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Prediction of the voltage distribution within the winding due to pulsewidth modulated voltage impinging at the machine terminals is prevalent in the literature. For this purpose, the state-of-art work employs a high-frequency model of the stator winding but fails to represent the mutual inductive and resistive couplings between the turns and the coil. Herein, this article proposes a multiconductor transmission line model for representing the high-frequency behavior of the stator winding. A distinctive feature of the proposed model is that it incorporates the mutual inductive and resistive coupling between the turns and the coils using a current-dependent voltage source with due account of frequency-dependent parameters in the form of a ladder network. It enables the modeling of the mutual coupling of both single and multilayer winding in the time domain without the explicit use of modal transformation, convolution integral, or inverse Fourier transform. The close agreement between the simulation and the experimental results validates the proposed model of an automotive-grade 60-kW permanent magnet synchronous machine adapted in the Toyota Prius vehicle. In addition, a more intuitive analytical model is proposed to explain the voltage distribution and to characterize the peak voltage stress within the winding. The analytical model can be used to predict voltage stress as an alternative to the high-frequency model. [ABSTRACT FROM AUTHOR]

A ubiquitous tool in science, physics, and engineering at large, the transfer matrix method (TMM) is particularly suited to deal with complex nonuniform systems (NUS). In the field of electrical engineering, the method is employed in a variety of disciplines that span the electromagnetic spectrum, from power frequencies through RF, millimeter-waves, and terahertz. In this work, three nested goals are pursued. The first is to present a general comprehensive review of the transfer matrix method utilizing two distinct languages: the state space (via the matricant) and the modal analysis (via matrix diagonalization). The second goal, focused on electrical engineering issues, is the application of TMM to the interdisciplinary theme of nonuniform multiconductor transmission lines (MTL) -a good example of a complex reciprocal multiport system. The third goal is to offer the reader novel research results in the context of MTL analysis. Making use of a simple microwave stripline-coupler structure new theoretical results are presented showing that, in some cases, load impedance matching of nonuniform MTLs, using only passive components, may not be physically possible (negative resistors being required), even if the global NUS is longitudinally and transversally symmetric, with or without losses.

In the development of alternative test methods for pre-compliance radiated-susceptibility (RS) investigations, it is proven that a special test setup, involving an additional wire placed in proximity of the cable under test and fed by two radio-frequency generators, can reproduce through crosstalk (XT) the same terminal voltages/currents induced in the standard RS test setup, on condition that those generators are properly controlled in magnitude and phase. Such a test setup does not require expensive facilities like anechoic chambers and powerful amplifiers to feed antennas, therefore it represents a fast and cheap alternative to get feedback on radiated immunity in the early-design stage, before the formal RS assessment carried out according to standards. While in past literature works the equivalence between XT and RS was demonstrated for some simple cables like a single bare wire or a differential pair, this paper presents a new XT-based test setup suitable for the practically relevant case of a complex bundle of dielectric-covered wires. To this aim, two different formulations of feeding conditions are proposed, one more rigorous, based on multiconductor-transmission-line modeling, and one approximate, based on bundle-reduction techniques. The performance of both the equivalence schemes is assessed and discussed in the frequency range between 1 MHz and 1 GHz.

This paper presents an effective solution for the crosstalk prediction of handmade cable bundles. The outer- and inner-layer topology of the cross section are analyzed respectively, combined with the actual physical model of the cable bundles. The cascading method is used to deal with the relationship between the structure of cable bundles and the distributed per unit length (p.u.l.) parameter matrices. The random exchange of the wires in the cable bundles is equivalent to the row--column transformation of the p.u.l. parameter matrix, and the values of the p.u.l. parameter matrix after the transformation are modified by equal interval rotation degree. Then, the unconditionally stable finite difference time domain (FDTD) method is used to solve the crosstalk. The verification analysis shows that the change of the element value of the p.u.l. parameter matrix caused by the rotation of the cross-section relative to the ground cannot be ignored. The accuracy of the proposed method is evaluated through comparison to the probability method for a seven-core handmade cable bundles, especially in the high frequency. [ABSTRACT FROM AUTHOR]

This study analyzes the uncertainties of the radiated susceptibility in multiconductor transmission lines (MTLs), and introduces an adaptive sparse polynomial chaos expansion combining hyperbolic truncation scheme with orthogonal matching pursuit method (AS-PCE (OMP)). This method is used as the basis to realize the uncertainty quantification (UQ) of radiated susceptibility and global sensitivity analysis (GSA) of input variables to output variables. GSA considers the influencing factors of the incident field and transmission-line geometric parameters. The global sensitivity indices of each input variable are calculated for varying impedance loads. The accuracy and efficiency of the proposed method are verified compared with the results of the polynomial chaos expansion based least angle regression method and Monte Carlo methods. [ABSTRACT FROM AUTHOR]

