Graphene Antenna Research Articles

Wideband and low sidelobe graphene antenna array for 5G applications

Wideband and low sidelobe graphene antenna array for 5G applications

Graphene Based Circular Shaped Micro Strip Patch Antenna Array for 2.45 GHz ISM Band Application

Graphene based circular microstrip patch antenna array is presented in this paper. First a single circular patch to resonate at 2.45 GHz is designed in HFSS, then 1 × 2 array and 1 × 4 array are developed in order to improve the gain. The designed patch and arrays are fabricated using copper and graphene and the antenna parameters are measured and compared. This research work mainly focuses on two things; one is to improve the gain by developing array and the other one is to develop graphene antenna array using a simple, low cost printing method. Both are achieved, as the gain is improved by ~ 5 dB for 1 × 4 array when compared to single patch and the graphene antenna is fabricated and tested for its performance and found to be working perfectly as antenna in ISM Band.

Impact of Graphene Thickness on EM Modelling of Antenna

This paper presents illustrative electromagnetic modelling and simulation of graphene antenna using a two-dimensional graphene sheet of zero thickness and a three-dimensional graphene slab of finite thickness. The properties of the antenna are analyzed in terms of the S11 parameter, input impedance, VSWR, radiation pattern, and frequency reconfiguration using the full-wave electromagnetic simulator. Furthermore, this work numerically studies the modelling of graphene antenna using a three-dimensional graphene thin slab and the impact of graphene slab thickness on the performance of graphene antenna.

Tunable circularly polarized graphene antenna for THz applications

A technique is implemented for the generation of tunable circularly polarized THz wave using patterned graphene patch. The aspect ratio of graphene patch is selected to operate with the harmonics at frequency 1.7, 2.23, 3.26 and 3.41 THz covering three bands 1.67 - 1.73, 2.18 - 2.27 and 3.17 - 3.49 THz. The graphene patch is perturbed by inserting a patterned slot to generate the set of orthogonal magnetic dipoles and hence the CP wave. Insertion of slot shifts the resonant frequency of the generated harmonics at 2.95, 3.59, 4.89 and 5.068 THz covering the bands 2.86 - 2.99, 3.54 - 3.66 and 4.83 - 5.12 THz. Also, the dual-band circular polarization is obtained with 3-dB axial ratio bandwidth of 1.68 % (2.94 - 2.99 THz) and 0.4 % (4.99 - 5.01 THz) in the first and third operating band, respectively. Furthermore, the utilization of graphene in the radiator provides the frequency tunability of generated CP wave by varying the chemical potential. The antenna can be utilized in the biomedical applications at THz frequency band.

DESIGNING A DEPLOYABLE ENVIRONMENTAL SPIRAL CONICAL LOGARITHMIC GRAPHENE ANTENNA FOR SATELLITE COMMUNICATIONS

One of the main directions in the development of information technology is satellite communications (SС). Therefore, the elemental base of the SС is subject to increased requirements for weight and size characteristics and environmental friendliness. Research is needed on the use of new materials and technologies that will provide the required level of the above characteristics in order to achieve these requirements. One such promising technology is the printing of graphene inks on biodegradable substrates. Graphene inks do not corrode and are lighter than metal analogues. The possibility of using this technology allowed us to develop the direction of deployable antennas, which have the preferred weight and size characteristics, are easily transported and installed. The results of the development of an environmental spiral logarithmic graphene antenna for satellite communications, are presented. This antenna can be applied in the L-, S- and C-bands as well as GPS bands. A possible design and folding method is presented. The effect of the substrate's revolutions number on the S parameter is considered. The calculated radiation pattern in two planes is presented.

Dynamic Absorption Enhancement and Equivalent Resonant Circuit Modeling of Tunable Graphene-Metal Hybrid Antenna.

Plasmonic antennas are attractive optical components of the optoelectronic devices, operating in the far-infrared regime for sensing and imaging applications. However, low optical absorption hinders its potential applications, and their performance is limited due to fixed resonance frequency. In this article, a novel gate tunable graphene-metal hybrid plasmonic antenna with stacking configuration is proposed and investigated to achieve tunable performance over a broad range of frequencies with enhanced absorption characteristics. The hybrid graphene-metal antenna geometry is built up with a hexagon radiator that is supported by the Al2O3 insulator layer and graphene reflector. This stacked structure is deposited in the high resistive Si wafer substrate, and the hexagon radiator itself is a sandwich structure, which is composed of gold hexagon structure and two multilayer graphene stacks. The proposed antenna characteristics i.e., tunability of frequency, the efficiency corresponding to characteristics modes, and the tuning of absorption spectra, are evaluated by full-wave numerical simulations. Besides, the unity absorption peak that was realized through the proposed geometry is sensitive to the incident angle of TM-polarized incidence waves, which can flexibly shift the maxima of the absorption peak from 30 THz to 34 THz. Finally, an equivalent resonant circuit model for the investigated antenna based on the simulations results is designed to validate the antenna performance. Parametric analysis of the proposed antenna is carried out through altering the geometric parameters and graphene parameters in the Computer Simulation Technology (CST) studio. This clearly shows that the proposed antenna has a resonance frequency at 33 THz when the graphene sheet Fermi energy is increased to 0.3 eV by applying electrostatic gate voltage. The good agreement of the simulation and equivalent circuit model results makes the graphene-metal antenna suitable for the realization of far-infrared sensing and imaging device containing graphene antenna with enhanced performance.

