Linear polarization measurements of extragalactic radio sources at

We present linear polarization measurements of 154 extragalactic radio sources at $\lambda6.3$ cm, as part of a continuing effort to expand and improve our Faraday rotation determinations of radio galaxies and quasars. The excellent telescope optics of the Effelsberg 100 m telescope at this wavelength, combined with a matrix method we applied for calibrating out all components of the instrumental polarization enables us to achieve better than average accuracy in the determinations of linear polarization degree and position angle. In the absence of thermal noise errors, these are repeatable to better than 0.2% and $0\hbox{$.\!\!^{\circ}$} 1$ respectively, for the prime calibrator, 3C 286. A very brief overview of the results is also included