  The latest results of the most detailed analysis of multi-epoch
polarization-sensitive observations of active galactic nuclei (AGN) jets at
parsecs scales by very long baseline interferometry (VLBI) reveal several
characteristic patterns of linear polarization distribution and its variability
(Pushkarev et al., 2023; Zobnina et al., 2023). Some of the observed profiles
can be reproduced by a simple model of a jet threaded by a helical magnetic
field. However, none of the models presented to date can explain the observed
polarization profiles with an increase in its degree towards the edges of the
jet, and accompanied by a 'fountain' type electric vector pattern and its high
temporal variability in the center. Based on simulations of the VLBI
observations of relativistic jets, we show here that the observed transverse
linear polarization profiles, atypical for the simple magnetic field models can
be naturally produced assuming the finite resolution of VLBI arrays and
precession of a jet on ten-years scales, observational indications of which are
found in an increasing number of AGN. In our simulations, we qualitatively
reproduce the distribution of the electric vector and its variability, though
the polarization images are characterized by a bright spine due to weak
smearing, which is poorly consistent with observations. More effective
depolarization can be obtained in models with the suppressed emission of the
jet spine.