Characterisation of tunable graphene antenna

Graphene is a unique material that can display tuning characteristics. This characteristic originates from its surface complex conductivity, which is controlled by a chemical potential. Most characteristics of tunable graphene antenna have been studied on Terahertz frequency range, thus making it difficult to be realised practically. Besides that, the standard antenna that uses switching components may have trouble during installation, and consume size as can be seen in the reconfigurable antenna. With the integration of this material, a tunable antenna based on graphene operating at microwave frequency range is proposed. The antenna was designed and fabricated at 15 GHz with a gate electrode placed behind it. They are connected to external DC bias during the measurement. The biasing is applied from 0 V to 30 V. The result shows that resonance frequency tuned about 20 MHz and reflection coefficient magnitude improved 1.24 dB. Following this, an analytical calculation on chemical potential was also derived for enhancing the graphene tunability. The count shows that at least 2.85 kV of the gate voltage is needed to vary the chemical potential and less than 0.26 µm of dielectric spacer thickness is suitable for tuning with a given condition, respectively.

A Review on the Development of Tunable Graphene Nanoantennas for Terahertz Optoelectronic and Plasmonic Applications.

Exceptional advancement has been made in the development of graphene optical nanoantennas. They are incorporated with optoelectronic devices for plasmonics application and have been an active research area across the globe. The interest in graphene plasmonic devices is driven by the different applications they have empowered, such as ultrafast nanodevices, photodetection, energy harvesting, biosensing, biomedical imaging and high-speed terahertz communications. In this article, the aim is to provide a detailed review of the essential explanation behind graphene nanoantennas experimental proofs for the developments of graphene-based plasmonics antennas, achieving enhanced light–matter interaction by exploiting graphene material conductivity and optical properties. First, the fundamental graphene nanoantennas and their tunable resonant behavior over THz frequencies are summarized. Furthermore, incorporating graphene–metal hybrid antennas with optoelectronic devices can prompt the acknowledgment of multi-platforms for photonics. More interestingly, various technical methods are critically studied for frequency tuning and active modulation of optical characteristics, through in situ modulations by applying an external electric field. Second, the various methods for radiation beam scanning and beam reconfigurability are discussed through reflectarray and leaky-wave graphene antennas. In particular, numerous graphene antenna photodetectors and graphene rectennas for energy harvesting are studied by giving a critical evaluation of antenna performances, enhanced photodetection, energy conversion efficiency and the significant problems that remain to be addressed. Finally, the potential developments in the synthesis of graphene material and technological methods involved in the fabrication of graphene–metal nanoantennas are discussed.

A graphene-based multiband antipodal Vivaldi nanoantenna for UWB applications

The design and optimization of an antipodal Vivaldi antenna using graphene material for ultra-wideband applications are described. A frequency-reconfigurable graphene antipodal Vivaldi antenna operating in the terahertz band is designed on a silicon dioxide substrate having thickness h = 3 µm. The antenna is designed and simulated using the finite integration technique in the commercially available Computer Simulation Technology (version 2016) electromagnetic simulation software. Due to its flexibility and hexagonal nature, the graphene-based THz antenna demonstrates multiband resonances. The results for the graphene-based antipodal Vivaldi antenna parameters, such as the return loss, bandwidth, voltage standing wave ratio (VSWR), three-dimensional (3D) and two-dimensional (2D) gain and directivity with co- and cross-polarization, and side-lobe levels, are analyzed. The designed graphene antenna exhibits four resonance bands in the terahertz range, covering the frequency range from 1 to 5 THz. The peak gain can reach 6.48 dBi with directivity of 8.3 dBi at the resonant frequency of 2.31 THz in the operating band from 1.44 to 2.4 THz.

Reconfigurable graphene antenna for THz applications: a mode conversion approach

A reconfigurable graphene antenna is designed and numerically analyzed. The antenna structure contains a radiating graphene patch and non-radiating graphene ring. The operating frequency of the antenna can be tuned by applying the gate voltage on the graphene patch. This proximity coupled antenna structure operates with the mode. In this configuration, the field is distributed in the form of horizontal magnetic dipole. The application of gate voltage at the periphery of graphene ring converts the field configuration to the form of the vertical electric dipole. Thus, the mode of operation of the antenna is changed to Consequently, the radiation pattern of the antenna can be steered in different directions as per the location of the applied gate voltage at the periphery of the graphene ring.

