Finite-length Lines Research Articles

Coupling Analysis of Complex-Layout Traces Using a Circuit-Concept Approach

An analytical method is studied for estimating coupling between arbitrarily directed multiple finite-length lines with different line lengths and heights. Coupling or crosstalk analysis is performed by developing an expanded circuit-concept approach based on modified telegrapher's equations of the Agrawal approach instead of the Taylor approach, providing some computational advantages. An electric image method using the quasi-static terms of the accurate Green's function is used to estimate the electromagnetic fields in an inhomogeneous medium such as a printed circuit board. The approach is applied to the analysis of parallel and nonparallel or bent microstrip models, and embedded-line models in which one line is embedded and the other is on the surface layer. To verify the proposed approach, we conducted some experiments and compared the results of our approach with the results of measurements and a commercial electromagnetic solver.

Analytical Solution for Voltage-Step Response of Lossy Distributed RC Lines

This paper presents an analytical solution for the voltage-step response of finite-length open-ended distributed lossy RC lines. Three line configurations with differently arranged distributed transversal conductivities causing charge loss are considered. Telegrapher's equation for voltage is solved at three different initial/boundary conditions using the method of Fourier series.

Backward Wave Microstrip Lines With Complementary Spiral Resonators

Microstrip lines loaded with series gap discontinuities and compact metamaterial particles-complementary Archimedean spiral resonators-are investigated. The theory of periodic structures is applied for establishing the propagation characteristics of infinite lines from full-wave electromagnetic simulations. Thanks to their convoluted geometry, the spirals are very compact which makes the unit cell electrically small (e.g., 0.1 guided wavelength or even smaller). Then, the effective medium theory is applied to extract the effective permittivity and permeability of the periodic structure. By analyzing the effective medium parameters and phase constant, it is shown that the structure supports backward wave propagation and exhibits double negative parameters over a 19% bandwidth around its zero-reflection frequency. Moreover, a simple equivalent-circuit model of the unit cell is established. Finally, finite-length lines with one or two complementary spirals are investigated. It is shown by comparison with full-wave results that the circuit model almost perfectly describes the structure for all practically important frequencies. It is also shown that the inter-element coupling is negligible in the multi-spiral structures considered. Measured results for two prototypes are presented to verify the analyses.

Generalized Form of Telegrapher's Equations for the Electromagnetic Field Coupling to Finite-Length Lines Above a Lossy Ground

In this paper, a generalized form of the Telegrapher's equations for electromagnetic field coupling to finite-length transmission lines above a lossy ground is derived. The approach is fully based on the thin-wire antenna theory. The effect of a lossy half-space is taken into account by means of the reflection coefficient approximation. The conductor losses can also be taken into account via surface impedance per unit length. The resulting equations are handled numerically via the Galerkin--Bubnov indirect boundary element method. Numerical results are presented for induced current along the line, and compared with transmission line (TL) approximation, for the case of lossless conductor. It is shown that the TL approximation can result in a significant underestimation of the induced currents.

Analysis of Crosstalk between Finite-Length Multiconductor Transmission Lines on a PCB by Using Circuit-Concept Approach

In this paper, crosstalk between multiconductor transmission lines of finite length in arbitrary directions on a printed circuit board is studied by using a circuit-concept approach. The circuit-concept approach of (2+1) finite-length lines is expanded for the crosstalk calculation of (n + 1) lines where n > 2. 2n-port network expression is derived from the modified telegrapher equations. The effect of via currents flowing through the vertical short line sections at the line terminals is also investigated. Due to this expansion the derived equations for (n + 1) lines are expected to be easily applied for crosstalk analysis of a variety of complex structures such as via fences and guard traces, etc.

Diffraction of Electromagnetic Waves by an Antenna Array with Coaxial Openings

We obtain an exact solution to the problem of diffraction of a plane electromagnetic wave by an antenna array consisting of a metal screen with openings in the form of finite-length coaxial lines. The dependence of the absolute value of the transmission and reflection coefficients on the array parameters is studied.

Crosstalk analysis between finite-length microstrip lines in neighborhood

Crosstalk analysis between finite-length microstrip lines in neighborhood

Electromagnetic interference from carrier channels on finite-length power lines above a lossy ground in a wide frequency range

Prediction models of the electromagnetic interference generated by carrier channels on multiconductor power distribution lines with nonradiating terminal loads are presented. The proposed formulations are addressed to the evaluation of the radiated field components in a wide frequency-range, by including the effects of the lossy ground plane and removing the hypothesis of unidirectional current propagation. The validity of the infinite-length approximation and of the complex image approach are investigated, with reference to different line-configuration, in case of wire-to-ground and wire-to-wire signal transmission.

Time-domain analysis of electromagnetic interference from broadband digital signal transmission on finite-length power networks

A new procedure is presented for the prediction of the electromagnetic interference produced by digital signal transmission on power line carrier channels. The network radiation model is based on the rigorous formulation of the field components produced by bi-directional current propagation along finite-length overhead lines, and is particularly suitable for the analysis of the field distribution in proximity of the ports of the network, where sensitive electrical and electronic devices are generally located. The procedure is applied to the analysis of digital signal carrier channels on tree- or loop-type power distribution networks, in order to assess the influence of the load configuration, distance from the radiation source and coupling arrangement, on the electromagnetic pollution level.

