  We present deep total intensity and polarization observations of the Coma
cluster at 1.4 and 6.6 GHz performed with the Sardinia Radio Telescope. By
combining the single-dish 1.4 GHz data with archival Very Large Array
observations we obtain new images of the central radio halo and of the
peripheral radio relic where we properly recover the brightness from the large
scale structures. At 6.6 GHz we detect both the relic and the central part of
the halo in total intensity and polarization. These are the highest frequency
images available to date for these radio sources in this galaxy cluster. In the
halo, we find a localized spot of polarized signal, with fractional
polarization of about 45%. The polarized emission possibly extends along the
north-east side of the diffuse emission. The relic is highly polarized, up to
55%, as usually found for these sources. We confirm the halo spectrum is
curved, in agreement with previous single-dish results. The spectral index is
alpha=1.48 +/- 0.07 at a reference frequency of 1 GHz and varies from alpha
~1.1, at 0.1 GHz, up to alpha ~ 1.8, at 10 GHz. We compare the Coma radio halo
surface brightness profile at 1.4 GHz (central brightness and e-folding radius)
with the same properties of the other halos, and we find that it has one of the
lowest emissivities observed so far. Reanalyzing the relic's spectrum in the
light of the new data, we obtain a refined radio Mach number of M=2.9 +/- 0.1.
