多导体传输线瞬态响应研究

针对多导体传输线瞬态响应的无源性问题,提出了基于集总等效源模型的多导体传输线瞬态响应模型. 从外场激励下的多导体传输线的频域电报方程解出发,将外场在传输线上激励的分布电压源和电流源与传输线指数矩阵解耦,建立了集总等效电压源和电流源模型. 为避免复杂的傅里叶反变换及卷积运算,推导了集总源模型的时域递推方程. 在此基础上,采用时域有限差分法建立了端接线性负载、非线性负载和外场激励下的不等长多导体传输线瞬态响应离散递推方程. 通过对无损传输线的仿真对比,验证了方法的有效性. 最后,对端接线性负载、非线性负载和外场激励下的不等长多导体传输线瞬态响应进行了试验和仿真分析.       

A Hybrid Electromagnetic-Circuit Method for Electromagnetic Interference Onto Mass Wires

A current decomposition method is proposed for the analysis of field coupling to mass wires near complex structures. The foremost attribute of the method is the decomposition of the current on each wire into push-pull and push-push mode currents. The former refers to the perturbation current accounting for the interactions among the wires within the bundle, whereas the latter represents the interactions between the mass wire bundle and the surrounding structure. Multiconductor transmission line theory is employed to compute the push-pull mode current by using one of the wires in the bundle as the return/reference conductor. Current induced on a test wire located along the reference line is used to compute the push-push mode. For this analysis, we employed the method of moments for the electromagnetic analysis of surrounding structure and simulation program with integrated circuit emphasis (SPICE)-like simulators for the analysis of a circuit model of the transmission lines extracted via the partial element equivalent circuit method. Several validation examples (including transmission lines inside an automobile) are presented. It is also shown that the traditional transmission line theory based on quasi-static analysis fails with increasing complexity of the surrounding structure.     

Investigation of Crosstalk and Coupling Effects of Incident Plane Waves in Orthogonal Microstrips in High-Speed Integrated Circuits Using Full-Wave and Quasi-Static Methods

The crosstalk and coupling of the external fields on orthogonal microstrip transmission lines in different layers have significant effects on signal quality in MMIC and PCBs. In this paper the crosstalk is analyzed in detail using both full-wave and quasi-static methods. The used full wave method is mixed potential integral equation method of moment (MPIEMoM). Because of the weak coupling between lines, the effect of the incident plane-wave is studied by applying transmission line theory in a scattered voltage formulation uses quasi-TEM propagation model for each interconnection and the exact distribution of the incident electric field within the layers. Afterward, by using the predetermined lumped circuit model of the cross-region, the effect of coupling between two lines is calculated and then applied to terminal voltages in 1–20 GHz frequency range which results in the final terminal voltages.     

Analyzing electromagnetic pulse coupling by combining TLT, MoM, andGTD/UTD

An important problem in electromagnetic compatibility (EMC) analysis is to determine the coupling of an electromagnetic field into a shielded cable. Using the transmission line theory (TLT), the disturbance voltage induced inside the cable is easily calculated from the current distribution on its shield. This current distribution depends on the incident electromagnetic field and is efficiently determined by the method of moments (MoM). Extending the MoM with the geometrical and uniform theory of diffraction (GTD/UTD) makes it possible to solve scattering problems that are too large and too complex for the plain MoM. The combination of the three approaches-TLT, MoM, and GTD/UTD-allows calculation of the disturbance voltage inside a shielded cable, which is part of a complex scattering structure. The fundamentals of each method and the way of putting them together are shown in this paper. The application of the proposed method is demonstrated by an example: the pulse coupling between a monopole antenna and a shielded cable is analyzed, taking into account a large conducting structure in the vicinity     

Enhanced Periodic Structure Analysis Based on a Multiconductor Transmission Line Model and Application to Metamaterials

