ALBERT

Description: A very efficient boundary-element method for the calculation of the quasi-static port inductances of vertical interconnections within parallel-plate structures is developed. It requires only a one-dimensional discretization along the contour of the plate pair and can be applied to arbitrary geometries. The algorithm is validated by the exact analytical solution for the circular geometry. The low-frequency response of an arbitrary multiport structure can be directly analyzed by the coupled port-inductance network together with the plate capacitance. As examples a circular-shaped and two irregularly shaped plane pairs are considered. The comparison with exact analytical solutions and three-dimensional-full-wave field simulation shows a very good agreement.

Description: The leader progression model (LPM) is a tool for estimating the lightning performance of transmission lines. However, the large computation time remains a problem for the engineering application of this model. An analytical method is proposed in this paper to mitigate the aforementioned problem. First, nonlinear trajectory equations describing the movement of upward and downward leaders are obtained, starting with differential equations. Based on the trajectory equations, the average electric field between the upward and downward leader tips is represented with a comprehensive nonlinear equation. The final strike point is determined by solving the equations. Results show that the proposed method effectively mitigates the large computation time problem of traditional (numerical) LPM.

Description: Principal component analysis (PCA) and independent component analysis (ICA) for radiated emissions from printed circuits are critically intercompared, revealing similarities and differences of the extracted components between both methods. The input data in this analysis are measured wideband complex-valued magnetic radiated and evanescent fields with quasi-Gaussian spatial distributions. PCA and ICA lead to similar maps of their components when considered as spatial eigenmodes, but independent components exhibit simpler field structure than principal components.

Description: Closed-form expressions for the approximation of frequency variations of per-unit-length resistance and inductance of microstrip transmission lines are presented. The provided expressions guarantee causality of the time-domain response. They are valid from dc up to the highest frequencies for which the quasi-static analysis of microstrip transmission lines is applicable. Additionally, the expressions take into account the finite width of the ground plane and can deal with a broad range of dimensions of microstrip lines. The correctness of the formulas is experimentally verified.

Description: This paper investigates the convergence and error evaluation of the distributed analytical representation and iterative technique (DARIT-field) which is a new approach for the analysis of field coupling to multiconductor transmission lines. The DARIT-field method has the advantage of high computational efficiency over the other methods. In order to know the convergence speed and the error at each iteration step of DARIT-field, an analytic expression of iterative error is derived by combining the two telegrapher's equations into a matrix equation and using the euclidean norm to explore its upper bound. The expression shows that the convergence speed is mainly influenced by three parameters, namely coupling factor (CF), terminal loads, and the line length to excitation field wavelength ratio $(d/lambda)$ . The convergence speed is a function of CF, terminal loads, and the line length to excitation field wavelength ratio $(d/lambda)$ . These results allow the users to make a compromise between computational cost and accuracy by selecting the number of iterations.

Description: This paper presents an efficient evaluation method for multiconductor transmission lines with random translation over an infinite and perfectly conducting ground under a plane wave. Based on the assumption of small translation quantity, the equations for the estimation of average induced voltage, induced voltage variation, and the probability distribution of the voltage variation are derived. The average induced voltages and the probability distribution of the voltage variation estimated by the proposed method are in a good agreement with those via the Monte Carlo method but the proposed method is more efficient. The relative sensitivity of the induced voltage to the height approximately equals the inverse of the line height, which can be applied to evaluate the influence induced by the random translation of the line quickly, especially in the low frequency range.

Description: A passive and inherently stable multiport equivalent circuit for lossy transmission lines is presented. The convergence of the infinite modal representation is accelerated by appropriate inductances, for which an exact closed-form expression is developed. The order number of the truncated modal circuit is estimated by a simple relation, according to the required signal bandwidth. The coupling of arbitrary external electromagnetic fields is incorporated by a limited number of corresponding modal sources. The accuracy and versatility of the suggested SPICE-compatible equivalent circuit is demonstrated by examples in frequency and time-domain, including nonlinear terminations.

Description: Carson's, Pollaczek's, Wise's, and Sunde's earth-return impedances of an overhead line have been examined, and errors involved in the formulas are explained. Modified Pollaczek's and Carson's/Sunde's formulas are described. Wave propagation characteristics on a multiconductor in a high-frequency region are evaluated by adopting the modified earth-return impedance and Wise's earth-return admittance. Sommerfeld–Goubau propagation in a high-frequency region, which shows transition between transverse electromagnetic and transverse magnetic propagation, has been confirmed in the calculated results which agree with those predicted by Kikuchi for a single conductor. On a multiconductor system, it is found that the aerial mode also shows Sommerfeld–Goubau propagation when the separation between conductors is large and the earth resistivity is high.

Description: This paper deals with the electromagnetic interaction of a straight thin wire located inside a cylinder with the cylinder walls. The wire runs parallel to the cylinder axis and connects its two opposite caps. A lumped source is chosen, which feeds the terminated conductor. For this configuration, an exact analytical solution for the induced current on the conductor is presented. On the basis of a two-sum Green's function expressed in cylindrical coordinates, the current is derived from the boundary conditions for the total electrical field on the surface of the conductor and the Fourier expansion series for the unknown current and the (known) exciting electrical field. The obtained analytical results are compared to those obtained from a full-wave method and show excellent agreement. They clearly document that the electromagnetic interaction between the cylinder and wire can strongly influence the shape of the transmitted signal. In particular, at higher frequencies, more and more resonance frequencies of the cylinder occur in the current spectrum. Therefore, the application of classical transmission-line theory on conductors, which are housed in resonators, is not allowed in general.

Description: The aim of this paper is the definition of an equivalent two-port model of a transmission line that is able to take into account high frequency radiation effects. Such a model is particularly useful when one has to represent the line into a more complex power system, modeled in a lumped way. To reach this goal, it is necessary to produce a reliable and computationally effective solution to the problem of the high-frequency electromagnetic field coupling with a terminated transmission line. From a mathematical standpoint, this problem can be presented by means of an integral equation whose solution can be achieved with regularization procedures for linear inverse problems. In order to obtain a computationally efficient result, the unknown current is first developed in a Fourier series and then the Landweber iterative algorithm is applied to identify the series coefficients. The proposed method is then tested taking as reference the numerical results obtained using the Numerical Electromagnetics Code (NEC-2), reaching a good agreement.

Description: Mixed carbon nanotube bundles (MCBs) are considered to be highly potential interconnect solutions in the current nanoscale regime. Different MCBs with random and spatial arrangements are proposed based on the placements of single- and multiwalled carbon nanotubes (CNTs) (SWNTs and MWNTs) in a bundle. Propagation delay and dynamic crosstalk performances are analyzed using the modified equivalent single conductor model of proposed MCB topologies. Encouragingly, a significant reduction in propagation delay and crosstalk delay is observed for a spatial arrangement of an MCB wherein MWNTs are placed peripherally to the centrally located SWNTs. Typically, the average delay with and without crosstalk is improved by 82.8% and 80%, respectively, compared to the MCB having randomly distributed SWNTs and MWNTs.

Description: The continuous increase of the operating frequency and density of integrated circuits leads to consider single-wall carbon nanotubes (SWCNTs) and multiwall carbon nanotubes (MWCNTs) as the most promising candidates for future interconnect technology because of their high current-carrying capacity and conductivity in the nanoscale, and immunity to electromigration. Several modeling methods for SWCNT and MWCNT interconnects have been based on the multiconductor transmission line (MTL) theory. These methods are limited to nanostructures with predefined values of electrical and geometrical parameters. Since process technology continues to scale downward and physical interconnect dimensions become smaller, the impact of design parameters (e.g., layout features) on the system behavior has to be carefully investigated for a successful design by performing design space exploration, optimization, and variability analysis. These design activities require multiple system simulations for different values of design parameters, and using MTL-based solvers is not an efficient choice. Parametric macromodels can be used to accurately and efficiently model these parameter effects, avoiding the brute-force use of MTL-based solvers.

