Full-wave analysis of a wide class of microstrip resonators fabricated on magnetized ferrites with arbitrarily oriented bias magnetic field

A numerical code has been developed for the full-wave determination of the resonant frequencies and quality factors of microstrip patches with right-angle corners of arbitrary shape in the case in which the substrate of the patches is a magnetized ferrite with arbitrarily oriented bias magnetic field. The code is based on the solution of an electric-field integral equation by means of Galerkin's method in the spectral domain. The evaluation of the infinite integrals arising from the application of the numerical method is efficiently carried out by means of a technique based on the interpolation of the spectral dyadic Green's function. The numerical results obtained indicate that microstrip patches fabricated on ferrite substrates present cutoff frequency regions in which resonances cannot occur owing to the excitation of magnetostatic modes. The limits of these cutoff regions are shown to be dependent on the orientation and the magnitude of the bias magnetic field, on the shape of the patches, and even on the nature of every particular resonant mode. The numerical results also show that the resonant frequencies of microstrip patches on magnetized ferrites can always be tuned over a wide frequency range provided the orientation of the bias magnetic field is suitably chosen

Full-wave analysis of tunable microstrip filters fabricated on magnetized ferrites

The method of moments in the spectral domain was employed in the rigorous full-wave numerical determination of the scattering parameters of two-port microstrip circuits fabricated on magnetized ferrite substrates. The numerical algorithm developed was applied to the analysis of microstrip bandpass filters fabricated on ferrites. Results show that the center frequency of the filters can be tuned over a wide range as a magnitude and/or the orientation of the bias magnetic field are varied. However, tunability was achieved at the expense of bandwidth reduction

Utilizando ARMSim y QtARMSim para la docencia de Arquitectura de Computadores

Muchos de los objetivos formativos de las asignaturas de introducción a la Arquitectura de Computadores se centran en aquellos aspectos que conforman la visión que un programador en lenguaje ensamblador tiene de un computador. Por regla general, para definir dichos objetivos se suele utilizar una arquitectura de computador concreta, que normalmente se selecciona con el doble criterio de que sea lo más sencilla posible y, a la vez, motive al estudiantado. La arquitectura ARM es una candidata idónea como vehículo conductor en la docencia de Arquitectura de Computadores. Por un lado, al estar basada en la arquitectura RISC (Reduced Instruction Set Computer), es relativamente sencilla. Por otro, se trata de una arquitectura actual y ampliamente difundida (especialmente en dispositivos móviles, smartphones y tabletas), lo que motiva al estudiantado. Para poder realizar prácticas sobre ARM es conveniente disponer de un simulador o de una herramienta de desarrollo sobre una máquina ARM. Puesto que dicha materia se explica en los primeros cursos, conviene que la aplicación seleccionada sea sencilla de utilizar y lo suficientemente flexible. Por otro lado, conviene que sea software libre, para poder adaptarla en caso necesario, y también multiplataforma y gratuita, para facilitar que el estudiante que lo desee pueda instalarla en su propio equipo. Tras evaluar distintas opciones, finalmente se optó por desarrollar y liberar un simulador propio de ARM, ARMSim, y una interfaz gráfica para dicho simulador, QtARMSim. El motor de simulación, ARMSim, y su interfaz, QtARMSim, han sido utilizados durante el curso 2014–15. Las críticas recibidas, tanto por los estudiantes como por los profesores de laboratorio, han sido muy positivas.Many of the training objectives of the Introduction to Computer Architecture modules focus on those aspects that conform the vision that an assembly language programmer has about a computer. As a rule, in order to define those objectives a concrete computer architecture is used following the following criteria: simplicity and ability to motivate students. ARM architecture is an ideal candidate for the didactics of Computer Architecture. On the one hand, being based on RISC architecture (Reduced Instruction Set Computer) it is rather simple. On the other, it is widely spread contemporary architecture (especially in mobile phones, smartphones and tablets), something that motivates students. In order to carry out ARM practice it would be convenient to have a simulator or a development tool on an ARM machine. Given the fact that this module is taught during the first academic years, it would also be convenient that the application selected was easy to use and flexible enough. Besides, it would be a good idea that it used freeware in order to be adapted if necessary, besides being free of charge and cross-platform-based so the students may install it in their own computers. After assessing several options, an ARM simulator (ARMSim) as well as a graphic interface for the latter (QtARMSim) were finally developed. The simulation engine, ARMSim, as well as its interface, QtARMSim, were used during the 2014/2015 academic year. The feedback received from both the students and lab lecturers have been remarkably positive

