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Two models describing properties of the thermal noise power emerging from an antenna mounted in a reverberation chamber are described. The first compares the reverberation chamber to an over-moded cavity acting as a black-body source; the second describes the noise in terms of the antenna noise temperature. Measurements based on the antenna noise temperature model show the noise power to be dependent on the position of the rotating mechanical stirrer. The correlation of the antenna noise temperature with the stirrer position dependent antenna mis-match factor is shown. When a signal is injected into the chamber measurements of the signal to noise power ratio show that this ratio is dependent on the stirrer position and also the position of the signal source within the chamber. These results have significant consequences for the detection of weak signals from radiating sources in a reverberation chamber.

Stochastic electromagnetic fields coupling to printed circuit board (PCB) traces are important to the understanding of electromagnetic compatibility at high frequencies when the circuits or systems are electrically large. In this article, it is studied both numerically and analytically, and the factors affecting the absorbed power are investigated. We present new methods to determine the level of coupling on PCB traces or other transmission lines on a dielectric substrate. A Monte Carlo method is applied to generate random uniform fields, and the quasi-TEM transmission line model is employed to compute the response of the trace for each plane wave numerically. In the analytical method, the closed-form expressions of the zero-order and the first-order approximations are established for the PCB trace. Based on the first-order approximation method and the numerical results, a computationally efficient empirical method is developed to estimate the power received. The absorbed power increases with frequency in the electrically short case after which multiple resonances can be seen. The absorbed power in the matched case is neither the largest nor the smallest among all the cases. It increases with the square of the substrate height but decreases with the permittivity of the substrate.

Ponencia presentada a las IV Jornadas Españolas de EMC - Compatibilidad electromagnética. Organizadas por NAITEC y el Institute of Smart Cities de la Universidad Pública de Navarra. Pamplona, 19-21 de noviembre de 2018

The contents of an equipment enclosure, particularly printed circuit boards (PCBs), affect the enclosure’s shielding performance. At high frequencies this absorption can be quantified using the angle of arrival and polarization averaged absorption cross-section (ACS). However, there is no available data on the high-frequency absorption characteristics of modern PCBs. In this study we apply a reverberation chamber to the determination of the average ACS of a large number of printed circuit boards taken from contemporary information and communication technology (ICT) equipment to provide a unique and comprehensive data-set. The ACS was found to range from 4×10-4 –10-2 m2 from 2-20 GHz and different classes of PCB could be identified according to their surface characteristics. The "shadowing effect" of densely packed PCBs was also quantified for a subset of the PCBs. It was found that the ACS of a PCB in the stack was reduced by 20% - 40% compared to its value when isolated. By way of a review of the general power balance analysis of an electrically large populated equipment enclosure in an external environment we show how the acquired data will be useful for future qualification methodologies for ICT enclosures and PCBs.

This paper reports the results of two experimental campaigns aimed at studying the high-frequency response of a raceway containing low voltage power, telephone, and Ethernet cables, to external electromagnetic field illumination. The raceway was tested against HPEM transients inside a GTEM cell and low power fields inside a reverberation chamber (RC). The HPEM tests revealed that the low voltage power cables have the greatest coupling under a hyperband illumination, compared to telephone and Ethernet cables. The RC tests allowed the determination of statistical transfer functions from random incident field configurations into DM voltage in cable loads. The responses were found to be governed by the raceway under test at the lower frequencies (below 1 GHz). Between 0.2-1 GHz, the raceway gives about 10 dB higher coupling than a short patch cable. The difference is even greater at lower frequencies and for shielded cables. In the frequency band 1-3 GHz, little difference was observed between short patch cables and the full raceway, but both were still significantly higher than direct coupling to the measurement card. Beyond 3 GHz, the coupling is clearly dominated by the terminal equipment. The experiments performed in this work provide a better understanding of the expected induced voltages and currents in commercial cable systems when exposed to IEMI-like signals.

