Dynamical THz Conductivity of Graphene for Ultrawide Band Antennas

Graphene is able to sustain electromagnetic wave propagation via plasmon formation and at GHz and THz frequencies and this opens up the possibility of graphene being employed for near field device-to-device communications. Here we show that at THz frequencies it is possible to adjust the inter- and intraband contributions to graphene’s dynamical conductivity to produce a variable surface impedance microstrip antenna with a several hundred GHz bandwidth. Specifically we report the optimization of a circular graphene microstrip patch antenna on silicon with an optimized return loss of -26 dB, a -10 dB bandwidth of 504 GHz and an antenna efficiency of -3.4 dB operating at a frequency of 2 THz. An improved antenna efficiency of -0.36 dB can be found at 3.5 THz but is accompanied by a lower bandwidth of about 200 GHz. Such large bandwidths and antenna efficiencies offers significant hope for a graphene based flexible directional antennas that can be employed for future THz local device-to-device communications not currently available. We also determine the real and imaginary components of the dielectric constant of graphene in the 1-10 THz regime.