  We report on sensitive 21cm and 11cm polarization surveys of the Galactic
plane carried out with the Effelsberg 100-m telescope at arcmin angular
resolution and some related work. Highly structured polarized emission is seen
along the Galactic plane as well as up to very high Galactic latitudes. These
observations reflect Faraday effects in the interstellar medium. Polarized
foreground and background components along the line of sight, modified by
Faraday rotation and depolarization, add in a complex way. The amplitudes of
polarized emission features are highly frequency dependent. Small-scale
components decrease in amplitude rapidly with increasing frequency. We stress
the need for sensitive absolutely calibrated polarization data. These are
essential for baseline setting and a correct interpretation of small-scale
structures. Absolutely calibrated data are also needed to estimate the
high-frequency polarized background. A recent study of polarized emission
observed across the local Taurus-Auriga molecular cloud complexes indicates
excessive synchrotron emission within a few hundred parsecs. These results
suggest that possibly a large fraction of the Galactic high latitude total
intensity and polarized emission is of local origin.
