A prototype for stepped-frequency SAR dechirp imaging system and experimental verification

In SAR imaging, range resolution is inversely proportional to the transmitted signal bandwidth. Generally, for technological or cost reasons relative to radar hardware, the ability to produce or receive wide bandwidth signal is limited. However, if the frequency band of the transmitted signal is skipped within a train of sub-pulses and the received signals are properly combined, then the signal bandwidth could be effectively increased, as well as the range resolution could be improved. The proposed system indeed breaks through the limitation in range resolution which is set by the radar hardware units in traditional method. Synthesized processing of stepped-frequency chirp subpulses makes SAR range resolution much higher. The experiment has been conducted successfully and the improvement on range resolution is verified.