  High-frequency observations of the tailed radio galaxies IC 310, NGC 1265, 3C
129, and 3C 465 have been performed with the Effelsberg 100-m telescope. For
the radio galaxies IC 310, NGC 1265 and 3C 465, radio data obtained at low
frequencies with the Westerbork Synthesis Radio Telescope are also available.
These new radio data allow us to map the extended structure of the radio
galaxies and obtain spectral and polarization information in the outermost
regions. The multi-frequency spectra were used to study the synchrotron ageing
of relativistic electrons with increasing distance from the active nucleus. We
found that the spectrum in each radio galaxy progressively steepens with
distance, and at each location it is steeper at high frequencies. The spectra
are fitted by models involving synchrotron energy losses and the critical
frequency is obtained at increasing distance from the core. Assuming that the
magnetic field is the equipartition value, we obtain the radiating electron
lifetimes and consequently their drift velocities. Our results imply the
existence of reacceleration processes or bulk motions along the tails. The
polarization data at 10.6 GHz give information on the intrinsic degree of
polarized flux and the orientation of the magnetic field. We find that the
polarization percentage increases along the tails, reflecting an increase of
the degree of ordering of the magnetic field. The magnetic field in the tails
is longitudinal.