This paper intends to derive a detailed representation and attain a suitable computation method for the traction network. The transient analysis of the lossy multiconductor transmission lines (MTLs) is performed considering the electromagnetic characteristics of the rail track, which accounts for the frequency‐dependent and distributed nature of the line parameters over the entire frequency range for the traction network. Due to the practical difficulty in wideband parameter determination and the complex layout for the traction power supply system, the model implemented has been validated by comparison to several field tests that are carried out on a real high speed railway line for the purpose of identifying possible power quality problem. The good high representation of the frequency‐dependent parameter and the numerical solution will provide a reliable method for the transient analysis of the electrified railway. Afterwards, the transient calculation using vector fitting and modal decomposition is presented to evaluate how the emission is propagating along the MTLs of the electrified railways. Performing detailed and suitable analysis is necessary to determine the overvoltage conditions during the transients. The outcome of the analysis could be beneficial for the transient protection study in the electrified railway system. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Aiming at the crosstalk error of twisted-wire pair (TWP) caused by nonuniform pitch, this article innovatively uses Monte Carlo (MC) method to establish the probability distribution model of TWP with nonuniform pitch, and genetic algorithm-back propagation neural network is used to extract the unit length parameter of the transmission line. The chain parameter method is used to solve the multi-conductor transmission line equation based on the idea of cascade. Finally, the CST simulation results show that near-end and far-end crosstalk can be predicted effectively. In TWP modeling process, according to the probability distribution existing in the principle of stranding, the MC method is used to correct the probability distribution of the nonuniform pitch on TWP into a normal distribution. [ABSTRACT FROM AUTHOR]

This study presents the simultaneous signal and noise modelling and analysis of mm‐wave/THz high electron mobility transistors (HEMTs) in the linear regime as stochastic active multi‐conductor transmission lines (SAMTLs). For such devices, stochastic inhomogeneous telegrapher equations of SAMTLs are extracted assuming the domination of the quasi‐transverse electromagnetic mode. Analytical solutions for these equations do not exist. So a numerical analysis of such equations is introduced here at millimetre‐wave and terahertz frequencies. These equations are analysed with a numerical method in the time domain, namely the finite‐integration technique. A semi‐distributed model in the advanced design system commercial software is used to validate the numerical results. Also, the results of noise figure and scattering parameters (S‐parameters) for the metal–semiconductor field‐effect transistor transistor, which has the same SAMTLs model as the HEMT transistor, are compared with the measurement reports at microwave frequencies. [ABSTRACT FROM AUTHOR]

Modern transportation systems, such as aircraft, are increasingly replacing metal body parts for composite materials, such as carbon-fiber reinforced plastics. Despite the multiple advantages in terms of weight, size, and fuel consumption, this trend is posing a challenge for protection of cables against electromagnetic interference. Early risk assessment and optimization of cable design in modern aircraft require reliable methods that can quickly and accurately estimate crosstalk behavior in the presence of lossy ground planes. This article presents two novel methods to incorporate such lossy ground planes into the crosstalk modeling of cable bundles. The first method considers the ground plane as a discrete collection of cylindrical conductors. In the second method a ground impedance matrix is derived for lossy ground planes with a finite thickness. Results of both methods are compared to full-wave simulations and measurements, yielding excellent results in terms of accuracy and computation times. The discretized ground plane method is also applied to the case of wire pairs that are enclosed by two ground planes, both aluminum and carbon–fiber reinforced plastic, as a first step towards investigation of wiring that is embedded in thermoplastic material. Once more simulations and measurements are in good agreement. [ABSTRACT FROM AUTHOR]

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Nowadays, one of the most well-known methods for accurate simulation of the fast-transient phenomenon as well as the study and location of partial discharge (PD) in transformer windings is the method based on winding modeling. In this regard, the circular multi-conductor transmission line (CMTL) model, which is an improved model of the MTL model, has been proposed as the finest solution since it is acceptable in an extensive frequency range and it can investigate the effect of winding rotation by considering the radius and angle variables. However, one of the fundamental problems of using the CMTL model is that a set of large equations, known as complete admittance matrices, must be solved for all winding turns, which typically contain thousands of turns. To overcome this problem, we presented an improved RLC model, which has the same accuracy as the CMTL model in terms of frequency validity range and less computational complexity. In this model, the variables of length and curvature of the turns are also considered in the formulations. Although this method is theoretically accurate, its reliability method must also be determined in practice and how the PD signal propagation must be carefully considered due to the problems in high-frequency modeling of the winding. Numerical analyses and laboratory measurements resulting from the use of PD pulses on a 20 kV winding of a distribution transformer, as well as a 63 kV, 30 MV winding, revealed that a valid frequency range is extendable up to 5 MHz for the proposed improved model without a significant increase in computational complexity. [ABSTRACT FROM AUTHOR]

Rational function approximation is commonly used to fit the transmission line impedance over a wide frequency range. Nevertheless, it is computationally costly and challenging to implement in practical applications due to the high number of approximations required to fit the impedance curve for the high-frequency range. Therefore, a novel fitting method of multiconductor transmission line (MTL) based on the analytical impedance equation of a transmission line using the impedance frequency response measurement is presented in this paper. The proposed fitting method is a function of the transmission line length since it is based on the analytical impedance equation of a finite transmission line. Furthermore, the proposed model uses a constant set of equations and calculated parameters to fit the impedance frequency response for a wide range of frequencies. Moreover, the proposed model parameters are calculated using derived resonance equations and the impedance frequency response measurement. In addition, an algorithm is developed to further fit the proposed model to the impedance frequency response measurement of the transmission line. MTL impedance frequency response is measured using a real-time digital simulator (RTDS). To ensure the accuracy of the proposed model, a comparison between the proposed model and vector fitting (VF) is presented.

