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1.
This paper presents a comprehensive analysis of the numerical anisotropy and dispersion of 3-D TLM meshes constructed using several generalized symmetrical condensed TLM nodes. The dispersion analysis is performed in isotropic lossless, isotropic lossy and anisotropic lossless media and yields a comparison of the simulation accuracy for the different TLM nodes. The effect of mesh grading on the numerical dispersion is also determined. The results compare meshes constructed with Johns' symmetrical condensed node (SCN), two hybrid symmetrical condensed nodes (HSCN) and two frequency domain symmetrical condensed nodes (FDSCN). It has been found that under certain circumstances, the time domain nodes may introduce numerical anisotropy when modelling isotropic media 相似文献
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In TLM modelling of lossy systems, instead of concentrating losses in lumped resistors or stubs, an attempt is made to model the losses as distributed, in the `connect' or `propagate' stage, while leaving the scattering lossless. TLM transmission and reflection coefficients are derived using a novel, distributed, quasi-black box approach. The coefficients agree with those from lumped resistor analysis. The implications are discussed in the context of lossy TLM modelling in general 相似文献
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A method for using the transmission line modelling (TLM) 2-D series node for modelling TE modes in dielectric and lossy media is investigated. This method preserves the standard voltage-electric field analogy in TLM. Good agreement between the series node and other methods is achieved.<> 相似文献
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A transmission line matrix (TLM) algorithm for the effective solution of arbitrary guided wave problems is proposed. The algorithm uses an appropriately transformed symmetrical condensed node (SCN) introduced herein. In comparison with the previous SCN TLM formulation for the analysis of guiding structures, the approach maintains equivalent accuracy and generality while providing a 50% gain in terms of required computer memory and time. The advantages of the new algorithm are verified by means of several examples, including full-wave analysis of waveguides filled with anisotropic and lossy media 相似文献
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A study of the symmetrical condensed TLM (transmission line matrix) node is presented. The study reveals not only that the characteristic scattering matrix satisfies the law of conservation of energy but also that electromagnetic fields are conserved even for finite node spacing. Using the results of this study, the authors develop an efficient algorithm for TLM analysis using the symmetrical condensed node. This algorithm significantly reduces the number of floating point operations so that the speed of computation is comparable to that of other expanded node analysis schemes. The case of a lossy medium is also discussed. With a better understanding of this symmetrical node and equipped with a fast algorithm, TLM analysis of three-dimensional electromagnetic problems can improve the computer-aided design of microwave and millimeter-wave circuits 相似文献
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An efficient method for the suppression of excitation-induced spurious modes in the symmetrical condensed node (SCN) transmission-line matrix (TLM) method is presented for the general case of dielectric, anisotropic, or lossy media in planar structures. A special mapping of the field-excitation onto the wave amplitudes of the TLM algorithm completely prevents the emanation of the spurious modes. The application of the mapping in the k-ω space can be done for waveguides with low computational effort. The method is generalized for planar structures with high spatial frequencies of the field at the discontinuities. We use precomputed field templates at the entrance of the three-dimensional (3-D) structures. The mapping is mainly done in the space domain based on the quasi-TEM propagation of the guided waves to keep the computational effort low. Instead of the four-dimensional (4-D) k-ω transformation, only independent one-dimensional (1-D) transformations to the wave coefficient of the conductors direction and ω are necessary. In the case of propagation with low dispersion, the expenditure can be further reduced to 1-D transformations with respect to ω. The efficiency of the present method is demonstrated by investigation of a coplanar waveguide and a triplate waveguide 相似文献
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A general SPICE-transmission-line matrix (TLM) interconnection framework has been developed. The connection algorithm is based on the representation of the TLM network by equivalent Thevenin and/or Norton sources. Fundamental issues such as source equivalence and SPICE-TLM interconnection options have been examined. The framework opens new and far-reaching possibilities for hybrid global microwave and high-speed digital circuit modeling in the time domain because it combines the extensive circuit and device models of SPICE with general three-dimensional field solutions. 相似文献
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The properties of a TM010 cavity containing a lossy dielectric material are investigated, using the transmission-line-matrix (TLM) technique with serial nodes in cylindrical coordinates. The cavity operates at 1.1 GHz and has three concentric layers and an air gap between the sample and cavity cover. The influence of this air gap on the Q -factor and the resonant frequency is studied. Compared with the TLM method in rectangular coordinates and uniform grids, the present method is more efficient and easier to program for the analysis of the cavity with cylindrical symmetry. Computed results show that the air gap between the sample and cavity cover is very critical to the accuracy of the measurement of the dielectric property of the sample when the sample diameter is small, but negligible when the diameter is large. Unfortunately, in the case of a highly lossy sample, a small sample diameter must be used to maintain a reasonably high Q -factor. Special techniques are recommended to minimize the error caused by the air gap 相似文献
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Both in the transmission line matrix (TLM) and the finite difference time domain (FDTD) methods, absorbing boundary conditions (ABCs) are used to truncate the computational domain for the simulation or open boundary problems. A comparison of the performance of ABCs applied to TLM and FDTD is presented. The results indicate a significant improvement in the performance of an ABC when applied to TLM compared to the performance of the same ABC when applied to FDTD. An explanation for this improvement in the performance is given 相似文献
