Reconfigurable Patch Antennas with Omni-Directional Radiation

• Main Authors: Ming-Che Chan, 詹明哲
• Other Authors: Jeen-Sheen Row
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/83266671360237422832

碩士 === 國立彰化師範大學 === 電機工程學系 === 97 === Designs of frequency and polarization reconfigurable microstrip patch antennas with conical radiation are respectively presented in this thesis. For the reconfigurable frequency antenna design, a monopolar patch antenna structure is used to generate conical radiation patterns. The frequency switching is realized by controlling four diodes to reconfigure the size of the shorted rectangular patch of the monopolar patch antenna. Each diode connects one side of the shorted rectangular patch and an open stub. For the reconfigurable polarization antenna design, the used antenna structure is single feed and involves two resonant modes, in which a 4-element-array loop antenna mode, producing horizontal polarization, and a monopolar patch antenna mode, producing vertical polarization. By properly exciting and coupling the two resonant modes, circular polarization radiation can be obtained. Moreover, the polarization switching is achieved by controlling four diodes to reconfigure the number of the shorting walls. Two prototypes for the abovementioned reconfigurable frequency and polarization antennas are implemented, respectively, and their dimensions are obtained by numerical analyzing with HFSS. From the measured results, the operating frequency of the reconfigurable frequency antenna has a tunable range from 1820 ~ 2480 MHz, and good omni-directional radiation patterns are observed across the available operating frequencies. As for the reconfigurable polarization antenna, the measured results exhibit the antenna prototype has the ability of switching polarization, and the operating frequencies of the right-hand and left-hand circular polarization occur at 2900 and 2420 MHz, respectively. Also, both the operating frequencies have a return loss of less than 10 dB and an axial ratio of less than 3 dB.