  The paper deals with the one possible mechanism of the pulsar radio emission,
i.e., with the collective curvature radiation of the relativistic particle
stream moving along the curved magnetospheric magnetic field lines. It is shown
that the electromagnetic wave containing one cylindrical harmonic exp{is{\phi}}
can not be radiated by the curvature radiation mechanism, that corresponds to
radiation of a charged particle moving along curved magnetic field lines. The
point is that the particle in vacuum radiates the triplex of harmonics (s, s
\pm 1), so for the collective curvature radiation the wave polarization is very
important and cannot be fixed a priori. For this reason the polarization of
real unstable waves must be determined directly from the solution of wave
equations for the media. Its electromagnetic properties should be described by
the dielectric permittivity tensor \^{\epsilon}({\omega},k,r), that contains
the information on the reaction on all possible types of radiation.
