  D-H type II radio bursts are widely thought to be caused by the coronal mass
ejections (CMEs). However, it is still unclear where the exact source of the
type IIs on the shock surface is. We identify the source regions of the
decameter-hectometric (D--H) type IIs based on imaging observations from
SOHO/LASCO and the radio dynamic spectrum from Wind/Waves. The analysis of two
well-observed events suggests that the sources of these two events are located
in the interaction regions between shocks and streamers, and that the shocks
are enhanced significantly in these regions.
