We have presented new polarization data at 6 cm for a sample of 62 B2 radio galaxies. We have measured integrated m and mean m' polarization parameters and compared them with the old data obtained for the same sample at 20 cm. We find the following results:
a) the lobe median value of m' for double sources is 
, larger
than the corresponding median value found at 20 cm. This implies
depolarization between the two wavelengths;
b) the distribution of depolarization ratios is consistent with the halo depolarization model presented by Garrington & Conway (1991);
c) After correcting for Faraday rotation, the magnetic fields in the lobes show preferentially a circumferential geometry. In the jets the field is mostly perpendicular to the source axis, although with a few noticeable exceptions.
Acknowledgements
The National Radio Astronomy Observatory is operated by Associated Universities, Inc., under contract with National Science Foundation.