Bistatic SAR Imaging with NLFM Range Migration Algorithm and Chirp Polarity Modulation

This paper presents a range migration algorithm (RMA) for bistatic synthetic aperture radar (SAR) based on nonlinear frequency modulation (NLFM) with polarity agility in frequency coefficient modulation. Traditional SAR imaging techniques typically employ linear frequency modulation (LFM) signals, but these methods often lack sufficient anti-jamming capabilities in complex environments, particularly under delayed retransmission interference. To mitigate this limitation, polarity-agile frequency coefficient modulation is applied, utilizing the nonlinear properties of NLFM signals to improve interference suppression and imaging accuracy. Results from multiple point target imaging experiments and delayed interference simulations confirm that the proposed algorithm distinguishes effectively between interference and true echo signals, significantly enhancing imaging reliability and anti-jamming robustness. In high-interference environments, the algorithm effectively suppresses false targets, greatly improving imaging precision. This approach offers an innovative and practical solution for bistatic SAR imaging in complex scenarios characterized by delayed retransmission interference.