一种双频四模极化可重构天线

A Dual-Band Quad-Polarization Reconfigurable Antenna

极化可重构天线是一种极化状态可切换的新型天线,它具有减少系统中天线数量、利于频率复用等优点.本文基于模式可切换馈电网络,提出了一种具备两个工作频带(1 GHz和2.1 GHz)和四种极化状态(0°和90°线极化和左、右旋圆极化)的直流偏置电压数量较少的双宽带极化可重构微带天线.双频比可实现范围为1.7~3.5.本文详细介绍了双频可切换馈网和天线的设计过程.本文在分支线耦合器的基础上加载4个开路枝节和12个二极管,通过切换二极管状态使馈网输出信号幅度和相位可以在四种模式之间切换,从而满足四种极化状态的激励条件;并且基于参数分析,提出了调节双频比和提高轴比带宽的方法.天线方面,本文在双层L探针贴片天线的基础上设计了一种准同轴去耦结构和一种T形结匹配结构.仿真结果表明天线具有良好的双频双极化性能.最后,对馈电网络和天线的整体进行了仿真和加工实测.实测结果表明,该天线在0.94~1.07 GHz(13%)和1.99~2.27 GHz(12.6%)两个较宽的频带内仅用2个直流偏置电压(不包括地板电位)就实现了四种极化状态的切换,低、高频带内线极化状态的法向增益分别为7.6 dBi和7.3 dBi,圆极化的法向增益分别为6.3 dBic和5.9 dBic.本文设计的双频四极化可重构天线为RFID系统、WLAN系统和卫星导航系统提供了新的解决方案.

Polarization reconfigurable antenna is a state-switchable antenna with advantages of reducing number of an⁃tennas used in a system as well as frequency reuse.In this article,a dual-band reconfigurable microstrip antenna with quadpolarization diversities in both operating frequency bands(1 GHz and 2.1 GHz)is presented based on a mode-switchable feed network.The achievable frequency ratio is 1.7-3.5.The article presents the design of feed network and antenna in detail.Due to the 4 open-ended stubs and 12 p-i-n diodes,the amplitudes and phases of the feed network can switch among four oper⁃ating modes which meet the excitation conditions of four polarization states.A method to adjust frequency ratio and improve the bandwidth of axial ratio is proposed based on the analysis of key parameters of the feed network.In terms of the radiator,a quasi-coaxial decoupling structure and a T-junction matching structure are proposed as modifications of L-probe feed patch antenna.Simulation results verify a dual-band dual-polarized performance.Finally,the integrated system is simulated and measured.Measured results show that the proposed antenna implements four polarization states in 0.94-1.07 GHz(13%)and 1.99-2.27 GHz(12.6%)by utilizing only two dc bias voltages.The broadside gains for linearly polarized states at high and low frequencies are 7.6 dBi and 7.3 dBi,respectively.Those for circularly polarized states are 6.3 dBic and 5.9 dBic,re⁃spectively.The proposed dual-band quad-polarization reconfigurable antenna provides a new solution for RFID(Radio Fre⁃quency Identification)systems,WLAN(Wireless Local Area Network)systems and satellite navigation systems.