Computation of frequency-dependent propagation characteristics ofmicrostriplike propagation structures with discontinuous layers

A general procedure based on the method of lines is presented for the full-wave analysis of propagation structures having layered substrates with step inhomogeneities in each layer. Examples of such structures include microslab lines and microstrip near a substrate edge. It is shown that with this extended method of lines technique the frequency-dependent characteristics, including the modal impedance, current distribution, and other properties of these structures, can be calculated. To illustrate the technique, typical structures such as microstrips on a finite-width dielectric slab and microstrips near a substrate edge are considered, and the effect of the proximity of the edge on the propagation characteristics of the microstrip is computed. For the case of a microstrip near a substrate edge, the numerical results obtained are compared with measured values of propagation constants, showing that the proximity effect is predicted to within 1%     

Dispersion characteristics of square pulse with finite rise time insingle, tapered, and coupled microstrip lines

The distortion of an electrical pulse, with finite risetime (quadratic-linear-quadratic transition) caused by dispersion as it propagates along a uniform microstrip, a tapered microstrip and a coupled pair of microstrips is investigated. Closed-form analysis equations for single and coupled microstrips are used to find the frequency-dependent phase velocities. Results are presented for two different taper profiles: exponential and triangular distributions. It is concluded that the optimization of the profile will provide the least pulse distortion     

Investigation of tapered multiple microstrip lines for VLSIcircuits

The analysis of tapered, coupled microstrip transmission lines is presented. These lines, used as interconnects between integrated circuit devices, are modeled using an iteration-perturbation approach applied in the spatial domain. From this model, a frequency-dependent scattering parameter characterization is determined. A time-domain simulation of pulse propagation through the tapered, coupled microstrip lines is performed. The frequency-domain scattering parameters are inverse Fourier transformed to obtain the time-domain Green's function. The input pulse is convolved with the Green's function, and a Newton-Raphson algorithm is applied to account for nonlinear loads. Some experimental results are shown, and a simulation approximation is proposed     

The Reflection Definition of the Characteristic Impedance of Microstrips

The frequency-dependent characteristic impedance shielded microstrips is computed by the scattering matrix of the step of rectangular transmission line to the shielded microstrip including higher order hybrid modes. This method avoids the ambiguities of the hitherto known definitions based on TEM quantities. For the dispersion characteristics a resonant model is used which reduces the number of the characteristic equations required. Numerical results are given including strips of finite thickness placed unsymmetrically in the shielded microstrip.     

Narrow-band microstrip bandpass filters with low radiation lossesfor millimeter-wave applications

Microstrip lines are attractive for the lower millimeter-wave ranges, but use of relatively thick substrates would be desirable in order to minimize losses. On such substrates the usual types of microstrip narrowband bandpass filters (formed from, e.g. coupled line segments with open ends) tend to radiate strongly giving very poor performance. It has been found that a grating technique initially developed for use with dielectric waveguides can be adapted for microstrips to obtain narrowband millimeter-wave microstrip filters with little radiation and strong filter characteristics. The stopbands are broad, the second passband occurring at three times the frequency of the first passband. These filters use parallel-coupled gratings with a single grating in cascade at each end. The modifications to the dielectric waveguide filter theory that are necessary for use with microstrips are detailed. Experimental results from microstrip realizations, which demonstrate their potential for millimeter-wave microstrip applications, are also presented     

A new development of an equivalent circuit model for magnetostaticforward volume wave transducers

A three-port equivalent circuit model of microstrip transducers used for the generation and detection of magnetostatic forward volume waves (MSFVW) is derived from fundamental physical considerations. In this circuit model, each microstrip MSFVW transducer is modeled as a three-port circuit incorporating a frequency-dependent series reactance, a frequency-dependent lossless transformer, and a lossy transmission line. Circuit parameters are determined in closed form by the use of solutions of pertinent boundary-value problems. The effects of parasitics, for example, capacities of bonding pads, are easily taken into account. Some typical transducer configurations are analyzed numerically. The three-port model developed is in excellent agreement with experiments. The model can be applied directly to nonuniform arrays of microstrips weighted by varying the separation between strip centers and the widths of successive strips or reversing the current direction of some groups of strips     

Dynamic Three-Dimensional TLM Analysis of Microstriplines on Anisotropic Substrate

The frequency-dependent propagation characteristics of a hybrid mode along microstriplines on anisotropic substrates are presented for the case where the constitutive parameter tensors maybe diagonalized. A generalization of the three-dimensional transmission-line-matrix (TLM) numerical procedure is used to obtain results for the phase constant Beta, effective permittivity epsilon/sub eff/, and the characteristic impedance Z, all as functions of frequency and the shape ratio (w/h). Also shown are results for coupled microstrips on a sapphire substrate.     