Description: As the key devices of an HVDC transmission system, converter valves should bear different forms of overvoltage. Additionally, the wideband frequency electromagnetic noises caused by the switching of thyristor may impact the normal operation of the communication and control systems in an HVDC converter substation. Consequently, it is of great significance to build the model that is suitable for wide frequency range for the key components of converter valve system. Based on the elementary wideband model, the integrated wideband model is proposed and the estimation method for corresponding parameters is also addressed for different kinds of components in this paper. The theoretical analysis and simulation results show that the integrated wideband model has high accuracy and simplicity; it also can provide the results with rigorous passivity and specific physical meaning. As for the application, the proposed method is used to model the key components of an HVDC converter valve and proved to be correct and effective.

Description: The paper discusses the effect of frequency dependence of soil electrical parameters (also called soil dispersion) on lightning currents induced on the shield of buried cables. To this aim, a full-wave approach based on the finite element method is used in which soil dispersion is incorporated into the model using available analytical formulae obtained from experimental data. It is shown that the soil dispersion can affect the induced currents only for soils with very low conductivities ( $leq 0.003, {rm S/m}$ ). It is also shown that, depending on the burial depth of the cable, for poorly conducting soils with conductivities lower than 0.0005 S/m or so, the soil dispersion can result either in an increase or in a decrease of the induced current peak.

Description: This study evaluates the immunity of a low-noise amplifier (LNA) using a transient voltage suppressor (TVS) diode under direct current injection high-power microwave (HPM) pulses. The ac behavior of the TVS diode is examined. Both experiments and analysis demonstrate that the injected HPM power to failure of the LNA is increased by a factor of about 6 through the introduction of a TVS diode, the power to failure of the LNA is also related to the proportion of the direct current injected into the TVS diode and LNA. This analysis is useful for further discussion regarding semiconductor protection under HPM pulses.

Description: Many studies were devoted to the analysis and the detection of electromagnetic attacks against critical electronic systems at the system or the component levels. Some attempts have been made to correlate effects scenarios with events logged by the kernel of the operating system (OS) of commercial-off-the-shelf computer running Windows. Due to the closed principle of the last OS, we decided to perform such an analysis on a computer running a Linux distribution in which a complete access to logs is available. It will be demonstrated that a computer running such an open OS allows detecting the perturbations induced by intentional electromagnetic interferences at different levels of the targeted computer.

Description: The objective of this paper is to present a methodology for identifying the current flow in the capacitors of a multiphase buck converter by synchronously measuring the capacitor currents. A multiphase buck converter uses multiple parallel buck converters with different switching times to source a large amount of current. Currents in the primary capacitors of a multiphase buck converter are drawn by all phases of the converter; however, the phases switch asynchronously. Synchronizing to the switching of a specific phase reveals how the current from that phase is distributed among the capacitors throughout a circuit board. The proposed measurement method is illustrated by comparing an initial printed circuit board design to a new design to show the effect of better capacitor placement and the addition of a ground plane. The new design confines the phase currents to the capacitors close to the field effect transistors of the specific phase.

Description: Research and development are currently being performed to transform the US's utility electric grid into a “smart grid [1] , [2] .” Smart meters are among the first intelligent metering devices used within the “smart grid” concept. They have been deployed in thousands of commercial and residential electrical installations around the US [3] , [4] . While the wide-scale deployment of these devices has initially proven very successful, there is still much that is unknown about how they will impact the long-term operation of a large utility grid or the electrical devices sourced by them [5] . One such device, whose operation appears to be impacted by the smart meter, under specific conditions, is a ground-fault circuit interrupter (GFCI). It has been reported that the RF transmissions from smart meters can induce false tripping events on GFCI outlets installed on temporary construction poles. In an effort to understand why this may happen, a research study, which is presented here, has been performed to understand the correlation between RF transmissions and GFCI tripping events on construction poles.

Description: A locating system based on an advanced time difference of arrival (TDOA) estimation method is developed to locate the position of a discharge source to avoid pulsed electromagnetic interference (PEMI) with the surrounding radio communication environment. In general, from the waveforms of PEMI waves received by an antenna array, the source position can be located or the direction of arrival (DOA) of the EM waves can be estimated by applying TDOA-based methods. However, owing to noises and multipath waves that occur at the metal surfaces of electric power equipment, the estimation accuracy of the TDOA may decrease, and the location accuracy will be degraded. To improve the accuracy of TDOA estimation, we propose a new TDOA estimation technique. In our developed locating system, PEMI waves are received by a four-antenna-square array and the DOA is estimated from the TDOA, which is estimated using the generalized cross-correlation phase transform method in combination with the proposed technique. A PEMI source is ultimately located by aiming a charge-coupled device camera, installed at the center of the antenna array, at the estimated DOA. The estimation accuracy of the locating system is evaluated through experimental measurements. The results show that the developed locating system can locate the position of a PEMI source existing within about 30 m from the system with high accuracy.

Description: High-frequency signals on interconnects can cause significant radiated electromagnetic emissions. An intermediate level modeling method aimed at providing a faster solution with less computing resources to allow designers to obtain rapid approximations is desirable. This paper presents a modeling technique to speed up the evaluation of radiated fields from interconnect cables. Based on the Hertzian dipole radiation theory and transmission-line frequency-dependant solutions, the radiating source is modeled by the sum of a large number of short dipoles. This model allows the contributions of line-end discontinuities to be included through a vector network analyzer measurement together with a monopole approximation. The proposed method is verified by open-line and RG 58 coaxial cable measurements.

Description: An efficient approach to achieve the shielding effectiveness (SE) by using a frequency-selective surface (FSS) is presented. This FSS, which consists of cross dipoles and rings printed on the opposite sides of a single-layer FR-4 substrate, exhibits a wide, 7.5-GHz stopband to provide simultaneous shielding in both X- and Ka-bands. Experimental results confirm SE of the prototype over an ultra-wide band with more than 20-dB measured attenuation. The design is compact and suitable to provide shielding against the radiation interference caused by license-free and other radio systems.

Description: The household appliances in buildings have increased rapidly in the recent years. However, the surge withstanding capability of these household appliances has not been increased. Therefore, it is necessary to install surge protection device (SPD) to prevent serious damage of household electrical appliances caused by the in-rushing surges. In order to avoid the oscillation phenomenon, the effective protection distance of SPDs should be addressed before installing SPDs in the buildings. This paper discussed the influence of a group of common household electrical appliances connected in parallel on the effective protection distance of an SPD to a household appliance. The surges impinging on the household appliances connected to a distribution system are analyzed using electromagnetic transient analysis software. It is found that the SPD's protection distance increases when multiple household appliances are connected in parallel. The SPD's effective protection distance for one specific household appliance, which is determined from the case in which only this household appliance is used, is a conservative value; even if other household appliances are connected with this appliance, the SPD still provides an effective protection to this specific appliance.

Description: This index covers all technical items - papers, correspondence, reviews, etc. - that appeared in this periodical during the year, and items from previous years that were commented upon or corrected in this year. Departments and other items may also be covered if they have been judged to have archival value. The Author Index contains the primary entry for each item, listed under the first author's name. The primary entry includes the co-authors' names, the title of the paper or other item, and its location, specified by the publication abbreviation, year, month, and inclusive pagination. The Subject Index contains entries describing the item under all appropriate subject headings, plus the first author's name, the publication abbreviation, month, and year, and inclusive pages. Note that the item title is found only under the primary entry in the Author Index.

Description: We formulate and perform principal component analysis (PCA) of mechanically stirred fields, based on tuner sweep data collected across a frequency band at a single location of a sensor inside a reverberation chamber. Both covariance- and correlation-based PCA in undermoded and overmoded regime are performed and intercompared. The nonstationarity of the stir performance as a function of the angular position of the stirrer is demonstrated. It is shown that this nonuniformity can be quantified and exploited to select a set of optimal stir angles. The rotated principal components are found to be interpretable as energy stirred by specific angular sectors of the stirrer and are related to the correlation structure of the data. The analysis leads to the concept of eigenstirrings (stir modes), which form an orthonormal set of empirical basis functions for expanding stir data.

