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  • 51.
    Månssson, Daniel
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Ericsson, J.
    Thottappillil, Rajeev
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Effect of conducted EFT type pulses on the point of entry of electrical systems in buildings2005In: Radio Vetenskap och Kommunikation (RVK05), Linköping, June 14-16, 2005, p. 5 sid-Conference paper (Refereed)
  • 52. Nag, Amitabh
    et al.
    Rakov, Vladimir A.
    Schulz, Wolfgang
    Saba, Marcelo M. F.
    Thottappillil, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Biagi, Christopher J.
    Oliveira Filho, Alcides
    Kafri, Ahmad
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Theethayi, Nelson
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Götschl, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    First versus subsequent return-stroke current and field peaks in negative cloud-to-ground lightning discharges2008In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 113, no D19, p. D19112-Article in journal (Refereed)
    Abstract [en]

    We examine relative magnitudes of electric field peaks of first and subsequent return strokes in negative cloud-to-ground lightning flashes recorded in Florida, Austria, Brazil, and Sweden. On average, the electric field peak of the first stroke is appreciably, 1.7 to 2.4 times, larger than the field peak of the subsequent stroke ( except for studies in Austria where the ratio varies from 1.0 to 2.3, depending on methodology and instrumentation). Similar results were previously reported from electric field studies in Florida, Sweden, and Sri Lanka. For comparison, directly measured peak currents for first strokes are, on average, a factor of 2.3 to 2.5 larger than those for subsequent strokes. There are some discrepancies between first versus subsequent stroke intensities reported from different studies based on data reported by lightning locating systems (LLS). The ratio of LLS-reported peak currents for first and subsequent strokes confirmed by video records is 1.7 to 2.1 in Brazil, while in the United States ( Arizona, Texas, Oklahoma, and the Great Plains) it varies from 1.1 to 1.6, depending on methodology used. The smaller ratios derived from the LLS studies are likely to be due to poor detection of relatively small subsequent strokes. The smaller values in Austria are possibly related ( at least in part) to the higher percentage ( about 50% versus 24-38% in other studies) of flashes with at least one subsequent stroke greater than the first. The effects of excluding single-stroke flashes or subsequent strokes in newly formed channels appear to be relatively small.

  • 53. Pavanello, Davide
    et al.
    Rachidi, Farhad
    Rubinstein, Marcos
    Theethayi, Nelson
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Thottappillil, Rajeev
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Electromagnetic environment in the immediate vicinity of a tower struck by lightning2004In: Euro Electromagnetics (EUROEM), Magdeburg, Germany, 2004Conference paper (Other scientific)
  • 54. Raysaha, Rosy
    et al.
    Kumar, Udaya
    Cooray, Vernon
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Thottappillil, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Special case of lightning strike to tall objects on ground2010In: 30TH International Conference on Lightning Protection, ICLP, Cagliary, Italy, 2010Conference paper (Refereed)
  • 55. Rubinstein, M
    et al.
    Thottappillil, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Rachidi, Farhad
    Discussion on the influence of the time derivative of the current and the charge acceleration on the radiation fields from lightning channels2007Conference paper (Other academic)
  • 56. Schulz, Wolfgang
    et al.
    Sindelar, S
    Kafri, Ahmad
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Götschl, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Theethayi, Nelson
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Thottappillil, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    The Ratio Between First And Subsequent Lightning Return Stroke Electric Field Peaks In Sweden2008Conference paper (Refereed)
  • 57.
    Theethayi, Nelson
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Baba, Yoshihiro
    Rachidi, Farhad
    Thottappillil, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    On the choice between transmission line equations and full-wave Maxwell's equations for transient analysis of buried wires2008In: IEEE transactions on electromagnetic compatibility (Print), ISSN 0018-9375, E-ISSN 1558-187X, Vol. 50, no 2, p. 347-357Article in journal (Refereed)
    Abstract [en]

