Abstract
For a three-dimensional wide-angle synthetic aperture radar (SAR) with non-uniform sampling, it is necessary to divide its large aperture into several small sub-apertures before imaging due to the anisotropic characteristics of the target. The existing sub-aperture partitioning methods divide the aperture with equal intervals. However, for the non-uniformly sampled SAR, those equal-interval partitioning methods may have a bad effect on the resolution of the SAR imaging result. In view of this, a sub-aperture partitioning method for three-dimensional wide-angle SAR imaging with non-uniform sampling was proposed in this paper. First, we analyzed the relationship between the three-dimensional resolution and the sampling distribution in K-space based on the Cramer–Rao lower bound. Subsequently, according to the distribution of K-space sampling, the optimum size of each sub-aperture was found and the aperture was divided non-uniformly. Furthermore, the proposed method was validated by electromagnetic simulation data. The proposed sub-aperture partitioning method ensured that the resolution of each sub-aperture was high and consistent. By comparing with the equal-interval partitioning method, the experimental results showed that our proposed method had a higher resolution imaging result.
Highlights
Synthetic aperture radar (SAR) is an active microwave imaging sensor, which has the advantage of all-day and all-weather observation
Modelthat the assumption of isotropic scattering is invalid for the 3-D wide-angle SAR with
The correctness of the 3-D resolution estimation VCRLB was verified by the following experiment: A reflector with limited persistence of 30◦ was placed in the center of the scene
Summary
Synthetic aperture radar (SAR) is an active microwave imaging sensor, which has the advantage of all-day and all-weather observation. In recent years, acquiring more comprehensive information from the target has become the development trend of SAR [1,2,3]. Uniform and dense sampling of Tomo-SAR makes data collection time-consuming and high-cost [9,10]. 3-D wide-angle SAR data can be obtained through the non-linear flight of SAR, which reduces the cost of data acquisition greatly [11,12,13]. On this basis, Electronics 2019, 8, 629; doi:10.3390/electronics8060629 www.mdpi.com/journal/electronics
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