1995A&A...299..671D

Polarization sensitive VLBI images at 5GHz are presented for the Compact Steep-Spectrum radio quasar 3C 138. The polarized emission is dominated by the main jet, ≃1kpc in length; the core instead is weakly polarized, if at all, at this frequency. The magnetic field geometry on scales of 10 mas is mostly longitudinal, with evidence of sub-structures at the end of the jet, where the interaction with the ambient medium is most pronounced; the orientation of the ordered component of the magnetic field becomes roughly tangential at the end of the jet. The overall polarization features seem to be similar both to the pc-scale radio jets of flat spectrum, core dominated quasars, and to the kpc-scale jets seen in extended, lobe dominated powerful FRII radio sources.