Reconfigurable Beam Switching Disc Antenna Operating at 5.8 GHz

• Main Authors: Chang Fu-Hsiang, 張富翔
• Other Authors: 鄭瑞清
• Format: Others
• Online Access: http://ndltd.ncl.edu.tw/handle/f3pm25

碩士 === 國立臺北科技大學 === 電子工程系研究所 === 104 === In this thesis, a reconfigurable beam-switching disk antenna is proposed. The structure of the antenna is composed of two metallic disks, one on top and the other on bottom. The antenna is fed at the center of the disk. At a distance of one-half wavelength from the center, metallic posts are added between the two disks every 20 degree interval. Diode switches are used to connect the posts to the bottom disk such that the posts can be switched on or off individually. The basic idea of the design is to use the locations of the on-state diodes to achieve horizontal beam-switching in eighteen directions. By changing the number of on-state diodes, the front-to-back ratio can also be adjusted. In order to concentrate the radiated power to horizontal plane such that antenna gain can be enhanced, two metallic skirt structures are added to the top and bottom disks. Finally, at the back of the bottom disk, DC bias circuit is added to control the on-off states of the diodes. The design goal of the antenna is too achieve a maximum antenna gain of 8 dBi and front-to-back ratio 10 dB. The simulated return loss, maximum antenna gain and front-to-back ratio at the center frequency are -14.27 dB, 8.77 dBi and 9.75 dB, respectively. The measured return loss at the center frequency is -10.99 dB. The maximum antenna gains ranges from 6.81 to 7.85 dBi on horizontal plane and 5.10 to 7.64 dBi on vertical plane when the mainbeam is switched in four directions. The corresponding front-to-back ratios on horizontal and vertical planes range from 1.41 to 2.77 dB and 5.94 to 16.3 dB, respectively. The simulated and measured results indicate that the horizontal beam-switching effect is successfully implemented.