Array configurations and space-time adaptive processing for spaceborne distributed GMTI radar

Ground moving target indication (GMTI) is an important, challenging application of space-based distributed aperture radars. Due to the large baseline of the sparse array, the main beam clutter Doppler spread can be reduced and minimum detectable velocity (MDV) can be improved. The cost is the blind zone problem introduced by spatial ambiguities and the grating lobes due to undersampling in spatial frequency domain. This paper investigates some solutions to the blind zone problem of space time adaptive processing (STAP) technique due to grating lobes and spatial ambiguities. In particular, the concepts of Minimum Redundancy Arrays (MARs) and Optimally Irreducible Arrays (OIAs) are introduced to STAP technique for space-based distributed aperture radars in order to solve the blind zone problem. We propose a method by using Optimally Irreducible Arrays combined with waveform diversity to improve the detection performance and present simulation results to show the effectiveness of the method.