    In this paper, we evaluate the validity of transmission line (TL) solutions in the study of interaction of lightning transients with buried wires. The considered transients have frequencies between a few kilohertz to a few megahertz with risetimes 0.1-10 s. Comparative simulations using TL equations and full-wave Maxwell's equations are carried out in the paper, and the solutions to both the equations are based on the finite-difference time-domain method. It is found that TL solutions are sufficiently accurate for lightning transient analysis of buried wires. It is also claimed that the TL approach remains valid for all transients having frequencies lower than those of lightning. TL solutions are computationally efficient, particularly when dealing with distributed power and railway systems. The TL approach is valid as long as the transverse electromagnetic mode (TEM) is dominant. However, other modes of propagation, classified as antenna modes, might be present depending upon the type of excitation source, its location, frequency, and the associated media. A possible approximate formula for the frequency above which the validity of TL solutions for buried systems is questionable is proposed based on the concept of penetration depth of fields into the soil. Discussions presented in the paper could motivate the application of TL solutions for electromagnetic transient analyses of the buried conductors of power, railway, and telecommunication systems. 

  • 58.
    Theethayi, Nelson
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Diendorfer, Gerhard
    Thottappillil, Rajeev
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    On Determining the Effective Height of Gaisberg Tower2004In: Euro Electromagnetics (EUROEM), Magdeburg, Germany, 2004Conference paper (Other scientific)
  • 59.
    Theethayi, Nelson
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Liu, Yaqing
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Montano, Raul
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Thottappillil, Rajeev
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Zitnik, Mihael
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Cooray, Vernon
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Scuka, Viktor
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    A theoretical study on the consequence of a direct lightning strike to electrified railway system in Sweden2005In: Electric Power System Research, Vol. 74, p. 267-280Article in journal (Refereed)
    Abstract [en]

    Direct lightning strike to a single-track electrified railway system in Sweden is modeled in this paper. Using this model, the induced voltages in each of the nine conductors at heights varying from 0.5 m (tracks) to 10 m above the ground are estimated. The effect of the finitely conducting ground is included using a time domain expression for the transient ground impedance that has better early time and late time behavior. The main interconnection between the conductors and the flashover strength of the supporting insulators is included in the simulations. A simple model for the arc channel during flashover of the insulators and the ionization of the soil around the pole foundations is also included in the model to assess the possible realistic surge voltage distribution in the system. It is shown in the paper that finite ground conductivity, interconnections between the conductors, arcing phenomena of insulation flashover and grounding of the poles decide the voltage/current distribution in the conductors. Simulations have been also carried out to determine the voltages on the lines and across the rails as function of distance from the point of strike as it could be a necessary data for deciding the possible future protection schemes. It was found that for a lightning stroke of 31 kA peak, large common mode and differential mode surges exist on the lines which could create excessive voltages between the line and neutral of the transformer and might pose a threat to the various low voltage equipments used for telecommunication, signaling and control.

  • 60.
    Theethayi, Nelson
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Division for Electricity and Lightning Research.
    Mazloom, Ziya
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Division for Electricity and Lightning Research.
    Thottappillil, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Division for Electricity and Lightning Research.
    Technique for Reducing Transient Voltages in Multiconductor-Shielded Cables2007In: IEEE transactions on electromagnetic compatibility (Print), ISSN 0018-9375, E-ISSN 1558-187X, Vol. 49, no 2, p. 434-440Article in journal (Refereed)
    Abstract [en]

    It is a common practice that the unused pairs (inactive conductors) in shielded cables are left open (open circuited at the terminal block) in telecommunication systems. In this paper, it is shown by both theory (based on transmission line analysis) and experiments that if those inactive conductors are shorted to the cable shield, then the transient voltages on the other active conductors (conductors in service) can be reduced when external transients/faults due to lightning or switching couple to the shield. This could be a good EMC practice for transient voltage reduction in telecommunication systems.

  • 61.
    Theethayi, Nelson
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Mazloom, Ziya
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Thottappillil, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Lindeberg, P. A
    Schütte, Thorsten
    Review of Research on Lightning Interaction with the Swedish Railway Network2008Conference paper (Other academic)
  • 62.
    Theethayi, Nelson
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Mazloom, Ziya
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Thottappillil, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Lindeberg, Per-Anders
    Schutte, Thorsten
    Lightning Interaction with the Swedish Railway Network2007Conference paper (Refereed)
  • 63.
    Theethayi, Nelson
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Rakov, Vladimir A.
    Thottappillil, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Responses of airport runway lighting system to direct lightning strikes: Comparisons of TLM predictions with experimental data2008In: IEEE transactions on electromagnetic compatibility (Print), ISSN 0018-9375, E-ISSN 1558-187X, Vol. 50, no 3, p. 660-668Article in journal (Refereed)
    Abstract [en]

