| Summary: | Micromotion targets can enable microDoppler modulation on electromagnetic waves owing to their motion components in different directions, resulting in the defocusing effects of the target imaging features along the azimuth direction. This phenomenon has been widely considered and investigated in target recognition and antirecognition. As a research hotspot, electronically controlled time-varying electromagnetic materials have fast modulation characteristics; however, their imaging characteristics have not received much attention. This study investigates the Synthetic Aperture Radar (SAR) modulation characteristics along the range direction of electronically controlled time-varying electromagnetic materials. Then, this study establishes the time-varying electromagnetic material spectrum transformation model and analyzes the SAR target characteristic control principle. Taking the Phase-Switched Screen (PSS) as an example, a nonperiodic PSS phase modulation model is established, and its spectrum has continuous frequency shift characteristics. On this basis, the influence of continuous frequency shift modulation induced by nonperiodic PSS on SAR was further discussed and the defocusing phenomenon of the target along the range direction was detected. Through the simulation of measured data, the validity of the proposed theoretical method is verified.
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