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Title: A novel compact microstrip type composite right/left handed transmission line (CRLH TL) and its applications
Other Titles: Xin de jie gou jin mi wei dai xing fu he you/zuo shou chuan shu xian ji qi ying yong
Authors: Wong, Man Fai (黃文輝)
Department: Department of Electronic Engineering
Degree: Master of Philosophy
Issue Date: 2009
Publisher: City University of Hong Kong
Subjects: Strip transmission lines.
Microwave transmission lines.
Notes: CityU Call Number: TK7876 .W66 2009
ix, 84 leaves : ill. 30 cm.
Thesis (M.Phil.)--City University of Hong Kong, 2009.
Includes bibliographical references.
Type: thesis
Abstract: In recent years, research studies on the subject of metamaterials (MTMs) have increased immensely. Owing to the latent ability of metamaterials to engineer the electromagnetic and optical properties of materials for variety of applications, the impact of metamaterials can therefore be tremendous if one can manipulate the wave properties, such as the significant decreases in the size of components, devices and systems along with enhancements in their performance or special functionality appearing to be realizable. Metamaterials are, indeed, not the usual existing genuine materials. Frankly speaking, there has not been a well-fit definition for metamaterials so far; however, it can be somehow defined as artificially engineered structures with unusual electromagnetic properties. Over and above, due to the marvelous property of negative permittivity ε and permeability μ (negative refraction index), left-handed (LH) structures have undoubtedly been the most popular among the metamaterials. Based on such unique feature, numerous RF/microwave devices have been developed, including dual-band operation, bandwidth enhancement and antennas with characteristics. In this research study, a novel compact planar type of LH structure which uses metallic via-walls and stub inductors is introduced. This novel structure has the main advantage of compact dimensions and simple architecture when compared with the conventional ones. The dispersion relations are analyzed by using the equivalent circuit modeling and Bloch-Floquet theory. This novel LH structure provides the LH frequency band from 4.25 GHz to 5.65 GHz. In addition, by using this novel LH structure, a backfire-to-endfire leaky-wave (LW) antenna without any complex feeding networks is designed. Conventional leaky-wave antennas are restricted to forward direction due to the strictly positive phase constant β. However, LH LW antenna can achieve broadside radiation and continuous scanning capability as frequency is increased. For the proposed thirty unit-cell Composite Right-Left-Handed (CRLH) LW antenna, continuous backfire-to-endfire scanning is achieved from 4.5 GHz to 7 GHz with the range of scanned angle θB from -75◦ to +60◦. The comparison of full-wave simulated and experimental results is presented as well.
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