Azimuth Interrupted FMCW SAR for High-Resolution Imaging

Azimuth interrupted frequency modulation continuous-wave synthetic aperture radar (AI-FMCW SAR) is a novel type of light and miniaturized sensor that works on satellites, which can transmit and receive signals with a single antenna. Different from conventional pulse SAR, the instantaneous duty cycle of pulse is close to 100%. Several pulses could not be transmitted and would be replaced by receiving echoes. There will be gaps in the received echoes. It is necessary to reconstruct the gapped data; otherwise, there will be ghosting with traditional imaging algorithms. The current algorithms for reconstructing the gapped data are computationally time-consuming and not suitable for high-resolution imaging. Therefore, a new imaging algorithm is proposed to focus on the AI-FMCW SAR raw data via subaperture processing, which is called subaperature sparse reconstructing technique (SSRT). It can significantly suppress ghost targets and has a high calculation speed. In this letter, the spaceborne AI-FMCW SAR signal model was proposed first. Then, SSRT was proposed to process the AI-FMCW SAR data, in which the generalized orthogonal matching pursuit (GOMP) algorithm was used to reconstruct the signals. Finally, the simulation experiments verified the effectiveness and rapidity of the proposed approach.