基于电路模拟雷达波吸收器的隐身天线罩研究

Radome is an important component part of the antenna system as well as radar stealth platform. However, the scattering from radome leads to increased radar cross-section and thus becomes a dominant threat to the stealth performance of the platform. Literature shows that the increased radar cross-section of radome is dominantly attributed to the strong reflection from the frequency-selective surface involved in the radome. In order to reduce the radar cross-section of radome, this research will concentrate on the reflection reduction of frequency-selective surfaces and propose the design method of novel stealth radome with high performance, in combination with the circuit analog absorber. Based on the transmission line and microwave network theory, analysis of theoretical requirements and key techniques for effectively integrating the two-dimensional frequency-selective surface with circuit analog absorber will be conducted, so that the passband with small insertion loss can be retained and the reflection at frequencies below and above the passband can be reduced. Meanwhile, designs of stealth radome suitable for oblique incidence of plane wave and cylindrical conformability will be investigated so as to lay the foundation for practical applications. The stealth radome with its passband designed within an absorption band will be realized in this study, which is of practical significance to improve the stealth performance of the antenna system and corresponding platform. This study will provide theoretical analysis, physical implementation and measurement methods for stealth radome containing two-dimensional frequency-selective surfaces and enrich the design theories of stealth radome.

天线罩是天线系统与雷达隐身平台的重要组成部件。然而，天线罩引起的强散射将增大平台的雷达散射截面，成为影响平台隐身性能的主要因素。研究表明，天线罩中所含频率选择表面产生的强反射是天线罩散射截面增大的主要原因。针对天线罩的散射截面减缩问题，本项目将结合电路模拟雷达波吸收器，系统研究如何降低频率选择表面的强反射，提出高性能的新型隐身天线罩设计方法。以传输线与微波网络理论为基础，研究二维频率选择表面与电路模拟雷达波吸收器有机集成的理论条件与关键技术，在保持通带内良好传输性能的同时，确保带外低频端和高频端只有较低的反射。同时，研究适用于斜入射平面波与柱面共形的隐身天线罩设计，为实际应用奠定基础。项目将实现传输窗口设计于吸收频带之中的隐身天线罩，它对提升天线系统与平台整体的雷达隐身性能具有实际意义。项目研究成果将为该类型隐身天线罩提供切实可行的理论分析、物理设计与实验测试方案，丰富隐身天线罩设计理论。

围绕频率选择表面的强反射减缩问题，本项目主要研究了基于电路模拟雷达波吸收器与基于无源相位抵消原理的解决办法与设计。主要内容与结果包括：1）将单层电路模拟雷达波吸收器与二维频率选择表面相结合，通过等效电路分析了在通带外实现强反射减缩以及在通带内保持传输性能的工作原理。通过参数调整，稳定了指定斜入射角度时的反射与传输性能，并进一步获得了柱面共形的吸透一体化频率选择表面设计。2）为了拓展单层电路模拟雷达波吸收器的工作带宽，通过等效电路模型发现了双层电路模拟雷达波吸收器的工作频带内可存在五个谐振，分析了在反射幅度随频率变化的曲线上影响谐振可见性的因素。根据微波电阻器的实际阻抗，依靠构建多谐振实现了双层电路模拟雷达波吸收器的带宽与厚度综合性能的先进结果，可为后续的吸透一体化频率选择表面的吸波带宽拓展研究奠定基础。3）为了探索减缩带通频率选择表面强反射的新方法，提出了基于无源相位抵消原理的多层频率选择结构，该结构由具有异相反射特性的超单元以一维或二维棋盘构型组合而成。在降低强反射的同时，通带内的传输特性也得以保持。并且与现有设计不同，该方法能避免在降低频率选择表面强反射的设计中使用有耗材料或阻性器件。