An Anti-Jamming SAR Method Based on Phase-Coded CP-OFDM Orthogonal Waveforms

With the development of digital technologies and radar systems， jamming techniques against synthetic-aperture radar （SAR） have undergone rapid advancement. In particular， deceptive jamming based on digital radio frequency memory （DRFM） poses an unprecedented challenge to SAR imaging systems. In this study， an anti-jamming SAR imaging method is investigated to counter this technique by integrating phase-coded waveforms with cyclic-prefix orthogonal frequency-division multiplexing （CP-OFDM）. A pulse compression method based on a linear model is introduced in the proposed phase-coded CP-OFDM orthogonal waveform to perform range processing on SAR echoes with the phase-coded waveform based on the cyclic prefix （CP） property； this enables autocorrelation pulse compression free from inter-range cell interference. Optimization of the time-domain phase coding enables improved cross-correlation performance among different waveforms. A p-norm multi-waveform weighted cyclic algorithm （p-WeCAN） is improved using the pulse compression method based on a linear model to optimize the phase-coded sequences of the set of CP-OFDM waveforms. The optimized waveforms achieved a cross-correlation peak sidelobe level approximately 2 dB lower than that of a randomly phase-coded CP-OFDM waveform set. The CP ensures good autocorrelation pulse compression performance， while the optimized phase-coding design provides favorable cross-correlation characteristics. Thus， the orthogonal waveform set can suppress deceptive jamming effectively in SAR imaging. Simulations were conducted to evaluate the capability of the proposed approach to defeat deceptive jamming against SAR imaging for extended and point targets as well as complex scenes reconstructed from echo data collected by the Gaofen-3 satellite in comparison with those obtained using linear frequency modulation pulses， and the results verified the effectiveness of the proposed approach.