Flux density measurements of a complete sample of faint blazars
  We performed observations with the Effelsberg 100-m radio telescope to
measure flux densities and polarised emission of sources selected from the
"Deep X-ray Radio Blazar Survey" (DXRBS) to better define their spectral index
behaviour in the radio band, with the aim to construct a homogeneous sample of
blazars. Sources were observed at four different frequencies with the
Effelsberg 100-m telescope. We complemented these measurements with flux
density data at 1.4GHz derived from the NRAO VLA Sky Survey.The spectral
indices of a sample of faint blazars were computed making use of almost
simultaneous measurements. Sixty-six percent of the sources can be classified
as "bona fide" blazars. Seven objects show a clearly inverted spectral index.
Seventeen sources previously classified as flat spectrum radio quasars (FSRQs)
are actually steep spectrum radio quasars (SSRQs). The flux densities obtained
with the Effelsberg 100-m telescope at 5GHz are compared with the flux
densities listed in the Green Bank GB6 survey and in the Parkes-MIT-NRAO PMN
catalogue. About 43% of the sources in our sample exhibit flux density
variations on temporal scales of 19 or 22 years. We confirm that 75 out of 103
sources of the DXRBS are indeed FSRQs. Twenty-seven sources show a spectral
index steeper than -0.5 and should be classified as SSRQs. Polarised emission
was detected for 36 sources at 4.85GHz. The median value of the percentage of
polarised emission is (5.8+-0.9$)%. Five sources show rotation measure (RM)
values >200 rad m^-2.
