An Imaging Method for Arc Array Bistatic SAR With an Accelerated Moving Transmitter

Abstract

In arc array bistatic synthetic aperture radar (AA-BiSAR), an accelerated moving transmitter is helpful for enlarging the imaged scene and improving the flexibility of the imaging system, which is of great significance in the field of helicopter assisted landing and emergency rescue. The motion state of the transmitter is closely related to the SAR echo model and the imaging quality. In this paper, the imaging geometry of AA-BiSAR with an accelerated moving transmitter is established, and the impact of the transmitter acceleration on the imaging quality is analyzed. According to the echo signal model, a twostep compensation imaging algorithm based on the series reversion method is proposed. First, the first compensation for the residual phase caused by the movement of the transmitter is operated in the azimuth-time range-frequency domain by the transfer function, which is obtained from the approximated fourth-order high-precision Taylor series expansion of the double-root bistatic slant range. Then, the second compensation for the coupling terms between angle and range frequencies are carried out in the two-dimensional (2D) frequency domain by uniform range migration and second range compression functions. The 2D spectrum is derived by the series inversion method. Imaging results of simulated point and distributed targets are validated the proposed imaging method.