一种用于射频识别阅读器的双频宽带圆极化天线

A Dual-band Broadband Circular Polarized Antenna for Radio Frequency Identification Reader

该文设计了一种紧凑的用作射频识别(RFID)阅读器的双频宽带圆极化天线。天线由弯折处理的矩形贴片、L形贴片和三角形地板构成,通过微带线进行馈电。两个辐射贴片分别独立控制高低两个频段,其轴比带宽也可独立调整,三角形地板可以使横向电流和纵向电流发生变化,从而改变横向电流和纵向电流的比值大小,实现圆极化性能。天线尺寸为0.92λ_(0)×0.92λ_(0)×0.0064λ_(0)(λ_(0)为2.40 GHz时的自由空间波长)。测试结果表明在超高频(UHF)频段该天线实现了49%(0.77~1.27 GHz)的阻抗带宽和46%(0.84~1.34 GHz)的轴比带宽,在无线局域网(WLAN)频段实现了47.5%(1.54~2.50 GHz)的阻抗带宽和24.2%(1.96~2.50 GHz)的轴比带宽,可以完整覆盖UHF和WLAN两个频段,具有良好的辐射特性。与其他双频圆极化天线相比,该天线整体结构紧凑、设计简单、避免了使用复杂的馈电网络,且具有较宽的3 dB轴比带宽。

A compact dual-band wideband circularly polarized antenna for Radio Frequency IDentification(RFID)reader is designed.The antenna consists of a curved rectangular patch,an L-shaped patch,and a triangular floor,which is fed through a microstrip line.The two radiation patches control the high and low frequency bands independently,and their axial ratio bandwidth can also be adjusted independently.The triangular floor can change the transverse current and the longitudinal current,so as to change the ratio of the transverse current and the longitudinal current to achieve circular polarization performance.The antenna dimensions are 0.92λ_(0)×0.92λ_(0)×0.0064λ_(0)(λ_(0) is the free space wavelength at 2.40 GHz).The measurement results show that the proposed antenna achieves an impedance bandwidth of 49%(0.77~1.27 GHz)and an axial ratio bandwith of 46%(0.84~1.34 GHz)in the Ultra High Frequency(UHF)band,and achieves 47.5%(1.54~2.50 GHz)impedance bandwidth and 24.2%(1.96~2.50 GHz)axial ratio bandwidth in Wireless Local Area Networks(WLAN)band.It can completely cover UHF and WLAN two frequency bands and has good radiation characteristics.Compared with other dual-frequency circular-polarized antennas,the antenna has compact structure and simple design,avoids the use of complex feed network,and has a wide bandwidth of 3 dB axial ratio.