Excitation of electromagnetic waves by a pulsed loop antenna in a magnetoplasma

Abstract

A study is made of the radiation from a pulsed loop antenna immersed in a cold collisionless magnetoplasma. Using a rigorous solution for the total field of such an antenna, the energy characteristics of its radiation are determined. The radiated energy and its distribution over the spatial and frequency spectra of the excited waves are analyzed as functions of the antenna and plasma parameters. Numerical results referring to the case where the frequency spectrum of the antenna current is concentrated in the whistler frequency range are reported. The results obtained can be useful in understanding the basic features of wave excitation by pulsed sources in a magnetoplasma.

Whistler wave radiation from a pulsed loop antenna located in a cylindrical duct with enhanced plasma density

“…The allowed regions Q 1 and Q 2 of integration in the (x, q) plane for evaluating W coincide with those discussed in Ref. 33. It is worth also mentioning that the results yielded by Eqs.…”

“…On the other hand, it is also expedient to compare the radiation characteristics of the pulsed loop antenna located in such a duct with those in the case where the corresponding source is immersed in a homogeneous unbounded magnetoplasma. 33 To this end, we choose the temporal behavior of the antenna current in the form coinciding with that in Ref. 33, i.e., take a pulse whose filling comprises a few half-periods of a monochromatic oscillation vðtÞ ¼ ½HðtÞ À Hðt À sÞ sinðx 0 tÞ:…”

“…33 To this end, we choose the temporal behavior of the antenna current in the form coinciding with that in Ref. 33, i.e., take a pulse whose filling comprises a few half-periods of a monochromatic oscillation vðtÞ ¼ ½HðtÞ À Hðt À sÞ sinðx 0 tÞ:…”

“…[10][11][12][13]17 We will also compare the efficiency of whistler wave excitation by a pulsed loop antenna in the presence of a density enhancement with the corresponding results referring to the case where such an antenna is immersed in a homogeneous magnetoplasma, which has been analyzed in our recent work. 33 Our article is organized as follows. In Sec.…”

“…16 and 19. Over the past two decades, there has been shown a substantial degree of interest in the excitation of nonmonochromatic waves propagating in the whistler mode in a magnetoplasma. [26][27][28][29][30][31][32][33] This interest has been motivated by the importance of transient phenomena for propagation of whistler-mode waves through the magnetosphere and the ionosphere, as well as for plasma diagnostics using pulsed signals launched from antennas on spacecraft in the whistler range. However, much previous theoretical work on the subject is mainly focused on studying the fields and radiation characteristics of nonmonochromatic sources in a homogeneous magnetoplasma.…”