Radio Frequencies
Mostrando 1-12 de 37 artigos, teses e dissertações.
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1. Corrigendum
Abstract Irregular terrains covered with forest vegetation represent a challenging scenario for radio planning. A case of particular interest is the one where a forest-covered high hill or mountain is interposed to the link, for which typical diffraction loss models usually apply as good approximations, even disregarding the vegetation influence. Pragmatic a
Braz. J. Psychiatry. Publicado em: 2021-06
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2. On the Use of UTD-Based Models for RF Path Loss Prediction Due to Diffraction on a Forest-Covered Ridge
Abstract Irregular terrains covered with forest vegetation represent a challenging scenario for radio planning. A case of particular interest is the one where a forest-covered high hill or mountain is interposed to the link, for which typical diffraction loss models usually apply as good approximations, even disregarding the vegetation influence. Pragmatic a
J. Microw. Optoelectron. Electromagn. Appl.. Publicado em: 2021-06
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3. 90 anos de Problemas da criação de Dostoiévski (1929-2019): o texto em seu e em nosso tempo
Abstract Irregular terrains covered with forest vegetation represent a challenging scenario for radio planning. A case of particular interest is the one where a forest-covered high hill or mountain is interposed to the link, for which typical diffraction loss models usually apply as good approximations, even disregarding the vegetation influence. Pragmatic a
Bakhtiniana, Rev. Estud. Discurso. Publicado em: 2021-06
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4. Editorial Comment: Penile cancer information on the internet: a needle in a haystack
Abstract A good wireless network design depends on technical and financial viability and a number of other criteria that must be met. Following the emergence of new technologies and services, such as 5G transmission and the reuse of frequencies, new work is being carried out to ensure a better design for a particular area. This study examines a discrete radi
Int. braz j urol.. Publicado em: 2020-12
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5. Optimum Positioning of Base Station for Cellular Service Devices Using Discrete Knowledge Model
Abstract A good wireless network design depends on technical and financial viability and a number of other criteria that must be met. Following the emergence of new technologies and services, such as 5G transmission and the reuse of frequencies, new work is being carried out to ensure a better design for a particular area. This study examines a discrete radi
J. Microw. Optoelectron. Electromagn. Appl.. Publicado em: 2020-12
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6. Double Patch Antenna Array for Communication and Out-of-band RF Energy Harvesting
Abstract This paper presents a patch antenna array topology for Simultaneous Wireless Information and Power Transfer (SWIPT) applications. The resulting Double Patch Antenna Array (DPA) is composed of two patch antennas operating at different frequencies and fabricated on a unique substrate. One of the patches operates at the 1.8 GHz mobile communication ban
J. Microw. Optoelectron. Electromagn. Appl.. Publicado em: 2020-09
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7. Prevalence of behavior problems and associated factors in preschool children from the city of Salvador, state of Bahia, Brazil
Objective: To identify the prevalence of internalizing and externalizing behavior problems among preschoolers from the city of Salvador, state of Bahia, Brazil, and their associations with maternal mental health and family characteristics. Methods: This was a cross-sectional study of 349 children aged 49 to 72 months, randomly selected from 20,000 househol
Rev. Bras. Psiquiatr.. Publicado em: 15/09/2015
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8. Extension of the Misme and Fimbel model for the estimation of the cumulative distribution function of the differential rain attenuation between two converging terrestrial links
A distribution-free model is presented for the cumulative distribution function of the differential rain attenuation between two co-channel converging terrestrial links operating at frequencies above 10 GHz. This is accomplished through an extension of the Misme and Fimbel model, which determines the cumulative distribution of the rain attenuation on an isol
J. Microw. Optoelectron. Electromagn. Appl.. Publicado em: 2013-06
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9. ANÁLISE DA DINÂMICA DA ATENUAÇÃO POR CHUVAS EM REGIÕES TROPICAIS / DYNAMIC ANALYSIS OF RAIN ATTENUATION IN TROPICAL REGIONS
The main effect causing non-availability in radio communication systems operating in frequencies above 10GHz, is the rain attenuation, particularly the heavy convective rain that is predominant in tropical regions. This thesis presents a detailed study and modelling of the dynamics of rain attenuation in terrestrial links and earthspace links, based on data
Publicado em: 2008
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10. Frequency synthesizers of 2.4 GHz from CMOS with 0.35 µm for ZigBee applications. / Sintetizador de freqüências de 2,4 GHz em CMOS, 0,35 µm para aplicações em ZigBee.
Frequency Synthesizers are circuits that generate pre-determined frequencies, used in both radio frequency reception and transmission. The Synthesizer circuits are composed by several blocks, such as Voltage-Controlled Oscillator (VCO), Prescaler, PFD (Phase/Frequency Detector), Charge Pump (CP), and Low Pass Filters (LPF). In 2003, an Integer-N architecture
Publicado em: 2008
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11. Modelo de regiões ativas em rádio freqüências / Model of active regions at radio frequencies
The goal of this work is to model in 3-D the solar atmosphere over active regions in order to reproduce the emission of these regions at radio frequencies. The model computes the radiative transfer equations for the thermal bremsstrahlung and gyro-resonance emission mechanisms. Because there are no measurements of magnetic fields intensities in the higher so
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 27/06/2007
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12. A multiagent framework for cognitive radio / Radios cognitivos : implemetnação de uma plataforma multiagentes
In frequencies lower than 3 GHz, a demand occurs out of the frequency spectrum due to the expansion of the wireless communication network, mainly for outdoor applications. Studies show that, there are great gaps of the frequency spectrum in the bands up to 3 GHz. The allocation model of the frequency spectrum needs reformulatiQn for the use of these gaps. Th
Publicado em: 2007