Description: This study relates to the delay of secondary electrostatic discharges (ESDs). The first motivation for this study is the fact that the delay value is a required input parameter for the simulation of the secondary ESD. The second motivation is that this delay is one limiting factor for the usage of spark gaps as protection devices. The objective is to determine the delay for different intended and unintended spark gap structures as this time delay will influence the peak current and rise time of the secondary ESD across these gaps. The intended application is ESD protection in consumer products, for that reason 0.5–3 mm gap distances and voltages up to 14 kV are considered at different humidity levels. Very long time lags are observed for clean sphere-to-sphere gaps requiring average field strengths >200 kV/cm to achieve a breakdown in a few nanoseconds in dry air. Humidity is shown to strongly reduce the time lag. However, if printed circuit board (PCB) spark gap geometries are considered the time lags are much smaller. Similar shorter lag times have been found in geometries that resemble more unintentional breakdown locations in a product.

Description: An electromagnetic (EM) cell is demonstrated to create the uniform electric field with 3-D polarization dynamic control for the EM compatibility/interference (EMC/EMI) testing. We utilize 3-D orthogonal slotline structures to build the walls of the EM cell and produce uniform electric field inside the cell by feeding the slotlines in phase and terminating them with matching loads. The uniform electric field is similar to a standing wave produced by the slotline modes propagating in opposite directions. Microwave switches are integrated into the slotlines so that we can choose the operating slotline dynamically and change its orientation in a 3-D manner by adjusting the ON/OFF state of the appropriate switches, which will consequently change orthogonally the polarization of the EM field generated by the operating slotline in 3-D. Both simulation and experiment show that a polarization controllable uniform field can be achieved in the center region of the EM cell from dc frequency to its first EM resonant frequency, enabling EMC/EMI testing more flexible without rotating the device under test.

Description: Provides a listing of current staff, committee members and society officers.

Description: Although the number of significant modes is intuitive, this concept has never been clearly defined, mainly because of the unbound number of modes involved in modal overlap. In the present paper, we show that, for a perfect stirring process, the effect of modal overlap can be modeled as an equivalent filtering formulation. By introducing the statistical-bandwidth concept, we show that the electromagnetic field statistics due to an infinite number of modes can be summarized by a finite number of significant modes. The case of the electric-energy density in an mode-stirred reverberation chamber has been considered and a new expression of its variability has been established. The good agreement found between the new expression and the experimental and simulation results support the several concepts introduced in this paper.

Description: The antenna factor (AF) above the ground plane changes with respect to the height and obtaining a height pattern of the AF with a sufficient resolution is time consuming. In this paper, a novel method is proposed to obtain an accurate AF at an arbitrary height by a single site insertion loss (SIL) measurement. A ratio of the $E$ -field strength at the location of the antenna under calibration (AUC) to the current amplitude at the transmitting antenna port is introduced. By using this ratio, the AF of the AUC at the height can be obtained by only one SIL measurement. Unlike the conventional method, the multiple SIL measurements are no longer necessary and the proposed method remarkably reduces the measurement time. By using the AFs properly calibrated by the proposed method, the effects of antenna characteristics are significantly reduced in the normalized site attenuation measurement.

Description: An original method allowing to define a particular frequency called “quasi-ideal reverberation chamber (RC) minimum frequency” is presented. This frequency corresponds to the frequency where an RC is considered as working in a “quasi-ideal regime.” According to the definition of an ideal RC, the method is based on the assessment 1) of the electromagnetic (EM) field distributions obtained in the working volume (in comparison with the distributions obtained in the ideal model defined by Hill [D. A. Hill, “Plane wave integral representation for fields in reverberation chambers,” IEEE Trans. Electromagn. Compat., vol. 40, no. 3, pp. 209--217, Aug. 1998.]) and 2) of the number of uncorrelated samples obtained over one mode stirrer revolution. The method is considered as helpful in order to optimize the functioning of an RC at low frequencies for broadband EM compatibility immunity and emission tests. Indeed, it is shown from experimental and numerical results that the insertion of an optimal loading in the chamber allows to decrease the frequency where the chamber works quasi-ideally. The influence of complexifying the mode stirrer geometry is also discussed.

Description: This study investigates the measurement of current on a wire located inside a cavity with an aperture as a function of excitation frequency with the use of a simple S parameter model. Validation is provided by comparing simulations and measurements. Using this approach, it will be possible to make an accurate prediction of the current distribution on the wire, and thereby to describe potential interference effects to equipment placed along the wire bundle at frequencies of interest.

Description: Near-field scanning is often used to solve electromagnetic compatibility (EMC) problems. Aside from the purpose of visualization of near fields, measured near-field data can be used to estimate radiated fields. One of many challenges associated with using near-field to far-field transform technique for EMC application is the handling of attached cables. The objective of this investigation is to evaluate different methods to add cable information to the near-field data for radiated-field estimation. The investigation is carried out using numerical experiments in EMCoS EMC Studio, which is a commercial software tool for EM simulation providing method-of-moments solver. Measurement results from a specially designed test structure are presented to validate the simulation results.

Description: An entire set of high-intensity radiated field transfer functions including the main types of contemporary test methods is presented. Consequently, the applied frequency range for this task expands over many decades, from the kilohertz range up to 40 GHz. A major aim is to demonstrate the application of numerical computer modeling for such a task. Results of measurements and various solvers are compared to each other. As the activity serves also for the validation of such applications, the scenario is investigated by the use of a fuselage model with limited complexity.

Description: A low-cost and transparent stainless steel fiber (SSF)/silicone resin composite was prepared by blending shortcut SSF with silicone resins. The SSF was homogeneously dispersed in resins at submicrometer scales and formed cross-linking structures. The visible light transmittance (VLT) and shielding effectiveness (SE) of composite in the frequency range of 300 MHz–1.5 GHz were investigated, and the result showed that the VLT was 70%, while the SE was 15–26 dB and the VLT was 67%, while the SE was 27–36 dB at 1.00 wt.% and 1.25 wt.% SSF concentrations, respectively. The result suggested that SSF/silicone resin composite may be useful for electromagnetic interface shielding application, especially when there is a visibility requirement. The shielding mechanism was investigated by quantitatively studying the absorbed and reflected energy to the total SE, and the result revealed that the dominant shielding mechanism of SSF/silicone resin composite was reflection loss.

Description: This paper presents measurements, simulations, and a theoretical basis to support the observation of spurious peaks on the output spectrum of a microwave phase-locked loop (PLL) exposed to a continuous wave electromagnetic interference (EMI). It is shown that high-power EMI combined to nonlinear characteristics of the PLL may induce subharmonic oscillation phenomena, which provoke the appearance of spurious peaks on the output spectrum. Measurements show that in addition to their dependence on the EMI power and frequency, these spurious peaks depend also on the natural frequency of the PLL and on its stability. Transient circuit simulations of the PLL allowing the prediction of these spurious peaks are presented. Finally, a theoretical explanation based on an analysis of a second-order PLL is given.

Description: Because of the importance of durability against electromagnetic interference in modern life, the shielding effectiveness of a rectangular cavity with apertures on different sides irradiated by the plane electromagnetic wave is modeled in this paper. In the modeling process, the incident angle and the polarization angle of the plane electromagnetic wave are introduced, and the scattering voltage produced on the outer aperture is taken as the radiation source. The aperture is taken as the asymmetrical coplanar stripline and the rectangular cavity is taken as a rectangular waveguide with one end completely open and another end completely closed. The shielding effectiveness of any point in the cavity is calculated using transmission line theory. Compared to other authors before, this method improves the completeness of the model and computation speed which supplies good reference for engineering practice.