An efficient time-domain method based on the waveform relaxation with transverse partitioning (WR-TP) techniques and the delay extraction passive compact circuit (DEPACT) macromodel is presented for evaluating the electromagnetic (EM) transient response of multiconductor transmission lines (MTLs) excited by an external EM field. Firstly, the equivalent distributed sources due to the tangential components of the electric field are introduced into the MTLs equations. Then, the TLs are divided into a cascaded of DEPACT subnetworks, where the telegrapher's equations of lossless TLs are decoupled by applying the WR-TP techniques. And the relaxation sources over the lossy TLs are updated by using the waveform scaling algorithm, which can completely avoid performing the numerical convolution. Finally, the equivalent circuit is established and the transient responses induced on the lines can be obtained by using the circuit simulation software PSCAD. [ABSTRACT FROM AUTHOR]

Based on the theory of multi-conductor transmission lines (MTL), this paper proposes a new method for predicting and suppressing crosstalk of twisted-wire pair (TWP). The per unit length (p.u.l) RLCG parameters change caused by the inconsistent cross-sectional shape of TWP, changes in parameters make it difficult to solve the telegraph equation. In this paper, the method of transmission lines cascade is used. TWP is divided into several segments, and p.u.l parameters of each segment are predicted. Compared with before method, we propose a higher precision algorithm--beetle swarm optimization (BSO) to optimize the weights of back-propagation (BP) neural network, which predict p.u.l parameters at each segment. On this basis, it is divided into two steps: 1) Use MTL frequency domain method combined with lines' terminal conditions to solve crosstalk and compare with CST simulation results; 2) Use the singular value decomposition (SVD) method to add matrix modules at both ends of lines for suppressing crosstalk. The results show that proposed method in this paper is consistent with the simulation, and the accuracy is higher than before. [ABSTRACT FROM AUTHOR]

This article shows the advantages provided by implicit time stepping schemes for the study of multiconductor transmission lines. Implicit schemes allow for choosing time and space steps independently by attending only to resolution criteria, without the limitation imposed by the Courant–Friedrich–Levy stability condition. Hence, they behave favorably whenever a large time step would be preferable, for instance when a massive number of simulations is required for sensitivity analyses. We focus our attention on two common schemes in electromagnetics, Crank-Nicolson and Newmark-β methods, that are shown to have the same accuracy and to lead to the same solving-equation structure. We illustrate how to include frequency-dependent losses in the algorithms, and we show the influence of dispersion on fast transients. Results show that implicit formulations can be favorably compared with the classical explicit leap-frog scheme. [ABSTRACT FROM AUTHOR]

This paper presents an algorithm for predicting crosstalk in multiconductor transmission lines (MTL). Currently, crosstalk has an increasing impact on signal integrity. In the twisted pair cable (TPC), different rotation degrees correspond to different RLCG parameter matrices, these matrices are predicted by the beetle antennae search-back propagation neural network (BAS-BPNN) algorithm, and use implicit wendroff-finite difference time domain (IWFDTD) method to solve near-end and far-end crosstalk voltages. The CST simulation results show that near end and far end crosstalk can be predicted effectively. This proposed method is expected widely used in electronic applications for fast data transfer. [ABSTRACT FROM AUTHOR]

This paper investigates the effect of an external plane wave on a multi-conductor transmission line (MTL) located above a multilayer soil directly in the time domain. An improved finite-difference time-domain (FDTD) method is used, in conjunction with Vector Fitting (VF), to obtain the recursion relations of voltages and currents along the line by discretizing the equations in time and one-dimensional space. The source terms of the coupling equations are efficiently obtained in the time domain based on the Gaver-Stehfest algorithm. An equivalent model is also established in this work, where the geometry with three conductors is reduced to two conductors. Finally, some examples are presented to illustrate the effect of the soil and the plane wave on the transient. [ABSTRACT FROM AUTHOR]

6 IEEE ANTENNAS & PROPAGATION MAGAZINE APRIL 2021 6 IEEE ANTENNAS & PROPAGATION MAGAZINE APRIL 2021 Mahta Moghaddam Meisong Tong CHAPTER NEWS Chapter Activities, Humanitarian and COPE Initiatives, and Funding Updates Meisong Tong N ow behind us, 2020 was a year none of us will soon forget. Others in attendance included Prof. Debatosh Guha, Dr. Goutam Chattopadhyay, Prof. Jean-Marc Laheurte, Prof. Zhongxiang Shen, Dr. S.N. Joshi, Prof. Karl Warnick, Prof. Siddiqui, and Dr. Sudhakar Rao. Dr. Antar, Dr. Poddar, and Dr. Siddiqui spoke during the webinar, "Antennas for Wireless Communications and Other Applications: Recent Advances and Future Trends." Dr. Antar presented the presidential address, followed by speeches from Dr. Y.V.N. Krishna Moorthy, Dr. Rao, Dr. Surendra Pal, Dr. S.S. Karthikeyan, and Dr. Siddiqui. [Extracted from the article]

