Method of calibrating a transmitting antenna or transmitter, or a receiving antenna or receiver, of a polarimetric radar, the antenna to be calibrated and a viewed scene used for the method having polarimetric characteristics which remain substantially constant during the measuring step of the method, said method comprising: 1) a measuring step, comprising at least three polarimetric measurements (ST0, ST2, ST4; ST0, ST7, ST9), each measurement comprising an emission of an electromagnetic signal by the transmitter in, in succession, at least two first polarisations which form a base for transmission polarisation, and comprising, for each first polarisation, a detection by the receiver of part of the signal reflected by the viewed scene, in at least two second polarisations which form a base for reception polarisation, and 2) a step of estimating polarimetric characteristics of the antenna to be calibrated (ST5; ST10) from results of said polarimetric measurements, said method being characterized in that, in the measuring step 1): - at least two (ST2, ST4; ST7, ST9) of said at least three polarimetric measurements are performed with a detachable means, said detachable means having two active axes (B1, B2), being arranged on a path of the signal between the antenna to be calibrated and the viewed scene, and differently attenuating and/or delaying two components of the polarisation of the signal which are parallel to respective ones of the two active axes, - an angular position of the two active axes (B1, B2) about a direction of propagation of the signal at the location of the detachable means is varied between each of said at least two polarimetric measurements (ST2, ST4; ST7, ST9), and - at least one other of said at least three polarimetric measurements is performed without the detachable means, and in that the estimating step 2) comprises a solving of a system of equations which at least partly characterize polarimetric distortions caused by the transmitter or receiver and which are modelled by matrices of complex numbers. 1) a measuring step, comprising at least three polarimetric measurements (ST0, ST2, ST4; ST0, ST7, ST9), each measurement comprising an emission of an electromagnetic signal by the transmitter in, in succession, at least two first polarisations which form a base for transmission polarisation, and comprising, for each first polarisation, a detection by the receiver of part of the signal reflected by the viewed scene, in at least two second polarisations which form a base for reception polarisation, and 2) a step of estimating polarimetric characteristics of the antenna to be calibrated (ST5; ST10) from results of said polarimetric measurements, - at least two (ST2, ST4; ST7, ST9) of said at least three polarimetric measurements are performed with a detachable means, said detachable means having two active axes (B1, B2), being arranged on a path of the signal between the antenna to be calibrated and the viewed scene, and differently attenuating and/or delaying two components of the polarisation of the signal which are parallel to respective ones of the two active axes, - an angular position of the two active axes (B1, B2) about a direction of propagation of the signal at the location of the detachable means is varied between each of said at least two polarimetric measurements (ST2, ST4; ST7, ST9), and - at least one other of said at least three polarimetric measurements is performed without the detachable means,