Theoretical investigation and design of wideband dielectric resonator antennas

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Tezin Türü: Yüksek Lisans

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

Tezin Onay Tarihi: 2015

Öğrenci: YILMAZ ÇAĞRI YÜKSEL

Danışman: LALE ALATAN

Özet:

The aim of this thesis is to utilize Dielectric Resonator Antennas (DRA) as array elements due to their advantages over other conventional antenna elements such as dipoles and microstrip patches. Depending on both the excitation mechanisms and the antenna shape, a Dielectric Resonator Antenna (DRA) provides its designer multiple independent degrees of freedom. In this thesis three antenna shapes, namely hemispherical, cylindrical and rectangular DRAs, are investigated. The cylindrical and the rectangular shaped DRAs are used in designs. A design software that calculates the initial dimensions of the DRAs is developed and these dimensions are optimized through the full-wave analysis performed by using a Finite Element Method (FEM) based electromagnetic field solver. The concept of a compact DRA with wideband operation in 2.9-3.3 GHz frequency band is presented. The return losses, impedance characteristics, internal field distributions and radiation patterns of DRA elements are discussed. The effect of dimensional parameters of both antenna element and feed network are investigated. The rectangular and stack-cylindrical shaped DRAs are manufactured and excited via microstrip slots. For rectangular DRA a -10dB impedance bandwidth of 20.3% and a gain of 5.28dB are obtained. An enhancement is achieved both in the -10dB impedance bandwidth (44.7%) and the gain of the antenna (9.35dB) with stacked-cylindrical DRA configuration. A Taylor amplitude tapered linear array is designed to achieve 10 degree half power beam width (HPBW) with 30dB side lobe level (SLL). An 8-arm modified Wilkinson unequal power divider is designed to implement a linear array with high ratios between excitation amplitudes. Array characteristics are measured in the near field antenna measurement chamber. The prototype and the test results for the antenna element and the array structure are discussed. For rectangular DRA array, 10.1dB gain, -26dB SLL and 9.60 HPBW are obtained. For stacked-cylindrical DRA configuration, 14.3dB gain, -26.9dB SLL and 9.50 HPBW are achieved.