  Artificial graphene consisting of honeycomb lattices other than the atomic
layer of carbon has been shown to exhibit electronic properties similar to real
graphene. Here, we reverse the argument to show that transport properties of
real graphene can be captured by simulations using "theoretical artificial
graphene." To prove this, we first derive a simple condition, along with its
restrictions, to achieve band structure invariance for a scalable graphene
lattice. We then present transport measurements for an ultraclean suspended
single-layer graphene pn junction device, where ballistic transport features
from complex Fabry-P\'erot interference (at zero magnetic field) to the quantum
Hall effect (at unusually low field) are observed and are well reproduced by
transport simulations based on properly scaled single-particle tight-binding
models. Our findings indicate that transport simulations for graphene can be
efficiently performed with a strongly reduced number of atomic sites, allowing
for reliable predictions for electric properties of complex graphene devices.
We demonstrate the capability of the model by applying it to predict so-far
unexplored gate-defined conductance quantization in single-layer graphene.
