  The line widths of broad line regions (BLRs) of AGNs are key parameters for
understanding the central super massive black holes (SMBHs). However, due to
obscuration from dusty torus, optical recombination lines from BLRs in type II
AGNs can not be directly detected. Radio recombination lines (RRLs), with low
extinction, can be ideal tracers to probe emission from BLRs in type II AGNs.
We performed RRL observations for H35$\alpha$ and H36$\alpha$ toward the center
of Circinus galaxy with ALMA. Narrow components of H35$\alpha$ and H36$\alpha$,
which are thought to be mainly from star forming regions around the nuclear
region, are detected. However, only upper limits are obtained for broad
H35$\alpha$ and H36$\alpha$. Since Circinus galaxy is one of the nearest AGN,
non-detection of broad RRLs in Circinus galaxy at this band tells us that it is
hopeless to detect broad RRL emission in local AGNs with current facilities.
Submillimetre RRLs, with flux densities that are dozens of times higher than
those at the millimetre level, could be the tools to directly detect BLRs in
type II AGNs with ALMA, once its backend frequency coverage has been upgraded
to several times better than its current capabilities.
