Structure of the near zone of a current-loop antenna in a magnetoactive plasma

1988 ◽  
Vol 31 (4) ◽  
pp. 299-308 ◽  
Author(s):  
V. I. Karpman ◽  
A. I. Osin ◽  
O. F. Pogrebnyak
Keyword(s):  
Magnetoactive Plasma ◽  
Loop Antenna ◽  
Current Loop ◽  
Near Zone ◽  
A Current

Response of a current loop antenna in an invaded borehole

Geophysics ◽  
1984 ◽  
Vol 49 (1) ◽  
pp. 81-91 ◽  
Author(s):  
W. C. Chew
Keyword(s):  
Iterative Scheme ◽  
Homogeneous Medium ◽  
Loop Antenna ◽  
Current Loop ◽  
Induction Logging ◽  
Higher Order Terms ◽  
Physical Insight ◽  
The Waves ◽  
Logging Tool ◽  
A Current

The problem of the radiation of a current loop antenna in a multicylindrical medium is formulated exactly in terms of an integral. The integrand is calculated using an iterative scheme making the integral more tenable to approximation. This closely approximates the response of a dielectric logging tool such as the deep propagation tool (DPT) or an induction tool in invaded boreholes. To gain more physical insight into the waves, an asymptotic approximation of the integral is derived. The large parameter for the validity of this approximation is the ratio of the transmitter‐receiver separation to the diameter of the invasion around the borehole. An iterative scheme is devised to compute systematically the approximation for an arbitrary number of cylindrical layers. The multicylindrical layer model is a good model of the invasion zone, borehole, and tool housing. The final approximation to the azimuthal electric field contains three terms. The first term resembles the response of a current loop in a homogeneous medium with electrical properties of the outermost medium or the formation. The higher order terms are improvements. The approximation is better at lower frequencies, implying that it is also good for the induction logging tool.

Magnetic field of a current loop around a Schwarzschild black hole

1974 ◽  
Vol 10 (10) ◽  
pp. 3166-3170 ◽  
Author(s):  
Jacobus A. Petterson
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Current Loop ◽  
Schwarzschild Black Hole ◽  
A Current

Transient fields of a current loop source above a layered earth

Geophysics ◽  
1982 ◽  
Vol 47 (7) ◽  
pp. 1068-1077 ◽  
Author(s):  
G. M. Hoversten ◽  
H. F. Morrison
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Electric Fields ◽  
Current Loop ◽  
Wave Form ◽  
Sign Reversal ◽  
Circular Loop ◽  
Single Ring ◽  
Smoke Ring ◽  
A Current

The electric field induced within four layered models by a repetitive current wave form in a circular loop transmitter is presented along with the resulting magnetic fields observed on the surface. The behavior of the induced electric field as a function of time explains the observed sign reversal of the vertical magnetic field on the surface. In addition, the differences between magnetic field responses for different models are explained by the behavior of the induced electric fields. The pattern of the induced electric field is shown to be that of a single “smoke ring,” as described by Nabighian (1979), which is distorted by layering but which remains a single ring system rather than forming separate smoke rings in each layer.

Using a Current Loop and Homogeneous Primary Winding for Calibrating a Current Transformer

2013 ◽  
Vol 62 (6) ◽  
pp. 1658-1663 ◽  
Author(s):  
Karel Draxler ◽  
Renata Styblikova ◽  
Vlastimil Rada ◽  
Jan Kucera ◽  
Martin Odehnal
Keyword(s):  
Current Transformer ◽  
Current Loop ◽  
A Current

Coulomb wave functions in the theory of the circular paraboloidal waveguide

1988 ◽  
Vol 66 (3) ◽  
pp. 212-227 ◽  
Author(s):  
J. LoVetri ◽  
M. Hamid
Keyword(s):  
Electromagnetic Fields ◽  
Focal Plane ◽  
Focal Length ◽  
Coulomb Field ◽  
Wave Functions ◽  
Field Pattern ◽  
Current Loop ◽  
Far Field ◽  
Far Field Pattern ◽  
A Current

In this paper it is shown how the Coulomb wave functions, commonly used in the description of a Coulomb field surrounding a nucleus, can be used in the description of electromagnetic fields that are symmetric with respect of [Formula: see text] inside a paraboloidal waveguide. The Abraham potentials Q and U, which are useful in describing fields with rational symmetry, are used to simplify the problem. It is shown that these potentials must satisfy a partial differential equation that when separated yields the Coulomb wave equation of order L = 0. Electromagnetic fields due to simple source distributions inside the paraboloid are expanded in terms of these functions. Specifically, solutions for current-loop sources located in the focal plane of the paraboloid are obtained. The case where the wall of the paraboloidal waveguide is assumed to be perfectly conducting is treated as well as the case where the wall has finite impedance. The finite paraboloid is also considered, and the far field is formulated using Huygen's principle. It is found that for the finite surface-impedance case, the far-field pattern due to a current loop operating at 100 MHz in the focal plane of a paraboloidal reflector of 1 m focal length is different from the perfectly conducting case. Specifically, the pattern seems to be more omnidirectional for the impedance case than for the perfectly conducting case. Numerical results are presented for relevant aspects of the problem.

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