Characterization of On-orbit VLF Wave Generation in the inner Plasmasphere*

There has been much interest in the use of whistlers in the inner plasmasphere for interactions with trapped electrons in the Van Allen belts. In preparation for a forthcoming experimental program launching whistlers in the VLF range from a satellite transmitter in this zone, we characterize the radiation from an electric dipole along the projected satellite orbit.  We follow a well-established algorithm to determine the antenna far-fields¹ and couple these results with a three-dimensional ray tracing analysis of the wave propagation. For frequencies between the lower-hybrid frequency and the electron cyclotron frequency there exists resonance cones which dominate the plasma response. The cold-plasma theory produces a singularity result for the radiated power, and hence the antenna impedance, we regularize this with thermal motion or collisional effects to produce a finite value. However, the matching of the transmitter to the antenna will be very sensitive to the background plasma parameters. This work describes the properties of the expected wave propagation and produces quantitative estimates of the transfer function to on-orbit receivers.

1. T. N. C. Wang and T. F. Bell, J. Geophysical Res., 77, 7, Mar. (1972)