Description: A procedure to synthesize a suitable biphasic composite material from the given Shielding effectiveness (SE) specifications is proposed herein. In particular, this paper presents an analytic approach for calculating parameters of a Debye-like equivalent homogeneous material, which meets the SE requirements in given frequency range. Establishing the relationship of the SE with the intrinsic material and morphological properties of a composite will make it possible to effectively find an equivalent homogeneous lossy Debye-like material model, starting from the given SE frequency characteristic. The Maxwell Garnett mixing rule is used to synthesize a composite made by aligned cylindrical inclusions. A few examples of how this procedure works are presented; validation by time domain numerical simulations is provided.

Description: This paper presents the effects of a continuous wave electromagnetic interference (EMI) on a discrete microwave phase-locked loop (PLL). Susceptibility of the voltage-controlled oscillator (VCO) is first studied as a standalone circuit before being integrated into the PLL. The effects observed on the VCO alone and when it is integrated into the PLL are analyzed as a function of the frequency and power of the interference signal. Most of the effects observed are due to intrinsic nonlinearities of the VCO. Some of them, like intermodulation and injection pulling can be predicted by the small-signal perturbation theory, while others such as a phase unlocking condition generated by strong EMI injection cannot. Finally, the consequence of using such an EMI affected PLL used as a local oscillator in a QPSK receiver, is examined. In all cases, the EMI is injected at the output of the VCO through inductive coupling.

Description: This paper presents a morphological and functional characterization of nanostructured thin films featuring high radio frequency shielding effectiveness and high optical transparency in the wavelength range 400–1500 nm. The film morphology is analyzed at the micro- and nanoscales by processing the images acquired by a scanning electron microscope. A software tool developed for this purpose analyzes the statistical distributions of the film surface grains. Fitting models and experimental evidences are presented in order to describe and predict the correlations between the film morphological and functional properties. The adopted approach and measurement methods are developed to model and optimize a particular transparent conducting oxide but can be easily extended to similar materials, deposition processes, and applications.

Description: This paper presents a new approach for modeling of electrically thin conductive shields in the finite-difference time-domain (FDTD) method. The method is based on representation of the relation between the fields at two faces of the shield as an impedance boundary network condition (INBC) in the frequency domain. The INBC includes frequency-dependent self and mutual impedances which are approximated by series of partial fractions in terms of real or complex conjugate pole-residue pairs. A discrete time-domain INBC at the shield is generated, which is then incorporated within the FDTD method. The primary advantages of the proposed approach are: 1) the convolution equations are not used in the formulation, 2) the approximation applied for discretizing the Maxwell equation has second-order accuracy in time and first-order of accuracy in space, and 3) the stability of the method is governed by the classical Courant Friedrichs Lewy stability condition. Numerical examples are presented to validate the new method and to demonstrate its efficiency and accuracy.

Description: The experimental characterization of the electromagnetic (EM) response of a set of inert improvised explosive devices (IEDs) is presented in this paper. The characterization is based on measurements of gain and input impedance of the firing circuits of inert IEDs in the range of 200 MHz to 2 GHz. First, a theoretical model to predict the average gain is developed. A comparison between the measurement results and theoretical predictions is presented. Then, the power delivered to a hot wire-based electro-explosive device connected to the inert IED is calculated for each measured case and it is statistically analyzed. The effects on the IED response of different characteristics of the coupling, such as the IED's elements, the incident field polarization, and the impedance mismatch, are also studied. In addition, the statistical performance of the induced power and current are determined and compared with the results of a numerical model based on Monte Carlo simulations. It is demonstrated that both approaches, a theoretical model based on an equivalent antenna and Monte Carlo simulations, can be used to describe the average EM response of the firing circuit of IEDs.

Description: In this paper, we investigate the influence of the excitation of improper radiating modes (leaky modes) in the propagation characteristics of coupled microstrip transmission lines. We calculate the crosstalk noise excited in the victim line and evaluate the impact of the presence of a metallic top cover due to the circuit packaging. The time domain propagation of pulses of different widths and rise times are computed in order to study the effect of the separation between the coupled strips on the crosstalk noise currents. We show that both even and odd leaky modes can be simultaneously excited on the covered microstrip structure at low frequencies. This can seriously compromise the signal integrity on the line because of the appearance of effects such as radiation, power loss, and interference, which are usually found in microstrip transmission lines at high frequencies. Our results are compared with those provided by a conventional analysis based on the quasi-TEM approximation and transmission line theory. For an open microstrip structure, we have found that the transmission line model accounts properly for the crosstalk current on the victim line. However, on covered coupled microstrip lines with a sufficiently low top-cover height, the crosstalk noise is higher than expected and cannot be accurately predicted by the transmission line model, even at frequencies where the cross section of the line is much smaller than the wavelength.

Description: We infer peak currents from radiation electric field peaks of 48 positive return strokes acquired in Gainesville, FL, USA, from 2007 to 2008. In doing so, we use the transmission line model, National Lightning Detection Network (NLDN) -reported distances, and assumed return-stroke speed. From a similar analysis of negative subsequent strokes, it appears that the implied return-stroke speed in the NLDN field-to-current conversion equation is 1.8 × 10 $^{8}$  m/s (the NLDN peak current estimation algorithm is calibrated for negative subsequent strokes). The NLDN uses the same field-to-current conversion procedure (and hence the same implied return-stroke speed) for positive return strokes. However, NLDN-reported peak currents for positive return strokes differ from peak currents predicted by the transmission line model with an assumed return-stroke speed of 1.8 × 10 $^{8}$  m/s. The discrepancy between regression equations for negative and positive return strokes suggests that the NLDN procedure to compensate for field propagation effects and find the average range-normalized signal strength (RNSS) works differently for these two groups of strokes. We find that the difference can be explained by the bias toward NLDN sensor reports from larger distances for positive strokes combined with the higher relative sensor gain (the ratio of sensor's peak current estimate to the NLDN-reported peak current) at larger distances.

Description: It is known that in applying the time-domain methods to study electromagnetic response of the system, the long time record required for generating accurate frequency domain results can be extrapolated from a relatively short time record by using Prony's method. In this paper, the electromagnetic shielding performances of two highly resonant enclosures with slot or aperture array are investigated by a combination of the finite-element time-domain (FETD) and extended Prony's method with a much smaller number of iterations. The procedure and details of using this combined method to investigate the shielding properties of highly resonant enclosures is demonstrated extensively. Moreover, some rules about selecting the parameters such as sampling position, sampling interval, sampling duration, and number of poles are proposed. As shown by comparison with the direct FETD generated results, the combined method achieves the same type of accuracy of frequency-domain delivered power with a FETD time record computed over a much shorter time duration.

Description: We present an analysis of the nearby electromagnetic fields generated by lightning discharges in the presence of a horizontally stratified, two-layer ground. To the best of our knowledge, this is the first time the effect of ground stratification on underground fields generated by lightning is analyzed. The analysis is performed by solving Maxwell's equations using the finite-difference time-domain technique. The return stroke channel is modeled using the modified transmission line model with exponential decay. The effect of the soil stratification on both above-ground fields and the fields penetrating into the ground is illustrated and discussed for two different cases characterized, respectively, by an upper layer more conductive than the lower level, and vice versa. The analysis was carried out for close distances (10 m–100 m from the channel). It is shown that, for these distances, the ground stratification does not significantly affect the electromagnetic fields above the ground. The above-ground vertical electric field and the azimuthal component of the magnetic field can be calculated assuming the ground as a perfectly conducting plane. The above-ground horizontal electric field is essentially determined by the characteristics of the conductive layer and it can be computed considering a homogeneous ground characterized by the conductive layer conductivity as long as the depth of the upper layer remains below 10 m or so. In general, the fields penetrating into the ground are markedly affected by the soil stratification. The electromagnetic field components inside the stratified soil are generally characterized by faster rise times compared to those of the field components in the case of a homogeneous ground with the upper layer characteristics. The peak value of the horizontal electric field is found to be very sensitive to the ground stratification. The horizontal electric field peak decreases considerably in the presence of a lower l- yer of higher conductivity. On the other hand, the presence of a lower layer with lower conductivity results in an increase of the peak value of the underground horizontal electric field.