    A test airport runway lighting system, including a buried cable protected by a counterpoise and vertical ground rods, was subjected to direct lightning strikes, and currents and voltages measured in different parts of the system were reported earlier by Bejleri et al. In this paper, we attempt to model the lightning interaction with this system using the transmission line theory. Lumped devices along the cable such as current regulator and transformers are ignored, possible nonlinear phenomena (arcing) in the system are neglected, the soil is assumed to be homogeneous. The model-predicted currents in the counterpoise, ground rod, and the cable are compared with the measurements, and a reasonable agreement was found for the currents along the counterpoise. It is found that current in the counterpoise is not much influenced by the presence of the cable. Further, vertical ground rods connected to the counterpoise do not have significant influence on the current distribution along the counterpoise. It appears that the model is unable to predict cable currents and voltages in the test system, presumably due to neglecting nonlinear phenomena in the soil and in cable's insulation and electromagnetic coupling with the lightning channel.

  • 64.
    Theethayi, Nelson
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. elektricitetslära och åskforskning.
    Thottappillil, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. elektricitetslära och åskforskning.
    Lightning Interaction with Electrified Railways, in Tutorial on EMC aspects of Lightning2006Conference paper (Other academic)
  • 65.
    Theethayi, Nelson
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Thottappillil, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Lightning Interaction with Electrified Railways, in Tutorial on EMC aspects of Lightning2007Conference paper (Refereed)
  • 66.
    Theethayi, Nelson
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. elektricitetslära och åskforskning.
    Thottappillil, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. elektricitetslära och åskforskning.
    On reducing the internal voltages and currents due to lightning transients in buried shielded cables2006In: Proceedings of the 28th Internat Conference on Lightning Protection, Kanazawa, Japan, 2006, p. 1322-1327Conference paper (Refereed)
  • 67.
    Theethayi, Nelson
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Thottappillil, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    On Reducing the Lightning Transients in Buried Shielded Cables Using Follow-On Earth Wire2007In: IEEE transactions on electromagnetic compatibility (Print), ISSN 0018-9375, E-ISSN 1558-187X, Vol. 49, no 4, p. 924-927Article in journal (Refereed)
    Abstract [en]

    This paper investigates the importance of a follow-on buried bare earth wire for the lightning protection of buried shielded cables. The use of follow-on bare wires for lightning protection of communication towers was suggested as a recommendation in certain standards, without being complemented either by theory or experiments. When lightning transients couple to the cable shields, it induces large currents (depending on the type of coupling) causing transient overvoltages between the inner conductors and the shield. It is shown by simulations based on multiconductor transmission line theory that if the follow-on bare earth conductor is placed in parallel with the shielded cable with the bare earth wire connected to the shield at the current injection end, then the shield current, and thereby, the internal transient voltages of the cable are reduced considerably.

  • 68.
    Theethayi, Nelson
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. elektricitetslära och åskforskning.
    Thottappillil, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. elektricitetslära och åskforskning.
    Simple Expressions for External Wire Impedance and Admittance for Lightning Current Pulse Propagation in Buried Wires2006Conference paper (Refereed)
  • 69.
    Theethayi, Nelson
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Thottappillil, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Some Issues Concerning Lightning Strikes to Communication towers2007In: Journal of Electrostatics, ISSN 0304-3886, E-ISSN 1873-5738, Vol. 65, no 10-11, p. 689-703Article in journal (Refereed)
    Abstract [en]

    It is a usual phenomenon that lightning strikes tall communication towers. Some of the questions about lightning interaction with communication towers are dealt with in this paper. Can tall towers influence the incidence of lightning in the area where the tower is situated? Are the parameters of lightning, such as peak currents, influenced by the presence of the tower where lightning strikes? What would be the difference in the electric and magnetic field environment in the near vicinity of the tower and far from the tower when compared to the corresponding values with lightning striking level ground? Are lightning protection methods designed primarily to protect the communication equipment sufficient to prevent lightning surge transfer to nearby local networks? This paper addresses the above issues based on the analysis, models and observations made in the recent past and also using some simple calculations by the authors.

