Synthetic bandwidth method for SAR in deramp-on-receive mode

As current airborne SAR systems aiming to produce SAR imagery at resolution less than 0.1 m, attaining ultrawideband signal become a difficult problem. Synthetic bandwidth based on frequency-stepped chirps is an available method to achieve this type of ultra-wideband signal, the advantage of which is the reduction of the instantaneous bandwidth and sampling rate requirements of the radar system. This paper analyzed the synthetic bandwidth method for deramp-on-receive signal in detail. To evaluate the capability of this method, simulations were carried out. For the lack of real deramped frequency-stepped chirps SAR data, we proposed an approach to transform the common non-deramped total bandwidth SAR data to deramped frequency-stepped chirps data, then process the transformed data with synthetic bandwidth method, and the imaging results show the validity of the proposed method.