Direction of Arrival Deception With Time-Modulated Scatterers

Modern radar systems can detect targets with high accuracy and are even able to classify them remotely. Their continuous advance is inevitably met with developing radar countermeasures, where passive radio-silent countermeasures begin to prevail over active jamming approaches. The direction of targets in respect to a radar system can be deduced from the correlation between the sampled phases in different antennas forming a receiving array. By breaking this coherent relationship, it is possible to cause the radar to estimate the wrong direction of arrival, deceiving it into concluding the object is elsewhere. A method for achieving this by controlling the reflected phase from a time-modulated scatterer is presented both theoretically and experimentally, showing suitability for implementation via time-dependent metasurfaces, supporting a semi-passive (battery-assisted) mode of operation. The method is also well suited for long range angular deception, complementing ’cross-eye’ jamming techniques that are most effective at short ranges. We demonstrate control over the radar-perceived angular location of the static concealed target, with proven ability to steer the direction of arrival on demand by over 5 degrees away from its true angular position regardless of range. Remarkably, this new type of electronic countermeasure works better with increasing radar bandwidth, turning its strength into an exploitable weakness.