When the airborne or missile borne radar works at the forward-looking imaging mode, the common techniques for improving azimuth resolution are invalid, because the difference between the Doppler frequencies of targets in different azimuths is very small. Meanwhile, other real beam sharpening methods only have very limited effect on azimuth resolution enhancement. For the problem of forward-looking imaging of ship targets at sea surface, a L1/2regularization based azimuth resolution enhancement algorithm is proposed in this paper. This algorithm can make full use of the obvious sparsity in the imaging area. The linear observation signal model for forward-looking imaging is built, and the iterative calculation process of L1/2regularization and the detailed steps of multi-channel radar forward-looking imaging are provided in this paper. Finally, the effectiveness of the proposed algorithm is tested and verified with simulation data and real data.

As a new application platform of synthetic aperture radar (SAR), the near-space hypersonic vehicle has a more serious range migration problem than the traditional airborne platform due to its curved-flight motion characteristic, and its imaging results will be further affected under the condition of high resolution demand. Since the SAR slant range of hypersonic platform is relatively complicated, the azimuth and range in the two-dimensional spectrum obtained by means of traditional wavenumber domain imaging algorithm are mutually coupled. As a result, it is difficult to accurately correct the range migration by interpolation operation. Therefore, an improved wavenumber domain imaging algorithm is proposed in this paper. Through the appropriate approximation of the two-dimensional spectrum of the SAR echo signal, the reference function is designed and the well focus of targets in the observation scene is achieved by the Stolt interpolation. Finally, simulation results are given to verify the effectiveness of the algorithm.