Description: The planar electromagnetic interference (EMI) filter has good application in aviation for its easy magnetic integration, small parasitic parameter, and strong anti-EMI ability. Based on the annular structure, the common-mode (CM) and difference-mode (DM) modules are proposed. The former is formed by “capacitance and inductance” (LC unit), while the latter is formed by an independent DM capacitor and the leakage inductance of the LC units. The extraction of the unit-length electromagnetic parameters is the foundation of analyzing the characteristics of the modules and further the whole EMI filter. The axisymmetric electrostatic field model of LC unit is established to extract the turn-to-turn partial capacitances. Considering the skin effect, proximity effect, and core loss, the model of harmonic magnetic field of LC unit is also established to extract the inductances and resistances. To obtain the leakage inductance that serves as the DM inductance, the model of harmonic magnetic field with a leakage layer between LC units is studied. The DM capacitance can be calculated directly using the approximate expression of a parallel plate. Finally, the impedances of the LC units can be drawn out with the obtained distributed parameters under the appreciate boundary conditions, and they are compared with the measured results. The results verify the accuracy of the extracted parameters and the validity of the proposed extraction method.

Description: A multiresolution time-domain (MRTD) method is proposed for cloud-to-ground lightning electromagnetic pulse (LEMP) calculation. Scaling function of Daubechies wavelet is chosen for fields expansion, and iterative formulas of MRTD method are derivated in 2-D cylindrical coordinates. First, three double-exponential lightning channel-base current with different rise times have been used for evaluating performance of the finite-difference time-domain (FDTD) method. And then, LEMP of different distances of the lightning channel were calculated with the MRTD method. We examined the MRTD method by comparing the results obtained with the FDTD method. Numerical simulation results show that the MRTD method and FDTD method are consistent with each other for first return stroke, even with a larger grid division. However, for subsequent return stroke, oscillations will be observed in the late response of the waveforms calculated by the FDTD method. Comparing with the FDTD method, the MRTD method suffers less oscillations with the same grid division, and can significantly save both computational memory and CPU time with large gird mesh, as well as good numerical dispersion property.

Description: The solution of mixed electromagnetic/circuit problems is important for the electromagnetic compatibility/signal integrity/power integrity system designs. The ever-increasing frequency content of signals and decrease of geometrical features requires the 3-D electromagnetic methods, such as the partial element equivalent circuit (PEEC) method, to be used for the analysis and design of high-speed circuits. Very large systems of equations are often produced and their efficient solution can be extremely challenging. In this paper, we propose a new frequency-domain PEEC solver which is based on the adaptive cross approximation and singular value decomposition. Taking advantage of the rank deficiency of the dense partial inductance and coefficient of potential matrices, a multiscale block decomposition is adopted to explicitly compute the inverse of the admittance matrix of the PEEC circuit. The proposed approach provides both speedup and memory storage saving, while preserving the accuracy. The efficiency of the proposed method is demonstrated through its application to the PEEC modeling of typical interconnect problems.

Description: This paper proposes approximate formulas to estimate voltages on a horizontal grounding conductor. The formulas are derived in the time domain using Bewley's lattice diagram method based on transmission and reflection coefficients. The expression of the approximate formulas is simple, and the formulas are useful for engineers to carry out grounding system design for lightning protection. This paper concerns a voltage source with step waveform. A formula for an arbitrary voltage waveform can be calculated by using Duhamel's integral. Surge characteristics of voltages and an effective length of a grounding conductor are discussed using the proposed formulas. It is easy to understand experimental and simulation results of a grounding system using the approximate formulas.

Description: The time-domain counterpart of the Okoshi’s contour integral method is formulated with the aid of the reciprocity theorem of the time-convolution type. A numerical procedure for solving the time-domain reciprocity relation is proposed and validated using an analytical solution based on the eigenfunction expansion and the finite-integration technique. For the former, the time-domain counterpart of the classical double-summation formula for a rectangular power-ground structure is found and evaluated.

Description: The electric far-field radiated from a printed circuit board (PCB)–chassis system is characterized using a cavity resonator model employing the far field calculated using an equivalent magnetic current loop. The inductive network method with measured current flowing through screws as a stimulus is used to calculate the frequency spectra of the electric field strength along the edge of the PCB with various locations of screws that connect the PCB ground to the chassis. Electric far fields from the equivalent magnetic current loop were derived using correction coefficients that incorporate the asymmetric dimensions of a parallel pair of PCB planes and the chassis. The calculation results reveal that the horizontal far field exceeds the vertical far field due to the asymmetric size coefficients and exhibit good agreement with the measurement results.

Description: In this paper, we analyze the influence of the horizontally stratified conducting ground on the lightning-induced overvoltage on the overhead line by using the 2-D Finite-Difference Time-Domain method and the Agrawal coupling model. In order to clearly understand the propagation characteristics of the induced voltage waves along the line, we split the induced overvoltage into the scattered induced wave $(U_{s})$ and the incident induced wave $(U_{i})$ , and the latter is further decomposed into two subcomponents. When the conductivity of the first layer $({sigma}_{1}$ = 0.001 S/m, ${varepsilon}_{r}$ $_{1}$ = 10) is less than that of the second layer ( ${sigma}_{2}$ = 0.1 S/m, ${varepsilon}_{r}$ $_{2}$  = 10), the lightning-induced overvoltage increases obviously with the increase of the depth of the first layer due to the increase of the total effective impedance, and we should consider the influence of the stratified ground if the depth of the first layer is more than 2 m. However, the lightning-induced overvoltage decreases sharply with the increase of first layer depth with much higher conductivity ( ${sigma}_{1}$ = 0.1 S/m, ${varepsilon}_{r}$ $_{1}$ = 10; ${sigma}_{2}$ = 0.001 S/m, ${varepsilon}_{r2}$ = 10). Also, we find that when the lower different conductivities between the two layers (i.e., 0.01 and 0.001 S/m) are assumed, the characteristics of the induced voltages are similar to that from the higher difference.

Description: This letter investigates the use of multiple coils for the powering of and the data communication to brain implants. It studies the limits imposed by these coils in terms of biosafety and interference in the communication channels caused by neighboring and misaligned coils. Simulations using the CST Studio voxel head model are used to assess the associated health risks as well as the resilience of the proposed data communication scheme.

Description: We analyzed how the position of the stirrer influences the reverberation chamber (RC) performance. We simulated a RC moving the rotation axis of the stirrer from a corner to the center. Simulation is carried out by a finite-difference time-domain code optimized for high-performance computers. Results show that the stirrer rotation center position weakly affects the most used statistical parameters.

Description: An optimized conformal finite-difference time-domain (FDTD) (2, 4) method is proposed for calculating reflected, diffracted, and total fields of two- and three-dimensional (2- and 3-D) perfectly conducting (PEC) wedges with an electromagnetic pulse (EMP) incidence, where one low-cost coefficient-modification (CM) technique is implemented for effectively reducing its numerical dispersion error. For the 2-D geometries, both reflected and diffracted fields are extracted from the whole calculation domain of FDTD (2, 4), and excellent agreement is achieved between the calculated diffraction coefficient and the analytical one obtained by high frequency approximation method of UTD. While for the 3-D wedges, even with the coarse FDTD cells adopted, such an optimized method still possesses the capability for getting more accurate diffracted fields in comparison with the conventional FDTD.

