| This thesis mainly focuses on the design of antenna for portable devices. In recent years, with rapid development of mobile communication technologies and wide spreading of wireless communication networks, the demand for antennas used in portable devices (portable computer, mobile phone) with minimization and multiband has been extremely strong. How to design minimized and multiband internal antennas which work in certain circumstances is a hot topic nowadays. Slot antennas, inverted L antennas, inverted F antennas and planar inverted F antennas have been widely used in various portable devices. Slot antenna is conformal. This kind of antenna could be fed by microstrip on the back and coaxial cable with its central conductor and outer conductor connected to both sides of the slot, which provide diversities for antenna designs. Inverted L antenna and inverted F antenna have the merits of minimization and multiband, while the design theory for Planar inverted F antenna has been greatly improved.The work for this thesis could be summarized as follows:1. Wireless communication networks and development for mobile communication have been introduced briefly. Recent research and development of ILA, IFA, slot antenna and PIFA are presented.2. The performance indexes for antenna have been presented briefly, such as diversity and radiation efficiency.3. The numerical methods for antenna analysis are introduced, i.e. FDTD, MOM and FEM.4. The basic structures and operation principles for ILA, IFA and slot antenna have been introduced.5. Six minimized and multiband antennas have been designed for portable computers. For the ultra-thin portable computers, three internal inverted F antennas (Bluetooth/WiMAX/WLAN, Bluetooth/WLAN and GSM/PCS/UMTS) have been proposed. The software CST is used to simulate and investigate the three antennas. For the portable computers with metal covers, one slot antenna (Bluetooth/WLAN) fed by microstrip on the back and another slot antenna (Bluetooth/WLAN) fed by coaxial cable are proposed. Simulated and measured results for both slot antennas are presented. Meanwhile, an investigation about further minimization on the slot antenna fed by coaxial cable has been made. |
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