Accurate quasi-TEM spectral domain analysis of single and multiplecoupled microstrip lines of arbitrary metallization thickness

The quasi-TEM spectral domain approach (SDA) is extended to rigorously and efficiently analyze single and multiple coupled microstrip lines of arbitrary metallization thickness. The charge distributions on both the horizontal and vertical conductor surfaces are modeled by global basis functions. This results in a relatively small matrix for accurate determination of the line parameters of coupled thick microstrips. A convergence study is performed for the results of a pair of coupled lines with crucial structural parameters to explore the conditions for obtaining reliable solutions using the technique. Results for thick microstrips are validated through comparison with those from available measurements and another theoretical technique. The soundness of the technique is further demonstrated by looking into the trend of the results obtained by a simplified model in which the structural parameters are pushed, step by step, to the numerical extremities. Variations of circuit parameters of a four-line coupled microstrip structure due to the change of finite metallization thickness are presented and discussed     

The Design Parameters of Nonsymmetrical Coupled Microstrips (Comments)

A recent paper dealt with the subject of the design parameters of nonsymmetrical coupled microstrips for applications as microwave circuit elements. In this brief correspondence, the completeness and consistency of some of the results presented in the paper are examined and the existence of an earlier relatively comprehensive work reported on the same subject is pointed out.     

Insertion loss of magnetostatic-surface wave transducers $transmission-line model and experiment

In this paper, a transmission-line model is developed for the computation of the insertion loss of magnetostatic-surface wave transducers and measurements are carried out by the authors to check this model. In a first step of the analysis, closed-form expressions for the solution of the telegrapher's equations for the two microstrip transducers are obtained. The insertion loss is then derived from this solution as a function of three transmission-line parameters, i.e., the propagation constant and the characteristic impedance of the YIG-loaded microstrip line and the mutual inductance between the two microstrips, these quantities being, in general, complex. In a second step, these transmission-line parameters are numerically computed by applying a full-wave method-of-moments technique. Thus, the theoretical results obtained are found to be in good agreement with experimental results.     

Interdigital Microstrip Circuit Parameters Using Empirical Formulas and Simplified Model

Empirical formulas are given for single- and multiple-coupled microstrips, directly giving propagation mode admittances and phase velocities to be used in simplified expressions for the admittance parameters for the 2N-port network in the form of N-coupled strips, thus forming the basis for both analysis and synthesis of interdigital microstrip circuits. Calculated and measured results are presented for two interdigital band-pass filters synthesized as Chebyshev filters.     

衬底材料对微带线间串扰耦合的影响研究

随着系统频率的提高,衬底材料特性已成为影响信号走线之间串扰的一个不可忽略的因素。该文基于传输线方程和频域S参数对两平行微带线间串扰耦合进行理论分析,并结合全波3维电磁场仿真工具对具有不同介电常数和不同厚度的衬底材料进行了仿真和分析,得到了微带线在不同衬底下的电场分布,以及近端和远端串扰随频率、衬底介电常数和厚度变化的曲线。随着频率的增大,远端串扰将大于近端串扰,并且随着衬底介电常数和厚度的增加,微带线间的串扰呈现正弦上升的变化趋势。     

A New Microstrip Dispersion Model (Short Papers)

A new unified analysis technique is presented for dispersion in microstrip at high frequencies. The technique exploits the fact that the dispersion in microstrips is due to coupling between a surface-wave mode and the LSE mode of an appropriate model of the microstrip. The analysis uses an effective dielectric constant (EDC) approach to evaluate the mode coupling in the LSE model. Unlike previously reported models, all the parameters of the model are exactly determined from the quasistatic parameters of the microstrip, which takes the fringing field into account. Approximate closed-form equations are derived for the prediction of microstrip dispersion. The results agree within 1.50 percent with the experimental and previously published data over a wide useful range of microstrip dimensions and substrate permittivities.     

