Subsection-Shift-Doppler-Frequency Jamming Based on Phase-Tunable Metasurface Against SAR Imaging

It is a challenging task to design a passive jamming method capable of both high fidelity and flexibility against synthetic aperture radar (SAR) imaging. Motivated by recent advances in the electromagnetic metasurface technique, a novel subsection-shift-Doppler-frequency jamming method based on the phase-tunable metasurface is proposed for the SAR system. Inspired by the realistic interference effects of the shift-frequency and segmented modulations, the proposed method flexibly imposes the subsection-shift-Doppler-frequency modulation on the SAR echo by the phase-tunable metasurface loaded with varactor diodes, which is designed to realize the continuous and real-time phase modulation through an external control system. Consequently, multiple false targets with flexible and controllable azimuth positions and verisimilar topological structures are generated instead of the protected target after receiving and processing the jamming signal by the victim SAR system. The influence of the phase-tunable metasurface modulation parameters on the jamming imaging effect is derived in theory. Simulations and experiments on satellite RadarSat-2 data are performed to verify the effectiveness of the proposed method. The theoretical analysis and experimental results show that the proposed method achieves the jamming imaging performance with high fidelity, high flexibility, low zero power, and low cost, effectively combining the advantages of traditional active and passive jamming.