An optimization design method of circularly?polarized antenna is presented for the globally?universal ultrahigh fre?quency(UHF)RFID reader?writer terminal. On the basis of the traditional broadband stacked microstrip antenna,the axial ra?tio bandwidth of the antenna is broadened by loading the center short circuit column,and improving the T?type dual?feed power?dividing and phase?shifting network. The impedance bandwidth of the antenna is further broadened by means of the matching tuning stub. The design thought of the antenna is given,and its electromagnetic simulation optimization is performed. The fabri?cating test was carried out for the antenna. The test results show that,within 840~960 MHz frequency band,the antenna standing wave ratio is less than 1.5,its axial ratio is less than 3 dB,and the gain can reach up to 9 dB. The designed antenna has been successfully applied in the ultrahigh frequency four?channel reader?writer terminal.%提出一种全球通用超高频RFID读写器终端圆极化天线的优化设计方法.在传统叠层微带天线宽带化的基础上,通过加载中心短路柱和改进T型双馈电功分移相网络扩展天线的轴比带宽,并利用匹配调谐片进一步展宽天线的阻抗带宽,给出天线的设计思路,并进行了电磁仿真优化.最后对天线进行加工试验,测试结果表明在840~960 MHz频带范围内,天线驻波比小于1.5,轴比小于3 dB,增益可达9 dB.所设计的天线已成功应用于超高频四通道读写器终端.
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