Space-time adaptive processing for manoeuvring airborne radar

Space-time adaptive processing (STAP) methods are appropriate in airborne radar where, due to the platform motion, detection of target signals against a strong clutter background can be a significant problem. STAP has been mainly considered for SLAR (sideways looking airborne radar) where a linear relationship between the angular location and Doppler frequency of the clutter can be exploited to achieve clutter rejection and enhanced signal detectability via two dimensional filtering in the spatial and temporal frequency domains. Appropriate filters can be realised via the sampling of a coherent pulse train with a phased array antenna. Non-adaptive filter weight solutions which theoretically achieve full clutter suppression correspond to the well known DPCA (displaced phase centre antenna) technique. STAP offers the advantage over DPCA that the weights are calculated adaptively, leading to robustness to errors and a capability for simultaneous suppression of jamming and clutter. In contrast to SLAR applications, platform manoeuvre effects can be very significant in a forward looking radar. This is especially true of AI (airborne intercept) radar applications where the platform may be performing a steep dive or rolling at a significant rate. This paper demonstrates that STAP is applicable to a forward looking airborne radar operating in conditions that are far more demanding than considered previously