Non-homogeneous Fabry-Pérot antenna design process to improve aperture efficiency

A novel technique to design Fabry-Pérot antennas with non-homogeneous partially reflective surfaces (PRSs) is described. It uses a transmission line circuit model to efficiently obtain all necessary unit cell designs that satisfy the cavity resonance condition. This method allows an increase in directivity without reducing the bandwidth for a given footprint. Some design examples in the Ku-band are presented, showing the evolution from a simple single-layer PRS to a non-homogeneous two-layer one. The latter achieves an increase of about 3 dB in directivity while maintaining the bandwidth in electromagnetic simulations. This way, the gain-bandwidth product is improved from a value of 5 to almost 9, effectively raising the antenna efficiency.This work was supported by the Spanish Ministerio de Universidades (Programa para la Formación del Profesorado Universitario) under grant FPU20/03240, by MCIU/AEI/FEDER (Programa Estatal de I+D+i Orientada a los Retos de la Sociedad) under grant RTI2018-097098-J-I00, and by the regional government (Junta de Andalucía) PAIDI 2020 under grant PY20 00452. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Design and fabrication of a Fabry-Pérot cavity antenna for the Ku-band

A design of a directive antenna based on a Fabry-Pérot cavity is described, using a single metallic partially reflecting surface (PRS) in front of a coaxial-fed patch antenna. The main features of this type of antennas are their low profile and single feeding point. The design is initially carried out following an approximate ray model analysis using the extracted PRS characteristics from electromagnetic simulations. The antenna performance is also simulated, obtaining a directivity of 20.6 dBi for 15.25 GHz, and verifying its predicted behaviour. Furthermore, a prototype is manufactured at the group premises and some preliminary measurements are presented.The development of this research project is being possible thanks to the Initiation to Research Grant of the I Plan Propio de Investigaci´on y Transferencia of the Universidadnde Málaga. This project has also received funding from the Spanish MCIU/AEI/FEDER (Programa Estatal de I+D+i Orientada a los Retos de la Sociedad) under grant RTI2018- 097098-J-I00. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

On the eigenstate equivalent circuit for lossy asymmetric two-ports and its applications

An equivalent-circuit topology for two-port lossy non-symmetric reciprocal networks is presented [1]. The circuit topology is based on the eigenstate decomposition. The proposed circuit consists of two immittances and two transformers with a single complex turns ratio, as shown in Fig. 1. The only three complex parameters of the circuit are obtained from the eigenvalues and eigenvectors of the admittance or impedance matrix of the network in a straightforward way. The real parts of its immittances are always positive. Thus, the circuit is a powerful candidate for modeling asymmetric structures since it preserves some of the valuable properties of the symmetric lattice network: ability to separate the eigenstates and realizability of the real parts of the immittances. Indeed, it degenerates in the classic lattice network if the structure is symmetric. Two direct applications of the circuit are proposed. The first one is the design of asymmetric unit cells of leaky-wave antennas. A model can be found for the behavior of the two-port as a function of the degree of asymmetry using the proposed equivalent circuit topology. The new design methodology is simple and general, unlike the one proposed in [2]. The second application is the analysis and modeling of lossless and lossy bi-periodic scatterers [3]. It significantly simplifies their design, since it reduces the number of elements with respect to other equivalent circuits. Due to the capability of decomposition into the eigen excitations of the structure, the circuit provides an important physical insight. For different structures, the admittances have been successfully modeled using a few positive and frequency-independent RLC elements.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

Contains fulltext : 172380.pdf (publisher's version ) (Open Access

Performance analysis of equivalent-circuit topologies for periodic leaky-wave antenna rsymmetric Radiators

