Magnetic fields in quasar 3C147 on milliarcsecond scales

VLBA polarimetric observations of the steep-spectrum quasar 3C147 were made at four frequencies in the available 5 GHz band, from which polarization i n one bright feature in the inner jet was detected. The rotation measure of this feature (similar to 1300 rad m(-2)) agrees with the known high rotati on measure of the source, which makes it possible to remove the Faraday scr een pixel-by-pixel and obtain the intrinsic magnetic field structure. The a rch shape of B vectors suggests that a relativistic and distorted jet is be ing seen in projection.