频选天线罩对阵列天线波束扫描特性影响分析

Analysis of influence of FSS radome on array antenna scanning

[目的]针对频选天线罩对阵列天线波束扫描的不利影响,提出一种综合优化频选天线罩的方法。[方法]首先,设计一款由25个对称阵子组成的阵列天线和一款大角度入射时仍具有较好阻抗带宽和滤波性能的频选天线罩。然后,在此基础上使用HFSS软件对由频选天线罩—阵列天线组成的系统进行仿真,以阵列天线的辐射特性受影响最小为目标,确定频选天线罩的尺寸,以及频选天线罩与阵列天线间的距离。最后,比较单独阵列天线与频选天线罩—阵列天线系统的扫描角度变化。为验证理论的正确性,在实验中对不同扫描角度下带有频选天线罩的阵列天线方向图予以测试。[结果]结果显示,当频选天线罩与阵列天线间距离为0.5λ时,频选天线罩对阵列天线副瓣与后瓣增益的影响最小,当阵列天线主瓣波束扫描角度达到40°时,频选天线罩会对阵列天线扫描角产生约0.25°的变化。[结论]经过分析与优化的频选天线罩不会对阵列天线辐射性能产生不利影响,该设计方法可用于更大尺寸的阵列天线加频选天线罩。

[Objectives]Aiming to resolve the adverse effects of frequency selective surface(FSS)radomes on array antenna beam scanning,a method for optimizing FSS radomes is proposed.[Methods]First,an array antenna with 25 half-wave dipole elements is designed.At the same time,a wideband Jerusalem structure is designed as a frequency selection unit with the goal of bandwidth matching and stable filtering performance at high angle incidence.On this basis,HFSS software is used to optimize the distance between the FSS radome and array antenna with the lowest gain on the side lobes and back lobes.Finally,the size of the FSS radome is determined by the beam width and scanning angle of the array antenna,and the scanning angle error of a separate array antenna is compared with an FSS radome-array antenna system.In order to verify the accuracy of the theory,the array antenna pattern is tested with the FSS radome at different scanning angles.[Results]The results show that when the distance of FSS radome between array antenna is 0.5λ,the influence of FSS radome on the secondary and rear lobe gains of the array antenna is minima;when the scanning angle is up to 40°,the FSS radome produces an error of about 0.25°to the array antenna scanning angle.[Conclusions]The FSS radome designed by the appropriate method has little effect on the beam scanning direction of the array antenna.This method can also be used in the design of larger array antennas and FSS radomes.