Electromagnetic whistler‐mode radiation from a dipole in the ionosphere

Abstract

[1] Dipole-antenna radiation theory has been tested for electromagnetic whistler-mode waves in the frequency range 0.1-1.3 MHz using data from the two-point rocket experiment Observations of Electric-field Distributions in the Ionospheric Plasma; a Unique Strategy (OEDIPUS) C. Waves were emitted from a double-V dipole on a transmitting subpayload and received at a distance of about 1200 m on a similar dipole connected to a synchronized receiver. The magnitudes of transmitted signals predicted by a theory for short dipoles have been found to be in good agreement with observations. The agreement is very good in the top two thirds of the frequency range where the dispersion relation and the geometry provide only one saddle-point solution with the required group direction. In this part of the parameter space studied, the transmitterreceiver separation is at least 10 wavelengths. This is not always true at the lowest frequencies, where the expected effects of interference of multiple saddle-point rays and of the oblique resonance cone are observed.

Dependence of quasi‐linear diffusion coefficients on wave parameters

“…Theories of VLF power radiation into a magnetized plasma currently lack consensus and verification, despite substantial analysis [ Wang and Bell , 1972; Bell et al , 2006; Song et al , 2007; Krafft and Zaboronkova , 2010], numerical simulation [ Tu et al , 2008; Chevalier et al , 2010], and experimental studies [ James , 2003; Paznukhov et al , 2010; Pribyl et al , 2010]. One notable theoretical expectation is that VLF waves are radiated most effectively at wavelengths comparable to the antenna length.…”

Quasi‐linear diffusion coefficients for highly oblique whistler mode waves

“…Besides naturally occurring waves, another potential application is to whistler waves radiated by spaceborne transmitters, as is planned for the upcoming Demonstration and Science Experiments mission [ Scherbarth et al , ]. Because of the limited size of practical antennas, such radiated waves are expected to be generated very near the resonance cone [ James , ; Chevalier et al , ; Paznukhov et al , ].…”

Impedance characteristics of an active antenna at whistler mode frequencies

“…A number of theoretical studies of radiation from a short dipole antenna surrounded by plasma have been carried out starting in the 1960s [e.g., Mlodnosky and Garriott , 1963; Balmain , 1964; Despain , 1966]. The subject was extensively studied in the 1970s [e.g., Koons et al , 1970; Shkarofsky , 1972; Kuehl , 1974; Laframboise et al , 1975; Adachi et al , 1977], and work continued later on until recently [e.g., James , 2000; Nikitin and Swenson , 2001; James , 2003]. While these works have brought a conceptual understanding of the antenna‐plasma interaction, some models often lacked self‐consistency, since in most cases electrostatic conditions were assumed and the radiation resistance was not considered in the system.…”

“…Experimental investigations, however, were rare and were mainly made at the ionospheric heights. They were carried out on board the OV3‐3 spacecraft [e.g., Koons et al , 1970], ISIS satellite [ James , 1980], and also rockets [ Chugunov et al , 2003; James , 2003]. In most cases, the measured voltage or antenna potential as function of operating frequency was compared to those calculated using impedance theories for dipole antenna in plasma.…”