Analysis of the finite difference time domain technique to solve the Schrödinger equation for quantum devices

An extension of the finite difference time domain is applied to solve the Schrödinger equation. A systematic analysis of stability and convergence of this technique is carried out in this article. The numerical scheme used to solve the Schrödinger equation differs from the scheme found in electromagnetics. Also, the unit cell employed to model quantum devices is different from the Yee cell used by the electrical engineering community. A bound for the time step is derived to ensure stability. Several numerical experiments in quantum structures demonstrate the accuracy of a second order, comparable to the analysis of electromagnetic devices with the Yee cell.a!Electronic mail: [email protected] b!Electronic mail: [email protected] c!Electronic mail: [email protected] d!Electronic mail: [email protected]

Transmission properties at microwave frequencies of two-dimensional metallic lattices

The transmission properties of different metallic photonic lattices (square and rectangular) have been experimentally studied. A numerical algorithm based on time domain finite differences has been used for simulating these photonic structures. The introduction of defects in the two-dimensional metallic lattice modifies its transmission spectrum. If metal rods are eliminated from (or added to) the lattice, extremely narrow peaks are observed at some particular frequencies below (or above) the band pass [email protected] ; [email protected]

Design & Optimization of Large Cylindrical Radomes with Subcell and Non-Orthogonal FDTD Meshes Combined with Genetic Algorithms

The word radome is a contraction of radar and dome. The function of radomes is to protect antennas from atmospheric agents. Radomes are closed structures that protect the antennas from environmental factors such as wind, rain, ice, sand, and ultraviolet rays, among others. The radomes are passive structures that introduce return losses, and whose proper design would relax the requirement of complex front-end elements such as amplifiers. The radome consists mostly in a thin dielectric curved shape cover and sometimes needs to be tuned using metal inserts to cancel the capacitive performance of the dielectric. Radomes are in the near field region of the antennas and a full wave analysis of the antenna with the radome is the best approach to analyze its performance. A major numerical problem is the full wave modeling of a large radome-antenna-array system, as optimization of the radome parameters minimize return losses. In the present work, the finite difference time domain (FDTD) combined with a genetic algorithm is used to find the optimal radome for a large radome-antenna-array system. FDTD uses general curvilinear coordinates and sub-cell features as a thin dielectric slab approach and a thin wire approach. Both approximations are generally required if a problem of practical electrical size is to be solved using a manageable number of cells and time steps in FDTD inside a repetitive optimization loop. These approaches are used in the full wave analysis of a large array of crossed dipoles covered with a thin and cylindrical dielectric radome. The radome dielectric has a thickness of ~λ/10 at its central operating frequency. To reduce return loss a thin helical wire is introduced in the radome, whose diameter is ~0.0017λ and the spacing between each turn is ~0.3λ. The genetic algorithm was implemented to find the best parameters to minimize return losses. The inclusion of a helical wire reduces return losses by ~10 dB, however some minor changes of radiation pattern could distort the performance of the whole radome-array-antenna system. A further analysis shows that desired specifications of the system are preserved

Subjective symptoms related to GSM radiation from mobile phone base stations : a cross-sectional study

Objectives: We performed a reanalysis of the data from Navarro et al., 2003, in which health symptoms related to microwave exposure from mobile phone base stations (BS) were explored, including data obtained in a retrospective inquiry about fear of exposure from BS. Design: Cross-sectional study. Setting: La Ñora (Murcia), Spain. Participants: Participants with known illness in 2003 were subsequently disregarded: 88 participants instead of 101 (in 2003) were analysed. Since weather circumstances can influence exposure, we restricted data to measurements made under similar weather conditions. Outcomes and methods: A statistical method indifferent to the assumption of normality was employed: namely, binary logistic regression for modelling a binary response (e.g. suffering fatigue (1) or not (0)), and so exposure was introduced as a predictor variable. This analysis was carried out on a regular basis and bootstrapping [95% percentile method] was used to provide more accurate confidence intervals. Main outcome measures Results: The symptoms most related to exposure were: lack of appetite [odds ratio (OR)] = 1.58, 95% confidence interval (95%CI) = 1.23-2.03; lack of concentration [OR = 1.54, 95% CI = 1.25- 1.89]; irritability [OR = 1.51, 95% CI = 1.23-1.85]; and trouble sleeping [OR = 1.49, 95% CI = 1.20-1.84]. Changes in -2 log likelihood showed similar results. Concerns about the BS were strongly related with trouble sleeping [OR = 3.12, 95% CI = 1.10-8.86]. The exposure variable remained statistically significant in the multivariate analysis. The bootstrapped values were similar to the asymptotic confidence intervals. Conclusion: This study confirms our preliminary results. We observed that the incidence of most of the symptoms was related to exposure levels ¿ independently of the demographic variables and some possible risk factors. Concerns about adverse effects from exposure, despite being strongly related with sleep disturbances, do not influence the direct association between exposure and sleep