Description: The development of large-scale photovoltaic (PV) plants in rural areas is constantly increasing. However, the knowledge of performing and installing lightning and surge protection in large-scale PV plants is still premature. The main objective of this paper is to provide a method for assessing the external lightning protection and earthing designs that may be installed in large-scale solar applications. Consequently, the method and models presented in this paper may assist engineers to perform a comparison between the use of isolated and nonisolated lightning protection systems, and second to select suitable surge protection equipment.

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Description: The assessment of the shielding effectiveness of enclosures under transient conditions calls for an accurate analysis of fundamental aspects. Stemming from a correct understanding of the coupling mechanism and from a victim point of view, new shielding parameters are proposed as figures of merit to designate the actual effectiveness of an electromagnetic enclosure. Their suitability is tested in different configurations excited by typical transient electromagnetic threats.

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Description: A simple and fast coating method of honeycomb cores for microwave absorption has been described. The honeycomb cores with two different thicknesses (5 and 20 mm) coated with thermoplastic resin filled with carbon powder as lossy filler in 5, 10, 15, and 20 wt% have been tested for microwave absorption in 2 – 18-GHz frequency range. The 5-mm-thick honeycomb has shown absorption bandwidth of 14 GHz for maximum absorption of −6 dB (75%) with 15 wt%. filler content. However, the percentage of the filler was decreased to 10 wt% in 20-mm-thick honeycomb absorber for maximum absorption over a wide frequency range. The honeycomb sample with 10 wt% filler has bandwidth of 18 GHz for −7 dB (80%) reflection loss. The reflection loss measurements of coated honeycomb cores have also shown that use of E-glass fiber/epoxy composite can enhance the performance of the honeycomb absorber. The combination of a microwave absorbing nanocomposite and the coated honeycombs has been resulted in inferior absorption properties in 2 – 18-GHz frequency range.

Description: A method of determining electromagnetic interference shielding effectiveness of various cases has been developed using a modeling technique where radar cross section (RCS) is used in the calculation of shielding effectiveness and a planar wave is utilized to model mode stirring in the reverberation chamber. In addition, a new shielding effectiveness equation is derived in terms of RCS. Three different test cases based on the small form-factor pluggable family are measured and compared to the simulation results based on the derived shielding effectiveness equation. The measurement and simulation results are plotted and compared to validate the proposed modeling methodology. It was found that results from the measurement and simulation are in good agreement and the simulation method is validated.

Description: The positioning of electromagnetic (EM) sources on the complex plane, though a mathematical construct, is often applied in solving EM problems with directive confined (collimated) propagation characteristics. Equivalent dipole modeling, which finds its application in characterizing various current sources can be computationally expensive for large structures. Here, the complex localization of equivalent source points combined with the particle swarm optimization is used to improve the performance of the equivalent dipole modeling.

Description: In this paper, a component-level electromagnetic interference (EMI) evaluation method for multifunctional mobile devices is suggested. The proposed method is based on the extraction of the transfer function between the component-level and the system-level radiated emissions. To demonstrate the practical correlation between the near-field emission from components or modules and far-field radiation from systems, measurement-based transfer functions are extracted by testing various mobile phones integrating camera modules as a target component. A specification for the component-level EMI evaluation is developed with a statistical transfer function and the system-level EMI regulation of CISPR. The proposed evaluation method is experimentally verified using 86 real mobile phones with a good correlation between the component-level and the system-level evaluation results.

Description: Study on electrostatic discharge (ESD) impact on the GaAs HBT power amplifier (PA) in DCS/GSM dual band handsets is performed in this paper, which has been regarded as its main reliability issue accounting for most failures of radio frequency integrated circuits. In order to suppress the positive ESD impact on the PA in an effective but very economic way, a set of forward ESD diodes at its input port is replaced by the PN junction of GaAs HBT transistor in its first-stage. Alternatively, to introduce a set of thin film resistors (TFRs) at the front of a HBT transistor is necessary for improving the S $_{11}$ -parameter and stability of PA; however, their electrothermal breakdown possibilities do exist. Therefore, both performance degradation and breakdown events of several PA dies are measured for different ESD voltages described by the human body model, with different TFRs chosen for both DCS and GSM bands, respectively. Their transient temperature responses are also captured and compared for different ESD waveforms, which are predicted using the in-house developed algorithm based on the hybrid time-domain finite-element method.

Description: This paper presents the calculation of electric and magnetic fields produced by lightning striking over different configurations of nonflat lossy ground. The computation is performed using finite-difference time domain (FDTD) methods in two-dimensional (2-D) with cylindrical coordinate systems and 3-D with Cartesian coordinates. The FDTD method is validated with several previous approximations for lightning electric field computation, such as Uman equations and simulation of lightning striking on the top of a tower. In this study, it is found that lightning striking on the top of a cone-shaped mountain may produce several variations on an electromagnetic field. An enhancement of the perpendicular and parallel to ground electric field components was observed for a cone-shaped configuration only. For configurations that include flat planes, wave reflections due to the transition between the cone-shaped and flat plane were observed.

Description: Based on the two-dimensional finite-difference time-domain (2-D FDTD) method, we have validated the time-domain method presented by Barbosa (B-P formula) for calculating the lightning-radiated horizontal electric field at the earth surface within distances from 30 to 1000 m from the lightning channel, considering the horizontally stratified earth. The results show that, except for distances in the vicinity of the lightning channel (e.g., 30 m), the B-P approximate formula can approximately predict the field peak value from 50 to 1000 m with a satisfactory accuracy within errors of 10% and its accuracy for subsequent return strokes seems to be more or less the same as that for first return strokes. The rise-time part of the field wave predicted by the B-P approximate formula is similar to that predicted by the 2-D FDTD, however, the tail of the wave predicted by the B-P approximation may be shorter than that by the 2-D FDTD (e.g., 30 and 50 m).

Description: The impact of the frequency dependence of soil resistivity and permittivity on lightning overvoltages induced on overhead lines over lossy ground is investigated. The Visacro–Alipio expressions were implemented on the hybrid electromagnetic model to take this effect into account. Systematic simulations were performed considering representative current waveforms of first and subsequent strokes and different stroke locations near the simulated overhead line. In general, the results indicated that this effect is responsible for a reduction of the induced overvoltage. This reduction increases with increasing soil resistivity and becomes relevant for soil resistivity above 1000 Ω·m.

Description: We use a finite element method (FEM) to evaluate the effect of a horizontally stratified two-layer ground on underground lightning electromagnetic fields and their induced currents on the shield of buried cables. It is shown that the azimuthal component of the magnetic field in the upper soil layer is affected by the soil stratification only when this layer is more conductive than the lower soil layer. On the other hand, inside the lower soil layer, this component is always affected by the soil stratification. The vertical electric field in the upper soil layer is mainly determined by the conductivity of the same layer in particular at close observation points. However, this component inside a more conductive lower soil layer is identical to that corresponding to a homogeneous soil with the same property of the lower soil layer. The horizontal electric field inside a stratified ground always takes values in between the electric fields corresponding to one-layer homogenous grounds. We also present a comparison with available experimental data on induced currents of a shielded buried cable and show that, in agreement with recent studies, taking the soil stratification into account allows to improve the late-time response of the induced currents. We also show that the horizontal stratification of soil may result, in some cases, in an enhancement of the induced currents with respect to the case of a homogeneous ground characterized by the electrical properties of either of the two layers.

