一种新型宽带双频段圆极化RFID读写天线

提出了一种新型宽带双频圆极化射频识别(RFID)读写天线,由上层的旋转对称折合振子和缝隙加载的方形贴片以及下层的紧凑型馈电网络构成。天线具有两个外部端口,分别激励低频0.9 GHz和高频2.45 GHz双频段的圆极化辐射。借助HFSS对天线进行了建模、仿真和优化,最后采用FR4板材制作天线实物并完成了试验测试。天线的外部尺寸为0.6λ0×0.6λ0×0.1λ0(λ0为0.9 GHz频点下的自由空间波长),测试结果表明,天线在低频段和高频段的-10 dB阻抗带宽和3dB轴比带宽分别为91.1%(4.9%)和87.8%(1.3%),频段内的峰值增益为5.48 dBic(3.63 dBic),最小轴比为1.1 dB(1.2 dB),在高低频段内,天线的辐射方向图对称稳定。该天线不仅能够满足全球通用型UHF频段(0.84~0.96 GHz)和ISM频段(2.4~2.5 GHz)RFID读写应用需求,而且具有低成本、易加工等优点,在物联网领域将具有很好的应用前景。

A Novel Dual-Band Circularly Polarized Antenna with Broadband for RFID Reader

A novel dual-band circularly polarized antenna with broadband characteristic for RFID system is proposed.The antenna consists of an upper layer of rotationally symmetric folded dipoles,slot-loaded square patch,and a lower layer of compact feed network.The circularly polarized radiation of the low frequency 0.9 GHz and high frequency 2.45 GHz are respectively excited by two external ports.The antenna was modeled,simulated and optimized with the aid of HFSS.Finally,it is fabricated using FR4 plate and tested.The size of the antenna is 0.6λ0×0.6λ0×0.1λ0(λ0 is the free-space wavelength at 0.9 GHz).The measured impedance bandwidths are 91.1%and 4.9%while the axial ratio(AR)<3dB bandwidths are 91.1%(4.9%)and 87.8%(1.3%)at the low and high bands,respectively.The measured peak gain is 5.48 dBic at 0.9 GHz and 3.63 dBic at 2.45 GHz meanwhile the minimum axial ratio is 1.1 dB and 1.2 dB in the two operating bands respectively.The radiation patterns of the antenna are symmetric and stable in the two operating bands.The proposed antenna can not only meet the requirements of RFID read-and-write applications in global UHF band(0.84~0.96 GHz)and ISM band(2.4~2.5 GHz),but also has the advantages of low cost,easy processing and etc.,which will have a good application and prospects in the field of Internet of Things.