Short-range clutter suppression based on subspace projection preprocessing for airborne radar

For non-side-looking airborne radar, the azimuth-Doppler clutter spectrum varies with elevation angle, creating range-dependent clutter statistics. Generally, short-range clutter statistics vary rapidly with range while long-range clutter statistics vary slowly. In the range ambiguity case, the problem of clutter non-stationary becomes even worse, and classical space-time adaptive processing (STAP) algorithms suffer serious performance degradation. With the assumption of using a rectangular array, a subspace projection preprocessing scheme is proposed. In this technique, we first estimate the subspace corresponding to the short-range clutter in the azimuth-elevation domain for each range cell, and then the short-range clutter is eliminated by subspace projection processing in the same domain. After that, the rectangular array data are synthesized into a linear array data, and the classical extended factored approach is adopted to cancel residual clutter. Simulation results demonstrate that the clutter range dependence can be effectively alleviated by the proposed scheme, and the STAP performance is enhanced.