  • 70.
    Theethayi, Nelson
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Thottappillil, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Surge propagation and crosstalk in multiconductor transmission lines above ground, Chapter 22008In: Electromagnetic Field Interaction with Transmission Lines From Classical Theory to HF Radiation Effects / [ed] F. Rachidi and S. Tkachenko, WIT Press, UK , 2008Chapter in book (Other (popular science, discussion, etc.))
  • 71.
    Theethayi, Nelson
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Thottappillil, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Surge propagation in multiconductor transmission line below ground, Chapter 32008In: Electromagnetic Field Interaction with Transmission Lines From Classical Theory to HF Radiation Effects / [ed] F. Rachidi and S. Tkachenko, WIT Press, UK , 2008Chapter in book (Other (popular science, discussion, etc.))
  • 72.
    Theethayi, Nelson
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Thottappillil, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Diendorfer, Gerhard
    Mair, Martin
    Pichler, Hannes
    Currents in Buried Grounding Strips Connected to Communication Tower Legs during Lightning Strikes2008Conference paper (Other academic)
  • 73.
    Theethayi, Nelson
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Thottappillil, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Diendorfer, Gerhard
    Mair, Martin
    Pichler, Hannes
    Currents in Buried Grounding Strips Connected to Communication Tower Legs during Lightning Strikes2008Conference paper (Refereed)
  • 74.
    Theethayi, Nelson
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Thottappillil, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Diendorfer, Gerhard
    Mair, Martin
    Pichler, Hannes
    Currents in buried grounding strips connected to communication tower legs during lightning strikes2008In: IEEE transactions on dielectrics and electrical insulation, ISSN 1070-9878, E-ISSN 1558-4135, Vol. 15, no 4, p. 1153-1161Article in journal (Refereed)
    Abstract [en]

    During a lightning strike to communication tower stroke currents are shared by the tower and by the shields of the cables along the tower. The currents in the tower proceed towards the grounding system (possibly a combination of counterpoises or ring conductors or ground rods or grounding grids) connected to tower legs' foundation. In this paper, lightning strike to communication tower on mount Gaisberg in Austria is considered and measured currents at the tower top and those shared by an instrumented grounding strip connected to one of the tower leg's are presented. The measured currents at different locations on the 70-m long ground strip are compared with the predictions of a frequency dependant lossy transmission line (TL) model and reasonably good agreement was found. From this validation it is claimed that the TL models are appropriate for lightning transient analysis of grounding systems.

  • 75.
    Theethayi, Nelson
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Thottappillil, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Liu, Yaqing
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Montano, Raul
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Important Parameters That Influence Crosstalk in Multiconductor Transmission Lines2007In: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 77, no 8, p. 896-909Article in journal (Refereed)
    Abstract [en]

    Transient surges in one of the overhead conductors, due to direct lightning strikes, causes crosstalk [C.R. Paul, Analysis of Multiconductor Transmission Lines, John Wiley & Sons, Inc., 1994; C.R. Paul, Introduction to Electromagnetic Compatibility, John Wiley & Sons, Inc., 1992] in other adjacent conductors. It is a common electromagnetic interference (EMI) phenomenon observed in power lines, communication lines and electrified railway lines. In this paper we investigate the crosstalk in multiconductor transmission lines (MTLs) above finitely conducting ground as a function of ground conductivity, heights of the receptor conductor and the terminal loads. For receptor conductor close to the ground, compared to the emitter conductor [C.R. Paul, Analysis of Multiconductor Transmission Lines, John Wiley & Sons, Inc., 1994; C.R. Paul, Introduction to Electromagnetic Compatibility, John Wiley & Sons, Inc., 1992], the decrease in ground conductivity increases the crosstalk peak currents at near end (end near to the source in the emitter conductor) of the receptor conductor, but at the far end it could either increase or decrease depending upon the line height and ground conductivity.

