EMC场地确认国际标准动态及测试案例

介绍了EMC场地确认的各项关键指标、考核实质及定期验证建议,并依据各项指标对应的最新版标准说明归一化场地衰减及场均匀性测试的标准最新动态及当前国际上相关的研究工作,同时对实际测试中NSA影响因子和不理想场地确认案例进行分析,总结了场地确认的研究意义及对工程师能力要求。     

基于天线方向图的EMC场地确认研究

通过对天线增益、天线系数与天线方向图相关参数的公式推算及EMC场地确认测试考核实质的说明,定性地分析了天线方向图对两项场地确认指标——归一化场地衰减和场地电压驻波比的影响,并得出一些经验性的结论,作为理论分析及实际测试时理解和应用的辅助分析手段。     

用于30MHz～1GHz电磁辐射骚扰测量的全电波暗室场地校验方法

详细介绍了最新国际标准CISPR16-1-4∶2004第5.8条给出的两种评估方法—场地参考法(sitereferencemethod)和归一化场地衰减法NSA。为评估全电波暗室的性能提供重要技术依据。     

用于30MHz～1GHiz电磁辐射骚扰测量的全电波暗室场地校验方法

详细介绍了最新国际标准CISPR 16-1-4:2004第5.8条给出的两种评估方法-场地参考法(site reference method)和归一化场地衰减法NSA.为评估全电波暗室的性能提供重要技术依据.     

仿真暗室归一化场地衰减理论值计算

国际电磁兼容标准给出了标准距离的归一化场地衰减(NSA)的理论值,但在实际应用中需要知道非标准距离的理论值。根据归一化场地衰减的定义,介绍了一种NSA理论值计算模型。对该模型进行了数学推导,得出了NSA的计算公式,并通过计算机编程进行了计算。计算结果表明:计算误差小于0.1dB,满足标准要求。该模型可以用于仿真暗室中不同测试距离、不同收发天线高度的NSA理论值计算。     

基于系统平均转换系数的全电波暗室系统确认

介绍了IEC 61000-4-22中采用的基于系统平均转换系数的全电波暗室测试系统的确认方法,并与CISPR 16-1-4所采用的自由空间归一化场地衰减及场地电压驻波比(site-VSWR)等场地确认的方法做了相应的对比分析。     

NSA理论值的计算方法

介绍了电磁兼容测试场地归一化场地衰减理论值的计算方法，可用于不同测试条件下ＮＳＡ理论值的计算。计算结果与ＣＩＳＰＲ出版物１６－１中给出的标准值之差不大于０．１ｄＢ。     

归一化场地衰减的计算与测量

本文作者简要介绍了归一化场地衰减的理论计算方法,并给出了理想状态下3米法的NSA理论值,详细叙述了NSA的测量方法,并结合某电波暗室的NSA测量,给出实际测量数据.     

5m法全电波暗室射频性能评测方法及影响因素分析

本文介绍了5m法全电波暗室的射频性能评测指标,并结合实际建设情况,分别阐述了归一化场地衰减（NSA）、场地电压驻波比（SVSWR）、场地均匀性（FU）和背景噪声这四项指标的校验和评估方法,并对评测过程中对结果造成影响的因素进行了分析。     

CISPR 16-1-4:2010+A1:2012新增场地验证替代方法

正2012年7月11日,CISPR出版了CISPR 16-1-4的最新修订版(ed.3.1),该修订版中主要引入了一种替代归一化场地衰减(NSA)场地验证方法---参考场地法(RSM)。其实早已有委员在CISPR A中提出采用该方法,只是某些国家一直不赞成实施此方法,所以该替代方法直到今年才列入标准中。由于引入了RSM,该修订版标准的主要改动集中在了标准的第五部分,其他部分仅涉及到了一些定义     

电波暗室性能指标的测试方法

介绍了评估电波暗室性能的方法,包括屏蔽效能、归一化场地衰减、传输损耗、场均匀性的详细测试过程,并对可能影响测试结果的因素和需要注意的问题进行了分析.     