We propose to model periodic structures by equivalent multiconductor transmission lines (MTLs). The developed technique is based on a multimodal representation of the periodic structure unit cell, such as required for periodically loaded MTLs and periodically loaded waveguides with higher order evanescent mode interaction between cells. Compared to commonly employed periodic structure analyses which only provide the dispersion diagram, the proposed method provides all the parameters needed to accurately model the excitation and matching of finite-size periodic structures. The usefulness of the method is illustrated by means of two examples of negative-refractive-index metamaterials. First, a loaded MTL known as the shielded mushroom is analyzed. The proposed technique allows addressing the fundamental issue of the excitation of the different propagating Bloch modes supported by such a structure. Second, a split-ring resonator and wire metamaterial is analyzed. The method is shown to accurately represent the coupling between cells, thereby providing an enhanced design tool compared to the dominant-mode analysis usually employed for this type of metamaterials.      

An efficient algorithm for the calculation of parasitic couplingbetween lines in MIC's

A new algorithm is developed to calculate parasitic coupling between transmission lines in an efficient manner. The algorithm works by using the currents and voltages on the lines in the absence of parasitics to calculate independent voltage and current sources which then give the approximate coupling strength between the various lines. These sources are easy to place in a CAD circuit program. The algorithm is demonstrated on a double-stub filter structure. The observed splitting of the resonance, for this particular example, is modeled by using dependent sources, as calculated from the independent sources     

Time-domain solution of field-excited multiconductor transmissionline equations

Analytical solution of lossless field-excited multiconductor transmission lines is presented. The equivalent circuit of a multiconductor transmission line with distributed sources is reduced to a simple lumped parameter circuit with independent voltage sources at both the ends of the transmission line. The transient source waveforms are analytically estimated for exponential time dependence of the external field, as EMP, ESD, and lightning. The method is suitable for a direct implementation in computer-aided circuit analysis codes and enables a very fast analysis for any load condition. Some numerical results are presented for single conductor and multiconductor lines excited by all EMP plane-wave field     

Circuit-Based Analysis of Electromagnetic Field Coupling With Nonuniform Transmission Lines

This paper presents a new algorithm for simulating electromagnetic (EM) field coupling with nonuniform multiconductor transmission lines in a circuit simulation environment. The proposed algorithm is based on the concept of passive model-order reduction, whereby an algorithmically developed passive reduced-order model, coupled with a set of equivalent sources representing the incident filed, are shown to accurately capture the behavior of the transmission line under EM excitation. The reduced-order model is developed independently from the particular shape of the incident field pulse, in the sense that, in constructing the model, one does not need prior knowledge about the waveform of the incident pulse of the EM field. In addition, it is also shown that the model developed can be used to simulate the transmission line in the absence of the EM field. The derived equivalent sources, representing the field coupling, are given directly in the time domain, thereby making simulation under nonlinear circuit terminations an easy task. Although the proposed work is aimed mainly at simulating nonuniform transmission lines, it can be applied to uniform lines as a special case. The proposed algorithm has been validated numerically with several examples.     

一种分析含受控源电路的去耦等效法

分析含受控源电路是电路分析中的一个难点，尤其在用等效变换法化简电路时，因被控制支路对控制支路有依赖关系，使元件或支路不能合并化简，为此，提出了一种分析含受控源电路的去耦等效方法。由分析得出：在线性网络中，受控源支路一般可去耦等效为一个实际电源或电阻(在相量电路中为阻抗)；对于不包含独立源的线性一端口网络，受控源支路能去耦等效为电阻(在相量电路中为阻抗)。在对受控源去耦等效之后，电路模型中无受控源元件，因而化简后的电路不再受控制量的制约。     

MoM-FDTD hybrid technique for analysing scattering problems

The authors present a new hybrid technique for analysing complex electromagnetic problems, combining a progressive version of the MoM and the FDTD. The use of the equivalence principle allows the problem to be separated into two simpler problems, and a proper set of equivalent sources is defined to account for the coupling between actual sources and scatterers     

Simple technique for representing slots in cavities

Determining the coupling of electromagnetic fields into cavities via slots can be complex. This letter presents a simple technique of achieving this. The method utilises a superposition of coupling via a series of circular apertures that represent the equivalent slot. The series of apertures are all transposed to single position allowing the slot to be represented by a single circular aperture. A model for coupling via a slot is realised using intermediate level circuit modelling that yields credible results and is validated against a transmission line matrix model.     