    It is found that the ground impedance [J.R. Carson, Wave propagation in overhead wires with ground return, Bell. Sys. Tech. J. 5 (1926) 539–554; Y.J. Wang, S.J. Liu, A review of methods for calculation of frequency dependant impedance of overhead power transmission lines, Proc. Natl. Sci. Conc. ROC (A), 25 (6), (2001) 329–338; E.D. Sunde, Earth conduction effects in transmission systems, 1st ed., Dover Publications Inc., New York, 1968; A. Deri, G. Tevan, A. Semlyen, A. Castanheira, The complex ground return plane a simplified model for homogenous & multilayer earth return, IEEE Trans. PAS 100 (8) (1981) 3686–3693; K.C. Chen, K.M. Damrau, Accuracy of approximate transmission line formulas for overhead wires, IEEE Trans. EMC 31 (4) (1989) 396–397; A. Semlyen, Ground return parameters of transmission lines an asymptotic analysis for very high frequencies, IEEE Trans. PAS 100 (3) (1981) 1031–1038; E.F. Vance, Coupling to Cable Shields, Wiley Interscience, New York, 1978; J.R. Wait, Theory of wave propagation along a thin wire parallel to an interface, Radio Sci. 7 (6) (1972) 675–679; R.G. Olsen, J.L. Young, D.C. Chang, Electromagnetic wave propagation on a thin wire above earth, IEEE Trans. Anten. Propag. 48 (9) (2000) 1413–1418; M. D’Amore, M.S. Sarto, Simulation models of a dissipative transmission line above a lossy ground for a wide-frequency range. I. Single conductor configuration, IEEE Trans. EMC 38 (2) (1996) 127–138; M. D’Amore, M.S. Sarto, Simulation models of a dissipative transmission line above a lossy ground for a wide-frequency range. II. Multiconductor configuration, IEEE Trans. EMC 38 (2) (1996) 139–149; F. Rachidi, C.A. Nucci, M. Ianoz, C. Mazzetti, Influence of lossy ground on lightning induced voltages on overhead lines, IEEE Trans. EMC 38 (3) (1996) 250–264; F. Rachidi, C.A. Nucci, M. Ianoz, Transient analysis of multiconductor lines above a lossy ground, IEEE Trans. Power Deliv. 14 (1) (1999) 294–302; F.M. Tesche, M.V. Ianoz, T. Karlsson, EMC Analysis Methods and Computational Models, John Wiley and Sons Inc., 1997; A.K. Agrawal, H.J. Price, S.H. Gurbaxani, Transient response of multiconductor transmission lines excited by a nonuniform electromagnetic field, IEEE Trans. EMC 22 (2) (1980) 119–129] has profound influence in all the crosstalk cases studied here. Hence, a brief review and comparison of different closed form ground impedance expressions under the limits of transmission line approximation [F.M. Tesche, M.V. Ianoz, T. Karlsson, EMC Analysis Methods and Computational Models, John Wiley and Sons Inc., 1997] and its behavior at both high and low frequencies is presented. It is shown that low frequency approximation of ground impedance is not sufficient for lightning transient studies involving ground conductivities lower than 10 mS/m. The observations presented in the paper have important implications in EMI studies of large distributed outdoor systems, such as the railway network, subjected to lightning strikes.

  • 76.
    Theethayi, Nelson
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Thottappillil, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Paolone, Mario
    Department of Electrical Engineering University of Bologna.
    Nucci, Carlo Alberto
    Department of Electrical Engineering University of Bologna.
    Rachidi, Farhad
    Swiss Federal Institute of Technology.
    External Impdeance and Admittance of Buried Horizontal Wires for Transient Studies Using Transmission Line Analysis2007In: IEEE transactions on dielectrics and electrical insulation, ISSN 1070-9878, E-ISSN 1558-4135, Vol. 14, no 3, p. 751-761Article in journal (Refereed)
    Abstract [en]

    The paper investigates the applicability of some closed form expressions for the ground impedance and ground admittance of buried horizontal wires (bare and insulated) for lightning or switching transient analyses based on transmission line (TL) theory. In view of the frequency contents that typically characterize such transients, the behavior of the ground impedance and admittance is studied for a wide frequency range up to 10 MHz. Low frequency approximation of the ground impedance is not always appropriate for transient analysis. Sensitivity analyses show that, unlike overhead wires, the ground impedance for buried wires is little sensitive to the ground conductivity. On the other hand, the ground admittance varies strongly with the ground conductivity. The paper also discusses the results of transient analysis of buried cables performed by means of electromagnetic transient programs (EMTP) that neglect the ground admittance. The limits of such an approximation are discussed in order to evaluate the applicability of EMTP-like programs to the transient analysis of buried conductors. Transient pulse propagation in time domain based on finite difference time domain (FDTD) method of solution of TL equations is also discussed for a future inclusion of non-linear phenomena, like soil ionization and arcing/breakdown mechanisms, in the soil. The analysis presented could be useful in estimating surge propagation characteristics of buried wires for appropriate insulation coordination and transient protection.

