  We study the influence of a tunnel barrier on the quantum transport through a
circular cavity. Our analysis in terms of classical trajectories shows that the
semiclassical approaches developed for ballistic transport can be adapted to
deal with the case where tunneling is present. Peaks in the Fourier transform
of the energy-dependent transmission and reflection spectra exhibit a
nonmonotonic behaviour as a function of the barrier height in the quantum
mechanical numerical calculations. Semiclassical analysis provides a simple
qualitative explanation of this behaviour, as well as a quantitative agreement
with the exact calculations. The experimental relevance of the classical
trajectories in mesoscopic and microwave systems is discussed.