NSA理论值的计算误差

定量地分析了采用３ｍ法测量，计算ＮＳＡ（归一化场地衰减）理论值时引入的误差，并为减小这些计算误差提出了一些具体的建议和方法。     

全电波暗室30MHz～1GHz场地确认方法

该文介绍了全电波暗室30MHz～1GHz场地确认的方法,并对本单位5m全电波暗室的实际测试结果进行了分析总结。     

A New Method of Calculating 3-Meter Site Attenuation

A new method of calculating 3-m site attenuation is described. To obtain an accurate site-attenuation curve, the problem of coupling between antennas is formulated in the form of coupled integral equations for the antenna currents, and solved by the method of moments (MOM). The site-attenuation curve thus obtained shows about 1.3-dB larger attenuation than that given in an IEC document. The deviations in the site-attenuation curve due to the impedance mismatch between the coaxial cable and the measuring equipment, and the influence of the antenna conductor radius on the attenuation curve are also considered. Finally, the calculated site attenuation is compared with the measured attenuation data available in the literature.     

Site diversity gain at the equator: radar‐derived results modeling in Singapore

Site diversity is an effective rain attenuation mitigation technique, especially in the tropical region where high rainfall rates are common. According to our previous study, site diversity gain is found to be dependent on the site separation distance and path elevation angle while it is independent of signal frequency, baseline angle and polarization angle. Therefore, using 28 months of radar data, a simple site diversity gain prediction model is proposed. The proposed model is compared with the existing ITU‐R models. The seasonal wind direction, another factor that might affect the site diversity gain prediction model, is shown to have negligible effect on site diversity gain. Triple‐site diversity is also investigated, and although it is found to provide gain improvement over dual‐site diversity, this gain improvement is too little to justify for the cost of setting up an additional site. This study is useful for the implementation of site diversity as a rain attenuation mitigation technique in the tropical region. Copyright © 2014 John Wiley & Sons, Ltd.     

雷达阵地现场优化模糊综合评估方法研究

针对雷达阵地现场优化效果缺乏系统有效的评估方法的问题,运用了模糊综合评估方法对雷达阵地现场优化进行综合评估。在建立了合理的因素集、评价集、权重集以及根据构建的隶属度函数确定的单因素评价矩阵的基础上,利用模糊数学层次分析法,首次提出并完成了雷达阵地现场优化的模糊综合评判。最后结合空管雷达阵地现场优化具体情况给出算例分析,并对该评估方法作了简要分析。结果表明,该模糊综合评判方法简单、实用、可行,对雷达阵地现场优化和评估具有重要的参考价值。     

Evaluation of 3-N Site Attenuation by the Moment Method

The 3-m site attenuation is calculated by the moment method for vertically polarized waves from 76 to 1000 MHz as well as for horizontally polarized waves from 30 to 1000 MHz, using the specifications outlined by the CISPR and the FCC. The moment method offers a newer more precise treatment of the incident angle to the ground when applied to the theoretical analysis of site attenuation. Calculations are carried out for two kinds of ground conditions. One assumes a metal ground plane (ideally perfect conductor) and the other, a natural earth ground (medium dry). The electrical characteristics of the ground presented in the CCIR Recommendation [15] are adopted for these calculations. Experimental values obtained on a natural earth ground plane using commercial tuned-dipole antennas showed agreement with theoretical values within ± 3 dB.     

An Analysis of Conditional Site Diversity: A Study at Ka-Band

The use of EHF and SHF frequencies above 20 GHz is becoming increasingly important for high-capacity communication systems. Whether these systems are slant-path links, terrestrial fixed links, or deep-space links, the high bandwidths available and the relatively low spectral congestion are very attractive. One of the main disadvantages of these frequency bands is that the attenuation caused by meteorological effects can become significant, and the attenuation caused by clouds, rain, and atmospheric gases becomes very large. The largest attenuation events are caused by rain and clouds with a high liquid water content. In order to provide high-availability links, it is possible to use site diversity, by providing two spatially independent terminals. The spatial separation of the terminals reduces the probability of both terminals being faded. In this paper, we present an analysis of two spatially unique measurements of a satellite-based 20.7-GHz beacon. The results show that even at modest separations there is still the opportunity for significant availability improvements using site diversity. The probability density functions (pdfs) conditioned on the single-site attenuation level are presented. These demonstrate a characteristic shape and could form the basis of future modeling approaches.