The algorithms of blocking matrix preprocessing (BMP) and eigen-projection matrix preprocessing (EMP) to suppress mainlobe interference will lead to the main peak offset. Aiming at dealing with the problem, the conventional methods, such as diagonal loading, diagonal loading combined with linear constraint, whitened, and weight coefficient compensation are used. Guided by the eigen-projection and L2 norm constraint, this paper presents a novel method based on blocking matrix preprocessing and L2 norm constraint. The improved BMP algorithm not only can overcome the deviation of the peak value, but also can achieve excellent performance at low snapshots in comparison with traditional methods. Besides, the accurate direction of sidelobe interference is not required, so the improved method is easy to implement in engineering. The biggest advantage is that the proposed method can maintain the high output signal to interference-plus-noise ratio (SINR) in the case of strong mainlobe jamming. Theoretical analysis and simulations demonstrate that the proposed method has the optimal performance for mainlobe jamming suppression.
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