Stepped frequency SAR imaging based on compensation in Doppler domain

The application of stepped frequency waveform in synthetic aperture radar (SAR) can greatly reduce the hardware requirements, while obtaining high range resolution. However, the range difference within a single stepped-frequency burst may cause the range profile shift and defocus, which seriously affect the quality of SAR image. Traditional compensation methods for this problem are rather complicated. In order to achieve effective and rapid two-dimensional imaging, a SAR imaging algorithm for stepped frequency radar based on compensation in Doppler domain is proposed. Firstly, the stepped frequency SAR echo model is established, and the slant range is simplified in this article. Then azimuth spectrum expression is deduced by the principle of stationary phase (POSP), afterward a compensation function is used to compensate the azimuth spectrum. Finally, a two-dimensional IFFT and target extraction are performed to obtain the high resolution image. Simulation verifies the validity of the algorithm.