Radio Frequency (RF)

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Structural, optical and electrical properties of ZnO thin films grown by radio frequency (rf) sputtering in oxygen atmosphere

Structural, optical and electrical properties of ZnO thin films grown by radio frequency (rf) sputtering in oxygen atmosphere

investigated as a function of the oxygen pressure during the growth of ZnO by radio frequency (rf) sputtering. The electrical behavior is explained in terms of the structural properties. Our results suggest that optimal oxygen partial pressure is 4 Pa for attaining a ZnO thin film as a buffer layer, with resistivity on the order of 10 3 Ω cm and an

10 Lee mas

20 GHz arbitrary radio frequency waveform generator based on incoherent pulse shaping

20 GHz arbitrary radio frequency waveform generator based on incoherent pulse shaping

The generation of arbitrary electromagnetic signals with 1-50 GHz frequency content is a current challenge for purely electronic systems. The ability to generate such broad bandwidth signals can have a positive impact on high-speed wireless communication systems, as well as finding interesting applications in radar, remote sensing and electronic equipment test measurements [1]. Thanks to the inherent broadband nature of photonics, all-optical approaches for arbitrary waveform generators (AWGs) can achieve easily this frequency range [2-7]. Actually, the upper limit in terms of the analog radio-frequency (RF) bandwidth that can be achieved with photonic approaches is only limited by the optoelectronic (O/E) conversion bandwidth.
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6 Lee mas

Measurements of time average series resonance effect in capacitively coupled radio frequency discharge plasma

Measurements of time average series resonance effect in capacitively coupled radio frequency discharge plasma

Ohmic and stochastic heating is well known in low pres- sure capacitively couple radio frequency (CCRF) plasma and various models have been proposed to describe the discharge and heating mechanism in such type of plasma. 1–8 The major contribution in Ohmic heating is due to the bulk and edge plasma, whereas the stochastic heating is due to the oscillat- ing plasma-sheath interface. Because of the oscillating ca- pacitance of the sheath capacitor(s) and the bulk plasma inductance in series, a resonance effect occurs which enhan- ces the heating mechanism, known as plasma series reso- nance (PSR) or electron series resonance (ESR). 9 Several authors have reported analytical and simulation calculations on enhancement of the Ohmic electron heating, 9–11 but stud- ies on stochastic heating in low pressure rf discharge plasma where they become more significant are rare. Recently, Lib- erman et al. described a model with self-consistent bias volt- age and compared the result with particle in cell simulation. 7 Enhancement of Ohmic and stochastic heating by resonance effects was calculated theoretically and found several Fou- rier components in rf plasma current. 12 It was also shown that the heating of electron is enhanced by a factor of 2–5 due to the self-excitation of the PSR. Semmler et al. experi- mentally observed several Fourier components of the dual frequency CCRF. 13 Highly energetic electrons produced by PSR effects have also been investigated. 14,15 As the PSR effect is concerned, very few references are found for its direct measurement. Klick et al. have invented a method to determine the electron density, collision rate of the electrons, and the power dissipated in a rf discharge plasma by self
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7 Lee mas

Two step method for the deposition of AlN by radio frequency sputtering

Two step method for the deposition of AlN by radio frequency sputtering

The most common techniques used for AlN growth are metalorganic vapor phase epitaxy [9,10], hydride vapor phase epitaxy [11] and mo- lecular beam epitaxy [12,13], all requiring expensive technology and high substrate temperature. Radio frequency (RF) reactive magnetron sputtering represents an attractive low-cost technique to synthesize AlN fi lms, allowing deposition in a wide range of temperatures and in both rigid and fl exible substrates [refs. 14 – 16].

