一种空中辐射场测量用低轴比圆极化天线设计

Design of low axial ratio circularly polarized antenna for airborne radiation measurement

在进行高功率微波(HPM)空中辐射场测量时,由于来波信号极化角度难以确定和受空中平台姿态影响等因素,普通线极化接收天线难以确保极化匹配,天线的极化失配会进一步降低辐射场参数测量的精确性。为了降低极化失配影响,在梯形微带圆极化单元天线分析设计的基础上,采用四阵元依次旋转90°和依次移相馈电的方式组建了一种低轴比微带圆极化阵列天线,该天线采用功分器和移相器作为馈电网络,天线在9.7GHz实测增益约为9.4dB,1dB波束宽度约17.4°,轴比约0.4dB。应用该圆极化天线可将极化失配引入的不确定度降低到0.2dB以下,可满足高功率微波空中辐射场的精确测量需求。

The polarization mismatch caused by variation of signal polarization angle and base gesture often leads to accuracy decrease in high power microwave(HPM)radiation precise measurement.It is commonly difficult to realize polarization match with linearly polarized antenna.Based on analysis of trapezoidal circularly polarized antenna,method of sequentially 90°rotation and phase shift with power divider and phase shifters as feedwork,a novel circularly polarized microstrip array antenna with low axial ratio feature was designed.The experimental behavior of this antenna shows its gain is 9.4 dB,1 dB angular width is 17.4°,and axial ratio is as low as 0.4 dB.The application of the designed circularly polarized antenna is able to effectively reduce polarization mismatch uncertainty to less than 0.2 dB,which satisfies the requirement of airborne HPM radiation measurement.