Description: We use a full-wave finite-element-based solution of Maxwell's equations for the evaluation of lightning electromagnetic fields inside a vertically stratified, two-layer ground (ocean–land mixed propagation path) and their induced currents on the shield of buried cables. For “normal” incidence (with respect to the ocean–land interface), it is shown that the vertical electric field is the component most affected by the ocean–land mixed path when the observation point is close to the ocean–land interface (i.e., 5 m or so). For “oblique” incidence, however, depending on the angle of incidence and the distance between the observation point and the ocean, all the field components are reduced by the ocean–land interface. For the calculation of induced currents, and for the case of a parallel layout (cable laying in parallel to the ocean–land interface); 1) for a strike to the land, when the cable is buried in the soil and the distance to the ocean is greater than about 100 m, the effect of the ocean is negligible. 2) For a strike to the ocean, the induced current magnitudes are appreciable only when the cable is entirely within the land. For the case of a perpendicular layout (cable perpendicular to the ocean–land interface); 1) for a strike to the ocean, when the cable is totally buried in the ocean, the effect of ocean–land mixed propagation is negligible. However, when the cable extends into the land through one end, the induced currents increase at both ends with increasing length of underland portion. 2) For a strike to the land, when the cable is located entirely inside the land, the effect of ocean–land mixed path on the induced currents at both ends is negligible. However, as the cable extends into the ocean, a remarkable enhancement in the induced currents is observed for the termination located inside the land. This enhancement can be a- high as a factor of 2 with respect to the case of a cable in homogeneous soil characterized by the properties of the land.

Description: A new technique for the reluctance method applied to the partial element equivalent circuit method for the time-domain analysis is presented which is well suited to be combined with acceleration techniques. In particular, taking advantage of the rank deficiency of the magnetic and electric field couplings, a new technique for the sparsification of reluctance and capacitance matrices is adopted. Furthermore, the multiscale block decomposition technique has been applied to fast fill these matrices. Finally, the sparse multifrontal LU factorization has been adopted to efficiently compute the global solution. Numerical results demonstrate the validity of the proposed approach in terms of speedup and accuracy.

Description: A novel common-mode (CM) EMI active filter for dc-fed motor drives is proposed. The active filter performs both the compensation of the CM voltage at the motor input and the mitigation of the leakage high-frequency CM currents, thus increasing the drive reliability and the vehicle electromagnetic compatibility (EMC). The filter scheme is based on a voltage feedback action and also includes a feed-forward action by exploiting a suitably estimated CM current. An optimized design of the CM voltage detection/injection systems is implemented. Moreover, the active filter is supplied by a smaller voltage than the dc link value; this permits a more performing amplifier to be used. The active filter behavior is analyzed theoretically and its performance is assessed by experiments. The realized prototype shows a good efficiency and compactness.

Description: Transient performance of grounding systems is simulated using the finite-difference time-domain (FDTD) method for solving Maxwell's equations. The derivation of the transient current is first adjusted to obtain accurate impedance. Then, the FDTD calculation model is optimized to predict the grounding system impedance accurately without resulting in huge computational resources. From evaluation, the direction parallel to the connecting line is supposed to integrate the transient voltage. The transient voltage should be integrated 20 m in length and the reference electrode to be 30 m from the grounding system, and these lengths should be further enlarged for a large dimension grounding system. The transient impedance of the five lightning current components is very close to each other except the multiple burst, and the current should be injected close to the ground.

Description: The rectangular power-ground structure is thoroughly analyzed in time domain. The time-dependent electric-field distribution within the power-ground structure is expanded in ray-like constituents that propagate via the reflections against circuit’s periphery. Their relation to the classical eigenfunction expansion is demonstrated. It is shown that the ray-type expansion is always exact in any finite time window of observation and can be readily generalized to account for dissipation and relaxation mechanisms. Obtained results concerning a dispersive dielectric described through finite conductivity and Debije relaxation models are discussed and validated on a number of illustrative examples.

Description: This letter presents a novel signal reconstruction technique using the associated-Hermite (AH) orthogonal functions. By adjusting the scaling factor and the time shift, a serious of AH functions with limited order can be used to approximate typical electromagnetic pulse signal. Because AH functions are also eigenfunctions of the Fourier transform operator, the transfer function of an unknown system can be described by the AH expansion coefficient of the input and output waveforms. This transfer function can be further used to reconstruct the measurement signal deformed by the nonideal features of the system. Compared to traditional FFT method, the transfer function obtained by AH expansion is a parametric model with higher stability. This method is applied to reconstruct the output of a coaxial high-voltage pulse probe, and the reconstructed waveforms are compared to the results obtained by FFT method and the system identification method.

Description: The partial element equivalent circuit (PEEC) method has been widely used in different industrial and scientific fields for electromagnetic analysis. PEEC-based solvers have been optimized and accelerated in order to be able to solve larger and more complex problems that arise in industry. In power electronic system simulations, PEEC models are often simplified by neglecting electric field couplings and using quasi-static model. The simplified system can be further accelerated using reluctance technique and then sparsified up to high levels without degrading the accuracy of the solution. In previous work, the sparse system was solved using sparse direct solution, while in this study, an iterative approach is employed which resulted in lower time complexity of the solution. However, since matrices achieved from PEEC equations are severely ill-conditioned, regularization techniques need to be applied to avoid numerical instabilities. The regularization is done mathematically and can be interpreted as adding a frequency-dependent pseudocapacitor to each node in the PEEC model. Because the pseudocapacitors are frequency dependent, hence frequencies close to dc are not covered in this study and have left as future work. The new sparse and regularized system can then be solved using a Schur complement technique together with iterative solvers with a novel preconditioning approach.

Description: The paper proposes an efficient hybrid technique based on the finite-difference frequency-domain (FDFD) method and the method of moments (MoM) to study the susceptibility of a terminated microstrip transmission line (MTL) inside a perforated rectangular enclosure. The complex geometry of the inside cavity region is treated by an efficient FDFD method, whereas the unbounded outside region of the enclosure is analyzed by a MoM solution. To account for the relatively thin microstrip dielectric, a nonuniform meshing scheme is adopted for the FDFD method. Also, linear lumped elements connected to the MTL are modeled by changing the related node information in the mesh according to the element type and direction. The validity of the proposed technique is confirmed by comparing our simulation results with those obtained using a commercial finite integration code and measurement results.

Description: In this paper, a procedure for computing transient electromagnetic fields with the constrained interpolation profile (CIP) method in the two-dimensional (2-D) cylindrical coordinate system has been derived. Then, it has been applied to analyzing electromagnetic pulses produced by a current wave propagating upward along a vertical lightning return-stroke channel. CIP-computed waveforms agree well with corresponding waveforms computed using analytical expression of Uman et al . or the finite-difference time-domain method.

Description: Electromagnetic computation methods (ECMs) have been widely used in analyzing lightning electromagnetic pulses (LEMPs) and lightning-caused surges in various systems. One of the advantages of ECMs, in comparison with circuit simulation methods, is that they allow a self-consistent full-wave solution for both the transient current distribution in a 3-D conductor system and resultant electromagnetic fields, although they are computationally expensive. Among ECMs, the finite-difference time-domain (FDTD) method for solving Maxwell's equations has been most frequently used in LEMP and surge simulations. In this paper, we review applications of the FDTD method to LEMP and surge simulations, including 1) lightning electromagnetic fields at close and far distances, 2) lightning surges on overhead power transmission line conductors and towers, 3) lightning surges on overhead distribution and telecommunication lines, 4) lightning electromagnetic environment in power substations, 5) lightning surges in wind-turbine-generator towers, 6) lightning surges in photovoltaic (PV) arrays, 7) lightning electromagnetic environment in electric vehicles (EVs), 8) lightning electromagnetic environment in airborne vehicles, 9) lightning surges and electromagnetic environment in buildings, and 10) surges on grounding electrodes.

Description: The effectiveness of the random coupling model (RCM) in predicting electromagnetic wave coupling to targeted electronic components within a complex enclosure is examined. In the short-wavelength limit with respect to the characteristic length of the enclosure, electromagnetic wave propagation within a large enclosure is sensitive to small changes to the interior, or to the boundaries of the enclosure. Such changes can reduce or invalidate the applicability of deterministic predictions of the electromagnetic fields at radiofrequencies (RF) in large enclosures. Under such circumstances, a statistical approach is needed to provide a better understanding of RF coupling to components within large enclosures. In this paper, we experimentally demonstrate the applicability of a statistical technique, the RCM, to estimate the probabilistic magnitudes of RF fields on electrically large components (i.e., long cables, etc.) that are partially shielded within a complex, 3-D enclosure.

