  Properties of circularly polarized waves are studied in the pulsar
magnetosphere plasma. It is shown that some observational characteristics of
the circular polarization observed in the pulsar radio emission can be
qualitatively explained in the framework of the model based on anomalous
Doppler resonance. Performed analysis provides that if the difference between
Lorentz factors of electrons and positrons is relatively high, one of the
circularly polarized waves becomes super-luminal and therefore can not be
generated by cyclotron instability. We suggest that this case corresponds to
the pulsars with the domination of one hand of circular polarization through
the whole averaged pulse profile at all observed frequencies. For intermediate
values of the difference between Lorentz factors both circularly polarized
waves are generated, but the waves of one handness are much more effectively
generated for high frequencies, whereas generation of another handness
dominates for low frequencies. This should correspond to the pulsars with
strong frequency dependence of the degree of circular polarization. The case of
relatively small difference between Lorentz factors corresponds to the pulsars
with sign reversal of the circular polarization in the centre of averaged pulse
profiles.
