A method of calibrating a multiport amplifier comprising a plurality of input ports, a plurality of power amplifiers linked to input ports by a matrix distributing signals, a plurality of output ports linked to the power amplifiers by a matrix recombining signals and a plurality of elements for weighting the signals associated with the power amplifiers, comprises: determining a normalized mean cross-correlation between an output signal present at the output port, taken as reference, and the signals present at the other output ports; and iteratively adjusting weights of the weighting elements so as to minimize the normalized mean cross-correlation or to render it less than a predetermined threshold. A multiport amplifier comprising a calibration module configured or programmed to implement such a calibration method, and a satellite for telecommunications whose payload comprises such a multiport amplifier, are also provided.