  Recently there has been reinvigorated interest in the superconducting
proximity effect, driven by predictions of the emergence of Majorana fermions.
To help guide this search, we have developed a phenomenological model for the
tunneling spectra in anisotropic superconductor-normal metal proximity devices.
We combine successful approaches used in s-wave proximity and standard d-wave
tunneling to reproduce tunneling spectra in d-wave proximity devices, and
clarify the origin of various features. Different variations of the pair
potential are considered, resulting from the proximity-induced
superconductivity. Furthermore, the effective pair potential felt by the
quasiparticles is momentum-dependent in contrast to s-wave superconductors. The
probabilities of reflection and transmission are calculated by solving the
Bogoliubov equations. Our results are consistent with experimental observations
of the unconventional proximity effect and provide important experimental
parameters such as the size and length scale of the proximity induced gap, as
well as the conditions needed to observe the reduced and full superconducting
gaps.
