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0引言:为什么要测量微波暗室的剩余互调微波暗室分为全电波暗室和半电波暗室。全电波暗室定义为六面装有吸波材料的屏蔽室,用于模拟自由空间;半电波暗室则是五面装有吸波材料,地面为反射面,用于模拟开阔场。常见的微波暗室的墙体由铁氧体材料加微波吸波材料组成。和其他无源器件一样,微波暗室也遵循互调产生的机理。在大功率多载频的作用下,微波暗室的墙体(铁氧体和吸波材料)会产生互调。在天线的无源互调测试中,如果微波暗室自身的互调大于被测天线的互调或能与之相比拟,则会影响天线互调的测试精度。因此,我们将微波暗室(为天线互调测量提供环境)自身的无源互调产物称为剩余互调。 相似文献
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为了有效预测微波暗室的静区性能,使用FEKO软件进行任意入射角度条件下角锥吸波材料的前向反射率仿真,并以某矩形暗室结构为例,利用吸波材料反射率仿真结果,采用射线追踪法计算了发射天线位于天线阵面上典型位置时暗室静区内反射电平的分布情况.经比较,仿真结果与实际测量结果一致性较好,该方法为微波暗室性能预测提供了有效手段. 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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双喇叭微波暗室不但包含有锥形暗室和矩形暗室的特征和优点,而且建造这样的暗室能减少吸波材料和暗室建筑费用15%。柱型暗室具有独特的用途,对称性好,电磁静区的性能也比矩型暗室优良。 相似文献
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大型微波暗室电磁特性的理论分析与设计 总被引:4,自引:0,他引:4
利用几何光学法和物理光学法,分析了带有双柱面紧缩场天线的微波暗室内的电磁场分布。通过计算得到了满足指定性能要求的暗室墙壁上吸波材料的吸波性能分布,以及暗室各墙壁上的总反射场强分布。 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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作为电磁兼容测试场地,半电波暗室越来越显示出其重要性.介绍了半电波暗室的基本设计方法,并举例介绍了射线法技术,给出了10m法半电波暗室的设计结果. 相似文献
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Togawa H. Hatakeyama K. Yamauchi K. 《Electromagnetic Compatibility, IEEE Transactions on》2005,47(2):312-319
A voltage standing-wave ratio (VSWR) measurement method and ensuing reflectivity characteristics are presented for anechoic chambers in the range 1-76.5 GHz. The free space VSWR measurements are performed using a composite antenna technique. By making use of two different anechoic chambers, the dependency of the reflectivity characteristics upon direction in the horizontal plane and absorber's height is analyzed. 相似文献
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Correlate measurements at different test sites 总被引:1,自引:0,他引:1
Fourestie B. Altman Z. Wiart J. Azoulay A. 《Antennas and Propagation, IEEE Transactions on》1999,47(10):1569-1573
A new method for systematic correlation of measurements in semi-anechoic and anechoic chambers is presented. A signal measured in a semi-anechoic chamber is first processed using the matrix-pencil method which is applied sequentially on small frequency intervals. On each interval the measured signal is decomposed into its propagating wave components. The component corresponding to the wave reflected from the ground is identified and removed to fully retrieve the signal measured in an anechoic chamber. Three examples using log-periodic and Vivaldi antennas in different anechoic and semi-anechoic chambers for varying frequency ranges illustrate the method. The proposed decomposition algorithm can be utilized to characterize measurement test site imperfections 相似文献
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给出了天线方向图比较法和自由空间电压驻波比法两者的对照,这2种方法可用于评估无线电吸波暗室的反射电平。在分析这2种方法之后,指出了哪些参数会影响反射电平的测量值。通过实验结果的对照,揭示了为什么在采用这2种方法时会得到不尽一致和不相关联的结果,进而还表明当吸波暗室性能获得改进之后,如何利用反射电平来衡量这种改进。基于目前的研究成果,描述了吸波暗室性能的评估步骤。同时,还通过举例指出有必要开展进一步的研究,以便归纳出满意的评估步骤。 相似文献
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从暗室使用者的角度,结合暗室的测试功能、无反射特性、屏蔽效能、测量设备和测量方法等方面,以举例的方式,介绍一些暗室概念设计的思路和方法,以期暗室建成后的性能能达到初始期望的要求。 相似文献
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给出了天线方向图比较法和自由空间电压驻波比法两者的对照,这2种方法可用于评估无线电吸波暗室的反射电平。在分析这2种方法之后,指出了哪些参数会影响反射电平的测量值。通过实验结果的对照,揭示了为什么在采用这2种方法时会得到不尽一致和不相关联的结果,进而还表明当吸波暗室性能获得改进之后,如何利用反射电平来衡量这种改进。基于目前的研究成果,描述了吸波暗室性能的评估步骤。同时,还通过举例指出有必要开展进一步的研究,以便归纳出满意的评估步骤。 相似文献
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A comparison between the antenna-pattern comparison technique and the free-space voltage standing-wave ratio technique for evaluating the reflectivity level of radio anechoic chambers is presented. Based on an analysis of the two techniques, it is pointed out which parameters influence the measured value of the reflectivity level. The comparison is illustrated with experimental results and it is explained why inconsistent and uncorrelated results may be found when the two methods are used. Furthermore, it is demonstrated, by introducing improvements in a chamber, how the reflectivity level can be used to measure the improvements. This work is inspired by the current discussion of finding a figure of merit for anechoic chambers. Based on the results, an evaluation procedure for anechoic chambers is indicated. However, it is pointed out and illustrated by examples that further investigations are necessary before a satisfactory procedure can be outlined. 相似文献
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In a previous paper we have presented a method for evaluating the performance of anechoic chambers by analyzing the S-parameters of a system comprising two antennas facing each other in an anechoic chamber using the matrix pencil method. In this work, we present an improvement of this resonance detection technique using only the transmission parameter S21. The propagating components of the transmission parameter S21 are derived over small frequency intervals using the matrix pencil method and then removed from S21 in a two-level decomposition procedure. The resonances are clearly identified from the residual signal. Two examples of resonance detection in two different anechoic chambers illustrate the proposed method 相似文献
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A W Guy 《The Journal of microwave power》1979,14(4):327-338
A system of miniature anechoic chambers for chronically exposing a sizeable number of animals to microwave radiation was developed in which each animal can be individually exposed to microwaves or sham-exposed under controlled environmental conditions. Each animal is supplied with food and water by means designed to eliminate undesirable perturbations of the field. Field patterns in each chamber correspond closely to those made in large anechoic chambers; measurements indicate that a power density of 169 microW/cm2 per watt of input power can be provided, which results in peak SAR levels of 0.37 W/kg in cadavers of exposed rats. 相似文献