Fast Factorized Backprojection Algorithm in Orthogonal Elliptical Coordinate System for Ocean Scenes Imaging Using Geosynchronous Spaceborne–Airborne VHF UWB Bistatic SAR

Geosynchronous (GEO) spaceborne–airborne very high-frequency ultra-wideband bistatic synthetic aperture radar (VHF UWB BiSAR) can conduct high-resolution and wide-swath imaging for ocean scenes. However, GEO VHF BiSAR faces some challenges such as the geometric configuration, huge amount of echo data, serious range–azimuth coupling, large spatial variance, complex motion error, which increases difficulty high-efficiency high-precision imaging. In this paper, we present an improved fast factorization backprojection (FFBP) algorithm scene using satellite-unmanned aerial vehicle (GEO-UAV) BiSAR, solve above issues with high efficiency precision. This method reconstructs subimages in orthogonal elliptical polar (OEP) coordinate system based on satellite UAV trajectories well location imaged scene, further reduce computational burden. First, geometry signal model GEO-UAV are established, construction OEP subaperture proposed. Moreover, Nyquist sampling requirements derived from range error perspective, offer a near-optimum tradeoff between precision efficiency. addition, superiority is analyzed, demonstrates that angular dimensional rate significantly reduced. Finally, implementation processes burden proposed provided, speed-up factor FFBP compared BP discussed. Experimental results ideal point targets natural scenes demonstrate correctness effectiveness algorithm, achieve near-optimal performance low