Electric field observations of ionospheric whistlers

A Nike-Tomahawk sounding rocket was launched near local noon on November 8, 1966, from Wallops Island with a triaxial electric field experiment using long cylindrical dipoles for sensors. Twenty ELF whistlers with dispersion constants ranging from 0.15 to 0.85 sec^1/2 were detected and identified as having propagated up to the rocket through the E region from the earth-ionosphere waveguide. The data extend to the smallest dispersion ever encountered and the lowest frequencies observed on ionospheric whistlers (60 Hz). The waves were eliptically polarized, becoming more nearly circular at higher altitudes. Analysis showed good agreement between the experimental results and quasi-longitudinal (QL) propagation theory for amplitude, dispersion, and polarization characteristics of the wave once it is away from the D- to E-region boundary. No appreciable effects of negative ions or protons were observed in the dispersion of the whistlers.