Low-profile planar ring-shaped monopole antenna

• Main Authors: Liu, Ching-Wen, 劉景文
• Other Authors: Sze, Jia-Yi
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/45584013235079201303

碩士 === 國防大學中正理工學院 === 電子工程研究所 === 91 === In this thesis, several designs of low-profile monopole antennas with omni-directional patterns, multiple operating bands for some special standards or specifications, and a reduced antenna height are presented. The proposed antennas with a largely lowered antenna height are basically constructed by a metallic strip composed of a straight-line section and a ring-shaped section with a tail-slit of 0.5 mm width. Dual-band or tri-band planar monopole antennas are achieved by adding one or two ring-shaped metallic strip(s) with a tail-slit in the inner space of a metallic strip with the same shape and different radii. The total length of each metallic strip, associated with the quarter wavelength of a resonant frequency excited by the metallic strip, can be calculated in the beginning of antenna design process. And, by embedding a suitably selected chip resistor at an appropriate place among ring-shaped metallic strips or adding a properly designed outer arc-shaped metallic strip, impedance matching and bandwidth enhancement of some band mismatched when the chip resistor or the outer arc-shaped metallic strip is absent can be simultaneously obtained. Thus, novel antenna designs for multi-band operation, which are the combinations between GSM and DCS, PCS bands or that between ISM and UNII bands, can be easily implemented.