The development and application of the multi-channel Synthetic Aperture Radar (SAR) have greatly enhanced the information acquisition and anti-jamming capabilities of the imaging radar and led to its development direction. Compared with the traditional SAR, the multi-channel SAR can extract more useful information from the phase of echo signals and has a higher degree of freedom. As one of several types of mature multi-channel techniques, SAR multi-channel cancellation technique can suppress various kinds of jamming signals, including scatter-wave jamming signals, by using the phase relation of jamming signals received by different channels, making it an efficient and direct type of anti-jamming method. In the process of multi-channel cancellation, the phase difference of jamming signals reaching different channels can be generally estimated by the automatic phase searching algorithm, and then the phase difference is used for compensation to finish the jamming signal cancellation. At present, regardless of the channels distributed along the track or across the track, multi-channel SAR systems can employ this anti-jamming technique. However, jamming technology against multi-channel cancellation has rarely been researched. Therefore, a cosinusoidal phase-modulated scatter-wave jamming method aimed at countering the multi-channel cancellation technique is proposed in this paper. First, multi-channel cancellation theory of traditional scatter-wave jamming is analyzed through the dual-channel cancellation technique, and the process of automatic phase searching algorithm based on the rule of minimum energy is summarized. Second, the cosinusoidal phase-modulated signal model is presented and used to improve the traditional scatter-wave jamming signal. Cosinusoidal phase modulation in slow time directly leads to the Doppler spectrum moving and the extension of jamming in the azimuth, according to which the imaging characteristic of the novel jamming signal for SAR is analyzed in detail. Then, the effect of the proposed jamming method working on the dual-channel cancellation system is derived and analyzed. Cosinusoidal phase modulation severely changes the original phase difference, which exerts an effect on the automatic phase searching link to alter the estimated results of the compensation phase in the cancellation process. The changed compensation phase will seriously destroy the real scene imaging. Finally, the simulation experiment results and analysis are presented in which four groups of jamming parameters are set and compared to verify the controllability of jamming. Theoretical analysis and experiment result show that the proposed jamming method can produce multiple false scattering scenes in traditional SAR imaging. In the dual-channel cancellation process, this method causes the estimated compensation phase to vary with slow time sinusoidally. It also causes the real scene image to move repeatedly, which leads to serious image overlapping and produces many dark and bright speckles distributed along the azimuth. The jamming effect can be controlled by setting different jamming parameters, such as modulation frequency and so on. The proposed jamming method is flexible, controllable, and has good stealthiness. It can deactivate the multi-channel cancellation jamming suppression and enhance the jamming effect by utilizing the characteristics of the cancellation process. Importantly, the jamming signal after phase modulation in the azimuth can influence the extraction result of phase information of the signal received by the multi-channel SAR system. Such effect can provide additional ideas and methods for multi-channel SAR jamming research.

synthetic aperture radar (SAR);dual-channel cancellation;scatter-wave jamming;cosinusoidal phase-modulated;compensation phase;electronic countermeasures (ECM)