  The Cassini mission crossed the source region of the Saturn kilometric
radiation (SKR) on 17 October 2008. On this occasion, the Radio and Plasma Wave
Science (RPWS) experiment detected both local and distant radio sources, while
plasma parameters were measured in situ by the magnetometer (MAG) and the
Cassini Plasma Spectrometer (CAPS). A goniopolarimetric inversion was applied
to RPWS 3-antenna electric measurements to determine the wave vector k and the
complete state of polarization of detected waves. We identify broadband
extraordinary (X) as well as narrowband ordinary (O) mode SKR at low
frequencies. Within the source region, SKR is emitted just above the X mode
cutoff frequency in a hot plasma, with a typical electron-to-wave energy
conversion efficiency of 1% (2% peak). The knowledge of the k-vector is then
used to derive the locus of SKR sources in the kronian magnetosphere, that
shows X and O components emanating from the same regions. We also compute the
associated beaming angle at the source theta'=(k,-B) either from (i) in situ
measurements or a model of the magnetic field vector or from (ii) polarization
measurements. Obtained results, similar for both modes, suggest
quasi-perpendicular emission for local sources, whereas the beaming pattern of
distant sources appears as a hollow cone with a frequency-dependent constant
aperture angle: theta'=75{\deg}+/-15{\deg} below 300kHz, decreasing at higher
frequencies to reach theta'(1000kHz)=50{\deg}+/-25{\deg}. Finally, we
investigate quantitatively the SKR polarization state, observed to be strongly
elliptical at the source, and quasi-purely circular for sources located beyond
approximately 2 kronian radii. We show that conditions of weak mode coupling
are achieved along the ray path, under which the magneto-ionic theory
satisfactorily describes the evolution of the observed polarization.
