  We present transport measurements on a bilayer graphene sheet with
homogeneous back gate and split top gate. The electronic transport data
indicates the capability to direct electron flow through graphene
nanostructures purely defined by electrostatic gating. By comparing the
transconductance data recorded for different top gate geometries - continuous
barrier and split-gate - the observed transport features for the split-gate can
be attributed to interference effects inside the narrow opening.
