新型高温陶瓷天线罩材料的研究进展

导弹天线罩是保护导弹导引头天线在恶劣的环境下能正常工作的一种装置,其性能直接影响导弹的制导精度.天线罩材料经历了如下发展路径:氧化铝陶瓷→微晶玻璃→石英陶瓷→陶瓷基复合材料,并逐步向宽频带、多模通讯与精确制导方向发展.近年来,陶瓷基高速导弹天线罩技术发展十分迅速,重点介绍了高温陶瓷导弹天线罩的主要材料体系,并对各种体系陶瓷天线罩材料的特点及国内外研究现状进行了评述.     

雷达天线罩技术及其电性能研究综述

综述了雷达天线罩技术的现状和发展趋势,介绍了雷达天线罩的材料(包括基体材料、增强材料和夹芯材料)、罩壁结构以及成型工艺,并且从雷达天线罩的透波特性和辐射特性两个方面详细介绍了雷达天线罩电性能研究分析方法,为雷达天线罩的设计与制造奠定了基础.     

高速宽频带导弹天线罩的耐烧蚀透波材料研究

对聚四氟乙烯(PTFE) 和玻纤增强PTFE 进行了差热分析, 确定了玻纤增强PTFE 的基 本工艺参数, 根据对高速宽频带防空导弹天线罩蒙皮的性能要求, 考察玻纤增强PTFE 拉伸强度 和介电性能。结果表明: 11% 短玻纤和37% 玻纤布(重量百分含量) 增强PTFE 具有最高的拉伸强 度和良好的介电性能。由于某种粒子的加入, 在扫描电镜下很容易观察到PTFE 的结晶现象。      

无机天线罩功能材料的新进展

从高温天线罩功能材料的性能要求出发,回顾了无机天线罩材料的发展历程,综述了近年来氧化物系、氮化物系和磷酸盐系陶瓷基天线罩复合材料的研究进展.     

机载雷达天线罩的设计与制作

选择某一机载雷达天线罩,根据其外形尺寸进行厚度设计,使用HFSS仿真软件对所得的天线罩进行电磁仿真。天线罩使用玻璃纤维增强环氧树脂作为主要材料,为控制天线罩的厚度等尺寸精度,采用RTM成型工艺进行天线罩的制作,设计与制作合格的天线罩。     

地面雷达天线罩风载下的数值模拟与风洞试验研究

风荷载是地面雷达天线罩的主要荷载之一,风荷载会影响雷达罩的强度和稳定性,并会间接影响到雷达天线的使用精度,导致雷达天线的指向偏差和偏焦。所以雷达天线罩的风载研究是雷达天线罩设计的重要环节之一。该文用Solid Works建立雷达天线罩的微缩模型,借助ANSYS ICEM CFD进行结构化网格划分,然后导入到FLUENT中进行风载的流场计算。在FLUENT流场计算中,选用了标准K-ξ模型、RNG K-ξ模型和Reliable K-ξ模型,对三种模型下的罩体迎风面、侧面以及背风面风压分布规律进行了对比,最终选用更加适合该文的RNG K-ξ模型。并对风速为V=20 m/s、V=28 m/s和V=36 m/s下的雷达天线罩的数值模拟和风洞试验的风压结果对比。结果表明:在罩体迎风面的风压曲线拟合的较好,而在罩体侧面及背风面的风压曲线出现了一定的偏离;风速越大,风压显著增大。通过对风载下地面雷达天线罩在数值模拟方法和风洞试验下风压分布的比较,可见数值模拟方法在雷达天线罩的设计中扮演重要角色,仿真得到的数据也可为实际工程领域的风洞试验提供数据支持。     

树脂基复合材料在导弹雷达天线罩中的应用

介绍了对导弹天线罩材料性能的要求,并综述了用于导弹雷达天线罩的聚合物基复合材料的研究进展。     

无机天线罩材料研究进展

对高马赫数导弹天线罩材料的性能要求进行了评述，综述了国外天线罩材料的研究进展，特别是重点介绍了美国等军事强国近年来研制的天线罩材料的温度、强度、介电特性以及工艺性能。分析了我国在该领域的研究现状，并提出了今后的发展方向。     

高超音速导弹天线罩用陶瓷基材料的研究进展

综述了高超音速导弹天线罩用陶瓷基材料的研究进展,简述了高超音速导弹天线罩材料性能要求,从氮化硅基材料、氧化硅基材料、磷酸盐基材料等方面介绍了高超音速导弹天线罩用陶瓷基材料的研究现状,包括材料选择、制备技术和加工工艺等,指出了高超音速导弹天线罩材料的发展方向。     

导弹天线罩技术简介

导弹天线罩是保护导弹导引头天线在恶劣的环境下能正常工作的一种装置，其性能直接影响导弹制导精度。近年来，导弹天线罩技术发展十分迅速，本文介绍了导弹天线罩发展的历史、现状及发展趋势．     

高性能舰载雷达罩透波材料的优化设计

通过常规基体、增强材料和芯材等主要原材料之间的优化复合设计,开展单板、三夹层结构和五夹层结构各形式复合材料之间的制作、电性测试与分析,优化设计出了一种新型兼顾电性、力学性能的功能型五夹层结构复合材料,满足了高性能舰载雷达宽频带、高透波等电性指标要求,同时还满足了其高比强、刚度的力学指标要求,解决了传统型设计和材料通常无法满足其电性能、强刚度、低成本制作的矛盾。     

Graded Dielectric Inhomogeneous Planar Layer Radome for Aerospace Applications

Controllable artificial dielectrics are used in the design of radomes to enhance their electromagnetic (EM) performance. The fabrication of such radome wall structures with controllable dielectric parameters seems to be an arduous task. Further even minor fluctuations of dielectric properties of radome wall due to fabrication uncertainties tend to result in drastic degradation of radome performance parameters. In the present work, a novel inhomogeneous radome with graded variation of dielectric parameters is proposed which limits the constraints on fabrication and facilitates excellent EM performance characteristics. This radome wall consists of five dielectric layers cascaded such that the middle layer has maximum dielectric constant and electric loss tangent. The dielectric parameters of the layers on both sides of the middle layer decrease in a graded (or step-wise) manner. The EM performance characteristics of the IPL radome with graded dielectric parameters are superior to that of conventional monolithic half-wave radome.     

