Forward-looking bistatic SAR imaging based on high-order range equation and high-order phase compensation

摘要

Synthetic aperture radar (SAR) techniques are typically used to achieve a high azimuth resolution, but conventional monostatic SAR is not applicable in forward direction because of azimuth ambiguities and poor Doppler resolution. This paper focuses on SAR imaging processing in a novel forward-looking bistatic configuration that a pilotless plane transmits signals and a guided missile receives echo which can avoid image ambiguities and to improve the azimuth resolution. A fourth-order range equation and a fourth-order phase term are adopted to improve the accuracy in the approximation of the range history and two-dimensional spectrum for forward-looking bistatic SAR, respectively. The spectrum is used for high-order phase compensation, range compression, secondary range compression, range cell migration correction, and azimuth compression. Especially, the proposed algorithm is able to focus the translational variant bistatic configuration where the transmitter and receiver platforms are moving in parallel tracks with different velocities and high squints. Finally, simulations validate the effectiveness of the algorithm.