Analysis and correction of the Doppler frequency shift of airborne forward looking array FMCW SAR

Combined with Frequency-Modulated Continuous-Wave (FMCW) technology, airborne forward-looking array synthetic aperture radar (SAR) can obtain the image in front of the aircraft and also have the advantages of FMCW radar such as small size and lightweight. Moreover, it is suitable to be installed on platforms like helicopter and small unmanned aerial vehicle. It´s valuable to study the imaging problem of airborne forward looking array SAR when aircraft platforms move toward the target areas in practice. This paper analyses the echo model based on geometry of forward looking array SAR and the Doppler frequency shift due to the movement of the aircraft platforms with a forward and downward velocity, studies a corresponding correction scheme and then presents an improved frequency scaling algorithm for forward looking array FMCW SAR. Finally, the algorithm is verified with the simulation and discussion.