  The polarization characteristics of zebra patterns (ZPs) in type IV solar
bursts were studied. We analyzed 21 ZP events observed by the Assembly of
Metric-band Aperture Telescope and Real-time Analysis System between 2010 and
2015 and identified the following characteristics: a degree of circular
polarization (DCP) in the range of 0%-70%, a temporal delay of 0-70 ms between
the two circularly polarized components (i.e., the right- and left-handed
components), and dominant ordinary-mode emission in about 81% of the events.
For most events, the relation between the dominant and delayed components could
be interpreted in the framework of fundamental plasma emission and
depolarization during propagation, though the values of DCP and delay were
distributed across wide ranges. Furthermore, it was found that the DCP and
delay were positively correlated (rank correlation coefficient R = 0.62). As a
possible interpretation of this relationship, we considered a model based on
depolarization due to reflections at sharp density boundaries assuming
fundamental plasma emission. The model calculations of depolarization including
multiple reflections and group delay during propagation in the inhomogeneous
corona showed that the DCP and delay decreased as the number of reflections
increased, which is consistent with the observational results. The dispersive
polarization characteristics could be explained by the different numbers of
reflections causing depolarization.
