scholarly journals Electromagnetic Pulse of a Vertical Electric Dipole in the Presence of Three-Layered Region

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
D. Cheng ◽  
T. T. Gu ◽  
P. Cao ◽  
T. He ◽  
K. Li
Keyword(s):  
Time Domain ◽  
Electric Dipole ◽  
Delta Function ◽  
Observation Point ◽  
Perfect Conductor ◽  
Transient Field ◽  
Planar Surface ◽  
Vertical Electric Dipole ◽  
Trapped Surface ◽  
The Time Domain

Approximate formulas are obtained for the electromagnetic pulses due to a delta-function current in a vertical electric dipole on the planar surface of a perfect conductor coated by a dielectric layer. The new approximated formulas for the electromagnetic field in time domain are retreated analytically and some new results are obtained. Computations and discussions are carried out for the time-domain field components radiated by a vertical electric dipole in the presence of three-layered region. It is shown that the trapped-surface-wave terms should be included in the total transient field when both the vertical electric dipole and the observation point are on or near the planar surface of the dielectric-coated earth.

scholarly journals Electromagnetic Pulse Generated by a Horizontal Electric Dipole over a Perfect Conductor Covered with a Dielectric Layer

2018 ◽  
Vol 17 ◽  
pp. 01010
Author(s):  
Juan Zheng ◽  
Tong He ◽  
Ping Cao ◽  
Zhuhong Lin ◽  
Kai Li
Keyword(s):  
Dielectric Layer ◽  
Electromagnetic Pulse ◽  
Approximate Expression ◽  
Delta Function ◽  
Perfect Conductor ◽  
Transient Field ◽  
Planar Surface ◽  
Horizontal Electric Dipole ◽  
Trapped Surface ◽  
Microstrip Circuit

In this paper, the electromagnetic pulse due to a delta-function current excitation has been derived on the planar surface of a perfect conductor coated by a dielectric layer. The approximate expression of wave component is obtained when both the transmitting source and the receiving antennas are located on the surface of the dielectric. When the thickness of the intermediate layer is subjected to the condition of k1l<<0.6, this physical model is applied to the microstrip circuit. Analysis and computations of the wave components are carried out on the microstrip circuit, including the surface trapped wave vector which had been ignored in former studies. It is shown that the trapped-surface-wave terms should have been taken into consideration as the main contribution in total transient field in the far-field radiations.

scholarly journals Evaluation of the Trapped Surface Wave of a Vertical Electric Dipole Based on Undetermined Coefficient Method in the Presence of N-Layered Region: A Graphical Approach

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Hong Lei Xu ◽  
Ting Ting Gu ◽  
Yong Zhu ◽  
Xiao Wei ◽  
Liang Sheng Li ◽  
...  
Keyword(s):  
Surface Wave ◽  
Electric Dipole ◽  
Observation Point ◽  
Dipole Source ◽  
Graphical Approach ◽  
Vertical Electric Dipole ◽  
Undetermined Coefficient ◽  
Trapped Surface ◽  
Coefficient Method ◽  
Undetermined Coefficient Method

In previous studies, the trapped surface wave, which is defined by the residue sums, has been addressed in the evaluation of the Sommerfeld integrals describing electromagnetic field of a vertical dipole in the presence of three-layered or four-layered region. But unfortunately, the existing computational scheme cannot provide analytical solution of the field in the presence of the N-layered region when N > 4. The scope of this paper is to overcome the limitations in root finding algorithm implied by the previous approach and provide solution of poles in stratified media. A set of pole equations following with explicit expressions are derived based on the undetermined coefficient method, which enable a graphical approach to obtain initial values of real roots. Accordingly, the generated trapped surface wave components are computed when both the observation point and the electric dipole source are on or near the surface of a dielectric-coated conductor. Validity, efficiency, and accuracy of the proposed method are illustrated by numerical examples.

scholarly journals Simulation of the Vertical-Vertical Controled Source Electromagtic Method

2021 ◽  
Author(s):  
Danusa Souza ◽  
Victor Souza ◽  
Marcos Silva
Keyword(s):  
Electromagnetic Field ◽  
Time Domain ◽  
Electric Dipole ◽  
Three Dimensional ◽  
Comsol Multiphysics ◽  
Controlled Source ◽  
Main Application ◽  
Vertical Electric Dipole ◽  
Acquisition Mode ◽  
Complex Geology

<div>Modeling of the Vertical-Vertical Controled Source Electromagtic Method (VVCSEM) on COMSOL Multiphysics. The VVCSEM method is, strictly speaking, an MCSEM (Marine Controlled Source ElectroMagnetic) that uses a vertical electric dipole as source, vertically oriented receivers, and time domain acquisition mode. Its main application is reservoir monitoring, reducing ambiguities encountered by conventional seismic and minimizing exploration risks in fields with complex geology. The present study shows the results of three-dimensional (3D) VVCSEM modeling built in COMSOL Multiphysics, aiming to analyze the electromagnetic field responses in different models and configurations. The VVCSEM proved to be efficient in detecting the proposed resistive anomalies, as expected and described in the literature.</div>

The 2D coastal effect on marine time domain electromagnetic measurements using broadside dBz/dt of an electrical transmitter dipole

