Abstract: The ambiguity problems of space based GMTI (Ground Moving Target Indication) radar using sparse arrays have been greatly concerned. To solve the blind-zone problem of moving target detection induced by angle ambiguity and Doppler ambiguity, an idea of the minimum redundancy is applied to array designs for radar, for a restricted element number, two minimum redundancy array configurations are presented, which can effectively mitigate the contradiction between the unambiguous velocity rang and the velocity resolution, as well as improve the angle ambiguity induced by sparseness. Taking Doppler ambiguity into account, the model of minimum redundancy array radar systems with multiple carrier frequencies are founded。Simulation results are given to demonstrate the effectiveness of space-time-frequency adaptive processing in improving Doppler ambiguity and GMTI performance