Suppressing the false targets by time-modulated metasurface with pseudorandom-coded electromagnetic radar fields

Time-modulated metasurface can serve as a spoofing cloak partially covering on a static real target, thereby generating false targets in the high-resolution range profile (HRRP) and making the real target undetectable. This article proposes an electronic counter-countermeasure (ECCM) detection method to nullify the spoofing capabilities of time-modulated metasurfaces. The proposed method utilizes pseudorandom-coded (PC) radar signals that exhibit range-Doppler uncoupling characteristics, allowing for the preservation of static real targets while effectively suppressing false targets in the HRRP. Here, we first analyze the impact of the time-modulated metasurface on the reflected conventional linear frequency-modulated (LFM) signal and the proposed PC signal by using the 2-D correlation results (CRs) as a function of the time delay and Doppler shift. This analysis demonstrates how the range-Doppler coupling plays a role in the spoofing technique implemented by the metasurface. Then, the method’s effectiveness is experimentally verified using a 1-bit phase reconfigurable metasurface operating at 30 GHz. The results show that the PC radar signal significantly outperformed the LFM signal in suppressing false targets, making the real target well-detectable in the HRRP.