New SAR imaging algorithm via the optimal time-frequency transform domain

Computers, Materials and Continua (Tech Science Press)
Publication Type:
Journal Article
Computers, Materials and Continua, 2020, 65, (3), pp. 2351-2363
Issue Date:
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To address the low-resolution imaging problem in relation to traditional Range Doppler (RD) algorithm, this paper intends to propose a new algorithm based on Fractional Fourier Transform (FrFT), which proves highly advantageous in the acquisition of high-resolution Synthetic Aperture Radar (SAR) images. The expression of the optimal order of SAR range signals using FrFT is deduced in detail, and the corresponding expression of the azimuth signal is also given. Theoretical analysis shows that, the optimal order in range (azimuth) direction, which turns out to be very unique, depends on the known imaging parameters of SAR, therefore the engineering practicability of FrFT-RD algorithm can be greatly improved without the need of order iteration. The FrFT-RD algorithm is established after an analysis of the optimal time-frequency transform. Experimental results demonstrate that, compared with traditional RD algorithm, the main-lobe width of the peak-point target of FrFT-RD algorithm is narrow in both range and azimuth directions. While the peak amplitude of the first side-lobe is reduced significantly, those of other side-lobes also drop in various degrees. In this way, the imaging resolution of range and azimuth can be increased considerably.
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