Beam Steering of a Terahertz Semi Bow Tie Antenna Using Parasitic Graphene Ribbons
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Beam Steering of a Terahertz Semi Bow Tie Antenna Using Parasitic Graphene Ribbons Raheleh Basiri 1
&
Mahsa Aghazade-Tehrani 1 & Ehsan Zareian-Jahromi 1
Received: 20 December 2019 / Accepted: 19 March 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract In this paper, a reconfigurable beam-scanning planar antenna is proposed in terahertz frequencies. The presented structure consists of a semi bow tie antenna surrounded by circularly arranged parasitic pieces of graphene. The performance of the proposed antenna is investigated considering three different states where a PEC ground plane and a graphene ground layer with chemical potentials 0 (mode A) and 1 (mode B) are utilized at the bottom of the substrate. The proposed antenna is designed for utilization at a specific frequency of 1.2 THz in all these three states. The achieved antenna boresight and radiation pattern are altered through changing the conductivity of parasitic graphene elements and ground plane, which is obtained by controlling the corresponding chemical potential of the graphene segments. In addition, the parasitic graphene elements, located around the antenna, provide a high degree of freedom for altering the radiation pattern and antenna boresight. The parasitic elements operate as directors in modes A and B, whereas they act as reflectors in PEC ground state. Moreover, a high beam steering capability is obtained as chemical potentials of graphene elements are allocated between 0 and 1, whereas a PEC ground layer is employed at the bottom of the antenna. It should be noted that the gain and front-to-back ratio of the antenna are controlled using different chemical potentials of the graphene elements. A wide range of scan angles allocated between 0 and 180°, and toward the left and right directions in constant φ plane is achieved for the designed antenna. Keywords Antenna . Beam steering . Graphene . Reconfigurable . Terahertz
Introduction Terahertz (THz) regime surrounded with high-frequency edge of microwave band and long-wavelength edge of far-infrared light includes electromagnetic waves at frequencies between 300 GHz and 10 THz. Recently, many researches have been directed toward the development of THz sources and detectors, particularly for applications in medical imaging and security scanning systems [1]. Graphene is a honeycomb, two-dimensional lattice composed of carbon atoms [2]. Recently, this material
* Raheleh Basiri [email protected] Mahsa Aghazade-Tehrani [email protected] Ehsan Zareian-Jahromi [email protected] 1
Department of Electrical Engineering, Shiraz University of Technology, Shiraz 7155713876, Iran
has been intensively investigated due to its attractive properties and possible innovative applications, especially in THz frequency band [3–5]. Graphene complex surface conductivity is tunable by changing corresponding chemical potential (μc) according to the Kubo equation [6]. The variation of μc can be performed by applying a proper biasing voltage to the graphene sheet [7]. This pr
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