  We study the ballistic magnetotransport in a double quantum point contact
(QPC) device consisting of a quasi-one-dimensional quantum wire with an
embedded island-like impurity - etched nano-hole as in a recently published
experiment [J. C. Chen, Y. Lin, K.-T. Lin, T. Ueda and S. Komiyama, Appl. Phys.
Lett. 94, 012105 (2009)]. We reproduce the zero field quantized conductance,
the interference phenomenon induced by the coupled QPCs, as well as the
Ramsauer-like resonances observed in the experiments. At finite magnetic fields
Fano-type resonances arises in the conductance due to the formation of
localized states at the impurity periphery and to an inter-edge state resonant
coupling effect. It is predicted that the Fano-type resonances can be
controlled by an asymmetric confinement of the QPCs.
