Clutter Suppression for STAP-Based Radar Using Synthesized Subarray Beampattern

The space-time-coupled grating lobe clutter (GLC) usually exists and is difficult to handle for subarray-based phased array airborne radar, which would cause serious performance degradation in clutter suppression. To alleviate this problem, this article presents a data-independent subarray beampattern synthesis approach for the space-time adaptive processing (STAP) based radar. In particular, the GLC spectrum is first analyzed in detail, based on which the receive overlapped subarray beampattern is designed with certain nulls located at the grating lobe regions to prefilter of GLC. During the GLC suppression, the subarray beampattern synthesis algorithm is devised based on the criterion of maximizing array gain, where phase ambiguity is incorporated into the optimization model to precisely adjust the power responses of the receive subarray beampattern. In this way, the GLC can be prefiltered in subarray and its coupling diffusion characteristic in the space-time domain can be prevented, thus improving the clutter suppression and moving target detection capabilities. In what follows, the subarray-level STAP filter is implemented for the residual space-time coupling mainlobe and sidelobe clutter suppression. Numerical results demonstrate that the proposed subarray beampattern synthesis method can remarkably enhance the output signal-to-clutter-plus-noise ratio loss performance in GLC regions.