共查询到19条相似文献,搜索用时 115 毫秒
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提出了基于镜像对称的多馈源混响室扩展方法,给出了镜像对称扩展混响室改善工作区域场性能的原理,对单混响室及镜像混响室模型进行数值模拟计算,并设计了3组仿真实验从场强大小和场均匀性两个方面验证镜像混响室改善工作区域场性能的可行性.实验结果表明:单混响室镜像对称组合扩展后,在成倍扩展混响室及工作区域体积的同时,工作区域场强增大,场均匀性有所提高,解决了混响室体积扩展与场强减小以及变频场均匀性恶化的矛盾;通过发射天线同时馈入相同功率即多个小功放合成的方法解决了混响室高场强问题,降低对功率放大器的要求,进而降低混响室的测试成本. 相似文献
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混响室桨叶夹角对场均匀性影响的仿真及测量 总被引:2,自引:0,他引:2
用HFSS10.0对混响室进行仿真,研究了搅拌器的夹角对场均匀性的影响。首先阐述了混响室的特点及其场均匀性校准的原理和方法,然后根据实际混响室的尺寸,用HFSS10.0进行建模,通过仿真得出搅拌器在不同夹角情况下的场均匀性。最后根据仿真结果,对混响室的场均匀性进行测量,验证了合理的设计搅拌器会改善混响室的场均匀性,降低最低可用频率。 相似文献
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针对电场传感器在1 GHz以上频段高于200 V/m场强的校准需求,提出了等效天线系数法.该方法借用了天线系数的概念,在混响室中首先通过现有场强标准装置传递得到小场强时接收天线的等效天线系数,再利用等效天线系数对混响室中的大场强定标,从而实现电场传感器的大场强校准.混响室中采用等效天线系数法定标的大场强与采用统计方法计算得到的大场强相比较,场强偏差满足系统不确定度要求,说明了等效天线系数法的合理性.该方法借助混响室的特点和天线系数概念,将电场传感器校准幅度提升至200 V/m以上,为大场强测量的准确性提供了依据. 相似文献
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为研究混响室搅拌器位置对测试区域场均匀性影响,采用基于矩量法的电磁仿真软件FEKO对混响室仿真模型进行数值计算,通过与遗传算法相结合对混响室搅拌器位置进行优化,得到了搅拌器位置的最优解以及相应的表征混响室测试区域场均匀性的电场标准偏差值.研究表明:搅拌器位置影响测试区域场均匀性,当搅拌器位置处于最优配置时,测试区域各轴向电场标准偏差较初始状态分别下降了47.4%、20.1%、57.1%,总标准偏差下降了44.0%,测试区域场均匀性较优化前有所提高,提高了混响室用于电磁兼容测试时的准确度. 相似文献
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为解决混响室大体积与场性能高要求之间的矛盾,提出了一种基于镜像原理的多馈源混响室的设计思想,从原理上分析了镜像多馈源混响室的可行性和有效性,并通过仿真计算研究了镜像双馈源混响室的场性能.结果表明,在输入功率一定时,两个单混响室系统组合成镜像双馈源混响室后,在工作区域的场均匀性能不下降的基础上,不但可用于电磁兼容测试的工作区域体积大幅度增大,而且测试区域的电场强度也得到了提高.同时,对镜像多馈源混响室进行了进一步的扩展分析,得出了组成镜像多馈源混响室的单混响室系统数量的理论表达式. 相似文献
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In this article, the effect of the size of the antennas on the distribution of the electric field observed in a reverberation chamber is analyzed. Our hypothesis is that the more the antenna is voluminous, the more the behavior of the chamber appears to be ideal through measurement analysis. A simple numerical model is presented and used to verify the phenomenon and give credence to the assumption. 相似文献
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Scattering Cross Section Measurement in Reverberation Chamber 总被引:1,自引:0,他引:1
Reverberation chambers are now common test facilities used in electromagnetic compatibility. Objects loaded in the chambers, such as antennas and reflectors, can affect the measurement because they absorb and scatter the diffuse field. Thus, it is important to know the scattering and absorbing cross sections of these objects. In this paper, we propose a new technique to measure the scattering cross sections averaged over all angles of incidence and both polarizations in a reverberation chamber. It is based on stacking time-dependent fields generated by a repetitive pulsed source while the objects are moving. The fields recorded by wire antennas are averaged over the object positions. The square of the averaged field is shown to decrease exponentially with the time spent by the wave in the chamber. The cross section is deduced from the exponential factor. The technique has been experimentally validated in a 1 m3 reverberation chamber at 2.45 GHz with metallic spheres of several radii. The experimental cross sections are found to be in agreement with the theoretical ones. 相似文献
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MIMO systems are characterized by their maximum available capacity, which is reduced if there is correlation between the signals on different channels. The correlation is primarily caused by mutual coupling between the elements of the antenna arrays on both the receiving and transmitting sides. Similarly, diversity antennas can be characterized by a diversity gain that also is affected by mutual coupling between the antennas. We explain how such MIMO and diversity antennas with mutual coupling can be analyzed by classical embedded element patterns that can be computed by standard computer codes. In the MIMO example under investigation, the mutual coupling reduces both correlation, which increases the capacity, and radiation efficiency, which decreases it, and the combined effect is a net capacity reduction. We also explain how the radiation efficiency, diversity gain, correlation, and channel capacity can be measured in a reverberation chamber. The measurements show good agreement with simulations. 相似文献
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Convergence of the reverberation chambers to the equilibrium analyzed with the finite-difference time-domain algorithm 总被引:1,自引:0,他引:1
Over recent years, reverberation chambers have been analyzed by many numerical techniques. This contribution studies how the finite-difference time-domain algorithm converges to the steady state conditions as a function of the cavity Q factor, changing the wall conductivity or the internal lossy media. By lowering the reflection coefficient of the chamber walls, the computation time could be considerably reduced without a significant effect on the field distribution for any analyzed antennas. The field distributions are strongly correlated when the conductivity of the wall is one hundredth of the copper conductivity or greater, whereas when the conductivity is lower the correlation between field distributions is low. 相似文献
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《Electronics letters》2008,44(17):1002-1003
Using the reverberation chamber to obtain antenna radiation efficiency is considered. The reverberation chamber, which has for many years been used for electromagnetic compatibility measurements, can also be used with great advantage for antenna measurements since it simulates effectively a uniform multipath propagation environment. How a reverberation chamber can be used to measure the ultra-wideband (UWB) antenna efficiency in a very short time is described. The procedure based on time domain is described and some experimental results are given and compared to measurements obtained by the Wheeler cap method extended by Schantz to UWB antennas. 相似文献
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Electronic mode stirring for reverberation chambers 总被引:1,自引:0,他引:1
A modal analysis and a uniform-field approximation are presented for the fields in an idealized two-dimensional, rectangular cavity excited by an electric line source. The model is used to evaluate the effectiveness of frequency stirring, an alternative to mechanical stirring in reverberation chamber immunity measurements. Numerical results indicate that good field uniformity (standard deviation less than 1 dB) can be obtained with a bandwidth of 10 MHz at a center frequency of 4 GHz. The bandwidth requirement is determined primarily by the number of modes excited, and higher frequencies can achieve the same field uniformity with a smaller bandwidth because of the higher mode density. Cavity excitation by two single-frequency sources is also analyzed 相似文献