  A linear theory of a wakefield excitation in a plasma-dielectric accelerating
structure by a drive electron bunch in the case of an off-axis bunch injection
has been constructed. The structure under investigation is a round
dielectric-loaded metal waveguide with a channel for the charged particles,
filled with homogeneous cold plasma. Derived theory was used to investigate
numerically the spatial distribution of the bunch-excited wakefield components,
which act on both the drive and witness bunches.
