Novel multi-band metamaterials in microwave region with applications in antennas

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Tezin Türü: Doktora

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Elektrik ve Elektronik Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2014

Öğrenci: ÖZNUR KÜÇÜKSARI

Danışman: GÖNÜL SAYAN

Özet:

This dissertation is focused on the design, fabrication, and characterization of multi-band metamaterials in microwave region with novel applications in antennas with the following outcomes: In the first part of dissertation, important concepts that have to be considered during the design, simulation and characterization of planar metamaterial arrays are investigated. All investigations are performed using the planar dual band nested U-ring resonator (2-NURR) metamaterial array that is a novel exemplar of the planar metamaterial arrays. First, effects of different electromagnetic excitation types on the behavior of planar 2-NURR metamaterial array are examined. Then, the effects of using different boundary conditions and different computational volume dimensions in numerical simulations of periodic planar 2-NURR metamaterial arrays are investigated. Next, the commonly used parameter retrieval methods are reviewed with a special focus on the widely used Nicholson-Ross-Weir (NRW) algorithm. Finally, the important shortcomings of NRW algorithm are demonstrated for dense metamaterial arrays. In the second part of dissertation, the M-band nested split ring resonator (M-NSRR) having a small and geometrically simple unit cell is introduced as a novel multi-band MNG type metamaterial. Then, design and simulation procedures, fabrication and measurement processes for the M-band nested U-ring resonator (M-NURR) are given as the modified simpler version of the M-NSRR topology. Next, the single-sided and double-sided (in broadside-coupled configuration) versions of the M-NURR are demonstrated on a comparative basis for further miniaturization of the M-NURR topologies. At the end of this part, performances of nested ring resonators with different topologies are compared. In the last part of dissertation, metamaterial-inspired electrically small, single-, dual- and triple-band antennas with steerable radiation patterns and high radiation efficiencies at the GSM (1.93-1.99GHz), ISM (2.43-2.4835GHz), and WIMAX (3.3-3.6GHz) frequencies are introduced. First, performance characteristics of these single-band and multi-band antennas are investigated numerically. Then, three different single band antennas having their maximum directivities in the vertical, diagonal and horizontal directions at the GSM (1.93-1.99GHz) frequencies are fabricated as the exemplars of the antennas with steerable radiation pattern and experimental results from these antennas are reported. Finally, experimental results for fabricated dual- and triple-band antennas having their maximum directivities in the vertical directions are demonstrated as examples to multi-band metamaterial antenna applications.