In the context of ground surveillance, moving targets detection and localization are key issues. Recently, SAR/GMTI algorithms involving several antennas have been proposed. However, the antennas may have different antenna patterns, and they point to a direction with slightly different angles. These difference evolve dissimilarly as the aircraft moves along the azimuth direction, causing a loss of coherence between the obtained images. This loss of coherence causes a loss in detection capacities. In this paper, we propose a method of recalibrating the antennas with respect to one another. This method does not require any a priori knowledge on the antennas, and enables an improvement of the detection capacities.