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The paper is an extension of the authors' previous work on travelling-wave circular loop and helical antennas immersed in an isotropic compressible electron plasma. In the present paper the expressions for the electromagnetic and electroacoustic components of the radiation field and of radiation resistance in the case of an electrically large multi-turn circular loop antenna in plasma having a travelling-wave current distribution are derived. Finally, treating the multi-turn loop in vacuum as a particular case of the general results for the same in a plasma medium, expressions for electromagnetic field and radiation resistance have been obtained for different loop sizes and the number of turns in it. It is shown that its field and the radiation resistance, both in plasma and in vacuum, are seriously affected by the number of turns in the loop and under certain conditions much higher values of radiation resistance can be obtained. [ABSTRACT FROM AUTHOR]

Expressions for the radiation fields in a compressible electron plasma medium are derived pertaining to the helical antenna of finite size immersed in it. The current distribution on the helical antenna is assumed to be an out-going travelling wave with an arbitrary phase propagation constant. From these general expressions fields of circular loop and linear antennas can be deduced as particular cases. Further, by letting the plasma frequency approach zero in these general expressions, the electromagnetic fields of the usual helical antenna theory can be obtained. It is, therefore, concluded that the radiation field expressions for a helical antenna given in this paper are of a general nature and cover the cases of circular loops and linear antennas in an electron plasma medium and of the helical antenna in vacuum. [ABSTRACT FROM AUTHOR]

The radiation properties of perfectly conducting filamentary circular loops of arbitrary dimensions immersed in a uniform isotropic, compressible electron plasma are studied theoretically. The current distribution on the circumference of the loop is assumed to be a travelling wave with arbitrary phase propagation constant. The far zone fields of the circular loop are obtained and the radiation resistance is then evaluated for both the electromagnetic and electroacoustic modes. From these general results, the problem is reduced to that of the circular loop in vacuum and the consequent results are found to tally with those available in literature. From the detailed study of fields and radiation resistances as put out in this paper, it is shown that the radiation resistance of both the modes is higher in the case of travelling wave loop than in the case of standing wave loop. It is, therefore, concluded that loop antennas on space vehicles may be fed with travelling wave currents rather than with the usual standing wave currents, since in the former case radiation resistance of the electromagnetic mode is enhanced. [ABSTRACT FROM AUTHOR]

In the literature considerable data are available on back-scattering in vacuum from conducting bodies of various shapes. Recently some attempts have been made to evaluate radar cross sections of space vehicles in an electron plasma medium. In the present paper, a comprehensive formulation has been attempted and the scattered power as well as the scattering cross sections of a conducting cylindrical space vehicle. moving in a compressible two-component (electron-ion) plasma, have been evaluated for various modes. It is expected that the work presented here will be helpful in handling certain problems connected with radar returns from space vehicles and their tracking from other Earth-bound stations. [ABSTRACT FROM AUTHOR]

The unified approach applied to magnetoplasma with isotropic pressure given in the earlier work of the authors is extended to include the case of anisotropic pressure. General coupled wave equations have been deduced for such a type of magnetoplasma. Cases of propagation parallel and transverse to the static magnetic field are examined in some detail giving expressions for velocity of various modes. It is shown that the electromagnetic modes, ordinary as well as extraordinary, and the plasma mode are modified due to coupling when propagated in a general direction with respect to the static magnetic field. For the propagation along the static magnetic field the coupling vanishes and the modes are unmodified. Also the waves propagated in this direction do not experience the anisotropic effects of pressure. [ABSTRACT FROM AUTHOR]

When a radiating source is immersed in an isotropic compressive plasma, a longitudinal electroacoustic wave may be excited in addition to the usual electromagnetic wave. These waves produced by linear antennas have been studied by the author in a series of papers. The present paper, called part VI of the series, deals with some features of the electric field associated with electroacoustic waves excited by linear antennas. It is shown that the distribution of the field is oscillatory with broadside symmetry and that the maximum occurs almost in the broadside direction.
The investigations presented in the current paper indicate the electric field of electroacoustic waves to be oscillatory having a maximum almost in a broadside direction. About this direction, as expected for the RCFLA, the P mode electric field pattern is symmetrical. But even for the NREFLA there is some symmetry about the broadside direction which improves further with larger values of (c/v)> 10. Thus the P mode field pattern is symmetrical for both types of linear antennas and so differs from the EM mode field pattern which is know to be symmetrical for the RCFLA and non-symmetrical for the NREFLA.
In the end it may be concluded that for frequencies confined to the first Fraunhofer zone, the assumed sinusoidal current distribution with as the propagation constant forms a workable and reasonably simple model to describe the main salient features of linear antenna performance in a hot plasma. [ABSTRACT FROM AUTHOR]

For the current study of radiation from sources in homogeneous compressible lossy magnetoplasma, a linearized hydrodynamic description of the plasma, with positive ions at rest, is used in conjunction with Maxwell's equations. The governing equations have been reformulated in matrix form in which a tensor characteristic of the compressible magnetoplasma has been used. From this unified formulation, uncoupled wave equations have been deduced for radiation fields of various sources, namely the electric current source, the magnetic current source, the mechanical body force source and the electron flux source. The uncoupled wave equation of the electric field vector is then solved, by the method of the dyadic Green's function, term by term, to give fields of each of these sources. Also from this formulation, a general dispersion relation for lossy magnetoplasma has been deduced. Propagation parallel and perpendicular to the static magnetic field is studied as particular cases. [ABSTRACT FROM AUTHOR]

