Context : S147 is a large faint shell-type supernova remnant ( SNR ) known for its remarkable spectral break at cm-wavelength , which is an important physical property to characterize SNR evolution .
However , the spectral break is based on radio observations with limited precision .

Aims : New sensitive observations at high frequencies are required for a detailed study of the spectral properties and the magnetic field structure of S147 .

Methods : We conducted new radio continuum and polarization observations of S147 at \lambda 11 cm and at \lambda 6 cm with the Effelsberg 100-m telescope and the Urumqi 25-m telescope , respectively .
We combined these new data with published lower-frequency data from the Effelsberg 100-m telescope , and with very high-frequency data from WMAP to investigate the spectral turnover and polarization properties of S147 .

Results : S147 consists of numerous filaments embedded in diffuse emission .
We found that the integrated flux densities of S147 are 34.8 \pm 4.0 ~ { } Jy at \lambda 11 cm and 15.4 \pm 3.0 ~ { } Jy at \lambda 6 cm .
These new measurements confirm the known spectral turnover at \sim 1.5 GHz , which can be entirely attributed to the diffuse emission component .
The spectral index above the turnover is \alpha = -1.35 \pm 0.20 ~ { } ( S \sim \nu ^ { \alpha } ) .
The filamentary emission component has a constant spectral index over the entire wavelength range up to 40.7 GHz of \alpha = -0.35 \pm 0.15 .
The weak polarized emission of S147 is at the same level as the ambient diffuse Galactic polarization .
The rotation measure of the eastern filamentary shell is about -70 rad m ^ { -2 } .

Conclusions : The filamentary and diffuse emission components of S147 have different physical properties , which make S147 outstanding among shell type SNRs .
We attribute the weak polarization of S147 at \lambda 11 cm and at \lambda 6 cm to a section of the S147 shell showing a tangetial magnetic field direction .