Linear polarization measurements of extragalactic radio sources at lambda 6.3 cm

We present linear polarization measurements of 154 extragalactic radio sour ces at lambda 6.3 cm, as part of a continuing effort to expand and improve our Faraday rotation determinations of radio galaxies and quasars. The exce llent telescope optics of the Effelsberg 100 m telescope at this wavelength , combined with a matrix method we applied for calibrating out all componen ts of the instrumental polarization enables us to achieve better than avera ge accuracy in the determinations of linear polarization degree and positio n angle. In the absence of thermal noise errors, these are repeatable to be tter than 0.2% and 0.degrees 1 respectively, for the prime calibrator, 3C 2 86. A very brief overview of the results is also included.