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Diagnostic of Capacitively Coupled Low Pressure Radio Frequency Plasma: An Approach through Electrical Discharge Characteristic

Diagnostic of Capacitively Coupled Low Pressure Radio Frequency Plasma: An Approach through Electrical Discharge Characteristic

Abstract—Low temperature radio frequency plasma is widely used in low temperature plasma processing medium for material processing in many fields including microelectronics, aerospace, and the biology. For proper utilization of the process, it is very much important to know the plasma parameters. In this paper a technique is reported to determine the plasma parameters from the electrical discharge characteristic of a capacitivly couple radio frequency argon plasma. The homogeneous discharge model is modified to make it applicable in low pressure by incorporating the plasma series resonance effect. The effect on the plasma resistance by the change in drift velocity of the electron with rf electric filed is also considered. The electron density and temperature is found to be well agreed with the Langmuir probe diagnostic result, which is in the range of 0.5x10 10 to 4.5x10 10 cm -3 and 1.4 to 1.6 ev for wide range of rf power.
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Wait Time for Curative Intent Radio Frequency Ablation is Associated with Increased Mortality in Patients with Early Stage Hepatocellular Carcinoma

Wait Time for Curative Intent Radio Frequency Ablation is Associated with Increased Mortality in Patients with Early Stage Hepatocellular Carcinoma

Wait Time for Curative Intent Radio Frequency Ablation is Associated with Increased Mortality in Patients with Early Stage Hepatocellular Carcinoma.. Mayur Brahmania,* Osman Ahmed,* Meli[r]

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Dual radio frequency plasma source: Understanding via electrical asymmetry effect

Dual radio frequency plasma source: Understanding via electrical asymmetry effect

On the basis of the global model, the influences of driving voltage and frequency on electron heating in geometrically symmetrical dual capacitively coupled radio frequency plasma have been investigated. Consistent with the experimental and simulation results, non-monotonic behavior of dc self bias and plasma heating with increasing high frequency is observed. In addition to the local maxima of plasma parameters for the integer values of the ratio between the frequencies (n), ourstudies also predict local maxima for odd integer values of 2n as a consequence of the electrical asymmetry effect produced by dual frequency voltage sources. V C 2013 AIP Publishing LLC
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5 Lee mas

Morphology and arrangement of InN nanocolumns deposited by radio frequency sputtering: Effect of the buffer layer

Morphology and arrangement of InN nanocolumns deposited by radio frequency sputtering: Effect of the buffer layer

We present the structural and optical properties of (0001)-oriented nanocolumnar films of InN deposited on c-sapphire substrates by radio-frequency reactive sputtering. It is observed that the column density and dimensions are highly dependent on the growth parameters of the buffer layer. We investigate four buffer layers consisting of (i) 30 nm of low-growth-rate InN, (ii) 30 nm of AlN deposited on the unbiased substrate (us), (iii) 30 nm of AlN deposited on the reverse-biased substrate (bs), and (iv) a 60-nm-thick bilayer consisting of 30-nm-thick bs-AlN deposited on top of 30-nm-thick us-AlN. Differences in the layer nucleation process due to the buffer layer induce variations of the column density in the range of (2.5– 16) 10 9 cm 2 , and of the column diameter in the range of 87–176 nm. Best results in terms of mosaicity
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6 Lee mas

Antenna design solutions for radio frequency identification (RFID) tags based on metamaterial-inspired resonators and other resonant structures

Antenna design solutions for radio frequency identification (RFID) tags based on metamaterial-inspired resonators and other resonant structures

During the decades of the 50s and 60s, the development proceeded relatively slowly. In this period, ideas and patents related to the radio frequency identification were released (e.g., the patent entitled “Radio transmission systems with modulatable passive responder” by D.B. Harris), and further theoretical research was carried out (e.g., “Theory of Loaded Scatterers”, written in 1964 by R.F. Harrington). However, it was not until the invention and development of integrated circuits in the late 60s that RFID technology eventually could be implemented to a large number of applications in everyday life. In fact, as a result of the exponential reduction of the price and size of electronic devices, microwave transponders eventually fulfilled the requirements of being very small and cheap, setting the technological base to the RFID explosion of the following decades. An important contribution to the RFID ASIC development came in 1975, with the work entitled “Short-Range Radio-Telemetry for Electronic Identification Using Modulated Backscatter”, by Alfred Koelle, Steven Depp, and Robert Freyman, which introduced practical solutions in the modulation of the backscattered signal, and was at the base of the first practical passive tags with acceptable read range. Nevertheless, RFID was still highly developmental by that time, and the research efforts involved a large number of companies, such as Raytag and RCA in USA, Alfa Laval and Nedap in Europe, government laboratories and academic institutions.
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167 Lee mas

