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Reconfigurable periodic structures for beam steering applications.


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Amiri, Reza (2017). Reconfigurable periodic structures for beam steering applications. Mémoire. Québec, Université du Québec, Institut national de la recherche scientifique, Maîtrise en télécommunications, 110 p.

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In this thesis, I study the reconfigurable meta-material structures and their applications in the field of antennas and microwave devices in both microwave and millimeter waves. This thesis is written with a paper-based strategy, and the organization of the thesis is as follows. Chapter 1 is an introduction to meta-materials, their history and their antenna applications in the literature. Chapter 2 is based on the paper, “Reconfigurable Meta-material Unit-cell with Controllable Refractive Index" by R. Amiri, B. Zarghooni, A. Dadgarpour, Pourahmadazar, J and T.A. Denidni. This Chapter presents a new meta-material unit cell with a potential reconfigurable geometry that can provide a controllable refractive index in the frequency range of 1-4 GHz. I have presented a proof of concept design where instead of the real PIN-diodes open circuits (for the OFF state) and metallic strips (for the ON state) are used. This design is simulated in HFSS, and the resulting S-parameters are utilized in a well-known extraction algorithm (explained in Appendix A) to calculate the refractive index. The presented topology is capable of providing a difference of Δn=1.5 at the frequency of 2.45 GHz which is useful for future advanced beam-tilting applications. The focus of Chapter 3 is on a unit-cell designed in the millimeter-wave frequency range. This Chapter is based on the paper "Anisotropic Meta-material Unit-cell for Millimeter-Wave Applications" by R. Amiri, B. Zarghooni, J. Pourahmadazad, A. Dadgarpour and T. A. Denidni. The unit-cell that I presented in this Chapter does not use reconfigurable elements such as PIN-diodes. Instead, it utilizes four S-shaped metallic strips to provide an anisotropic structure that can show two different refractive indexes if the direction of the arrival wave changes. This unit-cell is simulated using HFSS, and the corresponding S-parameters are utilized in the Kramer-Kronig algorithm to extract the refractive index. According to the results, if the electromagnetic wave arrives from a certain direction, it can produce a maximum difference of Δ n=2.5 in the refractive index of the structure compared to the case where the wave arrives from the transverse direction. At the end of this Chapter, a potential scenario is qualitatively explained where this property of the unit-cell can be useful in beam switching applications. Chapter 4, explains the fabrication and validation procedure of two paraffin-based dielectric lenses that are essential for the measurement of the S-parameters of meta-material unit cells. A molding process is used to fabricate these lenses, and a well-known SRR (Split Ring Resonator) design is used to test them. The SRR unit cell is fabricated in three different frequency bands, and according to our results, the lens is effective up to 15 GHz. Finally, Chapter 5 concludes the thesis and explains the summary as well as the link between each research topic with more details. This Chapter also provides the future work based on the investigations that are conducted in this thesis.

Type de document: Thèse Mémoire
Directeur de mémoire/thèse: O'Shaughnessy, Douglas
Mots-clés libres: reconfigurable meta-material structures;antennas and microwave devices;microwave and millimeter waves;Controllable Refractive Index
Centre: Centre Énergie Matériaux Télécommunications
Date de dépôt: 27 nov. 2017 21:31
Dernière modification: 27 nov. 2017 21:31
URI: https://espace.inrs.ca/id/eprint/6511

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