Characterization of Dielectric Properties of Graphene and Graphite Using the Resonant Cavity in 5G Test Band

Abstract

This paper presents a study about the dielectric constant ε_r, dielectric loss tangent tan g(δ) and effective electrical conductivity σ_e of graphene, graphite and graphene-bakelite combination using the resonant cavity method. For this purpose, cylindrical samples with diameter of 30 mm and thickness of 4.5 mm were analyzed taking into account the central frequency f₀ = 3.5 GHz, according to 5G technology standards. The constants ε_r and tan g(δ) were obtained from the resonance frequency f_a of measured scattering parameters (S-parameters), when the cavity was loaded with the samples. An empirical equation was developed to model the relation between f_a and ε_r. With this empirical equation it was found ε_r = 9.3203 and tan g(δ) = 0.7000 for graphene and ε_r = 17.1508 and tan g(δ) = 0.2700 for graphite. The addition of bakelite in combination with graphene allowed controlling the dielectric properties of these composites. The results, obtained in this macroscale characterization, are interesting for Telecommunications Engineering, especially in the development of radiation-absorbent material, which is suitable for mitigation of interference between different wireless communication systems.

Index Terms
Dielectric constant; dielectric loss constant; resonant cavity; graphene; graphite