Metasurface‐Enabled Active‐Like Passive Radar

ABSTRACT Passive radars (PRs) provide a low‐cost and energy‐efficient approach to object detection by reusing existing wireless transmissions instead of emitting dedicated probing signals. Yet, conventional passive systems require prior knowledge of non‐cooperative source waveforms, are vulnerable to strong interference, and rely on Doppler signatures, limiting their ability to detect subtle or slow‐moving targets. Here, we introduce a metasurface‐enabled PR (MEPR) concept that integrates a space‐time‐coding programmable metasurface to imprint distinct spatiotemporal tags onto ambient wireless wavefields. This mechanism transforms a PR into an active‐like sensing platform without the need for source control, enabling interference suppression, signal enhancement, and accurate target localization and tracking in cluttered environments. A proof‐of‐concept implementation operating at 5.48 GHz confirms real‐time imaging and tracking of unmanned aerial vehicles under interference‐rich conditions, with performance comparable to active radar systems. These results establish MEPR as a solid foundation for scalable, adaptive, and energy‐efficient next‐generation integrated sensing and communication systems.