Thesis by Ali GHADDAR

"Surface wave guidance on textile metamaterials

Thesis defence on 23 March 2022 at 10 a.m.
IEMN Amphitheatre - Central Laboratory - Villeneuve d'Ascq

Jury :

Bruno SAUVIAC, Professor, LHC, University of Saint-Etienne, Rapporteur
Florence PODEVIN, Professor, TIMA, INP Grenoble, Rapporteur
Aziz BENLARBI-DELAI, Professor, GEEPS, Sorbonne University, Examiner
Fabien FERRERO, Professor, LEAT, Université Côte d'Azur, Examiner
Éric LHEURETTE, Professor, IEMN, University of Lille, Thesis supervisor
Ludovic BURGNIES, Director, IEMN, Université du Littoral-Côte d'Opale, Co-supervisor
François RAULT, Director, GEMTEX, ENSAIT, Guest
Rose-Marie SAUVAGE, Head of AID, DGA, Guest

Summary:

The work presented in this thesis is devoted to the study of surface wave guidance on textile metamaterials based on conductive yarns. The main aim of these studies is to contribute to the development of technologies dedicated to surface waves on textiles for communication applications around the human body operating at 2.45 GHz. The existence of the surface wave is best known in the field of optics through the surface plasmon polariton that propagates naturally on the surface of metal. The surface wave is characterised by an electromagnetic field confined to the surface of the metal and by a slow propagation speed compared with the propagation speed in free space. To take advantage of these properties, the field of metamaterials makes it possible to extend this concept to low frequencies by means of a periodic arrangement of metal patterns.
The studies presented in this thesis focus on the propagation of a surface wave on corrugated or meandering lines without a ground plane, and on two-dimensional metasurfaces. The surface waves were excited in the near field by dipole antennas. Lines and metasurfaces were fabricated in PCB technology, and others on textiles using conventional manufacturing techniques widely used in the textile industry, namely embroidery and 3D spacer knitting. The performances in terms of transmission and dispersion diagram of the electromagnetic wave on the various textile structures are analysed in detail experimentally and in simulation. They are also compared with the performance of PCB structures. Meander lines and metasurfaces embroidered on a cotton textile showed good performance, with improved transmission between antennas compared with free-space transmission. The transmission performance of a meander line under curvature was also evaluated experimentally for communications around the human body.
All the work presented is based on simulation studies verified experimentally by determining dispersion curves and transmission properties.

Abstract:

The works shown in this thesis are devoted to the study of surface waves onto metamaterials produced in textiles by using a conductive yarn. The main objective of these studies is to promote technologies dedicated to surface waves guided onto textiles targeting wireless communications around the human body and operating at 2.45 GHz. The existence of a surface wave is more known
in optics by the surface plasmon polariton which propagates naturally on the surface of a metal. It is characterized by an electromagnetic field trapped onto the surface and by a slow wave propagation compared to the propagation in free space. In order to benefit from the electromagnetic confinement property, metamaterials has opened the way for the surface wave development at lower frequency by means of periodic arrangement of metallic patterns.
Studies carried out in this thesis are focused on the propagation of a surface wave guided by corrugated lines or meander-shaped lines without ground plane and by two-dimensional metasurfaces. Surface waves were excited in near field by means of dipole antennas. Some lines and metasurfaces were fabricated by Printed Circuit Board (PCB) technology and others on textiles by using conventional manufacturing techniques widely used in textile industry, namely embroidery and 3D spacer knitting. Performances in terms of transmission and dispersion curves of the electromagnetic wave propagating onto the textile structures are precisely analysed in experiments and simulation. Then, they are compared with performances of the structures fabricated by PCB. The meander-shaped lines and metasurfaces manufactured by embroidery on a cotton fabric showed good performances with an improvement of the transmission between the antennas compared to the transmission in free space. Performances of the meander-shaped line under curvatures were experimentally evaluated as well with the purpose of applications for body area communications.
All the work shown in this thesis is based on simulation studies experimentally validated by determining first the dispersion curves and second the transmission properties.