FSS雷达罩电磁特性的曲面效应机理研究

Frequency Selective Surface (FSS) is a type of 2-D structure which has a characteristic of reflecting or transmitting the electromagnetic waves in selected waveband. Bandpass FSS has been onsidered as the most possible solution to the stealthy problem of the radar antenna, for there characteristics of high inband transmission and total outband reflection. Radomes usually have inextensible surfaces, so it is difficult to mapping a planar infinite periodic array to a radome directly. On the other hand, it is hard to conduct an efficient analysis of the electromagnetic characteristic for an electrically large FSS radome, for the limit of the technology level of the computational electromagnetic and the computer hardware. Design a planar infinite FSS and mapping the structure and electrical properties to the radome is the only method for the design of a practical radome with inextensible surfaces. But this method has no systemic theoretical basis, and no clear directive law or rule up to now. This project will devote to pick the curved surface effects which have obvious influence on the electromagnetic characteristics of a complex surface FSS, and establish relationship between those curved surface effects and the electromagnetic characteristics by analyzing the electromagnetic responses of the complex surface FSS at the incident conditions with different incident angles, frequency and polarization. Then summarize the influence law of the electromagnetic characteristics of the radomes caused by the curved surface effects, and search the method of mapping the planar infinite FSS to the practical FSS radome with the least electromagnetic characteristics distortion. The achievements of those works will found a systemic theoretical basis for the FSS radome design.

对电磁波具有选择性透过或阻止功能的频率选择表面(FSS)雷达罩是实现武器装备雷达天线隐身的重要手段。实际雷达罩通常是不可展曲面复杂结构，限于当前软硬件技术水平，在设计阶段对双曲面FSS雷达罩的电磁特性进行快速分析几乎是不可能实现的。通过平面无限大FSS的快速设计、分析并向雷达罩曲面上映射来获得满足电性能要求的FSS雷达罩局部结构设计，是目前实用双曲FSS雷达罩设计的几乎惟一途径。这种设计方法还存在无系统的理论基础作为支撑、无明确的规律和方法作为指导等难题。本课题拟通过不同频率、不同入射角、不同极化的入射电磁波作用下的电磁响应特性研究，揭示阵列截断、曲率、阵子相对位置关系等强效应因素对FSS隐身雷达罩的电磁特性影响规律，建立电性能畸变最小的前提下由平面无限大阵列结构映射到曲面FSS的方法，为实用FSS雷达罩的设计奠定基础。

本项目针对频率选择表面雷达罩的设计特点，通过对平面无限大周期阵列结构向曲面雷达罩部件上映射的方法研究入手，对可能影响FSS雷达罩电性能的结构因素进行了初步分析和分类，将可能对FSS雷达罩电性能造成较大影响的结构因素分为阵列规模、边缘截断、阵子排布、折角/棱边拼接和曲率共5种。.首先，针对这5种强效应因素设计了解耦方法，尝试将这5种效应因素对FSS电性能的影响尽可能单独分离出来分析。针对可以单独分离出来的影响因素，如阵列规模、阵子排布等，建立了电性能评价参数与效应因素表征参数之间的解析规律或解析方法；对于难以单独分离出来的效应因素或者难以用简单参数来表征的效应因素，给出了定性规律、机理分析和相对实用的快速分析方法。.其次，将5种强效应因素按照分析方法特点与耦合程度分为空间排布效应与边缘效应两类，提出了同类效应的统一的分析方法：针对空间排布效应，利用平面无限大FSS的场解按空间位置叠加来获得纯粹阵子空间排布引起的电性能表征；针对边缘效应，提出利用基于简化模型快速分析得到的场分布特征对平面无限大FSS的场解进行修正的方法，来获取含边缘效应的FSS阵列结构电性能。.最后，瞄准曲面FSS雷达罩的结构设计需求，提出了一种最小结构畸变的平面无限大周期阵列向曲面雷达罩部件上映射的方法和相应的局部阵子调节方法；在该映射及调节方法的基础上，结合效应因素对电性能影响的快速分析方法，建立了以FSS雷达罩电性能需求为目标的设计迭代方法。该方法的效果目前正在与相关厂所合作进行检验。