In a series of studies of linear antennas immersed in weakly ionized plasma, the authors have investigated radiation properties of resonant and non-resonant antennas. In the present work, called part V of the series, radiation field patterns of resonant half-wave dipole and non-resonant optimized linear antennas immersed in weakly ionized plasma are evaluated for three different propagation constants of the current distribution. These are then compared with the corresponding standard patterns obtained in the vacuum. It is concluded that in plasma the fields contributed by the current distribution corresponding to and are predominant and those corresponding to are practically negligible for the EM mode. However, for the P mode fields the situation is just the reverse.
On the basis of the studies given in the present paper it is found that, in isotropic warm electron plasma, the P mode electric field of both types of linear antennas, resonant as well as non-resonant, has an extremely large number of very closely packed maxima and minima. The EM mode electric field, however, has well spaced maxima and minima, fewer in number, having a sharply defined major lobe. The direction of the major lobe is practically independent of the parameter A for the resonant half-wave dipole, but varies to a large extent in the case of non-resonant antenna besides having some more comparable lobes. As regards the magnitudes of the fields, the EM mode field strengths are comparable when equals and , but are three to four orders smaller when equals . The P mode field strengths, however, are also comparable in the first two cases but in the case when equals they are four to seven orders higher. It can thus be concluded that for an equally strong component of the current on the antenna, the field contributed by that distribution is negligible in the EM mode and predominant... [ABSTRACT FROM AUTHOR]

In a series of studios of linear antennas immersed in weakly ionized plasma, the authors have investigated radiation properties of resonant and non-resonant antennas. In parts I and II of the series, propagation constant on antenna wire was considered the same as in free space and the effect of collision frequency was taken into account wherever effective. In part III a general propagation constant for the resonant finite-sized dipole was assumed but the effect of collision frequency was neglected. In the present work called part IV of the series, a thin non-resonant end-fed antenna is employed as a source and radiation in the first Fraunhofer zone under similar conditions is considered. General expressions for radiation resistance for both the electromagnetic and electro-acoustic modes have been obtained. As a particular case, radiation resistance of each mode for optimized linear non-resonant end-fed antenna is calculated and the results are then compared with those of resonant dipole treated earlier in part III. [ABSTRACT FROM AUTHOR]

Coupled wave equations have been developed for the propagation of electromagnetic, electron acoustic and ion acoustic waves in a homogeneous, warm magnetoplasma employing the linearized two-fluid continuum theory of partially ionized plasma dynamics. For the purpose of this study propagation is considered in a plane transverse to the static magnetic field. Coefficients occurring in the dispersion relation have been calculated for two-component electron-ion hydrogen magnetoplasma over a wide frequency spectrum and these are used to study the dispersion relation in various frequency ranges. It is observed that the modified ion plasma mode propagates in the entire range of the frequency spectrum but the electromagnetic mode, ordinary as well as extraordinary, and the electron-plasma mode propagate only in the range higher than the electron plasma frequency. [ABSTRACT FROM AUTHOR]

In earlier works of the authors, called part I and part II of the series of studies of linear antennas immersed in a weakly ionized plasma, the propagation constant for the current distribution along the antenna wire was taken to be the free space wave number. In the present work, called part III of the series, a general propagation constant is assumed and the radiation resistance of the finite-sized dipole is evaluated for the electromagnetic and plasma-acoustic modes. The case of the half-wave dipole is then treated giving different values to the propagation constant. The results so obtained show that the propagation constant of current distribution along the antenna wire may not have one particular value and currents of all the three wave numbers , and may simultaneously be present. [ABSTRACT FROM AUTHOR]

In an earlier work of the author, called part I of the series of studies relating to the radiation from antenna immersed in weakly ionized plasma, a linear resonant centre-fed antenna was used as source. In the present work, called part II of the series, a thin, linear, non-resonant end-fed antenna is investigated under similar conditions. A theoretical study of its radiation resistance for the electromagnetic and electro-acoustic waves is made, taking the propagation constant as complex for both these modes. Also the effect of electron neutral particle collision is taken into consideration wherever effective. It is shown that the effect of plasma is more profound when the source frequency is lower than the plasma frequency. But at frequencies higher than the plasma frequency the effect is found to be not of much consequence. General expressions of radiation resistance for both the electromagnetic and the electro-acoustic waves have been obtained, and from these the behavior of half-wave linear non-resonant end-fed antenna is deduced. These results are then compared with those for half-wave centre-fed dipole treated earlier in part I of these studies. [ABSTRACT FROM AUTHOR]

A theoretical analysis of the plate efficiency and output of a tube operating as class AB radio-frequency amplifier is made. Optimum values of load, C bias, and grid excitation voltage have been calculated which will give-maximum output for a given plate loss. Also under these optimum operating conditions the behaviour of a class AB amplifier is analysed in respect of second harmonic distortion. Ready tables and charts are designed from which these optimum operating parameters and the second harmonic content can be readily evaluated. [ABSTRACT FROM AUTHOR]

Comments on the breakdown voltage of cylindrical positive corona discharges in hydrogen. Presentation of experimental plots of breakdown voltages in hydrogen for positive corona discharges between cylindrical electrodes; Studies on the rectification in gas discharge; Significance of the occurrence of the minimum in the breakdown voltages curves.

Comments on the article 'Radiation Resistance of a Cylindrical Antenna Radiating in Weakly Ionized Plasma,' by Awatar Singh. Expressions for radiation resistance of a half-wave dipole; Assessment on the complex quantity of radiation resistance; Range showing the variation of radiation resistance.

Presents a reply to a comment on radiation characteristics of a linear antenna immersed in plasma. Evaluation on the radiation resistance; Correlation between half-wave dipole and electromagnetic mode in plasma; Impact of collision on radiation resistance.