Search results for "antennas"

Feasibility, limitations and potentiality of UHF-RFID passive implants

2012

Implanted RFID may play an important role in the personal Healthcare of next future. Antenna embedded into prosthesis or into other implanted medical devices could permit to monitor physiological and pathological processes, providing a natural interconnection to remote services. The big technical challenge is to establish a stable RFID link with the interior of the human body in spite of the high electromagnetic losses of the tissues. By using parametric electromagnetic models and some early result, it is here investigated the potentiality and limitation of the UHF implants with special attention to the body district, the overall mass, and the size of the antennas.

Enhanced nanoscopy of individual CsPbBr3 perovskite nanocrystals using dielectric sub-micrometric antennas

2020

We demonstrate an efficient, simple, and low-cost approach for enhanced nanoscopy in individual green emitting perovskite (CsPbBr3) nanocrystals via TiO2 dielectric nanoantenna. The observed three- to five-fold emission enhancement is attributed to near-field effects and emission steering promoted by the coupling between the perovskite nanocrystals and the dielectric sub-micrometric antennas. The dark-field scattering configuration is then exploited for surface-enhanced absorption measurements, showing a large increase in detection sensitivity, leading to the detection of individual nanocrystals. Due to the broadband spectral response of the Mie sub-micrometric antennas, the method can be e…

Antenna Tapering Strategy for Near-Field Enhancement Optimization in Terahertz Gold Nanocavities

2019

Plasmonic nanoantennas (NAs) have received a growing attention in recent years due to their ability to confine light on sub-wavelength dimensions [1]. More recently, this property has been exploited in the terahertz (THz) frequency range (0.1–10 THz) for enhanced sensing and spectroscopy [2], as well as for more fundamental investigations [3]. These applications typically require high local electric fields that can be achieved by concentrating THz radiation into deeply sub-wavelength volumes located at the NAs extremities. However, the achievable near-field enhancement values are severely limited by the poor resonance quality factor of traditional rod-shaped THz NAs. Unlike what is commonly…

Performance Analysis of Cooperative V2V and V2I Communications Under Correlated Fading

2019

Cooperative vehicular networks will play a vital role in the coming years to implement various intelligent transportation-related applications. Both vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications will be needed to reliably disseminate information in a vehicular network. In this regard, a roadside unit (RSU) equipped with multiple antennas can improve the network capacity. While the traditional approaches assume antennas to experience independent fading, we consider a more practical uplink scenario where antennas at the RSU experience correlated fading. In particular, we evaluate the packet error probability for two renowned antenna correlation models, i.e., cons…

Optical Plasmonic Yagi-Uda Nano-Antennas Array for Energy Harvesting Applications

2020

Optical nanoantennas have been of great interest recently due to their ability to support a highly efficient, localized surface plasmon resonance and produce significantly enhanced and highly confined electromagnetic fields. The Yagi-Uda nanoantenna, an optical analogue of the well-established radiofrequency Yagi-Uda antenna, stands out by its efficient unidirectional light emission and enhancement. In this paper, the design of an optical plasmonic Yagi-Uda nanoantenna for energy harvesting application is proposed. The enhancement of the directivity is reached by means of an organization in array. The simulation results, carried out by 3D code CST Studio, show that the proposed nanoantenna …

Electrodynamic Characteristics of a Strip Antenna Located on a Plane Interface of a Resonant Magnetoplasma and an Isotropic Medium

2015

We study the electrodynamic characteristics of an antenna having the form of an infinitesimally thin, perfectly conducting narrow strip located on a plane interface of a resonant magnetoplasma and an isotropic medium. The antenna is perpendicular to an external magnetic field and is excited by a given voltage. Singular integral equations for the antenna current, on the basis of which the current distribution is found in the case of an infinitely long radiator, are obtained. The limits of applicability of an approximate method based on the transmission line theory for determining the current distribution and input impedance of the antenna are established. Within the framework of this method,…

Tunable Optical Antennas Using Vanadium Dioxide Metal-Insulator Phase Transitions

2019

Here, we investigate the possibility of exploiting the insulator-to-metal transition in vanadium dioxide (VO2) to tune and optically control the resonances of dipole nanoantennas in the visible near-infrared region. We compare the results obtained in the case of antennas completely made by VO2 with those of previous works and highlight the key role of the substrate to perform dynamical tuning. We also present a highly efficient configuration composed of dipole gold antenna loaded with VO2 and give some general guidelines to optimally exploit phase transitions to tune nanodevices.

GW170814: A Three-Detector Observation of Gravitational Waves from a Binary Black Hole Coalescence

2017

On August 14, 2017 at 10 30:43 UTC, the Advanced Virgo detector and the two Advanced LIGO detectors coherently observed a transient gravitational-wave signal produced by the coalescence of two stellar mass black holes, with a false-alarm rate of 1 in 27 000 years. The signal was observed with a three-detector network matched-filter signal-to-noise ratio of 18. The inferred masses of the initial black holes are 30.5-3.0+5.7M and 25.3-4.2+2.8M (at the 90% credible level). The luminosity distance of the source is 540-210+130 Mpc, corresponding to a redshift of z=0.11-0.04+0.03. A network of three detectors improves the sky localization of the source, reducing the area of the 90% credible regio…

Dependence of Terahertz Emission and Detection in Photoconductive Antennas on Laser Parameters

In this study, we employ a standard Terahertz time-domain spectroscopy (THz-TDS) setup based on two photoconductive antennas (PCAs) for THz radiation generation and detection. The characterization of the emission and detection performance as a function of the input pulse wavelength and bandwidth is performed.

Antennas for the detection of radio emission pulses from cosmic-ray induced air showers at the Pierre Auger Observatory.

2012

The Pierre Auger Observatory is exploring the potential of the radio detection technique to study extensive air showers induced by ultra-high energy cosmic rays. The Auger Engineering Radio Array (AERA) addresses both technological and scientific aspects of the radio technique. A first phase of AERA has been operating since September 2010 with detector stations observing radio signals at frequencies between 30 and 80 MHz. In this paper we present comparative studies to identify and optimize the antenna design for the final configuration of AERA consisting of 160 individual radio detector stations. The transient nature of the air shower signal requires a detailed description of the antenna s…