Micro-Doppler effect for airborne downward-looking array SAR imaging

Imaging defocusing may occur due to phase error induced by vibration of conformal antenna array fixed on wings of airborne array synthetic aperture radar(SAR).Micro-Doppler effect of airborne downward-looking array frequency modulated continuous wave(FMCW)SAR imaging is studied based on micro-Doppler model and time-frequency analysis method.Vibration model is established combined with array antenna vibration geometry model, and signal characteristic is analyzed.Then,imaging simulation and analysis of micro-Doppler effect are carried out based on time-frequency analysis method.Results indicate that the proposed method can realize accurate estimation of the antenna array vibration error.