Description: In the electromagnetic compatibility (EMC) behavior of power electronic converters, magnetic parasitic couplings between components are one of the main causes of dysfunctions or bad filtering (e.g., in EMC filter). These couplings could be as conducted or near-field interferences. In order to handle interaction problems, a complete knowledge of these magnetic couplings is then necessary. Our study is focused on near magnetic field's interferences. Indeed, the characterization of electromagnetic field in power electronics is still in active research. This paper details a predictive method that calculates accurately and efficiently the near magnetic field coupling between two sources. By using the near-field multipolar expansion in spherical harmonics of electromagnetic sources, the close magnetic coupling between two sources is determined from their equivalent model. It is shown that the increase in degree up to the fourth provides a more precise representation of the elements and thus a better accuracy of the near-field coupling prediction. Also, theoretical and experimental developments will be presented. The coupling between two complex sources will be considered to validate the predictive method.

Description: In this paper, we present an incremental multilevel matrix filling and sparsification scheme for the method of moment (MoM) solution of the electric field integral equation at low and very low frequencies. The proposed scheme allows a strong reduction of the memory requirements without a loss in accuracy. Numerical results show the method performance in terms of memory requirements, CPU time and accuracy with respect to the standard MoM, the multilevel fast multipole algorithm, and the adaptive cross approximation.

Description: A novel boundary element method approach with the rectangular cavity Green's function is presented and utilized to model reverberation chambers. Different from all other approaches that employ rectangular cavity Green's functions, the computationally expensive part of the matrix-vector product is evaluated in the spectral domain. A drastic acceleration is achieved even though the algorithm operates with excellent accuracy. The approach is validated and compared against the boundary element method with free-space Green's function. Examples demonstrate the usability of the proposed approach.

Description: Plane wave shielding effectiveness is frequently expressed as the sum of three terms called absorption loss, reflection loss, and a multiple reflections term. This well-known decomposition was introduced by Schelkunoff and provides an intuitive way of relating material properties to the overall shielding effectiveness. This letter derives equations relating the Schelkunoff decomposition terms to the reflectance/absorptance of good conductors. Additionally, the relationship between the Schelkunoff decomposition and another decomposition, called the mismatch decomposition in this letter, is analyzed. The mismatch decomposition consists of two loss terms closely related to reflectance/absorptance that are readily obtained from measurements.

Description: Near-field probes with high sensitivity facilitate the identification of the root causes of intrasystem radio frequency interference issues, where weak noise desensitizes the receiver. In the study presented in this paper, a high-sensitivity resonant electric field probe was designed, consisting of an LC resonator loaded by quarter-wave transformers for optimal power transfer at the resonant frequency. Based on the equivalent circuit model, analytical derivations and numerical simulations were performed to illustrate the design methodology. The simulation results agreed well with the measured values. At the resonant frequency of 1.577 GHz, the measured $vert S_{21}vert$ from a matched trace to the resonant probe was approximately 6.6 dB higher than that of an equivalently sized broadband probe.

Description: This paper is focused on the analysis of the shielding properties of reinforced concrete under impinging high-altitude electromagnetic pulse. The reinforced concrete provides frequency-dependent shielding effectiveness mainly due to the embedded metallic grid rebars. For characterization of the concrete, three different configurations, i.e., concrete, rebar, and combined reinforced concrete, are analyzed in detail. In addition, the electromagnetic properties of concrete are quantitatively analyzed by its frequency dependence, moisture content, and material mixture ratio. According to the obtained results, as the rebar spacing decreases and the rebar diameter is increased, the transmission coefficient is gradually decreased. In particular, for reinforced concrete with built-in double layered rebar, it is possible to obtain a transmission coefficient approximately 40 dB less than that achieved by single rebar.

Description: A burst stimulus of data is a common activity in circuits and systems. The supply noise voltage waveform induced by a burst train of integrated circuit (IC) switching currents is rigorously derived for a power distribution network (PDN) with power traces, commonly used in handheld devices. Closed-form expressions are proposed to quickly estimate the amount of voltage drop and overshoot and to develop more complete PDN design methodology as improved target impedances. The proposed PDN noise expressions are also validated with SPICE simulation and measurements using a fabricated IC and PCB.

Description: Failure examination is carried out by a scanning electron microscope on gallium arsenide (GaAs) high electron mobility transistor (HEMT) monolithic microwave integrated circuit damaged with microwave pulses. The examination results show that there are four types of defects in ten damaged chips. Among the previous types, one type of defect occurred in most damaged chips was examined, namely the planar spiral inductor between the output terminal of the last-stage HEMT and dc power supply is burned out. Specific to this type of defect, combining with the conductor loss theory and heat formula, the mechanism of heating and melting exerted on the planar spiral inductor of the chip under the action of microwave pulses is analyzed in this paper. The input power required for reaching Au and Cu microstrip melting point is computed.

Description: A statistical method for predicting the vulnerability of a target, i.e., critical equipment, located inside a building subject to a radiated Intentional Electromagnetic Interference (IEMI) source outside a building, has been devised. Combining probability density functions of small- and large-scale fluctuations of the electric field strength results in a Suzuki distributed electric field strength impinging at the equipment. Specifying the susceptibility level or the critical electric field strength of the target, the vulnerability of a target is evaluated as a function of the distance between source and target, taking into account losses from in and outside the building. Vulnerability isocontours defined as lines of constant probability of exceeding the susceptibility level are presented for a generic, continuous wave power source in a scenario emulating a dense urban microcell propagation environment. A comparison of the vulnerabilities predicted based on the Suzuki and the Lognormal distributions are also been provided for the same scenario. The proposed method provides estimates of critical distances of radiated IEMI attacks and may have use when deciding on the perimeter defense of a facility.

Description: Recently, an experiment-based traveling-wave technique to separate conductor loss from dielectric loss on printed circuit board (PCB) striplines, called the differential extrapolation roughness measurement (DERM), has been proposed. The further development of this procedure is presented in this paper. The new procedure is applied to both loss constant and phase constant, as opposed to the previous procedure, which is applied to only loss constant. A new roughness parameter QR to quantify conductor surface roughness has been proposed, and it is used in the improved procedure. This allows for more accurate extraction of dielectric constant and loss tangent over a wide frequency range. In this paper, the three sets of test vehicles are studied. Each set has three different types of copper surface roughness profiles; two of these sets are known to have the same dielectric, which is used for the validation of the proposed extraction procedure. The new corrected extracted dielectric parameters as functions of frequency for these sets of test vehicles are compared with those obtained using the previous DERM technique.

Description: This paper presents an exhaustive analysis of the frequency-dependent series resistance and inductance associated with the distributed model of on-chip interconnects including a ground shield to reduce substrate losses. This analysis identifies the regions where the resistance and inductance curves present different trending due to variations in the current distribution. Furthermore, the apparent discrepancy of experimental curves with the well-known square-root-of-frequency models for the resistance and inductance considering the skin-effect is explained. Measurement results up to 40 GHz show that models involving terms proportional to the square root of frequency are valid provided that the section of the interconnect where the current is flowing is appropriately represented.

Description: A SPICE-based model of a microcontroller was developed to investigate its immunity to electrical fast transients (EFTs). The model includes representations of the on-die power delivery network, the ESD protection clamps, and the I/O driver circuits. Several measurement approaches were developed to characterize the linear and nonlinear components within the model. EFTs were injected into pins of the microcontroller to verify the accuracy of the proposed model. General purpose I/O were tested in several configurations (i.e., pull-up-enabled input, logical-high output, and logical-low output). The model was able to predict the voltage waveform and maximum voltage at each pin within 5∼6% of the measured values. A parasitic bipolar junction transistor associated with the output driver was found to have a critical impact on the noise coupled to the power bus. The simplicity and accuracy of this model shows its promise for understanding and predicting immunity issues in integrated circuits.