Electronic identification of goats: comparison of different types of radio-frequency and visual devices

Electronic identification of goats: comparison of different types of radio-frequency and visual devices

The use of passive radio frequency (RFID) technology for goat identification has become a key issue in recent years, especially in the European Union, where its compulsory use in sheep and goats is regulated. This paper reviews research carried out so far on the use of ear tags, injectable transponders, rumen boluses, and leg tags for goat identification, basing on their retention, readability, and retrieval easiness. The healing process of ear tags is conditioned by ear tag features and the biocompatibility of making materials. Moreover, ear tag retention is highly variable, in most cases not reaching the long-term (12 mo) readability of at least 98% required by the International Committee of Animal Recording. Button ear tags have been suggested to offer suitable readability, and are regarded for official use in different official programs. The subcutaneous injection of encapsulated transponders in different body locations has also been evaluated, mainly focusing on readability and migration results. Injection in the armpit offers the greatest readability in goats, although it is subjected to the greatest migration rates. Injection in the extremities has also been considered, although smaller transponders are used in this case, thereby compromising their reading distance. The main drawback of injectable transponders is their deficient retrieval at slaughter. The retention of rumen boluses has shown a remarkable variability in goats, and the influence of breed and feeding management on losses has been suggested. Most studies have indicated lower retention rates in goats than in other ruminant species. Even though, a regression model of bolus retention according to bolus weight and volume has been proposed, similarly to previous models established for sheep and cattle. According to this model, especially heavier and denser boluses are required in the case of goats to ensure that the device is permanently retained. Considering radio translucent materials currently available, suitable boluses for goat identification can be efficiently produced. Different RFID leg tags have also been proposed, especially for dairy goats in the milking parlor. The proper circumference of the leg band is recognized as a key aspect to be studied in this case as it seriously conditions the identification at early ages, while preventing the unlawful removal during the goat lifespan. Electronic readability of leg tags is greatly influenced by the type of transponder.
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159 Lee mas

Construction of a two-element radio interferometer

Construction of a two-element radio interferometer

Both receivers are made up of three main parts: a front end radio frequency (RF) part, a local oscillator (LO) and a back end intermediate frequency (IF) part (see block diagram on Figure 1). The RF stage uses the radio frequency signal received from the source, amplifies it and then applies a proper filter. Amplification is done since the signal coming from the source is very weak. Also, the signal is filtered to cut off undesired frequencies and select the appropriate one. The IF part, works with a lower frequency (the IF) obtained after mixing the RF with the LO. It also amplifies and selects the signal but includes an attenuator, to reduce the signal power and make it appropriate for analysis.
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36 Lee mas

Estudio de la tecnología, aplicaciones e implicaciones de los radio frequency identifiers (RFID)

Estudio de la tecnología, aplicaciones e implicaciones de los radio frequency identifiers (RFID)

S5.276 Atribución adicional: en Afganistán, Argelia, Arabia Saudita, Bahrein, Bangladesh, Brunei Darussalam, Burkina Faso, Burundi, Egipto, Emiratos Árabes Unidos, Ecuador, Eritrea, Etio[r]

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Propuesta de Implementación de un Sistema de Radio Frequency Identification (RFID) en la Colección de la EGAP de la Biblioteca del Tecnológico de Monterrey, Campus Ciudad de México -Edición Única

