EFFECT OF ION SHEATH ON RADIATION IN A MAGNETOIONIC MEDIUM: I. SOURCE CURRENT PARALLEL TO THE MAGNETOSTATIC FIELD

1966 ◽  
Vol 44 (7) ◽  
pp. 1401-1418
Author(s):  
S. R. Seshadri ◽  
K. L. Bhatnagar
Keyword(s):  
Point Source ◽  
Electric Current ◽  
Finite Length ◽  
Current Distribution ◽  
Radiation Resistance ◽  
Free Space ◽  
Sheath Thickness ◽  
Radiation Characteristics ◽  
Magnetostatic Field ◽  
Source Current

The radiation characteristics of an axially oriented point source of electric current and a filament of finite length with a triangular current distribution are treated for the case in which these sources are situated at the center of an infinite cylindrical column of free space and surrounded by a homogeneous, loss-free magnetoionic medium. The direction of the magnetostatic field is assumed to be parallel to the axis of the free-space column which is an idealization for the geometry of the ion sheath formed around the antenna in the ionosphere. The dependence of the radiation resistance of these sources on the frequency and the ion-sheath thickness is examined. It is found that, within the framework of the classical magnetoionic theory, the radiation resistance of even a point source of electric current remains finite for all frequencies, provided the ion-sheath effects are included. Also the radiation resistance of a finite-length filament with a triangular current distribution is found to be insensitive to the changes in the thickness of the ion sheath. This result is in conformity with the experimental observations, which indicate no data variations correlated with the changes in the thickness of the ion sheath.

RADIATION FROM A PHASED LINE SOURCE IN A MAGNETOIONIC MEDIUM

1965 ◽  
Vol 43 (9) ◽  
pp. 1636-1648
Author(s):  
H. S. Tuan ◽  
S. R. Seshadri
Keyword(s):  
Electric Current ◽  
Current Distribution ◽  
Free Space ◽  
Line Source ◽  
Propagation Constant ◽  
Electron Plasma ◽  
Radiation Characteristics ◽  
Magnetostatic Field ◽  
Phase Constant ◽  
Special Case

The radiation characteristics of a phased line source of electric current immersed in a magnetoionic medium are analyzed. The line source is assumed to be parallel to the direction of the external magnetostatic field and the phase constant for the current distribution is assumed to be given by k0/β, where k0 is the propagation constant of free space and β is a dimensionless phase parameter. In general, it is found that two modes are excited. The frequency ranges of propagation of these so-called ordinary and extraordinary modes are examined by means of a construction in the Ω2–R2 parameter space for the case [Formula: see text], where Ω = ω/ωp, R = ωc/ωp, and ω, ωp and ωc are the source, the electron plasma, and the gyromagnetic frequency respectively. The dispersion relations and the frequency spectrum are evaluated. It is found that β = 1 is a special case for which only one mode is excited.

EFFECT OF ION SHEATH ON RADIATION IN A MAGNETOIONIG MEDIUM: II. SOURCE CURRENT PERPENDICULAR TO THE MAGNETOSTATIC FIELD

1967 ◽  
Vol 45 (2) ◽  
pp. 279-299
Author(s):  
S. R. Seshadri ◽  
K. L. Bhatnagar
Keyword(s):  
Radiation Resistance ◽  
Free Space ◽  
Magnetized Plasma ◽  
Magnetostatic Field ◽  
Source Current ◽  
Point Electric Dipole ◽  
Two Peaks ◽  
Limiting Case ◽  
Finite Extent ◽  
A Current

The radiation characteristics of current sources situated along the axis of an infinite cylindrical column of free space and surrounded by a homogeneous, loss-free magnetoionic medium are discussed for the case in which the source current is perpendicular to the magnetostatic field. The static magnetic field is assumed to be parallel to the axis of the free-space column, which is an idealization of the ion sheath formed around the antenna in the ionosphere. Both a point electric dipole and a finite and continuous array of the same are investigated. The dependence of the radiation resistance of these sources on the frequency and the ion-sheath thickness is examined. Even in the limiting case of vanishing thickness of the ion sheath, the radiation resistances of these sources are found to be different from those corresponding to an unbounded plasma. In contrast to those in an unbounded magnetoplasma, the radiation resistance remains finite for all frequencies. For the source of finite extent having a current distribution that falls off sufficiently rapidly towards the ends, the radiation resistance is quite insensitive to the changes in the thickness of the ion sheath.The radiation-resistance curve, in general, has two peaks at the so-called dipolar resonant frequencies, which depend primarily on the strength of the magnetostatic field. These dipolar resonances, which are quite analogous to those in an axially magnetized plasma column, are found to become sharper as the radius of the free-space column becomes smaller.

