Near-Field FMCW SAR Imaging With Fast BPA

Conventional imaging algorithms, such as the Back Projection Algorithm (BPA) and the Range Migration Algorithm (RMA), have their own respective limitations in terms of computational complexity and efficiency. While BPA delivers high-resolution imaging, it demands significant computational resources. In contrast, RMA is more computationally efficient but sacrifices some precision. To address these challenges, a new near-field imaging algorithm called FastBPA is introduced. It builds on BPA and leverages the Fast Fourier Transform (FFT) for faster imaging, similar to RMA. A comparison of the computational complexities of RMA, BPA, and FastBPA shows that FastBPA reduces the time complexity of BPA imaging from Ο (N<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>L<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>) to Ο (NLlog(NL)), making it equivalent to that of RMA. Experimental results from the 3DRIED dataset demonstrate that FastBPA matches BPA in focusing accuracy.