[en] Measurements of electron density profile via microwave reflectometry using plasma probing by EM waves with ordinary (O) mode polarization are widely used for both tokamaks and stellarators. Extraordinary (X)-mode probing is less common because the refraction index of this wave depends on an additional parameter - magnetic field. In tokamaks the total magnetic field depends strongly on plasma current profile and is unknown a priori. It is not a case for stellarators where plasma influence on the total magnetic field distribution is weak (of order of beta). This allows to reconstruct the electron density profile from measurements of X-mode cut-off position versus probing frequency using data of the vacuum magnetic field calculation along the wave trajectory. 3 refs, 5 figs