Random-Walk Technique for Measuring the Electromagnetic Environment in Electrically Large Reflective Spaces

Tait, Gregory B.; Slocum, M.B.

doi:10.1109/tim.2010.2064930

Cited by 21 publications

(24 citation statements)

References 15 publications

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“…Due to other objects present on site or the vicinity of the walls near the immovable apparatus, it is not granted that every position around it is available. Applying the very same method of performing the measurement as in the AC but only at single positions, as recommended by [33], can result in very high errors [66]. The field received by the Rx is a summation of the deterministic LOS component with components scattered unpredictably from the surroundings as shown in Figure 4.2, expected to come from the Rice distribution [69].…”

Section: Ac and Atsmentioning

confidence: 99%

“…Each set of 50 measurements gives only a single maximum and a single average, but in order to perform a statistical analysis, more samples can be obtained by applying the frequency stirring technique [66]. It is commonly used in RC, and allows to increase the amount of obtainable samples.…”

Section: Field Uniformitymentioning

confidence: 99%

“…The frequency stirring was performed in a bandwidth of 50 MHz. The frequency separation of two uncorrelated points is Δ f > f /Q [66], which in case of very low Q-factors in office and workshop environments, is at least 10 MHz and 5 MHz, respectively. However, in order to increase the very low number of samples to a reasonable amount, the data was sampled every 2.5 MHz, giving 20 points per frequency stirring band.…”

Section: Field Uniformitymentioning

confidence: 99%

“…The conventional approach used by many manufacturers of large apparatus is to perform EMI measurements on-site at many places around it, and assuming free space conditions, due to the lack of any alternative. However, the presence of reflections can cause errors in estimating the line of sight component, even if it is dominant over the scattered components [66]. Additionally, due to the many carefully selected measurement positions, it is also a very time-consuming activity.…”

Section: Introductionmentioning

confidence: 99%

“…It has been shown that semi-enclosed environments, e.g. ships, airplanes, or factories, create multipath environments similar in behavior to those of RCs [6], [66], [67], also addressed in Chapter 2 of this thesis. On the other hand, the standard on-site EMC testing, according to [33], is performed by using methods based on OATS or SAC, utilizing the line of sight component.…”

Section: Introductionmentioning

confidence: 99%

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Electromagnetic fields in reverberant environments

Vogt-Ardatjew¹

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SummaryThe phenomenon of resonating electromagnetic (EM) fields has been commonly and successfully exploited in reverberation chambers (RC) for the purpose of electromagnetic compatibility (EMC) testing, as well as modeling multipath environments. An RC is designed to maximize the amount of reflections while minimizing the losses, thus creating a statistically uniform, isotropic, and randomly polarized field. Due to the desired very high complexity of such a field, its description is best done statistically. Although largely successful, the currently used statistical models allow for a certain degree of freedom, especially with regard to defining the extreme field strengths, which are also the main cause of electromagnetic interference (EMI). Furthermore, some actual multipath, enclosed environments such as airplane fuselages, ships, or even building interiors, can unintentionally possess the ability to create enough strong reflections so that the resulting resonating EM field within them resembles the field inside a dedicated RC. Those reverberant environments (RE) can therefore utilize the methods and techniques similar to the ones used in laboratory conditions. Due to the very high complexity and diversity, resulting in increased difficulty of both numerical or analytical description of the REs, the analysis performed throughout this work is mainly experimental. Such an approach allows to bypass the often unreasonable or too generalized assumptions of the available models while utilizing purely empirical data.The initial step made in this thesis focuses on introducing REs as environments sharing multiple aspects of EM field shaping with RCs. The experimental analysis has been performed on two example REs by means of quality factor (Q-factor), insertion loss (IL), as well as goodness of fit (GOF) tests. The results, although highly variable with frequency, indicate a possible similarity to a referential RC analyzed alongside. Furthermore, due to the difficulty of collecting large amounts of data and parameter isolation in the REs, two dedicated chambers: a classical RC and the vibrating intrinsic reverberation chamber (VIRC), have been analyzed as candidates allowing to simulate an RE in laboratory conditions. By the means of Q-factor, k-factor, GOF, as well as number of samples, related to field repeatability, it has been shown that the VIRC provides substantially better conditions for the given purpose.The search of maximum field strengths in reverberant environments has been performed by exploiting the capability of the VIRC to efficiently generate large amounts of independent samples. Performing 1-hour long measurements in the VIRC allows to obtain the desired results with very high repeatability, while giving space for parameter isolation. The first hypothesis states that the maximum-to-average (max/avg) electric field ratio depends on the losses of the environment. The measurement campaign performed to test it consisted of multiple setups with highly spread Q-factors, additionally creating a link between...

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Section: Ac and Atsmentioning

confidence: 99%

Section: Field Uniformitymentioning

confidence: 99%

Section: Field Uniformitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electromagnetic fields in reverberant environments

Vogt-Ardatjew¹

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Probability distributions of three‐antenna efficiency measurement in a reverberation chamber

Xing

Zhao

et al. 2021

IET Microwaves Antenna & Prop

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Analytical expressions are derived for probability distributions of the three-antenna efficiency measurement. The probability density function (PDF), the expected value, and the standard deviation are derived analytically. The Mellin transform is used in the PDF derivation to obtain the product of random variables, and the analytical distributions for the measured antenna efficiency are obtained. Measurements are performed to verify the results, which agree well with the analytical expressions.This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

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Studying the Probability of EMI through Time-Variance Behavior of Environment on Medical Devices

Das

Vogt-Ardatjew

Berg³

et al. 2021

2021 Asia-Pacific International Symposium on Electromagnetic Compatibility (APEMC)

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Various studies have been conducted to monitor the electromagnetic (EM) environment of the hospital, where an emitter is mounted near medical devices. They placed their antenna in a specific area to test the maximum amplitude of power obtained by the antenna as well as explore the environment without identifying the time-variance behavior. The main goal of this paper is to observe the time-variance behavior of the emitters over the course of a 24-hour period when a receiving antenna is installed in a room and the effect they have on the EM environment. It will provide the probability of EMI from the perspective of the emitters, which will help to use it further for the risk-based EMC approach. In this paper, the discussion about the different types of time-variance behavior is done with examples, statistically explained the results.

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Random-Walk Technique for Measuring the Electromagnetic Environment in Electrically Large Reflective Spaces

Cited by 21 publications

References 15 publications

Electromagnetic fields in reverberant environments

Electromagnetic fields in reverberant environments

Probability distributions of three‐antenna efficiency measurement in a reverberation chamber

Studying the Probability of EMI through Time-Variance Behavior of Environment on Medical Devices

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