Average absorption cross section can be measured in a reverberation chamber with an uncertainty estimated from the number of independent samples of the chamber transfer function taken during the measurement. However, the current uncertainty model does not account the loading effect of the object being measured or the presence of nonstochastic energy in the chamber, as characterized by the Rician K-factor. Here, the uncertainty model for the absorption cross-section measurements has been extended to include both of these effects for the case of stepped mechanical tuning with a paddle and frequency tuning. The extended uncertainty formula has been applied to predict the range over which absorption cross-section measurements can be made with a defined relative uncertainty in a chamber of given geometry, using both simple models for the reverberation chamber and the measured quality-factor and K -factor. The model has been validated using measurements on a set of absorbing cubes of different sizes compared to Mie Series calculation on sphere of equivalent surface area. The extended error model is particularly utile for the design of reverberation chambers and experiments for absorption cross-section measurements across a wide range of application areas.

A measurement methodology for polarization and angle of incidence averaged electromagnetic absorption cross-section using a reverberation chamber is presented. The method is optimized for simultaneous rapid and accurate determination of average absorption cross-section over the frequency range 1–15 GHz, making it suitable for use in human absorption and exposure studies. The typical measurement time of the subject is about 8 min with a corresponding statistical uncertainty of about 3% in the measured absorption cross-section. The method is validated by comparing measurements on a spherical phantom with Mie series calculations. The efficacy of the method is demonstrated with measurements of the posture dependence of the absorption cross-section of a human subject and an investigation of the effects of clothing on the measured absorption which are important considerations for the practical design of experiments for studies on human subjects.

We present broadband reverberation chamber measurements of the absorption cross section (ACS) of the hu- man body averaged over all directions of incidence and angles of polarization. This frequency-dependent parameter characterizes the interactions between the body and the enclosures of rever- berant environments such as aircraft cabins, and is therefore important for the determination of the overall Q-factor and hence the field strength illuminating equipment inside such en- closures. It also correlates directly with the electromagnetic expo- sure of occupants of reverberant environments. The average absorption cross section of nine subjects was measured at fre- quencies over the range 1-8.5 GHz. For a 75 kg male the ACS varied between 0.18 and 0.45 square meters over this range. ACS also correlated with body surface area for the subjects tested. The results agree well with computational electromagnetic simu- lations, but are obtained much more rapidly. We have used the obtained values of absorption cross section to estimate the effect of passengers on the Q-factor of a typical airliner cabin. Index Terms—reverberation chamber, absorption cross

The current method of obtaining a Shielding Effectiveness (SE) measurement involves field measurements both inside and outside the enclosure to be tested. In this paper, a relationship between the Shielding Effectiveness and the Q-factor of the enclosure under test (EUT) is investigated. Measurements are made in an anechoic chamber to obtain the Q-factor using a method previously detailed and to assess the Shielding Effectiveness of the enclosure under test. A relationship between Q-factor and shielding effectiveness is shown, and possible uses of this relationship are discussed.

This paper presents a transmission line model (TLM) for the GSM base station lightning transient analysis, which is based on the use of the well-known ATP-EMTP software package. Direct lightning strike to the GSM base station tower is modelled with the Heidler's type of surge current source. The earthing grid and the GSM base station's tower structure by circular cross section conductors are approximated. In numerical model, conductors are subdivided into segments (1D finite elements) and Clark's model with distributed parameters is used. Because of limitations of ATP-EMTP software package, the leakage resistance of buried segments is modelled as lumped parameter. Analytical expressions for distributed and lumped segment parameters are derived using the average potential method.

The response surface methodology (RSM) for modelling IC packages is presented. The segmentation of the lead frame of an IC package into simpler structures is applied in order to describe the package. The result of the segmentation is the lead frame described by using only two types of simplified lead frame model primitives. These simplified models are subject to the 2q experiment, i.e. a set of electromagnetic (EM) simulations is performed. Each EM simulation is done on the simplified lead frame structure. The per-unit-length (p.u.l.) parameters of the lumped element model are obtained by fitting the p.u.l. parameters to the S-parameters obtained by EM simulations. These extracted lumped element parameters depend on the geometrical data of the package and they are approximated by the RSM methodology. The final results of the presented methodology are the parameters of the lumped element model described by using closed-form equations that depend on the geometrical data as the input variables. These equations can be used to model the lead frames having different geometries and to help avoid time consuming EM simulations and subsequent parameter extraction. The presented methodology is demonstrated on the TQFP100 and SOIC14 lead frames.