A Bidirectional Resampling Imaging Algorithm for High Maneuvering Bistatic Forward-Looking SAR Based on Chebyshev Orthogonal Decomposition

High maneuvering bistatic forward-looking SAR (HMBFSAR) has the characteristics of time-delay large migration, Doppler large bandwidth, and parameter strong space variation, which pose challenges to its imaging. Focus on this problem, an imaging algorithm based on bidirectional resampling for HMBFSAR is presented. First, the slant range equation established by Chebyshev orthogonal decomposition and the non-stop-and-go echo model based on the range equation are put forward. Second, an operate of range resampling is performed on the echo in the 2-D frequency domain, which reduces the effect caused by range cell migration (RCM). Finally, the azimuth frequency resampling operate is introduced in the range-Doppler (RD) domain to achieve precise focusing. Simulation results show that the proposed non-stop-and-go echo model and the slant range equation based on Chebyshev orthogonal decomposition have high accuracy, and the bidirectional resampling algorithm effectively solves the space-variant problem caused by high speed and acceleration in HMBFSAR, thereby improving the imaging performance of edge point targets.

I. Introduction

High maneuvering platform bistatic forward-looking SAR is a new special imaging mode that can be applied to various weather conditions [1], [2], [3], [4]. In this configuration, the transmitter transmits pulse signals to the target scene in side-looking mode, and the receiver works in forward looking or high squint to receive echo signals reflected from the target area to achieve forward-looking imaging of the targets, which breaks through the limitation of forward-looking limited vision area of monostatic SAR. It has important application value in military and civil fields, such as precision guidance and autonomous navigation landing of aerospace vehicles [5], [6], [7]. However, there are few frequency-domain imaging algorithms for bistatic forward-looking SAR with high maneuvering platform.