ELECTROMAGNETIC FIELDS OF A TRANSIENT MAGNETIC DIPOLE ON THE EARTH’S SURFACE

Geophysics ◽  
1959 ◽  
Vol 24 (1) ◽  
pp. 89-108 ◽  
Author(s):  
Bimal Krishna Bhattacharyya
Keyword(s):  
Magnetic Fields ◽  
Step Function ◽  
Displacement Current ◽  
Time Interval ◽  
Initial Amplitude ◽  
Impedance Function ◽  
Circular Loop ◽  
Mutual Impedance ◽  
The Earth ◽  
Electric And Magnetic Fields

Transient electric and magnetic fields close to the surface of the earth, as developed by a step‐function current flowing in a circular loop of wire, have been determined. The effect of the insulating air region is fully taken into account. It is observed that the air region has an appreciable influence on the fields over the surface of the earth. The effect of displacement current within the earth has also been considered. Expressions of electric and magnetic fields have been utilized to determine (a) the mutual impedance function between the primary loop and a small length of wire and (b) the voltage induced in a secondary loop. Both these functions are found to have appreciable magnitudes only during the time interval between the arrival of the wave travelling through air and that of the wave via the conducting medium. From a study of this duration and the initial amplitude of either of the two functions, it is possible to obtain values of conductivity and permittivity of the earth. Curves have been plotted to depict the nature of variation of these functions with time for different values of the electric constants of the earth.

ELECTROMAGNETIC FIELDS OF A VERTICAL MAGNETIC DIPOLE PLACED ABOVE THE EARTH’S SURFACE

Geophysics ◽  
1963 ◽  
Vol 28 (3) ◽  
pp. 408-425 ◽  
Author(s):  
B. K. Bhattacharyya
Keyword(s):  
Electromagnetic Fields ◽  
Current Source ◽  
Step Function ◽  
Impedance Function ◽  
Low Frequencies ◽  
Primary Loop ◽  
Mutual Impedance ◽  
The Earth ◽  
Receiving Antenna ◽  
Rate Of Decay

Electromagnetic fields due to a small loop antenna placed above the surface of a homogeneous and isotropic earth have been calculated. The effect of both the conduction and displacement currents are taken into account. Because of the complexity of the functions defining the fields, expressions valid separately for high and low frequencies are developed for the electric and magnetic field components. These expressions are then utilized to determine, for a step‐function current source, (a) the mutual impedance function [Formula: see text] between the primary loop and a small length of wire and (b) the voltage v(t) induced in a secondary loop. Two parameters are used to fix the locations of the primary loop and the receiving antenna with respect to the earth. A number of curves are plotted showing the mutual impedance function and the voltage function against time for different values of the parameters and the conductivity and the permittivity of the earth. With increase in either the conductivity or the permittivity, the amplitude and the rate of decay of the two functions decrease appreciably. However, the amplitudes of both [Formula: see text] and v(t) become smaller and the rate of decay higher as the receiving antenna is gradually lifted vertically from the ground. For all values of permittivity, the amplitude of the mutual impedance rises to a maximum with the horizontal separation between the two antennas before beginning to decrease, but at the same time the rate of decay of the transient becomes faster. With increase in the horizontal separation, the amplitude of the voltage function decreases inversely as the fifth power of the distance between the image of the transmitting dipole and the receiving antenna, but the rate of decay increases markedly.

PROPAGATION OF AN ELECTRIC PULSE THROUGH A HOMOGENEOUS AND ISOTROPIC MEDIUM

Geophysics ◽  
1957 ◽  
Vol 22 (4) ◽  
pp. 905-921 ◽  
Author(s):  
Bimal Krishna Bhattacharyya
Keyword(s):  
Magnetic Fields ◽  
Isotropic Medium ◽  
Electric Pulse ◽  
Step Function ◽  
Displacement Current ◽  
Electric And Magnetic Fields ◽  
Time Of Travel

The paper discusses the propagation of a step‐function pulse in a medium characterized by the three electric constants, permittivity ε, permeability μ and conductivity σ. The effect of the displacement current on the propagation is fully taken into account. Expressions of electric and magnetic fields are determined. It is shown that the time of travel of the pulse and the initial and final values of any one of the non‐vanishing field components (all of which can be measured) fully specify the values of conductivity and permittivity of the medium.

THE ELECTRIC AND MAGNETIC FIELDS AT THE SURFACE OF A FLAT CONDUCTING EARTH IN THE NEAR FIELD OF AN OSCILLATING LINE CURRENT

1966 ◽  
Vol 44 (8) ◽  
pp. 1923-1931 ◽  
Author(s):  
H. W. Dosso
Keyword(s):  
Magnetic Fields ◽  
Near Field ◽  
Numerical Calculations ◽  
Line Current ◽  
The Earth ◽  
Electric And Magnetic Fields ◽  
Phase Angles

The electric and magnetic fields at the surface of a flat conducting earth in the near field of an oscillating line current are studied in this work. The equations for the amplitudes and phase angles developed by Law and Fannin (1961) were used for the numerical calculations. The source heights (h = 105 to 4 × 105 meters), the source frequencies (ƒ = 10−3 to 10 sec−1), and the earth conductivities (σ = 10−5 to 10 mho/m) considered are of interest in geophysics.

scholarly journals Propagation of ELF Radiation from RS-LC System and Red Sprites in Earth-Ionosphere Waveguide

2012 ◽  
Vol 1 (2) ◽  
pp. 96
Author(s):  
M. K. Paras ◽  
J. Rai
Keyword(s):  
Magnetic Fields ◽  
Return Stroke ◽  
Schumann Resonances ◽  
The Earth ◽  
Electric And Magnetic Fields ◽  
Red Sprites

In this paper, two different mechanisms return stroke-lateral corona (RS-LC) system and red sprites which excite Earth-ionosphere waveguide have been discussed. The electric and magnetic fields from RS-LC system and red spites in the Earth-ionosphere waveguide have been calculated. It has been found that red sprites contribute to the Schumann resonances (SR) greatly as compared to the RS-LC system.

Infra-low-frequency gravitational wave signals in the electric and magnetic fields of the earth

2017 ◽  
Vol 61 (4) ◽  
pp. 368-375 ◽  
Author(s):  
L. V. Grunskaya ◽  
V. V. Isakevich ◽  
D. V. Isakevich ◽  
V. E. Luk’yanov ◽  
I. A. Leshchev
Keyword(s):  
Magnetic Fields ◽  
Gravitational Wave ◽  
Low Frequency ◽  
The Earth ◽  
Electric And Magnetic Fields

scholarly journals GEOPHYSICS AS A SCIENCE

Geophysics ◽  
1937 ◽  
Vol 2 (3) ◽  
pp. 185-187 ◽  
Author(s):  
B. Gutenberg
Keyword(s):  
Magnetic Fields ◽  
Structure And Properties ◽  
The Earth ◽  
Electric And Magnetic Fields

“Geophysics” means “Physics of the Earth.” While in physics one tries to eliminate the effects of the gravitational, electric, and magnetic fields of the earth, in geophysics these fields, their properties and effects, and the structure and properties of parts of the earth are studied.

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