  We analytically and numerically study the nonreciprocal surface waves guided
by a magnetized metasurface tube. When applying the magnetic bias
perpendicularly to the cylinder axis, the conductivity profile cross-section is
nonuniform, which enables us to obtain pronounced nonreciprocal modes with
different field distributions for propagation in opposite directions due to the
coupling between different values of orbital angular momentum. We show that
this property can be leveraged for directional power delivery when changing the
source location, and we study the isolation ratio as a function of different
parameters. The simple, continuous dependence of the isolation on the direction
of magnetization allows simple yet robust control over the wave propagation
properties.
