Aimed at continuous scene imaging, this paper utilizes signal reconstruction method to eliminate random phases of scatter cells and reduce signal bandwidth, to achieve downward-looking 3D imaging in the condition of sparse flight for array SAR. With the sampling method of repeat flight such as 7 dense flights and 4 sparse flights with sampling criteria of [1 1 1 0 0 1 0] (Barker code sequence), [0 1 1 0 1 0 1] and [1 0 1 0 1 0 1] (uniformly-spaced sequence), respectively, the 3D imaging simulation is implemented in this paper. In addition, we compare the imaging quality before and after signal reconstruction. Simulation results illustrate that the adoption of signal reconstruction can significantly improve image quality; the combination of Barker code sparse flight and signal reconstruction presents the best performance among all the implemented methods.

An airship sparse array antenna radar system is investigated in this paper. The performance of the sparse array antenna is compared to the conventional dense array antenna. Ground moving target indication (GMTI) and real aperture radar (RAR) imaging mode are discussed. Some important parameters such as resolution and signal-to-noise ratio (SNR) of airship radar system are studied to prove the feasibility of the airship-mounted radar system.

This paper analyses the sparsity of SAR signal under the multi-antenna observation structure. Based on the sparsity of continuous scene spectrum and sparsity of target scene, a down-sampling method is proposed and side-looking 3D imaging of cross-track sparse array SAR is investigated. Imaging results on simulation and real data are given to verify the proposed method.

Side-looking three-dimensional (3D) imaging of cross-track three-aperture sparse array synthetic aperture radar (SAR) based on compressive sensing (CS) is investigated in this paper. Conventional SAR has accomplished high resolution imaging on two-dimensional (2D) azimuth-range plane. Using the array structure in cross-track direction, the height resolution can be obtained and 3D imaging is achieved. Conventional imaging approach and imaging based on compressive sensing are used for imaging processing. The performance of both methods is analyzed. Numerical experiments have been made and simulation results are presented in this paper.