共查询到18条相似文献,搜索用时 171 毫秒
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介绍AXB型吸波材料的性能.用AXB型吸波材料建造的天线近、远场测量微波暗室,10m半电波暗室和RCS测量微波暗室的技术指标都符合相关标准的要求. 相似文献
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基于射线追踪法开发的静区电平仿真软件应用于AFA型吸波材料(难燃型吸波材料)铺设的微波暗室静区性能仿真。软件以国内暗室性能检测机构的喇叭天线数据为依据设定发射天线的辐射特性模拟函数,得到发射天线的直射波方向图。以AFA 型吸波材料的实测数据为依据设定吸波材料的吸波特性模拟函数,计算微波暗室各面墙壁反射电场在静区内叠加后的总反射电场值,并据此得到静区内的反射电平分布。仿真与实测结果表明,1 GHz 以下静区反射电平仿真结果下限值与测试结果偏差相对较大;1 GHz 以上两者偏差小于1 dB,吻合较好。验证了该仿真软件能够快速并较准确地用于微波暗室吸波工程的设计与评估。 相似文献
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详细介绍了电波暗室用吸波材料的种类、制造工艺,以及电波暗室用吸波材料的反射率、阻燃性、耐功率等性能指标,为暗室建造企业在选择吸波材料时提供参考. 相似文献
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吸波材料的喇叭测试系统是一种独特而优秀的测试系统,它使得用于无回波暗室的低频吸波材料的鉴定测试变得更容易,可对反射衰减为-50dB的吸波材料进行测试,该项技术已获美国专利。 相似文献
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以高功率微波电磁脉冲为代表的强电磁环境使得吸波材料的使用环境发生了极大改变,常规吸波材料因其低功率容量已不适用于大功率微波器件。文章综述了吸波材料强电磁环境效应的研究进展以及作者团队在该领域的主要研究成果。分析了吸波材料强电磁环境效应作用原理,采用仿真与实测结合的方式研究了强电磁环境下吸波材料的失效模式。结果表明,强电磁环境下的击穿效应、热效应及非线性效应是导致羰基铁/碳粉填充吸波橡胶失效的主要原因,而吸波超材料的周期结构优化、介质层高导热特性均有利于表面电流分布的均匀性,进而改善强电磁环境效应。最后提出了高功率微波电磁脉冲环境下吸波材料研究发展展望。 相似文献
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The development of an access device for a large-scale shielded facility that requires no maintenance, can accommodate an unimpeded flow of pedestrian traffic, and may cost less than alternative access devices is presented. The corridor is composed of waveguides that attenuate signals over the lower frequency region of the overall electromagnetic spectrum and an absorptive or anechoic chamber that attenuates signals over the higher frequency region. The required attenuation of the waveguide and the reflection performance of the absorber material are determined by the attenuation (shielding) requirements of the facility. It is found through waveguide theory and modeling that a critical issue is the amount of shielding providing in the transition region above the waveguide cutoff and below the frequency range where the absorber material is most effective. Applicable theory is presented, design considerations are summarized, and a modeling approach is described. Actual construction details, which were used in two corridors currently installed and tested in large shielded facilities, are set forth 相似文献
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This paper describes a novel, lightweight technique for significantly improving the low-frequency reflectivity performance of conventional geometric transition radar absorbent materials as used typically in anechoic chamber facilities for electromagnetic compatibility testing. The improvement is achieved by the inclusion of impedance-loading elements within the base region of the absorber, and these are implemented in the form of one or more frequency-selective surfaces (FSS). The discussion covers the design of the FSS using computer simulation technology microwave studio, its predicted effect on absorber performance at both normal and oblique incidence, the effect of manufacturing tolerances, and the fabrication and characterization of a prototype-loaded absorber panel. 相似文献
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Cory W. E. Dolle W. C. Milstead F. C. 《Electromagnetic Compatibility, IEEE Transactions on》1965,7(1):64-72
After review of some general properties of RF absorber materials, several of the standard and semistandard techniques for measuring absorber and anechoic chamber quality are discussed. A general purpose RFI laboratory is described together with a simple technique for evaluating the performance of absorber material as it is actually used. An effective background reflectivity of about 4% from 1 - 10 Gc was measured and is believed to be adequate for many applications. 相似文献
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Electromagnetic scattering by pyramidal and wedge absorber 总被引:1,自引:0,他引:1
Electromagnetic scattering from pyramidal and wedge absorbers used to line the walls of modern anechoic chambers is measured and compared with theoretically predicted values. The theoretical performance for various angles of incidence is studied. It is shown that a pyramidal absorber scatters electromagnetic energy more as a random rough surface does. The apparent reflection coefficient from an absorber wall illuminated by a plane wave can be much less than the normal absorber specifications quoted by the manufacturer. For angles near grazing incidence, pyramidal absorbers give a large backscattered field from the pyramid side-faces or edges. The wedge absorber was found to give small backscattered fields for nuclear-grazing incidence. Based on this study, some new guidelines for the design of anechoic chambers are advocated because the specular scattering models used at present do not appear valid for pyramids that are large compared to the wavelength 相似文献
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Baekelandt B. Olyslager F. De Zutter D. 《Electromagnetic Compatibility, IEEE Transactions on》1999,41(4):354-360
Large-size electromagnetic absorbers are mainly used in anechoic and semi-anechoic chambers for electromagnetic compatibility testing. Therefore, the determination of the reflectivities in the low-frequency range (30-300 MHz) are of paramount importance in the performance evaluation of the absorber and, finally, in a “dark room” design. We here present a low-frequency approximation of the reflectivity based on a boundary and surface integral equation technique. This approach makes it possible to compare the approximation to the rigorous integral equation approach and to other approximations in the literature. The validity of the new low-frequency approximation is discussed based on reflectivity calculations of representative two- (2-D) and three-dimensional (3-D) absorber structures 相似文献
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The electromagnetic field characteristics and plane-wave generating ability of a parallel four-wire anechoic chamber which is to be operated in the VHF range is analyzed. The analysis considers three cases: the first is a four-wire chamber when only a thin layer of absorber material covers the chamber walls, the second is a four-wire chamber when only free space surrounds the four wires of the system, and the third is a four-wire chamber when a thick layer of absorber material covers the anechoic chamber walls. The three cases are analyzed by a variety of mathematical methods including the method of moments, waveguide theory, and a finite-difference time-domain method. Numerical results for the propagation constants and electromagnetic fields that are generated in the chamber in the three cases are presented 相似文献
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Yang C.-F. Burnside W.D. Rudduck R.C. 《Antennas and Propagation, IEEE Transactions on》1993,41(5):600-609
A periodic moment-method solution for scattering from a doubly periodic array of lossy dielectric bodies is developed. The purpose is to design electromagnetic wedge and pyramidal absorbers for low reflectivity so that one can improve the performance of anechoic chamber measurements. The spectral-domain formulation and the moment-method volume polarization current approach are used to obtain the expressions for determining the scattering from a doubly periodic array of lossy dielectric bodies. Some wedge and pyramidal absorber configurations that have been designed, fabricated, and tested in the OSU/ESL compact range measurement facility are presented. By taking into account the complexity of real-world material structures, good agreement between calculations and measurements has been obtained 相似文献