  • 77.
    Theethayi, Nelson
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Division for Electricity and Lightning Research.
    Thottappillil, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Division for Electricity and Lightning Research.
    Yirdaw, Tegegne
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Division for Electricity and Lightning Research.
    Liu, Yaqing
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Division for Electricity and Lightning Research.
    Götschl, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Division for Electricity and Lightning Research.
    Montano, Raul
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Division for Electricity and Lightning Research.
    Experimental Investigation of Lightning Transients Entering a Swedish Railway Facility2007In: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 22, no 1, p. 354-363Article in journal (Refereed)
    Abstract [en]

    Transients caused by lightning in railway facilities have not received much attention. In this paper, we describe the measurements of lightning transients entering a Swedish railway facility during the summer of 2003. The measurements of the transients were made in a technical house that provides an uninterrupted power supply for telecommunication systems and the signal systems. An analysis of the data has shown that transients in excess of 7 kV (peak to peak) can appear across the line-to-neutral supply system due to an indirect lightning strike. Some typical characteristics of the line-to-neutral transient voltages in terms of stroke locations and stroke amplitudes are presented. Further, from the experimental data, an empirical relation for predicting the line-to-neutral transient voltage in terms of stroke location and stroke current amplitude is obtained. Simple induced voltage calculations are presented to identify the levels of induced voltages appearing at the input of the technical house. The influence of ground conductivity on those induced voltages is also presented. The information presented in the paper is an important electromagnetic-compatibility issue associated with the lightning protection for railway systems.

  • 78.
    Thottappilli, Rajeev
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Theethayi, Nelson
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Realistic sources for modeling lightning interaction with towers2006In: First International Symposium on Lightning Physics and Effects: EU COST P18, Vienna, April 3-4, 2006, p. 36-Conference paper (Other academic)
  • 79.
    Thottappillil, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. elektricitetslära och åskforskning.
    EMC Aspects of Lightning Interaction with Communication Towers2006Conference paper (Other academic)
  • 80.
    Thottappillil, Rajeev
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    On the non-uniqueness of the electric field components –static, induction or intermediate, and radiation - from extended source distributions2004In: Euro Electromagnetics (EUROEM), Magdeburg, Germany, 2004Conference paper (Other scientific)
  • 81.
    Thottappillil, Rajeev
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Cooray, Vernon
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Theethayi, Nelson
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Lightning Return Stroke Models and Electromagnetic Field Computation2007Conference paper (Refereed)
  • 82.
    Thottappillil, Rajeev
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Montano, Raul
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Månsson, Daniel
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Response of Surge Protective Devices to Very Fast Transient Conducted Pulses2004In: Euro Electromagnetics (EUROEM), Magdeburg, Germany, 2004Conference paper (Other scientific)
  • 83.
    Thottappillil, Rajeev
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Månsson, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Bäckström, Mats
    Response of Electrified Railway Facilities to Intentional Electromagnetic Interference: Review of Research at Uppsala University2008In: 2008 ASIA-PACIFIC SYMPOSIUM ON ELECTROMAGNETIC COMPATIBILITY AND 19TH INTERNATIONAL ZURICH SYMPOSIUM ON ELECTROMAGNETIC COMPATIBILITY, VOLS 1 AND 2, 2008, p. 291-294Conference paper (Refereed)
    Abstract [en]

    A research program is being conducted at Uppsala University, Sweden, to investigate the possible susceptibility of civilian systems and networks to intentional electromagnetic interference (IEMI), with emphasis on the Swedish railway network. This paper reviews the details of the research program and some of the results.