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This paper describes the principles underlying a library of single and coupled lines, ideal or lossy for the cad of interconnections in gigabit logic circuits. The models are based upon the quasi-TEM approximation, they exploit the method of characteristics and direct simulation in the time domain which give good calculation efficiency. The modeling of lossy coupled lines is original and utilizes modal decomposition in the time domain which may be performed in good approximation for coupled lines of equal widths. The models are integrated in the circuit simulator Macpro to perform the cad of circuit microstrip interconnections. Simulations including the response of the instrumentation are compared with the corresponding measurements on typical configurations of lossy coupled lines deposited on a semi-insulated GaAs substrate. 相似文献
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SoC system designers commonly employ SystemC based Transaction level modeling (TLM) for its early software development usage and its analysis capabilities. TLM helps in realizing a SoC using virtual prototyping by integration of SoC components at different abstraction levels. The TLM 2 standard introduces interoperability rules for the models that may have been developed independently. However, neither SystemC compiler nor TLM library supports checking of such rules and manually debugging interoperability errors in such models could be a major problem. This provides motivation for developing automatic compliance checking techniques which can detect and report such errors. As the models are refined to incorporate detailed intercommunication protocols among the system components, the need for compliance checking extends to these protocols as well. In this paper, we present an efficient UML based compliance checking technique for TLM 2 models which supports static, dynamic and protocol-specific rule checking. 相似文献
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Simons N.R.S. Sebak A.-R. Bridges G.E. 《Geoscience and Remote Sensing, IEEE Transactions on》1995,33(3):759-767
The problem of scattering and radiation in the presence of a material half-space is solved using the transmission line matrix (TLM) method. The TLM method is a general numerical method for obtaining an approximate solution to the time-dependent form of Maxwell's equations in the presence of complex environments. The method requires the discretization of the entire spatial domain of the problem and provides the transient response as well as (through discrete Fourier transform) the frequency domain response. The three-dimensional symmetric-condensed TLM node is applied. A total/scattered field formulation is applied to excite the space. The source used is an electrically short electric dipole and is described analytically in the time-domain. The method is used to calculate near field distributions (in both the time and frequency domain) and the change in source input impedance of a dipole radiator in the presence of a half-space. Numerical simulations relevant to the detection of buried objects are provided 相似文献
15.
Hoefer W.J.R. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1991,79(10):1459-1471
A time domain technique based on equivalent transmission line interconnections, referred to as the transmission line matrix model (TLM), is presented. The author retraces the history of TLM, from the original concepts of Huygens to the pioneering work of Peter B. Johns, and on to the latest developments in TLM modeling. The most important two-dimensional and three-dimensional TLM algorithms are explained, and new concepts in time-domain representation of frequency-dispersive boundaries are discussed. Some typical applications are described 相似文献
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本文针对线天线及天线阵的频域分析方法的缺点,首次将时域传输线矩阵法应用到这一领域,应用时域TLM法时,只需经过一次运逄就可以得到天线及天线阵各个区域的场特性,本文计算方法及数值结果表明,运用时域TLM法可以对各种大型天线阵进行有效的分析,便于工程应用。 相似文献
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Chih-Ping Chang Chang-Fa Yang 《Electromagnetic Compatibility, IEEE Transactions on》2005,47(4):723-730
In this paper, a moment method (MM) solution for analyzing the electromagnetic (EM) shielding properties of three-dimensional (3-D) lossy dielectric and magnetic objects over a lossy half space is presented. An MM, based on a volume formulation and a special Green's function in the spectral domain, is developed. Plane waves with TMz and TEz polarizations incident upon 3-D lossy material structures are demonstrated for the shielding effects of those bodies in the presence of a lossy ground. Some of the results are compared with those evaluated by applying the finite difference time domain method, and good agreements are obtained. The MM solution can be used to study the shielding problems for 3-D objects located above a lossy ground. 相似文献
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Jifu Huang Ke Wu 《Microwave Theory and Techniques》1995,43(10):2472-2477
A generalized transmission line matrix (TLM) formalism is proposed for unified simulation of wave propagation problems. The present modeling is made possible with a new TLM node that is derived to account for simultaneously the electromagnetic effects of permittivity and permeability tensors of material. It is shown, through numerical examples, that the new node-based TLM algorithm in the frequency domain can be used to solve a large class of complex electromagnetic problems ranging from microwave circuits to optical devices. A dynamic solution for the r-cut sapphire-based microstrip is presented that highlights its application to high-temperature superconducting microwave circuits 相似文献
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《Electron Devices, IEEE Transactions on》1987,34(3):650-658
Analytical and numerical techniques to study the pulse propagation characteristics such as delay, distortion, and crosstalk in multilevel interconnections associated with high-speed digital IC's including VLSI chips are presented. The parallel and crossing interconnections at various levels are modeled as lossy coupled lumped distributed parameter systems, which are analyzed for their time domain characteristics. The characterizing electrical parameters of the structures are computed by utilizing the network analog method that has been formulated to solve for the lossy line constants and parasitic coupling associated with a three-dimensional multiconductor system in a layered lossy medium. It is shown that the time domain response of the multiport structures can be computed by using standard CAD programs such as SPICE by utilizing compatible circuit models developed from the solution of such systems. Examples of the step and pulse response of typical systems are included to demonstrate the versatility, usefulness, and accuracy of the techniques presented in the paper. 相似文献