Amplificador de potencia Doherty de 25 W, 70% de eficiencia y back off de salida de 6 dB para aplicaciones a 2,4 GHz, con control de VGS, PEAK

This paper shows the design and simulation results of a hybrid Doherty power amplifier. The amplifier has been designed at 2,4 GHz, obtaining power-added efficiency above 70 % for 6 dB output power back-off, together with a small signal gain of 17 dB. Design and analysis equations are presented considering class AB bias conditions for the main amplifier and class C for the peak one in back-off larger than 6 dB, and FET device assumption. An additional control on the bias point of the peak device has been carried out, in order to increase the gain on the Doherty region and ease the design of the peak branch. A Cree’s GaN-HEMT CGH40010F device has been used with a nonlinear model guarantied up to 6 GHz and with an expected output power of 10 W. The obtained output power is higher than 25-W. The simulation has been carried out using Agilent ADS CAD tools. The present design could present the state of the art in terms of continuous-wave (CW) characterization.Este artículo muestra el diseño y los resultados de simulación de un amplificador de potencia Doherty sobre tecnología híbrida. El amplificador fue diseñado a 2,4 GHz, obteniendo una eficiencia de potencia aditiva arriba del 70 % a 6-dB debajo de saturación, junto con una ganancia a pequeña señal de 17 dB. Las ecuaciones de análisis y diseño son presentadas considerando polarización clase AB para el amplificador principal y clase C para el amplificador auxiliar a 6-dB debajo de saturación, y dispositivos FET. Un control adicional sobre el punto de polarización del dispositivo auxiliar se ha llevado a cabo, para incrementar la ganancia en la región Doherty y facilitar el diseño de la rama auxiliar. Un dispositivo GaN-HEMT CGH40010 de Cree ha sido usado con un modelo no-lineal garantizado hasta 6-GHz y con una potencia de salida esperada de 10-W. La potencia de salida obtenida es mayor a 25-W. La simulación ha sido llevada a cabo usando Agilent ADS. El presente diseño representaría el estado del arte en términos de caracterización de onda continua (OC)

Amplificador de Potencia Doherty de 25 W, 70% de Eficiencia y Back Off de Salida de 6 dB para Aplicaciones a 2,4 GHz, con Control de VGS, PEAK

This paper shows the design and simulation results of a hybrid Doherty power amplifier. The amplifier has been designed at 2,4 GHz, obtaining power-added efficiency above 70 % for 6 dB output power back-off, together with a small signal gain of 17 dB. Design and analysis equations are presented considering class AB bias conditions for the main amplifier and class C for the peak one in back-off larger than 6 dB, and FET device assumption. An additional control on the bias point of the peak device has been carried out, in order to increase the gain on the Doherty region and ease the design of the peak branch. A Cree’s GaN-HEMT CGH40010F device has been used with a nonlinear model guarantied up to 6 GHz and with an expected output power of 10 W. The obtained output power is higher than 25-W. The simulation has been carried out using Agilent ADS CAD tools. The present design could present the state of the art in terms of continuous-wave (CW) characterizationEste artículo muestra el diseño y los resultados de simulación de un amplificador de potencia Doherty sobre tecnología híbrida. El amplificador fue diseñado a 2,4 GHz, obteniendo una eficiencia de potencia aditiva arriba del 70 % a 6-dB debajo de saturación, junto con una ganancia a pequeña señal de 17 dB. Las ecuaciones de análisis y diseño son presentadas considerando polarización clase AB para el amplificador principal y clase C para el amplificador auxiliar a 6-dB debajo de saturación, y dispositivos FET. Un control adicional sobre el punto de polarización del dispositivo auxiliar se ha llevado a cabo, para incrementar la ganancia en la región Doherty y facilitar el diseño de la rama auxiliar. Un dispositivo GaN-HEMT CGH40010 de Cree ha sido usado con un modelo no-lineal garantizado hasta 6-GHz y con una potencia de salida esperada de 10-W. La potencia de salida obtenida es mayor a 25-W. La simulación ha sido llevada a cabo usando Agilent ADS. El presente diseño representaría el estado del arte en términos de caracterización de onda continua (OC)

Caracterización experimental de las pérdidas de propagación en comunicaciones vehiculares a 700 MHz y 5,9 GHz