The degree adaptive stochastic response surface method is applied to analyze statistically the crosstalk in multiconductor transmission lines (MTLs). The coefficient of polynomial chaos expansion (PCE) is obtained based on the least angle regression. The truncation degree of PCE is iterated using the degree adaptive truncation algorithm, and the optimal proxy model of the crosstalk of the original MTLs that satisfies the actual error requirements is calculated. The statistical properties of crosstalk in MTLs (such as mean, standard deviation, skewness, kurtosis, and probability density distribution) are obtained. The failure probability of the electromagnetic compatibility in the MTLs system is considered. The global sensitivity indices of crosstalkrelated factors are analyzed. Finally, the proposed method is proved to be effective compared with the conventional Monte Carlo method. The uncertainty quantification of crosstalk in MTLs can be calculated efficiently and accurately. [ABSTRACT FROM AUTHOR]

We propose a broadband measurement method for measuring the electromagnetic (EM) properties of metamaterials in the 1-6 GHz frequency range. For this experimental technique, an original adjustable height strip transmission-line was developed that makes it possible to characterize metamaterials with different volumes and different numbers of unit cells. Therefore, it was possible to assess the influence of the number of unit cells in a sample on the measured constitutive parameters (complex permittivity and permeability). This study enabled us to define the criterion of the representative elementary number of cells. This criterion must be satisfied in practice in order to determine the microwave behavior for the sample under test in as close as possible to an infinite medium, whose EM properties can only be determined from simulations. Experimental and theoretical results for split ring resonator-type metamaterials are presented, compared, and discussed. [ABSTRACT FROM AUTHOR]

Underground cables such as pipe-type cables are widely used in urban power industry. In this study, an advanced thin-wire model of the pipe-type cables is 3D FDTD simulations. In this model, the multi-conductor cables are represented with two-level transmission line equations. A stabilising technique with a 1D spatial low-pass filter is proposed to maintain computational stability. Frequency-dependent losses are fully considered by using a vector-fitting technique. The proposed thin-wire model is validated with the multi-conductor transmission line theory analytically and the traditional FDTD method numerically. Good agreements are observed. It is found that the simulation maintains stability for 360,000-time steps. Compared to the traditional FDTD method, the memory space and computation time of the proposed model can be reduced by 73% and 98%, respectively. Induced lightning currents in a cable connection station are analysed. It is found that, without considering soil ionisation and soil stratification, the peak current in the metallic armour is 1.54 times as much as the one with considering these non-linear effects. It can be reduced by 9.04% and 18.6% if the cable is buried at depths of 1 m and 1.5 m, compared with the case of a 0.5 m buried depth. [ABSTRACT FROM AUTHOR]

─ To address the uncertainties of the radiated susceptibility of multiconductor transmission lines (MTLs), a surrogate model of the MTLs radiated susceptibility is established based on generalized polynomial chaos (gPC), and the gPC is made sparser by combining the adaptive hyperbolic truncation (AHT) scheme and the least angle regression (LAR) method. The uncertainties of the radiated susceptibility of transmission lines are calculated using the adaptive-sparse polynomial chaos(AS-PC)scheme. The parameters related to the incident field, such as elevation angle θ, azimuth angle ψ, polarization angle η, and field amplitude E, are inevitably random. Therefore, these four variables are taken as random input variables, and each of them is subject to different variable distributions. The MTLs model with infinite ground as the reference conductor is adopted, different impedances are used and the AS-PC scheme is combined with transmission line theory to calculate the average, standard deviation and probability distribution of the radiated susceptibility of MTLs. Sobol global sensitivity analysis based on variance decomposition is adopted to calculate the influence of random input variables on the MTLsradiated susceptibility model. The calculation results are compared with the results of the Monte Carlo (MC) method, proving that the proposed method is correct and feasible. [ABSTRACT FROM AUTHOR]

In this paper, a twisted-wire pairs (TWP) with random non-uniform twisting is established. It is divided into a complete pitch segment and a noncomplete pitch segment by the ratio between the pitch and the length. The randomness of the actual TWP cable is accurately simulated by the following methods: 1) random combination of complete pitch segments; 2) random combination of non-complete pitch segments; 3) random combination between 1) and 2). Based on the TWP model, an equivalent multi-conductor transmission lines (MTLs) model can be obtained. The neural network algorithm is introduced to describe the complex relationship between the arbitrary position of the TWP and the per-unit-length (p.u.l) parameter matrix. In addition, the crosstalk and the common-mode (CM) and differential-mode (DM) noise under field-to-wire coupling are predicted. The numerical results show that crosstalk and CM/DM noise in TWP cable are susceptible to the twisted pitch at high frequencies. Compared with full-wave simulation, the accuracy of the proposed method is proved. [ABSTRACT FROM AUTHOR]

The analysis of adjacent grounding systems under lightning currents which is responsible for many safety problems to human beings and damages to devices is very important. In this study, the behaviours of such grounding grids under lightning conditions which are not well documented in the literature are analysed using the multi‐conductor transmission line method in a two‐layer soil model. To achieve this goal, the expressions related to the study of a single grounding grid extracted from the recent study of the authors are developed to be appropriate to the analysis of adjacent grounding systems under lightning currents. Also, through the representation of the connectivity matrix, the analysis of the adjacent grounding grids with any size and degree of complexity is facilitated. Furthermore, the behaviours of the adjacent grounding grids under different lightning and soil characteristics are examined and some conclusions are derived. [ABSTRACT FROM AUTHOR]

