  Magneto conductance oscillations periodic in flux with periodicity $\Phi_{0}$
and $\Phi_{0}/2$ are seen in asymmetric Aharonov-Bohm rings as a function of
density of electrons or Fermi wave vector. Dephasing of these oscillations is
incorporated using a simple approach of wave attenuation. In this work we study
how the excitation of the $\Phi_{0}/2$ oscillations and the accompanying phase
change of $\pi$ are affected by dephasing. Our results show that the
$\Phi_{0}/2$ oscillations survive incoherence, i.e., dephasing, albeit with
reduced visibility while incoherence is also unable to obliterate the phase
change of $\pi$.