scholarly journals Spherical Helices for Resonant Wireless Power Transfer

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Maja Škiljo ◽  
Zoran Blažević
Keyword(s):  
Radiation Resistance ◽  
Power Transmission ◽  
Wireless Power Transfer ◽  
Antenna Design ◽  
Impedance Match ◽  
Wireless Power ◽  
Radiation Characteristics ◽  
Antenna Size ◽  
Helical Antennas ◽  
Theoretical Considerations

The capabilities of electrically small spherical helical antennas for wireless power transmission at small and moderate distances are analyzed. Influence of design on antenna radiation resistance, efficiency, and mode ratio is examined. These are the factors that, according to the theoretical considerations depicted herein, govern the maximum transfer performances. Various designs and configurations are considered for the purpose, with accent on small-size receivers suitable for implementation in powering common-sized gadgets. It is shown that spherical helix design is easily manipulated to achieve a reduced antenna size. Good radiation characteristics and impedance match are maintained by multiple-arm folded antenna design and by adjusting the separation between the arms.

ELECTRIC POTENTIAL NEAR A SPHERICAL BODY IN A CONDUCTING HALF‐SPACE

Geophysics ◽  
1971 ◽  
Vol 36 (4) ◽  
pp. 763-767 ◽  
Author(s):  
David B. Large
Keyword(s):  
Point Source ◽  
Electric Current ◽  
Half Space ◽  
Electric Potential ◽  
Spherical Body ◽  
Classical Potential

An extensive summary of classical potential solutions has been given recently by Van Nostrand and Cook (1966). This note presents a solution for the potential due to a point source of electric current placed on the earth’s surface in the vicinity of a buried spherical body of arbitrary resistivity. The analysis follows the procedure suggested by Van Nostrand and Cook and is similar to that used recently by Merkel (1969, 1971).

scholarly journals Integrals of the equations of electrodynamics with to the electric constants of a transparent medium

1926 ◽  
Vol 113 (764) ◽  
pp. 237-253 ◽  
Keyword(s):  
Electric Current ◽  
Current Distribution ◽  
Magnetic Force ◽  
Small Radius ◽  
Transparent Medium ◽  
Electric Force ◽  
Present Communication ◽  
Magnetic Current ◽  
Magnetic Forces ◽  
Equations Of Electrodynamics

Integrals of the equations of propagation of electrical disturbances have been given by the present writer which express the electric and magnetic forces at any point outside a surface enclosing all the sources in terms of an electric current distribution and a magnetic current distribution over the surface. The result for a source at a point can be obtained by taking as the surface a sphere of very small radius with its centre at the point. This suggests that the equations representing Faraday’s laws can be written 1/V 2 ∂X/∂ t +4π i x = ∂ϒ/∂ y – ∂β/∂ z , 1/V 2 ∂X/∂ t + 4π i v =∂∝/∂ z – ∂ϒ/∂ x , 1/V 2 ∂z/∂ t – 4π i z = ∂β/∂ x – ∂∝/∂ y (1) – ∂∝/∂ t + 4π m x = ∂z/∂ y – ∂Y/∂y, – ∂β/∂t + 4π my = ∂X/∂ z – ∂Z/∂ x , – ∂ϒ/∂ t + 4π mz ∂Y/∂ x – ∂X/∂ y , (2) where X, Y, Z are the components of the electric force, α, β, γ are the components of the magnetic force, i x , i y , i z are the components of an electric current distribution, and m x , m y , m z are the components of a magnetic current distribution throughout the space. The object of the present communication is to express X, Y, Z, α, β, γ in terms of the electric current and magnetic current distributions and to apply the result to the discussion of the electric constants of a transparent medium. It is convenient to take instead of equations (1) and (2) the following equations, which include (1) and (2) as a particular case

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