Abstract:The passive distributed microsatellites Synthetic Aperture Radar(SAR) system has the capabilities in improving image resolution, detecting ground moving targets and computing digital elevation models. But the input Signal-to-Noise Ratio (SNR) of the system will largely reduce compared with the active spaceborne radar because of the decrease of its receiving antenna’s area, which will degrade the performance of the system. This paper analyses the effect of the SNR’s reduction on SAR imagery, Digital Elevation Model (DEM) and Ground Moving Target Indication (GMTI), based on the JERS-1 acted as the active satellite, and comes to a conclusion that the SNR obtained from the system would be lower than what the system required. Some methods to improve the system’s output SNR by coherent or noncoherent operating are also discussed.