Aller au menu Aller au contenu
Microelectronics, electromagnetism, photonics , microwave

> Events > PhD-Defenses

PhD defense of NIMISHA SIVARAMAN

Published on November 8, 2017
A+Augmenter la taille du texteA-Réduire la taille du texteImprimer le documentTélécharger au format PDFEnvoyer cette page par mail Partagez cet article Facebook Twitter Linked In Google+ Viadeo
PhD Defense December 5, 2017 | Access map
Thesis defense of NIMISHA SIVARAMAN , for a doctoral thesis of the University of Grenoble Alpes, speciality "OPTICS & RADIOFREQUENCY  ", entitled:
Amphi  Z108 (Bâtiment Z 1st floor) - Phelma/Minatec
3 rue parvis Louis Néel
38016 Grenoble cedex1

« Design of printed circuit magnetic probes for near field measurements and the development of algorithms for the prediction of EMC »

Nimisha SIVARAMAN

Nimisha SIVARAMAN

Tuesday, December 5th,  2017 at 10:30

Abstract:
As the number of components in a confined volume is increasing, there is a strong demand for identifying the sources of radiation in PCBs and the prediction of EMC of electronic circuits.   Electromagnetic near field scanning is a general method of identifying the radiating sources in a PCB.  The first part of the thesis consists of the design and characterization of printed circuit magnetic probes with high sensitivity and high spatial resolution. Conventional probes based on microstrip and coplanar configuration is studied.  As the length of the transmission line connected to the probe increases, the probe output contains noise due to common mode voltages which is many induced by the electric field.  In order to suppress the voltage induced due to the electric field, a shielded magnetic probe is designed and fabricated using low cost printed circuit board (PCB) technology. The performance of the passive probe is calibrated and validated   from 1MHz – 1GHz.  The shielded probe is fabricated on an FR4 substrate of thickness 0.8mm and consists of 3 layers with the signal in the middle layer and top and bottom layers dedicated to ground planes. The aperture size of the loop is 800µm x 800µm, with an expected spatial resolution of 400 µm.  The high sensitivity of the probe is achieved by integrating a low noise amplifier at the output of the probe, hence making an active probe. The performance of the shielded probe with different length of transmission lines is made to study. When the probe has to be operated above 100MHz, it is found that the transmission lines connected to the probe should be short (around 1.5cmm). For frequencies below 100MH, the length of the lines can be up to 12cm.   A three axis probe which is able to measure the three components of the magnetic field are also designed and validated by near field scanning above a standard wire over ground structure.
In The second part, the inverse transmission line matrix method (Inv-TLM) method is used reconstruct the source distribution from the near field scan (NFS) data above a single in plane on the PCB.   Even though, the resolution of reconstruction depends on the wavelength and the mesh parameter, the inverse propagation increases the width of the reconstructed wave.  As this method is found to be  ill posed and results in multiple solutions, we have developed a new method based on the two dimensional cross correlation, which represents the near field scan data in terms of the equivalent electric currents of dipole. With the new method, we are able to identify and locate the current sources in the PCB, and is represented with an equivalent source. The method is validated for the current sources with different orientations. The simulated near field data using CST microwave studio is used to validate both the methods. The radiated far field from these equivalent sources is compared with the simulated fields.  The amplitude and phase of the reconstructed equivalent source is a key factor which determines the radiated far field and errors in the predicted field are possible if the amplitude and phase are not correct. With the equivalent dipole electric current, all the sources are represented with positive amplitude. Representation in terms of the equivalent current of magnetic dipole will be more accurate method for PCBs involving many current loops.   
 
Members of  jury :
  • Fabien NDAGIJIMANA - Supervisor
  • Daniela DRAGOMIRESCU - Rapporteur
  • Eduardo MOTTA CRUZ - Rapporteur
  • Sébastien SERPAUD - Examiner
  • Christian VOLLAIRE - Examiner
  • MUTEL LEONCE - Examiner

A+Augmenter la taille du texteA-Réduire la taille du texteImprimer le documentTélécharger au format PDFEnvoyer cette page par mail Partagez cet article Facebook Twitter Linked In Google+ Viadeo

Partenaires

Thesis prepared in the laboratory : UMR 5130 - IMEP-LAHC  , supervised by Fabien NDAGIJIMANA.

Written by Brigitte Rasolofoniaina

Date of update November 8, 2017

Contact

M. Fabien NDAGIJIMANA
Envoyer un mail
français
IMEP-LAHC
Grenoble site
Grenoble INP - Minatec : 3, Parvis Louis Néel - CS 50257 - 38016 Grenoble Cedex 1

Chambéry site
Université de Savoie - F73376 Le Bourget du Lac Cedex
 


  CNRS  http://www.cnrs.fr      Site Grenoble-INP http://www.grenoble-inp.fr       Université Grenoble Alpes (UGA)      Université Savoie Mont Blanc
Univ. Grenoble Alpes