Two Dimensional Resolution Improvement for FMCW Synthetic Aperture Radar Using Multistatic Configuration

Frequency-modulated continuous wave (FMCW) synthetic aperture radars (SARs) mounted on lightweight platforms cannot have highly resolved range and azimuth resolutions owing to hardware limitations such as load and power consumption. To overcome this, we propose a two-dimensional resolution improvement method using cross-track and along-track interferometry for range resolution improvement (RRI) and azimuth resolution improvement (ARI), respectively. First, RRI is performed for the FMCW SAR by combining two deramped FMCW signals depending on the spectral shift caused by the cross-track interferometry (CTI) configuration. Subsequently, for ARI, the Doppler frequency spectra of the signals are combined considering the difference between the Doppler centroids. Thereafter, a SAR image with improved range and azimuth resolutions can be generated. The simulation results verify the effectiveness of the proposed RI method in terms of resolution values; particularly, the proposed method can find adjacent point scatterers, which do not appear in conventional SAR images because of poor resolution.