Geophysics ◽  
2011 ◽  
Vol 76 (2) ◽  
pp. F101-F109 ◽  
Author(s):  
Mark Goldman ◽  
Eldad Levi ◽  
Buelent Tezkan ◽  
Pritam Yogeshwar
Keyword(s):  
Time Domain ◽  
Electric Dipole ◽  
Field Measurements ◽  
Resolving Power ◽  
Receiver Coil ◽  
Vertical Electric Dipole ◽  
Horizontal Electric Dipole ◽  
Time Domain Electromagnetic ◽  
Actual Field ◽  
Receiver Arrays

Galvanic transmitter-receiver arrays commonly are used in marine controlled-source electromagnetic (CSEM) exploration of electrically resistive targets such as hydrocarbons, gas hydrates, etc. These arrays utilize vertical electric currents and, as a result, are expected to provide better resolving capability for exploring subhorizontal resistive structures than arrays including horizontal coils. If, however, a subseafloor resistive target is located within a transition zone at distances of up to a few kilometers from the shoreline, the 2D sea-coast resistivity contrast significantly affects the resolving capability of the measurements. An extensive multidimensional modeling supported by numerous offshore measurements showed that the inductive array consisting of a horizontal electric dipole transmitter and a broadside vertical magnetic dipole (horizontal coil) receiver exhibits much better resolving power in time domain compared to all other arrays but those with a vertical electric dipole. This effect takes place only if a short offset receiver coil is located between the transmitter dipole and the coast. If the coil is located at the seaside of the transmitter dipole, the signal lacks the resolving capability almost entirely. At large offsets, the resolving capability of the measurements is relatively low at both sides of the transmitter dipole. Although actual field measurements were conducted only to explore a shallow target (fresh subseafloor groundwater body), calculations show that the same phenomenon exists in case of deep targets (e.g., hydrocarbons).

scholarly journals Time-Domain Analytical Expression for Near Fields of Arbitrarily Oriented Electric Dipole and Its Application

2017 ◽  
Vol 2017 ◽  
pp. 1-8
Author(s):  
Qian Yang ◽  
Bing Wei ◽  
Xinbo He ◽  
Minghao Gong
Keyword(s):  
Time Domain ◽  
Electric Dipole ◽  
Near Field ◽  
Wide Band ◽  
Frequency Transformation ◽  
Numerical Examples ◽  
Electromagnetic Problems ◽  
Time Frequency ◽  
The Time Domain ◽  
Analytical Expressions

The near fields of electric dipole are commonly used in wide-band analysis of complex electromagnetic problems. In this paper, we propose new near field time-domain expressions for electric dipole. The analytical expressions for the frequency-domain of arbitrarily oriented electric dipole are given at first; next we give the time-domain expressions by time-frequency transformation. The proposed expressions are used in hybrid TDIE/DGTD method for analysis of circular antenna with radome. The accuracy of the proposed algorithm is verified by numerical examples.

On the propagation of a pulse through an antipode

1969 ◽  
Vol 47 (12) ◽  
pp. 1327-1330 ◽  
Author(s):  
James R. Wait
Keyword(s):  
Time Domain ◽  
Pulse Shape ◽  
Dipole Source ◽  
Transient Field ◽  
Idealized Model ◽  
Time Domain Response ◽  
The Time Domain ◽  
Strong Distortion

The time domain response of the fields in the vicinity of an axial caustic is calculated. The idealized model is a spherical concentric cavity with perfectly conducting walls. It is shown that the transient field, in the vicinity of the antipode of a dipole source, exhibits a strong distortion in the pulse shape.

Direct time‐domain calculation of the transient response for a rectangular loop over a two‐layer medium

Geophysics ◽  
1987 ◽  
Vol 52 (7) ◽  
pp. 997-1006 ◽  
Author(s):  
Mark M. Goldman ◽  
David V. Fitterman
Keyword(s):  
Magnetic Field ◽  
Time Domain ◽  
Electric Dipole ◽  
Late Stage ◽  
Apparent Resistivity ◽  
Time Derivative ◽  
Vertical Magnetic Field ◽  
First Case ◽  
Layer Medium ◽  
The Time Domain

The time derivative of the vertical magnetic field due to an electric dipole on the surface of a two‐layer half‐space is computed directly in the time domain by applying the residue theorem to the analytic field expressions. The second layer must be either insulating [Formula: see text] or perfectly conducting [Formula: see text]. The first case can be used to estimate the response of a conductive overburden for mining exploration problems. The second case is useful in explaining the overshoot seen in transient sounding voltage apparent‐resistivity curves when a conductive basement underlies a resistive first layer. In the late stage, the time derivative of the vertical magnetic field decays as [Formula: see text] and the late‐stage apparent resistivity increases as t for [Formula: see text], while for [Formula: see text], these quantities behave as [Formula: see text] and [Formula: see text], respectively, where [Formula: see text], [Formula: see text], is the first‐layer conductivity, [Formula: see text] is the first‐layer thickness, and [Formula: see text]. The electric dipole expressions are integrated to obtain solutions for rectangular loops. Numerical results for a rectangular loop on a layer over an insulating basement (overburden case) show that the overburden response is initially positive inside the loop and negative outside the loop. At later times, the response outside the loop becomes positive. The thinner the overburden layer, the greater the maximum response.

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