Ku波段电磁涡旋相控阵列天线设计

Design of phased antenna array for generating electromagnetic vortex in Ku band

为了能产生性能更好携有轨道角动量的涡旋电磁波,采用微带天线技术,设计了一种新型的相控微带阵列天线.以同轴馈电的圆微带天线为单元,将8个、16个相同的单元天线等间隔的分布在一个同心圆上分别组成两个单圆环和一个双圆环结构的相控阵列天线,并采用等幅且同一环的相邻单元间相位差为常数的方式进行激励.通过电磁场全波仿真软件Ansoft HFSS建模并优化,单圆环和双圆环阵列结构均在中心频率为15 GHz处获得了携有轨道角动量的涡旋辐射方向图.结果表明:虽然单圆环结构的相控阵列天线可通过增加阵元数来改善电磁涡旋性能,但不可避免的造成更大的天线体积;而利用双圆环结构,由于增加一个内环设计自由度,结合内外环的协同优化仿真,通过设置适当的天线阵列结构和相位延迟,双圆环结构较单圆环结构产生的涡旋电磁波有更小的中心轴线开口张角,具有更强的涡旋方向性和更高的辐射增益.

Phased microstrip array antenna is an effective method to generate vortex electromagnetic beam containing orbital angular momentum(OAM),and a good design of the multi-mode OAM microstrip array antenna is crucial to improve the vortex performance.We consider circular microstrip antenna with coaxial feed as the element to compose the circular antenna array,which is excited with unit amplitude and equal phase delay from element to element.Two single-ring uniform circular array antennas are designed with the array elements number as eight and sixteen respectively,and a dual-ring uniform circular array antennas is designed with eight elements in inner ring and sixteen elements in outer ring.The OAM-carrying electromagnetic vortex can be generated at 15 GHz from both sing-ring and dual-ring uniform circular array antennas,and the vortex characteristics,such as radiation patterns and OAM modes,are analyzed in detail by using a full-wave electromagnetic field simulation code HFSS.According to the simulation and optimization,with the increase of elements number in the sing-ring structure,we get the better electromagnetic wave vortex performance at the cost of a larger size array antennas.In contrast,through using collaborative optimization simulation combined with inner and outer ring,the vortex properties of dual-ring structure is better than that of the single-ring structure at suitable array configurations and phase shifts.