Propuesta de Implementación de un Sistema de Radio Frequency Identification (RFID) en la Colección de la EGAP de la Biblioteca del Tecnológico de Monterrey, Campus Ciudad de México -Edición Única

Como puede apreciarse, la tecnología de radio frecuencia ha estado entre nosotros desde mucho tiempo y surgió de la necesidad de mantener control preciso de ciertos productos y actividades, De esta diversidad surgieron también varios organismos e instituciones que se dedican ampliamente a su desarrollo y futuras aplicaciones. Como en el caso de la tecnología de los códigos de barras y debido al enfoque de este trabajo, no es posible ni pertinente incluir una descripción detallada de la evolución histórica de los sistemas de radar y menos aún abordar exhaustivamente los detalles técnicos de su funcionamiento. Baste con entender claramente los conceptos y saber que la tecnología de identificación por radiofrecuencia está emparentada con los sistemas de radar. Al tener en mente esta relación, no tendremos problemas para entender cómo es que funciona ni para evaluar la posibilidad de implementarla en un sistema bibliotecario.
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143 Lee mas

Propuesta de Implementación de un Sistema de Radio Frequency Identification (RFID) en la Colección de la EGAP de la Biblioteca del Tecnológico de Monterrey, Campus Ciudad de México  Edición Única

Propuesta de Implementación de un Sistema de Radio Frequency Identification (RFID) en la Colección de la EGAP de la Biblioteca del Tecnológico de Monterrey, Campus Ciudad de México Edición Única

Como puede apreciarse, la tecnología de radio frecuencia ha estado entre nosotros desde mucho tiempo y surgió de la necesidad de mantener control preciso de ciertos productos y actividades, De esta diversidad surgieron también varios organismos e instituciones que se dedican ampliamente a su desarrollo y futuras aplicaciones. Como en el caso de la tecnología de los códigos de barras y debido al enfoque de este trabajo, no es posible ni pertinente incluir una descripción detallada de la evolución histórica de los sistemas de radar y menos aún abordar exhaustivamente los detalles técnicos de su funcionamiento. Baste con entender claramente los conceptos y saber que la tecnología de identificación por radiofrecuencia está emparentada con los sistemas de radar. Al tener en mente esta relación, no tendremos problemas para entender cómo es que funciona ni para evaluar la posibilidad de implementarla en un sistema bibliotecario.
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141 Lee mas

Low frequency View of GW170817/GRB 170817A with the Giant Metrewave Radio Telescope

Low frequency View of GW170817/GRB 170817A with the Giant Metrewave Radio Telescope

The short gamma-ray burst ( GRB ) 170817A was the fi rst GRB associated with a gravitational-wave event. Due to the exceptionally low luminosity of the prompt γ -ray and the afterglow emission, the origin of both radiation components is highly debated. The most discussed models for the burst and the afterglow include a regular GRB jet seen off-axis and the emission from the cocoon encompassing a “ choked ” jet. Here, we report low radio frequency observations at 610 and 1390  MHz obtained with the Giant Metrewave Radio Telescope. Our observations span a range of ∼ 7 to ∼ 152 days after the burst. The afterglow started to emerge at these low frequencies about 60  days after the burst. The 1390  MHz light curve barely evolved between 60 and 150 days, but its evolution is also marginally consistent with an F ν ∝ t 0.8 rise seen in higher frequencies. We model the radio data and archival X-ray, optical, and high-frequency radio data with models of top-hat and Gaussian structured GRB jets. We performed a Markov Chain Monte Carlo analysis of the structured-jet parameter space. Though highly degenerate, useful bounds on the posterior probability distributions can be obtained. Our bounds of the viewing angle are consistent with that inferred from the gravitational-wave signal. We estimate the energy budget in prompt emission to be an order of magnitude lower than that in the afterglow blast wave.
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10 Lee mas