不等长非均匀有损耗传输线FDTD瞬态分析

以分析等长均匀无损耗多导体传输线的时域有限差分(FDTD)法为基础,在考虑传输线损耗的情况下,对不等长非均匀多导体传输线进行分析。首先,在考虑传输线损耗的情况下给出传输线上各点电压和电流的迭代计算公式;其次,利用该公式对不等长非均匀有损耗传输线模型进行数值计算和理论分析;最后,通过仿真实验,其结果表明所提计算方法是正确和有效的。该方法对不等长非均匀有损耗传输线的研究提供理论计算参考。     

Transmission line models for lossy waveguide interconnections in VLSI

At high frequencies the waveguide nature of interconnections in VLSI circuits becomes important. Moreover, losses in interconnection are a major feature, not a perturbation. Here it is shown that even for such lossy waveguide structures an exactly equivalentRLGCtransmission line can be found. Equations are given determining these transmission line parameters in terms of the waveguide propagation constant and complex average power, and also in terms of integrals over the electric and magnetic field varibles. The resultingL,C, andGparameters differ from the usual static values when losses are important, and R is not restricted to the usual formula based upon a perturbation treatment of the skin effect. Consequently, semiconductor substrates can be treated. "Current" and "voltage" are found to have an abstract meaning in the equivalent transmission line. For a waveguide in a medium where conductivity and permittivity vary with position (such as a many-layered medium) an explicit formula relating "current" and "voltage" to weighted averages of transverse waveguide fields is given. A brief discussion of the reformulation of Thevenin equivalent circuit parameters in terms of reflection coefficients avoids terms such as "open circuit voltage" that are difficult to interpret for the equivalent transmission line. The framework presented allows construction of equivalent circuits for lossy waveguide interconnections, drivers, and terminations that provide correct spatial dependence in the direction of propagation and correct power relations despite the abstract nature of "current" and "voltage" in these lines.     

S-parameter measurements yielding the characteristic matrices ofmulticonductor transmission lines

A frequency-domain method is presented, which yields accurate characteristic matrices of uniform multiconductor transmission lines (MTLs). It uses simple two-port network analyzer S-parameter measurements of a set of open-circuit and short-circuited MTL configurations. The method eliminates the need for voltage and current probes, which introduce errors. Transversely inhomogeneous MTLs can be accurately characterized in their quasi-TEM propagation regime. The influence of the skin effect on the inductance matrix is taken into account. The technique was used to determine the inductance and capacitance matrices of a low-loss three-conductor ribbon cable above a ground plane. Comparisons with numerically and analytically obtained data are given. Measurements are found to be repeatable for lines of length ℒ<λ/4. The λ/4 requirement is not found to be a restriction in the megahertz regime and only plays a role as line-end effects become significant at gigahertz frequencies. The obtained accuracy is significantly better than previously reported results     

Essential-coupling-path models for non-contact EMI in switching power converters using lumped circuit elements

This paper proposes a simple lumped circuit modeling approach for describing noncontact EMI coupling mechanisms in switching power converters. The resulting model assumes a minimum number of noise sources and contains essential coupling paths that allow easy physical interpretations. Essentially, all capacitive couplings are represented by an equivalent noise voltage source and six coupling impedances, whereas all inductive couplings are represented by an equivalent noise current source and three coupling impedances. The resulting coupled noise appears as currents flowing into the terminals of the line-impedance-stabilization-network (LISN). The equivalent voltage source can be conveniently approximated as the switching-node-to-zero voltage, which is typically a rectangular pulse of a few hundred volts. The equivalent current source can be modeled as the current flowing around a loop containing the equivalent voltage source and parasitics such as winding capacitance of the power transformer, the snubber capacitance and connection inductances. Also, the coupling impedances can be estimated by making simplifying assumptions about the geometry of the components and tracks, or by direct measurements. Simulations and experiments verify how inductive and capacitive couplings through each path may produce substantial EMI measured by the LISN. Being based on a lumped circuit approach, the proposed model is easy to apply in practice for understanding, diagnosing and approximating EMI behaviors.     

