Farhad Rachidi-Haeri

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Traditional location methods such as time of arrival and direction of arrival have been widely used to locate transient radiation sources. However, these approaches neglect the directional radiation pattern of the sources. Locating directional sources is a ...

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 exp

The ground impedance matrix elements of a multiconductor overhead transmission line do not have analytical inverse Fourier transforms in the time domain. Thus, in general, the ground transient resistance matrix elements are to be determined numerically. Using the low-frequency approximation analytical expressions are available for the ground transient resistance. These expressions present however a singularity at t = 0 and require a careful treatment in a direct time domain analysis. In this paper, we show

An N-port equivalent circuit approach is adopted to model a multipoint grounding system, N being the number of injection points. A methodology is proposed to determine the parameters of the N-port equivalent circuit from either numerical simulations or exp ...

We discuss the transmission line (TL) theory and its application to the problem of lightning electromagnetic field coupling to TLs. We start with the derivation of the general field-to-TL coupling equations for the case of a single-wire line above a perfec ...

Lightning striking tall towers is mainly of the upward lightning type, which is characterized by the absence of a first return stroke and the presence of an initial continuous current (ICC) with or without superimposed pulses. The Santis Tower is 124 m tal ...

X-rays have been observed in natural downward cloud-to-ground lightning for over 20 years and in rocket-triggered lightning for slightly less. In both cases, this energetic radiation has been detected during the stepped and dart leader phases of downward n ...

The lightning discharge current is characterized by a high-frequency spectrum extending from DC to about 10 MHz. The calculation of the grounding impedance is one of the most important aspects of designing lightning protection systems. The search for analy ...

We present simultaneous current and wideband electric field waveforms at 380 km associated with upward lightning flashes initiated from the Santis Tower, Switzerland. To the best of our knowledge, the dataset presented in this study includes the first simu ...

Researchers working on the problem of the coupling of lightning electromagnetic fields to overhead lines have suggested that, if the formulation of the coupling problem given by Agrawal et al. is adopted, only the horizontal component of the electric field drives current in the direction of the line and that the vertical component induces current only at the vertical terminations. All of these studies assume that the wires are perfectly horizontal. In practice, however, the wires exhibit sag. A theoretical

The electrodynamics of the Terrestrial Gamma Ray Flash (TGF) are not fully understood but the last decade has seen compelling observations in lightning leader (+IC) radio emission that have linked a subset of TGF satellite observations with unique waveform ...

In this paper, we analyze the electric field at ground level during the first stage of triggered lightning experiments, i.e., during the rocket ascent and prior to the lightning initiation. At distances of some tens of meters from the triggering wire, the ...

The calculation or voltages induced by indirect lightning on multiconductor lines has been the subject of several studies. The reported conclusions are not always in agreement with each other. In this paper, using a modeling procedure presented in a previous work, we study the shielding effect due to mutual coupling among the conductors of a three-phase line and between the ground wires and the line conductors. The results are compared with those published by other authors, and explanations of the disagreem

The proper characterization of lightning electric and magnetic fields is very important for a number of reasons, such as the study and design of lightning protection and the validation of return stroke models. Also, an accurate late time response of the se ...

Observations and theoretical principles indicate that electromagnetic waves, including light, propagate more slowly in dielectric media than in a vacuum. This behavior is elegantly described by Maxwell's equations, which account for material‐specific permittivity and permeability. According to the principle of superposition, the net electromagnetic wave within a dielectric medium results from the combination of the incident wave and secondary waves generated by the medium's interaction with the incident wav

This paper presents an analysis of lightning return strokes to tall structures. The interaction of lightning with a tall structure is modeled using the antenna theory. The finite ground conductivity as well as the buried grounding system of the tall struct ...

The response of local lightning to local surface temperature is examined near the Säntis mountain (2502 m ASL) in the eastern Swiss Alps during the first of the two hiatuses in global warming covering the time periods 1940-1972 and 1998-2014. The mountain ...

Disturbances in low-voltage control circuits in substations and power plants occur due to lightning or switching surges. Adequate protection of electronic devices in low-voltage control circuits requires the capacity to predict surge phenomena and to evalu ...

Based on the transmission line approximation, three different equivalent formulations have been proposed for evaluating the interaction between an external electromagnetic field and a transmission line. The difference among these 'coupling' formulations, which are summarized for the case of a lossless line, lies essentially in the representation of the source terms as a function of the external electromagnetic field components. In the paper we show that the contribution of a given electromagnetic field comp

The calculation of voltages induced by indirect lightning on multiconductor overhead power lines has been the subject of several studies. The reported conclusions are not always in agreement with each other. In this paper, using a modeling procedure presented in a previous work, the authors study the shielding effect due to mutual coupling among the conductors of a three-phase power line and between the ground wires and the line conductors. The results are compared with those published by other authors, and

Farhad Rachidi-Haeri

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Locating Transient Directional Sources in Free Space Based on the Electromagnetic Time Reversal Technique

On tower impedances for transient analysis

A new expression for the ground transient resistance matrix elements of multiconductor overhead transmission lines

On the Concept of Grounding Impedance of Multipoint Grounding Systems

A Review of Field-to-Transmission Line Coupling Models With Special Emphasis to Lightning-Induced Voltages on Overhead Lines

LMA Observation of Upward Flashes at Santis Tower: Preliminary Results

Direct observations of X-rays produced by upward positive lightning

High-frequency response of a hemispherical grounding electrode

Analysis of lightning-ionosphere interaction using simultaneous records of source current and 380 km distant electric field

Overvoltages induced by lightning on overhead power and distribution lines with sag

Mountaintop gamma ray observations of two TGFs at the Santis Tower, Switzerland with coincident radio waveforms characteristic of a RREA current pulse

A model for the evaluation of the electric field associated with the lightning-triggering rocket wire and its corona

Response of multiconductor power lines to nearby lightning return stroke electromagnetic fields

Compensation of the Instrumental Decay in Measured Lightning Electric Field Waveforms

Conceptual Links Between the Ewald‐Oseen Extinction Theorem and Return Stroke Modeling

Lightning strikes to elevated structures: influence grounding conditions on currents and electromagnetic fields

An Analysis of Lightning Activity in the Säntis Region through the Big Hiatus in Global Warming

A Technique for Calculating Voltages Induced on Twisted-Wire Pairs Using the FDTD Method

On the contribution of the electromagnetic field components in field-to-transmission line interaction

Response of multiconductor power lines to nearby lightning return stroke electromagnetic fields