Subband STAP Based on the Sparse Frequency Waveform for Airborne Radar in Dense Unintentional Jamming Environment

Compared with ground-based radar, airborne radar has excellent low-altitude moving target detection performance. With the development of economics, ground radiation sources are widely distributed, and the low-frequency spectrum is extremely crowded. When airborne radar operates over land, dense unintentional jamming can have a severe impact on target detection. The effects are mainly reflected in the following three aspects: 1) it is easy for jamming to enter from the main lobe and the main-lobe jamming is formed, which is difficult to be suppressed by traditional anti-jamming methods; 2) since the jamming distribution is dense, the degrees of freedom (DOFs) of jamming exceed the spatial DOFs of the system; and 3) jamming and clutter exist simultaneously and strong clutter is difficult to be suppressed effectively. In this article, a subband space-time adaptive processing (STAP) method for airborne radar based on the sparse frequency waveform is proposed. First, the jamming frequency and azimuth angle are obtained in the passive mode, and accordingly, the sparse frequency waveform is designed to suppress main-lobe jamming. Then, the echo data are divided into subbands, and each subband is processed by subband sidelobe cancellation processing to achieve the suppression of dense sidelobe jamming. Finally, the strong clutter is suppressed by STAP. The simulation results demonstrate that the proposed method has excellent performance in suppressing dense unintentional jamming and clutter.