A New Approach to the Modeling of Anisotropic Media with the Transmission Line Matrix Method

A reformulation of the Transmission Line Matrix (TLM) method is presented to model non-dispersive anisotropic media. Two TLM-based solutions to solve this problem can already be found in the literature, each one with an interesting feature. One can be considered a more conceptual approach, close to the TLM fundamentals, which identifies each TLM in Maxwell's equations with a specific line. But this simplicity is achieved at the expense of an increase in the memory storage requirements of a general situation. The second existing solution is a more powerful and general formulation that avoids this increase in memory storage. However, it is based on signal processing techniques and considerably deviates from the original TLM method, which may complicate its dissemination in the scientific community. The reformulation presented in this work exploits the benefits of both methods. On the one hand, it maintains the direct and conceptual approach of the original TLM, which may help to better understand it, allowing for its future use and improvement by other authors. On the other hand, the proposal includes an optimized treatment of the signals stored at the stub lines in order to limit the requirement of memory storage to only one accumulative term per field component, as in the original TLM versions used for isotropic media. The good behavior of the proposed algorithm when applied to anisotropic media is shown by its application to different situations involving diagonal and off-diagonal tensor properties

Radio definida por software y docencia en línea: experiencia en el Grado en Ingeniería Telemática

[EN] Devices based on software defined radio have been used in the last 6 years as motivating elements in the laboratory practices of digital communications courses at the Degree in Telematics Engineering of the University of Valencia. However, the development of these practices requires giving access to some hardware devices that are physically located in the laboratories of the School of Engineering. In this contribution, taking into account the current situation of hybrid learning and a possible transition to remote learning due to the COVID-19 pandemic, a system that allows the remote interaction with the software defined radio devices is proposed. This remote access system, in addition to allowing these devices to be used in laboratory practices even in a remote learning context, would allow students to access them outside laboratory practice hours. The results obtained in the Digital Communications Theory course demonstrate the high potential for motivation and increased academic involvement provided by the use of these devices, especially in contexts with low academic involvement, such as the 2020-2021 academic year.[ES] Los dispositivos de radio definida por software se han utilizado en los últimos 6 años como elementos dinamizadores de las prácticas de laboratorio en las asignaturas de la materia de comunicaciones digitales del Grado en Ingeniería Telemática de la Universitat de València. Sin embargo, el desarrollo de estas prácticas requiere el acceso a unos dispositivos hardware que están localizados físicamente en los laboratorios de la Escuela Técnica Superior de Ingeniería. En esta contribución, atendiendo a la actual situación de docencia semipresencial y de un posible paso a docencia en línea debido a la pandemia de COVID-19, se plantea establecer un sistema que permita la interacción remota con los dispositivos de radio definida por software. Este sistema de acceso remoto, además de permitir que se sigan utilizando estos dispositivos en las prácticas de laboratorio aún en un contexto de docencia en línea, permitiría el acceso del alumnado a ellos fuera del horario de prácticas de laboratorio. Los resultados obtenidos en la asignatura de Teoría de la Comunicación demuestran el alto potencial de motivación y de aumento de la implicación académica que presentan estos dispositivos, especialmente en contextos con una implicación académica baja, como es el curso académico 2020-2021.Este trabajo ha sido financiado por el “Vicerectorat d’Ocupació i Programes Formatius” de la Universitat de València a través del proyecto UV-SFPIE PID-1353656. Sandra Roger agradece la finaciación recibida a través del contrato postdoctoral RYC-2017-22101 y el proyecto GV/2020/046.Botella Mascarell, C.; Roger, S.; Soriano Asensi, A.; Perez, J.; Segura Garcia, J.; Felici Castell, S.; Navarro Camba, EA. (2021). Radio definida por software y docencia en línea: experiencia en el Grado en Ingeniería Telemática. En IN-RED 2021: VII Congreso de Innovación Edicativa y Docencia en Red. Editorial Universitat Politècnica de València. 267-277. https://doi.org/10.4995/INRED2021.2021.13687OCS26727

