Search results for "antennas"

A discussion of potential exposure metrics for use in epidemiological studies on human exposure to radiowaves from mobile phone base stations

2000

There is currently a high level of concern in many countries that exposure to radiowaves from mobile phone base stations may be hazardous to health. When investigating such suggested risks, epidemiologists need to define an exposure metric that can reliably discriminate between exposed and unexposed groups of people. We conducted a feasibility study to investigate if either short-term measurements of electric field strength, calculations of electric field strength, or distance from nearby mobile phone base stations could be used to develop a metric reflecting an individual's exposure to radiowaves. With electric field strengths in the range of 0.012-0.343 V/m, radiowaves from mobile phone b…

Optimization of multichip RFID tag antenna with genetic algorithm and method of moments

2013

A specific procedure is implemented for the optimization of passive part of multichip RFID tag antenna, based on the performance parameter in terms of newly developed concepts. Examples are given and significant improvements have been observed comparing with previous results, which verifies the approach.

Innovative systems based on optical nanoantennas for energy harvesting application

The purpose of this study is to outline the main guidelines for the design of arrays of optical rectennas aiming to harvest energy and for the optimization of the power transfer to an external load. In particular, the novelty of this study consists in introducing the concept of the integrated design between the array of optical rectennas and the harvesting circuit able to exploit the available energy. The design of the array represents the crucial point in order to optimize the power transfer between the antenna and the load and can influence the rectenna design. On the other hand, the maximum power transfer to the load has to be obtained under matching conditions between the array and the …

Design of a narrow-band filter based on the Brewster phenomenon for microwave applications

2017

A high-efficiency narrow-band filter based on a Dielectric Frequency-Selective Surface (DFSS) has been predicted theoretically for oblique plane-wave incidence. A DFSS showing total reflection at a frequency of 10.5 GHz, based on the Brewster phenomenon for TM polarization, has been designed with a single dielectric grating, showing extremely low-reflectance sidebands adjacent to the resonance peak. The angular and spectral response of the designed filter has been studied. In addition, dielectric ohmic losses have been accounted for in this structure. This work was supported by the Agencia Estatal de Investigación (AEI) and by the Unión Europea through the Fondo Europeo de Desarrollo Region…

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…

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.

Terahertz Time-Domain Spectroscopy setup based on photoconductive antennas

2016

Despite the technical difficulties in developing efficient and compact sources and detectors for Terahertz (THz) radiation, this region of the electromagnetic spectrum is attracting an ever-increasing interest, due to its peculiar and high-potential applications in several fields, such as wideband communications, medicine, biology, non-destructive testing, security and defense. Within such contexts, the most widespread approach aiming to deal with THz pulses is based on the THz Time-Domain Spectroscopy (THz-TDS) system. In this work, we present our experimental results obtained by means of a THz-TDS set-up based on photoconductive antennas for both the generation and detection stage. It is …

Terahertz time-domain spectroscopy based on photoconductive antennas

2016

In this work, we present our first experimental results obtained by means of a THz-TDS setup based on photoconductive antennas (PCAs). The main elements of the setup are: i) a mode-locked Ti:Sapphire femtosecond laser (Mai-Tai SP - Spectra Physics), providing optical pulses at 800±20 nm with a duration < 50 fs and repetition rate of 84 MHz; ii) two photoconductive antennas, made in LT-GaAs (Low-Grown Temperature Gallium Arsenide), operating as THz emitter and detector; iii) an optical delay line.

Radiometric Partial Discharge Detection: A Review

2023

One of the most common failures or breakdowns that can occur in high-voltage (HV) equipment is due to partial discharges (PDs). This occurs as a result of inadequate insulation, aging, harsh environmental effects, or manufacturing flaws. PD detection and recognition methods have gained growing attention and have seen great progress in the past decades. Radiometric methods are one of the most investigated detection approaches due to their immunity to electromagnetic interference (EMI) and their capabilities to detect and locate PD activities in different applications such as transformers, cables, etc. Several review articles have been published to classify and categorize these works. Nonethe…

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…