An outphasing calibration method in an outphasing calibration RF transmitter comprises detection of differences of a first plurality of signal characteristics of a first plurality of amplified RF signals across at least a transmitter antenna and a plurality of load impedances. The first plurality of amplified RF signals corresponds to a first plurality of constant-envelope signals. Accordingly, at least a generation of a second plurality of constant-envelope signals and at least one signal characteristic of each of a second plurality of constant-envelope RF signals on a plurality of transmission paths are controlled. At least one of a first calibration or a second calibration of a second plurality of signal characteristics of the second plurality of constant-envelope signals is executed based on the controlled generation of the second plurality of constant-envelope signals and the at least one controlled signal characteristic of each of the second plurality of constant-envelope RF signals.