An electronic-scanning antenna composed of radiating elements each forming an active channel in which the signals arising from the channels are grouped together to form deviometry signals, each deviometry signal forming a deviometry channel, and are grouped together according to sectors to form a sector-based signal forming a sector channel, a computation-based beam being formed on the basis of the signals arising from each of the sectors, the method comprises the following steps: measuring the response to a calibration signal of each active channel at one and the same time on the sum deviometry channel and on the sector channel to which it belongs, the responses on the sum channel to obtain the calibration of the sum channel; computing, for each active channel, the disparity between the mean of the responses measured on the sum channel and the mean of the responses measured on the sector to which it belongs; in the operational phase, forming the beam by computation on the basis of the measurements of the signals arising from the sector channels calibrated with the calibration obtained for the sum channel, and correcting the computation of the beam as a function of the disparity.