The traditional problem of broadside radiation degradation in leaky-wave antennas has been overcome in the past years with the introduction of some asymmetry in the radiator. This article analyses the performance of two equivalent-circuit topologies, previously proposed in the literature for asymmetric structures. The aim is to shed some light on the choice of the appropriate circuit when selecting the degree of asymmetry in the unit-cell of periodic leaky-wave antennas. The comparison is carried out through the extraction of the circuit parameters of three different structures and each of them with different degrees of asymmetry.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. MCIU/AEI/FEDER (Programa Estatal de I+D+i Orientada a los Retos de la Sociedad) referencia: RTI2018-097098-J-I00. Junta de Andalucía (Spain) PAIDI 2020 referencia: PY20 00452

Quorum sensing network in clinical strains of A. baumannii : AidA is a new quorum quenching enzyme

Acinetobacter baumannii is an important pathogen that causes nosocomial infections generally associated with high mortality and morbidity in Intensive Care Units (ICUs). Currently, little is known about the Quorum Sensing (QS)/Quorum Quenching (QQ) systems of this pathogen. We analyzed these mechanisms in seven clinical isolates of A. baumannii. Microarray analysis of one of these clinical isolates, Ab1 (A. baumannii ST-2-clon-2010), previously cultured in the presence of 3-oxo-C12-HSL (a QS signalling molecule) revealed a putative QQ enzyme (α/β hydrolase gene, AidA). This QQ enzyme was present in all nonmotile clinical isolates (67% of which were isolated from the respiratory tract) cultured in nutrient depleted LB medium. Interestingly, this gene was not located in the genome of the only motile clinical strain growing in this medium (A. baumannii strain Ab421-GEIH-2010 [Ab7], isolated from a blood sample). The AidA protein expressed in E. coli showed QQ activity. Finally, we observed downregulation of the AidA protein (QQ system attenuation) in the presence of HO (ROS stress). In conclusion, most of the A. baumannii clinical strains were not surface motile (84%) and were of respiratory origin (67%). Only the pilT gene was involved in surface motility and related to the QS system. Finally, a new QQ enzyme (α/β hydrolase gene, AidA protein) was detected in these strains

Small Towns, una realidad urbana en la Hispania romana (II)

Congreso Internacional MARQ Museo Arqueológico de Alicante: 26-28 de Octubre de 2021.Las ciudades pequeñas/Small Towns de la Península Ibérica son la abrumadora mayoría de las aproximadamente 400 ciudades que en época romana existieron en Hispania, es decir casi una quinta parte de las aprox. 2000 ciudades del Imperio Romano entero. De ahí que resulta de interés como punto de partida y base de estudio para la investigación, a pesar de las dificultades de definición. Mientras que los intentos anteriores buscaban utilizar el término en su calidad de clasificador para poder elaborar una jerarquía de asentamientos, y así asignar a cada uno de ellos su lugar en la clasificación y de esa manera describir sus propiedades correspondientes, aqui se propone la utilización del término Small Towns solo en su calidad de aspecto diferenciador con vistas a las capitales de provincia y de conventus, manteniendo toda su imprecisión para asentamientos con o sin trama urbana extendida, en un sentido amplio y genérico sin condicionantes ni jurídicos ni políticos. Las Small Towns suelen y pueden tener, con alguna variedad, características urbanas como edificios sacros y públicos, una muralla defensiva y casas urbanas. Sin embargo, suele observarse una desproporción entre la edificación pública y sacra por un lado y la privada por el otro en el sentido, de que la primera tenga una clara predominancia sobre la segunda tanto en calidad como en cantidad. Por otro lado les suelen faltar a las Small Towns otros criterios importantes habituales de los centros mayores como son la alta densidad de población, altos estándares de calidad, un cierto grado de diversificación económica, un plan urbanístico de circulación. Esas características ausentes son compensadas, por el otro lado, con un elemento del que se nutre a través de la carga generada por la (excesiva) edificación sacra y pública, y que le proporciona aquel atributo, que resume en sí la esencia de los centros mayores, que es la más típica y la que más los destaca: un exceso de significado.Esta publicación ha sido posible gracias a la financiación de la subvención global de la Junta de Extremadura, a través de la Consejería de Ciencia, Economía y Agenda Digital al Instituto de Arqueología de Mérida (Referencia 20164499).Peer reviewe