Design and Study of a Wide-Band Printed Circuit Board Near-Field Probe

Magnetic near-field probes (NFP) represent a suitable tool to measure the magnetic field level from a small electromagnetic interference (EMI) source. This kind of antenna is useful as a magnetic field probe for pre-compliance EMC measurements or debugging tasks since the user can scan a printed circuit board (PCB) looking for locations with strong magnetic fields. When a strong H-field point is found, the designer should check the PCB layout and components placement in that area to detect if this could result in an EMI source. This contribution focuses on analyzing the performance of an easy to build and low-cost H-field NFP designed and manufactured using a standard PCB stack-up. Thereby, the frequency range and sensitivity of the NFP-PCB are analyzed through a Finite Element Method (FEM) simulation model that makes it possible to evaluate its sensibility and effective frequency range. The numerical results obtained with the FEM models are validated against measurements to verify the design and performance of our NFP. The FEM model reproduces the experimental procedure, which is used to evaluate the performance of the NFP in terms of sensitivity by means of the simulated near-field distribution. The NFP-PCB has almost a flat response from 180 MHz to 6 GHz, with an almost perfect concordance between numerical and experimental S21 results. The numerical results show an average transmission loss of −27.9 dB by considering the flat response bandwidth, whereas the experimental one is −29.7 dB. Finally, the designed NFP is compared to two high-quality commercial probes in order to analyze its performance

Incorporando dispositivos de radio definida por software en la materia de Comunicaciones Digitales: del grupo piloto a la gran clase

La innovación educativa es un proceso que se extiende más allá de un curso académico. En su desarrollo se distinguen las etapas de planificación, implementación, evaluación y realimentación, para identificar aspectos susceptibles de mejora. En esta contribución presentamos el trabajo desarrollado en los dos últimos cursos en la asignatura Teoría de la Comunicación (materia de Comunicaciones Digitales), Grado en Ingeniería Telemática, de la Universitat de València. Concretamente, se incorporan dispositivos de radio definida por software en los laboratorios como herramienta para conseguir unas prácticas más realistas. El artículo describe el proceso de adaptación de una sesión de laboratorio, que inicialmente fue desarrollada por un grupo piloto reducido en el curso 2018-2019, para un grupo experimental de laboratorio en el curso 2019-2020. Para evaluar el impacto de la innovación se cuantifica la implicación del alumnado, comparando los resultados del grupo experimental con respecto a dos grupos de control que han continuado con las sesiones simuladas estándar. Los resultados indican que el impacto ha sido positivo en la capacidad de los estudiantes para afrontar nuevos retos y en su percepción de la relevancia de las actividades que realizan, aunque esta mejora no se refleje en su capacidad de centrarse en ellas.Educational innovation is a process that extends beyond an academic year. In its development, the stages of planning, implementation, evaluation and feedback are distinguished in order to identify aspects that could be improved. In this contribution, we present the work developed over the last two years in the subject Communication Theory (Digital Communications), Degree in Telematic Engineering, from the University of Valencia. Specifically, software defined radio devices have been incorporated in the laboratories as a tool to bring students closer to more realistic practices. The paper describes the adaptation process of a laboratory session, which was initially developed by a small pilot group in the academic year 2018-2019, for an experimental laboratory group in the academic year 2019-2020. In order to evaluate the impact of the innovation, the involvement of the students is quantified, comparing the results of the experimental group with two control groups that have continued with the standard simulated sessions. The results indicate that the impact has been positive on the students’ ability to face new challenges and on their perception of the relevance of the activities they carry out, although this improvement is not reflected in their ability to focus on the

Evaluación del impacto del uso de dispositivos de radio definida por software como herramienta docente en la materia de comunicaciones digitales

La innovación educativa es un proceso que se extiende más allá de un año académico. En su desarrollo se distinguen las etapas de planificación, implementación, evaluación y retroalimentación para identificar los aspectos susceptibles de mejora. En esta contribución, presentamos un procedimiento para evaluar el impacto del uso de dispositivos de radio definidos por software en los laboratorios de comunicaciones digitales. Este procedimiento evalúa el compromiso de los estudiantes, además se implementan sesiones de laboratorio más realistas que se acercan a los sistemas de comunicaciones actuales y se alejan de las prácticas de simulación estándar. Se cuantifica el compromiso de los estudiantes, comparando los resultados de un grupo experimental con dos grupos de control que han continuado con las sesiones simuladas estándar. Los resultados indican que el impacto ha sido positivo en la capacidad de los alumnos para afrontar nuevos retos y en su percepción de la relevancia de las actividades que realizan, aunque esta mejora no se refleja en su capacidad de concentración.UV-SFPIE PID19-1097673Educational innovation is a process that extends beyond an academic year. In its development, the stages of planning, implementation, evaluation and feedback are distinguished in order to identify aspects that could be improved. In this contribution, we present a procedure for evaluating the impact of the use of software-defined radio devices in digital communications laboratories. This procedure evaluates the students' engagement, following more realistic laboratory sessions that are closer to current communications systems and far from standard simulation practices. The engagement of the students is quantified, comparing the results of an experimental group with two control groups that have continued with the standard simulated sessions. The results indicate that the impact has been positive on the students' ability to face new challenges and on their perception of the relevance of the activities they carry out, although this improvement is not reflected in their ability to focus on them