Application of RF-MEMS-Based Split Ring Resonators (SRRs) to the Implementation of Reconfigurable Stopband Filters : a Review

In this review paper, several strategies for the implementation of reconfigurable split ring resonators (SRRs) based on RF-MEMS switches are presented. Essentially three types of RF-MEMS combined with split rings are considered: (i) bridge-type RF-MEMS on top of complementary split ring resonators CSRRs; (ii) cantilever-type RF-MEMS on top of SRRs; and (iii) cantilever-type RF-MEMS integrated with SRRs (or RF-MEMS SRRs). Advantages and limitations of these different configurations from the point of view of their potential applications for reconfigurable stopband filter design are discussed, and several prototype devices are presented

The acceptance of newly introduced HR practices Some evidence from Spain on the role of management behavior and organizational climate

Purpose - HR practices are only effective if they are well accepted by employees. The purpose of this paper is to explore the effect of two forms of support on the acceptance of newly introduced HR practices (NHRPs): that of top managers and of supervisors. In addition, the authors analyze how these two forms of support work in conjunction with one another. The authors argue that a lack of consistency between the two impairs NHRP acceptance. The authors also explore variations in acceptance under different organizational climates. Design/methodology/approach - The analysis is based on an original sample of 307 employees from nine multinational companies operating in Spain. Multilevel regression analysis is used to test the hypotheses. Findings - The authors found that top management support, supervisor support, and innovation climate are all predictors of NHRP acceptance. The authors also found that low supervisor support reduces the effect of top management support. Finally, the authors found that innovation climate is not a substitute for management and supervisor support. Practical implications - The findings suggest that top management and supervisor behavior is critical to gaining employee acceptance of NHRPs, no matter how well designed such practices are or how well they address the needs of the organization and its employees. The findings also indicate that top managers and supervisors should coordinate the introduction of NHRPs, since employees perceive support signals from these two agents not only individually but also in conjunction. Originality/value - Recognizing that employee acceptance is an important determinant of the effectiveness of HR practices, the authors make a unique contribution to the literature by investigating some critical contextual enablers of acceptance.The authors thank financial support from the 7th EU Framework Program (Marie Curie IRG contract 205031), the Spanish Minister of Science (ECO2012-37314)

The Beauty of Symmetry: Common-mode rejection filters for high-speed interconnects and balanced microwave circuits

Common-mode rejection filters operating at microwave frequencies have been the subject of intensive research activity in the last decade. These filters are of interest for the suppression of common-mode noise in high-speed digital circuits, where differential signals are widely employed due to the high immunity to noise, electromagnetic interference (EMI) and crosstalk of differential-mode interconnects. These filters can also be used to improve common-mode rejection in microwave filters and circuits dealing with differential signals. Ideally, common-mode stopband filters should be transparent for the differential mode from DC up to very high frequencies (all-pass), should preserve the signal integrity for such mode, and should exhibit the widest and deepest possible rejection band for the common mode in the region of interest. Moreover, these characteristics should be achieved by means of structures with the smallest possible size. In this article, several techniques for the implementation of common-mode suppression filters in planar technology are reviewed. In all the cases, the strategy to simultaneously achieve common-mode suppression and all-pass behavior for the differential mode is based on selective mode-suppression. This selective mode suppression (either the common or the differential mode) in balanced lines is typically (although not exclusively) achieved by symmetrically loading the lines with symmetric resonant elements, opaque for the common-mode and transparent for the differential mode (common-mode suppression), or vice versa (differential-mode suppression).MINECO, Spain-TEC2013-40600-R, TEC2013-41913-PGeneralitat de Catalunya-2014SGR-15

Factors helping the HR function gain greater acceptance for its proposals and innovations: evidence from Spain

On the basis of the sense-making and sense-giving literature, this study addresses factors helping the HR function gain greater acceptance by employees for its proposals and innovations. Using an original sample of 298 employees from nine firms in Spain, we find that HR department credibility is only one of the factors that influence employees' acceptance. Other essential elements are top management and supervisor support. We also investigate the consequences that differential levels of support from supervisors and top managers can have for the acceptance of HR innovations, and we find that supervisor support carries more weight than that of top managers. Finally, we explore variations in the importance of the HR function credibility as an acceptance enabler under different organizational innovation climates. The results suggest that HR credibility plays an essential role independently of climateAuthors thank financial support from the 7th EU Framework Program (Marie Curie IRG contract 205031), the Spanish Minister of Science (ECO2012-37314), and Innovarh -a think tank designed to carry out research and foster innovative approaches to managing talent for companie

Filtros de microondas basados en metamateriales y en resonadores concentrados

Descripció del recurs: el 21-08-2008Consultable des del TDXTítol obtingut de la portada digitalitzadaRecientemente se ha abierto un nuevo campo de investigación en el área del electromagnetismo aplicado y de la ingeniería de microondas basado en el control de las propiedades electromagnéticas de ciertas estructuras periódicas artificiales conocidas como metamateriales. Debido a que las celdas constitutivas de este tipo de estructuras presentan unas dimensiones muy reducidas en términos de longitud de onda es posible diseñar, en base a este concepto, dispositivos que combinen un gran nivel de compactación y elevadas prestaciones. En esta tesis se han utilizado las propiedades de dichos medios para la implementación de filtros de microondas en tecnología planar. Particularmente se han desarrollado técnicas de síntesis que permiten el diseño de filtros con características controlables, en términos de ancho de banda, rizado en la banda de paso, colocación de ceros de transmisión en la banda de rechazo, etc. En este documento se pueden encontrar varios ejemplos de aplicación de estas técnicas, dando lugar a varios prototipos con respuestas en varios rangos de frecuencia, que van desde respuestas de banda estrecha hasta respuestas ultra anchas.In the last years, a new research field in the area of applied electromagnetism and microwave engineering based on the control of electromagnetic properties of artificial structures has taken a great interest. These structures are known as metamaterials. Due to the small dimensions of its constitutive cells it is possible to design, based on this concept, devices that combine high performance and compact dimensions. This thesis concerns the application of metamaterial technology to the synthesis of microwave filters in planar technology. In this document can be found a design methodology for each cell of the structure according to the desired frequency response of the filter (bandwidth, pass band ripple, location of transmission zeroes, etc). This methodology is also applicable to the design of filters with standard frequency responses (Chebyshev, Butterworth, etc). The theoretical work is also supported with experimental results of several prototypes with different bandwidths, from narrow band responses to ultra wide band filters

