  Electron transport in a two-terminal Aharonov-Bohm ring with a few
short-range scatterers is investigated. An analytical expression for the
conductance as a function of the electron Fermi energy and magnetic flux is
obtained using the zero-range potential theory. The dependence of the
conductance on positions of scatterers is studied. We have found that the
conductance exhibits asymmetric Fano resonances at certain energies. The
dependence of the Fano resonances on magnetic field and positions of impurities
is investigated. It is found that collapse of the Fano resonances occurs and
discrete energy levels in the continuous spectrum appear at certain conditions.
An explicit form for the wave function corresponding to the discrete level is
obtained.