Enhancing the Performance of Polygon Monopole Antenna Using Graphene/TMDCs Heterostructures

In this letter, Laser Induced Graphene (LIG) as a low cost and versatile technique, was utilized to fabricate coplanar waveguide fed polygon monopole antenna on glass substrates. A modified LIG-MoS2 heterostructure based antennas were also fabricated and characterized. The formation of the graphene and the successful realization of the hybrid structures were examined and confirmed by several techniques including SEM, Raman and EDX. The conductivity as well as the reliability over large areas were demonstrated for both materials, concluding a significant improvement of LIG-MoS2 heterostructure over graphene antenna. Consequently, the two proposed antennas have shown up to 30% enhancement in gain with respect to a reference fabricated copper-based antenna.

Investigation of Phonon Scattering on the Tunable Mechanisms of Terahertz Graphene Metamaterials.

The influences of different kinds of phonon scatterings (i.e., acoustic (AC) phonon, impurity, and longitudinal optical (LO) phonon scatterings) on the tunable propagation properties of graphene metamaterials structures have been investigated, also including the effects of graphene pattern structures, Fermi levels, and operation frequencies. The results manifested that, at room temperature, AC phonon scattering dominated, while with the increase in temperature, the LO phonon scattering increased significantly and played a dominate role if temperature goes beyond 600 K. Due to the phonon scatterings, the resonant properties of the graphene metamaterial structure indicated an optimum value (about 0.5–0.8 eV) with the increase in Fermi level, which were different from the existing results. The results are very helpful to understand the tunable mechanisms of graphene functional devices, sensors, modulators, and antennas.

Analysis of Graphene Antenna Properties for 5G Applications.

The incoming 5G technology requires antennas with a greater capacity, wider wireless spectrum utilisation, high gain, and steer-ability. This is due to the cramped spectrum utilisation in the previous generation. As a matter of fact, conventional antennas are unable to serve the new frequency due to the limitations in fabrication and installation mainly for smaller sizes. The use of graphene material promises antennas with smaller sizes and thinner dimensions, yet capable of emitting higher frequencies. Hence, graphene antennas were studied at a frequency of 15 GHz in both single and array elements. The high-frequency antenna contributed to a large bandwidth and was excited by coplanar waveguide for easy fabrication on one surface via screen printing. The defected ground structure was applied in an array element to improve the radiation and increase the gain. The results showed that the printed, single element graphene antenna produced an impedance bandwidth, gain, and efficiency of 48.64%, 2.87 dBi, and 67.44%, respectively. Meanwhile, the array element produced slightly better efficiency (72.98%), approximately the same impedance bandwidth as the single element (48.98%), but higher gain (8.41 dBi). Moreover, it provided a beam width of 21.2° with scanning beam capability from 0° up to 39.05°. Thus, it was proved that graphene materials can be applied in 5G.

Resonant Tunneling Diode (RTD) Terahertz Active Transmission Line Oscillator with Graphene-Plasma Wave and Two Graphene Antennas

This study describes the design of a resonant tunneling diode (RTD) oscillator (RTD oscillator) with a RTD-gated-graphene-2DEF (two dimensional electron fluid) and demonstrates the functioning of this RTD oscillator through a transmission line simulation model. Impedance of the RTD oscillator changes periodically when physical dimension of the device is of considerable fraction of the electrical wavelength. As long as impedance matching is achieved, the oscillation frequency is not limited by the size of the device. An RTD oscillator with a graphene film and negative differential resistance (NDR) will produce power amplification. The positive electrode of the DC power supply is modified and designed as an antenna. So, the reflected power can also be radiated to increase RTD oscillator output power. The output analysis shows that through the optimization of the antenna structure, it is possible to increase the RTD oscillator output to 22 mW at 1.9 THz and 20 mW at 6.1 THz respectively. Furthermore, the RTD oscillator has the potential to oscillate at 50 THz with a matching antenna.

Parasitic‐coupled high‐gain graphene antenna employed on PBG dielectric grating substrate for THz applications

AbstractIn THz frequency region, the high‐gain miniaturized patch antenna is essential to overcome the atmospheric losses. A novel dual‐band miniaturized graphene antenna array with parasitic‐coupled feed and mounted on PBG dielectric grating substrate is proposed in the operating frequency band from 0.85 to 1.04 THz. The analysis of graphene surface conductivity, surface wave polariton (SPP) of photonic band gap (PBG) substrate, and the dielectric grating substrate has been done for the verification of a projected design. Parametric analysis of PBG radius, periodic perturbation of dielectric grating substrate, and mutual coupling distance has been verified to achieve the enhanced radiation characteristics of the antenna. The minimum return loss of −52.58 dB, VSWR of 1.005, impedance bandwidth of 33.34 GHz, the peak gain of 16.4 dB, and peak directivity of 17 dBi has been observed for the projected design. The parasitic‐coupled method is suitable to reduce the complexity of the antenna array and proposed design is useful in imaging, security using spectroscopy, and wireless communication applications.