En esta Tesis Doctoral se realiza una caracterización experimental de las pérdidas de propagación del canal radio vehicular basada en una extensa campaña de medidas realizada en diferentes escenarios de propagación, todos ellos potenciales entornos de comunicaciones vehiculares. Se han realizado medidas en escenarios urbanos, suburbanos, rurales y de autovía, con condiciones reales de tráfico rodado, diferentes densidades de vehículos y condiciones de propagación. La sonda de canal empleada en las medidas ha sido diseñada e implementada con el propósito de realizar una caracterización en banda estrecha permitiendo analizar el efecto de las pérdidas de propagación y desvanecimiento multicamino. Las medidas se han realizado en la banda DSRC (Dedicated Short-Range Communications) a 5,9 GHz, adoptada en EEUU y Europa para comunicaciones vehiculares, y en la banda de 700 MHz propuesta por Japón para este tipo de comunicaciones. En este sentido, los resultados mostrados en esta Tesis Doctoral a 700 MHz son los primeros realizados en esta banda de frecuencia. Se han propuesto diferentes métodos de análisis de las medidas realizadas, permitiendo un extenso estudio de los parámetros que caracterizan las pérdidas de propagación. Se ha analizado el canal radio vehículo a vehículo (V2V, Vehicular-to-Vehicular) y el canal vehículo a infraestructura (V2I, Vehicular-to-Infrastructure), estableciendo un modelo lineal entre las pérdidas de propagación y el logaritmo de la distancia entre el transmisor y receptor. Se trata de un modelo sencillo, pero bastante exacto, que permite una fácil implementación en simuladores de redes vehiculares. A diferencia de otros trabajos previos, que solamente analizan valores medios de los parámetros del modelo de pérdidas, en esta tesis se presentan resultados que permiten conocer el rango de variación de dichos parámetros En la investigación realizada se ha analizado el impacto que las condiciones de propagación, en lo que respecta a línea de visión directa y obstrucción de la misma, tienen sobre el comportamiento de la atenuación introducida por el canal radio. Los resultados derivados de esta Tesis Doctoral pueden ser utilizados el diseño y evaluación de protocolos de comunicación bajo condiciones de propagación próximas a la realidad, así como en el diseño y planificación de las futuras redes vehiculares.Fernández González, HA. (2014). Caracterización experimental de las pérdidas de propagación en comunicaciones vehiculares a 700 MHz y 5,9 GHz [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/40370TESI

Dam removal Europe: refuting myths and supporting professionals

The removal of dams and weirs has been happening for decades. Since the 90’s a few countries have increased this tendency. USA has already removed at least 1,300 dams. What very few people know is that in Europe there have been over 3,500 barriers demolished already. In some European countries, like France, Sweden, Spain, Finland and UK dams are mainly being removed due to existing legislation, safety and security, the need to reach a good ecological status of their rivers for the Water Frame Directive and/or economical reasons. However, the lack of awareness, knowledge, support by decision makers and funding for dam removal are generally bottlenecks and most of the times is the cause of many dam removal failures. In addition, the Renewable Energy Directive requires the EU countries to fulfil at least 20% of its total energy needs with renewables by 2020, and amongst these renewables is hydropower. All this makes dam removal projects tremendously difficult to those who are willing to start removing old and useless dams, and automatically makes dam removal an uncomfortable subject to bring up for politicians. Europe requires a shift towards adaptive management of stream barriers, one that maximizes benefits and minimizes impacts, one that keeps efficient dams and removes obsolete and abandoned dams. The goals of Dam Removal Europe (www.damremoval.eu) are to improve citizens’ awareness about removing dams and refute myths, create a reference community of professionals, experts and starters, who generates and shares knowledge about dam removal and putting dam removal on the agenda of policy makers, directors and managers

Dam removal Europe: refuting myths and supporting professionals

The removal of dams and weirs has been happening for decades. Since the 90’s a few countries have increased this tendency. USA has already removed at least 1,300 dams. What very few people know is that in Europe there have been over 3,500 barriers demolished already. In some European countries, like France, Sweden, Spain, Finland and UK dams are mainly being removed due to existing legislation, safety and security, the need to reach a good ecological status of their rivers for the Water Frame Directive and/or economical reasons. However, the lack of awareness, knowledge, support by decision makers and funding for dam removal are generally bottlenecks and most of the times is the cause of many dam removal failures. In addition, the Renewable Energy Directive requires the EU countries to fulfil at least 20% of its total energy needs with renewables by 2020, and amongst these renewables is hydropower. All this makes dam removal projects tremendously difficult to those who are willing to start removing old and useless dams, and automatically makes dam removal an uncomfortable subject to bring up for politicians. Europe requires a shift towards adaptive management of stream barriers, one that maximizes benefits and minimizes impacts, one that keeps efficient dams and removes obsolete and abandoned dams. The goals of Dam Removal Europe (www.damremoval.eu) are to improve citizens’ awareness about removing dams and refute myths, create a reference community of professionals, experts and starters, who generates and shares knowledge about dam removal and putting dam removal on the agenda of policy makers, directors and managers

