624 research outputs found
Graphene for Antenna Applications: Opportunities and Challenges from Microwaves to THz
The use of graphene for antennas and other electromagnetic passives could
bring significant benefit such as extreme miniaturization, monolithic
integration with graphene RF nanoelectronics, efficient dynamic tuning, and
even transparency and mechanical flexibility. Though recently different related
theoretical works have been presented, relatively few applications have been
proposed and realistically assessed. In this invited talk we will briefly
review the main properties of graphene and the state of the art in its
theoretical and experimental characterization. Then, we will discuss a number
of potential antenna applications from microwave to THz, providing in each case
a critical assessment of the benefits, limitations, and remaining issues
towards actual real-life implementations. Here we provide a brief overview of
different devices and associated developments in our group discussed in the
talk, including graphene antennas and reflectarrays at microwave and THz,
plasmonic switches, isotropic and anisotropic meta-surfaces, or graphene
RF-NEMS
Reconfigurable Reflectarrays and Array Lenses for Dynamic Antenna Beam Control: A Review
Advances in reflectarrays and array lenses with electronic beam-forming
capabilities are enabling a host of new possibilities for these
high-performance, low-cost antenna architectures. This paper reviews enabling
technologies and topologies of reconfigurable reflectarray and array lens
designs, and surveys a range of experimental implementations and achievements
that have been made in this area in recent years. The paper describes the
fundamental design approaches employed in realizing reconfigurable designs, and
explores advanced capabilities of these nascent architectures, such as
multi-band operation, polarization manipulation, frequency agility, and
amplification. Finally, the paper concludes by discussing future challenges and
possibilities for these antennas.Comment: 16 pages, 12 figure
Microwave study of field-effect devices based on graphene/aluminum nitride/graphene structures
Metallic gate electrodes are often employed to control the conductivity of graphene based field effect devices. The lack of transparency of such electrodes in many optical applications is a key limiting factor. We demonstrate a working concept of a double layer graphene field effect device that utilizes a thin film of sputtered aluminum nitride as dielectric gate material. For this system, we show that the graphene resistance can be modified by a voltage between the two graphene layers. We study how a second gate voltage applied to the silicon back gate modifies the measured microwave transport data at around 8.7 GHz. As confirmed by numerical simulations based on the Boltzmann equation, this system resembles a parallel circuit of two graphene layers with different intrinsic doping levels. The obtained experimental results indicate that the graphene-aluminum nitride-graphene device concept presents a promising technology platform for terahertz- to- optical devices as well as radio-frequency acoustic devices where piezoelectricity in aluminum nitride can also be exploited
Simulation and optimization of tuneable microstrip patch antenna for fifth-generation applications based on graphene
Microstrip patch antennas (MPAs) are known largely for their versatility in terms of feasible geometries, making them applicable in many distinct circumstances. In this paper, a graphene-based tuneable single/array rectangular microstrip patch antenna (MPA) utilizing an inset feed technique designed to function in multiple frequency bands are used in a fifth-generation (5G) wireless communications system. The tuneable antenna is used to eliminate the difficulties caused by the narrow bandwidths typically associated with MPAs. The graphene material has a reconfigurable surface conductivity that can be adjusted to function at the required value, thus allowing the required resonance frequency to be selected. The simulated tuneable antenna comprises a copper radiating patch with four graphene strips used for tuning purposes and is designed to cover a wide frequency band. The proposed antenna can be tuned directly by applying a direct current (DC) voltage to the graphene strips, resulting in a variation in the surface impedance of the graphene strips and leading to shifts in the resonance frequency
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