Reconfigurable Array Antenna Designs

• Main Authors: Chien-Ting Huang, 黃健庭
• Other Authors: 羅鈞壎
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/03495208363283787908

碩士 === 國立彰化師範大學 === 電機工程學系 === 98 === Reconfigurable designs for array antennas with switchable polarization and radiation pattern are respectively studied in the thesis. The studies are divided into three parts. Chapter I describes the design of an omnidirectional array antenna with switchable polarization. By controlling the states of PIN diodes, the polarization of each array element can be switched between linear and circular polarizations; in addition, the omnidirectional radiation patterns are generated with the arrangement of a 2 × 2 array. An example operated at the WLAN band (2400 ~ 2480 MHz) is realized, and the measured results indicate that the design not only can provide three polarizations, including dual orthogonal linear polarizations and one circular polarization, but also can give uniform conical beams. In Chapter II, a novel reconfigurable phase feeding network is first proposed and analyzed. The phase network is composed of two parallel coupled lines and capacitors. By properly selecting the capacitance values of the capacitors, two output ports of the phase network can be with the same phase and the 90° phase differences. Comparing to the Butler Matrix phase network, the size of the proposed phase feeding network is reduced by 1.8 % and the transmission loss is decreased by 1 dB. An integrated design for circular-polarized antennas with beam steerable is presented in chapter III. The reconfigurable phase feeding network given in chapter II is used to control the exciting phase of each element of a 2 × 2 array antenna. When the phase of each element is changed, the main beam direction of the array can be switched between 0° and 25°. Another microstrip array consisting of four rectangular patches and shorting posts are also integrated to the 2 × 2 array antenna. The microstrip array can also radiate a conical beam whose maximum occurs at 35°. Experiment results demonstrate that the pattern reconfigurable antenna can maintain the return loss less than 10 dB and the axial ratio lower than 3 dB as the main beam is switched. Keywords: reconfigurable array antenna, polarization diversity, pattern diversity, phase network