The current study is aimed at investigating the exact location of partial discharge (PD) in coil insulation of a 6 KV/250 KW induction machine. Since measured PD signals have frequency components of kilohertz (KHz) to megahertz (MHz), it is necessary to employ fast and very fast transient models of electrical machines for locating PDs. In this study, a PD current pulse with MHz frequency component is injected to the multi-conductor transmission line model of each turn of the coil with frequency validity of >1 MHz. Considering coils as an interface between voltage source and finite element region, all circuit and field equations are rewritten to obtain the system final matrix, so that PD pulse is extracted. Experiment and simulation results show high accuracy of developed model to determine the exact location of PD. [ABSTRACT FROM AUTHOR]

This article presents a time-domain macromodeling algorithm for buried transmission lines subject to coupling of an incident field and terminated with linear and nonlinear loads. Different from overhead lines, the determination of the transient ground admittance is of great importance due to the complexity of the analytical expressions and the necessity of assuring a good approximation over a wide frequency range. The proposed macromodel adopts the analog behavioral modeling (ABM) library of Spice solvers to model frequency-dependent transmission line parameters directly, and calculate convolution in time domain, making it simple and convenient to treat time-domain field-to-line coupling equations without the need of time and spatial discretization and curve fitting used in other time-domain numerical algorithms. Besides, the model complexity is not limited by the line length. Hence, the proposed algorithm can significantly simplify the modeling process and improve simulation efficiency, especially for long multiconductor transmission lines. Furthermore, an effective and simplified expression for self and mutual ground impedance and admittance of underground lines is proposed in this article. With the proposed expression, the time-consuming numerical integration can be avoided, leading to a saving of 98% of the computational time. Finally, several validation examples of field coupling to buried power cables terminated with linear and nonlinear devices are investigated. The comparison of calculated waveshapes and CPU times shows the accuracy and efficiency of the proposed method. [ABSTRACT FROM AUTHOR]

A generalized multiconductor transmission line (MTL) model is integrated with the polynomial chaos stochastic Galerkin method (PC-SGM) in order to predict the stochastic response of a nonuniform multitwisted bundle of twisted-wire pairs (MTB-TWP) with random parameters, which is excited by random plane waves. The twist pitches of such nonuniform MTB-TWP are considered to be spatial stochastic functions, where its parametric equations are derived in their general form. Moreover, by taking the geometry deformation of the MTB-TWP cable into account, some of its parameters are represented by random variables, and the incident plane-wave fields can also be changed in some random ways. After that, the PC-SGM is applied to the stochastic telegrapher's equations in order to obtain deterministic ones that can be solved by using the MTL model. Therefore, the effects of the uncertainties of the parameters on the common mode and the differential mode currents are investigated in details, where, in each case, the probability density function is given. The results are validated in comparison with Monte Carlo (MC) method, where a very good agreement is obtained. It is shown that the PC-SGM simulation time is much smaller than that of the MC method as the number of random variables is relatively small. [ABSTRACT FROM AUTHOR]

Twisted wire used in complex systems has the ability to reduce electromagnetic interference, but crosstalk within the wire is not easy to obtain. This paper proposes a method to predict the crosstalk of multitwisted bundle of multi-twisted wire (MTB-MTW). A neural network algorithm based on back propagation optimized by the beetle swarm antennae search method (BSAS-BPNN) is introduced to mathematically describe the relationship between the twist angle of the wire harness and the per-unit-length (p.u.l) parameter matrix. Considering the symmetry of the model, the relationship between the unresolved angle of the BSAS-BPNN algorithm and the p.u.l parameter matrix is processed by using the multilayer transposition method. Based on the idea of the cascade method and the finite-difference time-domain (FDTD) algorithm in Implicit-Wendroff format, the crosstalk of the wire is obtained. Numerical experiments and simulation results show that the new method proposed in this paper has better accuracy for the prediction of the model. The new method can be generalized to the MTB-MTW model with any number of wires. All theories provide preliminary theoretical basis for electromagnetic compatibility (EMC) design of high-band circuits. [ABSTRACT FROM AUTHOR]

This paper presents a general formulation of the generalized multiconductor transmission line (GMTL) method to model a parallel cable harness including straight and bent wires. The parallel cable harness here indicates the uniform cross-sectional wire distribution. The GMTL equations are solved recursively based on the perturbation theory. This GMTL method facilitates an accurate evaluation of the current distributed on a cable harness. On top of that, the current obtained in a radiation problem is decomposed into two traveling currents, i.e., the positive-going and the negative-going currents, based on the least-squares method. With the decomposed currents, the steepest descent method is further adopted to achieve a fast approximation of the total radiated power. Finally, the capability and the limitations of the GMTL method in terms of the electrical wire separation and length are investigated. The necessity of the recursive corrections is also studied. [ABSTRACT FROM AUTHOR]

