Conveniently, the value of the inductors L_AK or L_GK may be varied during calibration to adjust the value of the voltage V_PAR according to the voltage V_RF provided to the applicator 2. Particularly, the voltage V_PAR may be a predetermined fixed portion of the voltage V_RF presented to the applicator 2.

Conveniently, the voltage V_PAR may range from 10% to 20% the value of the voltage V_RF and is preferably about 15% the value of the voltage V_RF.

The variable resistance circuit 22 may be connected downstream from the divider circuit 21 and may be electrically connected to the second terminal 25 of the inductor L_B and the cathode K of the triode 19.

FIGS. 3 to 7 schematically show three different types of variable resistance circuits 22.

Particularly, in the embodiment of FIGS. 3 and 4, the variable resistance circuit 22 may be electrically equivalent to a variable resistor R.

Alternatively, as shown in FIG. 5, the variable resistance circuit 22 may be electrically equivalent to a DC voltage generator, with a variable electrically potential tension E.

Conveniently, the central control unit 23 may be programmed to control the ohmic value R of the equivalent variable resistor or the value of the electrically potential tension E of the equivalent generator according to the instantaneous value of the voltage V_RF provided to the applicator 2.