Although L-shaped array can provide good angle estimation performance and is easy to implement, its two-dimensional (2D) direction-of-arrival (DOA) performance degrades greatly in the presence of mutual coupling. To deal with the mutual coupling effect, a novel 2D DOA estimation method for L-shaped array with low computational complexity is developed in this paper. First, we generalize the conventional mutual coupling model for L-shaped array and compensate the mutual coupling blindly via sacrificing a few sensors as auxiliary elements. Then we apply the propagator method twice to mitigate the effect of strong source signal correlation effect. Finally, the estimations of azimuth and elevation angles are achieved simultaneously without pair matching via the complex eigenvalue technique. Compared with the existing methods, the proposed method is computationally efficient without spectrum search or polynomial rooting and also has fine angle estimation performance for highly correlated source signals. Theoretical analysis and simulation results have demonstrated the effectiveness of the proposed method.
Many jamming methods have been proposed against displaced phase center antenna (DPCA) process, which is a type of three-channel synthetic aperture radar (SAR) ground moving target indication. However, two important problems faced by the jammer are why the jamming based on a single jammer is suppressed and how to generate noise in the whole DPCA image while keeping its easy realization. By analyzing a jamming geometric model based on a single jammer, the reason is that the phase of the jamming image in different antennas is only relative to the jamming geometric model, which contains the azimuth position of the jammer and jamming in the SAR image. Then, the jamming area is classified as an enhanced area and a weakened area after DPCA processing. Moreover, the jamming in the weakened area will be suppressed. To overcome this disadvantage, a barrage noise jamming method based on double jammers is proposed. By controlling the azimuth distance between the jammers, the noise can cover the whole DPCA image. Compared with the deception jamming method based on multiple coherent jammers, the phase and amplitude of the jamming signal do not need to be accurately controlled. Finally, the validity of the proposed method is verified by simulation experiments. INDEX TERMS Synthetic aperture radar (SAR), ground moving target indication (GMTI), displaced phase center antenna (DPCA), barraged jamming, double jammers.
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