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Title: Multifunction dielectric resonator and microstrip antennas
Other Titles: Duo yong tu jie zhi xie zhen qi tian xian he wei dai tian xian
Authors: Lim, Eng Hock (林影福)
Department: Dept. of Electronic Engineering
Degree: Doctor of Philosophy
Issue Date: 2007
Publisher: City University of Hong Kong
Subjects: Dielectric resonators
Microwave antennas
Notes: CityU Call Number: TK7871.67.M53 L55 2007
Includes bibliographical references (leaves 113-123)
Thesis (Ph.D.)--City University of Hong Kong, 2007
v, 124 leaves : ill. ; 30 cm.
Type: Thesis
Abstract: Today, it is a trend to bundle multiple components into a single module for compact and multifunctional wireless communication systems. The concept of multifunction has been extensively applied to miniaturize RF modules. Since dielectric has been widely used as the packaging material, it spurs the interest to explore the multifunction of the dielectric resonator (DR) antenna (DRA). The DRA has many advantages such as its small size, low cost, light weight, reasonable bandwidth, and ease of excitation. It also has the advantages of having no conductive and surface wave losses. In this dissertation, different active and passive multifunction DRAs and microstrip antennas are presented for the first time. The work can be divided into four parts. They include the multifunction features such as packaging cover, oscillating load, and filtering device. In the first part, the dual functions of the rectangular hollow DRA as an antenna and a packaging cover are investigated. A low noise amplifier is integrated successfully into the embedded cavity of a rectangular hollow DR to form an active DRA. The proposed new active dualfunction DRA can achieve a much smaller size, as compared to the conventional transceivers, where the active and passive devices are normally encapsulated inside a stand alone metallic cover external to the antenna. Another distinct advantage of the proposed DRA is that having the transceiver circuits close to the antenna can greatly reduce the noise coupling into the signal paths. As for the second part, the idea of using the dielectric DRA as an oscillator load, named as DRAO, is presented. Unlike the conventional dielectric resonator oscillator (DRO), where the DR was merely used as a resonator, the DR here serves as both the radiating and oscillating loads. In addition, a compact tri-function hollow DR that incorporates the packaging function to the above dual function is demonstrated. It is shown that the loaded QL factor of the DRA can be increased by internally embedding a compact metallic cavity to the DR. It is found that with a higher loaded QL factor, the phase noise of the antenna oscillator using the hollow DRA (tri-function DRAO) is better than that using a solid DRA (dual-function DRAO). In the following part, the DRA is simultaneously used as a filtering device for the first time, named as the DRA filter (DRAF). The theory and design methodology of the DRAF are elucidated using the cylindrical DR. It was found that the operating frequency of the filter part can be made equal to, or different from, that of the antenna part. To improve the insertion loss of the filter part, the DR is top-loaded by a metallic disk without significantly affecting the radiation efficiency of the antenna part. The disk, in addition, can be used to tune the frequency of the filter. It was found that the antenna and filter parts of the DRAF can be designed and tuned almost independently. A second-order DRAF is also proposed. Finally, the microstrip and slot resonators are closely packed onto a single substrate to form the three-port integrated-antenna-filter (IAF) module. The theory and the design methodology of the IAF modules are elucidated using different microstrip/slot antennas and filters. It was found that the coupling between the antenna and filter can be easily minimized. In addition, an ultrawide-band IAF is also proposed, showing a good performance in the frequency range 3.3 – 10GHz. The characteristics of the proposed architectures were investigated using the commercial software HFSS, and measurements were carried out to verify the simulations. As the multifunction antennas are compact and cost effective, they should find applications in modern wireless communication systems.
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