  An analytical circuit model able to predict the input impedance of
reconfigurable graphene plasmonic dipoles is presented. A suitable definition
of plasmonic characteristic impedance, employing natural currents, is used to
for consistent modeling of the antenna-load connection in the circuit. In its
purely analytical form, the model shows good agreement with full-wave
simulations, and explains the remarkable tuning properties of graphene
antennas. Furthermore, using a single full-wave simulation and scaling laws,
additional parasitic elements can be determined for a vast parametric space,
leading to very accurate modeling. Finally, we also show that the modeling
approach allows fair estimation of radiation efficiency as well. The approach
also applies to thin plasmonic antennas realized using noble metals or
semiconductors.