Design of a drone based measurement system for GSM signals

Design of a drone based measurement system for GSM signals

It is important to talk about Software Defined Radio (SDR), which is a radio communication system where components that have been typically implemented in hardware (e.g. mixers, filters, amplifiers, modulators/demodulators, detectors, etc.) are instead implemented by means of software on a personal computer or embedded system. A possible future development would be to use this system in instead of the GSM module. In addition to measure GSM signals, it would be possible to improve the reliability and accuracy of the experiments and to measure any radio frequency signal since this system’s bandwidth is totally reprogrammable.
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88 Lee mas

Laser-Induced Crystallization of Sputtered Unhydrogenated Silicon at Low Temperatures

Laser-Induced Crystallization of Sputtered Unhydrogenated Silicon at Low Temperatures

ABSTRACT: 10-µm-thick non-hydrogenated amorphous-silicon (a-Si) films were deposited at relatively high rates (≥ 10 Å/s) by radio-frequency magnetron sputtering (RFMS) on different large-area buffer-layer-coated glass substrates at deposition temperatures ranging from room temperature (RT) to 300ºC. These amorphous samples were subsequently crystallized by means of a continuous-wave diode laser, looking for conditions to reach liquid-phase crystallization. The influence of deposition conditions on the quality of the final micro-crystalline silicon films has been studied.
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5 Lee mas

Evaluation of Microbicidal Activity of Oxygen-Containing Plasmas using Biological Monitors with Different Lumen Calibers

Evaluation of Microbicidal Activity of Oxygen-Containing Plasmas using Biological Monitors with Different Lumen Calibers

against a standard load of Bacillus atrophaeus spores inoculated on glass carriers inside PVC catheters. The sterilization efficiency was studied as a function of plasma system (reactive ion etching or inductively coupled plasma), biological monitor lumen diameter, gas, radio frequency power, and sub-lethal exposi- tion time. After sterilization, the biological monitors were disassembled and the surviving bacteria were grown in trypticase soy broth using the most probable number technique. Plasma antimicrobial activity depended on the catheter’s internal diameter and radio frequency powers. The O 2 + H 2 O 2 mixture exhib-
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1 Lee mas

METODOLOGÍA PARA LA IMPLEMENTACIÓN DE LA TECNOLOGÍA IDENTIFICACIÓN POR RADIOFRECUENCIA EN ENTORNOS INDUSTRIALES Y SANITARIOS EN COLOMBIA.

METODOLOGÍA PARA LA IMPLEMENTACIÓN DE LA TECNOLOGÍA IDENTIFICACIÓN POR RADIOFRECUENCIA EN ENTORNOS INDUSTRIALES Y SANITARIOS EN COLOMBIA.

La tecnología de Identificación por Radio Frecuencia (RFID, Radio Frequency Identification) es una de las opcio- nes de identificación de productos más utilizadas en la actualidad, ya que permite mejorar los procesos relaciona- dos con el manejo de información de los productos en las cadenas de abastecimiento y en entornos sanitarios. Sus características convierten a RFID en la mejor alternativa para procesos de identificación de productos, frente a otros sistemas existentes, como los códigos de barra. Sin embargo, acorde a la literatura consultada, se encuentran pocas referencias a metodologías que guíen al usuario en la forma de implementar esta tecnología en los entornos indicados. El presente artículo propone una metodología para la implementación de RFID, para lo cual se realiza un proceso de investigación en donde se analizan metodologías existentes, logrando finalmente plantear una me- todología que aborda aspectos tecnológicos y gerenciales.
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Propuesta de un sistema de almacenamiento con Localización basada en RFID y WIFI

Propuesta de un sistema de almacenamiento con Localización basada en RFID y WIFI

2. RFID (Radio Frequency Identification) es una tecnología que utiliza la comunicación mediante el uso de ondas de radio para transferir datos entre un lector y una etiqueta electrónica adjunta a un objeto, con el propósito de identificación y seguimiento; consiste en etiquetas, lectores, software de la aplicación y hardware [11]. RFID hace que los procesos inteligentes sean posibles [7], como el seguimiento de cada objeto desde el punto de donde se encuentra.

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