Electromagnetic coupling between wires inside a rectangular cavityusing multiple-mode-analogous-transmission-line circuit theory

This paper examines the coupling between two arbitrarily positioned wire segments inside a rectangular enclosure. The enclosure is treated as a superposition of analogous transmission lines which have been short circuited at two positions on the propagation axis. Each analogous transmission line is associated with a particular waveguide mode in the cavity. Previous work has used this analogy to predict the coupling between two monopoles inside a small box using the dominant TE ₁₀ mode. This paper considers the general case of high-frequency coupling between two wire monopoles in a large rectangular cavity, where several higher order modes are active. By taking into account higher order modes, and the mutual coupling between the modes, a simple equivalent circuit is presented which can give a prediction for the coupling between the monopoles. Experimental results for various monopole pair positions are shown, which indicate the success of the multimode theory. The technique requires far less computer resources than traditional methods for solving such a problem (e.g., MoM, TLM or FDTD), with solution times of less than a second on an average PC. In addition, considerable insight into the coupling process can be gained by including or excluding particular waveguide modes. This is not possible with numerical methods     

耦合型漏泄同轴电缆传输和耦合特性研究

针对泄漏同轴电缆作为分布式传感器应用于物联网和智能家居的室内安防入侵检测时，运用全波仿真软件HFSS不能有效仿真长距离的耦合漏缆的问题，提出了一种等效电路模型.利用参数提取软件，先提取单个开槽的缝隙单元的等效电路模型，然后借助于传输线理论，利用四个传输矩阵级联得到整段漏泄同轴电缆的传输矩阵.并考虑两根漏缆缝隙间相互耦合，提出了表征耦合特性的等效电路模型.将等效电路模型利用商用软件高级设计系统（advanced design system，ADS）进行电路搭建与仿真.仿真结果表明，本文提出的两根漏缆的等效电路模型与全波仿真结果非常符合，可以快速地仿真长距离的耦合漏缆结构，并大大节约了仿真时间.     

Quasi-TM MoL/MoM approach for computing the transmission-line parameters of lossy lines

This paper presents a quasi-TM approach for the fundamental mode of transmission lines with semiconductor substrates and nonperfect metallic conductors. The approach has allowed us to develop a transmission-line model by properly defining frequency-dependent parameters in terms of the quasi-static electric potential and the electric current density along the propagation direction in the line. The previous quasi-TM analysis avoids the involved numerical root finding process typical in full-wave analysis, and overcomes the limitations of the conventional quasi-TEM approach to account for the effects of the longitudinal currents present both in the lossy substrates and in the nonperfect conductors. The transmission-line parameters have been computed by a hybrid technique that combines the method of lines with the method of the moments (MoM). The total CPU effort has been considerably reduced thanks to the possibility of finding closed-form expressions for the reaction integrals appearing in the MoM. Comparisons with previous computed and measured results show the validity of the present model.     

分层介质电,磁流场,位谱域并矢格林函数的统一形式

利用谱域导抗法推导分层介质的电磁流场位并矢格林函数积发量的统一的表达式。在谱域中通过坐标旋转，得到了两组独立的等效传输线，这样问题转化为求２解等效传输线的电流与电压，因而对于这类问题用一个统一的传输线公式即可得到各种情况的解，从而使推导变得非常简便。推导中考虑到单轴各向异性介质的情况，各向同性介质可以作为它的特例。     

带状线低通滤波器的等效电路模型研究

所涉及的滤波器结构中包含开路端、T型接头等不连续性部分,因此在分析时应充分考虑到这些不连续部分所产生的传输损耗。基于传输线基本理论和矩量法(MoM),通过曲线拟合获得了偏心带状线开路端电容的解析公式,然后依据已有的微带线不连续性等效电路理论,提出了偏心带状线低通滤波器的等效电路模型。经实例验证发现,所得模型的计算结果与IE3D软件仿真结果吻合良好,而传输线理论法未考虑上述传输损耗,计算结果存在明显偏差。