  In this paper we investigate the polarization property of the radiation
amplified by astronomical masers in the presence of a strong magnetic field.
Our model explicitly takes into account the broadband nature of the radiation
field and the interaction of the radiation with the maser transition J=1--0.
The amplification of different realisations of the background continuum
radition by the maser is directly simulated and the Stokes parameters of the
radiation field are then obtained by averaging over the ensemble of emerging
maser radiation. For isotropic pumping and partially saturated masers we find
that the maser radiation is linearly polarized in two representative cases
where the magnetic field {\bf B} makes an angle $\theta$=30$^0$ and
$\theta$=90$^0$ to the maser axis. The linear polarization for maser radiation
obtained in our simulations for both cases are in agreement with the results of
the standard model. Furthermore, no instability during amplification is seen in
our simulations. Therefore, we conclude that there is no problem with the
previous numerical investigations of maser polarization in the unsaturated and
partially saturated regime.
