Passive radar is rapidly emerging as a transformative technology in the world of surveillance and air defence. Unlike traditional active radar systems, which transmit their own signals and analyse the reflections, passive radar leverages ambient electromagnetic emissions from sources such as radio towers, television broadcasts, and satellite constellations. This approach enables detection and tracking of objects without emitting detectable signals, making passive radar systems inherently stealthy, resistant to jamming, and often more cost-effective.
The evolution and significance of passive radar
While the concept of passive radar is not new, recent technological advancements have significantly enhanced its capabilities and broadened its applications. As electronic warfare becomes more sophisticated and the use of low-observable platforms like drones and stealth aircraft increases, the need for resilient and covert detection systems has never been greater.
Developments driving the field forward
Recent developments are at the heart of passive radar’s growing relevance and adoption:
- Operational trials and deployments: The German Air Force has been actively testing passive radar systems for air defence, demonstrating their ability to detect low-observable targets in complex environments. Estonia’s Defence Ministry has also adopted passive radar technology to reinforce border monitoring, particularly along its border with Russia, highlighting the technology’s value in national security.
- Urban and maritime applications: Passive radar is increasingly being explored for urban air defence and maritime surveillance. Its ability to operate effectively in environments with significant signal clutter—where conventional radar often faces challenges—makes it suitable for monitoring busy ports, city airspace, and remote coastal regions.
- Technological innovation: Advances in machine learning and signal processing are enabling more accurate detection and tracking, even as the electromagnetic environment becomes more crowded. Research institutions and industry players are developing new algorithms and sensor designs, further enhancing the performance and versatility of passive radar systems.
Why these developments matter
The recent surge in passive radar innovation is reshaping the landscape of modern defence. The technology’s inherent stealth, flexibility, and resilience make it an attractive option for addressing emerging threats. Passive radar systems can be deployed on fixed sites, mobile platforms, or vehicles, and are naturally resistant to jamming and spoofing. As the electromagnetic environment becomes more complex and contested, these qualities are increasingly valuable.
Key takeaway
The unique advantages of passive radar are shaping the future of surveillance, border security, and air defence, making it an area of growing importance for engineers, technologists, and defence professionals.
Learn more
The Institution of Engineering and Technology (IET) is offering a Passive Radar Technical Training Course on 3–4 December 2025. This virtual course, delivered by leading experts, covers both the fundamentals and the latest applications of passive radar, including its expanding role in defence and security: https://passiveradar.theiet.org/