Remoción de sulfuro de dimetilo mediante biofiltración con bagazo de cañaino culado con Hyphomicrobium VS

La remoción de Sulfuro de dimetilo en una corriente de aire fue evaluada mediante la operación de un biofiltro utilizando bagazo de caña de azúcar como soporte de los microorganismos. El biofiltro fue inoculado con la bacteria Hyphomicrobium VS y se analizó el comportamiento del biofiltro para diferentes variables de operación como la eficiencia de remocion (ER) y la capacidad de eliminación(EC) obteniéndose los mejores resultados de remoción para un flujo de 0.03 m 3/h con una ER de 97.6 % y una EC de 0.61 gDMS/m 3h. Tambíen se realizó la caracterización al bagazo empleado como soporte, utilizando las técnicas de análisis elemental, espectroscopía infrarroja y microscopía electrónica de barrido

Path loss characterization for vehicular communications at 700 MHz and 5.9 GHz under LOS and NLOS conditions

In this letter, we present a path loss characterization of the vehicular-to-vehicular (V2V) propagation channel. We have assumed a path loss model suitable for vehicular ad hoc networks (VANETs) simulators. We have investigated the value of the model parameters, categorizing in line-of-sight (LOS) and non-LOS (NLOS) paths. The model parameters have been derived from extensive narrowband channel measurements at 700 MHz and 5.9 GHz. The measurements have been collected in typical expected V2V communications scenarios, i.e., urban, suburban, rural, and highway, for different road traffic densities, speeds, and driven conditions. The results reported here can be used to simulate and design the future vehicular networks.Fernández González, HA.; Rubio Arjona, L.; Rodrigo Peñarrocha, VM.; Reig, J. (2014). Path loss characterization for vehicular communications at 700 MHz and 5.9 GHz under LOS and NLOS conditions. IEEE Antennas and Wireless Propagation Letters. 13:931-934. doi:10.1109/LAWP.2014.2322261S9319341

Experimental Rician K-factor characterization in a laboratory environment at the 25 to 40 GHz frequency band

[EN] In this work, an analysis of the Rician K-factor in a laboratory environment from 25 to 40 GHz has been carried out. The variation of the estimated K-factor has been assessed in frequency from a channel measurements campaign in both line-of-sight (LOS) and non-LOS (NLOS) conditions. Mean values of the K-factor ranging from 0.48 to 3.43 dB for LOS conditions, and from -5.54 to -0.56 dB for NLOS conditions, have been derived. The results reported here enable us to get insight into the propagation channel characteristics and can be of interest to evaluate the performance of fifth-generation (5G) networks in laboratory environments.This work has been funded in part by the Spanish Ministerio de Economia, Industria y Competitividad under the project TEC2017-86779-C2-2-R, and by COLCIENCIAS in Colombia.Bernardo-Clemente, B.; Fernández, H.; Rodrigo Peñarrocha, VM.; Reig, J.; Rubio Arjona, L. (2020). Experimental Rician K-factor characterization in a laboratory environment at the 25 to 40 GHz frequency band. IEEE. 1121-1122. https://doi.org/10.1109/IEEECONF35879.2020.9329738S1121112

Analysis of Small-Scale Fading Distributions in Vehicle-to-Vehicle Communications

[EN] This work analyzes the characteristics of the small-scale fading distribution in vehicle-to-vehicle (V2V) channels. The analysis is based on a narrowband channelmeasurements campaign at 5.9GHz designed specifically for that purpose.Themeasurements were carried out in highway and urban environments around the city of Valencia, Spain.Theexperimental distribution of the small-scale fading is compared to several analytical distributions traditionally used to model the fast fading in wireless communications, such as Rayleigh, Nakagami-𝑚,Weibull, Rice, and 𝛼-𝜇 distributions. The parameters of the distributions are derived through statistical inference techniques and their goodness-of-fit is evaluated using the Kolmogorov-Smirnov (K-S) test. Our results show that the 𝛼-𝜇 distribution exhibits a better fit compared to the other distributions, making its use interesting to model the small-scale fading in V2V channels.This work has been funded in part by the Programa Estatal de Fomento de la Investigacion Cientifica y Tecnica de Excelencia del Ministerio de Economia y Competitividad, Spain, TEC2013-47360-C3-3-P, and the Departamento Administrativo de Ciencia, Tecnologia e Innovacion COLCIENCIAS en Colombia.Rodrigo Peñarrocha, VM.; Reig, J.; Rubio Arjona, L.; Fernández González, HA.; Loredo, S. (2016). Analysis of Small-Scale Fading Distributions in Vehicle-to-Vehicle Communications. Mobile Information Systems. 2016:1-7. https://doi.org/10.1155/2016/9584815S17201