Far-region electromagnetic radiation with a vertical magnetic dipole in sea

2001 ◽  
Vol 49 (6) ◽  
pp. 992-996 ◽  
Author(s):  
Yunliang Long ◽  
Hongyan Jiang ◽  
B. Rembold
2011 ◽  
Vol 57 (5) ◽  
pp. 610-614 ◽  
Author(s):  
Zhiwen Cui ◽  
Jinxia Liu ◽  
Guijin Yao ◽  
Kexie Wang

Author(s):  
J. Pierrus

This chapter begins by expressing the multipole expansion of the dynamic vector potential A ( r, t) in terms of electric and magnetic multipole moments. Differentiation of A ( r, t) leads directly to the fields E ( r, t) and B ( r, t), which have a component transporting energy away from the sources to infinity. This component is called electromagnetic radiation and it arises only when electric charges experience an acceleration. A range of questions deal with the various types of radiation, including electric dipole and magnetic dipole–electric quadrupole. Larmor’s formula is applied in both its non-relativistic and relativistic forms. Also considered are some applications involving antennas, antenna arrays and the scattering of radiation by a free electron.


2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Lina He ◽  
Tong He ◽  
Kai Li

Dipole antennas over the boundary between two different media have been widely used in the fields of geophysics exploration, oceanography, and submerged communication. In this paper, an analytical method is proposed to analyse the near-zone field at the extremely low frequency (ELF)/super low frequency (SLF) range due to a vertical magnetic dipole (VMD). For the lack of feasible analytical techniques to derive the components exactly, two reasonable assumptions are introduced depending on the quasi-static definition and the equivalent infinitesimal theory. Final expressions of the electromagnetic field components are in terms of exponential functions. By comparisons with direct numerical solutions and exact results in a special case, the correctness and effectiveness of the proposed quasi-static approximation are demonstrated. Simulations show that the smallest validity limit always occurs for component H2z, and the value of k2ρ should be no greater than 0.6 in order to keep a good consistency.


Geophysics ◽  
2001 ◽  
Vol 66 (6) ◽  
pp. 1805-1810 ◽  
Author(s):  
Misac N. Nabighian ◽  
R. O. Hansen

The extended Euler deconvolution algorithm is shown to be a generalization and unification of 2‐D Euler deconvolution and Werner deconvolution. After recasting the extended Euler algorithm in a way that suggests a natural generalization to three dimensions, we show that the 3‐D extension can be realized using generalized Hilbert transforms. The resulting algorithm is both a generalization of extended Euler deconvolution to three dimensions and a 3‐D extension of Werner deconvolution. At a practical level, the new algorithm helps stabilize the Euler algorithm by providing at each point three equations rather than one. We illustrate the algorithm by explicit calculation for the potential of a vertical magnetic dipole.


2000 ◽  
Vol 78 (9) ◽  
pp. 833-844 ◽  
Author(s):  
O M Abo-Seida ◽  
S T Bishay

A theoretical study of the pulsed electromagnetic radiation from a vertical magnetic dipole placed on a plane-conducting earth is presented. The application of a Laplace transformation in time and a Fourier transformation in the two orthogonal, horizontal, spatial components leads, under consideration of initial, boundary, and transition conditions, to an integral representation of the solution of the wave equation in frequency space. A modified Cagniard method is then used to derive closed-form expressions for the magnetic Hertz vector anywhere above the conducting earth. The method is used to perform numeric calculations of the magnetic Hertz vector, for different source-receiver distances, as well as different values of the earth's conductivity and permittivity. PACS Nos.: 41.20Jb, 42.25Bs, 42.25Gy, 44.05+e


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