Double-base SAR (Synthetic Aperture Radar) synchronization-free echo focus imaging method based on direct wave

The invention provides a double-base SAR (Synthetic Aperture Radar) synchronization-free echo focus imaging method based on a direct wave. The method is characterized by comprising the following steps of: setting M squint angles theta and N Doppler center frequencies fdc; selecting one squint angle and the N Doppler center frequencies fdc to form N secondary matched filters to carry out secondary distance compression on target echoes so as to obtain an optimal Doppler center frequency fdc_best; forming M secondary matched filters by the optimal Doppler center frequency fdc_best and the M squint angles theta to carry out the secondary distance compression on the target echoes to obtain an optimal squint angle theta_best; utilizing to forming an optimal secondary matched filter by utilizing the optimal Doppler center frequency fdc_best and the optimalsquint angle theta_best to realize the secondary distance compression on the target echoes; and carrying out further treatment on the compressed target echoes to obtain an SAR ground distance image. According to the method disclosed by the invention, under the conditions of time synchronization and phase synchronization of releasing complexity of echo data, a target image is rapidly obtained.