Diverse Frequency Time Modulation for Passive False Target Spoofing: Design and Experiment

This article presents a new design of diverse frequency time modulation for linear frequency-modulated (LFM) radar passive false target spoofing. To realize the passive diverse frequency time modulation, the modulated metasurface is designed accordingly, which is composed by a set of elements, each of which is independently time-modulated to realize specific false targets in the high-resolution range profile (HRRP) of the radar system. Due to the control of the modulation scheme in each element and the combined response of the overall surface, we demonstrate the capability to realize several false target patterns consisting of single and multiple targets symmetrically or, asymmetrically, distributed around the actual target. An HRRP general expression of the time-modulated diverse frequency metasurface at different observation angles is given to show the relation between the generated false targets and frequency components. Since having more flexible capacity of reflected signal manipulation compared to false target spoofing only through time modulation with consistent modulation frequency, the proposed method has enhanced performance on control of false targets at different observation angles. Both simulated and measured results demonstrate the validity of false target manipulation, demonstrating its effectiveness as electromagnetic countermeasure for achieving radar camouflaging and deception.