The improvement of the lightning performance of overhead distribution lines, hit by direct strokes, is investigated considering the use of additional shield wires beneath the phase conductors. The frequency-domain theory of multiconductor transmission lines with periodical grounding is adopted permitting a rigorous evaluation of the phase and shield wire currents and of the overvoltages across insulators. These can be minimized by careful positioning of the underbuilt shield wires. A sensitivity analysis on the overvoltages is conducted by varying either the position of the underbuilt shield wires and the grounding impedance. [ABSTRACT FROM AUTHOR]

In this paper, an approximate modeling approach called simplified multiconductor transmission line model (simplified MTL) is proposed for transient analyses of multiple grounding electrodes. Since this approach is in the frequency domain, the effect of soil dispersion (frequency variation of soil electrical parameters) is easily incorporated. In addition, the soil ionization effect is treated as gradually increasing radius of the electrode. With the use of this approach, predicting formulae for effective length of multiple grounding electrodes considering both ionization and dispersion are proposed for the first time. Finally, combining the extracted formulae with the apparent resistivity in two‐layer soils, effective length in such soils is easily predicted. [ABSTRACT FROM AUTHOR]

Classical multiconductor transmission line (MTL) theory, which is employed in electromagnetic transient (EMT) simulators, is built on the assumptions that the wire structure is infinitely long and has a uniform cross-section. Therefore, non-uniformities which occur in physical power systems, such as transmission line crossings, are not represented in classical MTL models. A new transmission line model has been developed to calculate space varying per unit length (PUL) parameter matrices near a conductor crossing using electromagnetic scattering theory. The proposed scattered field transmission line (SFTL) model has been implemented for lossless, frequency-independent conductors, that cross each other at a variable crossing angle. A single dimensional finite difference time domain (1D-FDTD) algorithm has been used to obtain the time-domain solution at each simulation time-step. Obtained results have been compared with those from a three dimensional (3D) full-wave electromagnetic solver. [ABSTRACT FROM AUTHOR]

In this paper, based on the research of back propagation (BP) neural network algorithm optimized by the beetle antennae search (BAS) algorithm, a new method for predicting stranded cable crosstalk is proposed. Firstly, the stranded wire model and the equivalent multiconductor transmission lines model are both established. Then, the extraction network of the stranded wire electromagnetic parameter matrix is constructed by using the BAS-BP neural network algorithm. Finally, the network is combined with the finite difference time domain (FDTD) method to solve the near end crosstalk (NEXT) and far end crosstalk (FEXT) of a specific three-core stranded model. The new method has good agreement with the crosstalk results obtained by the electromagnetic field numerical method. The validity of the new method is verified. [ABSTRACT FROM AUTHOR]

We describe a method for the broadband measurement of the even- and odd-mode propagation constants of symmetrical coupled transmission lines. The main advantage of the method, its simplicity, lies in the lack of need for four-port measurements. Only two-port measurements are required, and thus just a two-port vector network analyzer (VNA). The accuracy of the results can be increased at the cost of a higher number of measured coupled-line lengths. The new approach has been successfully applied for the determination of coupled microstrip lines in the 2- to 20-GHz frequency band in both simulated and experimental cases. A brief discussion about the repeatability of the microstrip launcher and the adverse effects of radiation is included. [ABSTRACT FROM AUTHOR]

The differential equations that model voltage and current for a multiconductor transmission line are written in matrix form. Supposing a time exponential solution through of the modal analysis the modal waves are obtained and solution of a ordinary matrix differential equation, thus determining the amplitude for voltage and current. The modal waves are given in terms of the fundamental matrix solution associated to the ordinary matrix differential equation. The decomposition of the modal waves in forward and backward propagators are used for determine the reflection and transmission matrices for junction in transmission lines. Circulant symmetric transmission lines are discussed, case in that the values for the self-impedance are the same as well as the mutual-impedance values and the same considerations to the admittance matrix. In particular, for these transmission lines are characterized the propagation constants and is observed that the number of multiconductors has effects only on a specific propagation constant. Numerical example of one multiconductor transmission line is presented allowing to observe important aspects of the methodology developed. [ABSTRACT FROM AUTHOR]

An accurate and efficient time-domain macromodeling algorithm based on the analog behavioral modeling (ABM) and generalized method of characteristics is proposed to calculate current and voltage responses of multiconductor transmission lines (MTLs) to incident field coupling. The proposed macromodel adopts the frequency response table of Laplace-domain elements in ABM library of Spice solvers to model the characteristic impedance (or admittance) and propagation operator of transmission lines and calculate the convolution in the time domain. Time-domain convolution is implemented by the solver, without the need of delay extraction and rational approximation for the MTLs solution. Compared with the existing algorithms for calculating the responses of incident field coupling to MTLs, the proposed algorithm largely simplifies the modeling and simulation process while ensuring stable responses, especially for long MTLs. Besides, it is also applicable and efficient to solve the case of nonlinear terminal elements, directly in the time domain. Several numerical examples of single conductor, two conductors, and three-phase 35 kV power transmission lines loaded with nonlinear metal oxide arresters are studied. The calculation results and CPU times are compared with those of other existing algorithms to validate the accuracy and efficiency of the method proposed in this paper. [ABSTRACT FROM AUTHOR]

