Abstract
In this paper, a fast back-projection (BP) synthetic aperture radar (SAR) imaging algorithm based on wavenumber spectrum fusion is proposed for high maneuvering platforms with high squint angles and high dive angles. When the platforms have nonlinear trajectory errors, the trajectory errors will introduce significant spectrum displacement, which varies with the target position. If the influence of trajectory error is not considered, the trajectory’s deviation from the ideal SAR imaging geometry will degrade the focusing performance. The dive angle will further enlarge the influence on SAR focusing. In this paper, the center function of the spatially variable sub-aperture wavenumber spectrum is derived, firstly, which is the basis for reasonably setting the oversampling rate. Then, the accurate spectrum fusion method is proposed, which is efficiently implemented by fast Fourier transform (FFT) and circular shifting. The proposed algorithm is called high-squint and high-dive accelerated factorized back-projection (HSHD-AFBP). Compared to the commonly used spectrum fusion method, HSHD-AFBP not only improves the imaging quality, but also expands the image width. Finally, the effectiveness of the proposed algorithm is verified by simulation data.
Highlights
HSHD-AFBPmethod methodwas wasproposed proposedfor forhigh highsquint squintangle angleand andhigh high dive angle imaging, which is suitable for the nonlinear motion trajectory
The method was proposed for high squint angle and dive angle synthetic aperture radar (SAR) imaging, which is suitable for the nonlinear motion trajectoryofofhigh high maneuvering platforms
SAR imaging, which is suitable for the nonlinear motion trajectory of maneuvering platforms
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The high-squint AFBP algorithm (HS-AFBP) for airborne SAR processing is proposed in [19], and two spectrum center functions are given for linear and nonlinear trajectories. Based on the high maneuvering platforms SAR imaging geometry, the relationship of the sub-aperture wavenumber spectrum centroid position and the target position is firstly derived. It is found that the center position of the sub-aperture wavenumber spectrum varies with the target position if the nonlinear motion errors occur for the high maneuvering platforms. The proposed spectrum fusion method can overcome the spatial variation influence of the center position of the sub-aperture spectrum, and the SAR focusing performance can be guaranteed effectively.
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