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Antennes aux ondes millimétriques avec faisceau incliné en utilisant des structures métamatériaux.

Dadgarpour, Abdolmehdi (2015). Antennes aux ondes millimétriques avec faisceau incliné en utilisant des structures métamatériaux. Thèse. Québec, Université du Québec, Institut national de la recherche scientifique, Doctorat en télécommunications, 218 p.

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The ISM frequency band at 60 GHz (57-64 GHz) has attracted much attention for its large frequency bandwidth (7 GHz). This band enables multi Gb/s data rate transmission and enhanced immunity as well as frequency re-use. However, due to the atmospheric absorption loss at this band the propagated signal degrades considerably. This issue can be compensated by using high-gain antennas. Beam alignment is another challenge for high gain antennas where the location of transmitter or receiver is not fixed. This is due to narrow beamwidth of such antennas. The solution to resolve this issue is using beam switching or beam scanning networks such as phased antenna arrays. Existing beamforming systems based on phased antenna array incur large loss and are complex to implement in practice rendering them high-cost solution. An alternate solution proposed in this thesis is to realize beam tilting using metamaterials to minimize the loss and cost issues as well as obtain a low-profile structure. In this dissertation, first and foremost, an array of meander line H-shaped resonators, which operate as an anisotropic metasurface at C-band, were integrated in front of a standard bow-tie antenna in order to tilt the direction of the antenna’s main beam in the azimuth plane. In order to tilt the antenna’s radiation beam in the elevation plane an array of inhomogeneous split-ring resonators are embedded in the H-plane of end-fire bow-tie antenna. The proposed designs are shown to provide a viable solution for next generation of base-station antennas that need to be capable of tilting the direction of the main beam under the horizon. This particularly includes 5G wireless cellular networks envisaged to operate at millimeter-waves. The proposed technique is also applicable at C-band (7-8 GHz) and WiMAX band (3.4-3.6 GHz). The high-gain antenna proposed here for operation at millimeter-wave (57-64 GHz) is based on a bow-tie configuration which is fed by surface integrated waveguide (SIW). The technique proposed here to increase the antenna gain involves (i) embedding a split-ring resonator at the back side of bow-tie antenna, (ii) tilting the bow-tie radiators with respect to the end-fire direction, and (iii) integrating an array of folded H-shaped resonators to create a region of low refractive index in front of the bow-tie radiator in order to convert the antenna’s spherical waves into planar waves. The measured results indicate that the antenna gain improves to 12 dBi over 57-64 GHz. Another technique demonstrated here to deflect the main beam of a standard dipole antenna involves incorporating in the azimuth plane of the antenna a media with gradient index of refraction. This technique enables beam switching from -58 to +58 degrees over 57-64 GHz with maximum gain of 9.5 dBi at 60 GHz. In order to obtain beam steering in the Elevation plane, the proposed folded H-shaped resonators are loaded in the E and H-plane of dipole. This arrangement is shown to provide two-dimensional beam tilting or beam switching at 60 GHz. However with this approach, the antenna gain is limited to 10 dBi and the beam deflection is limited to 17 degrees in both planes. To achieve a higher gain and tilt angle an array of split-ring resonators (SRR) were integrated in front of a quasi TE-source generated by a dipole antenna at 60 GHz. The magnetic resonance of the SRRs result in a tilt angle of 34 degrees in both the azimuth and elevation planes with maximum peak realized gain of 14 dBi over 57-64 GHz. Finally, to achieve a dual beam and broad beamwidth radiation in the azimuth plane of end-fire bow-tie antenna an array of stub-loaded H-shape resonators were integrated in front of the antenna. The measured results show beam deflection at +30 and -30 degrees with respect to the end-fire direction with the maximum peak realized gain of 9 dBi at 60 GHz.

Type de document: Thèse
Directeur de mémoire/thèse: Denidni, Tayeb A.
Mots-clés libres: antenne à inclinaison de faisceau; structure en métamatériaux; antenne à gain élevé
Centre: Centre Énergie Matériaux Télécommunications
Date de dépôt: 06 avr. 2016 20:15
Dernière modification: 06 avr. 2016 20:15
URI: http://espace.inrs.ca/id/eprint/3362

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