| Summary: | 碩士 === 國立宜蘭大學 === 電子工程學系碩士班 === 97 === In order to meet the requirement of the rapid growth in wireless communication system, a mobile device is not only more tiny but also more powerful. Also, antennas embedded in the device requires low profile but multiband operation. Thus, how to design internal multiband antennas for mobile devices is mainly discussed in this thesis. Recently, the antenna structure used to achieve wide band operation in a narrow space is based on inverted-F type, using parasitic elements to generate multiple resonances or introducing slits to the main resonator to create multiple resonant paths. However, the couplings between each parasitic element are very strong and the resonant mechanism is quite complicated when designing a hepta-band antenna in a narrow space. Hence, four internal multiband antenna designs were proposed and presented in this thesis, two for laptop computers and two for smart phones. Arrangement of each parasitic element and analysis methods are clearly demonstrated, making the design process of the complicated multiband antenna much easier to be followed step by step. In addition, using a matching element near the feed point to match input impedance, and employing a composite loop pattern to excite four resonating modes which including a folded-dipole mode, are presented to achieve wide-band operation with low profile. These antennas that can be coated on a 0.8mm PCB substrate are simple but easily constructed. Finally, beside using simulation tool, HFSS to design, measurements were performed for each design to verify the simulation results. Good agreement confirms the measured results meet the system requirements.
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