Stepped frequency chirp signal SAR imaging

To achieve high range resolution, using the stepped frequency chirp signal, two or more chirp waveforms are sequentially transmitted and received at stepped carrier frequencies in the whole bandwidth. An advantage of the approach has no increase in instantaneous bandwidth of the radar system. In this paper phase incoherent factor among sub pulses trains produced by down frequency conversion mixer is put forward and analyzed. Which must be took into account when range bandwidth synthesis is processed. Frequency domain bandwidth synthesis is applied to SAR imaging combining with the phase incoherent factor estimate and compensation based on contract optimization autofocusing. Simulation results show the validity of the method.