  The lowest six rotational bands have been studied in the particle-rotor model
with the particle-hole configuration $\pi h^1_{11/2}\otimes\nu h^{-1}_{11/2}$
and different triaxiality parameter $\gamma$. Both constant and spin-dependent
variable moments of inertial (CMI and VMI) are introduced. The energy spectra,
electromagnetic transition probabilities, angular momentum components and
$K$-distribution have been examined. It is shown that, besides the band 1 and
band 2, the predicted band 3 and band 4 in the calculations of both CMI and VMI
for atomic nuclei with $\gamma=30^\circ$ could be interpreted as chiral doublet
bands.
