Dual capacitive-inductive nature of periodic graphene patches: Transmission characteristics at low-terahertz frequencies

Abstract

We report on the dual nature (capacitive and inductive) of the surface impedance of periodic graphene patches at low-terahertz frequencies. The transmission spectra of a graphene-dielectric stack shows that patterned graphene exhibits both the low-frequency (capacitive) passband of metal patch arrays and the higher-frequency (inductive) passband of metal aperture arrays in a single tunable configuration. The analysis is carried out using a transfer-matrix approach with two-sided impedance boundary conditions, and the results are verified using full-wave numerical simulations. In addition, the Bloch-wave analysis of the corresponding infinite periodic structure is presented in order to explain the passband and stopband characteristics of the finite graphene-dielectric stack.

A Novel Tunable Antenna at THZ Frequencies Using Graphene-Based Artificial Magnetic Conductor (Amc)

“…The AMC unit cell made of graphene sheet is shown in Figure 1(a), and the surface impedance of the patch array at THz band can be approximated by [6,13,14] …”

“…In recent years, artificial magnetic conductor (AMC) ground plane has been widely used in the design and implementation of high-efficient and low-profile antennas [1][2][3][4][5][6]. In comparison with perfect electric conductor (PEC) ground plane, the AMC one can significantly reduce the separation distance from the radiator to the ground plane due to the additional capacitance introduced by the periodic pattern.…”

“…To achieve dynamic tuning capacity and broaden the AMC bandwidth, the capacitive lumped elements such as varactor diodes were inserted between the metallic AMC units [1,3]. In [4], an adjustable air-gap was used in the substrate to attain the frequency band selection, which can also be realized by adopting magnetic controllable ferrite material instead of traditional dielectric [6]. Nevertheless, at very high frequencies (for example THz), all of the tuning methods mentioned above become unrealistic because of the extremely small sizes of the antennas.…”

Design of broadband and tunable terahertz absorbers based on graphene metasurface: equivalent circuit model approach

“…Recently, graphene has been demonstrated as a viable alternative in realising THz absorbers because of its high THz absorption and tunability of surface conductivity [8][9][10]. With tunable conductivity of graphene sheet, propagation and absorption of electromagnetic wave on graphene can be controlled electronically [10][11][12][13][14].…”

Active substrate integrated terahertz waveguide using periodic graphene stack

“…[12][13][14][15][16][17] Moreover, 1-D graphene periodic structures and metallic-dielectric structures have attracted considerable attention in the literature, 18,19 which points out new opportunities in the field of metamaterial, photonic crystal, and surface plasmons. [20][21][22][23] To realizing the concept of true active waveguide, we propose an alternative method by tuning the dielectric property of periodic graphene stack to change the mode propagation constant of electromagnetic (EM) wave. We devise a configuration involving two rows of circular periodic graphene stack cylinders, instead of the metallic hole array and lumped component, so that the proposed SIW can operate over a large tunable range in the THz regime and provide a new platform to integrate all THz devices.…”