| Summary: | 碩士 === 亞東技術學院 === 資訊與通訊工程研究所 === 103 === The main objective of this thesis is about the design and implementation of broadband wide-beam circular polarization antenna for global navigation satellite systems (GNSS). In outer space, when linearly polarization antenna transmit signals to Earth, signal will pass through ionosphere of atmosphere, the electromagnetic waves will be affected by the ionosphere because the Faraday rotation effect, it will cause distortion because different polarization between the transmitting and receiving antenna, therefore, most of satellite positioning system antennas are designed to circular polarization.
There is three parts in this thesis, the first part is the basic theory, including power divider, characteristics and parameters of circular polarization antennas, The second part is the antenna design and implementation of research and exploring, using couple-fed to replace the traditional direct-fed to increase bandwidth, with two different forms of broadband wide-beam antenna to achieve the design goal, and then to compare measurement and simulation results to verify theory. First one is a patch antenna which is designed to multilayer with Wilkinson power divider, the middle layer is two sloping T-probes, the result of reflection coefficient from 1.15GHz to 1.6GHz are below -10dB, the efficiency is between 50% to 90%, the antenna gain is more than 5dBi and the axial ratio is below 3dB, the half power beam-width is between 55 to 90 degrees. The second one use two orthogonal electromagnetic dipole to form circular polarization, the result of reflection coefficient from 1.15GHz to 1.6GHz are below -9dB, the efficiency is between 50% to 70%, the antenna gain is more than 4dBi and the axial ratio is below 3dB, the half power beam-width is between 60 to 100 degrees. The third part is the conclusion of two antennas in this paper, organize and illustrate for the half-power beamwidth, the axial ratio and the other measure results.
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