VHF current distribution on a cylindrical VLF antenna in a magnetoplasma

Insulated Cylindrical Antenna in a Cold Magnetoplasma

“…in the limiting case a 0 → ∞ [17]. It should be emphasized that the eigenmode guided by a perfectly conducting sheathless cylinder can exist only in the case of a gyrotropic plasma.…”

“…Furthermore, it can be shown that the branch points p = ±ε 1/2 of the functionq(p) are not poles of the integrands in (19) and (20). Recall that a perfectly conducting sheathless cylinder immersed in a resonant magnetoplasma can in general support a single axisymmetric eigenmode if ε > 0 and η < 0 [14,17,19]. In what follows we limit ourselves to consideration only of the whistler frequency range.…”

“…The properties of the eigenmode guided by a sheathless cylinder in a magnetoplasma at frequencies (23) and (24) were considered in detail in [17]. It was shown that the propagation constant p = p 0 of the eigenmode can be found by solving the equation…”

“…This is explained by the fact that, in contrast to the standard thin-antenna theory [12], it is now impossible to introduce the customary small parameter of antenna theory in the form of the ratio of the antenna-wire radius to the characteristic wavelength, since there always exist some wavenormal directions for which wavelengths in the plasma medium will be less than the wire cross-sectional extent. Therefore, most analyses of the cylindrical antenna in a resonant magnetoplasma use either the approximate transmission-line theory [13] or treat the current distribution on the antenna surface as a boundary-value problem [14][15][16][17].…”

“…Then the truncation of the antenna to a finite length is performed, which leads to reflections of current waves of similar type from the antenna ends. Using such a waveguide approach, it was shown that, in general, the current on an uninsulated antenna immersed in a resonant magnetoplasma and excited by a voltage source comprises contributions from an eigen (bound) mode, which can exist in some frequency bands [18,19], and from continuous-spectrum waves [14,17]. In some cases important for applications, the eigenmode contribution is found to dominate the current distribution on a fairly thin antenna excited by a delta-function voltage source [17].…”