  • 84.
    Thottappillil, Rajeev
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Månsson, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Bäckström, Mats
    Susceptibility of Electrified Railway Facilities to Intentional Electromagnetic Interference2008Conference paper (Other academic)
  • 85.
    Thottappillil, Rajeev
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Månsson, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Bäckström, Mats
    Susceptibility of Electrified Railway to Intentional Electromagnetic Interference: Research in Sweden2008Conference paper (Other academic)
  • 86.
    Thottappillil, Rajeev
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Månsson, Daniel
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Theethayi, Nelson
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Bäckström, Mats
    Nilssson, Tony
    Undén, Göran
    Nordström, Barbro
    Bohlin, Per
    Lindeberg, Per Anders
    Hellström, Ulf
    Lindeberg, Peter
    Bohlin, Georg
    Zitnik, Mihael
    Ekenberg, Lise
    Response of Civilian Facilities to Intentional Electromagnetic Interference (IEMI), with Emphasis on the Swedish Railway Network2005In: EMC Europe Workshop, Rome, Italy. Sept. 19-21, 2005, p. 66-68Conference paper (Other scientific)
  • 87.
    Thottappillil, Rajeev
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Rakov, V.A.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Calculation Of Lightning Electromagnetic Fields: A Review2005In: XXVIIIth General Assembly of International Union of Radio Sciences, New Delhi, India, October 23-29, 2005Conference paper (Refereed)
  • 88.
    Thottappillil, Rajeev
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Rakov, Vladimir
    Equivalent Approaches to Computing Electromagnetic Fields from an Extending Lightning Discharge2007Conference paper (Refereed)
  • 89.
    Thottappillil, Rajeev
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. elektricitetslära och åskforskning.
    Rakov, Vladimir
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. elektricitetslära och åskforskning.
    Expressions for far fields at high altitudes from lightning return stroke2006In: Proceedings of International Conference of Grounding and Earthing Ground 2006 and International Conference on Lightning Physics and Effects 2nd LPE, Nov 26-29, 2006, Maceio, Brazil, paper no 18, 2006Conference paper (Refereed)
  • 90.
    Thottappillil, Rajeev
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Rakov, Vladimir
    Department of Electrical and Computer Engineering, University of Florida.
    Review of Three Equivalent Approaches for Computing Electromagnetic Fields from an Extending Lightning Discharge2007In: Journal of Lightning Research, ISSN 1652-8034, Vol. 1, p. 90-110Article in journal (Refereed)
    Abstract [en]

    Three different general approaches for calculating the electromagnetic fields at any point in space from a lightning return stroke, which is modelled as an extending linear antenna, are reviewed and compared. In the first approach, known as the dipole approach, the electric field is completely expressed in terms of the retarded current on the lightning channel and in the second approach the electric field is expressed in terms of the current and local charge density in retarded time. In the third approach the electric field is completely expressed in terms of the apparent charge density, that is, the charge density that would be seen in the channel by a remote observer at retarded time. In general, apparent charge density is different from the local charge density in retarded time. Analytically these three electric field expressions are equivalent, which is verified numerically also. Besides, it is shown that the magnetic field can be completely expressed in terms of the apparent charge density, as opposed to the traditional expression for magnetic field involving only the retarded current. It is also shown that the division of electric field into static, induction, and radiation field components are not unique in the first two approaches, even though the total field is the same. Numerical calculations of electric fields and magnetic fields predicted by the transmission line (TL) model of the return stroke are presented at different distances from origin and at different angles to the vertical for different return stroke speeds. This also provides a numerical verification of the general electric and magnetic field expressions from the third approach against the first approach.

  • 91.
    Thottappillil, Rajeev
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Rakov, Vladimir A.
    Comment on "Radio frequency radiation beam pattern of lightning return strokes: A revisit to theoretical analysis" by Xuan-Min Shao, Abram R. Jacobson, and T. Joseph Fitzgerald2005In: Journal of Geophysical Research, Vol. 110, no D24105, p. 1-4Article in journal (Refereed)
  • 92.
    Thottappillil, Rajeev
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Rakov, Vladimir A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Far Fields at an Elevation from Lightning Return Strokes2006In: First International Symposium on Lightning Physics and Effects, 2006, p. 21-Conference paper (Other academic)
  • 93.
    Thottappillil, Rajeev
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Rakov, Vladimir
    University of Florida.
    Theethayi, Nelson
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Expressions for far electric fields produced at an arbitrary altitude by lightning return strokes2007In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 112, no D16, p. D16102-Article in journal (Refereed)
    Abstract [en]

    Electromagnetic fields produced at high altitudes by return strokes in cloud-to-ground lightning are needed in studies of transient luminous events in the mesosphere. Such calculations require the use of a lightning return stroke model. Two of the widely used return stroke models are (1) the modified transmission line model with exponential decay (MTLE) of current with height and (2) the modified transmission line model with linear decay (MTLL) of current with height. In this paper, simplified expressions based on the MTLE and MTLL models are derived for calculating far (radiation) electric fields produced at an arbitrary elevation angle by lightning return strokes. It is shown that different (for example, containing either spatial or time integral), but equivalent equations can be derived for each of the models. Predictions of simplified expressions are compared with electric fields computed using exact expressions, including all the field components, and the validity of simplified expressions for distances that are much greater than the radiating channel length is confirmed.

