Wave Propagation on Nonuniform Lines

Menemenlis,; Chun, Chun

doi:10.1109/mper.1982.5519407

Cited by 9 publications

(21 citation statements)

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“…Now we will consider a nonuniform transmission line approximation (e.g., Wagner and Hileman [25]; Menemenlis and Chun [26]) and show that it is consistent with our scattering theory analysis given in Sections II-IV. In this approximation, the apparent attenuation of current with height can be attributed to waves reflected back to the source.…”

Section: Nonuniform Transmission-line Approximationsupporting

confidence: 65%

On the Mechanism of Attenuation of Current Waves Propagating Along a Vertical Perfectly Conducting Wire Above Ground: Application to Lightning

Baba

Rakov

2005

IEEE Trans. Electromagn. Compat.

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Abstract-It is known from both theory and numerical simulations that a current pulse suffers apparent attenuation as it propagates along a vertical perfect conductor of uniform, nonzero thickness (e.g., a cylinder) above perfectly conducting ground, excited at its bottom by a lumped source. The associated electromagnetic field structure is non-transverse electromagnetic (TEM), particularly near the source region. On the other hand, it has been shown analytically by Thottappillil et al. (2001Thottappillil et al. ( , 2004 that no attenuation occurs and the electromagnetic field structure is pure transverse electromagnetic (TEM) if the conductor thickness and source size are assumed to be infinitesimal. The goal of this paper is to examine the mechanism of current attenuation as it propagates along a nonzero thickness conductor, based on the scattering theory and on a nonuniform transmission line approximation. In applying the scattering theory, we decompose the "total" current in the conductor into two components that we refer to as the "incident" and "scattered" currents. The "incident" current serves as a reference (no attenuation), specified disregarding the interaction of resultant electric and magnetic fields with the conductor, while the "scattered" current, found here using the finite-difference time-domain (FDTD) method, can be viewed as a correction to account for that interaction. The scattered current modifies the incident current so that the resultant total current pulse appears attenuated. Thus, the current attenuation is likely to be due to field scattering that does not occur in the case of zero thickness conductor. The attenuation of the total current pulse is accompanied by the lengthening of its tail, such that the total charge transfer is independent of height. Approximation of the vertical conductor above ground by a nonuniform transmission line whose characteristic impedance increases with increasing height is shown to reasonably reproduce the current pulse attenuation predicted by the scattering theory. In this approximation, the apparent current attenuation with height can be attributed to waves reflected back to the source. The results have important implications for development and interpretation of lightning models.

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Section: Nonuniform Transmission-line Approximationsupporting

confidence: 65%

On the Mechanism of Attenuation of Current Waves Propagating Along a Vertical Perfectly Conducting Wire Above Ground: Application to Lightning

Baba

Rakov

2005

IEEE Trans. Electromagn. Compat.

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“…6, examined in this example is the one introduced in [1]. The structure is used to represent a tower.…”

Section: B Vertical Structurementioning

confidence: 99%

“…It has a circular cross-section with radius of 0.7 m. In our study, we use the equations given in [13] to calculate the characteristic impedance. The selected radius results in a value for the characteristic impedance at the top of the tower equal to that obtained from used in [1], [2], [5]. The ground resistivity is assumed to be 30 -m.…”

Section: B Vertical Structurementioning

confidence: 99%

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Modeling Nonuniform Transmission Lines for Time Domain Simulation of Electromagnetic Transients

Ramirez

Semlyen

Iravani

2002

IEEE Power Eng. Rev.

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“…It is worth noting that in all of the above time-domain definitions, the resulting impedance is not only dependent upon the tower's geometry and electrical parameters, but also on the injected current pulse [17].…”

Section: Introductionmentioning

confidence: 99%

On Tower Impedances for Transient Analysis

Grcev

Rachidi

2004

IEEE Trans. Power Delivery

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Abstract-The analysis of the dynamic behavior of power transmission line and telecommunication towers is of interest in protection and EMC studies related to lightning. Usually, time-domain surge impedance is used to characterize tower dynamic behavior. The main drawback in the definition of such surge impedance is that it is dependent on the excitation waveshape and there is no consensus on the current waveshape to be used. Also, there is no consensus on the unique definition of the involved voltage. This paper explores possibilities for a systematized approach to the analysis and uniquely defined quantities that characterize transient response of towers. Further, limitations associated with simplified approaches are emphasized by examining examples of direct comparison between computations based on transmission-line approach and antenna theory for a 100-m tall tower. It is pointed out that problems in the definition of voltages might occur above 100 kHz, especially near resonant frequencies, while differences in current distribution exist already at the lowest frequencies.

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Wave Propagation on Nonuniform Lines

Cited by 9 publications

References 0 publications

On the Mechanism of Attenuation of Current Waves Propagating Along a Vertical Perfectly Conducting Wire Above Ground: Application to Lightning

On the Mechanism of Attenuation of Current Waves Propagating Along a Vertical Perfectly Conducting Wire Above Ground: Application to Lightning

Modeling Nonuniform Transmission Lines for Time Domain Simulation of Electromagnetic Transients

On Tower Impedances for Transient Analysis

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