High-speed interconnected channels, including printed circuit boards (PCBs) and high-speed connectors, are widely used in digital baseband communication systems. Connector degradation may lead to deterioration of the integrity of digital signals and is one of the major causes of low communication quality. In this work, the effect of electrical contact degradation on signal integrity was investigated using model analysis and experimental testing. A 3-D electromagnetic field model of a high-speed channel with a degraded contact surface was developed to evaluate transmission loss, signal reflection, and crosstalk. Using multiconductor transmission line theory and contact physics, a distributed parameter circuit model of a high-speed channel with a degraded contact surface was also developed. The electromagnetic field model results are in good agreement with those obtained from the distributed parameter circuit model. Both the electromagnetic field model and the circuit model results are validated using experimental tests. The results of this investigation provide a better understanding of the characteristics of signal transmission through a degraded contact surface in a high-speed channel and theoretical support for identifying failure features in fault diagnosis. [ABSTRACT FROM AUTHOR]

In this article, an efficient adaptive cross approximation (ACA) algorithm is employed for the lossy of MTL such as propagation matrix, attenuation loss, dielectric loss and characteristic impedance are evaluated. ACA solver is stable and convenient to solve the compression and approximation of low-rank matrix because adaptive refinement is used to generate the optimal mesh. The integral equation (IE) solver along with adaptive cross approximation (ACA) is used to reduce the computational time and memory size. In the proposed algorithm, the complexities become linear. Therefore, the ACA provides less memory size and less computation cost. The results are compared with the latest state of the art existing work for validation. [ABSTRACT FROM AUTHOR]

SUMMARY This paper presents improved algorithm for electromagnetic transient calculations on multiconductor transmission line (MTL) achieved by improvement of the time integration when forming a local system of equations for a finite element. Improvement of accuracy was obtained by using Heun's method. Previously developed local system of equations of MTL has been obtained using the generalized trapezoidal rule (ϑ‐method). The use of the generalized trapezoidal rule for the time integration sometimes causes numerical oscillations or numerical diffusion of numerical solutions. Numerical solutions obtained using Heun's method and using the generalized trapezoidal rule for different values of a time integration parameter are compared with analytical solution. It has been shown that Heun's method yields the results with much higher accuracy comparing to results obtained by generalized trapezoidal rule. [ABSTRACT FROM AUTHOR]

A volumetric negative-refractive-index transmission-line (NRI-TL) metamaterial is presented. This structure constitutes a natural extension of the planar NRI-TL metamaterials1 and maintains the desired features of broad bandwidth and low transmission loss. Unlike their planar counterparts, the proposed volumetric NRI-TL metamaterials can effectively couple incident plane waves from free space. The proposed topology can be readily made by stacking layers that are individually fabricated using standard multilayer printed-circuit board techniques at microwave frequencies. However, the creation of the volumetric structure results in the presence of a parasitic parallel-plate mode. This mode can interfere with the desired backward wave mode of the metamaterial, causing a stop band to appear. To facilitate the rapid analysis of this new design, a multiconductor transmission line model was developed. Through the use of this model and full-wave simulations, it will be demonstrated that this unwanted parallel-plate mode can be eliminated by properly arranging the vertical inductive loading wires. Using this process, it will be shown that a properly designed inductive load can result in a practical NRI metamaterial slab which is matched to free space over a large bandwidth (22%) and with low insertion loss (<-1 dB). This approach can also be used to design NRI-TL metamaterials with backward wave dispersion bandwidths of over 140%. [ABSTRACT FROM AUTHOR]

Through analyzing different cross-sections of the complex ball grid array (CBGA) sandwiched by silicon interposers, various distributed capacitances of the CBGA and the significance of the CBGA's coplanar capacitances are revealed. From the analyses, the composition of the CBGA's capacitance is found to have similarity with that of the coplanar waveguide's capacitance. Based on the electric-field coupling mechanism of the coplanar waveguide, geometrical analysis of the CBGA, and analysis of multiconductor transmission lines, analytical equations are derived to allow accurate modeling the equivalent circuit of the CBGA for 3D silicon-interposer packaging. The modeled equivalent circuit of the CBGA is validated with the full wave electromagnetic simulation, and it is demonstrated to have a good accuracy up to 40 GHz. Moreover, the CBGA structure can be further optimized for impedance matching with the guidance of the derived analytical equations. [ABSTRACT FROM AUTHOR]

• A -800 kV transmission line for neutral beam injector was design in this study, mainly about the insulating gap. • The ITER-like transmission line structure and coaxial structure both has been considered. • The simulation results shows that the coaxial has more advantages in terms of volume and electric field uniformity. • The design basis in accordance with specifications has been presented in the manuscript. The high-voltage transmission line carries electricity, water, and gas for the high-potential components in the NNBI system. High voltage transmission lines used in -800 kV acceleration grade NNBI systems require the transmission of multiple high voltages of different voltage levels. Its insulation design not only guarantees the reliability of insulation but also requires a small occupation volume. The FEA method is used for insulation design of multi-conductor transmission lines. In the design of -800 kV transmission line, coaxial and non-coaxial structures are mainly considered. In the case of SF6 filling space, conductor radius and conductor position are the main factors affecting insulation strength. Both structures can make its insulation strength meet the requirements. However, it is found that the coaxial transmission line is more compact and concise when it meets the insulation requirements, but it is difficult to install and maintain. [ABSTRACT FROM AUTHOR]

