Behavior of graphene based planar antenna at microwave and terahertz frequency

Abstract

In this paper, the behavior of radiation including the reconfiguration capability of planar metallic antenna structure using graphene in the microwave (MW) and terahertz (THz) frequency range is investigated. Different from the conventional reconfigurable metal planar antenna and graphene plasmonic THz antenna designs, this planar microstrip metal antenna structure is realized by placing a graphene layer in between the copper radiator and silicon dielectric. The design is inspired by the tunable conductivity behavior of graphene that can be achieved by applying a DC bias voltage across it. The antenna performance parameters such as frequency reconfiguration, VSWR, input impedance, efficiency, and radiation pattern are studied in both MW and THz frequencies. The radiation properties of the proposed antenna are studied at both MW and THz spectra by tuning the graphene conductivity via Fermi energy. It is found that, at MW and THz frequency, with respect to the unbiased condition, the antenna radiation efficiency is enhanced from 16% to 66% and from 26% to 69%, respectively, with the increase of Fermi energy from 0.5 eV to 0.8 eV. The efficiency of the antenna at both MW and THz can be further improved with the rise of the Fermi level of graphene. Moreover, the graphene based planar metal antenna structure provides easy frequency reconfiguration in the THz band due to its unique electronic and plasmonic properties at this frequency range, whereas, the presence of the graphene parasitic layer below metal radiator improves the impedance matching and radiation of the antenna at MW band.