曲率对有限曲面狭缝阵列传输特性的影响

扩展互导纳法用于研究有限曲面狭缝阵列的传输特性,分析了一维弯曲效应以及单元列数、曲率等因素对磁流分布、散射方向图及频率响应曲线的影响.结果表明,曲面张角是衡量弯曲效应的主要参数. 当曲面张角较大时(120°以上),弯曲效应显著,单元磁流分布剧烈起伏,散射方向图波束展宽且副瓣电平升高,谐振频率、传输带宽及功率透射系数等频率响应特性均发生较大变化.当曲面张角较小时(60°以下),仅边缘附近的单元磁流分布受到曲率影响,散射方向图与传输特性均接近于有限平面阵列,表明此时可近似忽略弯曲效应. 关键词： 频率选择表面 狭缝阵列 传输特性 曲率     

Transmission properties of frequency selective structures with air gaps

The transmission properties of compound frequency selective structures with dielectric slab and air gaps were investigated by computation and experimentation.Mechanism analyses were also carried out.Results show that the air gaps have a distinct influence on the transmission properties.Resonant frequency of the structure would increase rapidly when the air gap appears.After the gap gets larger to a specific value,generally 1/5 wavelength corresponding to the resonant frequency,the transmission properties would change periodically with the gap thickness.The change of transmission properties in one period has a close relationship with the dielectric thickness.These results provide a new method for designing a bandpass radome of large incidence angle and low loss with the concept of stealth shield radome.     

单层带通FSS结构中空气间隙的影响

以狭缝阵列为例,利用模匹配法计算分析,并结合实验,针对即贴型频率选择表面(FSS)与介质板复合结构中的空气间隙进行研究.结果表明,空气间隙对FSS结构的传输特性影响与介质厚度和空气间隙大小密切相关.合空气间隙时谐振频率比无空气间隙时向高处漂移.空气间隙的厚度达到一定值后,传输特性随空气间隙厚度周期性变化.在同一周期中,传输特性的变化幅度取决于介质厚度.基于研究结果提出了隐身屏蔽罩概念,为大入射角下低损耗FSS天线罩的应用提供了新思路.     

平面FSS阵列的一维截断效应

基于互导纳法进行有限频率选择表面(FSS)计算分析,研究狭缝阵列一维截断时磁流分布、散射方向图及传输特性的变化,考察了单元列数、入射角等因素的影响.与无限平面阵列相比,截断导致边缘单元磁流分布起伏,部分频率产生表面波,散射方向图波束展宽且副瓣电平升高,功率透射系数发生变化,仅谐振频率和传输带宽与无限平面阵列基本相同.