  We have developed a model for pulsar polarization by taking into account of
viewing geometry, rotation and modulation of the emission region. By solving
for the plasma dynamics, we deduced the expressions for curvature radiation
electric field in time as well as frequency domains. We show that both the
'antisymmetric' and 'symmetric' types of circular polarization are possible due
to the combined effect of aberration, viewing geometry and modulation. We argue
that aberration combined with modulation can introduce 'kinky' pattern into the
PPA traverses.
