Design of asymmetric coplanar strip folded dipole 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: 2014

Öğrenci: KAMİL KARACİĞER

Danışman: LALE ALATAN

Özet:

This thesis includes the design, simulation, production and measurement of an asymmetric coplanar strip folded dipole antenna suitable to be used as an element in a linear array operating at S-band (2.7 GHz - 3.3 GHz). In this same manner, its usefulness as an array antenna is also explored in this thesis. This antenna element consists of a microstrip line feed, microstrip to coplanar stripline transition (BALUN) and asymmetric coplanar strip (ACPS) folded dipole. The planar folded dipole can be constructed using printed circuit technology, its input impedance can be adjusted over a wide range of values, and it has significantly greater bandwidth than a single half-wave dipole and conventional patch radiators. These properties make planar folded dipole antennas an appealing choice as a radiating element. A step-by-step procedure is followed during the design process of the ACPS folded dipole antenna element. The design process is based on the simple impedance matching among antenna element components, i.e. feed, transition, and antenna. First, BALUN which consists of microstrip feed line and microstrip to coplanar stripline transition is designed and simulated using Ansys HFSS®, a high frequency vi electromagnetic field simulation program. Then, in order to investigate the effects of ACPS folded dipole parameters on the input impedance characteristics of the antenna, a parametric study is performed using Ansys HFSS®. By the help of the experience gained through these parametric analyses, an ACPS folded dipole is designed and simulated. Once the ACPS folded dipole is connected to the balun, the design of antenna element is completed. Before manufacturing the antenna element, the complete structure is simulated and optimized with Ansys HFSS® to achieve a good matching over the operating frequency range. Additionally, a linear array antenna comprising four asymmetric coplanar strip folded dipole antenna elements and a suitable power divider network to feed the array are designed and simulated. Finally, the antenna element and the four-element uniform linear array antenna are manufactured, measured, and their performances are compared with simulation results.