FRB Model: Physical picture of an X-mode EM wave traveling through a neutron star magnetosphere. The magnetic field configuration near the source region, which is near the surface, is complex. As the wave travels outwards, the electric vector adiabatically rotates in such a way that it is always perpendicular to the local magnetic field. At large distances from the neutron star (but still well below the light cylinder), where the plasma density becomes too small to force the electric vector to follow the changing direction of the magnetic field, the polarization angle is frozen. At this freeze-out radius (not shown in this picture since it is >>Rns), the magnetic field is nearly dipolar and the wave vector is nearly in the radial direction from the center of the star, so the electric vector of the escaping wave is perpendicular to the magnetic dipole moment of the neutron star."