  Electronic transport through a quantum wire sandwiched between two metallic
electrodes and coupled to a quantum ring, threaded by a magnetic flux $\phi$,
is studied. An analytic approach for the electron transport through the bridge
system is presented based on the tight-binding model. The transport properties
are discussed in three aspects: (a) presence of an external magnetic filed, (b)
strength of the wire to electrode coupling, and (c) presence of in-plane
electric field.
