Imaging for MIMO Sliding Spotlight SAR Using Stepped Frequency Chirps

To achieve two-dimensional ultra high resolution and wide swath, this paper applies the stepped frequency chirps to the MIMO sliding spotlight SAR, where each subaperture transmits a different subband. During the imaging, multichannel reconstruction and bandwidth synthesis are embedded into the "two-step" focusing approach. Since the frequency range for each subband is different, a range-frequency-dependent reference function (FDRF) combined with chirp z-transform (CZT) is employed during the azimuth preprocessing. Moreover, the FDRF removes the residual Doppler bandwidth introduced by deramping with a range-frequency-independent reference function (FIRF). Simulation experiment is performed to validate the presented imaging approach.