Near Field Probe Correction using Least Squares Filtering Algorithm

International audienceThe deconvolution technique is widely used for probe correction in the near field technique measurement. However, the measurement noise makes the result obtained by this method inefficient and requires the use of a very low noise measurement facility. In this paper, we present a method to improve the probe correction accuracy by an inverse filtering approach that takes into account the statistical characteristics of the measurement noise using the constrained least squares filtering algorithm (CLSF). Computations with EM software data of two different structures illustrate the reliability of the method

A novel methodology for time-domain characterization of a full anechoic chamber for antennas measurements and exposure evaluation

In this paper we present a novel methodology for time-domain characterization of a full anechoic chamber using the finite integral method. This approach is considered fast, accurate and not intensive for computer resources. The validation of this approach is carried out on CST-microwave studio for a full anechoic chamber intended for antennas measurement applications and electromagnetic exposure evaluation for cellular network. Low, medium and high gain sources are used in this study. The simulations are realized on a personal computer of medium performances (i7 CPU and 16 GB of RAM). The stability and the convergence of our approach are obtained thanks to local mesh and auto-regressive linear filtering techniques. The minimization of the simulation time is based on use of the Huygens sources in the place of the antennas. The maximum error of the chamber as well as the wave depolarization into the chamber are at one with the previous work and the catalogs of the principles chambers manufacturers for the proposed tests in this paper. The Full simulations time is about 15 hours in average

Measurement methodologies for reducing errors in the assessment of EMF by exposimeter

Objective: As well known, using a single body worn sensor exposimeter introduces systematic errors on the measurement of the incident free space electric field strength. This is because the body creates around it high, intermediate and low level field zones, which depend on the direction of arrival of the incident field. The goal of this work is to propose an efficient method for the reduction of these errors. Methods: After classifying the perturbations induced by the body on the measured electric and magnetic fields thanks to realistic numerical simulations, we then propose a two-sensor setup in conjunction with simple semi-empirical correction formulas, in order to compensate these perturbations. Results: At 942 MHz, when the two sensors are placed in any opposite sides of the body at chest height, the worst case, maximum and average errors respectively decrease to 12% and 3% compared to 83% and 22% for measurement techniques using a single sensor, or 32% and 11% when using the average value of the measurements. Conclusion: The error related to the measurement in the presence of the body was significantly reduced by the proposed method making use of two opposite sensors, E-field and H-field at the chest. Significance: The conformity of exposure to EMF in terms of reference values according to the ICNIRP is given in the abscence of the human body. The interest of this work lies in the reduction of the errors made when measuring the field in the presence of the body

Didactic Simulations for Electromagnetism Based on an Element Oriented Model

The web has spurred our imagination as to how education can be drastically transformed and improved through the adoption of Information and Communications Technology (ICT) and the use of simulations quickly became a wildly disputed topic. This kind of simulations are considered as a significant pedagogical innovation especially in the electromagnetics course where it is possible to concretize , via a set of interactive simulations, some experiments that are inaccessible in real life. The aim of interactive simulations is to enhance the student’s understanding by providing him a meaningful insight into the studied notions, phenomena, concepts, laws and models. The design of didactic simulations is constrained by both technological choices, learning theories and numerical models which should guarantee a minimal execution time, a better stability and an acceptable precision. Our goal in this work is to design didactic simulations for electromagnetism using a numerical Element Oriented Method (EOM). The proposed EOM meets the needs of speed, accuracy and ensure bet-ter dynamical and visual interpretations of the basic laws of electromagnetic. Moreover, these applications are not only available for traditional training in the classroom but also for new training platforms provided by digital technologies such as web-based training, e-learning and m-learning

Basic Concepts of a Phase-Locked Loop Control System

Phase-locked loop (PLL) is one of the main components ofmodern electronic design and has been around for a considerable numberof years. It is a technique that has greatly contributed to the technological advancement of communications and control systems. This paperpresents a phase-locked loop tutorial based on a control system, it givesa concise review of basic concepts, the different types of PLLs, linearanalysis approaches of analog systems PLL is discussed, furthermore thetheoretical analysis of the steady-state error in detail is presented, and itssimulations of different phase offset values in C program are presented,and show how the response of the loop changes

Didactic Simulations for Electromagnetism Based on an Element Oriented Model

The web has spurred our imagination as to how education can be drastically transformed and improved through the adoption of Information and Communications Technology (ICT) and the use of simulations quickly became a wildly disputed topic. This kind of simulations are considered as a significant pedagogical innovation especially in the electromagnetics course where it is possible to concretize , via a set of interactive simulations, some experiments that are inaccessible in real life. The aim of interactive simulations is to enhance the student’s understanding by providing him a meaningful insight into the studied notions, phenomena, concepts, laws and models. The design of didactic simulations is constrained by both technological choices, learning theories and numerical models which should guarantee a minimal execution time, a better stability and an acceptable precision. Our goal in this work is to design didactic simulations for electromagnetism using a numerical Element Oriented Method (EOM). The proposed EOM meets the needs of speed, accuracy and ensure bet-ter dynamical and visual interpretations of the basic laws of electromagnetic. Moreover, these applications are not only available for traditional training in the classroom but also for new training platforms provided by digital technologies such as web-based training, e-learning and m-learning

On Calibration of Correction Law for EMF Measurement Errors due to the proximity of the human body

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Caractérisation planaire du champ proche appliquée aux dispositifs numériques et radiofréquences

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A Novel Expert Evaluation Methodology Based on Fuzzy Logic

In order to maintain the training quality and ensure efficient learning, the introduction of a scalable and well-adapted evaluation system is essential. An adequate evaluation system will positively involve students in the evaluation of their own learning, as well as providing teachers with indicators on the student's strengths, the specific encountered difficulties and the false or misunderstood studied parts. In this context, we present, in this article, a novel intelligent evaluation methodology based on fuzzy logic and knowledge based expert systems. The principle of this methodology is to reify abstract concepts of a human expertise in a numerical inference engine applied to evaluation. It reproduces, therefore, the cognitive mechanisms of evaluation experts. An im-plementation example is presented to compare this method with the classical one and draw conclusions about its efficiency. Furthermore, thanks to its flexibility, different kinds of extensions are possible by updating the basic rules and adjusting to possible new architectures and new types of evaluation

Characterisation of planar near-field applied to digital and radiofrequency systems

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