ARMSim y QtARMSim: simulador de ARM para docencia

Muchos de los objetivos formativos de las asignaturas de introducción a la Arquitectura de Computadores se centran en aquellos aspectos que conforman la visión que un programador en lenguaje ensamblador tiene de un computador. Por regla general, para definir dichos objetivos se suele utilizar una arquitectura de computadores concreta, que normalmente se selecciona con el doble criterio de que sea lo más sencilla posible y, a la vez, motive al estudiantado. La arquitectura ARM es una candidata idónea como vehículo conductor en la docencia de arquitectura de computadores. Por un lado, al estar basada en la arquitectura RISC (Reduced Instruction Set Computer), es relativamente sencilla. Por otro, se trata de una arquitectura actual y ampliamente difundida (especialmente en dispositivos móviles, smartphones y tablets), lo que motiva al estudiantado. Para poder realizar prácticas sobre ARM es conveniente disponer de un simulador o de una herramienta de desarrollo sobre una máquina ARM. Puesto que dicha materia se explica en los primeros cursos, conviene que la aplicación seleccionada sea sencilla de utilizar y lo suficientemente flexible. Por otro lado, conviene que sea libre, para poder adaptarla en caso necesario, y también multiplataforma y gratuita, para facilitar que el estudiante que lo desee pueda instalarla en su propio equipo. Tras evaluar distintas opciones, finalmente optamos por desarrollar y liberar nuestro propio simulador de ARM, ARMSim, y una interfaz gráfica para dicho simulador, QtARMSim. El simulador ARMSim y su interfaz, QtARMSim, han sido utilizados durante el primer semestre del curso 2014/15. Las críticas recibidas, tanto por los estudiantes como por los profesores de laboratorio, han sido muy positivas.Most of the learning objectives of introductory courses to Computer Architecture focus on those aspects that are related to the vision an assembly language programmer has of a computer. Generally, a particular computer architecture is used to define these objec- tives, which is usually selected with the double objective of being as simple as possible and to motivate the students. The ARM architecture is an ideal candidate as a vehicle architecture in teaching computer architecture. On the one hand, as it is based on RISC, it is relatively simple architecture. On the other, it is a widespread and current architecture (especially on mobile devices, smartphones and tablets), which motivates the students. To perform practices on ARM, it is convenient to have access either to a simulator or a development tool on an ARM machine. Since this matter is taught on the first years, the selected application should be simple to use and flexible enough. On the other hand, it ought to be free, as in freedom, to be able to adapt it if necessary, multiplatform and free, as in free beer, to facilitate that any student could install it on his own computer. After evaluating different alternatives, we finally opted for developing and releasing our own ARM simulator, ARMSim, and a GUI for this simulator, QtARMSim. The ARMSim simulator and its interface, QtARMSim, have been used during the first semester of 2014/15. The feedback received by students and laboratory teachers has been very positive

Synthesis Algorithm for “Quasi-Planar” Dielectric Lenses

In this work a phase-only synthesis algorithm based on a planar aperture model is proposed to design “quasi-planar” dielectric lenses with different radiation characteristics, either with a one-beam or two-beam pattern. The model is initially validated with both GO and full-wave simulations, and then with the measurement of a manufactured prototype in anechoic chamber. Both simulations and measurement show good agreement with the model results

Characteristics of aperture coupled microstrip antennas on magnetized ferrite substrates

The method of moments in the spectral domain is applied to the full-wave analysis of aperture coupled microstrip antennas in the case where the substrate of the antennas is a layered medium containing magnetized ferrites. The subsectional basis functions used in the analysis make it possible to handle patch antennas and coupling apertures with right angle corners of arbitrary shape. The numerical results obtained show that antennas on ferrite substrates fed by single microstrip lines can radiate both circular and linear polarization, the polarization state being dependent on the orientation of the ferrites bias magnetic field. For a given polarization state, the matching frequency band of the antennas can be tuned over a wide frequency range by adjusting the magnitude of the bias magnetic field. Also, the polarization state can be continuously tuned from circular to linear within the same frequency band by adjusting both the magnitude and the orientation of the bias magnetic field. Some measurements are presented in order to check the validity of the numerical algorithm developed