隣接する有限長マイクロストリップ線路間のクロストーク解析

隣接する有限長マイクロストリップ線路間のクロストーク解析

Visibility of New Dashed Yellow and White Center Stripes as Function of Material Retroreflectivity

Economic and environmental concerns have raised questions about the continued use of yellow center lines on two-lane highways and yellow left-edge lines on divided highways or freeway entrance and exit ramps. The use of yellow pavement markings as a warning to indicate opposing traffic appears to be a concept that is compatible with certain human factors population stereotypes and accepted industry standards (yellow for caution), but it is unclear how well the general driver population understands the message conveyed by yellow pavement markings. Another question is how the visibility of yellow center lines or left-edge lines compares with the visibility of similar white pavement markings. The effects of color (white and yellow) and material retroreflectivity (low, medium, and high) on the end detection distance of finite-length center lines at night under automobile low-beam illumination were determined. Ten subjects were used in a field experiment (rural, automobile low-beam conditions) to obtain the end detection distances of finite-length center stripes of 0.1-m width. The data show that the end detection distances of new yellow dashed center stripes and new white dashed center stripes are about the same. The average end detection distance was 30 to 35 m for the low-retroreflectivity material and about 62 m for the high-retroreflectivity material (four- to fivefold retroreflectivity increase). It is tentatively concluded that the use of white center stripes most likely will not result in a significant increase in the end detection distance when compared with the use of similar yellow center stripes. It is also tentatively concluded that an increase in the retroreflectivity of the pavement marking materials will result in a significant and desirable increase of the visibility distance, but to provide a minimum preview time of 3.6 sec (at a vehicle speed of 90 km/hr), even higher-retroreflectivity materials than the ones used in this study will be required.

Visibility of New Dashed Yellow and White Center Stripes as Function of Material Retroreflectivity

Economic and environmental concerns have raised questions about the continued use of yellow center lines on two-lane highways and yellow left-edge lines on divided highways or freeway entrance and exit ramps. The use of yellow pavement markings as a warning to indicate opposing traffic appears to be a concept that is compatible with certain human factors population stereotypes and accepted industry standards (yellow for caution), but it is unclear how well the general driver population understands the message conveyed by yellow pavement markings. Another question is how the visibility of yellow center lines or left-edge lines compares with the visibility of similar white pavement markings. The effects of color (white and yellow) and material retroreflectivity (low, medium, and high) on the end detection distance of finite-length center lines at night under automobile low-beam illumination were determined. Ten subjects were used in a field experiment (rural, automobile low-beam conditions) to obtain the end detection distances of finite-length center stripes of 0.1-m width. The data show that the end detection distances of new yellow dashed center stripes and new white dashed center stripes are about the same. The average end detection distance was 30 to 35 m for the low-retroreflectivity material and about 62 m for the high-retroreflectivity material (four- to fivefold retroreflectivity increase). It is tentatively concluded that the use of white center stripes most likely will not result in a significant increase in the end detection distance when compared with the use of similar yellow center stripes. It is also tentatively concluded that an increase in the retroreflectivity of the pavement marking materials will result in a significant and desirable increase of the visibility distance, but to provide a minimum preview time of 3.6 sec (at a vehicle speed of 90 km/hr), even higher-retroreflectivity materials than the ones used in this study will be required.

Analysis of radiation characteristics of a finite-length transmission line using a circuit-concept approach

The radiation phenomenon from a transmission line of finite length is described. Based on the hypothesis of reciprocity between the coupling of an external wave to a transmission line and the radiation from a transmission line, a set of models for both phenomena is implemented using a six-terminal network. The goal is to find out what current is induced in each terminal load of the network. The radiation characteristics of finite-length lines such as radiation fields, radiation power-density, and radiation coefficients are considered. Experiments using both straight lines and bent lines have been performed to validate the theory.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Synthesis of nonuniform transmission lines with terminal discontinuities

An integral equation was previously derived by the authors (ibid., vol.AP-34, p.546-53, Apr. 1986) for the inverse problem associated with finite-length nonuniform lines having known impedance discontinuities at the input and output. A procedure for determining the characteristic impedance profile of the line from the solution of the integral equation was also presented. Here, the numerical aspects of this inverse problem are treated. This equation is solved using general expansions of both the kernel and unknown functions, thereby reducing the integral equation to a system of linear algebraic equations. This makes possible a numerical implementation of the theory by which the impedance profile of a nonuniform line may be reconstructed from given spectral data. The realizability aspects of the problem are treated and several examples of computer-assisted profile inversion are presented. >

Coupling Model of Crossing Transmission Lines

The coupling between transmission lines crossing diagonally is described. The resulting equations are derived by neglecting the recoupling of the line under induction (acceptor line (AL)) to the exciter line (EL). The coupling coefficients of various models are also considered. Equivalent-circuit representations for finite-length lines are obtained in two different forms: one expressed in terms of ideal voltage and ideal current sources, and the other in terms of ideal transformers, mutual inductance, and mutual capacitance. The first expressions are useful for predicting coupling between various types of lines. The second shows the coupling mechanism. The validity of the theory is confirmed by the experimental studies.