  Advances in graphene plasmonics offer numerous opportunities for enabling the
design and manufacture of a variety of nanoelectronics and other exciting
optical devices. However, due to the limitation of material properties, its
operating frequency cannot drop to the microwave range. In this work, a new
concept of microwave equivalent graphene based on the ultrathin monolayer
plasmonic metasurface is proposed and demonstrated. Based on this concept,
elliptical and hyperbolic dispersion can be theoretically obtained by stacking
the equivalent graphene metasurfaces periodically. As proofs of the concept and
method, an elliptical and an all-metal hyperbolic metamaterial are designed and
numerically demonstrated. As a specified realization of the method, a practical
hyperbolic metamaterial is fabricated and experimentally investigated with its
validity verified by the directional propagation and photonic spin Hall effect.
Furthermore, to investigate the validity of the method under extreme parameter
conditions, a proof-of-concept hyperlens is designed and fabricated, with its
near-field resolution of 0.05$\lambda$ experimentally verified. Based on the
proposed concept, diverse optical graphene metamaterials such as focusing lens,
dispersion-dependent directional couplers, and epsilon-near-zero materials can
also be realized in the microwave regime.
