| Summary: | 碩士 === 國立交通大學 === 電信工程系所 === 97 === With the development of the wireless communication, more and more devices share the limited bandwidth for communication. Therefore, how to reduce the interference from other devices and environment and use the limited bandwidth efficiently is one of the important subjects. A smart antenna which can change radiation patterns and focus the patterns is a good candidate to solve those problems.
In this thesis, a novel dual-band smart antenna is developed. By the switching frequency selective surface, the principle of a right angle corner reflector antenna, and the operation of switches, three dual-band pattern reconfigurable antennas are investigated. The operating frequencies in our design are 2.45 GHz and 5.25 GHz. Through combinations of switches on reflecting walls, multiple radiation patterns can be obtained.
Each reflecting wall of the first proposed pattern reconfigurable antenna operates only at one frequency; therefore, Two-layer reflecting walls are needed here. However, the volume of the completed antenna is about one-wavelength of 2.45 GHz square due to the principle of the corner reflector antenna. In the second proposed antenna, a reflecting wall can operate at two frequencies. As a result, the size of the antenna can be reduced, and the amount of switches can be decreased too. Finally, a dual-band pattern reconfigurable antenna with a simpler structure such as a rectangular loop is developed without the damages to the original properties belonging to the second antenna. Since omni-directional and directional patterns are the most important in application, we mostly focus on those two patterns in our design.
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