Dual-Band Tunable Recursive Active Filter

This letter presents a novel recursive active filter topology that provides dual-band performance, with independent tuning capability in both bands. The dual-band operation is achieved by using two independent feedback lines. Additionally, linear phase shifters based on left-handed cells are included in these two branches in order to tune the center frequency of both pass bands

Design method for actively matched antennas with non-foster elements

The design of electrically small antennas (ESAs) loaded with active non-Foster elements is a topic whose interest has grown in the last years. In this communication, a new strategy for the design of actively matched antennas loaded with non-Foster elements is presented. The analysis of different parameters, such as the sensitivity to non-Foster circuit placement, the overall antenna system stability, and current distributions, has to be considered in order to enhance the antenna performance. A design example using an ESA and its realization is presented to validate the proposed strategy.This work was supported in part by MINECO under the project TEC2013-47753-C3-2-R and RTC 2014-2380-4.Publicad

Mortero de cemento Portland con parafinas microencapsuladas

Se muestran resultados y análisis de características físicas y mecánicas de morteros con PCM

Antena de Parche Monopolar de Doble Frecuencia

A dual-frequency patch antenna with monopolar radiation patterns at both working frequencies is presented in this paper. The antenna design is based on a conventional patch with two concentric short-circuited conditions with a separating gap between them. Both shorting conditions are implemented with vias between the patch and the ground plane. These conditions impose two modes with a uniform electric field distribution both in phase and amplitude at the edge of the patch antenna. These modes result in a monopolar radiation pattern at two different frequencies. The working frequencies can be arbitrary set and depend on the patch dimensions and the location of the shorting vias. Two feeding strategies have been studied: a single coaxial probe which excites both monopolar modes and a different coaxial probe for each mode. A two-port design working at 2.6 GHz and 4.8 GHz is presented, obtaining the desired monopolar radiation pattern at both frequencies. High isolation between the feeding ports is achieved

Filtro Activo Recursivo con Divisores de Potencia Metamaterial Asimétricos

In this work, it is presented a recursive active filter implemented by means of unequal Wilkinson power dividers. These power combiners have been implemented by using metamaterial transmission lines based on complementary split ring resonators (CSRRs). The power dividers are designed in planar technology and thanks to the use of the metamaterial cells their dimensions have been reduced. Additionally, the designed recursive active filter presents a high gain and low noise at the same time that minimizes the number of employed lumped elements

Recursive Active Filter with Metamaterial Unequal Wilkinson Power Dividers

In this work, it is shown that it is possible to implement an unequal Wilkinson power divider with reduced dimensions by using metamaterial transmission lines based on complementary split ring resonators (CSRRs), in planar technology. In addition, this combiner has been used to implement a compact recursive active filter. Thanks to the use of the metamaterial combiner it is possible obtain a filter with small dimensions. Additionally, due to the asymmetry in the power divider it is possible obtain high gain and low noise at the same time that minimizes the number of lumped element

Estudio y Estrategias de diseño para amplificadores de doble banda de alto rendimiento. Estructuras con líneas CRLH y ECRLH.

In this paper two methods to design dual band and high efficiency power amplifiers using Composite Right/Left Hand (CRLH) and Extended Composite Right/Left Hand (ECRLH) transmission lines are described. The CRLH and ECRLH transmission lines, design procedure and design equations are presented. As example of application the design of an CE class amplifier appears. The non-linear phase response of a CRLH and ECRLH transmission line has been utilized to design arbitrary dual-band amplifiers. The simulations results are presented at the end of the paper, demonstrating the validity of the use of this type of lines in the design of amplifiers

Coverage analysis of Scopus: A journal metric approach

Our aim is to compare the coverage of the Scopus database with that of Ulrich, to determine just how homogenous it is in the academic world. The variables taken into account were subject distribution, geographical distribution, distribution by publishers and the language of publication. The analysis of the coverage of a product of this nature should be done in relation to an accepted model, the optimal choice being Ulrich’s Directory, considered the international point of reference for the most comprehensive information on journals published throughout the world. The results described here allow us to draw a profile of Scopus in terms of its coverage by areas – geographic and thematic – and the significance of peer-review in its publications. Both these aspects are highly pragmatic considerations for information retrieval, the evaluation of research, and the design of policies for the use of scientific databases in scientific promotion

Dipolos impresos multifrecuencia cargados con partículas metamateriales

Multi-frequency printed dipoles based on antipodal printed dipoles loaded with metamaterial particles are presented. Split Ring Resonators (SRRs) are used as metamaterial particles in order to obtain fully printed and planar antennas. First, a simplified model of these antennas is developed. This model is based on a printed dipole loaded with the equivalent circuit of the SRRs. This model shows that the working frequencies are very close to the self-resonant frequencies of the dipole and the SRRs. Moreover, a dualfrequency printed dipole is designed, manufactured and measured. This dipole works simultaneously at 1.32 GHz and 2.82 GHz. Finally, the previous idea is extended to increase the bandwidth of the dual-band dipoles and develop multifrequency printed dipoles (printed dipoles which work simultaneously at three or more frequencies). This is made by using SRRs with different dimensions