| Summary: | Vortex electromagnetic (EM) wave has shown great potential in the field of radar imaging. Under the assumption that the target is located at the grid point, the compressed sensing (CS) algorithm is applied to vortex EM imaging and achieves high imaging quality. However, the off-grid target in the actual scene deviates from the grid points, resulting in the basis mismatch problem. This problem will lead to the mismatch between the assumed measurement matrix and the real echo signal and the degradation of the CS imaging performance. In order to solve this problem, a novel two-dimensional (2-D) joint off-grid imaging method is proposed by considering the gridding error as a multiplicative matrix and separating it via series expansion. This method compensates for errors in 2-D matrix directly instead of converting the 2-D matrix into the 1-D vector, which can not only solve the off-grid problem, but also reduce the storage of data acquisition and processing. Furthermore, the 2-D iterative adaptive algorithm (2DIAA) for the 2-D model is adopted to achieve better reconstruction performance and lower computational complexity. Finally, Simulation results show the effectiveness and robustness of the algorithm.
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