  • 94.
    Thottappillil, Rajeev
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Rakov, Vladimir
    Uman, Martin
    Exact expressions in the time domain for electric fields from an extending lightning discharge in terms of the charge density2004In: Progress in Electromagnetic Research Symposium, Pisa, Italy, March 28-31, 2004Conference paper (Refereed)
  • 95.
    Thottappillil, Rajeev
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Theethayi, Nelson
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Modeling Lightning Attachment to Tall Towers2007In: Piers 2007 Beijing: Progress in Electromagnetics Research Symposium, Pts I and II, Proceedings / [ed] Kong, JA, 2007, p. 1051-1056Conference paper (Refereed)
    Abstract [en]

    Lightning return stroke resulting from the downward leader attachment to tall towers is modeled as a point current source in series with the lightning channel and tower. Assuming a quasi-transverse electromagnetic field structure, expressions for the current at the top of the tower, at the base of the tower and along the tower are presented.

  • 96.
    Thottappillil, Rajeev
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. elektricitetslära och åskforskning.
    Theethayi, Nelson
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. elektricitetslära och åskforskning.
    Realistic sources for modeling lightning attachment to towers2006In: Proceedings of International Conference of Grounding and Earthing Ground 2006 and International Conference on Lightning Physics and Effects 2nd LPE, Nov 26-29, 2006, Maceio, Brazil, paper no 4, 2006Conference paper (Refereed)
  • 97.
    Thottappillil, Rajeev
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. elektricitetslära och åskforskning.
    Theethayi, Nelson
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. elektricitetslära och åskforskning.
    Cooray, Vernon
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. elektricitetslära och åskforskning.
    Lightning Return Stroke Models and Electromagnetic Field Computation, in Tutorial on EMC aspects of Lightning2006Conference paper (Other academic)
  • 98.
    Thottappillil, Rajeev
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Theethayi, Nelson
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Hågård, T
    Sjöberg, K
    Grape, Ulf
    Security Assessment For Ringhals Nuclear Power Plant, Unit 1, With Respect To Lightning Strikes2008Conference paper (Refereed)
  • 99.
    Thottappillil, Rajeev
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Uman, M. A.
    Theethayi, Nelson
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    TEM field structure of electric and magnetic fields from a semi-infinite vertical thin-wire antenna above a conducting plane2007In: Ultra-Wideband, Short-Pulse Electromagnetics 7 / [ed] Sabath F, Mokole EL, Schenk U, Nitsch D, 2007, p. 33-40Conference paper (Refereed)
    Abstract [en]

    Investigation is carried out on the electric and magnetic field structures around a semi-infinite thin-wire antenna vertically placed above a perfectly conducting ground plane. It is shown that the electric and magnetic fields due to a time-varying point source at the bottom of the antenna have a field structure identical to that for the case of a uniform line charge and a uniform current, and have a spherical transverse electromagnetic (TEM) field structure. Simple, but exact, expressions for the electric and magnetic fields are derived, and it is shown that the general expressions for the electric and magnetic fields from time-varying sources on a thin wire semi-infinite antenna reduce to the same simple expressions if the source is assumed to be a current or charge pulse traveling at the speed of light and without attenuation. In that case, the Poynting vector indicates energy flow in the radial direction from the source at the bottom of the antenna. That is, in this ideal case the only source of radiation is the point source at the bottom of the antenna and the vertical antenna itself does not radiate. The wave impedance at all distances from this antenna is the free space impedance. Further, a general discussion on the TEM type solutions in different structures containing two perfect conductors is provided.

  • 100.
    Thottappillil, Rajeev
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Uman, Martin
    Electric and magnetic fields from a semi-infinite vertical thin-wire antenna above a conducting plane2004In: Progress in Electromagnetic Research Symposium, Pisa, Italy, March 28-31, 2004Conference paper (Refereed)
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