness, as it performs well in darkness, fog, rain, and snow, making it indispensable for autonomous navigation. But as noted in EE Times’ recent deep dive, the very ubiquity of radar is creating its own downfall. “Radar interference is a growing challenge,” said Huanyu Gu, product marketing director for ADAS at NXP Semiconductors. “Passive techniques for interference avoidance, such as hopping the transmit frequency that may have worked in the past, won’t be sufficient with the growing number of radars on the road.”

The problem compounds in dense urban traffic, where closely packed vehicles—each equipped with multiple radar modules—can unintentionally interfere with each other. And it’s not just between vehicles. Self-interference among a car’s own radar sensors is also a growing headache, though comparatively easier to manage.

Why It Matters: Safety and Trust

According to Bitsensing CEO Jae-Eun Lee, “Radar-to-radar interference is more likely to occur in high-traffic, low-speed scenarios, such as traffic jams, where vehicle density is high and radar modules, especially front and corner units, are operating in close proximity.”

But it’s not just about complete signal loss. The insidious risk lies in subtle performance degradation—ghost echoes, missed detections, or poor object classification. These types of failures are notoriously hard to detect and debug, especially in complex edge cases.

“High-resolution imaging radar can be sensitive to interference,” Lee warned. “However, by implementing proven anti-interference techniques such as those used in conventional radar systems, we maintain stable performance in object detection and classification, even in complex environments.”  

The Defense Industry Gets Involved

This isn’t just a civilian problem. In January, Northrop Grumman and DARPA launched the $4.7 million COFFEE program (Compact Front-End Filters at the Element-Level) to develop a new class of compact, high-frequency radar filters for military AESA (active electronically scanned array) systems. The goal: to mitigate RF interference across 2–18 GHz and beyond.

These advances could trickle down into automotive applications—but only if startups and system integrators are ready to implement them at the chip level.

Enter Slip Signal: Mitigating EMI at the Source

Slip Signal Technologies is taking a fundamentally different approach. Rather than relying solely on waveform tricks or filter banks, Slip Signal is redesigning the substrate logic itself to eliminate electromagnetic interference (EMI) where it starts: inside the chip. Our patented (SEDL) technology shifts signal harmonics away from vulnerable RF bands, reducing emissions that cause radar cross-talk.

It’s a long shot—but rethinking digital logic at the substrate level may hold the key to protecting radar from radar. In vehicles where dense sensing and fast-switching logic collide, principles like SEDL deserve a closer look as a foundational approach to mitigating radar-to-radar interference.”

What’s Next?

While companies like NXP and Mobileye are refining on-device algorithms and adaptive modulation techniques, radar interference isn’t just a signal processing problem—it’s a systems engineering challenge. That’s why multiple strategies—from hardware design to real-time algorithmic compensation—must converge.

As NXP’s Gu aptly put it: “Interference that cannot be avoided has to be mitigated properly… especially in dense and complex environments.” As AVs inch toward Level 4 and robotaxis become a reality, the industry cannot afford to treat radar interference as a back-burner issue. Whether from a fellow commuter in the next lane or a drone overhead, tomorrow’s radars must navigate not just the world—but each other.