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The energy in the vicinity of the disk axis collimates efficiently by the continuous wave sine and single cycle sine angular momentum, caused by the radiated energy densities in the Fresnel region due to the excitations. The single sine and cos angular momentum are also considered in the focussing of the energy source.

Careful attention should be given in designing receiver models that match trasmitter models. If voltage and current sources are assigned faithfully, then the assumption that the open-circuit received voltage across a small and thin dipole is proportional to the first-time derivative of the incident electric field is valid. This voltage is also proportional to the third-time derivative of the input voltage across the terminals of a transmitting dipole antenna.

Integral equations for the surface current on a thin cylindrical antenna (finite) immersed in a warm plasma and excited by a delta-function generator are derived. Boundary conditions to be satisfied on the surface of the antenna are also discussed. The deficiency of a recent work on the same problem is commented upon. These integral equations are applied to the special case of an infinite cylindrical antenna and the results are compared with known ones. The zero-temperature limit for a cold plasma and its implication on the boundary condition are also discussed. [ABSTRACT FROM AUTHOR]

A theoretical model of a microwave probe for a re-entry plasma, by using a circular waveguide fed in the lowest-order circular TE mode, is developed. The reflection coefficient or the aperture admittance to the probe is calculated by a variational method. Radiated field is determined by employing the saddle point method of integration. In addition, expressions for surface wave contribution to the field inside the plasma and the reflection coefficient are also presented. The plasma is assumed to be inhomogeneous in the direction parallel to the axis of the waveguide. [ABSTRACT FROM AUTHOR]

Residue contributions to some integrals are presented here. These results are used to calculate the surface wave contribution to the admittance of the open end of a circular waveguide as well as of a coaxial waveguide fed in their respective dominant modes. Both of these waveguides are assumed to be flush-mounted to a fiat conducting plane covered by a dielectric or a plasma slab. [ABSTRACT FROM AUTHOR]

A theoretical study of the radiation from the open end of a coaxial waveguide fed in the dominant TEM mode and flush-mounted to an infinite, perfectly conducting flat ground plane covered by a plasma (or an ordinary dielectric) layer is presented. The aperture admittance for which the contribution from the higher-order TM(n 1) modes is considered, has been calculated by two methods: (1) successive substitution method and (2) variational technique. It is shown that for any desired order of accuracy the results of these approaches are identical. Expressions for the radiated fields and surface waves are also given. In addition to the surface waves, the near fields inside the plasma (or dielectric) layer for a large radial distance from the aperture are obtained. The contribution of the surface waves to the aperture admittance is also discussed. [ABSTRACT FROM AUTHOR]

The problem considers the effect of an angular d.c. magnetic field on the radiation of a uniform magnetic ring source (slot antenna) situated on the surface of an infinitely long metal cylinder covered by a plasma sheath.
It is observed that, in a relatively high density plasma (/ > 1), the application of a static magnetic field improves the transmission of electromagnetic waves. However, it, is shown in this paper that, in a low density plasma for which / < 1, the application of a static magnetic field may deteriorate the transmission of radio waves through the plasma. To substantiate those, statements, both theoretical explanations and numerical results are provided. The numerical results present the comparison of the intensity of the radiated fields for various situations. In absence of a static magnetic field, an increase of collision frequency increases the transmission of radio signals through the plasma, particularly when / > 1. When a static magnetic field is present, the increase of the transmitted signal strength with the increase of v/ through the plasma becomes noticeable particularly for v/ > 1. [ABSTRACT FROM AUTHOR]

The study of the radiation from a vertical magnetic dipole in an inhomogeneous half space and also in inhomogeneous stratified media above a horizontal conducting infinite plane is considered. The formal expression for the Hertz potential, from which all the field components can be derived, is presented in the form of a contour integral. These formal results are employed for special cases using suitable profiles for relative dielectric constants so that the electromagnetic fields can be expressed in terms of known functions. The contour integral is evaluated asymptotically by saddle point method of integration in each of the examples using special profiles for (z). Possibilities of the existence of surface Waves in appropriate configurations are also discussed. The results for homogeneous media are also extracted from those of the corresponding inhomogeneous media by taking appropriate limits. [ABSTRACT FROM AUTHOR]

Mathematical analysis of the radiation from a dielectric coated prolate spheroidal core loop antenna surrounded by a plasma sheath is considered in this paper. In order to satisfy boundary conditions, the angular prolate spheroidal function S(C,) of one region is expanded in terms of another region. Therefore, the formal results are presented in terms of infinite matrices. A choice of the truncation of such an infinite matrix by a finite number of its elements depends mainly on the rapidity of the Convergence of the expansion of the angular spheroidal function for one medium in terms of those for another medium.
In order to determine the nature of convergence of such expansion of angular functions, some numerical results are presented. These results should be useful in the final numerical calculation of the field. Numerical results show that the minimum number of terms in the expansion necessary to approximate the function S(c,) in terms of S1ι(c,) within a given accuracy, remains practically the same when S1ι(c,) is also expanded in terms of S(c,).
In the limit of zero eccentricity, expressions for the corresponding radiation problem for spherical geometry are also presented. This result may be applicable to satellite communications. [ABSTRACT FROM AUTHOR]

This paper considers the possibility of excitation of lateral waves in a compressible plasma in contact with conducting boundaries. The present investigation demonstrates the existence of a peculiar type. of lateral wave which travels a certain distance along the conducting surface with the phase velocity of light in a cold plasma and is then reflected back at the critical angle into the compressible plasma in which the wave propagates with the phase velocity of acoustic waves. These electro-acoustic lateral waves are the contribution to the pressure field integral from the integration around the branch cut which depends on both the velocity of light and the adiabatic sound velocity in plasma-electrons. [ABSTRACT FROM AUTHOR]

The radiation of electromagnetic waves from a loop antenna in a cylindrically stratified media, one of which is a plasma, is considered. Amplitude and phase of the radiation pattern are calculated asymptotically. Numerical results showing the effects of plasma frequency and collision frequency on the radiation pattern (both the phase and amplitude) are present, ed. Numerical results for the case when there is no plasma are also included.
It is shown in both the cases (in the presence and in the absence of the plasma) that the radiation pattern is more sensitive to the change in thickness of the dielectric coating or the plasma sheath than the same amount of numerical change of the dielectric constant of the medium (plasma or ordinary dielectric). At a very high frequency whether p/ is less or greater than unity the radiation pattern is very directive. The angle of maximum radiation increases with the ratio / for certain parameters. It is also shown that in some cases collision frequency helps transmission of signal through a plasma sheath, in particular when / > 1. This information should be useful for re-entry communications. [ABSTRACT FROM AUTHOR]