A Fast Near-Field 3-D SAR Imaging Technique with Nonuniform MIMO Linear Array

This article presents a fast near-field 3-D imaging algorithm that can be applied to nonuniform multiple-input-multiple-output synthetic aperture radar imaging systems. The proposed method effectively overcomes the limitations of existing approaches, such as heavy computation burden and large approximation errors, providing an efficient and accurate imaging solution. First, the echo data is mapped to the wavenumber domain through phase correction filter, zero-padding, and fast Fourier transform (FFT). Then, phase multiplication and sparse matrix multiplication are employed to replace conventional interpolation and data reordering, effectively reducing computational complexity. To further enhance image quality, a coherence weighting factor is creatively introduced, significantly improving the signal-to-noise ratio of the reconstructed image. In the simulations and experiments, we compare with the back projection algorithm, multistatic scaling algorithm, and range migration algorithm based on nonuniform FFT, and the results illustrate the superiority of the proposed algorithm in terms of computational efficiency and imaging quality.