小型化双频圆极化天线设计

Design of miniaturized dual-band circularly polarized antenna

为减少多径损耗、抗极化失配并同时满足无线设备对小型化、多频段的需求,提出了一种小型化、宽轴比的双频圆极化天线。天线采用相对于馈线不对称的矩形接地板,实现Wi-Fi(5.15~5.35 GHz)频段圆极化辐射。在此基础上,通过对接地板进行切角处理并刻蚀两个宽度不等的L形缝隙,在不改变天线尺寸的情况下产生低频谐振频率,使天线同时工作在UHF(840~960 MHz)频段,并具有小型化特性。通过在接地板上加载两个高度不等的矩形枝节以及在圆形辐射贴片上刻蚀臂长不等的斜十字形槽,拓宽低频轴比带宽并降低两个频段的轴比值,实现宽轴比的双频圆极化辐射天线。天线最终尺寸为60 mm×60 mm×1.6 mm。仿真与测试结果表明:天线的相对阻抗带宽分别为62.6%(0.79~1.51 GHz)和34.1%(3.84~5.42 GHz),3 dB轴比带宽分别为108.1%(0.34~1.14 GHz)和7.2%(5.08~5.46 GHz),具有良好的辐射特性,可应用于UHF和Wi-Fi频段。

A miniaturized dual-band circularly polarized antenna with wide axial ratio bandwidth was proposed to reduce multipath loss,resist polarization mismatch and meet the demand for miniaturization and multi-band in wireless devices.An asymmetric rectangular ground plane with respect to the microstrip line was utilized to realize circular polarization radiation in the Wi-Fi(5.15-5.35 GHz)frequency band.Based on this,the resonance can be produced at low frequencies without changing the size of the antenna by cutting-corner on the ground plane and etching two L-shaped slots of unequal width.As a result,the operation in the UHF(840-960 MHz)band was allowed,and the miniaturization of the antenna was realized.Then,by loading two rectangular stubs with unequal height on the ground plane and etching a crisscross slot with different arm lengths on the circular radiation patch,the axial ratio bandwidth of the lower frequency band was broadened and the axial ratio value of the two frequency bands was reduced.A dual-band circularly polarized antenna with wide axial ratio bandwidth was realized.The dimension of the antenna is 60 mm×60 mm×1.6 mm.The simulation and experimental results show that the relative impedance bandwidths of the antenna are 62.6%(0.79-1.51 GHz)and 34.1%(3.84-5.42 GHz),respectively.And the 3 dB axial ratio bandwidths are 108.1%(0.34-1.14 GHz)and 7.2%(5.08-5.46 GHz),respectively.The antenna has superior radiation performance,which is suitable for UHF and Wi-Fi band application.