Stability design of honeycomb sandwich radome with asymmetric shape

The die radome, which is made of honeycomb sandwich structure, should be entirely refitted, for a big electronic observation facility is being fixed at the head section of an aircraft. In this work, the stability design of honeycomb sandwich radome is investigated. Initially, a local buckling failure is observed in the refitted radome during the preliminary calculation. Then design improvements are made to the existing radome, like some L-shaped stiffeners are added on the inner surface of metal faring in order to improve the stability of radome. In this way, the critical buckling load of radome increases more than 10 times. Different layout schemes for the stiffeners are studied during this work, and the best structure layout is obtained by discrete optimization method and also the relationship between stability and bar spacing is examined. Finally, the stability of radome under 45 load cases is calculated to validate the design. The result shows that the optimized design greatly improves the stability of radome. This method can be applied to structure design in preliminary assessment.     

高硅氧/有机硅透波材料性能研究

对低残炭率甲基硅树脂基透波复合材料进行了介电性能和力学性能研究,结果表明,采用低残炭率甲基硅树脂作为透波材料基体研制的透渡复合材料的介电性能优良,经低于1600℃高温处理后,在电磁波频率为9.30GHz时测试的介电常数小于3.5,透波率高达90%以上.采用甲基硅树脂研制的透波材料克服了传统树脂基透波材料耐热性差、强度低的缺点,是集防热、承载、透波和抗烧蚀等功能一体化的较理想的耐高温多功能透波复合材料.     

Broadbanding of A-sandwich Radome Using Jerusalem Cross Frequency Selective Surface

Enhancement of electromagnetic performance of A-sandwich radome using aperture-type Jerusalem cross frequency selective surface (FSS) is presented. The Jerusalem cross FSS array is embedded in the mid-plane of the core of Asandwich radome to enhance the EM performance parameters over the entire Xband. For modeling the Jerusalem cross FSS embedded radome panel and evaluation of its EM performance parameters, equivalent transmission line method in conjunction with equivalent circuit model is used. A comparative study of Jerusalem cross FSS embedded A-sandwich radome and A-sandwich radome of identical material and thickness (core and skin layers) indicate that the new wall configuration has superior EM performance as compared to the A-sandwich wall alone configuration. The excellent EM performance of Jerusalem cross FSS embedded A-sandwich radome makes it a desirable choice for the design of normal incidence radomes (hemispherical/ cylindrical), near-normal incidence radomes (paraboloidal) and highly streamlined airborne nosecone radomes.     

复合材料雷达罩耐鸟撞和电磁性能综合优化设计

对蜂窝夹芯复合材料雷达罩进行耐鸟撞优化设计以及耐鸟撞和电磁性能综合优化设计,优化设计变量是雷达罩分段后的总厚度和比例等,耐撞性优化目标是最大限度的减小雷达罩的损伤面积和保护雷达罩内的设备安全,体现在数值计算中减小雷达罩的失效单元数和鸟体的剩余动能;耐鸟撞和电磁性能的综合优化目标除满足以上目标外,也要求使电磁参数指标达到最优。优化软件中集成了显式动力分析软件LS-DYNA和电磁分析软件FEKO,采用了适合于复合材料壳单元冲击损伤的Chang-Chang模型。某算例的优化结果表明：合理的优化设置可以实现蜂窝夹芯复合材料雷达罩的耐鸟撞和电磁性能优化要求,并提高工程设计效率。     

Aramid/epoxy composites sandwich structures for low-observable radomes

Low-observable radomes are usually made of E-glass/epoxy composite due to its low dielectric constant which is necessary not to interfere electromagnetic (EM) wave transmission characteristics. Since aramid fibers have lower dielectric constant and higher strength than those of E-glass fiber, aramid fiber radome structures may have better the EM transmission and mechanical characteristics than those of E-glass/epoxy radomes. In this work, the low-observable radome was constructed with a sandwich construction composed of aramid/epoxy composites faces, foam core and Frequency Selective Surface (FSS) which had the abilities of transmitting EM waves selectively in the X-band range. The EM wave transmission characteristics of the low-observable radome were simulated by a 3-dimensional electromagnetic analysis software and also measured by the free space measurement method with respect to the pattern size of FSS and foam cores. The mechanical properties of the low-observable radome made of aramid/epoxy composite were measured by the 3-point bending test and compared to those of the conventional low-observable radome made of E-glass/epoxy composite.     

Equivalent circuit for broadband underwater transducers

A method is presented to determine the equivalent circuits of broadband transducers with 2 resonances in the frequency band of interest. The circuit parameters are refined by least-squares fitting the measured electrical conductance data with this model. The method is illustrated by computing the conductance and susceptance of the equivalent circuits of 3 types of broadband transducers and comparing them with the measured values. The equivalent circuit of a transducer is necessary for designing filters that match the impedances of the transducer and the power amplifier that drives the transducer.