For slow target detection with airborne array radars, the ground clutter Doppler spreading due to the platform movement is a limiting factor, especially for long wavelength radars. In this paper, it will be shown that two procedures for slow target detection (Doppler-angle imaging or space-time processing, and movement compensation) are equivalent [2], [3], and that an original real-time procedure for antenna array calibration using clutter returns can be combined with these detection techniques to increase subclutter visibility in presence of high clutter returns.