On: “Transient electromagnetic field computations for polygonal loops on layered earths” by A. P. Raiche (GEOPHYSICS, 52, 785–793, June 1987).

Geophysics ◽  
1989 ◽  
Vol 54 (11) ◽  
pp. 1501-1501
Author(s):  
Rainer Ignetik
Keyword(s):  
Electromagnetic Field ◽  
Electromagnetic Fields ◽  
Efficient Method ◽  
Time Domain ◽  
Integration Scheme ◽  
Important Work ◽  
Extended Source ◽  
Transient Electromagnetic ◽  
Efficient Calculation ◽  
The Time Domain

Raiche has overlooked the related and important work of Boerner and West (1984). Their work deals with the efficient calculation of electromagnetic fields of any extended source, including polygonal loops. Raiche’s complicated three‐level integration scheme could have been avoided by using Boerner and West’s more efficient method in the frequency domain, followed by fast transformation to the time domain by convolution filtering. These techniques are well known and used frequently to compute transients in complicated 3‐D models.

scholarly journals Transient Electromagnetic Field Coupling to Buried Thin Wire Configurations: Antenna Model versus Transmission Line Approach in the Time Domain

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Dragan Poljak ◽  
Silvestar Šesnić ◽  
Khalil El-Khamlichi Drissi ◽  
Kamal Kerroum ◽  
Sergey Tkachenko
Keyword(s):  
Electromagnetic Field ◽  
Transmission Line ◽  
Time Domain ◽  
Wire Antenna ◽  
Straight Wire ◽  
Field Coupling ◽  
Transient Electromagnetic ◽  
Model Versus ◽  
The Time Domain ◽  
Antenna Model

The paper examines the antenna model for the transient analysis of electromagnetic field coupling to straight wire configurations buried in a lossy half-space. The wire antenna theory (AT) model is implemented directly in the time domain and it is based on the corresponding space-time Pocklington integrodifferential equation. The solution of the Pocklington equation is carried out analytically. The obtained results are compared against the results calculated via the transmission line (TL) approach. The TL approach is based on the telegrapher’s equations, which are solved using the modified transmission line method (MTLM) and Finite Difference Time Domain (FDTD) technique, respectively. Some illustrative computational examples for buried straight wire scatterer and horizontal grounding electrode are given throughout this work.

Analytical Expressions for Electromagnetic Fields Associated with the Inclined Lightning Channels in the Time Domain

2012 ◽  
Vol 40 (4) ◽  
pp. 414-438 ◽  
Author(s):  
Mahdi Izadi ◽  
Mohd Zainal Ab Kadir ◽  
Chandima Gomes ◽  
Wan Fatin Hamamah Wan Ahmad
Keyword(s):  
Electromagnetic Fields ◽  
Time Domain ◽  
The Time Domain ◽  
Analytical Expressions

Electromagnetic modeling of 3-D sources over 2-D inhomogeneities in the time domain

Geophysics ◽  
1992 ◽  
Vol 57 (8) ◽  
pp. 994-1003 ◽  
Author(s):  
Michael Leppin
Keyword(s):  
Differential Equations ◽  
Diffusion Equation ◽  
Time Domain ◽  
Magnetic Induction ◽  
Host Rock ◽  
Vertical Component ◽  
Wavenumber Domain ◽  
Transient Electromagnetic ◽  
Wide Range ◽  
The Time Domain

A numerical method is presented by which the transient electromagnetic response of a two‐dimensional (2-D) conductor, embedded in a conductive host rock and excited by a rectangular current loop, can be modeled. This 2.5-D modeling problem has been formulated in the time domain in terms of a vector diffusion equation for the scattered magnetic induction, which is Fourier transformed into the spatial wavenumber domain in the strike direction of the conductor. To confine the region of solution of the diffusion equation to the conductive earth, boundary values for the components of the magnetic induction on the ground surface have been calculated by means of an integral transform of the vertical component of the magnetic induction at the air‐earth interface. The system of parabolic differential equations for the three magnetic components has been integrated for 9 to 15 discrete spatial wavenumbers ranging from [Formula: see text] to [Formula: see text] using an implicit homogeneous finite‐difference scheme. The discretization of the differential equations on a grid representing a cross‐section of the conductive earth results in a large, sparse system of linear equations, which is solved by the successive overrelaxation method. The three‐dimensional (3-D) response has been computed by an inverse Fourier transformation of the cubic spline interpolated scattered magnetic induction in the wavenumber domain using a digital filtering technique. To test the algorithm, responses have been computed for a two‐layered half‐space and a vertical prism embedded in a conductive host rock. These examples were then compared with results obtained analytically or numerically using frequency‐domain finite‐element and time‐domain integral equation methods. The new numerical procedure gives satisfactory results for a wide range of 2-D conductivity distributions with conductivity ratios exceeding 1:100, provided the grid is sufficiently refined at the corners of the conductivity anomalies.

On: “Time‐Dependent Electromagnetic Fields of an Infinite, Conducting Cylinder Excited by a Long Current‐Carrying Cable” by S. K. Verma (GEOPHYSICS, April 1973, p. 369–379)

Geophysics ◽  
1974 ◽  
Vol 39 (3) ◽  
pp. 355-355
Author(s):  
Shri Krishna Singh
Keyword(s):  
Magnetic Field ◽  
Frequency Domain ◽  
Electric Current ◽  
Electromagnetic Fields ◽  
Time Domain ◽  
Static Solution ◽  
Transverse Magnetic ◽  
Time Dependent ◽  
Axially Symmetric ◽  
The Time Domain

In this paper Verma obtains a time‐domain solution by inverting the frequency‐domain solution given by Wait (1952). However, it has been recently pointed out by Singh (1973a) (see also Wait, 1973) that there is an error in the quasi‐static solution of Wait. Wait neglected the axially symmetric inducted electric current in the cylinder giving rise to a secondary transverse magnetic field outside (the n=0 term in the scattered wavefield). Singh (1973a) has shown that this term dominates. [It should be noted that Wait in his other works on the cylinder retains this term (e.g., Wait, 1959).] It is clear that this term would be dominant in the time‐domain also. This has been shown by Singh (1972, 1973b). Since the theoretical solution given by Verma in the paper under discussion is incomplete, his interpretation schemes are meaningless.

scholarly journals Electromagnetic fields in linear and nonlinear chiral media: a time-domain analysis

2004 ◽  
Vol 2004 (6) ◽  
pp. 471-486 ◽  
Author(s):  
Ioannis G. Stratis ◽  
Athanasios N. Yannacopoulos
Keyword(s):  
Electromagnetic Fields ◽  
Time Domain ◽  
Linear Time ◽  
Time Domain Analysis ◽  
Local Approximation ◽  
Well Posedness ◽  
Chiral Media ◽  
The Time Domain ◽  
Nonlocal Media ◽  
Nonlocal Medium

We present several recent and novel results on the formulation and the analysis of the equations governing the evolution of electromagnetic fields in chiral media in the time domain. In particular, we present results concerning the well-posedness and the solvability of the problem for linear, time-dependent, and nonlocal media, andresults concerning the validity of the local approximation of the nonlocal medium (optical response approximation). The paper concludes with the study of a class of nonlinear chiral media exhibiting Kerr-like nonlinearities, for which the existence of bright and dark solitary waves is shown.

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