Integrating NbTiN-based microstrip tuning circuits with traditional Nb superconductor-insulator-superconductor (SIS) junctions enables the low-noise operation regime of SIS mixers to be extended from below 0.7 to 1.15 THz. In particular, mixers incorporating a NbTiN/SiO2/NbTiN microstrip tuning circuit offer low-noise performance below 0.8–0.85 THz, although their sensitivities drop significantly at higher frequencies. Furthermore, a microstrip geometry in which NbTiN is used as the ground plane material only (NbTiN/SiO2/Al) yields significant improvements in the sensitivities of SIS mixers operating up to 1.15 THz, with an upper operating frequency that depends upon the quality of the NbTiN layer, and thus its deposition process. Films deposited at room temperature have Tc=14.4 K and ρn,20 K∼60 μΩ cm, and offer low-noise performance up to 1 THz, whereas films deposited at 400 °C have Tc=16 K and ρn,20 K∼110 μΩ cm, and offer low-noise performance up to 1.15 THz. Taken together, these results demonstrate that the high-frequency surface resistance of a NbTiN layer depends upon the film’s structural properties. Most significantly, the drop in performance that is seen at F>1 THz in mixers incorporating NbTiN ground planes deposited at room temperature is attributed to nonhomogeneities in the structural and electrical properties of these films, as is the poor performance of mixers that incorporate NbTiN wiring layers at F>0.85 THz. The development of these NbTiN-based microstrip tuning circuits will enable the production of low-noise SIS mixers for the 0.8–0.96- and 0.96–1.12-THz frequency bands of the Heterodyne Instrument for the Far Infrared on board the European Space Agency’s Herschel Space Observatory. [ABSTRACT FROM AUTHOR]

This work is devoted to the research of new asymmetry effects in symmetric protective structures with triple modal reservation. We analyzed the structures with different cross-sectional locations of the reference conductor: in the center (unshielded structure), around (shielded structure), at the top and bottom (multilayer printed circuit board), and in the form of side polygons (double-sided printed circuit board). First, a preliminary quasi-static simulation was performed in the range of parameters. It was revealed that in all structures, except for the shielded one (in the form of a cable), the deviations of the output voltage amplitude, bandwidth, and frequency of the first resonance were insignificant, whereas in the shielded structure there were significant deviations in the time and frequency responses. The attenuation of the output voltage in relation to the input for each structure was also estimated. In addition, we performed a parametric optimization of the structures under consideration using a heuristic search, which made it possible to improve their characteristics. Finally, the switching order between the conductors in these structures with the original and optimized parameter sets was investigated in detail. The optimal conductor switching order in the case of a component failure was determined, and the best (according to protective characteristics) parameter configuration for each structure was found.

For early risk assessment in the design of cabling in an aircraft, as well as cable bundle optimization, efficient crosstalk estimations, and dependency of crosstalk with respect to designable parameters are required. A low-frequency technique for analyzing crosstalk in multiconductor transmission lines is presented. The result of this analysis is a closed-form expression for crosstalk in a specific cabling configuration. The technique has been validated via measurements and is used in two examples comprising two wire pairs close to a ground plane and in free space. Low-frequency closed-form expressions for near-end crosstalk are derived for both situations, which directly relate any designable parameter to crosstalk levels. Moreover, these expressions clearly show differences between the cases with and without a ground plane. Specifically, with the ground plane, the decrease in crosstalk when doubling the separation distance is 24 dB for pairs close to the ground, while it is 12 dB in free space. The closed-form expressions are utilized to create an overview of sensitivities of crosstalk to all designable parameters for both configurations. Finally, the low-frequency approximations of the chain parameters are applied to more complex nonuniform transmission lines, yielding more than 20 times faster computations when compared with complete MTL simulations. [ABSTRACT FROM AUTHOR]

A transformer white box model based on multiconductor transmission line (MTL) theory in cylindrical coordinates has been developed. This model allows variable lengths in conductors to be incorporated into the MTL formulation. A 2D axisymmetric model for the windings is implemented using finite element method (FEM) to determine the per unit length capacitance and inductance matrices. The model is capable of producing voltage and current results in both the frequency and time domains for each turn in the winding. The results obtained using the proposed model has been compared with those from Numerical Electromagnetic Code (NEC) and measurements done by others. Applications of the proposed model in analyzing inter-turn voltages and the induced voltages on secondary windings have been investigated. [ABSTRACT FROM AUTHOR]

In this paper, a model of aerial multiconductor transmission lines with frequency-dependent electrical parameters for the simulation of time-domain electromagnetic transients due to incident electromagnetic fields is presented. The frequency dependency of the electrical parameters is taken into account using the penetration impedance; this allows applying the method of characteristics without having to resort to modal transformations. With this alternative approach, transforming the transmission line partial differential equations to ordinary differential equations is performed in the phase domain, which simplifies the mathematical development of the method and also the numerical solution. The validity of the proposed model is shown with five study cases involving different transmission systems and excitations. [ABSTRACT FROM AUTHOR]