Contributions on Transmitarrays for Far-Field Applications

XI Encuentro Ibérico de Electromagnetismo Computacional-IIEC, 8-11 de noviembre de 2016, Asturias (España)Different contributions made to the development of Transmitarrays (TA) for Far-Filed applications are presented in this contribution. Firstly, a unit cell, based on four patches coupled by a slot or a symmetric cross, is introduced, and then, an arraybased model used to analyze a system formed by a TA and a planar lens in a time-efficient manner without using a full-wave method. Thus, both features are used to design and analyze the different prototypes reviewed in this contribution. That is, an ultra-thin planar lenses based on a 2-bit unit cell and a dualpolarized TA that has been designed in order to be used in polarized agile antenna. Thus, by rotating the feed of the system, a linear polarized antenna, it is possible to obtain any kind of polarization, form linear to circular. Finally, this TA has been used in a multibeam application fed with a network of quasi-yagi antenna

Simultaneous Synthesis of Arrays for Near Field Focusing and Far Field Constraints

Iberian Meeting on Computational Electromagnetics (12º, 2018, Coimbra

An Ultrathin 2-bit Near-Field Transmitarray Lens

A novel ultra-thin Near-Field 2-bit 24x24-element transmitarray lens working at X-Band is presented in this letter. The aim of this antenna is to focus in a point located in the Near-Field without using any complex feeding network. In order to obtain a planar lens with a very low profile, a 2-bit-design approach is used to diminish the number of layers used in the structure. The simulations have been done using a model based on the concept that the Near-Field of an array can be calculated as the sum of the Far-Field contributions of every single one of its elements. These are considered as plane apertures over which the tangential electric field is constant. In order to validate the results of this model, they are compared with both those obtained with a full-wave commercial software and those from measurements. Thus, a Near-Field-antenna is manufactured and measured showing the measurements good concordance with the results of the mode

Hormonal and Inflammatory Responses to Hypertrophy-Oriented Resistance Training at Acute Moderate Altitude

This research was funded by the Spanish Ministry of Science, Innovation and Universities, grant number PGC2018-097388-B-I00, by the Andalusian FEDER Operational Program, grant number A-SEJ-246-UGR18 and FPU pre-doctoral, grant number FPU18/00686 awarded to one of the authors.The authors thank the High Performance Center of Sierra Nevada, Spain and all the participants who volunteered for this investigation. The authors also thank Dymatize Europe for supplying the meal replacement supplements used in this study.This study investigated the effect of a traditional hypertrophy-oriented resistance training (R-T) session at acute terrestrial hypoxia on inflammatory, hormonal, and the expression of miR-378 responses associated with muscular gains. In a counterbalanced fashion, 13 resistance trained males completed a hypertrophic R-T session at both moderate-altitude (H; 2320 m asl) and under normoxic conditions (N; <700 m asl). Venous blood samples were taken before and throughout the 30 min post-exercise period for determination of cytokines (IL6, IL10, TNF alpha), hormones (growth hormone [GH], cortisol [C], testosterone), and miR-378. Both exercise conditions stimulated GH and C release, while miR-378, testosterone, and inflammatory responses remained near basal conditions. At H, the R-T session produced a moderate to large but nonsignificant increase in the absolute peak values of the studied cytokines. miR-378 revealed a moderate association with GH (r = 0.65; p = 0.026 and r = -0.59; p = 0.051 in N and H, respectively) and C (r = 0.61; p = 0.035 and r = 0.75; p = 0.005 in N and H, respectively). The results suggest that a R-T session at H does not differentially affect the hormonal, inflammatory, and miR-378 responses compared to N. However, the standardized mean difference detected values in the cytokines suggest an intensification of the inflammatory response in H that should be further investigated.Spanish Ministry of Science, Innovation and Universities PGC2018-097388-B-I00Andalusian FEDER Operational Program A-SEJ-246-UGR18FPU pre-doctoral FPU18/0068