Test results of a space-time adaptive processing system for airborne early warning radar

Space-time adaptive processing (STAP) has the potential to improve the performance of an airborne early warning (AEW) radar without the costly antenna refinements normally needed to reduce array sidelobes and, correspondingly, clutter. This paper presents a brief STAP overview and describes a radar system testbed which has been flown to gather data suitable for STAP algorithm development. The testbed consists of a 32 column by 8 row L-band array which feeds both conventional sum and delta analog beamformers as well as 22 independent subapertures. This configuration allows for the direct comparison of conventional and STAP beamforming. Measured data is shown which compares state of the art conventional beamforming with STAP processing. Whereas conventional sidelobes of -30 dBi were measured on a ground range, STAP processing of in-the-air clutter data demonstrated cancellation of as much as -45 dBi.