A termination scheme for high-speed pulse propagation on a systemof tightly coupled coplanar strips

A realistic termination scheme is proposed for closely coupled N-conductor microstrips. The design aims to achieve satisfactorily low signal reflection and good fabrication feasibility for the planar MMIC (Monolithic Microwave Integrated Circuit) process. The matched termination network (MTN) for a lossless three-line coupled microstrip structure is presented. High-speed pulse transmission along terminated tightly coupled microstrip lines is analyzed using modal analysis in the frequency domain. Theoretical results for the propagating and reflected waveforms are obtained by applying the inverse discrete Fourier transform (IDFT) to the system responses. These responses are obtained by applying the theory of multiconductor transmission lines to a dispersive database which has been computed using the spectral-domain approach (SDA). The response of a six-line closely coupled microstrip circuit terminated by the proposed termination scheme is measured using the HP8510B network analyzer. The measured results show that the reflected signal is below -30 dB and the results are in good agreement with the theoretical waveforms     

Spectral-domain computation of characteristic impedances andmultiport parameters of multiple coupled microstrip lines

A numerical procedure based on the spectral-domain techniques is formulated to compute all the frequency-dependent normal-mode parameters of general multiple coupled line structures in an inhomogeneous medium. In addition to the phase and attenuation constants for all the normal modes, these parameters include the line-mode and decoupled line modal impedances and the current and equivalent voltage eigenvector matrices of the coupled system. The multiport admittance (and impedance) matrices and coupled line equivalent-circuit model parameters are evaluated in terms of these normal-mode parameters. Numerical results for these normal-mode parameters for typical asymmetric two-, three-, and four-line microstrip structures are included to demonstrate the procedure and the frequency dependence of these parameters     

Simulation des régimes transitoires sur des sections de lignes microruban par une technique de filtrage numérique

This paper deals with a method for analysis of pulse transmission and reflection on microstrips sections that can be used as interconnection lines in or between high-speed digital integral circuits. It is shown that z-transform, which defines an intermediate domain between time and frequency, leads to a very general simulation method of the transient properties of the line sections. The line characteristics can be frequency dependent because of the propagation losses. The validity of the model is established from direct measurements on microstrip sections etched on alumina and GaAs substrates.     

High-frequency, transient response of microstrip lines

Two expressions for the impulse response function of resistive microstrip transmission lines, including the effects of frequency-dependent field penetration (classical skin effect), are derived. One expression is complete in the sense that the three parameters on which it depends are expressed in terms of the material and geometrical properties of the stripline. The other expression is unexpectedly simple in form and depends on only two parameters, propagation delay and effective response time. At present, these parameters must be determined by matching the response predicted by both expressions to representative pulses. These then agree to ±1% with each other and with recent transient experimental results of J.S. Loos and A.H. Endvik. These expressions should find application in the design and simulation of multi-gigabit-per-second, digital pulse transmission over microstrip lines     

A Frequency-Dependent Coupled-Mode Analysis of Multiconductor Microstrip Lines with Application to VLSI Interconnection Problems

The spectral Galerkin procedure is used to calculate the dispersion properties of multiple conductor microstrip lines. The resulting propagation constants are then used in a coupled-mode theory which demonstrates a frequency-dependent coupling of current in a five-conductor system. These results should he useful in the study of crosstalk between parallel microstrip lines used in VLSI interconnections.     

Accurate Wide-Range Design Equations for the Frequency-Dependent Characteristic of Parallel Coupled Microstrip Lines

In this paper, closed-form expressions are presented which model the frequency-dependent even- and odd-mode characteristics of parallel coupled microstrip lines with hitherto unattained accuracy and range of validity. They include the effective dielectric constants, the characteristic impedances using the power-current formulation, as well as the open-end equivalent lengths for the two fundamental modes on coupled microstrip. The formulas are accurate into the millimeter-wave region. They are based on an extensive set of accurate numerical data which were generated by a rigorous spectral-domain hybrid-mode approach and are believed to represent a substantial improvement compared to the state-of-the-art and with respect to the computer-aided design of coupled microstrip filters, directional couplers, and related components.