Design and Analysis of a Wideband Feed for Metsähovi Compact Array
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Journal Title
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Volume Title
Sähkötekniikan korkeakoulu |
Master's thesis
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Authors
Date
2017-01-23
Department
Major/Subject
Communications Engineering
Mcode
ELEC3029
Degree programme
CCIS - Master’s Programme in Computer, Communication and Information Sciences (TS2013)
Language
en
Pages
56+6
Series
Abstract
Radio telescope is an astronomical instrument and an essential tool of radio astronomy. It is consists of a radio receiver and antenna system. The design of antenna system of the radio telescope is a critical issue because of the demand of wide bandwidth, high gain, directional beam, and circular polarization. Metsähovi radio observatory has proposed a project named Metsähovi compact array to build four radio telescopes in order to create new research platform in different areas, such as radio astronomy, solar research, and space physics. In this master thesis work, a wide band feed for the reflector antenna of the proposed radio telescope is analyzed and designed. Initially several solutions are studied and analyzed. Based on these studies, a two arm conical log spiral antenna (CLSA) is designed and constructed in CST. At first, a theoretical model of CLSA is developed. Further, the design equations are reformulated to simulate the model in CST. The simulation results shows good agreement with the theoretical model. Moreover, the antenna is also simulated with the bifilar lines to have an practical feeding system of the antenna. In this case the results shows poor performance due to the significant radiation coming out from the bifilar lines which is overlapping with the antenna radiation. To avoid this radiation, a hollow metal is introduced which covers the bifilar lines to block the radiation coming out from the bifilar lines. The antenna performance with bifilar lines satisfies most of the requirements that has set up for this work. Besides, a mechanical construction of the antenna is presented to protect the antenna from the outside environment.Description
Supervisor
Lähteenmäki, AnneThesis advisor
Kirves, PetriKeywords
CLSA, circular polarization, gain, HPBW, reflector antennas, radiation pattern