A 5G graphene antenna produced by screen printing method

<p>The save and fast manufacturing are required in order to achieve 5G technology. However, there are many kinds of manufacturing antenna which are depending on material applied in the antenna itself. Each type of manufacturing also has its own advantages and drawback. In this article, a graphene antenna for 5G applications is manufactured using screen printing method. A fine mesh resolution of 120 µm is used to print the antenna accurately. This kind of printing has capability to produce antenna in less than 5 minutes. The antenna made by conductive graphene ink has size of 11.8 x 12.2 x 0.076 mm<sup>3</sup> and produced within a small amount of graphene ink. The measured antenna resonates at 15.04 GHz with reflection coefficient magnitude of -12.05 dB and percentage of impedance bandwidth is 30 % which is in the range of 13.3 to 18.0 GHz. The radiation pattern at E-plane and H-plane of the graphene antenna are simulated and measured where the result obtained are comparable.</p>

Proximity-coupled two-port multi-input-multi-output graphene antenna with pattern diversity for THz applications

A proximity coupled graphene patch based two-port multi-input-multi-output (MIMO) antenna with pattern diversity is implemented for THz applications. The MIMO and diversity performance parameters of the antenna like envelop correlation coefficient (ECC), diversity gain (DG) and mean effective gain (MEG) and total active reflection coefficient are calculated and found within the acceptable limits. The antenna offers the ECC <0.01, DG ≈10dB, and MEG ≤−3 dB. The antenna provides the 10 dB impedance bandwidth of 6.06% (1.76 −, 1.87 THz). The isolation between the ports of the proposed MIMO antenna remains more than 25 dB in the operating passband. The aspect ratio of graphene patch and physical parameters of the antenna are selected for obtaining the single mode operation with the resonance of TM12, mode. The utilization of the graphene material provides the flexibility in tuning the antenna response.

Electromagnetic modeling of a reconfigurable graphene-based metasurface using MoM-GEC method for 3D digital holography

ABSTRACTViewing the trend of beam shaping, beam steering, and metasurface holograms, a reconfigurable graphene-based metasurface is proposed and modeled using the method of moments combined with the generalized equivalent circuit (MoM-GEC) approach. The scattering state of each individual unit cell of the metasurface can be controlled by applying different biased voltages into the graphene antennas. In fact, the complex surface conductivity of graphene is introduced in our mathematical formulation in order to tune the magnitude and phase of the local reflection coefficient. Benefitting from this scalability, our graphene-based metasurface will regenerate a 3D medical hologram. The proposed approach is validated and paves the way for the generation a 3D digital holograms. There are several important areas where this study makes an original contribution such as medical imaging 3D displays.

Near-Field UHF RFID Transponder With a Screen-Printed Graphene Antenna

As a method of producing RFID tags, printed graphene provides a low-cost and eco-friendly alternative to the etching of aluminum or copper. The high resistivity of graphene, however, sets a challenge for the antenna design. In practice, it has led to using very large antennas in the UHF RFID far field tags demonstrated before. Using inductive near field as the coupling method between the reader and the tag is an alternative to the radiating far field also at UHF. The read range of such a near field tag is very short, but, on the other hand, the tag is extremely simple and small. In this paper, near field UHF RFID transponders with screen-printed graphene antennas are presented and the effect of the dimensions of the tag and the attachment method of the microchip studied. The attachment of the microchip is an important step of the fabrication process of a tag that has its impact on the final cost of a tag. Of the tags demonstrated, even the smallest one with the outer dimensions of 21 mm * 18 mm and the chip attached with isotropic conductive adhesive (ICA) was readable from a distance of 10 mm with an RF power marginal of 19 dB, which demonstrates that an operational and small graphene-based UHF RFID tag can be fabricated with low-cost industrial processes.

High radiation efficiency of coupled plasmonic graphene-based THz patch antenna utilizing strip slot ground plane removal

This paper proposes an enhancement radiation efficiency method of graphene-based patch antenna using partially strip slot ground plane removal. Graphene as a one-atom thickness (2D) supports surface plasmon polariton (SPP) of considerably decreasing wave length in comparing to the free space one. Based on this fact yields efficiency of graphene antennas is degraded. The effect of strip line ground plane removal reduces the losses due to dielectric substrate and surface waves. The proposed design has reached up to 90% at both radiation and total efficiency. Also due to using graphene, it can provide tunable conductivity derived from variable parameters. The graphene-based patch THz antenna is modeled to achieve the optimum parameter values.