Retaining an ageing workforce: The effects of high-performance work systems and flexible work programmes

Older workers make up a growing proportion of the workforce, and research on how best to manage them is being conducted accordingly. Here, we explored the employee retention payoff of high-performance work systems (HPWS) and flexible work programmes (FWPs) when used with an older workforce. Drawing from the job demands-resources model, we hypothesised that HPWS retention outcomes decrease as the workforce ages, whereas the retention capacity of FWPs increases. We also explored how the parallel provision of HPWS and FWPs affects workforce retention in more ageing workplaces. The results suggest that workforce age composition affects the HPWS-retention relationship. However, the value of FWPs as retention tools does not vary significantly with workforce ageing. Furthermore, the provision of FWPs alongside HPWS appears to be a less-than-optimal approach to this retention. These findings may contribute to a better understanding of the HRM-performance relationship, while inspiring further research into successful age-differentiated HR strategies.Spanish Ministry of Economy, Industry and Competitiveness. Grant Number: ECO2015-68343-

Dual and broadband power dividers at microwave frequencies based on composite right/left handed (CRLH) lattice networks

CIMITECThis paper proposes a dual-band power divider operating at GHz frequencies and implemented by means of impedance transformers (also called inverters) based on lattice networks and transmission line sections. The dual-band functionality of the proposed device is achieved thanks to the composite right/left handed (CRLH) behavior of the impedance transformers, able to provide −90° and +90° phase shift at the first and second design frequencies, respectively, of the divider. By using such combination of transmission line sections and lattice networks, the characteristic impedance of the impedance transformers is roughly constant over wide bandwidths, with the results of broad operating bands. To demonstrate the possibilities of the approach, a prototype device is designed, fabricated and characterized

Differential microstrip lines with common-mode suppression based on electromagnetic band-gaps (EBGs)

CIMITECA technique for the suppression of the common mode in differential (balanced) microstrip lines, based on electromagnetic band-gaps (EBGs), is presented in this letter. It is demonstrated that by periodically modulating the common-mode characteristic impedance of the line and simultaneously forcing the differential-mode impedance to be uniform (and equal to the reference impedance of the differential ports), the common mode can be efficiently suppressed over a certain frequency band, while the line is transparent for the differential-mode. The main advantage of EBGs, as compared to other approaches for common-mode suppression in differential microstrip lines, is the fact that the ground plane is kept unaltered. Moreover, the design of the differential line is straightforward since the required level of common-mode suppression and bandwidth are given by simple approximate analytical expressions. As a design example, we report a four-stage common-mode suppressed differential line with 68% fractional bandwidth for the common-mode stopband centered at 2.4 GHz, and maximum common-mode rejection ratio (CMRR) of 19 dB at that frequency. Furthermore, we have designed and fabricated a six-stage double-tuned common-mode suppressed differential line in order to enhance the stopband bandwidth for the common mode around 2.4 GHz

Dual-band balanced bandpass filter with common-mode suppression based on electrically small planar resonators

The design of fully planar dual-band balanced bandpass filters with common-mode noise suppression is reported. The proposed filters are based on electrically small resonators coupled through admittance inverters. For design purposes, the circuit models of the considered resonators are reported. The key aspect for selective mode suppression (i.e., common-mode rejection in the differential-mode pass bands) is related to symmetry properties. Thus, for the differential-mode the symmetry plane is an electric wall, and the equivalent circuit for that mode provides dual-band functionality. Conversely, for the common-mode the symmetry plane is a magnetic wall, and the equivalent circuit exhibits a rejection band. As a proof of concept, the design of an order-2 Chebyshev dual-band balanced bandpass filter with center frequencies f₁= 1.8 GHz (GSM band) and f₂=2.4 GHz (Wi-Fi band), fractional bandwidth FBW= 7%, and ripple level LA1= 0.01 dB is reported. Index Terms-Balanced filters, common-mod

Common-mode suppressed differential bandpass filter based on open complementary split ring resonators fabricated in microstrip technology without ground plane etching

A differential (or balanced) bandpass filter based on open complementary split ring resonators (OCSRRs) coupled through admittance inverters is presented in this article. Pairs of OCSRRs are symmet- rically placed in a mirror configuration between the strips of the differential line and are modeled by means of two series connected parallel resonators. For the differential (odd) mode, there is a virtual ground at the connecting plane between the OCSRR pairs, and the structure is roughly described by the canonical model of a bandpass filter, consisting of a cascade of shunt resonators coupled through admittance inverters. It is demonstrated that, through a proper design of the OCSRR stages, the common mode noise in the vicinity of the differential filter pass band can be efficiently suppressed. Due to the differential mode operation of the filter, it is not necessary to incorporate metallic vias to ground the OCSRRs. Moreover, as compared to other differential filters based on OCSRRs, defected ground structures are not present in the proposed filters. To illustrate the potential of the approach, two balanced bandpass filters are designed, fabricated, and characterized